CA1246869A - Nonmagnetic thermal transfer ribbon - Google Patents

Abstract

NONMAGNETIC THERMAL TRANSFER RIBBON

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

Description

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NONMAGNET C THERMAL TRANSFER RIBBON

Background of the Invention In the printing field, the impact type printer has been the predominant apparatus for providing increased throughput 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 ele~ents are caused to be driven against a ribbon and paper or like record media adjacent 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 arrangement includes the use of carbonless paper wherein the impact from a print wire or a type element causes rupture of encapsulated material for marking the paper. Al~o known are printing inks which contain magnetic particles wherein certain of the particles are transfered to the record media for encoding characters in manner and fashion so as to be machine readable in a subsequent operation. One of the known encoding systems is MICR (Magnetic Ink Character Recognition) utili~ing the manner of operation as just mentioned.
While the impact printing method has dominated the industry, one disadvantage of this type printing is the noise level which is attained 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 requirements for heating of extremely precise areas of the record ~2~
- ? -media by use of relatively high currents. The intenseheating of the localiæed areas causes transfer of ink from a ribbon onto the paper or alternatively, the paper may be of the thermal type which incl~des materials that are responsive to the generated heat.
RepresentativQ documentation in the area of nonimpact printing includes United States Patent No~
3,117,018, issued to E. Strauss on January 7, 1964, which discloses a color transfer medium and method of producing the same by applying a coating consisting of a polycarbonatel a solvent, a plasticizer and a pigment, and then drying the coating to form a solid transfer layer.
United States Patent No 3,413,183, issued to Ho T. Findlay et al. on November 26, 1968, discloses a transfer medium provided by a coating process wherein the transfer layer is a polycarbonate having voids which hold an imaging material.
Unitecl 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 resint plasticizer, and a ~ensible dye or oxide pigment material.
Unitecl States Patent No. 3,744,611, issued to L. Montanari et al. on 3uly 10, 1973, discloses an electrothermal 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 and a coating of electrically resistive material on the other surface.
United 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 layer of thermoplastic resin, carbon black, pigment or oleic acid fats, and wax, mineral oils or vegetable oils.

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United 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 providing a substrate/ coatin~ the substrate with an aqueous composition and then drying the coating.
United States Patent No. 4,103,066, issued to G. F. Brooks et al. on July 25, 1978~ discloses a ribbon for nonimpact printing comprising a tran~fer coating and a substrate which is a polycarbonate resin containing a percentage by 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 medium present in a percentage by weight of the total nonvolatile components.
United 5tates Patent No. 4,291,994, issued to T~ L. Smith et al. on September 29, 1981, discloses a ribbon for nonimpact printing which comprises a transfer coating and a substrate containiny resin which is a mixture of polycarbonate, a block copolymer of bisphenol carbonate and dimethyl siloxane, and a percentage by weight of electrically-conductive carbon black.
United States Patent Mo. 4,309,117, issued to I.. S. Chang et al. on January 5, 1982, discloses a ribbon configuration for resistive ribbon thermal transfer printing comprising a low resistive layer of conductive carbon, a high resistive layer of a ceramic metal mixture, a stainless steel conductive layerr and an ink transfer layer.
And, United States Patent No. 4,320,170, issued to H. T. Findlay on March 16, 1982, discloses a ribbon for thermal printing which has a transfer coating and a substrate which is a resin containing carbon black.

- ~ - 62118-1623 Summary of the Invention The present invention relates to nonimpact printing. More particularly, the invention provides a formulation or composition for producing a nonmagnetic thermal ribbon or transfer medium for use in imaging or encoding characters on paper or like record media documents which enables human reading of the imaged or encoded characters. The thermal transfer ribbon enables printing in quiet and efficient manner and makes use of the advantages of thermally printing documents with a signal inducible ink.
In accordance with the present invention, there is provided a thermal transfer ribbon for use in nonimpact pr;nting comprising a capacitor tissue substrate and a thermal transfer layer which is a mixture comprising the combinatin of a wax emulsion essentially containing an amide wax, a hydrocarbon wax, a styrene copolymer resin, a polyethylene, and a dispersion essentially containing a cupric oxide, a carbon black suspended in aliphatic solvent, a petrolatuml and a dispersion of polymeric wax in xylene, all by dry 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 nonmagnetic pigment and a wax mixture dispersed in a binder mix of polyethylene and resin to form the emulsion. The resin and the solids of the wax emulsion are mixed into solution along with a filler and the wax emulsion is added after 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 techniques.

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- 4a - ~2118-1623 In view of the above discussion, the principal object of the present invention is to provide a ribbon including a thermal-responsive coating thereon.
Another object of the present invention i5 to provide a nonmagnetic thermal transfer ribbon including a coating thereon for use in imaging or encoding operations~
An additional object of the present invention is to provide a nonmagnetic 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.

