Patent Application
20090033495
This invention relates to molded products with in-mold RFID labels and methods of in-mold labeling.
An RFID label is a smart label that could be used for various purposes such as the identification and tracking of goods. Molded products, such as containers in a warehouse and plastic bins in a manufacturing facility, may require an RFID label because the containers have to be identified in the warehouse and the plastic bins have to be tracked during the manufacturing operation. This can be accomplished by either attaching the label to the surface of the product via an adhesive or fastener solution or by embedding the label into the molded product. Attaching an RFID label to a product using an adhesive or a fastener has the risk of the label separating from the product. The labels in this scenario are not flush with the surface and therefore are subject to various environmental hazards that can cause separation. By making the label an integral part of the molded product and flush with the surface, the chances of the label separating from the product are minimal. Molded labels are useful in creating a discrete, permanent identification method for the plastic molded products.
An RFID inlay or label generally comprises a chip or a “strap” connected to antenna disposed on a substrate made of polymers such as polyethylene terepthalate (PET). RFID labels having a substrate made of material such as PET may be difficult to embed in a plastic product because the PET resin does not bond well with high density polyethylene (HDPE), a resin that is commonly used in the manufacture of molded plastic products such as bins, pallets, and containers. If the RFID label does not bond well with the bulk material, such as HDPE used to make a plastic product, the label may not remain a part of the molded product.
This invention relates to molded plastic article having an in-mold label comprising an RFID device, and method of in-mold labeling. In one embodiment of the invention, the label comprises an RFID inlay and a substrate made of a polymer material such as PET underneath the RFID inlay. The substrate including the RFID inlay is chemically primed, and then covered with a polymer such as low density polyethylene (LDPE) resin. Many injection molded products are made from HDPE. The LDPE resin that covers the label can bond with the HDPE resin that is injection molded because they are chemically similar substrates, but the PET and the HDPE are dissimilar resins and do not bond. Because the LDPE covering allows for adhesion of the PET substrate of the label with the dissimilar HDPE resin, the LDPE covering makes the RFID label amenable for inclusion in an injection molded HDPE product
The embodiments of in-mold RFID labels have various configurations. The configurations comprise:
Label before in-mold inclusion in a product:
Label after in-mold inclusion in a product:
The term “label” as used here refers to a label, tag or ticket. The term “Radio Frequency Identification” or RFID as used here refers to device that receives or transmits data by radio frequency. The RFID device is of any conventional construction and inlays suitable for use in the present invention are produced as described in U.S. Pat. No. 6,951,596. The term RFID label refers to a label that includes an RFID device. The present invention, in one embodiment, relates to the discovery that an RFID label when covered with a polymeric resin that is chemically compatible with the polymer used for making a molded product makes the RFID label amenable for inclusion in the molded product. In a further embodiment, the RFID label covered with a polymeric resin is placed inside a mold and the polymer injected into the mold to form the molded product.
After the application of the primer 140, the RFID label is covered with a polymer 170 using well known techniques such as extrusion and coating. In one embodiment, the polymer 170 is LDPE. In another embodiment, the polymer 170 is polypropylene (PP). In a further embodiment, the polymer 170 is ethyl vinyl acetate (EVA). The polymer 170 can also be mixture of polymeric resins such as LDPE and PP. Slot Die coating is a basic method of applying molten polymeric resin to a substrate. A coating liquid is forced out from a reservoir through a slot by pressure, and transferred to a web. Slot Die coating is a coating with a die against a web. Practical considerations for use of slot die as a coating method are geared to quality needs, e.g., performance, uniformity of coating thickness, freedom from defects, and a uniform surface finish with the desired characteristics.
In other embodiments of the present invention, primer is not be used and the polymer is directly applied to the RFID substrate, the RFID chip and/or the antenna. In a further embodiment of the present invention, an adhesive layer is disposed as the top or uppermost layer of the in-mold labels. In another embodiment, the adhesive layer is disposed over outer or exposed surface of the polymer layer. The adhesive layer partially or fully covers the polymer layer. The adhesive layer permits the attachment of the in-mold label to an interior surface of the mold, which prevents the label from displacing or distorting prior to or during the molding process. Any adhesive which is capable of adhering the label to an interior surface of the mold as the molding process is initiated can be utilized. Suitable commercially available adhesives are sold by such commercial sources as Beacon Chemical Company, Inc., Acheson Colloids, Quretech and Northwest Coatings. Examples of such adhesives are Magnacryl 2793 (Beacon), ML 25184 (Acheson), JRX-1068 (Quretech) and U.V.-curable-10152 (Northwest). Other examples of adhesives available from Beacon Chemical Company include Magnacryl UV 2601 Epoxy, Magnacryl 2296, and Magnacryl 2807. Another example of a useful commercially available adhesive material is Rad-Cure UV 1008 (a product of Rad-Cure Corporation identified as a U.V. curable, solvent-free adhesive containing 70-95% w multifunctional acrylate monomers, 5-20% w photoinitiator and 0-5% w surfactants.). In yet another embodiment, the in-mold label of the present invention comprises a carrier which is a release-coated liner having one surface (the release-coated surface) in contact with the otherwise exposed upper surface of the adhesive layer. The carrier is used to protect the upper surface of the adhesive layer during preparation, handling, storage and shipping of the labels. The carrier is removed from the label prior to positioning and adhering the label to an internal surface of the mold. The release-coated liner may comprise a substrate sheet of paper, a polymer film or combinations thereof coated with a release composition.
The following examples describe the various embodiments of the present invention. Numerous modifications and variations within the scope of the present invention will be apparent to those skilled in the art and the present invention is not limited to the examples given below.
Inlay stock was coated with primer as shown in
Inlay stock was coated with primer as shown in
The primer used in Examples 1 and 2 is a water-based primer MICA available from Mica Corporation, Shelton, Conn. The water-based primer MICA is non-adhesive, and was utilized to promote chemical bonding of the LDPE resin with the RFID substrate.
Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.
