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  Process for producing sandwich structures with particulate material patternUSPTO Application #: 20060048880Title: Process for producing sandwich structures with particulate material pattern Abstract: The present invention is concerned with a process for forming a very well defined pattern of particulate material in a composite material comprising a web material and particulate absorbent material. The present invention relates also to a method for determining the equipment design and process parameter for such a process. In a particular application, the present invention provides a process for preparing liquid absorbent structures, such as may be useful for disposable absorbent articles. (end of abstract) Agent: The Procter & Gamble Company Intellectual Property Division - Cincinnati, OH, US Inventors: Horst Blessing, Hans-Adolf Jackels USPTO Applicaton #: 20060048880 - Class: 156060000 (USPTO) Related Patent Categories: Adhesive Bonding And Miscellaneous Chemical Manufacture, Methods, Surface Bonding And/or Assembly Therefor The Patent Description & Claims data below is from USPTO Patent Application 20060048880. Brief Patent Description - Full Patent Description - Patent Application Claims
FIELD OF THE INVENTION [0001] The present invention is a process for forming a very well defined pattern of particulate material in a composite material comprising a web material and particulate absorbent material. The present invention relates also to a method for determining the equipment design and process parameter for such a process. In a particular application, the present invention provides a process for preparing liquid absorbent structures, such as may be useful for disposable absorbent articles. BACKGROUND [0002] Composite structures comprising particulate material in a particular pattern are well known in the art, see, e.g. EP-A-1447066 (Busam et al.; P&G), disclosing an absorbent core for an absorbent article, which has a particulate absorbent material that is immobilized when wet. The absorbent core comprises a substrate layer an absorbent material, such as an absorbent polymer material. [0003] U.S. Pat. No. 4,381,783 (Elias) discloses an absorbent article with a core comprising pockets of absorbent hydrocolloid material. These pockets are provided to confine the movement of absorbent polymer material, in particular when the article is fully or partially loaded with urine. The pockets form part of an absorbent layer and are typically provided from cellulose material. Hence, as to achieve good immobilization of the absorbent polymer material according to the teaching of this patent relatively high amount of cellulosic material is required. Moreover, the provision of such pockets may hinder the free distribution of liquid to the more absorbent areas of the core, for example the areas of the absorbent polymer materials. [0004] Accordingly, processes to produce absorbent article having a non-homogeneous distribution of absorbent materials such as particulate absorbent polymer material, often referred to as absorbent gelling material or as super absorbents, are also known. In WO 03/101622A2 (Tombult et al.; P&G), a pulsing process for creating discontinuous particulate distribution is disclosed, and a similar structure may be produced according to U.S. Pat. No. 5,213,817 (Pelley; McNeill PPC). [0005] Processes aiming at depositing a pattern of particulate absorbent material onto a web are described in U.S. Pat. No. 4,800,102 (Takada; Nordson), employing a rotating mask, or in WO 92/019198A (Perneborn/Molnlycke) showing a linearly moving mask. FR-A-2583377 (Piron; Colgate Palmolive) discloses a metering drum into which absorbent powder is fed from a hopper for creating discontinuous pattern on a carrier on a conveyor belt. The drum is operated in a step-wise movement. [0006] U.S. Pat. No. 5,494,622 (Heath et al.; K-C), aims at producing pockets of particles in a desired pattern on a web moving at high speed. A pattern chamber is supplied with particles of high absorbency material through which a gas permeable web is transported on a surface having a pattern of openings through which a vacuum is drawn so as to cause the particles to be deposited on the web in the pattern of the openings in the surface. The web carrying the particles is covered by a layer of liquid permeable material and the tension applied to the permeable web is varied to vary the porosity of the web. The particles are held on the web in the desired pattern of pockets while surplus particles between the pockets are removed. The thusly formed pockets form "islands", i.e. they are completely surrounded by bonded regions. [0007] Whilst such documents describe various approaches to the deposition of particulate material onto a surface or on a moving substrate, there is still the need for a method to produce patterned particulate sandwiches in a very well defined pattern and at high production speeds. [0008] Further, whilst certain optimum conditions for each of these approaches may be read or deduced from the disclosures, there is no broadly applicable teaching as to how to arrive at the best suitable design with the best process settings, in particular for varying boundary conditions, like varying pattern, or lay-down basis weights, such as may be necessary for a complete product range. [0009] Applying mathematical modeling simulations for analyzing processes and/or process parameter are known in the art, such as from U.S. Pat. No. 6,529,860 (Strurnolo et al.; FORD). Therein, various computer related tools are employed to facilitate the design and testing of automotive vehicles, in particular with regard to investigate soil deposition on a vehicle panel. [0010] However, so