CA1241837A - Magnetic thermal transfer ribbon - Google Patents

Abstract

MAGNETIC THERMAL TRANSFER RIBBON

Abstract of the Disclosure A magnetic thermal transfer ribbon includes a substrate, and a coating thereon comprising a mixture of amide wax, polyethylene, petroleum hydrocarbon resin, and iron oxide particles prepared in a two stage process to provide precise and well-defined, magnetically readable characters.

Description

MAGNETIC T~RMAL TRA~SFlE:R_RIBBON

Back~round of the Inv tion In the printing fieldr the impact type printer has been the predominant apparatus for provid-ing increased thr~ughput of printed information. The impact printers have included the dot matrix type wherein individual print wires are driven from a home position to a printing position by individual and separate drivers, and the full character type wherein individual type elements are caused to be driven ayainst a ribbon and paper or like record media adja-cent and in contact with a platen.
The typical and well-known arrangement in a printing operation provides for transfer of a portion of the ink from the ribbon to result in a mark or image on the paper. Another arranqement includes the use of carbonless paper wherein the impact from a print wire or a type element causes rupture of encap-sulated material fvr marking the paper. Also known are printing inks which contain magnetic particles whPrein certain of the particles are transferred to the record media for encoding characters in manner and fashion so as to be machine readable in a subsequent operationO One of the known encoding systems is ~ICR
(Magnetic Ink Character Recognition) utilizing the manner of operation as just mentioned.
While the irnpact printing method has dominated the industry, one disadvantage of this type printing is the noise level which is atkained during printing operation. Many efforts have been made to reduce the high noise levels by use of sound absorbing or cushioning materials or by isolating the printing apparatus. More recently, the advent of thermal printing which effectively and significantly reduces the noise levels has brought about the requirement for heating of extremely precise areas of the record media 3~' by use o relatively high currents. The intense heating of the localized areas causes transer of ink from a ribbon onto the paper or alternatively, the paper may be of the thermal type which includes mate-rials that are responsive to the generated heat.
Further~ it is seen that the use of thermal printing is adaptable for MICR encoding of documents wherein magnetic particles are caused to be trans-ferred onto the documents for machine reading of the characters. The thermal transfer printing approach for use in MICR encoding of documents enables relia-bility in operation at the lower noise levels, Representative documentation in the area of magnetic ink for use in nonimpact printing includes United States Patent No. 3,042,616, issued to R~ J.
Brown on July 3, 1962, which discloses a process of preparing magnetic ink by wetting powdered iron with a resinous solution and adding an aqueous slurry of carbonate to form droplets surrounded by solvent liquidO The solven~ is separated by water and the particles are then filtered and dried to produce spheres of magnetic ink.
United States Patent No. 3,117,018, issued to E~ Strauss on January 7, 1964, discloses a color transfer medium and method of producing the same by applying a coating consisting of a polycarbonate, a solvent, a plastisizer and a pigment, and then drying the coating to form a solid transfer layer.
United States Patent No. 3,284,360, issued to J. V. Peshin on November 8, 1966, discloses a transfer coating of magnetic pigment in a solution of a stearamide binder or mixtures of stearamide and oleamide and a solvent binder. A preferred solution includes a major proportion o magnetic pigment and a minor proportion of the binder consisting primarily of stearamide or mixtures of stearamide and oleamide.

13 ~

United States Patent No. 3,413,183, issued to H. T. Findlay et al. on November 26, 1968, cliscloses a transfer medium provided by a coating process wherein the trans~er layer is a polycarbonate having voicls which hold an imaging materialO
United States Patent No~ 3,4g6,015, issued to D. A. Newman et al. on February 17, 1970, discloses pressure-sensitive magnetic transfer elements for placement of magnetically-sensible images under vari-ous conditions of u~e. The imaging layer has a porous resinous binder containing pressure-exudable liquid ink. The ink comprises a liquid oil vehicle and magnetic pigment having an oil absorption value below twenty (20) and a tape density value above twenty t20).
United States Patent No. 3,663,278, issued to J. H. Blose et al. on May 16, 1972, discloses a thermal transfer medium having a coating composition of cellulosic polymer, thermoplastic resin, plastic~
izer and a sensible dye or oxide pigment material.
United States Patent No. 3~744,611, issued to L. Montanari et al. on July 10, 1973, discloses an electro~hermal printer for nonimpact printing on plain paper that uses a ribbon made of a substrate having a thermal transferable ink coated on one surface thereof ancl a coating of electrically resistive material on the other surface.
Unitecl States Patent No. 3,855,448, issued to T. Hanagata et al~ on December 17, 1974, discloses a print ribbon comprising a heat-resistant support sheet with a heat-fusible material la~er of thermoplastic resin, carbon black, pigment or oleic acid fats, ancl wax, mineral oils or vegetable Oilsa ~ nited States Patent No. 4,022,936, issued to R. E. Miller et al. on May 10~ 1977, discloses a process for making a sensitized record sheet by pro-viding a substrate, coating the substrate with an aqueous compositionv and then drying the coating~

