GB2539668A - Method for applying particles to a moving web and apparatus therefor - Google Patents

Abstract

The process comprises the steps of: having a web supply and transport system ; a particle 1010 supply system; a particle lay down system and a particle delivery system 1100. The lay down unit includes two zones by a separation of at least non zero amount C. The delivery system includes a divider unit 1500 including housing with an inlet, at least two outlets 3700, 3800 and a diverter 1600. Inlet piping delivers a particle stream from the supply to the divider unit. The outlets are connected to piping which deliver the particles to respective said zones. An feed of particles is supplied to the divider unit. The web supply moves at a speed through the lay down unit. The diverter is operated such that at a first time interval a percentage of the particle stream is directed to a first outlet piping and for a second time interval the feed is supplied to the first outlet and the remaining percentage of time the feed is sent to a second outlet piping. The web speed, separation and times can be adjusted so that the particle loaded web includes a repeating pattern varied by amount or weight. The diverter may be a hinged flap 1600, rotatably mounted diverter nozzle or a rotating diverter disc including an opening.

Description

Intellectual Property Office Application No. GII1511008.3 RTM Date *19 January 2016 The following terms are registered trade marks and should be read as such wherever they occur in this document: Fritsch (page 16) Intellectual Property Office is an operating name of the Patent Office www.gov.uk/ipo

METHOD FOR APPLYING PARTICLES TO

A MOVING WEB AND APPARATUS THEREFOR

Field of the invention

The present invention relates to a method of and an equipment for a particular application of particles to a moving web. Among various uses such as in the food industry for the making of confectionary or baked articles like pizzas, addition of particulate additives such as super absorbent material to a fibrous web is of interest in the hygiene industry for the manufacturing of absorbent structures in absorbent articles such as diapers, feminine hygiene or adult incontinence articles

Background

Applying particles discontinuously to moving surface is often used in a variety of applications. For example in food processing industry, powders or granules are applied to a continuous web, such as dough, or to precursor articles on a continuously moving web, such as pizza dough shells on a baking belt.

There is further a wide field of applying particles to web materials in the hygiene industry. For absorbent articles, such as baby diapers, feminine hygiene products, adult incontinence articles and the like, particulate material is often added to a web, such as a fibrous web that may he pre-formed or that may be formed in-line in a previous process step.

In particular with the use of superabsorbent particles profiling or intermittent application thereof became customary in the context of mixtures with fibres, such as cellulosic fibres, and the higher the concentrations of the SAP in the mixture, the more important profiling and intermittent application became.

A further step in the development of absorbent articles led to absorbent structures that were essentially free of cellulose, and the superabsorbent material was positioned on and/or in fibre interstices of fibrous webs and/or enveloped in fibrous webs such as nonwoven webs.

In EP1621165, a method is described wherein SAP is "printed" by filling cavities in a first drum and subsequently expelling these particles into indentations of a web material whilst adhesive is applied thereto. The indentations are created by supporting the web at predetermined support regions, that remain essentially free of particles. Upon application -2 -of a further web, a sandwich structure is created, wherein particles are bonded to each other and the webs are connected to each other in particular in the particle free regions. Such a structure may be applied as liquid storage core in an absorbent article.

Similarly, in W02101/048878, particles are "printed" onto a nonwoven web in a particular pattern aiming at creating particle free zones between particle heaps, that allow subsequently ultrasonic bonding in these particle free zones.

In DE19530771, a system is described with an essentially continuous belt with indentations. These indentations are filled with SAP particles in a hopper, which are then transferred to a moving web.

However, such "printing" systems are quite complicated in design and represent significant effort and cost. Also, when applying air permeable carrier structures, these may be prone to screen blinding that may result in unreliable operation and or increased maintenance effort.

However, all such "printing" systems carry at least the disadvantage of not being flexible with regard to design of format changes, of risking particles in zones which are supposed to be particle free, and of instable process conditions.

In US8727 I 82, a system is described which allows an intermittent flow of particles from a hopper by using a base with an opening, whereby the base is rotatably mounted relative to the hopper, thereby closing and opening the hopper opening.

In W02003/101622, a system is described, where an essentially continuous flow of SAP particles is interrupted by a valve-type arrangement, wherein a disc may rotate around an axis which is essentially perpendicular to the direction of the particle flow and thus interrupt the particle flow It is also known to remove particles from a particle stream by applying a pulsed air stream perpendicular to the flow direction of a particle stream, as described in JP2004/000830, or by sucking the particles away, as described in JP63-283777.

In U55213817 (McNeill PPC), a system is described wherein a continuous stream of particles is fed from a nozzle, which moves between a first position, in which the particles are directed towards a moving web, and a second position, in which the particles are directed to a recycle system.