far no solution has been provided for the simulation of a particle lay-down down system for forming particulate patterns, in particular not for application in the manufacturing of disposable absorbent articles. SUMMARY [0011] Thus in one aspect, the present invention is a process of creating a sandwich structure comprising particulate material sandwiched between web materials in a very well defined pattern. This process comprises the steps of [0012] creating such predetermined patterns in a pattern forming means on a transfer device, [0013] depositing the thusly formed patterns on a carrier web material, [0014] covering the pattern on this carrier material by a cover web material, [0015] and bonding the carrier and cover web material to form the sandwich structure, thereby immobilizing the pattern. [0016] To this end, there are provided: a particulate material; a transfer device comprising a first pattern forming means for receiving particulate material in a receiving region and transferring it to an discharging region, an essentially flat web material as carrier and/or cover material forming the outer layers of the sandwich; an essentially endless carrier support means for the carrier having a support pattern corresponding to the pattern of the first pattern forming means of the transfer device; a carrier material holding means for temporarily attaching the carrier material to the surface of the carrier support means; and sandwich fixation means for combining the sandwich structure [0017] The carrier and the cover material may be unitary for forming both outer sandwich layers or may be different materials forming the outer sandwich layers; [0018] The process further comprises the execution of the following steps: transferring the particulate material to the receiving region of the transfer device, whereby the first pattern forming means defines a particulate cluster pattern; moving the pattern of particulate material to the discharging region of the transfer device; guiding the carrier web material over the carrier support means at a carrier speed corresponding to the carrier support speed; deforming the carrier web material by the carrier material holding means such that an indentation is formed in the unsupported regions, thereby forming a pattern corresponding to the particulate cluster pattern; expelling the particulate material from the transfer device towards the carrier; depositing the expelled particulate material on the deformed web carrier material; applying the cover material to the carrier material and the patterned particulate material, thereby forming a sandwich structure, providing fixation means for bonding the outer sandwich layers to each other at least in parts of the bonding area. [0019] In a further aspect, the present invention is a method for determining the equipment design and process parameter for a process for selectively positioning particulate material onto a moving surface, by [0020] 1) providing a set of physical equations forming a physical model, the set of physical equations being connected by interaction boundary conditions, optionally comprising sub-models connected by sub-model connectivity boundary conditions, [0021] 2) selecting a set of fixed boundary conditions, comprising the overall equipment set-up, overall process requirements, and a set of (initial) operating conditions (fixed model input), [0022] 3) providing a set of predetermined model targets, [0023] 4) selecting a set of variable boundary conditions, which may vary throughout one simulation (variable model input), [0024] 5) performing calculus operations on the physical equations by using the fixed and variable model input, [0025] 6) transforming the calculus results into a model output, which is readable to a human analyst directly or preferably by a means of a computing device; [0026] 7) comparing the model output to predetermined model targets and determining the deviation there between, [0027] 8) modifying the set of variable boundary conditions, [0028] preferably by using computational equations for minimizing the deviation between the model output to predetermined model targets; [0029] 9) reiterating steps 4) to 8) until a preset exit criterion is met. [0030] Preferably, these steps are performed by employing a computer device. The iterations may be terminated by defining a preset number of iterations of by defining a preset exit deviation criterion between the model output and the predetermined model targets. [0031] In yet another aspect, the present invention is a system for determining the equipment design and process parameter for a process for selectively positioning particulate material onto a moving surface, the system comprising a memory device and a processor, disposed in communication with the memory device, the processor being configured [0032] a) to receive virtual simulation programs and overall boundary conditions; [0033] b) simulation targets; [0034] c) and simulation starting parameter [0035] so as to calculate a set of pre-defined output parameter and to transmit the output parameter to an output device. BRIEF DESCRIPTION OF THE FIGURES [0036] FIG. 1 is a top plan view of a disposable diaper, with the upper layers partially cut away. [0037] FIG. 2 shows a cross-sectional view of the disposable diaper of FIG. 1. [0038] FIG. 3A shows a top view of an absorbent core sandwich structure. Continue reading... Full patent description for Process for producing sandwich structures with particulate material pattern Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Process for producing sandwich structures with particulate material pattern patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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