Stock material or miscellaneous articles – Structurally defined web or sheet – Including variation in thickness
Reexamination Certificate
2001-02-07
2003-03-11
Loney, Donald J. (Department: 1772)
Stock material or miscellaneous articles
Structurally defined web or sheet
Including variation in thickness
C428S095000, C428S166000, C428S167000, C428S188000
Reexamination Certificate
active
06531206
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to microstructured films and tapes that have the capability to acquire liquids and to control the directional transport of such liquids for subsequent removal. This transport can be passive or active (i.e., enhanced by an applied potential), and the invention has utility in a number of industrial applications and assemblies.
The collection of liquid in industrial applications (e.g., spills, condensate, ink, pooled fluids, etc.) can cause subsequent problems if the liquid is allowed to remain over a period of time. Some liquid management problems lead to corrosion, power supply loss, excessive weight retention, loss in efficiency, insufficient energy usage, safety hazards, and the like.
Current methods of liquid control focus on the prevention of liquid buildup on a surface through approaches such as absorbent materials, protective films and tapes, and sealants. None of these methods, however, provide for effective liquid removal once liquid is present on a surface.
Transport of liquid across a structured surface may be characterized based upon the mechanism that causes flow of the liquid. Where liquid transport pertains to a non-spontaneous liquid flow regime wherein the liquid flow results, for the most part, from an external force applied to the structured surface, such a liquid transport mechanism is considered “active”. On the other hand, where the liquid transport pertains to a spontaneous flow regime wherein the liquid movement results without the introduction of external forces, such a liquid transport mechanism is considered “passive”.
Active liquid transport products have been developed based upon specific applications, including absorbent pads or a liquid pervious layer combined with liquid transport devices. For example, mat products including active liquid transport and absorbent pads or liquid pervious layers are described in U.S. Pat. No. 5,437,651 to Todd et al. and U.S. Pat. No. 5,349,965 to McCarver. In each case, channels are defined on a surface of a substrate to direct liquid flow from substantially all of the area of a liquid pervious layer. These products remove liquid while having the liquid pervious layer act as a liquid adsorbing and storing layer and/or to define a liquid receiving layer. In Todd et al., a flexible backing plate is attached to an absorbent portion and a suction source is applied to the backing plate. The backing plate comprises a plurality of channels for directing the vacuum provided by the suction source more evenly across the surface of the absorbent portion. In McCarver, a flexible pad or suction rail having a liquid permeable top surface and a liquid impermeable bottom surface is connected to a vacuum source. The suction draws liquid down into a liquid receiving chamber as it passes through the liquid pervious layer, and draws the accumulated liquid away. The liquid receiving chamber contains separation means dividing the chamber into channels for keeping the chamber from collapsing when the chamber is placed under a negative pressure.
Another flexible liquid transport product is commercially available under the trademark “Fluid Control” floor suction mat, from Technol Medical Products Inc. This product is used to adsorb fluids that fall from a surgical site during a surgical procedure. The device has an absorbent mat that resides above a multitude of parallel and closed channels. Holes are provided in the channel surfaces that interface with the absorbent mat so that fluid recovered by the mat can be drawn into the channels. The parallel channels are connected to a manifold for attachment with suction tubing. Thus, after fluid has accumulated within the mat, removal thereof can be facilitated through the multiple channels by the application of a vacuum.
A fluid guide device having an open structure surface for attachment to a fluid transport source is described in U.S. Pat. No. 6,080,243 to Insley et al. This reference discloses an open structured surface that defines plural channels and a slot for permitting fluid communication between a distribution manifold and at least a plurality of the channels. A fluid transport source, such as a vacuum generator, is connected to the distribution manifold.
Examples of flexible fluid transport devices that utilize both active and passive fluid transport are described in U.S. Pat. No. 3,520,300 to Flower, U.S. Pat. No. 4,747,166 to Kuntz, and U.S. Pat. No. 5,628,735 to Skow. Examples of other channeled mats for fluid removal are shown in U.S. Pat. No. 4,533,352 to Van Beek et al. and U.S. Pat. No. 4,679,590 to Hergenroeder. Examples of passive fluid transport devices having channeled fluid transport structures are described in U.S. Pat. No. 5,514,120. This reference discloses the use of a liquid management member having a microstructure-bearing hydrophilic surface, preferably in combination with a liquid permeable top sheet, a back sheet, and an absorbent core disposed between the top and back sheets. The liquid management member promotes rapid directional spreading of liquids and is in contact with the absorbent core.
SUMMARY OF THE INVENTION
The present invention provides for active and passive transport for liquid acquisition and/or removal in industrial assemblies and applications using microstructured liquid control films.
The liquid control film may be incorporated to transport a liquid to a remote site, to collect a liquid on the film itself, or to disperse the liquid over an increased surface area to promote more rapid evaporation. The microstructured surface has a microstructured topology, and in preferred embodiments is a suitable hydrophilic, polymeric and flexible film. The film properties are described in terms of structure and material.
In one embodiment, the invention is a laminate liquid disposal assembly which includes a liquid control layer and a substrate layer. The liquid control layer has a top side and a bottom side, with the top side having a liquid landing zone for receiving liquid thereon and a liquid removal zone. The top side also has a microstructure-bearing surface with a plurality of channels thereon that facilitate directional flow control of the liquid across the top side from the liquid landing zone to the liquid removal zone. The laminate liquid disposal assembly includes means for attaching the bottom side of the liquid control layer to the substrate layer, and means for removing the liquid from the liquid removal zone on the top side of the liquid control layer.
A porous cap layer may be disposed over the landing zone on the top side of the liquid control layer. Further, the channels on the microstructure-bearing surface have channel ends, and the removing means preferably withdraws the liquid from the channels adjacent one of the channel ends thereof In another embodiment, the removing means withdraws the liquid from the channels adjacent both channel ends thereof. The removing means may include an absorbent material disposed in communication with the liquid removal zone. The removing means may also include a fluid collection manifold in communication with the channels in the liquid removal zone, and the removing means may further include a vacuum generator in fluid communication with the fluid collection manifold. In one embodiment, the removing means includes a liquid drip collector. In a preferred embodiment, the liquid control layer is a polymeric film, which may include a characteristic altering additive or surface coating. That additive may be selected from the group consisting of flame retardants, hydrophobics, hydrophylics, antimicrobial agents, inorganics, metallic particles, glass fibers, fillers, clays and nanoparticles.
In another embodiment, the invention is a laminate floor assembly which includes a liquid control layer and a floor substrate layer. The liquid control layer has a top side and a bottom side, with the top side having a microstructure-bearing surface with a plurality of channels thereon that facilitate directional flow control of a liquid disposed thereon. The laminate floor a
Castiglione Stephanie B.
Huntley Douglas A.
Johnston Raymond P.
Mortenson Sara B.
3M Innovative Properties Company
Loney Donald J.
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