US5156902 describes an apparatus for forming a zoned distribution of particulate material within a fibrous web, which includes a conveying mechanism for providing a gas entrained supply of the particulate material and a segregating mechanism for centrifugally directing at least a portion of the particulate material into an accumulation region of the apparatus. A transferring mechanism selectively directs particulate material from the -3 -accumulation region into a delivery gas stream to provide an intermittent flow volume of a selected quantity of particulate material from the accumulation region through a delivery conduit and into a web forming chamber. A fiberizing mechanism provides a flow of a selected fibrous material into the web forming chamber, and a directing mechanism controls the intermittent flow of particulate material from the delivery conduit into the forming chamber. A foraminous forming layer is disposed within the forming chamber for receiving the fibrous material and the particulate material to produce a fibrous web which includes zoned regions having selected, different amounts of the particulate material therein.

However, such particle flow interruption systems tend to introduce undesired fluctuations of the airstream carrying the particles and hence unstable process conditions.

Henceforth there is still a need for a process and an equipment for creating a pattern / profile of particles when laid onto a flat, moving surface.

Summary

In one aspect, the present invention is a process for applying particulate material to a moving web to form a particle loaded web. The process comprises the steps of -providing a web supply and transport system; a particle supply system; a particle lay-down unit, comprising a first and a second particle lay-down zone that are machine directionally offset at a separation zone length C greater than zero; a particle delivery system comprising a divider unit, comprising a housing, comprising an inlet, and at least a first and a second outlet, a diverter; inlet piping for delivering a particle stream from the particle supply to the divider unit; at least a first and a second outlet piping connected to the at least first and second outlet for delivering particles from the divider unit to the particle lay down unit, wherein the first outlet piping is designed to deliver particles to the first particle lay- -4 -down zone, and the second outlet piping is designed to deliver particles to the second particle lay-down zone; - feeding an infeed stream of particles from the particle supply of the particles to the -divider unit; - feeding the web at a web speed through the particle lay down unit; characterized in that it further comprises the steps of -operating the diverter of the divider unit such that for a first time interval a first percentage of the infeed particle stream is directed into a first outlet piping forming a first outlet particle stream and for a second time interval a second percentage of the infeed stream different to the first percentage is directed into the first outlet piping, whilst the respective remainder of the infeed particle stream is directed to the second outlet piping forming a second outlet particle stream; - feeding the first and the second outlet particle streams through the first or the second outlet piping, respectively, to the first or the second particle lay-down zone; - adjusting (i) the particle residence time of the particles in the first outlet piping and in the second outlet piping, and (ii) the zone separation length C. and (iii) the web speed, such that the particle loaded web comprises a repeating pattern of at least a first and a second region differing in amount / basis weight of particles applied thereto.

The process may further comprise the steps of - providing a further lay-down zone; a further outlet of the divider unit; a further piping connecting the further outlet with the further lay-down zone designed to deliver particles to the further lay-down zone; -operating the diverter such that for a first time interval a first percentage of the infeed particle stream is directed into a first outlet piping forming a first outlet particle stream and -5 -for a second time interval a second percentage of the infeed stream different to the first percentage is directed into the first outlet piping, whilst the respective remainder of the infeed particle stream is directed to the second outlet piping or to the further outlet piping forming a second and a further outlet particle stream.

Optionally, one of the first or second or further regions may be essentially free of particles.

The process may further comprise the step of separating the web into web pieces, each comprising the repeating pattern of at least a first and a second region.

The diverted may be operated such that an outlet is fully closed whilst at least the second or a further outlet is fully open.

The diverter may be executed in several variants: In a first one, the diverter comprises a hinged diverter flap positioned between a first and a second outlet, and the operating of the diverter comprises the step of moving the hinged diverter flap from a first position to a second position at a higher speed than when moving it from a second position to a first position.

In a second one, the diverter comprises a rotatably mounted diverter nozzle, and the operating of the diverter comprises the step of rotating the rotatably mounted diverter nozzle around an axis essentially aligned to the direction of the infeed stream.

In a third one, the diverter comprises a rotatably mounted diverter tool and the operating of the diverter tool comprises the step of rotating the diverter tool at an angle relative to the rotating axis, such that its outlet diverts particles to the first or to the second or to the further outlet piping.

In yet a fourth one, the diverter comprises a rotatably mounted diverter disk comprising at least one diverter disk opening, and the operating of the diverter comprises the step of rotating the diverter disk such that the infeed particle stream is diverted through the di verter disk opening to the first or to the second or to the further outlet piping.

The process may further comprise the step of providing a particle carrier medium, preferably air, to one or more of the inlet, first, second and further outlet piping for adjusting the particle residence time of the particles in the inlet, first, second or further outlet piping.

