Absorbent articles comprising channels with varying bond strengths

Abstract

A personal hygiene absorbent article (20) includes at least one elongated absorbent material free channel (26) having a front end (62) and a back end (66) and a midpoint (64). The channel includes a channel bond (27) between a core wrap top layer (45) and a core wrap bottom layer (46). The channel bond strength varies along the length of the channel such that the bond strength in a middle section (102) is weaker than the bond strength in a front section (100) and a crotch section (104). The bond strength of each section is measured in minutes according to the Static Peel Force Time Test disclosed herein.

Description

Technical Field

[0001] This invention relates to personal hygiene absorbent articles (such as diapers) that include one or more channels located in an absorbent core. Background Technology

[0002] Modern personal hygiene absorbent products, such as baby diapers and adult incontinence diapers, are manufactured by high-speed switching processes involving multiple layers and components. Such absorbent products include a fluid-permeable topsheet on the wearer-facing side of the product, a fluid-impermeable bottomsheet on the clothing-facing side of the product, and an absorbent core positioned between these two layers. This absorbent core typically comprises absorbent material contained within a core envelope. This absorbent material is usually a mixture of cellulose fibers and superabsorbent polymer particles (“SAP”). Over the years, the SAP content relative to cellulose fibers has increased, resulting in thinner absorbent cores. Cellulose-free absorbent cores, also known as fluff-free cores, have recently been proposed. Other typical components of diapers include a collection layer between the topsheet and the absorbent core, as well as inner and outer leg bands. Some absorbent products incorporate a dual-layer collection-distribution system, particularly those with fluff-free cores.

[0003] Many personal hygiene products, particularly baby diapers, now include one or more elongated channels without absorbent material within the absorbent core. These channels help distribute urine rapidly along their length to better utilize the absorbent core's absorbency. The top layer of the core wrapping can be bonded to the bottom layer of the core wrapping within the channels to make the channels more durable and resistant to the delamination pressure of swollen adjacent superabsorbent material. Exemplary disclosures of cores with permanent or semi-permanent channels can be found in WO2012 / 170778 (Rosati et al.) and US2012 / 0312491 (Jackels).

[0004] Channels in the absorbent core can improve the diaper's flexibility, reduce wet sagging, and improve fluid distribution. However, under certain loads, the channels may constrict the core, slowing fluid absorption, especially in the crotch area where SAP is more concentrated and utilized most. The effective capacity of the absorbent core may decrease, and absorption kinetics may also be reduced.

[0005] Various improvements to the channel design have been proposed in patent literature. For example, WO2019 / 83711A1 (Bianchi) discloses an absorbent article comprising at least two discrete channels located within an absorbent material. A first type of channel is provided, in which the top and bottom sides of the core envelope are bonded together, and a second type of channel is provided, in which the top and bottom sides are not bonded or are bonded significantly less than in the first type of channel. Channel bonding can be achieved by adhesive bonding, thermal bonding, mechanical bonding, ultrasonic bonding, or a combination of these methods. Compared to the second type, the first type of channel has a higher static peel force time.

[0006] However, discrete channels may impair the benefits of liquid diffusion and wet bonding. Summary of the Invention

[0007] This invention relates to a personal hygiene absorbent article comprising a front waist area, a crotch area, a back waist area, a longitudinal centerline extending in a longitudinal direction (y), and a length L measured along the longitudinal centerline, wherein the front waist area, the crotch area, and the back waist area have the same length as one-third of L measured along the longitudinal centerline. The article includes a top sheet, a bottom sheet, and an absorbent core located between the top sheet and the bottom sheet. The absorbent core includes a core-covered top layer, a core-covered bottom layer, and an absorbent material layer located between the core-covered top layer and the core-covered bottom layer, wherein the absorbent layer has a length L' measured along the longitudinal centerline in the longitudinal direction.

[0008] The absorbent core includes at least one elongated channel without absorbent material, the channel having a front end, a rear end, and a midpoint, wherein the midpoint is longitudinally equidistantly disposed between the front end and the rear end of the channel. The channel is at least partially present in the crotch area of ​​the article, and the channel has a length L" measured in the longitudinal direction, the length being at least half of L'.

[0009] The channel includes a front section surrounding or adjacent to the front end of the channel, a crotch section surrounding or adjacent to the midpoint of the channel, and an intermediate section located between the front section and the crotch section. The bond strength varies along the length of the channel, such that the bond strength of the channel in the front section and the crotch section is higher than that in the intermediate section. The bond in the front section may also have a higher strength than that in the crotch section. The bond strength (in minutes) is measured according to the static peel force time test disclosed below, wherein the bond strength is measured at a 2.52 cm cut in each section as disclosed herein.

[0010] The absorbent core of the present invention includes at least one channel having segments with different adhesive strengths as disclosed herein. If the core includes a pair of elongated channels arranged symmetrically with respect to a longitudinal axis, each of the pair of channels may advantageously be a channel according to the invention. The absorbent core of the present invention may also include one or more additional channels having an adhesive strength pattern different from the claimed channel.

[0011] By providing a weaker intermediate channel bond strength between the front and middle sections of the channel, swelling pressure caused by the swollen absorbent material can be released in the middle section by preferentially layering the channel bond portion within that middle section. Therefore, the channel bond portion can remain in the front and middle sections for a longer period. This invention provides better fluid handling and, in particular, helps to reduce leakage and / or the use of absorbent material. Attached Figure Description

[0012] Figure 1 A top view of the wearer-facing side of an exemplary article of the invention in the form of an adhesive diaper, which has been flattened out, with some layers partially removed;

[0013] Figure 2 It shows Figure 1 A cross-sectional view of an adhesive diaper;

[0014] Figure 3 It shows Figure 1 A breakdown diagram of adhesive diapers;

[0015] Figure 4 A top view of an exemplary absorbent core, shown separately in the front diagram, is provided, with the top side of the core wrapping partially removed;

[0016] Figure 5 A schematic diagram of the absorber core is shown in an exploded view;

[0017] Figure 6 An irregular adhesive pattern is shown for providing different bond strengths along the channel;

[0018] Figure 6a , Figure 6b , Figure 6c It shows having Figure 6 Close-up view of the front, middle, and intermediate sections of the adhesive pattern channel;

[0019] Figure 7 Straight channels with different bond strengths are shown according to the present invention;

[0020] Figures 8 to 12 An example is provided of how to perform the static peel force time test, which is further described in this article. Detailed Implementation

[0021] Absorbent products

[0022] As used herein, "absorbent article" refers to a personal hygiene device designed to be placed in contact with the wearer's body to absorb and contain bodily fluids. The absorbent articles of this invention include baby care articles, feminine hygiene articles, or adult incontinence articles.

[0023] Baby care products are products intended for use with infants, toddlers and / or children, including adhesive diapers, trouser diapers, absorbent inserts, toddler and / or toddler care wipes, and toddler and / or toddler bibs.

[0024] Feminine hygiene products refer to products involving menstrual pads, incontinence pads, interlabial pads, sanitary pads, pessaries, sanitary napkins, tampons and tampon applicators and / or wipes.

[0025] Adult incontinence products are products intended for use by adults and involve disposable absorbent products, including adhesive diapers, panty diapers, absorbent inserts, incontinence pads, sanitary pads, and vaginal inserts.

[0026] The absorbent articles of the present invention are typically disposable and preferably recyclable.

[0027] As used herein, "diaper" refers to an absorbent product designed to be worn by an infant, toddler, or incontinent adult around the lower body to encircle the wearer's waist and legs and is particularly well-suited for receiving and containing urine and feces. Diapers are generally proposed as adhesive diapers or trouser diapers. Adhesive diapers have a fastening system (e.g., such as...) Figure 1 As illustrated in the illustration, when a diaper is applied to a wearer, a waist opening and a leg opening are formed by releasably attaching the longitudinal edges of the front and back waist areas to each other. In contrast, in a trouser diaper, the longitudinal edges of the waist area are attached to each other to form a pre-formed waist opening and leg opening. The trouser diaper is worn appropriately on the wearer by inserting the wearer's legs into the leg openings and pulling the trouser diaper up to a position near the wearer's lower body. The trousers can be pre-formed using any suitable technique, including but not limited to using repeatable and / or non-repeatable adhesives (e.g., stitching, welding, adhesives, glue bonding, fasteners, etc.) to join the portions of the absorbent article together. The trousers can be pre-formed at any location along the circumference of the article (e.g., side fastening, front waist area fastening).

[0028] This article is about Figures 1 to 2 An exemplary non-limiting absorbent article according to the present invention is discussed. Figure 1This is a plan view of this exemplary diaper 20 in a flat state, with multiple sections of the diaper cut open to show the different layers. The diaper 20 is shown for illustrative purposes only, as the invention can be incorporated into a wide variety of diapers or other absorbent articles, such as trouser-type diapers with pre-formed side seams. If it is necessary to place the trousers in a similar manner... Figure 1 The flat design allows for the opening of the side seams of trousers through cutting or other methods.

