Patent Application
20140296817
The present invention relates to a method and apparatus for manufacturing a sandwich structure consisting of a carrier layer, an auxiliary layer and absorbent particulate polymer material positioned there between. The method allows depositing absorbent particulate polymer material in a desired pre-determined pattern of clusters onto a moving carrier layer, adding an auxiliary layer and subsequently attaching the layers at least partially to each other to form a sandwich structure at high production speed and relative low cost. Such method is particularly useful in the manufacturing of absorbent structures to be used in absorbent articles, preferably disposable articles, such as for instance a feminine hygiene garment, baby diaper, baby pants and/or adult incontinence garment. As such the method allows manufacturing of absorbent structures without substantial use of cellulose fibres and/or chemical binders, and is thus considered to be very environmentally friendly.
There has been increasing demand in recent years for flexible, thinner, lightweight absorbent structures to resolve various problems of manufacturing, marketing, design, fit, wearing comfort, distribution, garbage disposal, material and energy consumption, transportation and storage costs and the like.
It is known from the art to introduce absorbent particulate polymer material into a matrix of cellulose fibers so as to create an absorbent structure whereby the absorbent particulate polymer material is capable of absorbing, distributing and retaining liquid while the cellulose fiber matrix acts as a grid, keeping absorbent particulate polymer material in its desired location. However, since the presence of cellulose fibers, usually wood pulp or fluff, results in relatively thick and bulky products, the process of manufacturing fluff involves cutting down trees and treating the wood pulp with various chemicals and transportation of the raw materials and end product is typically done over relative large distances, the product and process is considered to be less environmentally friendly. Hence here also there has been a desire to manufacture such absorbent structures without the use of wood pulp.
Many attempts have been undertaken to manufacture flexible, thin and lightweight absorbent structures, consisting of an absorbent material bonded to or in between one or more carrier layers. The physical and/or chemical interaction in between the absorbent material, the bonding material and/or the carrier layer often leads to a reduced absorption, distribution and/or retention performance despite functional and/or structural requirements.
It has been found that it is important to at least partially immobilise the absorbent particulate polymer material by compartmentalizing, restraining and/or bonding it to the absorbent structure in such a way that the absorbent structure is able to hold the absorbent particulate polymer material in either dry, partially and/or fully liquid loaded state. Failing to provide sufficient structural integrity however leads to poor fluid management resulting in loss of functional performance such as absorbent structure coherence, absorption, distribution, transport and/or retention performance and partial or overall failure.
In order to be able to keep absorbent particulate polymer material compartmentalized, restrained and/or bonded within the absorbent structures during usage, it is necessary to deposit such absorbent particulate polymer material in a predetermined and desired location, pattern during the manufacturing process. It is therefore very desirable to enable the depositing of absorbent particulate polymer material in a substantially continuously, specific, well-defined and discretely arranged pattern onto a carrier layer moving at a relatively high speed.
Multiple attempts have been made to provide methods to manufacture composite structures with selected regions of particulate materials intermittently and discretely located along the length of a carrier layer, whereby EP1621166 describes a process for forming a sandwich structure having a pattern of particulate material enveloped between a carrier and cover material. The method comprises the steps of providing an essentially flat carrier material and an essentially flat cover material for forming the outer sandwich layers. Further steps provide an essentially endless support means for the carrier material having a support pattern and a carrier material holding means. The carrier material is positioned over the support means at a carrier speed relative to a fixed frame, whereby the carrier means contacts the support pattern with its support surface and whereby the relative speed between carrier material and the contact surface of the carrier support means is essentially zero. An absorbent particulate material is provided and an amount of absorbent particulate material is pre-metered. The cover material and the carrier material are combined and affixed by a fixation means with the absorbent particulate material positioned there between. The carrier material is supported only in the region of the support pattern of the support means and deformed by a carrier holding means such that indentations are formed in the unsupported regions. The absorbent particulate material is fanned into the indentations of the carrier material; thereby forming a pattern of particulate material which is sandwiched in between the outer layers.
Whilst the prior art attempts describe approaches to manufacture sandwich structures and mechanisms to obtain discrete particulate material clusters within pockets, it is believed that the above methods suffer from one or more drawbacks. The prior art methods lack accuracy and repeatability of the absorbent particulate material patterns and have unbalanced pre-metering, forming and transport means. The large and expensive pre-metering, forming and suction means required for the particulate material transport and clustering require very specific customization for each product concept/size/absorbency and are very expensive to design, build, install and replace. These apparatus are furthermore consuming a relative high amount of energy and take significant resources to operate during normal production. The web materials furthermore require operating within very narrow tolerances in relation to particle material clustering and depositing and can only operate under relatively limited production speeds, demanding large and complex machinery and installations which are subject to excessive tear, wear, maintenance, cleaning, adjustment, etc. The immobilisation and/or fixation means in prior art products also involve using chemical adhesives, glues or binders, which have a negative impact on the environment and add extra cost to the process. Also, the prior art methods require the carrier layer to be at least sufficiently gas permeable, whilst it would be desired for many applications in fluid handling and storing products such as e.g. baby diapers that the carrier layer would be composed of a liquid and substantially gas impervious barrier layer. Such inefficient and ineffective methods and the complex manufacturing processes makes neither of the prior art methods economically, technically and/or environmentally advantageous.
Hence, there is still a need in the art for a reliable, environmentally-friendly, cost-efficient and maintenance-friendly method and apparatus to consistently dispose and pocket particulate materials continuously in a specific, well-defined and discretely arranged pattern on the surface of a carrier layer which moves at a high production speed with limited consumption and/or wastage of resources during the production process.
As a result of exhaustive research to address the above-identified and related problems, the inventors have found a more favorable and advantageous manufacturing process to obtain such concepts and structures, which will be explained in greater detail down below.
The present invention relates to a method for manufacturing a composite structure having a particulate material, preferably an absorbent particulate polymer material, deposited in a predefined and desired pattern onto a carrier layer so as to form substantially cellulose free and substantially glue free absorbent structures.
In particular, the present invention provides a method for producing a sandwich structure comprising a pattern of particulate material, said method comprising the steps of:
The method comprises the steps of providing an essentially endless carrier layer in a particulate material deposit position in close proximity to a clustering means. In a preferred embodiment of the invention the clustering means with desired perforation pattern are incorporated into an essentially endless rotating drum, the clustering means can be mounted replaceably onto the rotating drum or can be unitary therewith. The carrier layer is positioned over a substantially endless support means at a carrier speed relative to a fixed frame, whereby the carrier layer is in contact with the support means and whereby the relative speed between carrier layer, the support means and the clustering means and/or drum is preferably essentially zero. Alternatively the cluster means are stationary and the relative speed between the carrier layer and the cluster means is different from zero, however this is not preferred. A particulate material is provided by a particulate material supply means and the particulate material stream is directed towards the clustering means. The particulate material is collected by the inlet regions of the perforations of the clustering means and at least held partially in the outlet region and/or inlet region of the perforations of the clustering means until evacuated. The carrier layer is preferably supported over at least part of the support means surface area while particulate material caught and held in the perforations is deposited onto the carrier material.
In an embodiment according to the invention, the resulting composite structure of a carrier layer with discretely deposited particulate material clusters thereon, is complemented with an auxiliary layer, such as for instance non-woven, tissue, paper, thermoplastic material and the like and/or affixed by attachment means, such as for instance glue, bonds, joints and the like, with the particulate material clusters relatively immobilized there between so as to obtain a sandwich structure usable in the form of an absorbent structure.
In a preferred embodiment the auxiliary layer immobilizes and/or restrains the particulate material clusters and/or the attachment means seal, bond and/or join the outer layers together via ultrasonic bonding, thermo-bonding, and/or pressure-bonding means. The attachment means preferably form and/or define pockets and/or compartments of particulate material clusters, whereby the bonding and/or joint regions comprise essentially no particulate material and/or glue. For economic, environmental and technical reasons the particulate material clusters are preferably not intentionally covered with substantial amounts of thermoplastic materials, glues, binders and/or adhesives to fixate, pocket, encapsulate, bind and/or join these particulate material clusters to one or more outer layers, but the particulate material clusters are preferably pocketed by providing an attachment pattern in between the outer-layers by way of attachment means such as ultrasonic bonding means.