In a second aspect, the present invention relates to a method for the manufacturing of a series of web pieces comprising the steps of -providing a particle loaded web according to any of the preceding claims;

-

separating the particle loaded web into a series of web pieces, such that each of the web pieces comprises predetermined first and second regions. Such a method may be particularly suitable for the manufacture of a series of web pieces in a manufacturing process for forming absorbent articles.

In a third aspect, the present invention is a system for applying particulate material to a moving web to form a particle loaded web, which comprises - a web supply and transport system; - a particle supply system; a particle lay-down unit, comprising a first and a second, optionally a further particle lay-down zone that are machine directionally offset at a separation zone length C greater than zero; a particle delivery system comprising a divider unit, comprising a housing, comprising an inlet, and at least a first and a second and optionally a further outlet, a diverter, preferably selected from the group consisting of a hinged diverter flap; a rotatably mounted diverter nozzle; a rotatably mounted diverter disk comprising at least one diverter disk opening, inlet piping for delivering a particle stream from the particle supply to the divider unit; at least a first and a second outlet piping connected to the at least first and second outlet for delivering particles from the divider unit to the particle lay down unit, wherein the first outlet piping is designed to deliver particles to the first particle lay-down zone, and the second outlet piping is designed to deliver particles to the second particle lay-down zone; wherein the first outlet piping is adapted to deliver particles to the first particle lay-down zone, and the second or further outlet piping is adapted to deliver particles to the second or further particle lay-down zone, respectively, and wherein first and the second or further particle lay-down zones are machine -7 -directionally offset at a separation zone length greater than zero.

At least one of the outlet piping is optionally flexibly adjustable in its length and/or machine directional positioning.

Brief description of the Figures

Fig. 1 shows schematically the general set-up of an equipment according to the present invention for executing a process according to the present invention.

Fig. 2A and B depict schematically time intervals in the process according to the present invention.

Fig. 2C depicts schematically a particle distribution profile according to the present invention in a web piece or an article.

Fig. 3 A and B shows schematically an execution of an equipment suitable for the present invention at two different process steps.

Fig. 4 A, B, and C show schematically a further execution of an equipment suitable for the present invention at two different process steps.

Same numerals in various figures depict same or equivalent elements.

Detailed description

The term "web material" refers to a material, which is essentially endless 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. Typically, the web materials will have a thickness dimension (i.e. the z-direction) which is significantly smaller than the longitudinal extension (i.e. iii 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 a web material may be a plastic films or foils, textiles, non-wovens, nets, scrims, paper, or cartons, or combinations thereof. 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 he 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.

Webs may be of essentially uniform composition, they can be mixtures of materials, they can be composites of materials such as being layered (different materials arranged in a juxtaposed position in the z-direction) and/or can comprise stripes of different materials or materials having different or varying properties (i.e. arranged in a juxtaposed position in the y-direction).

The selection of the material for forming webs is not particularly limited and depending on the specific application.

For particular executions webs may be air-permeable. Often webs exhibit certain wettability properties, such as being hydrophobic or hydrophilic. Webs may also be essentially impermeable to fluids, such as to aqueous liquids, etc..

For various applications, a suitable web material is a nonwoven material, such as a carded, wet-or airlaid web, or a melts-spun web, which may be a single layer or which may comprise several layers of melt-spun, spunboncied, and / or melt-blown webs, and may be denoted as "SMS", "STVIMS", SSMTVIS, webs, wherein "S" stands for spunbonding and "MT for melt-blowing.

Basis weights can be relatively low, such as being as low as a few g/m2 for example 5 g/m2, though they will typically he more than 10 g/m2. Relatively high basis weights can be over 100 g/m2, such as 300 or even 500 g/m2 or more.

The term "web" as used herein also includes a sequence of web material pieces or other pieces a may be positioned to run through the system according to the present invention, on a support means, such as a transport belt, for example, when pieces of flat dough are placed on a belt and various additives are placed on the dough at predetermined positions on the dough pieces, such as may be suitably applied in the manufacturing of pizzas.

The selection of particles useful for the present invention is not particularly limited, and may be bulk particulates, such as granules, powders, flakes and the like. Preferably the particles are free flowing, i.e. particles may move independently from other particles under external forces, such as gravity or forces exerted by a carrier medium, such as air. Particles may be aggregates of smaller sub-particles, which may be strongly associated, such as upon sintering or by inter-particle chemical reactions, or only weakly associated such as by hydrogen bonding. Preferably, though not necessarily, the bulk particles do not change properties significantly by the process according to the present invention.

Particle sizes will often be between 50pm and about 2000 pm, though smaller or even so-called "nano particles" can be employed.

