Abstract:
A method of manufacturing a consumable product marker for use in the food or pharmaceutical industry is disclosed. The product marker is configured to be consumed along with products into which the product marker has been incorporated. The product marker comprises at least one identification opening extending through the product marker. The method of manufacturing the product marker includes extruding a polymeric elongate precursor marker structure defining a cross-width, cooling the extruded precursor marker structure to set an extruded shape of the precursor marker structure, and cutting the precursor marker structure to form a plurality of product markers. A draw-down process may be used during the extrusion process to reduce the cross-width of the precursor marker structure.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]     This application claims the benefit of U.S. Provisional Application Ser. No. 60/758,459, filed Jan. 12, 2006, which application is hereby incorporated by reference in its entirety. 
     
    
     TECHNICAL FIELD  
       [0002]     The present invention relates generally methods for manufacturing products using extrusion techniques. More particularly, the present invention relates to methods for manufacturing product identifier markers using extrusion techniques.  
       BACKGROUND  
       [0003]     Product markers are small elements that can be incorporated into products such as pharmaceuticals or food products to allow the origin of the products to be readily confirmed. U.S. Pat. No. 6,951,687, which is hereby incorporated by reference in its entirety, discloses example product marker configurations.  
         [0004]     Product markers used in the food and pharmaceutical industries are typically intended to be consumed along with the products into which they have been incorporated. It is preferred for the markers not to affect the flavor or texture of the products into which they have been incorporated. This being the case, product markers are generally small in size. Additionally, the markers are typically manufactured to relatively close tolerances and often have fairly intricate shapes or patterns incorporated therein. The above factors make the effective mass production of product markers a difficult endeavor.  
       SUMMARY  
       [0005]     One aspect of the present disclosure relates to methods and systems for efficiently manufacturing product markers.  
         [0006]     A variety of additional inventive aspects will be set forth in the description that follows. The inventive aspects can relate to individual features and to combinations of features. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the broad inventive concepts upon which the embodiments disclosed herein are based. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]      FIG. 1  shows an example identifier marker;  
         [0008]      FIG. 1A  shows a side view of the marker of  FIG. 1 ;  
         [0009]      FIG. 2  is a flow chart showing an example manufacturing sequence having inventive aspects in accordance with the principles of the present disclosure;  
         [0010]      FIG. 3  is a high-level schematic diagram of a system in accordance with the principles of the present disclosure for manufacturing product identifiers;  
         [0011]      FIG. 4  is a cross sectional view of an extrusion device having inventive aspects in accordance with the principles of the present disclosure;  
         [0012]      FIG. 5  is a cross sectional view taken along section line  3 - 3  of  FIG. 4 ; and  
         [0013]      FIG. 6  is a schematic diagram of a conventional draw tower. 
     
    
     DETAILED DESCRIPTION  
       [0014]     The present disclosure relates generally to systems for manufacturing relatively small identifier markers. Example identifier markers are disclosed in U.S. Pat. No. 6,951,687, that was previously incorporated by reference.  FIG. 1  shows one example type of identifier marker  20  that can be manufactured in accordance with the methods disclosed herein. The marker  20  includes a plurality of openings  22  that extend through the marker. It will be appreciated that the size, position and number of the openings can be used as a means for identifying the marker.  
         [0015]     According to certain preferred embodiments of the markers  20 , the maximum distance D across the marker face  21  (i.e., the maximum diameter) is between 0.5 micrometers and 5 millimeters. More preferably, the maximum distance is between 1 micron and 1 millimeter, and even more preferably between 10 micrometers and 250 micrometers. Most preferably, the maximum distance across the face  21  of the markers  20  is between 30 micrometers and 100 micrometers.  
         [0016]     According to still other certain embodiments, the maximum distance across the face  21  of the markers  20  is less than 500 micrometers. More preferably, the maximum distance is less than 300 micrometers, and even more preferably less than 100 micrometers. Most preferably, the maximum distance across the face  21  of the markers  20  is less than 40 micrometers.  
         [0017]     The maximum thickness T of the markers  20  (i.e. the maximum distance between a front face  21  and a back face  23 ) may be any value suitable for the intended use of the markers  20 . Accordingly, one skilled in the art may determine such values empirically and can vary such values as appropriate based on the intended application thereof.  
         [0018]     According to certain preferred embodiments, the maximum thickness T of the markers  20  is between 0.5 micrometers and 100 micrometers. More preferably, the maximum thickness is between 0.5 micrometers and 50 micrometers, even more preferably between 1 micrometers and 20 micrometers and still even more preferably between 1 micron and 10 micrometers. Most preferably, the maximum thickness of the markers is between 3 micrometers and 5 micrometers.  
         [0019]     In certain embodiments, an aspect ratio of the mean distance D across the face  21  to the mean thickness T of between 1:1 and 200:1 is possible.  