Additional materials and/or layers may be provided to provide extra functional and/or structural advantages such as strength, acquisition, absorption, distribution, transport, retention, etc. may be incorporated. For instance liquid permeable distribution layers and/or liquid impermeable wicking layers can be added to or be unitary with the absorbent structure.
Another aspect of the present invention provides an apparatus for producing a composite structure comprising particulate material clusters, said apparatus comprising:
The invention also provides an apparatus for forming a composite structure having predetermined and selected particulate material clusters deposited on a carrier layer. The apparatus comprises a clustering means having perforations comprising inlet regions and outlet regions, and a particulate material supplying means providing particulate materials to the clustering means. The carrier layer supplying means provides a carrier layer, while the support means move the carrier layer into depositing position close to the outlet regions of the clustering means. The clustering means are preferably arranged to catch, collect and hold the particulate materials from the particulate material stream as provided by the particulate supply means. The perforations within the clustering means are designed so as to catch and collect the particulate material stream by way of the inlet regions, and preferably converge the particulate materials towards the outlet regions so as to accumulate and build up particulate material clusters within the perforations ready for deposit onto the carrier layer in preferably discrete printing patterns of particulate material clusters. The support means brings the carrier layer into a depositing position of, preferably in close proximity to, most preferably in contact with, the outlet regions of perforations of the clustering means. Preferably a selected level of pressure contact in between the deposit surface of the carrier layer and the outer contact surface of the clustering means is provided, so as to lock the discrete particulate material clusters until deposited onto the deposit surface of the carrier layer. In an alternative embodiment, no substantial pressure contact in between the deposit surface of the carrier layer and the outer contact surface of the clustering means is provided, and the particulate material provided via the particulate material stream is immediately caught, collected and deposited upon the carrier layer. This is typically used in case of stationary clustering means versus the moving carrier layer. After deposit the transport means moves the carrier layer and the particulate materials deposited thereon away from the clustering means. In a preferred embodiment the particulate material clusters deposited onto the carrier layer are covered by an auxiliary layer via a covering means so as to form for instance an absorbent polymer material area. In a more preferred embodiment, the particulate material clusters from the composite structure are relatively immobilised, bound, joined and/or otherwise restrained in between a carrier layer and any suitable auxiliary layer. Preferably, attachment means leading to a composite sandwich structure of a carrier layer and auxiliary layer with particulate materials enclosed and/or immobilised, bound, join and/or restrained there between in the form of compartment or clusters are provided.
In a preferred embodiment, the particulate material supply means comprises a vibrating, coiling and/or turning means so as to accurately, continuously and controllably provide the required particulate material amounts, sizes and/or speeds towards the clustering means. It is furthermore preferred, that the particulate material is being transported in between such vibrating, coiling and/or turning means and the clustering means by way of a feeding tube means, which can alternatively be arranged with gas pressure means to guide and direct the particulate material stream to the inlet regions of the clustering means. In a preferred embodiment, the feeding tube is substantially longitudinal, vertically and/or converging and the particulate material has a substantial weight so that one can use gravity to transport the particles through the feeding tube into the clustering means. However, additional conveyer means such as mechanical (such as airflows), electro-static (such as particle material charging) or electro-magnetic (such as magnets in case the particles interact with a magnetic field) and/or other means can be used to convey and/or help convey such particulate material stream towards the clustering means.
In a preferred embodiment, a dosing means of a volumetric, gravimetric or other type so as to control the quantity, size and/or speed of particles entering the feeding tube means is provided. It is further preferred that the particulate material stream can be redirected via the control means into removing means so as to be moved again towards the particulate supply means via recovery tubing means for re-use and/or less preferably guided out of the production system via collection means to be moved towards separate storage facilities for later usage and/or disposal in case irreparably damaged, contaminated, spoiled and/or rendered unusable.
In a preferred embodiment, the clustering means are unitary with a substantially endless rotating drum, preferably having a cylinder-like outer shell. In a preferred embodiment an endless rotating drum with replaceable, customisable and/or adjustable clustering means is provided. The drum is running in line with the opening of the feeding tube means thereby directing the particulate materials to fall, be guided, directed, pushed and/or vacuumed through the respective inlet regions and/or outlet regions of the perforation pattern of the clustering means to obtain the desired printing pattern.
It is preferred to under-fill (or, eventually ‘right-fill’) the perforations of the clustering means. Using a particle material supply means with a preferably gravimetric dosing system in combination with a feeding tube means such as a tube, pipe or conveyer of the right dimensions and shape will then ensure that the proper weights are supplied, gathered in the perforations and deposited by the outlet regions so as to form the desired printing pattern of particulate material clusters as stipulated by the perforation pattern of the clustering means.
In a preferred embodiment, the inlet regions are of a funnel-like shape with steep slopes separated from one another by sharp ridges so no substantial amounts of particulate materials remain caught in between the inlet regions and/or on the slopes of the inlet regions, but are readily transported towards the outlet regions for scheduled deposit on the carrier material. In a preferred embodiment, a combination of larger and smaller inlet regions and outer regions are provided leading to homogenous, heterogeneous or complex perforation patterns.
Preferably the void volume of the perforations is larger than the volumes of particulate material one wants to print, to prevent overfilling of the clustering means during the production process. In case of correctly designed clustering means and a fully, effectively and efficiently working apparatus one can also greatly increase accuracy and reliability of the manufacturing process and thereby also eliminate the need for a sweeping means, thus optimising raw material usage, limiting investment cost and reducing maintenance cost. However in case required, any ‘overfill’, migration and/or misplacement of particulate material can be guided and/or redirected via sweeping means, such as scrapers, brushes, air blow, vacuum suction, etc, into one or more available inlet regions of the cluster means and/or be guided into recovery means or collection means so as to be moved away from the clustering means for re-use, collection and/or disposal.
The method and apparatus according to a preferred embodiment of the invention leads to highly appreciated thin, flexible and/or light-weight composite structure which are economically, environmentally, technically and/or commercially advantageous, not in the least since they are obtained without substantial and bulky amounts of fibrous absorbent materials such as fluff and wood pulp (cfr “fluffless”) and are not using substantial and expensive amounts of glue, binder, adhesive and/or other thermoplastic materials (cfr “glueless”). This has so far been unprecedented within the prior art and is highly preferred by industry, society and consumers.
The present invention relates to a method and apparatus for creating composite structures comprising particulate material, preferably absorbent particulate material such as absorbent polymer materials, more preferably absorbent particulate polymer material; preferably clustered, enveloped and/or immobilised in between a carrier layer and auxiliary layer, possibly via attachment means, so as to form discrete and predetermined printing patterns of particulate material sheets for use in absorbent products, preferably a disposable absorbent article from the personal hygiene industry, such as feminine hygiene garments, baby diapers and pants and adult incontinence garments.
Unless otherwise defined, all terms used in disclosing the invention, including technical and scientific terms, have the meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. By means of further guidance, term definitions are included to better appreciate the teaching of the present invention.
As used herein, the following terms have the following meanings:
“A”, “an”, and “the” as used herein refers to both singular and plural referents unless the context clearly dictates otherwise. By way of example, “a compartment” refers to one or more than one compartment.
“About” as used herein referring to a measurable value such as a parameter, an amount, a temporal duration, and the like, is meant to encompass variations of +/−20% or less, preferably +/−10% or less, more preferably +/−5% or less, even more preferably +/−1% or less, and still more preferably +/−0.1% or less of and from the specified value, insofar such variations are appropriate to perform in the disclosed invention. However, it is to be understood that the value to which the modifier “about” refers is itself also specifically disclosed.
“Absorbent article”, “absorbent garment”, “absorbent product”, “absorbing article”, “absorbing garment”, “absorbing product” and the like as used herein are used interchangeably and refer to devices that absorb and contain bodily exudates, and more specifically, refers to devices that are placed against or in proximity to the body of the wearer to absorb and contain the various liquids discharged from the body. Absorbent articles include but are not limited to feminine hygiene garments, baby diapers and pants, adult incontinence garments, various diaper and pants holders, liners, towels, absorbent inserts and the like.
“Absorbent component” as used herein refers to a structural constituent of an absorbent structure, e.g., a piece of an absorbent core, such as one of multiple pieces in a multi-piece absorbent core.
“Absorbent element” as used herein refers to a part of a functional constituent of an absorbent structure, e.g., a liquid acquisition layer, a liquid distribution layer, or a liquid storage layer formed of a material or materials having particular liquid handling characteristics suitable for the specific function.