Particles may be food additives, seeds, additives to filters, such as zeolites or carbon black, and so on. Particles may be various synthetic, often polymeric materials. The present invention also provides particular benefits, when the particles are absorbent -9 -materials, or even more particular super-absorbent materials, such as well-known in the art.

For certain applications, the properties of the particles and of the web material may be optimized with regard to each other, such that, for example, particles may fit into fibrous interstices -or may not fit into, and remain on the surface of the web.

Densities of the particles may be described by the bulk density of the particle accumulation, such as may be determined as "tapped density", as a result of the particle material density, such as the polymer density in case of polymeric material, the particle size distribution and particle shape. The range of suitable bulk densities is not particularly limited, low values can be well below 100 kg/in3, such as 50 kg/m3, for example when porous materials are employed, often bulk densities range between 500 kg/m3 and 1000 kg/m3.

When combining particles and a web, the relative distribution is typically described by the term "basis weight", expressed in gram per square meter. Thus when particles are applied to a web which exhibits a given basis weight, the resulting particle loaded web will exhibit an overall basis weight as the combination of the basis weight of the web and of the particles.

It should be noted, that -unless expressly stated -within the present context the Cartesian system is also applied to surfaces of e.g. cylinders, which strictly speaking have a curvature. However, when the diameter of the cylinder is sufficiently large compared to the other geometries on the surface, e.g. an indentation towards the centre of the cylinder, it is considered a "z-directional" indentation, i.e. neglecting the curvature of the cylinder surface. Thus, a region may exhibit a z-directional extension, such as when an x-ydirectionally extending web is deflected z-directionally. Accordingly, the x-y-surface extends over the surface of such a cylinder.

The term "regions" refers to a geometric x-y-dimensionally extending area delimited by a circumscribing line, which may be a continuous or solid line or which may be a non-continuous line, such as a dashed or dash-dotted line. The circumscribing line may also result from two or more intersecting straight or curvilinear lines. Such a line may be physically present and/or he visible, or may be a thought line, such as when the region consists of two or more sub-regions, which can be circumscribed by an envelope line. An envelope line is the line around a set of sub-regions with the shortest line length. Regions or lines may also be essentially endless, such as is the case with a closed line on the surface of a cylinder.

Thus a first distinct regions in a particle loaded web material may differ from a second -10 -regions by a different amount of particulate material being added, such as may be expressed by a different particle basis weight in the first regions as compared to the second region. A first region may be delimited by an invisible circumscribing line around an accumulation of particles in or on the web, whilst a second region is essentially free of particles.

A region comprising particles may have various forms and shapes, such extending over the full width of the web or just be rectangular, circular, oval, or elliptically shaped, or may be irregularly shaped.

Two adjacent regions may have a sharp transition, such as when a particle free region is next to a particle loaded region. Also, the transition may be less sharp, such as when for a y-directionally even particle distribution the x-directional distribution follows a sinusoidal curve. In such a case, the borders of the regions Luc defined by the average value of the highest particle load and the lowest particle load, all expressed by the local basis weight The dimension of a region depend on the intended use, and will typically be more than 1 mm, often more than 5nun or 10 mm along any direction, but will be typically less than 800 mm, often less than 500 mm along any direction.

The distance between two neighbouring regions may typically be more than 5 mm, often more than 10 mm, but typically less than 300 mm, often less than 100 mm, and even less than 50 mm.

Generally, the amount of particles in or on the particle loaded web may be described by the particle basis weight.

However, the basis weight does not need to be constant over the full region, but there can be variations within the region, as can be determined by conventional methods such as weighing sectional regions, or x-raying, or under certain circumstances optically. If necessary, the basis weight distribution may be approximated by a smoothed curve when following a cross-sectional view through the particle loaded web, and thusly a local basis weight may be determined. If the local basis weight is determined by weighing sections of the particle loaded web, these section should not be smaller than lcm by 1 cm and care should be taken to not loose particulate material by this dissecting.

When a continuous particle loaded web is separated into a series of particle loaded web pieces, these pieces will exhibit a repeating pattern of regions with varying particle load. For example, if each of these pieces corresponds to an article, such as an absorbent article, these pieces may be separated by a cross-directional separation line, such as by cutting. Such a cutting operation is preferably executed in the absence of particles, as this might interfere with the cutting, or reduce life time of the cutting device, or result in -11 -losses of particles at the cut line. Henceforth, each of these pieces may comprise particle free leading and trailing sections, through which suitably can be cut.

Similarly, if longitudinal cutting of such a web is to be performed, the longitudinal side margins of the web, respective web pieces, may be formed by essentially particle free regions.