[0029] like Figure 1 As illustrated, the absorbent article 20 includes a front edge 10, a rear edge 12, and two longitudinally extending side (lateral) edges 13 and 14. The front edge 10 is the edge of the article intended to be positioned towards the front of the user when worn, and the rear edge 12 is the opposite edge. The absorbent article can be conceptually divided by a longitudinal axis 80 extending along the longitudinal direction y from the middle of the front edge 10 to the middle of the rear edge 12. Therefore, when the article is viewed from the wearer-facing side in a flat configuration, the longitudinal axis conceptually divides the article into two substantially symmetrical halves with respect to this axis, namely the left half and the right half, as shown below. Figure 1 As shown in the example.

[0030] The article has a length L as measured along the longitudinal axis from its front end to its rear end. The transverse centerline 90 is an imaginary line perpendicular to the longitudinal centerline 80 in the plane of the flat diaper, and conceptually divides the article into a front half and a rear half with equal lengths L / 2.

[0031] If parts of an article are under tension due to elastic components, the article can typically be flattened by using clamps along the periphery of the article and / or the adhesive surface, allowing the article to be stretched to become substantially flat. Articles that can be cut open along the side seams, such as trouser-shaped baby diapers, training pants, or adult incontinence pants for young children, to place them on a flat surface, as is known in the art. Unless otherwise specified, the dimensions and areas disclosed herein apply to articles in this flattened configuration.

[0032] Absorbent fabrics (whether adhesive diapers or trouser diapers) can be conceptually divided into a front waist area 36, ​​a back waist area 38 opposite to the front waist area 36, ​​and a crotch area 37 located between the front waist area 36 and the back waist area 38. The crotch area, the front waist area, and the back waist area are thus defined as each third of the length of the absorbent fabric along the longitudinal centerline 80.

[0033] like Figures 1 to 2As illustrated, the absorbent article includes a top sheet 24 on its wearer-facing side, a bottom sheet 25 on its garment-facing side, and an absorbent core 28 located between the top sheet 24 and the bottom sheet 25. The absorbent core 28 includes at least one absorbent layer 60 comprising superabsorbent polymer particles (“SAP”) and a core wrapper. The absorbent layer 60 is disposed between a top core wrapper 45 and a bottom core wrapper 46.

[0034] The absorbent layer 60 typically has a predetermined profile (periphery) as considered in the plane formed by the article when it is laid flat. This profile can be as follows: Figure 3 The absorbent layer is generally rectangular, but it can also have another shape, such as hourglass or dog bone. The absorbent core 28 also includes at least one elongated channel 26 free of absorbent material, which is a substantially absorbent-material-free region within the absorbent layer 60. The channel is typically elongated in the longitudinal direction, such that it extends further in the longitudinal direction y than in the transverse direction x, preferably at least four times. The channel 26 facilitates the distribution of urine along the length of the absorbent article.

[0035] The absorbent article of the present invention may further include a collection-distribution system located between the top sheet and the absorbent core. The collection-distribution system may consist of a single collection layer, or alternatively, as shown in the figure, it may include an upper collection layer 52 located directly below the top sheet, and a distribution layer 54 located between the collection layer and the absorbent core.

[0036] Examples of the collection layer 52 (which can be used alone or in conjunction with the distribution layer) may be a surfactant-treated, latex-bonded nonwoven collection layer. The distribution layer 54 may be a cross-linked cellulose fiber layer, especially when the absorbent core 28 is an absorbent core without fluff pulp. Another example of the collection layer 52 is a hydroentangled layer, which can be used alone or in combination with the distribution layer 54.

[0037] Nonwovens are sheet-like or web-like structures formed by mechanically, thermally, or chemically entangled fibers or filaments. They are flat, porous sheets made directly from individual fibers. They are not made by weaving or knitting, and do not require the fibers to be converted into yarns. Common processes for producing nonwovens include meltblowing, spunbonding, solvent spinning, electrospinning, carding, and air-forming. The basis weight of nonwoven fiber webs is typically expressed in grams per square meter (g / m²). 2 (or gsm) indicates.

[0038] Suitable spunlace nonwovens include absorbent fibers, reinforcing fibers, and elastic fibers, as disclosed, for example, in WO2020 / 205485 (Peri et al.). Spunlace nonwovens typically comprise about 20% to about 75% by weight of absorbent fibers, about 1% to about 50% by weight of reinforcing fibers, and about 10% to about 50% by weight of elastic fibers. However, other materials with fluid collection and distribution properties and integrity may also be used.

[0039] In addition, the absorbent article may include other optional but conventional elements, not shown for simplicity, such as a back elastic feature structure, a front elastic feature structure, an emulsion applied to the body-facing surface of the top sheet, or a urine indicator disposed on the inside of the bottom sheet that changes color upon contact with urine.

[0040] The top sheet 24, bottom sheet 25, and absorbent core 28 can be assembled in a variety of well-known configurations, such as by adhesive bonding, thermal embossing, ultrasonic bonding, or a combination thereof. Exemplary diaper configurations are generally described in US3,860,003; US5,221,274; US5,554,145; US5,569,234; US5,580,411; and US6,004,306.

[0041] Top film

[0042] The top sheet 24 forms the wearer-facing surface of the article, which is in close contact with the wearer's skin (particularly the perineal area). At least a portion (usually all) of the top sheet is liquid-permeable, allowing liquid bodily exudates to easily penetrate its thickness. The top sheet may consist of or contain a carded hot-pressed nonwoven fabric according to the invention, benefiting from the excellent softness of the nonwoven fabric of the invention, especially when the short fibers comprise a combination of natural and synthetic fibers.

[0043] The topsheet may have one or more layers. The topsheet may be open-cell or non-open-cell and may have any suitable three-dimensional feature structure, and / or may have multiple embossed patterns (e.g., adhesive patterns). Any portion of the topsheet may be coated with a skin-care composition, antibacterial agent, surfactant, and / or other beneficial agents. The topsheet may be hydrophilic or hydrophobic or may have hydrophilic and / or hydrophobic portions or layers. If the topsheet is hydrophobic, pores will typically be present to allow bodily fluids to pass through it.

[0044] negative

[0045] The backing sheet 25 is typically the portion of the absorbent article 20 that constitutes all or part of the surface of the absorbent article facing the garment. The backing sheet 25 can be at least partially bonded to the top sheet 24, the absorbent core 28, or other layers of the article by any adhesion method known to those skilled in the art. The backing sheet prevents or at least inhibits the soiling of articles, such as sheets, underwear, and / or clothing, by bodily fluids absorbed and contained by the absorbent core. The backing sheet is typically liquid-impermeable, or at least substantially liquid-impermeable.

[0046] Films typically consist of a thin, impermeable plastic film, usually a thermoplastic film with a thickness of about 0.01 mm to about 0.05 mm. The film material can be breathable, allowing vapors to escape from the absorbent material while still preventing or at least inhibiting bodily fluids from passing through the film. Breathable films can have a strength of 1,000 g / m². 2 / 24h to 15,000g / m 2 / 24h, or 1,000g / m 2 / 24h to 10,000g / m 2 / 24h, or 1,500g / m 2 / 24h to 10,000g / m 2 / 24h water vapor transmission rate (WVTR), if using PERMATRAN-W model 101K (available from Mocon, Inc., Minneapolis, MN) or equivalent, was measured according to the nonwoven standard procedure NWSP 70.4.R0(15) with the following specifications: the experiment was conducted in a laboratory controlled at 23°C ± 2°C and 50%RH ± 2%RH, and the instrument unit was heated to 37.8°C (100°F).

[0047] The backing film 25 may also include a backing film outer cover nonwoven fabric (not shown separately in the figures). The backing film outer cover nonwoven fabric is typically a thin nonwoven material bonded to the outer surface of the backing film. Therefore, the outer cover nonwoven fabric can form the garment-facing surface of the backing film. Thus, the backing film may include a carded, heat-pressed nonwoven fabric according to the invention. In particular, the nonwoven fabric of the invention can form the backing film outer cover, benefiting from the improved softness properties of the nonwoven fabric of the invention. The backing film outer cover nonwoven fabric may also include incorporated patterns, openings, and / or three-dimensional features, which can improve the hand feel of the backing film.

[0048] Barrier hoop 32, 34

[0049] As is known in the art, the absorbent article 20 may also include an inner barrier leg 34 and an outer leg 32. The inner barrier 34 may extend upward from the surface of the article to provide waste retention, while the outer 32 is typically formed in the plane of the base of the article defined by the top and bottom plates. These 32s are preferably elastic, as is known in the art, for example using... Figures 1 to 2 The elastic lines 33 and 35 are shown. Although not illustrated, the absorbent article may also be in the form of a trouser-type diaper comprising inner and outer waistband nonwovens known in the art, in which case the nonwovens of the present invention may also be contained in any inner and outer waistband nonwovens.

[0050] In addition, absorbent articles may include fastening systems, such as adhesive fastening systems or hook-and-loop fastening components, which may include a band protrusion 42 disposed on the back ear flap 40, such as an adhesive band protrusion or a band protrusion including a hook element that cooperates with the landing area 44 (e.g., a nonwoven fiber web providing a loop in the hook-and-loop fastening system). While adhesive diapers typically include a back ear flap 40 and a front ear flap 43, they are not typically present in trouser-type absorbent articles with pre-formed side seams.

