US3194676A

US3194676A - Pressure sensitive transfer element

Info

Publication number: US3194676A
Authority: US
Inventors: Krumbein Edgar; Muschter Sigo
Original assignee: Columbia Ribbon and Carbon Manufacturing Co Inc
Current assignee: Columbia Ribbon and Carbon Manufacturing Co Inc; International Business Machines Corp
Priority date: 1960-12-14
Filing date: 1961-12-06
Publication date: 1965-07-13
Anticipated expiration: 1982-07-13
Also published as: DE1186084B; CH427490A; GB1014683A; NL272473A

Description

July 13, 1965 E. KRUMBEIN ETAL 3,194,676

' PRESSURE SENSITIVE TRANSFER ELEMENT Filed Dec. 6, 1961 United States Patent O 3,194,676 PRESSURE SENSHTIVE TRANSFER ELEMENT Edgar Krumbein and Sigo Musehter, Hannover, Germany, assignors to Columbia Ribbon and Carbon Manufacturing Co., Inc., Glen Cove, NX.

' Filed Dec. 6, 1961, Ser. No. 157,453 v Claims priority, application Germany, Dec. 14, 1960, W 29,084; Mar. 16, 1961, W 29,659

Claims. (Cl. 117-361) This invention relatesto` carbon and duplicating paper having a colour-spendinglayer based on a synthetic plastic binder material, and more particularly to the utilization of a combination of. incompatible or substantially incompatible synthetic plasticvbinder materials forvmaking the coating substance for such carbon and duplicating papers.

One yof the most essential requirements imposed on a carbon paper the preparation of which is based on wax,

as well as on synthetic materials consists in that the carbon paper should rather remain plane, and not curlwhen stored or during use. The carbon paper must be insensitive to possible variations of extraneous climatic conditions such as the iniiuence of the temperature and atmospheric humidity.

Although there were not wanting proposals directed to. the solution of this difficult problem, none of the efforts to neutralize the-tendency toward rolling or curling by applying a wax or a synthetic resin on the .back of the carbon paper have up to now led to a satisfactory result.

The presentinvention solves the problem by providing` a novel ink-releasing coating on the front-side of the carbon paper foundation rather than by treating the back of the carbon paper foundation.v

Ink-releasing layers are known which are based upon individual resinous binder materials such as vinyl chloridevinyl acetate-copolymers, or mixtures of resinousbinder materials used in a ratio such they they remain compatible with eachother. The compatibility of resinousmaterials` withone another is a conventionally recognized property whereby the-resinsk have the ability of producing optically clear solid solutions .after they have been dissolved to gether in a mutual solvent and after the solvent has been evaporated. l the resinous materials are incompatible or are used in such a ratio that their compatibility is exceeded, then at least a portion of the-resin separates from the remainder and forms a blush or smoky appearance and loss of optical clarity in the final solid solution.

The present invention relates to the discovery that the tendency of carbon papers to curl or roll may be unexpectedly'overcome by using as the binder material a mixture of synthetic resins which are at least partially incompatible with each other. The microscopic examination of the mixture invisible by an unaided eye as far asfits structure is concerned shows that after the evaporation ofthe solvent the lsynthetic materials within thecolourspending layer have a superiine heterogeneousv alveolar structure. The writing or printing colour matter is stored within said honeycomb-like structure and is delivered'during the writingv procedure in proportioned quantities so that the representation of the lettering is absolutely uniform.

According to the invention, in addition to the heteroi geneity between the hlm-forming material (the synthetic material) and the colour matter proper existing in all known carbon papers based onY synthetic materials, the present ink-releasing layers also' have 'a' Very essential heterogeneity between the incompatible synthetic materials jointly used as film-forming binder materials.