If both such particle free end and side margins were desired, these might be seen as a unitary particle free region circumscribing a particle loaded centre region.

Alternatively or in addition to the inclusion of particle free zones, the particle loaded regions may show varying amounts of particles.

Such an execution can be beneficial, when in a certain region of a web piece -or a corresponding article -more particles are desired than in another regions. Such designs are well known from absorbent articles, wherein superabsorbent particles are often accumulated in the crotch region of a wearer during use, whilst the front and rear portions of the article comprise less superabsorbent particles, and the front and trailing margins are essentially free of such particles.

The particles may exhibit a z-directional distribution profile. Thus, they may be z-directionally evenly distributed in the interstices of the web material, or they may rest on the surface of the web material, or -most typically -some of the particles will be distributed within the web material, some will remain on the surface from which they are applied, and some may even pass through the web and may be captured by a web supporting structure.

A particle loaded web travels with a web speed, expressed in e.g. m/sec. Thus also the particles in this web travel at the same speed. As will be described in more detail herein below, their x-directional basis weight profile changes for differing regions, and the corresponding particle mass flow along an x-coordinate fluctuates, too, even if the particle feed remains constant.

Thus, the present invention relates to an application system for applying particles to predetermined regions of a moving web, as well as a process for applying particles to predetermined regions of a web.

Figure 1 depicts schematically the set-up of an application system 100 according to the present invention for applying particles 1010 to a web 2010.

The system comprises a particle delivery system 1000 comprising a particle supply system 1100 comprising particles 1010, from which a flow of particles is fed to a divider unit 1500 via an inked piping 1200. The divider unit 1500 connects the infeed piping 1200 to a first (1700) and a second (1800) outlet piping, respectively, which further lead -12 -to a lay-down unit 3000, wherein in a first (3700) and a second (3800) lay-down zone, respectively, particles are applied to the web 2010. The web 2010 is provided from a web supply and transport system 2000 to the particle lay-down unit 3000, and after the particles are applied thereto the particle loaded web 2010' is delivered to further downstream handling 2900. Alternatively, the web may be an essentially endless support system, such as a belt system, on which a series of pre-cursors for an article are positioned to which the particles may be applied analogously.

The system is operated such that the particle loaded web comprises a first particle loaded region 2012, as created by applying particles in the first lay-down zone 3700 of the particle lay-down unit 3000, and a second particle loaded region 2018, as created by applying particles in the second particle lay-down zone 3800, whereby both zones are positioned x-directionally offset and separated by a separation zone 2015. When particles are applied to the web in the first particle lay down zone, this creates a first particle loaded region in the web, and when particles are applied to the web in the second lay-down zone, this creates a second particle loaded region in the web. The first and the second particle loaded regions in the web may have any relative positioning to each other, such as being partly or completely overlapping, or being separated, or being cross-directionally offset of each other, thereby forming a repeating patter 1 of regions in the web.

To this end, the divider unit 1500 is operated such that the inked particle stream through pipe 1200 is directed alternatingly to a first and a second piping system 1700 and 1800, or -at least for the switch-over period -split between the first and the second piping system.

Assuming for simplicity of the explanation a first execution, wherein the divider unit is operated such that the infeed stream is distributed instantaneously at even time intervals to the first and the second pining, further that the velocity of the particle streams (vi and v22) remains constant and equal to the inked particle velocity vi in both the first and the second piping, and the length of the first and the second piping (II and I,) is identical. Then, the residence time of the particles in the outlet piping Sto is equal to v",/ 11, or is equal to vp2 /12, respectively. Further, the spacing 3900 between the first and the second lay-down zones of the particle lay-down unit is denoted as "C", and the x-directional velocity of the web as v". Then the leading edge of the first particle loaded region of the web reaches the trailing portion of the second particle loading zone after a time differential of AM equal to v", / C. With appropriate selection of vp, 1, v, and C, the particle loaded regions 2012 and 2018 in the web may, for example, be at least partially -13 -coinciding and an essentially particle free region 2015 may be positioned between two such consecutive loaded regions along the web length.

For a further explanation by using a simplified execution, reference is made to 2A, depicting schematically the time line. Starting at an arbitrary point in time to, the divider unit diverts instantaneously (i.e. the time interval for opening the first piping Atdi, as well as the time interval for closing the second piping Atod are zero respectively negligible) the it-aced particle stream into the first piping for a time interval during which the first piping system remains unshut Atdi". The first particles will reach the first lay-down zone 3700 after the residence time Atid and are then traveling with the web at the web speed over the spacing C to the second particle lay-down zone 3800, reaching it at a time ti = to + Ato + Atc.