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~ further object of the present invention is to provide a coating on a ribbon substrate, which coating includes a nonmagnetic 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 imaging operation in printing manner at precise positions and during the time when the thermal elements are activated to produce a well-defined and precise or sharp ima~e.
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 nonmagnetic thermal printing.
Additional advantages and features of the present invention will become apparent and fully understood fro~n a reading of the following description taken together with the annexed drawing.

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

Description of the Preferred Embodimen_ The transfer ribbon 20, as illu~trated in Figs~ 1 and 2, comprises a base or substrate 22 of thin smooth tissue-type paper or polyester-type plastic or like material haviny a coating 24 which is ~2~

t~ermally activated ancl includes nonmagnetic pigment or particles 26 as an ingredient therein for use in imaging or encoding operations to enable human or reflectance reading of characters. Each character that is imaged on a receiving paper 28 or like record media produces a uni~ue waveform that is recognized and read by the reader. In th~ case of thermal transfer ribbons relying solely on the nonmagnetic thermal printing concept, the pigment or particles 26 include conventional coloring materials such as pigments, fillers and dyes.
As alluded to above, it is noted that the use of a thermal printer having a print head element, as 30, substantially reduces noise levels in the printing operation and provides reliability in imaging or encoding of paper or like docum~nts 28. The thermal transfer ribbon 20 enables the advantages of thermal printing while encoding or imaging the document 28 with a nonmagnetic signal inducible ink. When the heating elements 30 of a thermal print head are activated, the imaging or encoding operation requires that the pigment or particles of material 26 on the coated ribbon 20 be completely transferred from the ribbon to the document 28 in manner and form to produce precisely defined characters 32 for recognition by the reader. In the case of nonmagnetic thermal printing, the imaging or encoding material 26 is completely transferred to the document 28 to produce precisely defined characters 32 for recognition and human reading thereof.
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 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 6~

appropriate amounts as set forth in the following table of Example I.
EXAMPLE I

___ Wax EmulsionPercent Dry wet Ranae Armid C Wax 37.3 37.3 20-60%
WB-5 Wax 18.5 18.5 15-60%

Polyethylene11.7 11.7 0-29 Piccotex-100 Resin 3205 32.5 0-40%
1 00 ~ O 100 . O
Mineral Spixits _00.0 200.0 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.
me second stage of the process includes preparation of the thermal transfer coating wherein the following ingredients in appropriate amounts, as set forth in Table 2, are placed into dispersion equipment such as a ball mill, a shot mill, a sand mill, or an attritor and ground for a period of approximately 20-40 minutes, or for a sufficient period of time to provide a uniform fine (3-5 microns size) dispersion.

Material Percent Dry Wet Ranqe Wax Emulsion 55.0 110.0 10-99%
(from Table 1 50% solids) Melamine Sulfonamid Resin 6.5 6.5 0-30%

~6~1~9 - ~ ~ 62118-1623 Codispersion 31L62 35.0 66.1 1~60%
(in various aliphatic solvents at 56~ solids) Slip-Ayd 4251.0 5.0 0-10%
(in Xylene at 20~ solids) Soya Lecithin0.5 0.5 0-10%
Morfast Blue2.0 4.0 0-10%
(in N-Propanol at 50~ solids) 100.0 13~.1 Mineral Spirits 58.0 250.1 Example II provides slightly different ingredients and amounts thereof, as set forth in Tables 1 and 2~ for preparing th~ transfer coating or layer.

EXAMPLE II

Wax EmulsionPercent Dry Wet Range Ceramid 39.S 39.5 10-60%
WB-17 39.5 39.5 10-60%
Piccotex-75 9.4 9.4 0-40 AC-617 11.6 11.6 0-40 100.O 100.O
Mineral Spiri.ts 100.0 ~00 . O

30Material Percent Dry Wet Range Wax Emulsion70.0 140.0 10-99%
~from Table 1) Cupric Oxide10.0 10.0 0-30 ~2~6~

Codi~persion 31L62 14.0 25.0 1-60%
Slip-Ayd 4251.0 5.0 0-10%
Petrolatum3.0 3.0 0-10%
Morfast Blue2.0 4.0 0-10%
10~.0 187.0 Mineral Spirits 9B.7 285.7 Example III further provides slightly different ingredients and amounts thereof, as set forth in Tables 1 and 2, for preparing the transfer coating or layer.