In this connection it has surprisingly beeny discovered that a carbon and duplicating paper the colour-spending materials and which in the finished state has a'micro? 3,i94,676 Patented July V13, 1965 porous alveolar structure does not tend 'toward rolling. Such a carbon paper does not require any additional means for preventing itfrom rolling,-therebyavoiding disagreeable electrostatic charge is either eliminated or at leastreduced by far.. v

According to another embodiment of this invention carbon papers are provided for use in modern registering processes byincluding therein magnetic pigment as the coloring matter. Itis known by present experience that it was impossible to squeeze the magnetic pigments the average size of the particles of which is about 05p. out of the known microporous layers of synthetic materials. While heavy magnetizable ferric oxides arel sufiiierntly tine as individual particles, when in solvents they tend toward coagulation and thus cannot be maintained suiiciently movable in the communicating micropor'es of the usual layers of synthetic material. Contrary, thereto, the utilization of incompatible film-forming binder-materials according to the present invention leads to the lelimination of the coagulation and thus to an intense lettering `which hassuflicient marginal sharpness and a sul'lcient quan-f tity of magnetizable particles.

A few examples with respectto the preparationof the hlm-forming material accordingv to the present invention are set forth hereunder.

Example I It has been found that an emulsion of equal parts ofa 20%A solution of a vinyl chloride-vinyl acetate copolymer and a 20% solution of `a polystyrene is quite advantageous.

1.1 parts ofretlexn blue colour, 4.5 p arts` of gas black, i l 1.9 parts of Milori blue colour, y i 0.2 part of disperser Z,

13.1 parts of castor oil,

5.6 parts of mineral oil,

Y 0.4 part of preservative are pulverivzed in a three roller mill andintermixed within a stirring apparatus with l Y 36.7 partsrof a 20 percent vinyl chloride-vinyl acetatei weights ofthe utilized nonlmixable synthetic'materials to layer of which is prepared of such incompatible'synthetic the ratio 1:1, the greater theelectric neutrality of thev layer. r'Hence it /followsthat inthe above example,V the optimum has been achieved, 7

` Example 2 By adding small-parts only, ofy nitrocelluloseor Vcollodion cotton, respectively, to-vinyl copolymers, the writving properties of `the thus obtained paper will not be impaired. y f' yThe already described -elfect takes place also in this case.

4.8 parts of gas black,

2.2 parts of Milori blue colour, 0.2 parts of disperser Z,

18.8 parts of castor oil, and 0.4 part of preservative are pulverized in a three roller mill and intermixed in a turbulent stirrer With Y 517.6 parts of a 20 percent vinyl chloride-vinyl acetatecopolymer solution (Vino flex) and 22.0 parts of a 15 percent .solution of medium viscous collodion cotton in a mixture of 95% 0f butanone and of methanol,

whereupon the raw paper is coated with this mixture in a manner known per se.

Example 3 Only .at most of the entire content of the synthetic material may consist of cellulose ether, to be utilized with vinyl copolymers.

4.6 parts of gas black, 2.1 parts of Milori blue colour, 0.2 part of disperser Z,

18.4 parts of castor oil `and 0.4 part of preservative are pulverized and intermixed inthe manner shown hereinabove with 60.5 parts of a percent vinyl chloride-vinylY acetatecopolymer solution (Vinollex) and 13.8 parts of an ll percentsolution of medium viscous ethyl cellulose in methyl ethyl ketone,

whereupon the raw paper is coated therewith in a manner known perse.

Example 4 The butadiene-styrene copolymers -are incompatable With vinyl ester copolymers in any ratio. In this case, too, thealready mentioned effect is quite pronounced.

3.6 parts of gas black,

1.7 parts of Milori blue colour, 0.2 part of disperser Z,

14.2 parts of castor oil and 0.5 part of preservative are pulverized in a three roller mill and intermixed in a turbulent stirrer with 40.0 parts of a 20 percent vinyl chloride-vinyl acetatecopolymer solution (Vinoflex) and 40.0 parts of a 20 percent solution of a copolymer of butadiene and styrene in methyl ethyl ketone.