United States Patent No. 4,103~066, issued to G. F. Brooks et alO on July 25, 1978~ discloses a ribbon for nonimpact printing comprising a transfer coating and a substrate which is a polycarbonate resin containing a percentage b~ weight of electrically-conductive carbon black.
United States Patent No. 4,251,276, issued to W. I. Ferree et al. on February 17, 1981, discloses a transfer ribbon having a substrate coated with a thermally-activated ink composition comprising a thermally-stable polymer, an oil-gelling agent, and an oil-dissolving medi~ present in a percentage by weight of the total nonvolatile components.
United States Patent No. 4,291,g94~ issued to T. L. Smith et al. on September 29, 1981, discloses a ribbon for nonimpact printing which comprises a trans-fer coating and a substrate containing resin which is a mixture of polycarbonate~ a block copolymer of bisphenol carbonate and dimethyl siloxane7 and a percenta~e b~ weight of electrically-conductive carbon black.
United States Patent Mo. 4,309,117~ issued to L. SO Chang et alO on January 5, 1982, discloses a ribbon configuration for resistive ribbon thermal transfer printing comprising a low resistive layer of conductive car~on, a high resistive layer of a ceramic metal mixture, a stainless steel conductive layer~ and an ink transfer layer.
United States Patent No. 4,315,643, issued to Y. Tokunaga et al. on February 16, 1982, discloses a heat sensitive transfer element having a foundation, a color developln~ layer on one surface and a hot melt ink layer on the other surface of the foundation. The ink layer has a heat conductiny material and a solid wax.
Unlted States Patent No 4,3~0,170, issued to . T~ Findlay on March 16, 1982, discloses a ribbon 3~

for thermal printing which has a transfer coating and a substrate which is a resin containing carbon black.
And~ United States Patent No. 4,463,0334, issued to Y. Tokunaga et al. on July 31~ 19~, discloses a heat-sensitive magnetic transfer element for printing a magnetic image to be recognized by a magnetic ink character reader (MICR) and which element comprises a heat-resisting foundation and a heat-sensitive transferring layer including a ferromagnetic substance powder in a wax and/or plastic binder, and having a melting point of 50 degrees to 120 degrees C
so that portions of the layer can be transferred onto a receiving paper in the form of a magnetic image by a thermal printer.

Summary of the Invention The present invention relates to nonimpact printing. More particularly, the invention provides a formulation or composition for producing a thermal magnetic ribbon or transfer medium for use in imaging or encoding characters on paper or like record media documents which enables machine reading of the imaged or encoded characters. The thermal magnetic transfer ribbon enables printing in quiet and efficient manner and makes use of the advantages of thermal printing while encoding documents with a magnetic signal inducible ink.
In accordance with the present invention, there is provided a magnetic thermal ribbon for use in nonimpact printing comprising a substrate and a transfer layer which is a mixture comprising the combination of a wax emulsion essentially containing about 25 to 50% amide wax, about 25 to 50% hydrocarbon wax, about 5 to 20~ polyethylene, about 5 to 20%
styrene copolymer resin, and a dispersion essentially containing about 25 to 60% magnetic pigment, about 1 to 5% wetting agent, and about 1 to ~% dye, all by dry - 5~ -weight, and about 60 to 80% solvent by wet weight for solubilizing the mixture.
The ribbon comprises a thin, smooth substrate such as tissue-type paper or polyester-type plastic on which is applied a coating that generally includes a magnetic pigment and a wax mixture dispersed in a binder mix of polyethylene and resin to form the emu]sion. The resin and the solids of the wax emulsion are mixed into solution alony with a magnetic filler and the wax emulsion is added aEter wetting the pigment. The coating is put through a setting procedure by drying the coating at an elevated temperature /