[0051] The front and / or rear earpieces may be separate components attached to the absorbent article, or alternatively, may be continuous with portions of the top and / or bottom sheet, such that these portions form all or part of the front and / or rear earpieces 40, 43. Alternatively, the foregoing combination is possible, such that the front and / or rear earpieces 40, 43 are formed from portions of the top and / or bottom sheet, while additional material is attached to form the overall front and / or rear earpieces 40, 43. The front and / or rear earpieces may be elastic or inelastic. Furthermore, the front earpiece 40 may be applied as a separate component attached to the absorbent article, while the rear earpiece (or a portion thereof) may be continuous with portions of the bottom and / or top sheet, or conversely, the rear earpiece may be applied as a separate component attached to the absorbent article, while the front earpiece (or a portion thereof) may be continuous with portions of the bottom and / or top sheet.

[0052] Liquid management layers 52, 54

[0053] The absorbent article may advantageously include at least one liquid management layer 52 located between the top sheet 24 and the absorbent core 28, also referred herein as a collection layer and / or a distribution layer, such as Figures 1 to 2 As illustrated in the figure. The liquid management layer rapidly collects and / or distributes fluid away from the top sheet and into the wick. These liquid management layers are sometimes referred to as "wick layers," "flow layers," "collection layers," "distribution layers," or "collection-distribution layers." Typically, the liquid management layer does not include SAP (Super-Action Packing) because this would slow down the collection and distribution of fluid. Many types of liquid management layers are disclosed in the prior art, see, for example, WO2000 / 59430 (Daley), WO95 / 10996 (Richards), US5,700,254 (McDowall), and WO02 / 067809 (Graef). The liquid management layer is typically positioned symmetrically with respect to the longitudinal axis of the article.

[0054] The liquid management layer 52 can be made of a nonwoven fiber web with hydrophilic properties, commonly referred to as the collection layer. The nonwoven fiber web can be provided, for example, as a continuous roll of material, which is cut to the desired length and pattern as it is unwound in a conversion processing line. This collection layer is typically placed directly beneath the top sheet. Suitable nonwovens are, for example, air-bonded (“TAB”) carded nonwovens, resin-bonded (“RB”) carded nonwovens, spunbond, or hydroentangled (hydraulic entanglement) nonwovens. TAB carded nonwovens can be made, for example, from soft PE / PP bicomponent short fibers. The air-bonded process maintains bulk and compressibility. Resin-bonded carded nonwovens can be made from multi-denier polyester short fibers (e.g., a 50 / 50 or 40 / 60 blend of 6-denier and 9-denier fibers). The elasticity and open structure of resin-bonded carded nonwovens are designed to provide excellent fluid collection properties. Such collection layers can be obtained directly from suppliers such as Fittesa of Simpsonville, South Carolina, USA, or TWE Group GmbH of Emsdetten, Germany. The collection layer can be stabilized by a latex binder such as styrene-butadiene latex binder (SB latex). Processes for obtaining such latex are known, for example, from EP149,880 (Kwok), US2002 / 028858, and US2003 / 0105190 (Diehl). The binder can typically be present in the collection layer in amounts exceeding approximately 12%, 14%, or 16% by weight of the layer. SB latex can be, for example, traded under the name GENFLO. ™ Available commercially from OMNOVA Solutions Inc. (Akron, Ohio), 3160. Latex-bonded collection layers are further disclosed, for example, in US2005 / 033252A1, US2005 / 033253A1, or US2005 / 043694A1 (Schneider). Typical collection layers have a basis weight range of 10 gsm to 200 gsm, particularly 20 gsm to 140 gsm, or 40 gsm to 120 gsm, such as 80 gsm.

[0055] Since the function of the liquid management layer is to help transfer intruding fluid to the absorbent material, it is generally not desirable for the liquid management layer to extend beyond the edge of the absorbent material region of the core. The liquid management layer can typically be rectangular, and its width in the lateral direction can be shorter than the minimum width of the absorbent material layer of the absorbent core.

[0056] When the absorbent material comprises cellulose fibers blended with SAP, a single liquid management layer 52 in the form of a hydrophilic nonwoven collection layer may be sufficient. Cellulose fibers typically aid in the collection and distribution of fluid within the core. However, in cases where the absorbent material of the core is substantially free of cellulose fibers, it may be advantageous to have two liquid management layers, in the form of a combination of a collection layer 52 and a distribution layer 54, as described below and as... Figures 1 to 3 exemplified in any of them.

[0057] The absorbent article of the present invention may include a first liquid layer layer and a second liquid layer layer. These layers may form an integrated, monolithic layer or remain discrete layers attached to each other, for example, by adhesive bonding. The article may include a collection layer 52 located directly below the top sheet and a distribution layer 54 located between the collection layer and the absorbent core, such as... Figures 1 to 3 As illustrated in any of the examples. The distribution layer may include cross-linked cellulose fibers, and the collection layer comprises a carded, resin-bonded hydrophilic nonwoven fabric. The distribution layer may be shaped to have a narrow crotch or to be generally rectangular. A distribution layer having a rounded end facing the back of the diaper (“bullet” shape) has been proposed. Such a dual-layer liquid management layer is disclosed in further detail, for example, in WO2014 / 093323 (Bianchi et al.). Figures 1 to 3 In the example shown, the distribution layer 54 is bullet-shaped, with the crotch portion having a narrower width relative to the front and rear portions of the distribution layer.

[0058] This fiber distribution layer 54 can be fabricated in-line, for example, by depositing fibers (e.g., cross-linked cellulose fibers) onto a forming surface having ridges corresponding to areas where fiber material is not desired. Deposition chambers are known, in which a carrier sheet is disposed on a forming surface having a series of holes connected to a vacuum, such that the vacuum pulls the fibers to desired locations to form the desired deposition layer. The forming surfaces of these deposition chambers can be modified to provide a layer of fiber material having a central portion and side portions separated by folding guides. The fiber layer is typically formed or transferred on the carrier sheet, which should therefore have at least the same dimensions as the fiber liquid management layer. The carrier sheet can be a top sheet, another liquid management layer (such as a nonwoven collection layer 52), or any other layer of the article (e.g., a core wrapper).

[0059] The function of the distribution layer is to distribute invading fluid liquid across a larger surface area within the article, allowing for more efficient use of the core's absorbency capacity. Typically, the distribution layer can be made of a material containing synthetic or cellulose fibers and having a relatively low density. The distribution layer material can be a nonwoven fabric or a fibrous layer containing unbonded or loosely bonded hydrophilic fibers (especially a cross-linked cellulose fiber layer). The density of the distribution layer can vary depending on the compression of the article, but is typically in the range of 0.03 g / cm³ measured at 0.30 psi (2.07 kPa). 3 Up to 0.25 g / cm 3 Specifically, 0.05g / cm 3 Up to 0.15 g / cm 3 The distribution layer may also be a material having a water retention value of 25 to 60, preferably 30 to 45, as indicated in the specification disclosed in US5,137,537.

[0060] This distribution layer 54 may, for example, comprise at least 50% by weight of cross-linked cellulose fibers, optionally consisting of 100% by weight of cross-linked cellulose fibers. The cross-linked cellulose fibers may be pleated, twisted, or crimped, or a combination thereof (including pleated, twisted, and crimped). This type of material has previously been used as part of a collection system in disposable diapers (e.g., US 2008 / 0312622 A1 (Hundorf)), but its application differs from that of this invention. The cross-linked cellulose fibers provide greater elasticity and therefore greater compression resistance under product packaging or usage conditions (e.g., at infant weight). This provides the layer with greater void volume, permeability, and liquid absorption, thereby reducing leakage and improving dryness. The liquid management layer 54 may also typically be shaped such that more material is present in the front and middle of the article relative to the rear of the article. The distribution layer may typically have a density of 30 g / m³. 2 Up to 400g / m 2 Specifically 100g / m 2 Up to 300g / m 2 The average basis weight, wherein the basis weight varies along the length of the article, such that more material is present in the front and middle parts of the layer than in the rear. Therefore, the liquid management layer can be shaped and / or formed into a circle toward the rear of the article, as exemplarily disclosed in WO2014 / 093323 (Bianchi).

[0061] The distribution layer 54 may be provided with a folding guide 31, such as Figures 1 to 3 As illustrated in the example. When the channels 26, 26' of the absorbent core are present, the folding guide 31 can be at least partially stacked vertically with these channels, as shown in the example. Figures 1 to 3As illustrated in the example. Therefore, when adapted to a three-dimensional basin shape, the liquid management layer 54 can be easily folded similarly to the core. "Vertically stacked" means that the position and shape of the folding guide of the liquid management layer corresponds vertically to the channel forming area below the absorbent core, so that when the article is put on and worn by the wearer, the liquid management layer can easily take on the basin shape formed by the absorbent core below.

[0062] The folded guide 31 of the liquid management layer may overlap the core channel 26 of the absorber core along its entire length, but a lower percentage of overlap is also possible. For example, the folded guide of the liquid management layer may overlap for at least 50%, 60%, 70%, or more of the total length of the channel-forming region of the absorber core. In the remaining areas where there is no overlap, the folded guide of the liquid management layer may, for example, be offset relative to the channel-forming region of the absorber core, or may be shorter, thus not extending to the same length as the absorber core channel 26.