As the divider unit switches from the first piping to the second piping afterAtch" which also corresponds to the time during which the second piping is kept shut (i.e. Atic," particles will now run through the 2nd piping to the second lay-down zone, and the first particles will reach this at a time t, = to + At d2, + If it is desired to load a web region with a double amount of particles, ti and t, can be equated and appropriate selections for C, li and 12, v11 and vr, vw, and the interval times for keeping the first (Atdi") and second (Atdid) piping open, can be made to satisfy this equation.

The skilled person will readily realize how the various factors impact the timing and the longitudinal particle distribution pattern in the particle loaded web.

In Fig. 2B another simplified scenario for the time line of one operating cycle of the divider unit is schematically depicted for explanatory purposes. Therein, it is assumed that the infeed flow is split into the first and the second outlet flow at a percentage Pi (shown as solid line) and 132 (shown in dotted line), respectively, of the infeed flow Considering the diverter in a divider unit being at a constellation such that the first piping is shut, and the second piping is unshut. At to the diverter is actuated and the second piping is closing, which takes a time increment of Atd," whilst the first piping is opening, which takes a time increment Atdto = Atro. After the closing of the second respectively opening of the first piping, the full infeed stream is now diverted to the first piping.

After the unshut time Atdi", during which the full infeed stream is diverted to the first piping, the diverter switches back and starts closing the first piping. After the closing interval Atdic, which corresponds to the opening interval of the second piping Atd2o, the first piping is fully shut, and the second piping fully unshut, and a full diverter cycle is -14 -finished.

At a time to + Ato (i.e. the residence time of the particles in the first piping) the first particles reach the first particle lay down zone 3700 through the first piping and are applied to the web 2010, thereby forming the leading margin of the first particle loaded region of the web 2011 During the further time increment of fully opening the first piping, Atdio, (corresponding to the closing time interval of the second piping Atd,o), the infeed flow is split between the first and the second piping, here assumed as a linear time dependency of the opening. After that time increment, i.e. at a time of to + Ato + Atdio the full stream reaches the lay-down zone 3700. At a further time increment Atli, during which the full stream is running through the first piping, i.e. at a time (to + A1 Atdio + Atdio) the diverter is activated again and the particle stream through the first piping begins to lessen and is stopping at (to + A11 + Atdi0 + Atm, + Athe) until upon the rerun of the cycle the first particles of the next cycle arrive, such that during the time interval Atdis no particles arc applied to the web in the first lay-down zone.

Fig. 2C depicts the application of the particles to the web for a cycle as described for Fig. 2B as a function of the length of a web piece.

In the uppermost plot, the particle loading percentage relative to the particle infeed is plotted (with long dashes) against a length of a web running through the first particle lay down zone. Thus, for a web piece corresponding to an article length lA a repeating trapezoidal pattern is created.

Correspondingly, the second plot shows the complementing pattern (with short dashes) as created in the second lay-down zone, which is shown to be offset by the length separation zone C. The third plot shows these patterns next to each other in a single plot, whilst the fourth plot shows the cumulated percentage (as solid line) for the web piece with the article length 1A.

It can be clearly see, that for a certain region the percentage is doubled, whilst for another region the percentage may decrease to zero. Thus a profile and a particle free zone can be created simultaneously.

The skilled person will readily realize that a number of variants are included within the scope of the present invention, which may be applied in isolation or in combination with one or more of these variants.

The closing and the opening of a piping do not need to occur at constant speed, such that transition lines in the above plot may be non-linear curves.

The closing speed and the opening speed can be different, such that the transition lines -15 -lave different slopes.

A piping does not need to be fully closed, such that always a certain amount of particles is added via this piping, and the flow through the second piping is providing profiling to a continuous stream.

Whilst one diverter cycle has been described to correspond to an article (or precursor) length, two or more diverter cycles may correspond to one article.

As indicated in the above, the separation zone length C may be such that the particles as laid down in the first and second lay-down zone are applied to one and the same article, but C may he larger and optionally also additional web materials may be introduced between the first and the second lay-down zones.

The particle flow in any of the piping may be supported by a carrier flow, such as by the addition of pressurized air or application of a vacuum.

First and second piping may be straight or curved, constant diameter, rigid or flexible, same or different length. The cross-sectional shape of the piping is not critical, and may be rectangular, circular / elliptical, or of any other shape. It may even vary within a production cycle, e.g. in its width.

The particle lay-down zones may comprise suction areas, such that the particles are better held to the web or aided in penetrating into the web.

Whilst the above has been described by referring to a two-stream divider unit, the same principles can be readily applied to more than two piping from the divider unit to the more than two lay-down zones of the particle application unit. This will allow to create more sophisticated particle profiles over the length of the web.

The specific design of the divider unit is not critical for the present invention.