and the coating is then applied to the substrate by well-known or conventional coating techniquesu In view of the above discussion~ the principal object of the present invention is to pro-vide a ribbon including a thermal magnetic coating thereon.
Another object of the present invention is to provide a thermal magnetic transfer ribbon including a coating thereon for use in encoding operations.
An additional object of the present invention is to provide a maynetic coating on a ribbon having ingredients in the coating which are responsive to heat for transferring a portion of the coating to paper or like record media.
A further object of the present invention is to provide a coating on a ribbon substrate, which coating includes a magnetic pigment and a wax emulsion dispersed in a binder mix and which is responsive to heat for transferring the coating in precise printing manner to paper or like record media~
Still another object of the present invention is to provide a thermally-activated coating on a ribbon that is completely transferred from the base of the ribbon onto the paper or document in an encoding operation in printing manner at precise positions and during the time when the thermal elements are activat-ed to produce a well-def ined and precise or sharp image.
Still a further object of the present invention is to provide a two stage process which includes the preparation of a specific wax emulsion and the preparation of a transfer coating for use in magnetic thermal printing~
Additional advantages and features of the present invention will become apparent and ully understood from a readin~ of the following description taken together with the annexed drawing.

3~

Brief Description of the Drawing Fig. 1 illustrates a thermal element operating with a ribbon base having a transfer coating thereon incorporating the ingredients as disclose~ in the present invention; and Fig. 2 shows the receiving paper with a coating particle transferred thereto.

Description of the Preferred Embodiment m e transfer ribbon 20, as illustrated in Figs. 1 and 2, comprises a base or substrate 22 of thin~ smooth tissue-type paper or polyester-type plastic or like material having a coating 24 which is thermally activated ancl includes magnetic particles 26 as an ingredient therein for use in encoding opera-tions to anable machine reading of characters. Each character that is imaged on a recei~ing paper 28 or like record media produces a unique magnetic waveform that is recognized and re~d by the reader.
As alluded to abovey it is noted that the use of a thermal printer having a print head element, as 30, substantially reduces noise levels in the printiny operation and provides reliability in MICR encoding of paper or like documents 28. The thermal magnetic transfer ribbon 20 enables the advantages of thermal printing while encoding the document 28 with a magnet-ic signal inducible ink. When the heating elements 30 of a thermal print head are activated, the encoding operation requires that a portion of the magnetic particles or like material 26 on the coated ribbon 20 be completely transferred from the ribbon to the document ~8 in manner and form to produce precisely defined characters 32 for recognition by the reader.
The thermal transfer ribbon of the present invention is produced in a two stage process wherein the first stage includes preparation of a specific wax 3~7 :
emulsion or formulation and the second stage includes preparation of the transfer coating or layer.
A preferred wax emulsion or formulation to satisfy the first stage includes the ingredients in appropriate amounts as set forth in the follo~7ing table of Example I.

EXA~PLE I
TAB LE: 1 Wax_EmulsionPercent Dr~ Wet Ranqe Ceramid*Wax39.5 39.5 20-60%
WB-5 h'ax 39.5 39.5 20-60%

Polyethylene 11.7 11.7 0-20%
Piccotex*100 Resin 9.3 9.3 0-20%
100.0 100.0 Mineral Spirits 100.0 200.0 The nonvolatile materials in the above formulation equate to 50%, and it is here noted that Lacolene, or VM and P Naptha, can be substituted in place of the mineral spirits.
The second stage of the process includes preparation of the magnetic thermal transfer coating wherein the followinq ingredients in appropriate amounts, as set forth in Table 2 of Example I, are placed into dispersion e~uipment such as a ball mill, a shot mill, a sand mill, or an attritor and qround for a period of approximately 20-40 minutes, or for a sufficient period of time to provide a uniform fine (3 to 5 microns size) dispersion, : * Trade mark Material Percent Dry Wet Range Iron Oxide 37.4 37.4 1-30%
Wax Emulsion 50.5 101.0 10-99%
tfrom Table 1 50% solids) Melamine Sulfonamid . Resin 6,1 6.1 0-20%
Codispersion 31L62 1.0 1.7 0-40%
(in various aliphatic solvents at 56% solids) : Slip-Ayd*425 1.0 5.0 0-10%
(in Xylene at : 20% solids) Soya Lecithin 1.0 1.0 0-10%
Flexo*Black X12 3.0 6.1 0-10%
(in N-Propanol at 50~ solids) :~' 100.0 158.3 Mineral Spirits 79.7 ~ 238.0 ':' Example II provides slightly different ingredients and amounts thereof, as set forth in Tables 1 and 2, for preparation of the transfer coating or layer.
:
'.
~ * Trade mark '~