[0063] If folded guides 31 are present in this distribution layer, these folded guides can be formed from regions that are substantially free of liquid management material, and in this case, substantially free of unbonded or loosely bonded hydrophilic fibers (such as cross-linked cellulose fibers), such as... Figures 1 to 3 exemplified in .

[0064] However, the invention is not limited to this example with two liquid management layers. Many disposable absorbent articles have only one liquid management layer 52, particularly for cost reasons. As previously indicated, there may also be no liquid management layer between the absorbent core and the top sheet, and / or such a layer may exist below the absorbent core, between the absorbent core and the bottom sheet.

[0065] Absorber Core 28

[0066] The absorbent article of the present invention includes an absorbent core located between a top sheet and a bottom sheet. The absorbent core 28 includes an absorbent layer 60 and a core envelope comprising a top core envelope 45 and a bottom core envelope 46. The absorbent layer typically contains superabsorbent polymer particles (SAP), which are optionally mixed with cellulose fibers. As known in the art, SAP is any water-insoluble, water-swellable polymer capable of absorbing large volumes of fluid. The term “superabsorbent polymer” herein refers to an absorbent material, typically a cross-linked polymer material, capable of absorbing at least 10 times its weight in a 0.9% saline solution (measured using the centrifugation retention capacity (CRC) test specified in EDANA method NWSP 241.0.R2 (19)). SAP may in particular have a CRC value exceeding 20 g / g, or exceeding 24 g / g, or from 20 g / g to 50 g / g, or from 20 g / g to 40 g / g, or from 24 g / g to 35 g / g.

[0067] The absorbent layer 60 is typically sandwiched and preferably at least partially fixed between the top core wrapper 45 and the bottom core wrapper 46, so that the absorbent core can be easily integrated with the rest of the basic structure of the absorbent article in the conversion processing line.

[0068] Superabsorbent polymer particles are typically mixed with cellulose fibers (fluff pulp core). The absorbent core may alternatively contain at least one layer of SAP, where the SAP particles are not mixed with cellulose fibers. Therefore, the resulting absorbent material layer can have a reduced thickness in the dry state compared to conventional fluff pulp-based absorbent cores. This reduced thickness contributes to improved fit and comfort of the absorbent article for the wearer. The absorbent material may be cellulose-free (however, the absorbent core may still contain some cellulose fibers in a nonwoven or paper layer, such as, for example, a spunlace layer as a core wrapping layer).

[0069] Various absorbent core designs, including those without cellulose fibers, have been proposed in the past; see, for example, US5,599,335 (Goldman), EP1,447,066 (Busam), WO95 / 11652 (Tanzer), US2008 / 0312622A1 (Hundorf), and WO2012 / 052172 (Van Malderen). In particular, SAP printing techniques disclosed in US2006 / 024433 (Blessing), US2008 / 0312617, and US2010 / 0051166A1 (both granted to Hundorf et al.) can be used. A method for creating channels in a core without fluff pulp is disclosed in WO2012 / 170798A1 (Jackels et al.), wherein a receiving roller (spreading roller) supporting a core-encapsulated layer on which SAP particles are deposited includes longitudinal mating strips corresponding to the shape of the desired channel, these longitudinal mating strips mating with raised strips on a SAP printing roller. WO2015 / 1253088A1 (Armstrong-Ostle et al.) discloses an improvement to this process in which an auxiliary bonding roller is used to apply pressure by means of mating strips corresponding to mating strips on a spreading roller, thereby providing better overall channel bond strength between the adhesive and the core-encapsulated layer in the channel. Similar methods for creating channel bonds but in the context of fluff pulp (a mixture of cellulose fibers and SAP particles) absorbent materials are known, for example, as disclosed in WO2020 / 188047.

[0070] Absorbent material layers are typically deposited on at least one layer of the absorbent core that serves as a substrate (such as a core-encapsulated bottom layer or a core-encapsulated top layer). In the SAP printing method described in US2008 / 312,622A1 (Hundorf), a continuous SAP layer is obtained by depositing SAP on each core-encapsulated layer in a pattern that separates absorbent material landing areas from non-absorbent material bonding areas. The absorbent material landing areas of the first layer substantially correspond to the non-absorbent material bonding areas of the second layer, or vice versa, such that a continuous SAP layer is obtained when two discontinuous layers are combined.

[0071] The absorbent core may include one or more adhesive layers, and in particular, auxiliary adhesive 70 may be disposed between the inner surface of at least one of the top and bottom layers of the core wrapper and at least a portion of the absorbent layer 46 to adhesively fix the absorbent material (SAP) within the core wrapper.

[0072] The auxiliary adhesive is typically applied by a suitable adhesive applicator, usually a slit-type applicator, which includes a spacer with regularly spaced slits to provide regular application of the auxiliary adhesive to either the top or bottom layer of the core-encapsulated material serving as a substrate. The auxiliary adhesive 70 may extend laterally across the entire width or a portion thereof of the absorbent layer, and the width of the auxiliary adhesive 70 is typically at least 50% of the width of the absorbent layer, such that a significant proportion of the absorbent material is at least partially secured by the auxiliary adhesive. However, the auxiliary adhesive does not necessarily extend along the longitudinal edges 604, 606 of the absorbent layer.

[0073] The auxiliary adhesive 70 typically comprises a series of longitudinal strips separated by gaps. The auxiliary adhesive is present at least in the core channel region 74, which is the region of the core defined longitudinally by the channel. The auxiliary adhesive may also be present in the front core region 72, which is the region of the core located at the front of the channel, and optionally, the auxiliary adhesive is present on the rear core region 76, which is the region of the core located at the rear of the channel. Figure 5 As shown in the example, it is possible to omit the auxiliary adhesive in the back region 76 of the core, since this region of the core can contain relatively less SAP than the rest of the core, and therefore requires less fixation.

[0074] As described in the above-mentioned Hundorf reference, microfiber thermoplastic adhesive webs can also be used for cores without fluff pulp to anchor SAP particles to at least one of the substrates formed by the core wrapping top layer and the core wrapping bottom layer. For simplicity, these adhesives are not shown in the accompanying drawings.

[0075] The basis weight (deposition per unit surface area) of the superabsorbent material can also be varied to produce the profile distribution of the superabsorbent material, particularly in the longitudinal direction to provide more absorbency in the crotch of the work-in-process, but also in the transverse direction, or both directions of the core.

[0076] The core encapsulation is formed by one or two base layers that form a top and bottom core encapsulation layer, which sandwich and at least partially secure the SAP particles, thus maintaining the integrity of the absorbent core. The top core encapsulation layer 45 and the bottom core encapsulation layer 46 are also referred to in the art as the core cover and powder layer, respectively. These core encapsulation layers are typically low-basic-weight nonwovens (typically less than 20 gsm, particularly from 8 gsm to 14 gsm) and can be, in particular, SMS nonwovens (spunbond-meltblown-spunbond laminates), as known in the art. The upper and lower core encapsulation layers can be any material capable of accommodating and supporting the absorbent material.

[0077] The core wrapping layer can be made of the same or different materials, that is, two nonwoven fiber webs with the same or different properties in a C-shaped wrapping configuration. The core wrapping can also be made of a single continuous nonwoven fiber web surrounding the absorbent material layer, as this simplifies the construction and includes a single longitudinal seal. In this case, the top and bottom layers of the core wrapping are made of the same fiber web material.

[0078] These core-encapsulating layers can be bonded face-to-face, at least as... Figure 2 The longitudinal bonding shown is possible, but other bonding configurations are also possible, particularly the C-shaped encapsulation configuration, in which one of the core encapsulation top layer or the core encapsulation bottom layer is larger than the other, allowing the flaps to fold around the absorbent material and attach to another core encapsulation layer.

[0079] The total amount of SAP present in the absorbent core is appropriate for the intended wearer's needs. Newborn diapers require less SAP than diapers for infants or adults with severe incontinence. For a typical baby diaper, the amount of SAP in the core can be, for example, from about 2g to 50g, particularly 5g to 40g. The average basis weight of SAP within the absorbent core can be, for example, at least 50g / m². 2 100g / m 2 200g / m 2 300g / m 2 400g / m 2 500g / m 2 Or larger, or 200g / m 2 Up to 400g / m 2 Average SAP basis weight is the total amount of SAP in the core divided by the area defined by the perimeter of the SAP layer (including any channels, if present).

[0080] aisle

[0081] The absorbent core 28 includes at least one elongated channel 26 free of absorbent material. The channel is a substantially absorbent-free region within the absorbent material layer 60, such that the top core wrapper 45 and the bottom core wrapper 46 can be directly bonded to each other through at least a portion of the channel's length (however, it is not excluded that some superabsorbent particles may accidentally deposit in the channel during core fabrication). The absorbent core may include one or more channels according to the invention, particularly a pair of channels as illustrated, such that the term "channel" as used herein means "one, two, or more channels" unless otherwise specified. The channel preferably does not extend to either side of the absorbent layer and is therefore surrounded by absorbent material.