         [0020]      FIG. 2  is a flow chart showing an example processing method in accordance with the principles of the present disclosure for manufacturing identifier markers. At operation  30  of the process, an elongate precursor marker structure is extruded. The elongate precursor marker structure may include a desired pattern of openings formed therein and may also include a desired pattern or contour provided about the perimeter of the precursor marker structure. The extrusion operation may include a draw-down process to reduce the cross width (e.g., the outer diameter) of the precursor marker structure. Typical draw down ratios as part of the extrusion process may be from about 5:1 to about 25:1. After operation  30 , the precursor marker structure is cooled at operation  32  to set the extruded shape of the precursor marker structure. Thereafter, the cross-width of the precursor marker structure can be further reduced at operation  34 . In one embodiment, operation  34  can include a draw tower (see  FIG. 6 ) at which the precursor marker structure is re-heated and further elongated to reduce the cross-width to a final desired cross-width dimension. Once the final cross width has been set, the precursor marker structure is divided at operation  36  (e.g., sliced, cut, sheared or otherwise separated into multiple pieces) to provide a plurality of separate identifier markers each having the same outer cross sectional shape and the same pattern of openings formed therein. In preferred embodiments, the precursor marker structure is sliced along planes generally perpendicular to a longitudinal access of the precursor marker structure.  
         [0021]     Any suitable polymer, natural or synthetic, which has the desired characteristics for the intended applications of the identifier marker  20  can be used to manufacture the markers  20  through extrusion. Suitable polymers for use in the production of the markers  20  include biodegradable polymers and non-biodegradable polymers, water-soluble polymers and water-insoluble polymers, organic solvent-soluble polymers and organic solvent-insoluble polymers, natural polymers and synthetic polymers, and edible polymers and non-edible polymers.  
         [0022]     Certain specific examples of suitable polymers for use in the manufacture of the markers  20  include, but are not limited to, polylactide, hydroxypropyl cellulose, hydroxyethylcellulose, carboxymethyl cellulose, ethyl cellulose, starch, chitin, silk, zein, acrylonitrile-butadiene-styrene, polymethylmethacrylate, polyhydroxyethylmethacrylate, cellulose acetate, cellulose acetate butyratc, cellulose acetate propionate, polycarbonate, polystyrene, polyvinyl acetate, polyvinyl alcohol, styrene-acylonitrile, unplasticised (rigid) polyvinyl chloride, plasticised (flexible) polyvinyl chloride, high impact polystyrene, polyoxymethylene, polyformaldehyde (polyacetal), ethylene vinyl acetate copolymer, polyamide (nylon), polyethylene terephthalate (polyester), polybutylene terephthalate, low density polyethylene, linear low density polyethylene, high density polyethylene, polypropylene, poly 4-methyl pentene, polytetrafluoroethylene (ptfe), polyvinylidene fluoride (pvdf); and co-polymers or mixtures of any two or more thereof. Preferably the most suitable materials include pvdf or ptfe.  
         [0023]     Preferred mixtures of polymers include mixtures of lower and higher molecular weight polymers and/or mixtures of D- and L-isomers of the same or different polymers, which may, for example, affect the melting point or optical properties of the polymer.  
         [0024]     The polymers that are useful with extrusion processes include thermoplastics, elastomers before crosslinking, and thermosets before crosslinking. Thermoplastics include polyesters, polyamides, polyethers, polyolefins, halogenated polyolefins, fluorinated polyolefins, thermoplastic polyimides, poly(imide-ethers) and polycarbonates, and the like. Polymers which are extruded may also contain the usual additives such as fillers, reinforcing agents, antioxidants, colorants, pigments, etc. Exemplary of these are carbon black, glass fiber, clay, mica, graphite fiber, titanium dioxide, carbon fibers and natural fibers.  
         [0025]     At operation  30  of the process, an elongate precursor marker structure is extruded to a cross-width of between 1 cm and 5 cm. As discussed previously, this extrusion operation  30  may include a draw-down process to further reduce the cross width (e.g., the outer diameter) of the precursor marker structure at a ratio of about 5:1 to about 25:1. Operation  30  is preferably a vertical extrusion process.  
         [0026]     After operation  30 , the precursor marker structure is cooled at operation  32  to set the extruded shape of the precursor marker structure. Thereafter operation  30  and  32 , the cross-width of the precursor marker structure can be further reduced at operation  34 . Operation  34  involves utilizing a draw tower to further reduce the cross-width of the extruded precursor marker structure.  
         [0027]     Referring to a schematic diagram in  FIG. 6 , in a draw tower  115 , the lower end of the preformed extrude is slowly fed into a furnace where it turns into a molten state. The formed molten gob falls down under the force of gravity while shrinking in diameter into the proper desired width. The diameter is normally controlled continuously during the drawing process. The draw-down ratio may be typically from 100:1 to 1000:1. Other ratios are also possible depending on the end width required. Despite tremendous reduction in cross-sectional area, the relative geometrical profile of the marker remains unchanged.  
         [0028]     In certain applications, in a typical draw tower, the drawn polymer may be threaded through a series of coating applicators immediately after drawing. Liquid prepolymer coatings may be cured by thermal or ultraviolet apparatuses. A device such as a laser device immediately below the furnace may measure the diameter of the drawn polymer and any deviation from the programmed value is corrected by minute adjustments of the drawing speed.  