“Absorbent insert” as used herein refers to a device adapted for insertion into an absorbent article and to serve as an absorbent structure when so inserted.
“Absorbent layer” as used herein refers to a term referring to a discrete, identifiable sheet-like or web-like element of an absorbent structure which may remain detached and relatively movable with respect to another such element or may be attached or joined so as to remain permanently associated with another such element. Each absorbent layer may itself include a laminate or combination of several layers, sheets and/or webs of similar or diverse compositions.
“Absorbent polymer material”, “absorbent gelling material”, “AGM”, “superabsorbent”, “superabsorbent material”, “super absorbent polymer”, “SAP” and the like as used herein are used interchangeably and refer to any suitable particulate (e.g., flaked, particulate, granular, or powdered) or fibrous cross linked polymeric materials that can absorb at least 5 times and preferably at least about 10 times or more its weight of an aqueous 0.9% saline solution as measured using the Centrifuge Retention Capacity test (EDANA 441.2-01).
“Absorbent polymer material area” as used herein refers to the area of the absorbent structure wherein adjacent layers are separated by a multiplicity of absorbent polymer material. Incidental contact areas between these adjacent layers within the absorbent particulate polymer material area may be intentional (e.g. bond area's) or unintentional (e.g. manufacturing artefacts).
“Absorbent particulate polymer material” as used herein refers to an absorbent polymer material which is in particulate form such as powders, granules, flakes and the like so as to be flowable in the dry state.
“Absorbent structure” as used herein refers to those elements of an absorbent article comprising material or a combination of materials suitable to absorb, distribute and retain bodily exudates.
“Absorption” as used herein refers to the process by which a liquid is taken up within a material.
“Acquisition layer”, “acquisition region”, “acquisition surface” or “acquisition material” and the like as used herein refer to a layer having a faster liquid uptake capability.
“Absorbency” is the ability of a material to take up fluids by various means including capillary, osmotic, solvent, chemical or other action.
“Adult incontinence garment” as used herein refers to absorbent articles intended to be worn by incontinent adults, for absorbing and containing bodily exudates.
“Adhesion” as used herein refers to the force that holds different materials together at their interface.
“Adhesive” as used herein refers to a material, which may or may not be flowable in solution or when heated, that is used to bond materials together.
“Adsorption” as used herein refers to the process by which a liquid is taken up by the surface of a material.
“Air laying” as used herein refers to forming a web by dispersing fibres or particles in an air stream and condensing them from the air stream onto a moving screen by means of a pressure or vacuum; a web of fibres produced by air laying is herein referred to an “airlaid”; an airlaid web bonded by one or more techniques to provide fabric integrity is herein referred to an “airlaid non-woven”.
“Apparent density”, “density” and like as used herein refers to the basis weight of the sample divided by the calliper with appropriate unit conversions incorporated therein. Apparent density used herein has the unit g/cm3.
“Attach”, “attached” and “attachment” as used herein are synonymous with their counterparts of the terms “fasten”, “affix”, “secure”, “glue”, “bind”, “join” and “link”.
“Baby diaper” as used herein refers to absorbent articles intended to be worn by children, for absorbing and containing bodily exudates which the user draws up between the legs and fastens about the waist of the wearer.
“Baby pants” as used herein refers to absorbent articles marketed for use in transitioning children from diapers to underwear intended to cover the lower torso of children, so as to absorb and contain body exudates which article is generally configured like a panty garment and manufactured with a completed waist encircling portion, thereby eliminating the need for the user to fasten the article about the waist of the wearer.
“Back region” as used herein refers to the portion of an absorbent article or part thereof that is intended to be positioned proximate the back of a wearer.
“Backing” as used herein refers to a web or other material that supports and reinforces the back of a product.
“Basis weight” is the weight per unit area of a sample reported in grams per square meter, g/m2 or gsm.
“Bodily exudates”, “body exudates”, “bodily fluids”, “body fluids”, “bodily discharges”, “body discharges”, “liquids” and the like as used herein are used interchangeably and refer to, but are not limited to urine, blood, vaginal discharges, breast milk, sweats and faecal matter.
“Binder”, “adhesive”, “glue”, “resins”, “plastics” and the like as used herein are used interchangeably and refer to substances, generally in a solid form (e.g. powder, film, fibre) or as a foam, or in a liquid form (e.g. emulsion, dispersion, solution) used for example by way of impregnation, spraying, printing, foam application and the like used for attaching or bonding functional and/or structural components, elements and materials, for example including heat and/or pressure sensitive adhesives, hot-melts, heat activated adhesives, thermoplastic materials, chemical activated adhesives/solvents, curable materials and the like.
“Bond strength” as used herein refers to the amount of adhesion between bonded surfaces. It is a measure of the stress required to separate a layer of material from the base to which it is bonded.
“Capillary action”, “capillarity”, or “capillary motion” and the like as used herein are used to refer to the phenomena of the flow of liquid through porous media.
“Chassis” as used herein refers to a foundational constituent of an absorbent article upon which the remainder of the structure of the article is built up or overlaid, e.g., in a diaper, the structural elements that give the diaper the form of briefs or pants when configured for wearing, such as a backsheet, a topsheet, or a combination of a topsheet and a backsheet.
“Cellulose fibres” as used herein refers to naturally occurring fibres based on cellulose, such as, for example cotton, linen, etc; wood pulp fibres are one example of cellulose fibres; man-made fibres derived from cellulose, such as regenerated cellulose (rayon), or partially or fully acetylated cellulose derivatives (e.g. cellulose acetate or triacetate) are also considered as cellulose fibres.
“Cluster” or the like as used herein refers to an agglomeration of particles and/or fibres.
“Chemically stiffened fibres”, chemically modified fibres”, “chemically cross-linked fibres”, “curly fibres” and the like as used herein are used interchangeably and refer to any fibres which have been stiffened by chemical means to increase stiffness of the fibres under both dry and aqueous conditions, for example by way of addition of chemical stiffening agents (e.g. by coating, impregnating, etc), altering the chemical structure of the fibres themselves (e.g. by cross-linking polymer chains, etc) and the like.
“Cohesion” as used herein refers to the resistance of similar materials to be separated from each other.
“Comprise,” “comprising,” and “comprises” and “comprised of” as used herein are synonymous with “include”, “including”, “includes” or “contain”, “containing”, “contains” and are inclusive or open-ended terms that specify the presence of what follows e.g. a component and do not exclude or preclude the presence of additional, non-recited components, features, elements, members, steps, known in the art or disclosed therein.
“Coverstock” as used herein refers to a lightweight non-woven material used to contain and conceal an underlying absorbent core material; examples are the facing layer or materials that cover the absorbent cores of feminine hygiene garments, baby diapers and pants and adult incontinence garments.
“Crotch region” of an absorbent article as used herein refers to about 50% of the absorbent article's total length (i.e., in the y-dimension), where the crotch point is located in the longitudinal centre of the crotch region. That is, the crotch region is determined by first locating the crotch point of the absorbent article, and then measuring forward and backward a distance of 25% of the absorbent article's total length.
“Cross direction (CD)”, “lateral” or “transverse” and the like as used herein are used interchangeably and refer to a direction which is orthogonal to the longitudinal direction and includes directions within ±45° of the transversal direction.
“Curing” as used herein refers to a process by which resins, binders or plastics are set into or onto fabrics, usually by heating, to cause them to stay in place; the setting may occur by removing solvent or by cross-linking so as to make them insoluble.
“Diaper”, “conventional diaper”, “diaper-like”, “diaper-like garment” and the like as used herein are used interchangeably and refer to disposable absorbent articles, which typically include a front waist portion and a back waist portion which may be releasably connected about the hips of the wearer during use by conventional fasteners such as adhesive tape fasteners or hook and loop type fasteners. In use, the article is positioned between the legs of the wearer and the fasteners are releasably attached to secure the back waist portion to the front waist portion of the diaper, thereby securing the diaper about the waist of the wearer. The front waist portion and a back waist portion are connected by relatively non-stretchable or stretchable members (the term “stretchable” as used herein refers to materials that are extensible when forces are applied to the material, and offer some resistance to extension). Hence, such articles are generally not configured to be pulled up or down over the hips of the wearer when the fasteners are attached.
“Disposable” is used herein to describe articles that are generally not intended to be laundered or otherwise restored or reused (i.e., they are intended to be discarded after a single use and, preferably, to be recycled, composted or otherwise disposed of in an environmentally compatible manner).