[0082] The absorbent includes at least one elongated absorbent channel of length L" which is at least 20% of the length L' of the absorbent layer. Unless otherwise stated, all lengths reported herein are measured in the longitudinal direction y (i.e., length refers to the length measured as projected onto the longitudinal axis). The length L" of the elongated channel may be 20% to 80%, 20% to 70%, or 30% to 60% of the length L' of the absorbent layer. The elongated core channel may have a length L" of at least 12 cm. The absorbent core may include a pair of such channels symmetrically arranged on each side of the longitudinal axis 80, wherein these channels may be straight, curved, or a combination thereof. This pair of channels may be disconnected, such as... Figure 2 As illustrated in the illustrations. Channels may also be joined at one or both ends to form a U or O shape, for example. Examples of channel shapes are disclosed in more detail in WO2012170778A1 and WO2012170781 (Kreuzer et al.). Channels may have other shapes; for example, there may be a single straight channel aligned with the longitudinal axis, or there may be a channel with a central rod and two or more branches on each side of the longitudinal axis.

[0083] The article of the present invention may include at least one elongated channel 26 without absorbent material, the channel having a front end 62, a rear end 66, and a midpoint 64. The front end 62 and the rear end 66 of the channel are the front end and the rear end of the channel, respectively. "Front end" and "rear end" refer to the parts closer to the front edge and the rear edge of the article, respectively.

[0084] The midpoint 64 of the channel is a point that is equidistantly positioned longitudinally between the front end 62 and the rear end 66 of the channel. The midpoint 64 exists in the crotch area 37 of the product, so that the channel is approximately centered on the crotch area 37 of the product.

[0085] The channel includes a channel adhesive portion 27 located between the top and bottom layers of the core-encapsulated material. The adhesive portion 27 may extend at least between the midpoint 64 and the front end 62 of the channel and provides structural integrity of the channel in a dry state and at least partially in a wet state. When the surrounding absorbent material swells during use, the channel may form a three-dimensional groove at least partially along the adhesive region of the channel. Any known bonding technique in the art can be used to provide this adhesive portion, particularly selected from adhesive bonding, thermal bonding, mechanical bonding, ultrasonic bonding, or any combination thereof. However, adhesive bonding is preferred because it allows for easy control of the channel adhesive strength without the risk of damaging the core-encapsulated material in the channel region.

[0086] The channel adhesive 27 may be formed at least partially by channel adhesive deposited on at least one of the inner surface of the top layer of the core package or the inner surface of the bottom layer of the core package, and another core package layer is positioned in contact with the adhesive such that the channel adhesive adhesive is formed between the bottom layer and the top layer of the core package through a channel without absorbent material. The channel adhesive may consist of or contain auxiliary adhesive 70, as discussed further below.

[0087] According to the invention, it is advantageous that the channel comprises a front section, a crotch section, and a middle section having substantially different channel bond strengths, as will be detailed and illustrated below. The front section 100 is disposed adjacent to or surrounding the front end 62 of the channel. The crotch section 104 of the channel is disposed adjacent to or surrounding the center point 64 of the channel, and the middle section 102 is disposed between these two sections. The channel bond strength (in minutes) is measured using a static peel force time test, which measures the channel bond survival time of a 2.54 cm (1 inch) wide cut core laminate sample (2.54 cm is measured in the longitudinal direction). The static peel force time test method is described in more detail below regarding how the channel section is sampled from the core laminate and how the bond strength is tested.

[0088] According to the invention, the bond strength varies along the length of the channel, such that the channel bond strength in each of the front and crotch sections is higher than that in the middle section. The bond strength of each section is measured in minutes according to the static peel force time test disclosed below.

[0089] In other words, the bond strength in the middle section is lower than that in the front and crotch sections. Therefore, the middle section is designed with weaker bond strength, and this section allows for the initial release of swelling pressure in the core through the layering of the channel adhesive. The middle section is advantageously positioned near or within the area where urine is typically first delivered to the diaper (the so-called "pee spot"), thus the design of this invention allows swelling pressure to be released first in the most needed part of the core, while maintaining the functionality of the channels in the crotch and front sections of the diaper.

[0090] The crotch section 104 surrounds or is adjacent to the midpoint 64 of the passage. The crotch section 104 may be particularly longitudinally centered at the midpoint 64 of the passage.

[0091] The front section of the channel surrounds or is adjacent to the front end 62 of the channel. In particular, the front section of the channel may be set at a longitudinal distance of 23 mm from the front end 62.

[0092] Intermediate section 102 is disposed between the front section and the crotch section. According to the invention, the channel strength of at least one sample selected anywhere in the intermediate section should be lower than the channel strength in the front section and the crotch section. Intermediate section 102 is disposed between the front section 100 and the crotch section 104. At least one intermediate section 102 of length 2.54, taken at any point between the front section and the crotch section, should have the adhesive strength indicated as claimed.

[0093] Bond strength, in minutes, is measured according to the static peel force time test described in this article.

[0094] The bonding strength of the intermediate section can be at least 2 minutes, particularly 2 minutes to 100 minutes, and more particularly 4 minutes to 50 minutes.

[0095] The front section may have a bond strength of at least 20 minutes. The maximum bond strength measurable by test design is 999 minutes; however, for practical purposes, the maximum bond strength of the front section may be a maximum of 500 minutes, or a maximum of 400 minutes, or a maximum of 300 minutes, or a maximum of 200 minutes. Therefore, the bond strength of the front section may be in the range of 20 minutes to 500 minutes, or 20 minutes to 400 minutes, or 20 minutes to 300 minutes, or 20 minutes to 200 minutes.

[0096] The bond strength of the front section can be approximately the same as, or preferably higher than, the bond strength of the crotch section.

[0097] The crotch section may have a bond strength of at least 20 minutes. The bond strength of the crotch section may be in the range of 20 minutes to 500 minutes, or 20 minutes to 400 minutes, or 20 minutes to 300 minutes, or 20 minutes to 200 minutes. The bond strength of the front section may optionally be at least 10 minutes higher than the bond strength of the crotch section, for example, the bond strength in the front section may be 10 minutes to 200 minutes higher than the bond strength in the crotch section.

[0098] The bond strength of the crotch section 104 may be at least twice the bond strength of the intermediate section 102. The bond strength of the crotch section 104 may be, in particular, between two and thirty times the bond strength of the intermediate section (as measured in minutes according to the static peel force time described herein).

[0099] The bond strength of the front section 100 may be at least twice the bond strength of the middle section 102. The bond strength of the front section 100 may be, in particular, between two and thirty times the bond strength of the middle section 102 (as measured in minutes according to the static peel force time described herein).

[0100] Adhesive pattern 70

[0101] The absorbent core advantageously contains an adhesive. Typically, a hot melt adhesive is used in the core fabrication process. Hot melt adhesives are solid at room temperature, so when applied to a substrate, they are usually heated to a molten state. Before re-curing (this is known as the open time), an adhesive layer can be formed by pressing another substrate onto the first substrate using the adhesive.

[0102] The absorbent core of the present invention includes an auxiliary adhesive 70 that at least partially secures absorbent material to at least one of the top or bottom layers of the core wrapper. This securing is prior to the use of the absorbent material, ensuring that the absorbent material remains in its proper position within the core wrapper before use. The auxiliary adhesive may be applied, typically by slit-type adhesive application or by any other means, to the inside of the top and / or bottom layers of the core wrapper.

[0103] The adhesive may also be present in the core wrapper at least in the channel region 74, and at least partially form a channel bond 27 between the top and bottom layers of the core wrapper. By applying pressure in the channel region 74 during the core fabrication process, the two layers of the core wrapper are brought into contact through the channel, and the adhesive provides an adhesive bond between the two layers through the channel. Exemplary patent disclosures of such adhesive bonding processes for fluff pulp absorbent cores or absorbent cores without fluff pulp can be found in WO2012 / 170798A1 (Jackels et al.), EP2,905,000 (Jackels et al.), and EP2,905,001 (Armstrong-Ostle et al.).

[0104] By varying the amount of adhesive along the length of the channel, varying bond strengths can be obtained between different channel sections. In this case, the front and crotch sections can each contain more adhesive per unit channel area than the middle section. The adhesive pattern can vary along the channel, as shown in the following example.

[0105] The auxiliary adhesive 70 can also be advantageously used to form the channel bonding portion 27. When the channel 26 is at least partially curved or angled relative to the longitudinal axis, at least between the front end 62 and the midpoint 64 (in other words, when the channel is not straight and parallel to the longitudinal direction), the auxiliary adhesive 70 can be applied in an irregular pattern to provide different channel bonding strengths in the front, middle, and crotch sections of the channel. This can be a particularly simple and effective way to provide different strength values ​​in the channel, especially when the channel is curved (e.g., Figure 5 (as illustrated in the example) or straight but at an angle relative to the longitudinal axis.

[0106] In contrast to conventional auxiliary adhesive patterns that include a regular series of longitudinal strips with uniform width and spacing (typically 1 mm) between strips, the strips of auxiliary adhesive 70 according to this irregular pattern can have different widths in the channel region 74, such that due to the curvature or angle of the channel relative to the longitudinal axis, the channel passes through larger or thinner adhesive strips in each of the front, middle, and central sections. Alternatively or additionally, the auxiliary adhesive pattern may include varying gaps between the strips. In this way, the channel region intersecting with strips having smaller gaps will have a higher adhesive content compared to the channel region intersecting with strips having larger gaps between them.