EXAMPLE III

Wax EmulxionPercent Dry Wet Range Ceramid 37.5 37.5 10-60%
WB-17 37.5 37.5 10-60%
Piccotex-759,4 9.4 0-40%
AC-430 11.6 11.6 0-40%
V Wax 4.0 4.0 0-15%
100.O 100.O
Mineral Spirits 100.0 200~0 Material Percent Dry Wet Wax Emulsion70.0 140.0 10-99 (from Table 1) Cupric Oxide6.0 6.0 0-30%
Melamine Sulfonamid Resin 1.0 1.0 0-303 - 10 - 6211~1623 Codispersion 31L62 20.0 35.7 1-60%
Slip~Ayd 4251.0 5.0 0-10%
Morfast Blue2.0 4.0 0 10%
100.0 191.7 Mineral Spirits 94.0 285.7 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. V wax is a polyvinyl ether wax. AC-430 is an ethylene vinyl acetate copolymer. AC-617 i9 a low molecular weight polyethylene. Piccotex-75 and Piccotex-100 are hard, color stable, substituted styrene copolymer resins.
Melamine Sulfonamid is an amino resin of high molecular 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 Morfast Blue is an organic solvent system colorant in N-propanol. Soya Lecithin is a wetting agent, oil-like extract of soybean.
Petrolatum is a non-polar, hydrophobic, biologically inert, petroleum derivative.
The nonvolatile materials are controlled at 25-50% for proper viscosity. It should be noted that all ingredients are careEully 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 30-40 gauge capacitor tissue, manufactured by Schweitzer, or 17-35 gauge polyester film as manufactured by duPont under the trademark Mylar, should have a high tensile 36~

~ 62118-1623 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 8 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 lS0 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 20. The above-mentioned coating weight, as applied by the Meyer rod onto a preferred 9-12 microns thick substrate, overall translates to a total thickness of 15-20 microns.
The availability of the various ingredients used in the present invention is provided by the following list of companies.
Material SuPplier Armid C Wax Armak Chemicals Inc.
Ceramid Wax Glyco Chemical V Wax BASF
WB-5 Wax Petrolite Corp.
WB-17 Wax Petrolite Corp.
AC-430 Polyethylene Allied Chemical Corp.
AC-617 Polyethylene Allied Chemical Corp.
Piccotex-75 Resin Hercules Inc.

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- 12 - 62118-~623 Piccote~-100 Resin Hercules Inc.
Mineral Spirits Ashland Chemical Co.
Melamine Sulfonamid Resin DayGlo Codispersion 31L62 Borden Chemical Co.
Slip-Ayd 425 Daniel Products Soya Lecithin Capricorn Chemical Morfast Blue Pylam Products Petrolatum Witco Chemic~l ~upric Oxide American Chemet It is thus seen that herein shown and described is a thermal transfer ribbon for use in thermal printing operations which includes a thermal responsive 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 human 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 (13)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A thermal transfer ribbon for use in nonimpact printing comprising a capacitor tissue substrate and a thermal transfer layer which is a mixture comprising the combination of a wax emulsion essentially containing an amide wax, a hydrocarbon wax, a styrene copolymer resin, a polyethylene, and a dispersion essentially containing a cupric oxide, a carbon black suspended in allphatic solvent, a petrolatum, and a dispersion of polymeric wax in xylene, 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 1 to 60%
codispersion in aliphatic solvents.

3. The ribbon of claim 1 wherein the transfer layer mixture contains about 1 to 10%
polyethylene wax.

4. The ribbon of claim 1 wherein the transfer layer mixture contains about 1 to 10% wetting agent.

5. The ribbon of claim 1 wherein the transfer layer mixture contains the amide wax and the synthetic wax in a ratio of about 2:1.

6. The ribbon of claim 1 wherein the transfer layer mixture contains about 1 to 20%
polyethylene.

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

8. The ribbon of claim 1 wherein the transfer layer consists of a coating weight about 3 to 8 grams per square meter.

9. The ribbon of claim 1 wherein the transfer layer contains about 1 to 10% cupric oxide.

10. The ribbon of claim 1 wherein the thermal transfer layer mixture contains about 1 to 2%
dispersion of polymeric wax in xylene.

11. The ribbon of claim 1 wherein the thermal transfer layer mixture contains about 1 to 2%
organic solvent system colorant in N-propanol.

12. A thermal transfer ribbon for use in nonimpact printing comprising a capacitor tissue substrate and a thermal 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 20% styrene copolymer resin, about 5 to 30% ethylene vinyl acetate copolymer, about 5 to 30% polyvinyl ether wax, and a dispersion essentially containing about 5 to 20%
cupric oxide, about 5 to 35% amino resin, and about 5 to 25% carbon black suspended in aliphatic solvent, all by dry weight, and about 60 to 80% solvent by wet weight for solubilizing the mixture.

13. A method of making a thermal transfer ribbon having a substrate of capacitor tissue and a thermal transfer layer comprising the steps of:
preparing a wax emulsion essentially containing about 30 to 50% amide wax, about 15 to 25%
hydrocarbon wax, and about 5 to 15% polyethylene, mixing the wax emulsion in a dispersion essentially containing about 5 to 15% amino resin, about 10 to 25% carbon black suspended in aliphatic solvents, and about l to 5% wetting agent, solubilizing the mixture of wax emulsion and dispersion in mineral spirits, and applying the solubilized mixture of wax emulsion and dispersion to the capacitor tissue substrate.