Plastic and nonmetallic article shaping or treating: processes – With severing – removing material from preform mechanically,... – Punching article from sheet material
Reexamination Certificate
1995-04-07
2001-04-24
Silbaugh, Jan H. (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
With severing, removing material from preform mechanically,...
Punching article from sheet material
C264S176100, C264S300000, C264S328100, C264S331110
Reexamination Certificate
active
06221296
ABSTRACT:
FIELD OF THE INVENTION
The invention relates in general to information cards such as credit cards, debit cards, personal I.D. cards, employee passes, door and gate opening magnetic keys, etc. More particularly, this invention relates to a method of making magnetically encodable information cards of solid plastic, having magnetic particles uniformly distributed throughout the plastic.
BACKGROUND OF THE INVENTION
Identification cards such as credit cards, debit cards, personal identification cards, employee passes, and the like, have typically contained a magnetic stripe on the back, to record unique information about the owner of the card. Such information can include the credit or debit card number, a personal identification number, an employee number, as well as other information relating to the person and to the application of the card. It can also contain encoded information to cause doors or gates to unlock or open. One disadvantage of using a magnetic stripe is that it is clearly visible and easy to change or erase the recorded information. Another disadvantage is that continued use of the card by swiping of the magnetic stripe through a reader causes degradation of the magnetic stripe and information recorded thereon. A further disadvantage is the limited recording capacity of the single magnetic stripe.
There is thus a need to provide a method of making a magnetic information card having magnetic particles uniformly dispersed throughout without interfering with the neutral reflection density of the card without the presence of the magnetic particles.
SUMMARY OF THE INVENTION
According to the present invention, there is provided a method of making a magnetically encodable card having ferromagnetic particles uniformly dispersed throughout by forming a dispersion of ferromagnetic particles in an organic fluid medium, intimately combining the dispersion with a thermoplastic resin, the thermoplastic resin being plasticized by the organic fluid medium to form a composite, and fabricating the composite into a magnetically encoded card. According to still another aspect of the present invention, the magnetically encodable card also may have dispersed therein various materials such as, abrasive particles, lubricants, dyes, and pigments that provide a reflective background so that pictorial information can be printed on a face of the card.
DESCRIPTION OF PREFERRED EMBODIMENTS
Thus, the invention contemplates a method of making magnetically encodable cards by the steps outlined above. These cards, because of their nature, demonstrate improved endurance over prior art cards in that they do not delaminate, the magnetic signal is not diminished as a result of abrasion due to multiple passes through readers, and that the information can be encoded into the card in any desired direction or configuration as the magnetic particles are uniformly dispersed throughout.
By “uniformly dispersed throughout” is meant that the signal envelope of the card is as described in copending U.S. patent application Ser. No. 08/418,336 filed Apr. 7, 1995. by T. Jagielinski, F. Jeffers, and R. O. James, and commonly assigned.
The phrase “uniformly dispered throughout”, as applied to the card made by the process of this invention, is defined by means of a d.c. magnetization measurement test. In the test, a magentically encodable card is uniformly magnetized with a high or saturated d.c. field, for example, at 11 kilooersted, with the field parallel to the length of the card. The card then is passed through a card reader and the resultant signal analyzed. If magnetic particles are present in large, non-uniform, aggregates, the aggregates act as a large local magnetic dipole and when the card is passed through a card reader, the higher flux changes attributable to the aggregates causes a higher RMS (root mean square) signal. Conversely for small, well-dispersed and distributed particles, the local flux changes are much smaller and when such a card is passed through a card reader, the signal is much smaller and less variable resulting in a small RMS signal. When tested in this way, cards that have the magenetic particles uniformly distributed throughout have a RMS voltage above the system noise level, i.e., above 4 mV RMS, and below 2 OmV RMS.
In accordance with the invention, any suitable ferromagnetic particle may be employed such as, for example, &ggr;-Fe
2
O
3
, Co-&ggr;-Fe
2
O
3
, Co-magnetite; ferromagnetic chromium dioxide, ferromagnetic metal particles, ferromagnetic alloy particles, barium ferrite, strontium ferrite, and the like. It is preferred that the magnetic particles have a coercivity greater than 3,000 Oe, therefore, barium ferrite and strontium ferrite are preferred. It is also preferred that the volume of magnetic particle in the card be less than 0.1 percent and most preferably less than 0.03 percent based upon the volume of the resin employed in making the card. This is preferable because the low density of the magnetic particle allows the achievement of a neutral reflection density of the card, thereby permitting indicia, images, polygrams, and the like on the card without having the interference of color from the presence of the magnetic particles. The loading of the magnetic particles into the resin from which the card is formed in these small percentages gives a low remanant field and thus prevents the card made in accordance with this invention from operating as a master media card which would readily permit the counterfeiting of lower coercivity cards because of the high coercivity of the material employed.
The ferromagnetic particles are dispersed in an organic fluid medium which when combined with a thermoplastic resin serves to plasticize the resin. Any suitable organic fluid medium having this characteristic may be employed in the method in accordance with this invention such as, for example, phosphate esters such as tricresyl phosphate; glycol esters, such as diethylene glycol mixed esters; phthalate esters such as dibutyl phthalate, dipropyl phthalate, dioctyl phthalate, and the like; alkyl stearates such as hexyl stearate, and butyl stearate; tetraethylene glycol dimethyl ether, ethyl acetate copolymers, lactams, lower alkyl esters of ethylene bis-glycolic acid, ether esters, or diesters of an alkylene glycol or a polyalkylene glycol, polyacrylic acid esters, polyvinyl acetate, and the like. The phthalate esters, particularly dibutyl phthalate is preferred. The plasticizer serves not only to provide for a uniform dispersion of the ferromagnetic particles in the organic fluid medium, but also enhances the flexibility of the card, thereby reducing embrittlement.
In the preparation of the dispersion of ferromagnetic particles in the organic fluid medium, it is preferred that a dispersing agent be included. Suitable dispersing agents include fatty acid amines, and commercially available wetting agents such as Witco Emcol CC59 which is a quaternary amine available from Witco Chemical Corp. Rhodafac PE 510, Rhodafac RE 610, Rhodafac RE 960, and Rhodafac LO 529 which are phosphoric acid esters available from Rhone-Poulenc. Further, the dispersing agent as set forth in U.S. Pat. No. 5,395,743 which is sold by Zeneca Inc. under the trade designation Solsperse 24000 is preferred. Mixtures of the above-mentioned dispersing agents can also be employed.
After the dispersion of the ferromagnetic particles in the organic fluid medium is formed, a composite is next prepared by mixing the dispersion with a thermoplastic resin. Any suitable thermoplastic resin may be employed such as, for example, polystyrene, polyamides, homo and copolymers of vinylchloride, polycarbonates, homo and copolymers of polyolefins, such as polyethylene, polypropylene, copolymers of ethylene and propylene; polyesters such as those prepared from dibasic carboxylic acids and divalent alcohols including succinic acid, dipic acid, phthalic acid, terephthalic acid, naphthalene dicarboxylic acid, and the lower alkyl esters thereof, and suitable glycols such as, for example, ethylene glycol, propylene glycol, butylene glyc
Condo Mary-Irene Elizabeth
James Robert Owen
Rowley Lawrence Allen
West Bradford Drake
Eastman Kodak Company
Silbaugh Jan H.
Wells Doreen M.
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