         [0029]     Example draw towers are available from Corning Incorporated, Draka Fibre Technologies, and Delachaux. Since the configuration and the operation of such draw towers are known in the art, further details thereof will not be provided herein, it being understood that those skilled in the art understand the nature of such an apparatus.  
         [0030]      FIG. 3  is a schematic diagram showing an example system in accordance with the principles of the present disclosure for manufacturing identifier markers. The system  100  includes a crosshead  102  that receives thermoplastic material from an extruder  104  (e.g., an auger style extruder or other type of extruder). A conveyor  108  conveys material (e.g., thermoplastic material in pellet form, fillers or other materials) to a hopper  106  that directs the material into the extruder  104 . The extruder  104  is heated by a heating system  112  that may include one or more heating elements for heating zones of the extruder as well as the cross head to desired processing temperatures. The extruder  104  functions to heat and masticate the thermoplastic material, and also provides pressure for forcing the thermoplastic material through the crosshead  102 . The cross head  102  may include tips and dies configured to impart a desired cross sectional shape to the material being conveyed through the cross head  102 .  
         [0031]     Referring still to  FIG. 3 , a cooling structure  116  (e.g., a liquid bath such as a water bath) is located downstream from the crosshead  102 . The cooling tank functions to cool the extruded product so as to set the cross sectional shape of the product. After cooling, a draw tower  115  can be used to further reduce the cross-width of the product extruded from the crosshead  102  as discussed previously. Once the product is drawn to the desired size, a divider  119  is used to divide the product into a plurality of separate, identical identifier markers.  
         [0032]     The drawn product may be cut into a plurality of markers by any of the methods and techniques known to those skilled in the art. Preferably, the primary polymeric fiber is cut with a microtome or guillotine-type device. In other embodiments, other cutting methods include mechanical cutting techniques, laser cutting, etching, or other techniques.  
         [0033]     Referring to  FIG. 4 , an example cross head  102  for vertically extruding a precursor identifier marker structure is shown. The cross head  102  includes a main body  200  that receives viscous thermoplastic material from the extruder  104 . A die member  202  mounts to the lower end of the main body  200 . The die member  202  includes an interior shape  204  that corresponds to the desired outer shape of the precursor marker structure extruded from the cross head  102 . The cross head  102  also includes a tip arrangement  206  that mounts to a top end of the main body  200 . The tip arrangement  206  includes a mounting plate  207  secured to the top side of the main body  200 , and a plurality of tip member  208  that extend downwardly through the interior of the main body  200  and into the die member  202 . Preferably, lower ends of the tip members  208  are vertically offset a distance D from the lower end of the die member  202 . The tip members  208  are sized, positioned and numbered so as to correspond to the pattern of openings desired to be provided in each of the identifier markers.  
         [0034]     It will be appreciated that the crosshead  102  can be used to manufacture markers having different hole patterns and different exterior shapes. To accommodate this, the cross head  102  can be used with a plurality of different dies and a plurality of different tip configurations. For example, the die  202  is configured to provide a generally circular outer shape to the precursor marker structure. If it is desired to have a marker with a tabbed outer shape, the die member  202  could be replaced with a die member  202 ′ having an inner surface that includes a tabbed configuration. Other die shapes can also be used.  
         [0035]     Similarly, the tip mounting configuration  206  can be replaced with other tip mounting configurations having different numbers of tips, different sizes of tips, and tips with different cross sectional shapes, and tips positioned in different locations. In certain embodiments, the tip mounting plate may have a plurality of openings into which tips can be inserted to provide a desired hole pattern. When the holes are not occupied by tips, the holes can be plugged. In certain embodiments, the tip mounting plate  207  can include a matrix of openings (e.g., a 10 by 10 matrix). By mounting tips in certain openings of the matrix and plugging the other openings of the matrix, different hole patterns can be generated. Some example tip mounting plate embodiments can accommodate at least 50 tips, or at least 100 tips. The pins may be temporarily clamped, screwed, fastened, or otherwise secured to the tip mounting plate.  
         [0036]     It is preferred for the tip member  208  to be hollow so as to define an air passage that extends from the top to the bottom of the tips. During extrusion, air can be pumped through the air passages of the tips and into the channels formed in the precursor identifier marker structure. In this way, the air within the channels of the precursor identifier marker structures assist in preventing the extruded channels from closing after the extruded material flows below the tips. In a preferred embodiment, air is provided through the tips on a mass-flow basis dependent upon the rate of extrusion. Example tips may have outer diameters ranging from 0.025-0.075 inches.  
         [0037]     It is preferred for the air flow rate of each of the tips to be individually controlled. For example, separate air mass flow controller can be provided for each tip. In certain embodiments, tips closer to the central longitudinal access of the product being extruded from the cross head  102  may require higher air flow rates as compared to tips that are farther offset from the center longitudinal access of the product being extruded through the cross head  102 . The separate mass flow rate controllers allows the air flow rate to be customized to optimize performance.