~2~3~

EXAMPLE II

Wax Emulsion Percent Dry Wet Range Armid C 39.5 39O5 20-60 WB-5 39.5 39.5 20-60%
AC-617 11~7 11.7 0-2Q~
Piccotex-75 9.3 9.3 0-20%
100.O 100.O
Mineral Spirits 100.0 200.0 Material Percent Dry Wet Range Iron Oxide 37.4 37.4 1-80%
Wax Emulsion 50.5 101.0 10-99%
(from Table 1) Melamine Sulfonamid Resin 6.1 6.1 0-20%
Codispersion 31L62 1.0 1.7 0-40%
Slip-Ayd 425 1,0 5.0 0-10%
Soya Lecithin 1.0 1.0 0-10%
Flexo Black X12 3.0 5.1 0-10%
100.0 15~.3 Mineral Spirits 79.7 238.0 A polyterpene, such as Wingtack 95, may be substituted for the Piccotex 75 in Table 1.
Example III further provides slightly different ingredients and amounts thereof, as set Eorth in Tables 1 and 2, for preparation of the transfer coating or layer.

EXAMPLE III
TABLÆ 1 Wax EmulsionPercent Dry Wet Range Ceramid* 39.5 39.5 20-60%
WB-17 39.5 39.5 20-60%
AC-430 9.7 9.7 0-20%
~C-617 2.0 2.0 0-20%
Piccotex-100 9.3 9.3 0-20%
100.O 100.O
Mineral Spirits 100.0 200.0 Material Percent Dry Wet Range Iron Oxide 30.4 30.4 1-80%
Wax Emulsion 50.5 101.0 10-99%
(from Table 1) Melamine Sulfonamid Resin 6.1 6.1 0-20%
Cupric Oxide 7O0 7O0 0-40%
Codispersion 31L62 1.0 1.7 0-40%
Slip-Ayd 425 1.0 5.0 0-10%
Soya Lecithin 1.0 1.0 0-10%
Flexo Black X123.0 6.1 0-10%
100.0 158.3 Mineral Spirits 79.7 238.0 Armid C is a fatty acid derived-multi carbon chain lengths amide wax and Ceramid is a fatty acid derived amide wax. WB-5 and WB-17 are oxidized, isocyanated hydrocarbon waxes. AC-430 is an ethylene vinyl acetate copolymer. AC-617 and AC-1702 are low molecular weight polyethylenes. Piccotex-75 and Piccotex-100 are hard, color stable, substituted * Trade mark styrene copolymer resins. Melamine Sulfonamid is an amino resin of high moleculor weight made from melamine and formaldehyde. Codispersion 31L62 is a colloidal dispersion of carbon black suspended in an aliphatic solvent. Slip-Ayd 425 is a 20% dispersion of high melting point polymeric wax in xylene. Soya Lecithin is a wetting agent, oil-like extract of soybean. Flexo Black X12 is a 50% nigrosine dispersion in alcohol. Wingtack 95 is a polyterpene resin.
The nonvolatile materials are controlled at 25-50~ for proper viscosity. It should be noted that all ingredients are carefully weighed and solubilized in the mineral spirits using appropriate heat and agitation. After the solution is complete, it is slowly cooled to form a viscous wax dispersion to prepare a thermally active, transfer coating.
The substrate or base 22, which may be 35-40 gauge capacitor tissue, manufactured by Schweitzer, or 25-35 gauge polyester film as manufactured by duPont under the trademark Mylar, should have a high tensile strength to provide for ease in handling and coating of the substrate. Additionally, the substrate should have properties of minimum thickness and low heat resistance to prolong the life of the heating elements 30 of the thermal print head by reason of reduced print head actuating voltage and the resultant reduction in burn time.
The coating 24 is applied to the substrate 22 by means of conventional coating techniques such as a Meyer rod or like wire-wound doctor bar set up on a typical solvent coating machine to provide the coating weight of between 3 and 13 grams per square meter.
The coating is made up of approximately 25-50%
nonvolatile material and may be maintained at a desired temperature and viscosity throughout the coating process. After the coating is applied to the substrate, the web of ribbon is passed through a dryer at an elevated temperature in the range between 93 and 150 degrees C for approximately 5-10 seconds to ensure good drying and adherence of the coating 24 onto the substrate 22 in making the transfer ribbon ~0. The above-mentioned coating weight, as applied by the Meyer rod onto a preferred 9-12 microns thick capacitor grade tissue, translate to an overall total thickness of 15-25 microns.
The availability of the various ingredients used in the present invention is provided by the follo~ing list of companies.
Material Supplier Ceramid Wax Glyco Chemicals Inc.
Armid C Wax Armak Chemical WB-5 Wax Petrolite Corp.
WB-17 Wax Petrolite Corp.
AC-430 Polyethylene Allied Chemical Corp.
AC-617 Polyethylene Allied Chemical CorpO
AC-1702 Polyethylene Allied Chemical Corp.
Piccotex 75 Resin Hercules Inc.
Piccotex-100 Resin Hercules Inc.
Mineral Spirits Ashland Chemical Co.
Iron Oxide BASF 345 Cupric Oxide American Chemet Melamine Sulfonamid Resin DayGlo Codispersion 31L62 Borden Chemical Co.
Slip-Ayd ~25 Daniel Products Soya Lecithin Capricorn Chemical Flexo Black X12 BASF
Wingtack 95 Goodyear Chemical Ceramid is a trademark of Glyco Chemicals Inc. and Armid is a trademark of Armour Chemical. A-C
is a trademark of Allied Chemical. Piccotex is a trademark of Pennsylvania Industrial. Codispersion is a trademark of Binney and Smith. Slip-Ayd is a trademark of Daniel Products. And, Wing-Tack is a trademark of Goodyear.
It is thus seen that herein shown and described is a magnetic thermal transfer ribbon for use in thermal printing operations which includes a thermal responsive magnetic coating on one surface thereof. The coated ribbon enables transfer of coating material onto documents or like record media during the printing operation to form characters thereon in an imaging or in an encoding nature, permitting machine reading of the characters. The present invention enables the accomplishment of the objects and advantages mentioned above, and while a preferred embodiment has been disclosed herein, variations thereof may occur to those skilled in the art. It is contemplated that all such variations and modifications not departing from the spirit and scope of the invention hereof are to be construed in accordance with the following claims.