“Distribution layer” and the like as used herein are used interchangeably and refer to a permeable layer having a capacity in internal transporting, dispersing and distributing liquids.
“Dry laying” as used herein refers to a process for making a non-woven web from dry fibre; these terms apply to the formation of carded webs, as well as to the air laying formation of random webs; a web of fibres produced by dry laying is herein referred to as a “drylaid”; a drylaid web bonded by one or more techniques to provide fabric integrity is herein referred to a “drylaid non-woven”.
“Dry strength” as used herein refers to the strength of a joint determined in dry state conditions, immediately after drying under specified conditions or after a period of conditioning in the standard laboratory atmosphere.
“Fabric” as used herein refers to a sheet structure made from fibres, filaments and/or yarns.
“Feminine hygiene garments” as used herein refer to absorbent hygiene articles intended to be worn by woman, for absorbing and containing body exudates.
“Fibre” as used herein refers to the basic threadlike structure from which non-woven, yarns and textiles are made. It differs from a particle by having a length at least 4 times its width; “Natural fibres” are either of animal (wool, silk), vegetable (cotton, flax, jute) or mineral (asbestos) origin, while “Man-made fibres” may be either polymers synthesised from chemical compounds (polyester, polypropylene, nylon, acrylic etc.) or modified natural polymers (rayon, acetate) or mineral (glass). “Fibre” and “filament” are used interchangeably.
“Film”, “foil” and the like as used herein are used interchangeably and refer to a thin sheet of essentially non-absorbent material such as plastic or closed foams. In this invention it particularly refers to materials that do not correspond to non-woven.
“Fluff pulp” as used herein refers to wood pulp specially prepared to be dry laid.
“Front region” as used herein refers to the portion of an absorbent article or part thereof that is intended to be positioned proximate the front of a wearer.
“Garment facing layer” as used herein refers to elements of the chassis that form the outer surface of the absorbent article, such as the back sheet, the side panels, the waist fasteners, and the like, when such elements are present.
“Heat activated adhesive” as used herein refers to a dry adhesive that is rendered tacky or fluid by application of heat or heat and pressure to the assembly.
“Heat sealing adhesive” as used herein refers to a thermoplastic adhesive which is melted between the adherent surfaces by heat application to one or both of the adjacent adherent surfaces.
“Highloft” as used herein refers to general term of low density, thick or bulky fabrics.
“Hot-melt adhesive” as used herein refers to a solid material that melts quickly upon heating, then sets to a firm bond upon cooling; used for almost instantaneous bonding.
“Hydrophilic” as used herein refers to having an affinity for being wetted by water or for absorbing water.
“Hydrophobic” as used herein refers to lacking the affinity for being wetted by water or for absorbing water.
“Immobilisation layer” as used herein refers to a layer able to be applied to the particulate material with the intent to immobilize, bond, join and/or restrain particulate material.
“Join”, “joined” and “joining” as used herein refers to encompassing configurations wherein an element is directly secured to another element by affixing the element directly to the other element, as well as configurations wherein the element is indirectly secured to the other element by affixing the element to an intermediate member or members which in turn is or are affixed to the other element.
“Knitting” as used herein refers to the technique for interlocking loops of fibres with needles or similar devices.
“Layer” refers to identifiable components of the absorbent article, and any part referred to as a “layer” may actually comprise a laminate or combination of several sheets or webs of the requisite type of materials. As used herein, the term “layer” includes the terms “layers” and “layered.” “Upper” refers to the layer of the absorbent article which is nearest to and faces the wearer facing layer; conversely, the term “lower” refers to the layer of the absorbent article which is nearest to and faces the garment facing layer. “Layer” is three dimensional structure with a x dimension width, y dimension length, and z-dimensions thickness or calliper, said x-y dimensions being substantially in the plane of the article, however it should be noted that the various members, layers, and structures of absorbent articles according to the present invention may or may not be generally planar in nature, and may be shaped or profiled in any desired configuration.
“Machine direction (MD)”, “longitudinal” and the like as used herein are used interchangeably and refer to a direction running parallel to the maximum linear dimension of the structure and includes directions within ±45° of the longitudinal direction.
“Major surface” as used herein refers to a term used to describe the surfaces of greatest extent of a generally planar or sheet-like structural element and to distinguish these surfaces from the minor surfaces of the end edges and the side edges, i.e., in an element having a length, a width, and a thickness, the thickness being the smallest of the three dimensions, the major surfaces are those defined by the length and the width and thus having the greatest extent.
“Mass flow” as used herein refers to the flow of a liquid from one absorbent element or component to another absorbent element or component by channel flow action.
“Mechanical bonding” as used herein refers to a method of bonding fibres by entangling them. This can be achieved by needling, stitching with fibres or by the use of high-pressure air or water jets and the like.
“Non-woven” as used herein refers to manufactured sheet, web or batt of directionally or randomly orientated fibres, bonded by friction, and/or cohesion and/or adhesion, excluding paper and products which are woven, knitted, tufted, stitch-bonded incorporating binding yarns or filaments, or felted by wet-milling, whether or not additionally needled. The fibres may be of natural or man-made origin and may be staple or continuous filaments or be formed in situ. Commercially available fibres have diameters ranging from less than about 0.001 mm to more than about 0.2 mm and they come in several different forms: short fibres (known as staple, or chopped), continuous single fibres (filaments or monofilaments), untwisted bundles of continuous filaments (tow), and twisted bundles of continuous filaments (yarn). Non-woven fabrics can be formed by many processes such as melt blowing, spun bonding, solvent spinning, electro spinning, and carding. The basis weight of non-woven fabrics is usually expressed in grams per square meter (gsm).
“Pant”, “training pant”, “closed diapers”, “prefastened diapers”, “pull-on diapers” and “diaper-pants” and the like as used herein are used interchangeably and refer to absorbent articles which are typically applied to the wearer by first leading the feet into the respective leg openings and subsequently pulling the pants from the feet to waist area over the hips and buttocks of the wearer and which are capable of being pulled up or down over the hips of the wearer. Typically, such articles may include a front waist portion and a back waist portion which may be connected about the hips of the wearer by integral or releasable members. A pant may be preformed by any suitable technique including, but not limited to, joining together portions of the article using refastenable and/or non-refastenable bonds (e.g., seam, weld, adhesive, cohesive bond, fastener, etc.). A pant may be preformed anywhere along the circumference of the article (e.g., side fastened, front waist fastened).
“Polymer” as used herein refers to but is not limited to, homopolymers, copolymers, such as for example, block, graft, random and alternating copolymers, terpolymers, etc. and blends and modifications thereof. Unless otherwise specifically limited, the term “polymer” includes all possible spatial configurations of the molecule and include, but are not limited to isotactic, syndiotactic and random symmetries.
“Rear” as used herein refers to the portion of an absorbent article or part thereof that is intended to be positioned proximate the back of the wearer.
“Resin” as used herein refers to a solid or semisolid polymeric material.
“Substantially cellulose free” as used herein refers to an absorbent article, structure or core, that contains less than 20% by weight cellulosic fibres, less than 10% cellulosic fibres, less than 5% cellulosic fibres, no cellulosic fibres, or no more than an immaterial amount of cellulosic fibres which does not materially affect the thinness, flexibility or absorbency thereof.
“Thermobonding” as used herein refers to a method of bonding fibres by the use of heat and/or high-pressure.
“Thermoplastic” as used herein refers to polymeric materials that have a melting temperature and can flow or be formed into desired shapes on the application of heat at or below the melting point.
“Ultrasonic” as used herein refers to the use of high frequency sound to generate localised heat through vibration thereby causing thermoplastic fibres to bond to one another.
“Water-absorbing”, “liquid-absorbing”, “absorbent”, “absorbing” and the like as used herein are used interchangeably and refer to compounds, materials, products that absorb at least water, but typically also other aqueous fluids and typically other parts of bodily exudates such as at least urine or blood.
“Wearer facing layer” as used herein refers to elements of the chassis that form the inner surface of the absorbent article, such as the topsheet, the leg cuffs, and the side panels, etc., when such elements are present.
“Weaving” as used herein refers to the process of interlacing two or more sets of yarns at right angles to form a fabric; a web of fibres produced by weaving is herein referred to as a “Woven”.