[0107] The auxiliary adhesive pattern 70 that can be used to form the channel adhesive portion 27 according to the invention Figures 5 to 6 Example in Figure 6 A close-up view of the longitudinal strip pattern of the auxiliary adhesive 70 is shown. The auxiliary adhesive 70 can be applied to the top layer 45 or the bottom layer 46 of the core wrapper, or even both. The shape of the channel 26 is shown in dashed lines. The front section 100, the middle section 102, and the crotch section 104 are also shown in dashed lines.

[0108] The auxiliary adhesive strip may include one or more first strips 82 having a first width and one or more second strips 84 having a second width, wherein the second width is greater than the first width. The second width of the second strip 84 may be at least two or at least three times the first width of the first strip 82. The lateral gap or distance between the strips may also vary to adjust the amount of adhesive in each channel segment considered. Thus, the gap between the strips may include a first gap 86 having a first gap width and a second gap 88 having a second gap width, wherein the second gap width 88 is greater than the first gap width 86, for example, the second gap width may be at least two, three, or more times the first gap width 86.

[0109] By positioning the larger adhesive strip 84 to intersect with the front section of channel 26, a larger amount of adhesive per channel area is provided in the front section 100, such as... Figure 6c As illustrated in the close-up view. Similarly, by laterally setting larger gap regions 88 such that these gap regions intersect with the middle section of the channel, where there is less adhesive per channel area, a weaker channel bond is created, such as... Figure 6b As shown in the middle section 102, longitudinal strips 86 with smaller widths, separated by smaller gaps 88, can intersect with the crotch section of the channel, as shown in the figure. Figure 6a As shown in section 104, this results in a medium channel bond strength, which is stronger than the bond strength in the middle section but may be weaker than the bond strength in the front section. It should also be noted that due to the better uniformity of the adhesive in larger strips, the bond strength may increase disproportionately with increasing strip width; for example, note that a pair of 1mm strips separated by a 1mm gap can provide a weaker bond than a 2mm wide strip.

[0110] It was found that using an auxiliary adhesive pattern 70, comprising a series of longitudinal adhesive strips 82, 84, with varying widths and / or gaps to vary the channel bond strength along the channel length, is simple and cost-effective. The regularly arranged longitudinal adhesive strips applied from the gasket are a standard adhesive application pattern commonly used for auxiliary adhesive adhesives. Therefore, channel bonding designs can be easily obtained by adjusting the gasket pattern from having regular widths and gaps to irregular, continuous widths and / or gaps to suit the channel design under consideration.

[0111] However, this irregular auxiliary adhesive pattern using vertical stripes may not be directly applicable to straight channels parallel to the longitudinal direction. In such cases, it may be necessary to use an irregular, laterally oriented auxiliary adhesive pattern to achieve the same effect.

[0112] Figure 7An alternative adhesive application pattern is shown, which can be used alternatively for this straight channel 26s. In this alternative embodiment, the channel adhesive can be applied using an applicator that can vary the amount of adhesive discharged along the length of the channel. Figure 7 The example illustrates adhesive applied in a spiral pattern, wherein the number of vortices per unit length of the spiral is high in the front section 100, medium in the crotch section 104, and low in the middle section 102. More generally, the adhesive pattern has a region 77 with a relatively large amount of adhesive overlapping the front section 100, a region 79 with a medium amount of adhesive overlapping the crotch section 104, and a region 78 with a relatively small amount of adhesive located in the middle section. Adhesive applicators capable of varying the amount of adhesive deposited are disclosed, for example, in US2005 / 0,137,549A1 (Lindsay et al.) and are a good practical solution for straight channels parallel to the longitudinal direction.

[0113] While using an irregular auxiliary adhesive pattern may be a preferred method for obtaining the channel adhesive portion of the present invention, other possible implementations may also be used to achieve the same purpose.

[0114] Another possible implementation involves applying varying pressure along different sections of the channel, such that the channel bond strength varies according to the pressure pattern. In the core channel fabrication process (see references above), pressure is typically applied in the core channel region 74 to achieve sufficient contact between the core encapsulation layer and the adhesive during the adhesive's open time, thereby improving the channel bond strength in the channel region.

[0115] Generally, in channel bonding processes, the core is briefly pressed between a mating strip on a first roller and another mating strip on a second roller or alternatively a smoothing roller, so that the adhesive can effectively attach the two layers of the core wrapper through the channel. See, for example, WO2012 / 170798A1 (Jackels et al.) and WO2015 / 1253088A1 (Armstrong-Ostle et al.), which disclose auxiliary bonding rollers for applying pressure by means of mating strips corresponding to mating strips on a spreading roller.

[0116] By using a channel bonding tool that applies varying pressure along the length of the channel, the bond strength can also vary along the channel (independent of the channel shape). One or both of these mating strips can be machined according to the disclosed channel bonding process such that the profile of the mating strip includes small but effective recesses in a section corresponding to the middle section of the channel, allowing less pressure to be applied to the core channel in that section. This profile can be further modified to provide more pressure in the crotch section than in the preceding section.

[0117] Therefore, in this embodiment, a regular pattern of longitudinal strips of auxiliary adhesive can be applied to the channel region 74, for example, as an auxiliary adhesive comprising a regular series of 1mm longitudinally extending strips of adhesive separated by equal 1mm wide gaps, and each segment of the channel can be applied with different pressures during the bonding process to obtain the bonding pattern of the present invention. In this embodiment, the shape of the channel (straight or curved) is not limited.

[0118] process

[0119] The channel bonding portion 27 may be formed at least partially by auxiliary adhesive 70 deposited on at least one of the inner surface of the top layer of the core wrapper or the inner surface of the bottom layer of the core wrapper in the channel region 74. The process for fabricating the core and forming the core wrapper bonding portion as indicated above may include the following steps:

[0120] Set the first core wrapping substrate;

[0121] A first auxiliary adhesive is applied to the first core encapsulation substrate;

[0122] The first auxiliary adhesive includes multiple parallel auxiliary adhesive strips, wherein two adjacent auxiliary adhesive strips are separated by a gap;

[0123] The first absorbent material is deposited on the first core-encapsulated substrate.

[0124] The first absorbent material is at least partially fixed by the first auxiliary adhesive;

[0125] The first absorbent material layer formed by the first absorbent material includes at least one elongated channel without absorbent material;

[0126] Set a second core wrapping substrate;

[0127] The above layer is combined with the second core encapsulation substrate to form an absorbent core.

[0128] Optionally, a second auxiliary adhesive and / or a second absorbent layer may also be applied to the second core-encapsulating substrate. The first and second auxiliary adhesives may each have an irregular pattern as described herein, or a combination of the first and second auxiliary adhesives may be specific to the auxiliary adhesive pattern of this invention. This optional choice may be more expensive because a second adhesive applicator may be required, but it provides better absorbent material retention when the auxiliary adhesive is applied from both sides of the absorbent material layer. In any case, the resulting auxiliary adhesive pattern is an irregular pattern, as will be described in further detail below.

[0129] Of course, other steps may also be involved in the fabrication of the absorbent core. For example, for cores without fluff pulp made using SAP printing technology, the absorbent material is typically applied as a half-layer to each core-encapsulating substrate, and includes an additional microfiber mesh to secure each half-layer of absorbent material, as described above. On the other hand, fluff pulp cores (containing a mixture of cellulose fibers and superabsorbent particles) can be adequately secured by an auxiliary adhesive layer, and combinations of a first and a second auxiliary adhesive layer are also possible.

[0130] Typically, hot melt adhesives are used as auxiliary adhesives or microfiber adhesives in the core fabrication process. Hot melt adhesives are solid at room temperature, so when applied to a substrate, they are usually heated to a molten state. Before re-curing (this is known as the open time), an adhesive layer can be formed by pressing another substrate onto the first substrate.

[0131] Example

[0132] This invention is applicable to a wide range of absorbent cores and absorbent articles. As is known in the art, the dimensions and materials used can vary depending on the intended application. For example, absorbent cores for larger diaper sizes are typically longer and larger than those for smaller diaper sizes and contain more absorbent material.

[0133] Example 1 :

[0134] The following illustrates the dimensions and materials of exemplary articles and absorbent cores, such as... Figures 1 to 6 The label indicates and includes a pair of core channels and a pair of distribution channels located in the distribution layer. The indicated size is for a "Midi" size diaper, recommended for infants weighing between 7kg and 18kg. All widths are measured parallel to the transverse direction (x), and all lengths are measured parallel to the longitudinal direction (y).