Claims (10)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A magnetic thermal ribbon for use in nonimpact printing comprising a substrate and a transfer layer which is a mixture comprising the combination of a wax emulsion essentially containing about 25 to 50% amide wax, about 25 to 50% hydrocarbon wax, about 5 to 20% polyethylene, about 5 to 20%
styrene copolymer resin, and a dispersion essentially containing about 25 to 60% magnetic pigment, about 1 to 5% wetting agent, and about 1 to 4% dye, all by dry weight, and about 60 to 80% solvent by wet weight for solubilizing the mixture.

2. The ribbon of claim 1 wherein the transfer layer mixture contains about equal amounts of amide wax and hydrocarbon wax.

3. The ribbon of claim 1 wherein the transfer layer consists of a coating weight about 3 to 13 grams per square meter.

4. The ribbon of claim 1 wherein the transfer layer contains about 5 to 20% cupric oxide.

5. The ribbon of claim 1 wherein the mixture consists of ingredients ground to about 3 to 5 microns.

6. The ribbon of claim 1 wherein the mixture contains about 5 to 20% high molecular weight amino resin made from melamine and formaldehyde.

7. The ribbon of claim 1 wherein the mixture contains about 5 to 20% disperson of carbon suspended in aliphatic solvent.

8. The ribbon of claim 1 wherein the mixture contains about 1 to 5% dispersion of polymeric wax in xylene.

9. A magnetic thermal ribbon for use in nonimpact printing comprising a substrate and a transfer layer which is a mixture comprising the combination of a wax emulsion essentially containing about 25 to 50% fatty acid derived amide wax, about 25 to 50% oxidized, isocyanated hydrocarbon wax, about 5 to 15% ethylene vinyl acetate copoloymer, about 5 to 15% low molecular weight polyethylene, about 5 to 15%
styrene copolymer resin, and a disperson essentially containing about 25 to 60% iron oxide, about 1 to 5%
wetting agent, and about 1 to 4% nigrosine dye, all by dry weight, and about 60 to 80% solvent by wet weight for solubilizing the mixture.

10. A method of making a magnetic thermal ribbon having a substrate and a thermal transfer layer comprising the steps of:
preparing a wax emulsion essentially containing about 30 to 50% amide wax, about 30 to 50%
hydrocarbon wax, about 5 to 15% polyethylene, and about 3 to 12% styrene copolymer resin, mixing the wax emulsion in a dispersion essentially containing about 25 to 60% magnetic pigment, about 1 to 5% wetting agent, and about 1 to 4% dye, solubilizing the mixture of wax emulsion and dispersion in mineral spirits; and applying the solubilized mixture of wax emulsion and dispersion to the substrate.