“Web material” as used herein refers to an essentially endless material in one direction, i.e. the longitudinal extension or the length, or the x-direction in Cartesian coordinates relative to the web material. Included in this term is an essentially unlimited sequence of pieces cut or otherwise separated from an essentially endless material. Often, though not necessarily, the web materials will have a thickness dimension (i.e. the z-direction) which is significantly smaller than the longitudinal extension (i.e. in x-direction). Typically, the width of web materials (the y-direction) will be significantly larger than the thickness, but less than the length. Often, though not necessarily, the thickness and the width of such materials is essentially constant along the length of the web. Without intending any limitation, such web materials may be cellulosic fibre materials, tissues, woven or non-woven materials and the like. Typically, though not necessarily, web materials are supplied in roll form, or on spools, or in a folded state in boxes. The individual deliveries may then be spliced together to form the essentially endless structure.
A web material may be composed of several web materials, such as multilayer non-woven, coated tissues, non woven/film laminates. Web materials may comprise other materials, such as added binding material, particles, hydrophilizing agents and the like.
“Wet burst strength” is a measure of a layer's ability to absorb energy, when wet and subjected to deformation normal to the plane of the web.
“Wet strength” as used herein refers to the strength of a joint determined immediately after removal from a liquid in which it has been immersed under specified conditions of time, temperature and pressure. The term is commonly used in the art to designate strength after immersion in water.
“Wet laying” as used herein refers to the forming a web from an aqueous dispersion of fibres by applying modified paper making techniques; a web of fibres produced by wetlaying is herein referred to as a “wetlaid”.
“Wicking layer” and the like as used herein are used interchangeably and refer to a substantially impermeable layer having a larger capacity of superficial transporting, dispersing and distributing liquids.
“Wood pulp” as used herein refers to cellulosic fibres used to make viscose rayon, paper and the absorbent cores of products such as feminine hygiene garments, baby diapers and pants and adult incontinence garments.
“X-y dimension” as used herein refers to the plane orthogonal to the thickness of the article, structure or element. The x- and y-dimensions correspond generally to the width and length, respectively, of the article, structure or element.
“Z-dimension” as used herein refers to the dimension orthogonal to the length and width of the article, structure or element. The z-dimension corresponds generally to the thickness of the article, structure or element.
The recitation of numerical ranges by endpoints includes all numbers and fractions subsumed within that range, as well as the recited endpoints. Unless otherwise defined, all terms used in disclosing the invention, including technical and scientific terms, have the meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. By means of further guidance, term definitions are included to better appreciate the teaching of the present invention.
Upon review of the Detailed Description of the Invention and the accompanying Drawings provided herein, it will be apparent to one of ordinary skill in the art that the method and apparatus according to the present invention may be used to obtain composite structures, absorbent structures which may be used in absorbent articles, and more particularly, in disposable absorbent articles, such as feminine hygiene garments, baby diapers and pants and adult incontinence garments. Accordingly, the present invention shall not be limited to the method, apparatus, absorbent structures and absorbent articles specifically described and illustrated herein, although the following description is particularly directed to manufacture of composite structures and absorbent structure for absorbent disposable baby diaper products.
The present invention was based upon the findings that products resulting from a method and apparatus to create a composite structure comprising particulate material deposited in a pre-designed and desired pattern, can be more efficiently used to absorb, distribute and retain liquid. Absorbent articles, such as feminine hygiene garments, baby diapers and pants and adult incontinence garments absorb, distribute, transport and contain bodily exudates. They also are intended to prevent bodily exudates from leaking, soiling, wetting or otherwise contaminating clothing or other articles, such as bedding, that come in contact with the wearer. A disposable absorbent article, such as a disposable diaper, may be worn for several hours in a dry state or in bodily exudates loaded state. Accordingly, efforts have been made toward improving the fit and comfort of the absorbent article to the wearer, both when the article is dry and when the article is fully or partially loaded with body exudates, while maintaining or enhancing the absorbing and containing functions of the article.
Some absorbent articles, like diapers, contain a particulate material, such as an absorbent polymer material, more preferably an absorbent particulate polymer material. Such absorbent particulate material absorbs liquid and swells, and it is actually more effective when disposed in an absorbent structure in a certain pattern or arrangement when intending optimal absorbency, fit and/or comfort. Since it is desirable for absorbent particulate material to remain in its intended location in an absorbent article, such particulate materials are to be clustered and are desirably relatively immobilized in the absorbent article such that the absorbent particulate material remains immobilized, bonded, joined and/or restrained on their intended location when the absorbent article is dry, partially wetted and/or fully wetted.
In addition to being absorbent, absorbent articles, such as diapers, may desirably also be thin, flexible and/or light-weight, for ease and comfort in use and for more convenient and neat packaging and storage. Absorbent articles, which may often be used in large quantities, may also desirably be inexpensive. Some technologies of clustering and immobilizing absorbent particulate polymer material in an absorbent article such as additional fluff, add bulk to the absorbent article and thereby increase thickness, reduce flexibility, and/or increase cost of the absorbent article. Other technologies for immobilizing absorbent particulate polymer material in an absorbent article may not be as effective in maintaining immobilization when the absorbent article is in the wet state as compared to the dry state. Accordingly, there remains a need for a method and apparatus which can dose the absorbent particulate material in specified quantities, cluster it in desired particulate material clusters and deposit and position it in a desired pattern so that thin, flexible, and/or inexpensive absorbent article can be obtained.
With reference to
The clustering means 250 includes a pattern of perforations 304, preferably in the form inlet regions 304a joined to outlet regions 304b, and are arranged to form and provide a desired printing pattern 320 of particulate material clusters 703 onto the carrier layer 401. The support means 600 is preferably in substantial contact with the support surface 412 of the carrier layer 401. The support means 600 preferably ensures a close enough connection in between the deposit surface 411 of the carrier layer 401 and the outlet regions 304b to prevent unwanted migration of the particulate materials 201 from the carrier deposit zones 415 to the carrier inter-deposit zones 416. Although not required to work the current invention, it is highly recommended to foresee a close pressure contact connection in between the deposit surface 411 of the carrier layer 401 and the outlets regions 304b and inter-outlet zones 309 of the clustering means 250 to prevent unwanted migration and/or shifting of the particulate materials 201 from the carrier deposit zones 415 towards the carrier inter-deposit zones 416. The close deposit contact ensures favourable deposit and printing of particulate material 201 onto the deposit surface 411 of the carrier layer 401 without substantially loss of material.
The resultant printing pattern 320 forms desired and substantially spaced-apart particulate material clusters 703, preferable without any substantial amounts of particulate materials 201 in between the particulate material clusters 703. A covering means 500 provides an auxiliary layer 501, such as for instance a liquid-permeable fibrous web such as a non-woven, paper, tissue, woven, fabric, web, perforated film or foil and the like to sandwich said particulate material clusters 703, preferably comprising large amounts of absorbent polymer material, between the carrier layer 401 and auxiliary layer 501. Alternatively the auxiliary layer 501 can also represent a homogenous and/or heterogeneous layer of glue, adhesive, binders, resins, thermoplastic material and the like, capable of sandwiching the particulate materials clusters 703 between the carrier layer and auxiliary layer. This relative expensive, technically challenging and environmentally burdensome alternative embodiment according to the invention is however not preferred above the typical non-woven, paper or tissue like layer for instance.
The clustering means 250 is suitably constructed and arranged to direct a selected flow of particulate material 201 onto the carrier deposit zones 415 of the carrier layer 401. It should be appreciated that other particulate material 201 may also be introduced via the clustering means 250 as desired. A particulate supplying means 200, such as for instance a K-Tron weight and loss feeder, Model No K10s, type of particulate delivery system can be configured to deliver required amounts of particulate material 201 through a feeding tube 205 into the clustering means 250. The particulate material 201 reach the perforations 304 by means of gravity and/or other physical forces. In particular embodiments, a conventional air-conveying system may be employed to move and guide the particulate material 201 and resultant particulate material stream to the desired locations in the clustering means 250. Alternatively such forces may e.g. be electro-mechanical forces in case the particulate material 201 is responsive to a magnetic field and magnets are placed to guide the particles towards the perforations 304. Alternatively, the particulate material 201 can, for instance, be gravimetric or volumetric assessed, guided and fed indirectly via the feeding tube 205 and/or directly into the clustering means 250 under the influence of gravity without the use of additional conveying air.