[0135]

[0136] The core encapsulation consists of a top layer (such as a C-shaped wrap around the bottom layer with an adhesive longitudinal seal) Figure 2(As shown). The top layer is 165 mm wide, and the bottom layer is 130 mm wide. The final core bag width is approximately 120 mm. The top layer is an 8 gsm water-permeable acrylic spunbond nonwoven fabric (from Fitesa Germany), and the bottom layer is a hydrophobic 10 gsm nonwoven fabric (from Fibertex). The core package is sealed by gluing at its front and rear edges. The absorbent material consists entirely of SAP particles, half of which are deposited on the top layer of the core package and the other half on the bottom layer, and are secured by microfiber adhesive (as described above using the SAP printing method). An auxiliary slit-type adhesive layer is disposed on the inside of the top layer of the core package, which has a total width of 81 mm and is as shown. Figure 6 The pattern shown is an alternating stripe design (small stripe 82 is 1 mm wide, large stripe 84 is 3 mm wide, small gap 86 is 1 mm wide, and large gap 86 is 3 mm wide). The total amount of SAP in the core is 12.8 g. The absorbent layer has a generally rectangular shape. The basis weight of the SAP in the absorbent layer is longitudinally shaped to allow for greater absorbency towards the center and front of the core. The total length of the core wrapper is approximately 10 mm longer than the length of the absorbent material layer in the front and rear sections to provide a front core wrapper end seal 280' and a rear core wrapper end seal 282'.

[0137] The diaper with an absorbent core includes a dual collection-distribution system comprising a latex-bonded nonwoven collection layer 52 and a cross-linked cellulose fiber distribution layer 54 located between the collection layer and the absorbent core, having the characteristics described above. Figures 1 to 6 The shape is roughly illustrated in the figure. In this embodiment, the width of the rectangular acquisition layer 52 is 105 mm, and the maximum width of the distribution layer 54 is 80 mm.

[0138] The diaper size being compared is size 4 commercial diaper (Baby-Dry). ® The comparative diaper (Western European version) is manufactured on the same conversion line as the diaper of the embodiment. The comparative diaper has channels of the same shape in its core and distribution layer as the diaper of the present invention. Each of the comparative diapers contains 13.1 g of SAP, compared to 12.8 g of the same SAP in the diaper of the present invention. The comparative diaper has a rectangular absorbent layer 110 mm wide and a substantially rectangular distribution layer 80 mm wide (also including a rounded rear edge as in the diaper embodiment). Another key difference is that the comparative diaper has a regular auxiliary adhesive pattern (including continuous 1 mm strips separated by 1 mm gaps over a width of 81 mm), instead of the auxiliary adhesive pattern described above in the present invention. The core construction is similar in other respects for both Embodiment 1 and the comparative diaper.

[0139] test :

[0140] Channel bond strength in different sections of the channel was measured using the static peel force-time test described below. The results are indicated in Table 1 below.

[0141]

[0142] Table 1

[0143] The comparative diaper and the diaper of the present invention were worn on an infant-sized articulated mannequin with a fluid inlet at the crotch that allowed saline solution to flow out to simulate urine flow. A first flow of 150 ml of urine was injected while the mannequin was in a standing position. The mannequin was then tilted forward to simulate an infant's prone position. A series of 25 ml flows were then injected, with a 2-minute pause between each flow, until leakage began at the front of the diaper. Measurements were repeated on five diapers for each of these diaper examples.

[0144] The invention illustrates that, in this front-leaking solution, the average urine load at failure is higher (total diaper load increases by 15g and the load measured in the core increases by 18g). This is excellent considering that the invention contains 0.44g less SAP than the comparative example.

[0145] The sag value of the diapers was further tested under laboratory conditions. The diapers were attached to a skewed support, with the front edge of the diaper positioned on the higher side of the sloping surface. Then, 75 g of saline solution was applied at a distance of 170 mm from the front edge of the diaper. After this, three more applications of 75 g of saline solution were applied at the same point, with a 5-minute pause between each application. The amount of unabsorbed liquid (sag) was measured in grams after each fluid application. Eight samples were tested for each of these diaper examples.

[0146] In the second series of sag measurements, the diapers of the present invention and comparative diapers were tested again, but these diapers were placed in opposite positions, with the rear edge of the diaper positioned higher, and the top sheet removed to focus the measurements on the middle and final storage capacity of the core and the collection-distribution layer. Liquid was applied again at 170 mm from the front core edge, and a 4 × 75 g saline solution was applied, with 8 samples measured for each embodiment. The average results are reported in Table 2 below.

[0147]

[0148] Table 2

[0149] The suffix "s" in Table 2 indicates statistically significant differences between the inventive examples and the comparative examples at a 95% confidence level. The inventive examples exhibited statistically significantly lower sagging for the fourth and final ejaculation in the conventional sagging test, and also statistically significantly lower sagging for the final ejaculation in the reverse sagging test. Furthermore, for the inventive examples, the core load was higher in the reverse sagging test, despite the absorbent core containing 0.3 g less SAP, indicating more efficient utilization of the absorbent material.

[0150] Test methods

[0151] Unless otherwise specified, the values ​​shown herein were measured according to the methods described below. Unless otherwise specified, all measurements were performed at 22°C ± 2°C and 50% ± 5% RH, and samples should be kept outside the bag under these conditions for at least 24 hours to reach equilibrium before testing.

[0152] Static peel force time test

[0153] The purpose of this method is to evaluate the viability of channel bond samples. This test method measures the time (static peel time) under standardized conditions when the channel bond can withstand a constantly applied vertical peel force of approximately 150 grams.

[0154] equipment

[0155] Medium Binder Clip, 25mm capacity (#72050). ACCOWorld Product. Other suppliers: Yihai Products (#Y10003), Universal Office Products (#10210), Diamond (#977114), or equivalent. Clip weight: 4.5g + / - 1g.

[0156] Large Binder Clips, 2 inches (50.8mm). ACCOWorld Product. Other suppliers: Yihai Products, Universal Office Products, Diamond, or equivalent suppliers.

[0157] Test bench…RT-10 room temperature (shear tester) with timer. ChemInstruments, 510 Commercial Drive, Fairfield, Ohio 45014-9797, USA; or equivalent. Must be placed in a vibration-free area.

[0158] Weights……………150g (+ / - 1g) TW150, shear tester weights with hooks on top (to attach to the clamps). ChemInstruments, 510 Commercial Drive, Fairfield Ohio 45014-9797, USA; or equivalent.

[0159] Cutting tools…. Scissors and a 25.4mm (1-inch) cutter (a readily available source, such as the JDC precision sample cutter made by Thwings-Albert Instrument Company (Philadelphia USA, catalog number 99), with a cutting width of 25.4mm and an accuracy of at least + / - 0.1mm).

[0160] Metal rulers…traceable to NIST, DIN, JIS or other equivalent national standards, with millimeter graduations, longer than the length to be measured.

[0161] Temperature…Testo-temperature device (or equivalent) for measuring the temperature at a sample height, with an accuracy of ±0.5℃ and ±2.5% RH within the range of -10℃ to +50℃. Testo GmbH & Co., Postbox 1140, D-79849 Lenzkirch (www.testo.com). Part number for Testo 625: 05636251.

[0162] Core fabrication (see Figure 8 ) :

[0163] After production, the absorbent product is placed in its sealed packaging for at least one week to allow the bond strength to stabilize. The absorbent core can be extracted from commercial products (diapers hereinafter, but this method is applicable to other types of absorbent products) as follows:

[0164] 1. Open the diaper with the top side facing up and place it flat on the work surface. For the pants, open the side seams and remove the waistband. Hold the diaper with one hand and carefully remove the ear flaps (40) and barrier bands (34) along the continuous adhesive portion (outer edge) on both sides of the garment.

[0165] 2. Gently remove the top film and acquisition system, taking care not to damage the core end seal (if present). The film does not need to be removed.

[0166] Preparation of channel samples (see) Figure 9 ) :

[0167] For each channel, proceed as follows:

[0168] 1. Place the core under a desk lamp or UV lamp to mark the beginning (62) and end (66) of the channel.

[0169] 2. Define the longitudinal midpoint (64) of the core channel (26) by using a ruler.

[0170] 3. Mark the crotch transverse line perpendicular to the longitudinal axis, passing through the midpoint (64) of the channel. Similarly, mark the front transverse line at the desired location toward the front end of the channel, specifically at a distance of 23 mm from the front end (62) of the channel in the longitudinal direction, and mark the middle transverse line at the desired location in the middle section between the front transverse line and the crotch transverse line. Specifically, the middle transverse line may be set at a distance of 23 mm from the front transverse line. These transverse lines are used to center the cutter blade, which will cut a 25.4 mm (1 inch) wide core laminate strip in each of the front, middle, and intermediate sections.

[0171] 4. Place the core (28) on the support platform (900) equipped with a 25.4 mm wide cutter (901) and align it with the cross-sectional line of the channel. Double-sided tape (902) can be used to hold the sample in place. The platform includes two grooves or gaps on each side of the area to be cut, allowing the cutter blade to penetrate the thickness of the core.

[0172] 5. Cut the core in the transverse direction to obtain a core material strip including at least one channel, and optionally check the width of the cut sample strip (target = 25.4 mm ± 2 mm).

[0173] 6. Repeat steps 4 and 5 above for the front and middle transverse lines to obtain a total of three bands representing the front, middle, and middle sections of the channel.

[0174] 7. The core laminate strips may include two (or more) channel bond portions per strip. In this case, use scissors to cut 25.4 mm wide (1 inch) strips in the longitudinal direction to obtain at least one channel sample (100, 102, 104) representing each segment, including the channel bond portion (27). If more than one channel exists per strip, note which channel each channel sample corresponds to (e.g., left or right channel). A channel-free flap (106) of at least 5 mm should be present between the channel bond portion (27) and the inner edge (108) of the sample to ensure proper manipulation of the sample – see Figure 10 If applicable, obtain samples of the left channel bond and the right channel bond. Appropriately label the cut channel bond samples, e.g., left channel / right channel.