In a first, and often preferred exemplary execution, the divider unit may have the general shape of an inverted "Y", with one infeed and two outlets, and a diverter flap, which may be rotatably mounted around a horizontal axis (i.e., about perpendicular to the direction of flow) and be closing either the first or second outlet, and leaving both of them at least partly open during the switching operation.

This is further explained when considering an exemplary execution as shown in Fig 3, with Fig 3A and 3B showing two positions of the diverter flap.

The particles 1010 are provided from as particle delivery system 1100, here shown with a dosing system 1150 with two counter-rotating rolls 1152 and 1154, which form a dosing gap 1155. The particles flow gravity driven through an infeed piping, here shown as housing 1200 towards the divider unit 1500. The divider unit 1500 comprises a housing and an infeed opening 1512 for receiving the infeed particle stream as well as a first -16 - (1518) and a second (1519) opening for the first (1700) and second (1800) outlet piping, leading to the first (3700) and second (3800) particle lay-down zone, respectively, which are spaced apart by the spacing C. The divider unit further comprises a diverter flap 1600, which is rotatably mounted to rotate around a diverter flap axis 1610.

As indicated in Fig. 3A, the diverter flap closes the second opening whilst the first opening is fully open or unshut. Thus the particles are guided from the infeed towards the first outlet piping and further towards the first lay-down zone. Accordingly, in the process scenario as schematically shown in Fig. 3B, the diverter flap closes the first outlet opening and the particles are diverted towards the second particle lay-down zone 3800.

The diverter flap may be operated in a symmetrical modus, i.e. the opening and closing may be performed at equal and constant angular speed.

In an often preferred execution, the angular speed of closing the first and the second divider may be different, such that for example the closing of the second piping is slower than the closing of the first piping.

Further in Figure 3A and 3B it is schematically indicated, that the first and second outlet piping may comprise a particle carrier system, such as may he pressurized air, indicated by carrier flow 1920 as may be added through housing openings 1910.

In another execution, the diverter unit of the divider unit may he executed as a rotating nozzle system, as exemplarily depicted in Fig. 4, with other features as shown in Fig 3.

As the nozzle 1650 rotates around a vertical axis 1660 it distributes the particles through the infeed opening through the first outlet opening 151 8 into the first piping 1700 (see process scenario in Fig 4A) and through the second outlet opening 1519 into the second piping 1800 (see process scenario in Fig. 4B).

The diverter may be executed as a disk that is rotatably mounted around an axis essentially aligned with the direction of flow and that comprises one or more openings which thusly rotate over the outlet piping and the release the particles to the respective piping.

Another suitable diverter unit may be based on conventional sample divider equipment, such as Retsch Rotating tube divider PT 200, Sample divider PT100, or Fritsch Rotations-Kegelprobente i ler.

Optionally, the divider unit may comprise particle segregation means, such that larger particles or particles exhibiting a higher density are preferentially directed to one predetermined outlet.

The first, second, or further piping can create essentially cross-directionally identical lay-down patterns. However, it is also within the scope of the present invention, that the -17 -width or cross-directional position or shape of the lay-down pattern of the first, second or further lay-down zone vary or even window or frame like regions in the web may be created.

Having thus described the key features of the present invention, the application of such a process or such an equipment for the manufacturing of absorbent articles comprising superabsorbent particles may be a particularly preferred application, but this should not be seen to limit it thereto, but also any other application of particles to a moving web in a controlled manner is contemplated herein.

Claims (14)