Optionally, one can also provide a vacuum suction system in function of the deposit zones 415 of the carrier layer 401, creating an air flow towards the perforations 304 and/or deposit zones 415. Such vacuum suction system would generate suitable levels of vacuum within an appointed vacuum section, and would provide a desired level of vacuum within the clustering means 250. It should be readily appreciated that such particular levels of vacuum generated within clustering means 250 and/or drum 100 would depend upon the individual circumstances of the manufacturing line. For example, at higher rates of rotation of the drum 100, relatively higher levels of vacuum may be required within clustering means 250. In addition, the use of conveying means to transport the particulate material 201 into the clustering means 250 may necessitate the use of even higher levels of vacuum. It should also be readily appreciated that the levels of vacuum shall also depend upon the porosity of the carrier layer 401, and the usage of possible carrier layer 401 would for instance be limited to fibrous web materials and/or perforated films and foils. For the reason above and in light high energy consumption this vacuum suction usage is an alternative embodiment according to the invention, however not one of the most preferred one. These vacuum means, acting as positioning means, can be used to stabilize, position and/or reposition the printed particulate materials to their final pocket position before being pocketed. The printing pattern and pocketing position preferably can but do not have to coincide with one another, as it may be desirable to print on for instance limited surface areas while just prior to pocketing spreading the materials to the total available unbounded regions so as to allow maximum distribution of the individual clustered particulate material over the available surface area upon pocketing, not being limited by any technical specifications of the clustering means since they are overcome by the positioning means.
More economically and environmentally beneficial production processes with lower energy usage and more freedom on the choice of carrier layer 401 are preferred. Further to extensive testing it was demonstrated that using gravity will be sufficient for a wide range of particulate material 201 usages at various production speeds.
The particulate material 201 supplied via the particulate material supplying means 200 is preferably provided in uniform particulate material stream, reaching a width equal to or slightly greater than the width 310 of the perforation pattern 300 on the side of the inlet regions 304a. In order to improve uniformity, a vibrating supply means 200 might be used. In a preferred embodiment, a feeding tube 205, with a proximal opening 206 and distal opening 207 can be used to concentrate the particle material stream onto a certain area. Such feeding tube 205 may have various suitable longitudinal and transversal shapes and is preferably designed in light of the dimension and shape of the clustering means 250, its perforation pattern 300, its perforations 304 and the desired printing pattern 320. The feeding tube 205 may also converge towards the clustering means 250 to effectively and efficiently guide the particulate material stream to the inlet regions 304a. The particle supply means 200 preferably contains a continuous supply and a dosing system 204 of a gravimetric, volumetric or other type so as to control the quantity and quality of particles fed into the perforations 304. Such particle supply means are being offered and supplied by Acrison, Inc., with offices in New Jersey, New York.
The particle material 201 such as absorbent polymer material, more preferably absorbent particulate polymer material may be provided and used in various shapes or forms, such as granular, spherical, flakes, fibrous, and will often consist of irregularly shaped particles, having a mean particle size from about 10 μm to 1000 μm, preferably with less than about 5% by weight having a particle size of 5 μm, and preferably with less than about 5% by weight having a particle size of more than about 1200 μm. For use in absorbent structures to be used in absorbent articles, an absorbent material will be selected which can swell upon contact with liquids, such as bodily exudates. Such materials can be supplied in a granular form by Evonik from Essen, Germany, BASF from Antwerp, Belgium, Nippon Shokubai from Osaka, Japan and San-Dia from Tokyo, Japan. These are cross-linked polymeric materials that can absorb at least about 5 times their weight of an aqueous 0.9% saline solution as measured using the Centrifuge Retention Capacity test (Edana 441.2-01).
The web supplying means 400 can include a conventional spindle and supply roll controlling mechanism of the type that is known in the art. For example, suitable mechanisms are available from Martin Automatic Inc., a company having offices in Rockford, Ill.
The carrier layer 401 may preferably be brought in their desired position via guiding systems 402 and the auxiliary layer 501 may preferably be brought in their desired position via the guiding systems 502, and the support means 600 is preferably controllably strained via tensioning means 603 and operated via guiding means 601 and 602. The composite material 700 is preferably guided via guiding means 603 and the desired material 702 is preferably guided by guiding means 604.
The carrier layer 401 can be any suitable material web which has sufficient strength to process through the apparatus, and preferably economically, environmentally and usage sensible. The carrier layer 401 may comprise a paper or fibrous tissue, woven or non-woven fabric, a cellulose web or batt, airlaid or wet laid structure or the like. Alternatively, the carrier layer 401 is a porous, gas permeable web material such as a porous film or fibrous web.
The auxiliary layer 501 can be any suitable material web which has sufficient strength to process through the apparatus, and preferably economically, environmentally and usage sensible. The carrier layer 401 may comprise a paper or fibrous tissue, woven or non-woven fabric, a cellulose web or batt, airlaid or wet laid structure or the like. Alternatively, the carrier layer 401 is a porous, gas permeable web material such as a porous film or fibrous web. Furthermore the auxiliary layer 501 can also represent for instance a spray, film and/or layer of glue, adhesive, binders, resins, thermoplastic material and the like together with the carrier layer 401 capable of sandwiching the particulate material clusters 703.
The carrier layer 401 and/or auxiliary layer 501 may also be an essentially endless web material in the longitudinal direction. One preferred web material is a so called SMS material, comprising a spunbonded, a melt-blown and a further spunbonded layer. Highly preferred are permanently hydrophilic non-wovens, and in particular nonwovens with durably hydrophilic coatings. An alternative preferred material comprises a SMMS-structure. Another preferred web material is a nonwoven containing cellulosic fibers, paper or tissue sheet or other airlaid, drylaid or wetlaid material, as these products greatly improve the wicking capacity of the product. The web materials 401 and 501 may be provided from two or more separate sheets of materials or they may be alternatively provided from a unitary sheet of material. Preferred non-woven materials are provided from synthetic fibers, such as PE, PET and most preferably PP. As the polymers used for non-woven production are inherently hydrophobic, they are preferably coated with hydrophilic coatings.
The clustering means 250 can preferably be mounted onto a or unitary with a drum 100 having perforations 304 arranged in a perforation pattern 300 along its circumferential- and/or width-wise direction and thus directly or indirectly piercing or perforating the drum 100 in the radial direction, from its inner surface 101 to its outer surface 102. Alternatively, according to another embodiment of the invention, the clustering means 250 are replaceably mounted and/or unitary incorporated on a substantially endless belt carried on a system of transporting rollers. Suitable forming belt systems are available from Paper Converting Machine Company, a business having offices located in Green Bay, Wis. Driving means, such as conventional electric motors or the like, are constructed and arranged to rotate or otherwise move and translate the clustering means 250 at a predetermined surface speed along a desired manufacturing direction and speed. The various configurations of the invention can advantageously provide the desired composite structures while operating at high surface speeds of at least about 0.5 m/sec, preferably at least about 1 m/sec, more preferably at least about 3 m/sec and most preferably more than 7 m/sec.
The carrier layer 401 is delivered onto or adjacent the outer peripheral surface of the clustering means 250 mounted onto or unitary with drum 100. As the drum 100 rotates, the moving surface of the drum 100 transports the clustering means 250 and the support means 600 guides the carrier material 401 in close proximity and past the clustering means 250 in light of the intended deposit of particulate material clusters onto the deposit surface 415 of the carrier layer 401. For the sake of simplicity, the wording ‘drum’ is used, denominating an essentially round circumference, but it is clear to the person skilled in the art that any type of endless body, provided with the desired perforation pattern 300 can be used. The surface of such body can be rigid such as in perforated aluminium plates, or soft such as in a belt. Preferably, a drum 100 made out of steel frame with reinforced aluminium plates will be used.
With reference to
The perforations 304 can have a variety of shapes including, but not limited to, circular, oval, square, rectangular, triangular, and the like. The perforation pattern 300 shown in
With reference to
With reference to
If the perforations 304 are overfilled, i.e. if more particulate material 201 is present than the perforations 304 can take or than can instantaneously be evacuated via the perforations 304, one has ‘overfill’. Particulate material 201 will then accumulate and rise until above the level of the top opening 302 of the perforation 304. In that case, a sweeping means 208 will level the surface of the particulate material 201 with that of the inner surface 101 of the drum 100 and thus remove the excess particulate material 201 so that only a volume of particulate material 201 essentially corresponding to the volume of the perforation 304 is being transferred to the carrier material 401 during depositing. The sweeping means 208 can be for instance a scraper bar made out of durable material, or, as depicted in
As explained above, the overfilling method functions with sweeping means can act as a volumetric dosing system, where the prescribed volumes, dimensions and shapes of the perforations 304 act as the volumetric dosing and printing space and gives excellent results if the particulate material 201 is very homogeneous in density and particle size, or if the weight of the dosed particles is less relevant than their volume.