[0175] 8. During testing, the samples will be clamped on their outer edges (114). The outer edges (114) of the samples can be trimmed with scissors; however, for testing purposes, the minimum distance (110) between the channel adhesive portion (27) of the sample and the outer edge (103) should be sufficient to ensure that the core-wrapping material is properly clamped into the fixture. Typically, for this purpose, the minimum distance (110) between the channel and the outer edge should be at least 5 mm, with 20 mm being ideal.

[0176] 9. Gently remove any absorbent material outside the channel adhesive between the top (45) and bottom (46) of the core wrapper. For this, if necessary, any longitudinal side seals of the core wrapper on the outer edge (114) of the sample may need to be opened (see [link to sample description]). Figure 11 ).

[0177] Test Procedure (see) Figure 12 ) :

[0178] Set up the test instrument in an area where the temperature is kept constant at 23°C, and ensure that the test instrument has at least 2 hours to reach that temperature.

[0179] 1. Clamp the outer edge (114') of the sample bottom layer (46) into the clamp of the large adhesive (120) chuck that is suspended at the top of the tester rod.

[0180] 2. Clamp another adhesive clamp (medium) (121) at its outer edge (114) to the top layer (45) of the core wrapper. The inner edge (108) of the sample faces away from the experimenter.

[0181] 3. Gently attach the 150g weight (122) to the medium-sized adhesive clamp and gently lower the clamped weight until it hangs freely over the test sample. Avoid any possible sudden drop of the weight.

[0182] 4. Once the weights are released, immediately press the timer reset button to start the timer from 0 minutes. Note: The timer must be checked to ensure it has started counting from 0.0 min. The operator should observe the numbers change from 0.0 min to 0.1 min.

[0183] 5. Repeat the above procedure for each prepared sample. The "test bench" allows for the testing of several samples in parallel.

[0184] 6. Once the sample weight falls onto the base plate due to breakage of the adhesive, the timer will stop. The base plate includes a switch connected to the timer so that the timer automatically stops when the weight falls. The recorded time is the "static peel force time" of the sample (in minutes). Note: If the weight falls due to the sample slipping out of the clamp (121) or due to tearing of the core wrapping but without breakage of the adhesive, a new sample needs to be tested again.

[0185] 7. If the sample weight has not fallen after 999 minutes, the static peel force time shall be reported as 999 minutes (maximum static peel force time).

[0186] 8. For a commercially available article of a given construction, repeat the measurement 10 times on an equivalent article (e.g., 10 randomly selected diapers from a commercially sourced diaper package) to obtain the average static peel force time for a given channel segment. If the absorbent core comprises two or more channels, the measurement can be performed individually for each of these channels. For example, if the core comprises a right channel and a left channel, the static peel force time for the right channel and the left channel are measured and reported separately.

[0187] Miscellaneous

[0188] As used herein, the terms “comprising” or “including” are open-ended terms; each specifies the presence of a subsequent feature, such as a component, but does not exclude the presence of other features, such as elements, steps, or components, known in the art or disclosed herein. These terms based on the verb “comprising” should be interpreted to cover the narrower term “substantially constitutes”, which excludes any unmentioned element, step, or component that significantly affects the manner in which the feature performs its function; and the broader term “consisting of”, which excludes any unspecified element, step, or component. Any preferred or exemplary embodiments described below do not limit the scope of the claims unless expressly stated otherwise. Words such as “usually,” “often,” “preferably,” “advantageously,” “particularly,” etc., also define the feature, but they are not intended to limit the scope of the claims unless expressly stated otherwise.

[0189] Unless otherwise specified, this specification and claims refer to absorbent cores and articles that have been conditioned for at least 24 hours prior to use (i.e., dry and without added fluid) at 23°C + / - 2°C and 50% + / - 5% relative humidity (RH).

[0190] The dimensions and values ​​disclosed herein should not be construed as strictly limited to the precise numerical values ​​cited. Rather, unless otherwise specified, each such dimension is intended to represent the stated value and the range surrounding its functional equivalent. For example, a dimension disclosed as “40 mm” is intended to represent “approximately 40 mm”.

Claims

1. A personal hygiene absorbent article (20) comprising a front waist area (36), a crotch area (37), a back waist area (38), a longitudinal centerline (80) extending in a longitudinal direction (y), and a length L measured along the longitudinal centerline, wherein the front waist area, the crotch area, and the back waist area have the same length as one-third of L as measured along the longitudinal centerline; The article includes a top sheet (24), a bottom sheet (25), and an absorbent core (28) located between the top sheet and the bottom sheet. The absorber core includes: Top layer of core encapsulation (45); Core wrapper bottom layer (46); An absorbent material layer (60) is located between the top layer and the bottom layer of the core wrapper, wherein the absorbent layer (60) has a length L' measured along the longitudinal centerline (80) in the longitudinal direction; and At least one elongated channel (26) without absorbent material, the channel having a front end (62) and a rear end (66) and a midpoint (64), wherein the midpoint is longitudinally equidistantly disposed between the front end and the rear end of the channel, wherein the midpoint (64) is present in the crotch area (37) of the article, and the channel has a length L" measured in the longitudinal direction (y), the length being at least 20% of L' and / or at least 12 cm; The channel includes a channel adhesive portion (27) located between the top layer (45) and the bottom layer (46) of the core wrapper. The channel includes a front section (100) surrounding or adjacent to the front end of the channel, a crotch section (100) surrounding or adjacent to the midpoint (64) of the channel, and an intermediate section (102) disposed between the front section and the crotch section. The adhesive strength in the front section (100) is higher than that in the middle section (102); and the adhesive strength in the crotch section (104) is higher than that in the middle section (102); wherein the adhesive strength of each section is measured in minutes according to the static peel force time test disclosed herein.

2. The absorbent article (20) according to claim 1, wherein the adhesive strength in the front section (100) is higher than the adhesive strength in the crotch section (104).

3. The article of any one of the preceding claims, wherein the channel length L" is in the range of 20% to 80% of the length L' of the absorption layer.

4. The article according to any one of the preceding claims, wherein the intermediate section (102) has an adhesive strength of at least 2 minutes, and in particular, wherein the intermediate section has an adhesive strength in the range of 2 minutes to 20 minutes.

5. The article according to any one of the preceding claims, wherein the adhesive strength of the front section is at least 20 minutes, particularly at least 30 minutes.

6. The article according to any one of the preceding claims, wherein the adhesive strength of the crotch section is at least 20 minutes, particularly at least 30 minutes.

7. The article according to any one of the preceding claims, wherein the adhesive strength of the front section is at least 10 minutes higher than the adhesive strength of the crotch section.

8. The article according to any one of the preceding claims, wherein the adhesive strength of the crotch section is at least 10 minutes higher than the adhesive strength of the intermediate section.

9. The article according to any one of the preceding claims, wherein the length L' of the absorbent layer is in the range of 50% to 100% of the length L of the article, and in particular, wherein L' is in the range of 60% to 90% of L.

10. The article according to any one of the preceding claims, wherein the channel adhesive (27) is at least partially formed by channel adhesive (70) between the top layer of the core wrapper and the bottom layer of the core wrapper, wherein the amount of adhesive per channel area varies in the different sections such that the front section and the crotch section of the channel each contain more channel adhesive than the middle section.

11. The article of manufacture according to the preceding claim, wherein the front section comprises more channel adhesive than the crotch section.

12. The article of claim 1, wherein the channel is not straight and parallel to the longitudinal direction at least between the front end (62) and the midpoint (64) of the channel, and the channel adhesive is an auxiliary adhesive (70) comprising a plurality of longitudinally oriented parallel strips (82, 84) separated by gaps (86, 88), wherein the strips have different widths and / or different gap widths, such that there is a different amount of auxiliary adhesive per channel area in the front section, the middle section and the crotch section of the channel.

13. The article according to the preceding claim, wherein the auxiliary adhesive (70) is applied to a channel region (74) that is wider in the transverse direction than the channel (26), and the auxiliary adhesive (70) at least partially secures the absorbent material within the core package, preferably wherein the auxiliary adhesive is also applied to a channel front region (72) of the core package disposed in the front portion of the channel, and optionally to a core rear region (76) disposed in the rear portion of the channel.

14. The article of claim 10, wherein the channel adhesive is applied as a spiral adhesive (77, 78, 79) in the front section (100) and the crotch section (102) with a higher basis weight than in the middle section (104), and optionally, wherein the basis weight of the spiral adhesive is higher in the front section (100) than in the crotch section (104), and in particular, wherein the channel (26s) is straight and parallel to the longitudinal direction at least between the front end (62) and the midpoint (64) of the channel (26).

15. The article of claim 10, wherein the channel adhesive portion is a hot melt adhesive portion formed by applying different pressures between the top layer of the core wrapper and the bottom layer of the core wrapper during the open time of the hot melt adhesive, such that varying adhesive strengths are obtained in the front section, the crotch section and the middle section of the channel.

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