1. -18 -Claims L A process for applying particulate material to a moving web to form a particle loaded web, the process comprising the steps of - providing a web supply and transport system; a particle supply system; a particle lay-down unit, 1 0 comprising a first and a second particle lay-down zone that are machine directionally offset at a separation zone length C greater than zero; a particle delivery system comprising a divider unit, comprising a housing, comprising an inlet, and at least a first and a second outlet, a diverter; inlet piping for delivering a particle stream from said particle supply to said divider unit; at least a first and a second outlet piping connected to said at least first and second outlet for delivering particles from said divider unit to said particle lay down unit, wherein said first outlet piping is designed to deliver particles to said first particle lay-down zone, and said second outlet piping is designed to deliver particles to said second particle lay-down zone; - feeding an infeed stream of particles from said particle supply of said particles to said -divider unit; - feeding said web at a web speed through said particle lay down unit; characterized in that it further comprises the steps of - operating said diverter of said divider unit such that for a first time interval a first percentage of said infeed particle stream is directed into a first outlet piping forming a first outlet particle stream and for a second time interval -19 -a second percentage of said infeed stream different to said first percentage is directed into said first outlet piping, whilst the respective remainder of said infeed particle stream is directed to said second outlet piping forming a second outlet particle stream; -feeding said first and said second outlet particle streams through said first or said second outlet piping, respectively, to said first or said second particle lay-down zone; - adjusting (i) the particle residence time of said particles in said first outlet piping and in said second outlet piping, and (ii) said zone separation length C. and (iii) said web speed, such that said particle loaded web comprises a repeating pattern of at least a first and a second region differing in amount / basis weight of particles applied thereto.
2. 2. A process for applying particulate material to a moving web according to claim 1, further comprising the steps of - providing a further lay-down zone; a further outlet of the divider unit; a further piping connecting said further outlet with said further lay-down zone designed to deliver particles to said further lay-down zone; - operating said diverter such that for a first time interval a first percentage of said infeed mu-dcle stream is directed into a first outlet piping forming a first outlet particle stream and for a second time interval a second percentage of said infeed stream different to said first percentage is directed into said first outlet piping, whilst the respective remainder of said infeed particle stream is directed to said second outlet piping or to said further outlet piping forming a second and a further outlet particle stream.
3. 3. A process for applying particulate material to a moving web according to claim 1 or 2.wherein one of said first or second or further regions is essentially free of particles.
4. 4. A process for applying particulate material to a moving web according to any of the preceding claims, further comprising the step of separating said web into web pieces, each comprising said repeating pattern of at least a first and a second region.
5. 5. A process for applying particulate material to a moving web according to any of the preceding claims, wherein said diverted is operated such that an outlet is fully closed whilst at least said second or a further outlet is fully open.
6. 6. A process for applying particulate material to a moving web according to any of claim 1 to 5, wherein said diverter comprises a hinged diverter flap positioned between a first and a second outlet, and said operating of said diverter comprises the step of moving said lunged diverter flap from a first position to a second position at a higher speed than when moving it from a second position to a first position
7. 7. A process for applying particulate material to a moving web according any of claim 1 to 5, wherein said diverter comprises a rotatably mounted diverter nozzle, and said operating of said diverter comprises the step of rotating said rotatably mounted diverter nozzle around an axis essentially aligned to the direction of the inked stream.
8. 8. A process for applying particulate material to a moving web according to any of claims 1 to 5, wherein said diverter comprises a rotatably mounted diverter tool and said operating of said diverter tool comprises the step of rotating said diverter tool at an angle relative to said rotating axis, such that its outlet diverts particles to said first or to said second or to said further outlet piping.
9. 9. A process for applying particulate material to a moving web according to any of claim 1 to 5, wherein said diverter comprises a rotatably mounted diverter disk comprising at least one diverter disk opening, -21 -and said operating of said diverter comprises the step of rotating said diverter disk such that said infeed particle stream is diverted through said diverter disk opening to said first or to said second or to said further outlet piping.
10. 10. A process for applying particulate material to a moving web according to any of the preceding claims, further comprising the step of providing a particle carrier medium, preferably air, to one or more of said inlet, first, second and further outlet piping for adjusting the particle residence time of said particles in said inlet, first, second or further outlet piping.
11. 11. A method for the manufacturing of a series of web pieces said process being characterized in that it comprises the steps of providing a particle loaded web according to any of the preceding claims; separating said particle loaded web into a series of web pieces, such that each of said web pieces comprises predetermined first and second regions.
12. 12. A method for the manufacture of a series of web pieces according to claim I I in a manufacturing process for forming absorbent articles.
13. 13. A system for applying particulate material to a moving web to form a particle loaded web, the system comprising a web supply and transport system; a particle supply system; a particle lay-down unit, comprising a first and a second, optionally a further particle lay-down zone that are machine directionally offset at a separation zone length C greater than zero; a particle delivery system comprising a divider unit, comprising a housing, comprising an inlet, and at least a first and a second and optionally a further outlet, a diverter, preferably selected from the group consisting of a hinged diverter flap; a rotatably mounted diverter nozzle; -22 -a rotatahly mounted diverter disk comprising at least one diverter disk opening, inlet piping for delivering a particle stream from said particle supply to said divider unit; at least a first and a second outlet piping connected to said at least first and second outlet for delivering particles from said divider unit to said particle lay down unit, wherein said first outlet piping is designed to deliver particles to said first particle lay-down zone, 1 0 and said second outlet piping is designed to deliver particles to said second particle lay-down zone; wherein said first outlet piping is adapted to deliver particles to said first particle lay-down zone, and said second or further outlet piping is adapted to deliver particles to said second or further particle lay-down zone, respectively, and wherein first and said second or further particle lay-down zones are machine directionally offset at a separation zone length greater than zero.
14. 14. An Equipment according to claim 13, wherein at least one of said outlet piping is flexibly adjustable in its length and/or machine directional positioning.