However, in many cases it is required to dose the correct weight, rather than the corresponding volume. Such particulate material 201 often have irregular densities by nature and/or such irregular densities are often aggravated by handling and transportation whose vibrations cause the particulate material 201 to segregate, bringing the lower density particles on top and the higher density particles below. Using a volumetric method could then result in important weight differences from one product to another which is undesirable, making gravimetric dosing preferably.
Carrier layer 401 which is delivered by the web supplying means 400 onto the support means 600 delivers the carrier layer 401 in close proximity of and preferably against the outer periphery of the clustering means 250. If the clustering means 250 and the carrier material 401 are pressed to one another they tightly seal off the outlet regions 304b and when preferably moving at essentially zero speed difference to one another, the particulate materials 201 fed by the supply means 200, preferably guided via feeding tube 250, are able to be continuously and controllably deposited onto the clustering means 250 into the perforation 304 via the inlet regions 304a thereby creating the particulate material printing pattern 320 on the deposit zones 415 of the carrier layer 401. Preferably an additional positioning step is provided via a clustering means in the form of for instance a vacuum means and a combination of elevations and/or recessions to further stabilize, position and/or reposition the printed particulate material clusters. Optionally, the particulate material clusters 703 are immobilised, bond, joined and/or otherwise secured restrained in relation to the carrier layer via any suitable means, such as for instance glue, binder, sprays, films, network, webs, etc.
Due to the gravity or other forces, the particulate material 201 will exit the perforations 304 via their bottom opening 301, thereby providing the desired printing pattern 320. This desired printing pattern 320 is substantially retained when the drum 100 separates from the carrier material 401. In the absence of a relative close seal in between the outer surface of the clustering means 250 and the deposit surface 411 of the carrier material 401, a gap 103 will create a possible blurring effect of the desired printing pattern 320, since the drum 100 and carrier layer 401 move at significant speeds and allow migration of the particulate materials 201. Therefore it is recommended to keep the gap 103 a small as technically acceptable.
However, even with a very small gap 103, it is obvious to the person skilled in the art that, depending on the nature of the particulate material 201 and on the amount of particulate material 201 one wants to deposit via one single perforation 304, the actual resulting printing pattern 320 might differ slightly from the perforations pattern 300. The effect is caused by gravity which might pull the particulate material clusters 703 apart so that the particulate material footprint 705 on the carrier layer 401 is wider and/or larger than the bottom opening 301 of the perforations 304 and the forces of inertia might further distort the printing pattern 320 in the direction of the web movement, thereby creating a skewed image 704. Preferably here additional positioning steps are provided via a positioning means.
The composite structure 700 as a combination of the auxiliary layer 401 and the particulate material clusters 703 is moved away from said clustering means 250 via a transport means, while in case required a positioning means ensures the particulate material clusters 703 are not unacceptably distorted, the particulate materials 201 do not unintentionally migrate to the inter-deposit zones 416 and/or are lost or wasted due for instance high machine speeds, air and material flows, gravitational and other forces and the like. In a preferred embodiment the composite structure 700 is immediately stabilised when taken over from the carrier material support means 600 by for instance opposing contact pressured longitudinal conveyer belts, vacuum suction means, or the like. Transport means can be unitary with positioning means.
As a next step, one does immediately bond or join a second web material such as for instance an auxiliary layer 501 directly or indirectly unto the carrier layer 401 and the particulate material clusters 703 deposited thereon according to printing pattern 320, and the resulting sandwich structure is additionally preferably secured via an ultrasonic attachment means 800 so that the particulate materials 201 are sandwiched, immobilized, bonded, joined and/or restrained in between the carrier layer 401 and auxiliary layer 501 in their desired location and shapes by means of the thereby formed pockets or compartments.
Alternatively the auxiliary layer 501 can for instance also comprise a liquid-permeable layer or web material, such as films, foils, tissues, fabrics, webs or the like. The layer may for instance comprise paper, tissue, wet laids or drylaids, wovens or non-woven and/or may be composed of for instance hydrophilic materials or composed of a hydrophobic material which has been suitably treated to render it sufficiently hydrophilic.
Additionally the composite structure 700 and/or absorbent structure can be alternatively and/or complementary be further combined with any and all other suitable covering, absorbency feature enhancing, protective, functional, structural and/or strengthening materials, fabrics and/or webs (e.g. acquisition layer, surge layer, distribution layer, wicking layer, backing layer, elastic layer, colored layer, perfumed layer, lotion layer, informative layer, etc) and the like.
Auxiliary layer 501 can preferably be bound or joined to the carrier layer 401 with the particulate material clusters 703 immobilized and/or restrained there between via attachment means 800 such as for instance ultrasonic and/or other thermal, mechanical or thermo-mechanical bonding techniques. Such discrete bonds or joints in between the carrier layer 401, particulate material clusters 703 and/or auxiliary layer 501 can preferably be provided in one or more of the inter-deposit zones 416 in the form of grids, patterns, lines, dots and the like.
In a particular aspect of the invention, the ultrasonic attachment means 800 can be configured to creating substantially permanent primary attachments and substantially detachable secondary attachments leading to a substantially water-sensitive absorbent structure. The resultant attachment means provides an attachment system wherein the strength of the attachment means is great enough to adequately hold the carrier layer 401 and the auxiliary layer 501 together when the system is substantially dry and also when the absorbent structure is partially or fully wetted. In addition, the strength of the attachment system is configured to be sufficiently low so as to not excessively constrict the swelling expansion of absorbent particulate polymer materials during the absorption of liquid. The strength of the attachment means is preferably less than the separating force imparted by the swelling of the high absorbency material when the absorbent particulate polymer material is exposed to liquids. In addition, the attachment system is preferably configured to release at an applied load which is less than the load needed to delaminate the attachment means without excessively tearing the material forming either or both of the carrier layers 401 and/or auxiliary layer 501 when such layers are wetted. The attachment system is preferably also configured to release at an applied load which is less than the load needed to excessively burst the material forming either or both of the outer layers of the absorbent structure when wetted. Typically, the applied load is a generally tensile load resulting from the pressure exerted by the expanding absorbent particulate polymer material when the particulate material absorbs liquid and swells. The appropriate attachment means are constructed and arranged to be sufficiently strong to withstand this pressure and substantially avoid bursting or tearing. Such ultrasonic bonding system can for instance be supplied by Herrmann, from Germany.
The attachment means for securing together carrier layer 401 and auxiliary layer 501 may also be constructed to provide any other suitable connecting mechanism, such as thermal bonds, sonic bonds, stapling, stitching, or the like. The attachment means 800 can preferably be configured to provide operable pockets particulate material clusters 703 between the carrier layer 401 and auxiliary layer 501. Optionally, a perimeter means can be included in the process to obtain a mechanism for providing substantially continuous side attachment regions, and a selected pattern of intermittent, longitudinally-spaced, medial attachment regions. The perimeter attaching means may be configured to provide other types of securing, such as sonic bonds, thermal bonds, stitching, sewing, or the like.
The auxiliary layer 501 can preferably be provided by covering means 500 and a guiding system 502 of transporting rollers and conveyers which are configured to deliver the auxiliary layer into a contacting relation with the composite structure 700 comprising a carrier layer 401 and the printing pattern 320 of particulate material clusters 703.
With reference to
Creating constantly and quickly repeating pulses of particulate material 201 suspended in a conveyer means 225 such as air has been a long lasting desire for many applications, in particular for pulses which are well controlled both with regard to their shape, their frequency and the amount of material transferred during these pulses. A particular useful application is during the manufacture of disposable absorbent articles, such as feminine hygiene garments, baby diapers, baby pants and/or adult incontinence garments and the like, where the manufacturing aims at high production speed and low variability. This can be achieved by means of the deflector 220 which will interrupt the particle material stream by pushing the particulate material 201 into a recovery tube 215 and can thus create pulses of particulate material 201. The advantage is that one can thus choose not to print certain segments of the drum 100, i.e. leave certain areas of the perforation pattern 300 void of particle material. Also, the unprinted segments of the drum 100 can vary from one rotation of the drum to another, thereby saving enormously on the investment cost of providing different drums 100 with different perforation pattern 300, and on the maintenance and production cost of changing such different drums 100. As an example: with this solution, it is possible to manufacture composite structure 700 or absorbent structure for the use in absorbent articles such as diapers in all sizes, from the smallest one to fit a newborn baby unto the bigger ones for toddlers, on just one drum 100, which is not possible with conventional techniques known in the art and is highly appreciated and advantages.
The absorbent article is shown in its flat out, un-contracted state with the wearer side facing the viewer. Portions of the absorbent article are cut away to more clearly show the underlying structure of the diaper 10 including the absorbent elements and absorbent components. The chassis 12 of the diaper 10 in
The back sheet 20 covers the absorbent structure 14 and preferably extends beyond the absorbent structure 14 toward the longitudinal edges 42 and end edges 44 of the diaper 10 and may be joined with the top sheet 18. The back sheet 20 prevents the bodily exudates absorbed by the absorbent structure 14 and contained within the diaper 10 from soiling other external articles that may contact the wearer, such as bed sheets and undergarments. In preferred embodiments, the back sheet 20 is substantially impervious to bodily exudates and comprises a laminate of a non-woven and a thin plastic film such as a thermoplastic film. The back sheet 20 may comprise breathable materials that permit vapour to escape from the diaper 10 while still preventing bodily exudates from passing through the back sheet 20. It may be semi-rigid, non-elastic and can be made fully or partially elasticized and include backing. The back sheets 20 may be assembled in a variety of well-known configurations and are well known in the art.
The diaper 10 comprises a top sheet 18 that is preferably soft, compliant, exhibits good strikethroughs and has a reduced tendency to rewet from the liquid absorbent material. The top sheet 18 is placed in close proximity to the skin of the wearer when the diaper 10 is worn. In this way, such top sheet 18 permits bodily exudates to rapidly penetrate it so as to flow toward the absorbent structure 14 more quickly, but preferably not allowing such bodily exudates to flow back through the top sheet 18. The top sheet 18 may be constructed from any one of a wide range of liquid and vapour permeable, preferably hydrophilic, materials. The upper and lower surface of the top sheet 18 may be treated differently and may for instance include a surfactant on the upper surface so as to facilitate liquid transfer there through, especially at a central zone or area of the top sheet 18 located over the absorbent structure 10, and for instance include a hydrophobic agent on the lower surface to minimize the liquid contained within the absorbent core from contact wetting the top sheet 18 thereby reducing rewet values. The top sheet 18 may also be coated with a substance having rash preventing or rash reducing properties (e.g. aloe vera). The top sheet 18 covers substantially the entire wearer facing area of the diaper 10, including substantially all of the front waist region 30, back waist region 32, and crotch region 34. Further, the side panels 22 and/or waist feature layers of the inner region may be formed from the same single top sheet material and, thus, may be referred to as being unitary with the top sheet 18 in forming longitudinal and lateral extensions of the top sheet 18 material. Alternatively, the top sheet 18 may be formed from multiple different materials which vary across the width of the top sheet 18. Such a multiple piece design allows for creation of preferred properties and different zones of the top sheet 18. The top sheet 18 be semi-rigid, non-elastic and can be made fully or partially elasticized. The top sheet 18 may be assembled in a variety of well-known configurations and are well known in the art.
The absorbent structure 14 in
The diaper 10 may also utilize a pair of containment walls or cuffs 24. Each cuff 24 is a longitudinally extending wall structure preferably positioned on each side of the absorbent structure 14 and spaced laterally from the longitudinal axis 36. The longitudinal ends of the cuffs 24 may be attached or joined, for example, to the top sheet 18 in the front and rear waist regions 30 and 32. Preferably, the ends of the cuffs 24 are tacked down inwardly and attached, for example, by adhesive or sonic bonding to the lower structure. Such a construction effectively biases the cuffs 24 inwardly and is generally considered to cause the cuffs 24 to exhibit improved leakage prevention properties. Preferably, the cuffs 24 are equipped with elastic members 28, which extend along a substantial length of the cuffs 24. In a common application, the elastic members 28 are placed within the cuffs 24, preferably at the top of the cuff 24 while in a stretched condition and then glued or sonic bonded to the cuff 24 at least at their ends. When released or otherwise allowed relaxing, the elastic members 28 retract inwardly. When the diaper 10 is worn, the elastic members 28 function to contract the cuffs 24 about the buttocks and the thighs of the wearer in a manner, which forms a seals between the diaper 10, the buttocks and the thighs. The cuffs 24 may be assembled in a variety of well-known configurations and are well known in the art.
The diaper 10 may also employ additional layers known in the art including an acquisition layer or surge layer, preferably situated between the top sheet and the absorbent core and highloft and/or coverstock layers. This serves to slow down the flow so that the liquid has adequate time to be absorbed by the absorbent core.
In order to keep the diaper 10 in place about the wearer, preferably at least a portion of the back waist region 32 is attached by fastening or securing members 46 to at least a portion of the front waist region 30, preferably to form leg openings and an absorbent article waist. Fastening or securing members 46 carry the tensile load around the absorbent article waist and compliment the elastic members 28 by providing a quasi-seal between the wearer, the elastic waist feature 26 and cuffs 24, so that bodily exudates are contained within the diaper 10 which are then absorbed. In other words, so that it does not leak through gaps between the wearer and the edge of the diaper 10. The fastening or securing members 46 may for instance be adhesive, mechanical fasteners, hook and loop features, conceivable strings and/or combinations thereof, i.e., anything that will secure one end of the diaper 10 to the longitudinally opposite end of the diaper 10. The fastening or securing members 46 may also be co-adhesive such that they adhere to each other but not other materials. The fastening or securing members 46 and any component thereof may include any material suitable for such a use, including but not limited to plastics, films, foams, non-woven webs, woven webs, paper, laminates, fibre reinforced plastics and the like, or combinations thereof. It may be preferable that the materials making up the fastening or securing members 46 are flexible, extensible and/or elastic, allowing them to better conform to the shape and movements of the body and thus, reduces the likelihood that the fastening system will irritate or injure the wearer's skin. Preferably, the diaper 10 is affixed to the wearer by tape fasteners which are permanently affixed to the back sheet 20. Tape fasteners are contacted with the transversely opposite side panel or ears 22 attached or joined and extending from the back sheet 20, where they remain affixed due to the binding compound applied to the fasteners. Alternatively, the absorbent article may be pants and the like. In this configuration, the absorbent article may or may not have tape fasteners. Specific disposability tapes may however also be provided on such absorbent articles. All fastening and securing elements 46 may be assembled in a variety of well-known configurations and are well known in the art.
The waist regions 30 and 32 each comprise a central region and a pair of side panels or ears 22 which typically comprise the outer lateral portions of the waist regions. These side panels 22 may be unitary with the chassis 12 and/or back sheet 20 or may be attached or joined thereto by any means know in the art. In a preferred embodiment of the present invention, the side panels 22 positioned in the back waist region 32 are flexible, extensible and/or elastic in at least the lateral direction (i.e., elasticized side panels), in another embodiment the side panels 22 are non-elastic, semi-rigid, rigid and/or stiff. This variety of side panels 22 are well known.
Furthermore waistbands 26 employing elastic members can be positioned along the transverse portion of the diaper 10 so that when worn, the waistbands 26 are positioned along the waist of the wearer. Generally, the waistband 26 preferably creates a seal against the waist so that bodily exudates do not leak from the regions between the elastic waistband 26 and the waist of the wearer. Although the bodily exudates are primarily absorbed by the absorbent materials within the diaper 10, the seal is important considering the assault of liquid by the wearer may overwhelm the absorption rate capacity of the absorbent structure 14. Hence, the waistbands 26 contain the liquid while it is being absorbed, they are well known in the art. The absorbent article such as a diaper 10 may also include such other features, components and elements as are known in the art including front and rear ear panels, waist cap features, elastics and the like to provide better fit, containment and aesthetic characteristics. These features may be assembled in a variety of well-known configurations and are well known in the art.
| Number | Date | Country | Kind |
|---|---|---|---|
| EP10447025.7 | Oct 2010 | EP | regional |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2011/005286 | 10/20/2011 | WO | 00 | 8/12/2013 |