The examples following hereunderV relate to -the preparation of a colour component containing magnetic pigments.

Example 5 The colour component-consists of 12 parts magnetic ypigments S 1l (the trade name of the Farbenfabriken a vinyl chloride-vinyl acetate copolymer in methyl-ethyl trade name of Farbenfabriken Bayer, leverkusen).

ketone and 38 parts of a 20% polystyrene solution in methyl-ethyl-ketone) to a permanent dispersion, Whereupon the mixture is applied to a carrier material in a manner known per se. Y

The dehydrated castor oilin connection with a mineral oil can be yreplaced by blown castor oil `as a vehicle.

Example 6 The `colour component for a carbon paper based on synthetic materials according to the present invention canalso consist of amixture of for example a PV-true blue B (BASF) andthe magnetic pigment S 1l (the In this case, Y3.5 parts of the PV-true blue. (BASF) together with 5 parts of castor oil, 4 parts of dehydratized castor oil and 3 parts `of mineral oils (crystal oil) are pulverized at three intervals in a three-rollermill first, whereupon the space betweenV the rollers is increased to 0.03 mm. and the aforesaid mixture intimately mixed on the roller with 5 parts of the magnetic pigment S ll. The thus obtained pigment paste in stirred inthe turbulent stirrer together with 40 parts of a solution of the synthetic material according to the invention, namely a 20% solution of a vinyl chloride-vinyl acetate copolymer ('Vinoflex) in methyl ethyl ketone and 39.5 parts of a 20% polystyrene solution in methyl ethyl ketone to a permanent dispersion.

A llexible foundation is coated with this mixture in a manner known per se.

A sectional view of the carbon paper according to the present invention in an enlarged scale is shown by way of example in the accompanying drawing;

The ink-releasing layer 2 ,consisting of a part 3 of synthetic binder material'and of a part 4v of synthetic binder material is applied to a flexible foundation l which may be either a paper sheet or another foil. The part 3 of synthetic material is a non-coherent component of fine particles between which there remains a free more or less large intermediate space. The intermediate spaces are filled with the part of synthetic material of the other component of synthetic material which forms a closed phase and thus produces the desired layer formation. Both components Vcontain capillary channels or pores 5 Which are filled with the ink composition of the carbon paper. During the working procedure-that is, during writing, the ink composition of the carbon paper isv squeezed out from the channels or pores 5.

What is claimed is: .Y

1. A pressure-sensitive transfer element comprising a flexible foundation having thereon a microporous inkreleasing layer comprising as the solid binder material a mixture of synthetic plastic materials which are incompatible Yin that they are incapable of forming an optically clear solid solutionafter being dissolved together in a mutual solvent and after the solvent has been evaporated, said binder material having dispersed therein a pressurereleas'able ink comprising oil and coloring matter, the said "mixture of incompatible synthetic plastic materials comprising lat least about 50% by weight of a vinyl resin .together with a sulicient incompatible amount by weight of a synthetic plastic materialV whereby the tendency of the ink-releasing-layer to Vcause the transfer element to curl and roll is substantially completely avoided.

2. A-transfer element yaccording togclaim 1 `VinV which the mixture 'of synthetic plastic binder materials comprises a vinyl chloride-vinyl acetate copolymer and polystyrene in a ratio 0fabout1:l. 5

3. A transfer element `according to claim l in which the mixture of synthetic plastic binder materials comprises a vinyl chloride-vinyl acetate Lcopolymer and `a'butadiene copolymer. j j n v4. A transfer Velement according tol claim 1 in which the mixture of synthetic plastic'binder materials comprises a -vinyl chloride-vinyl acetate copolymer and a cellulose` ester plastic. l

5. A transfer element `according to claim 1 in which the synthetic plastic binder materials are present in a ratio of about 1:1.

6. A transfer element according to claim 1 in which the coloring matter comprises magnetic pigment.

7. A pressure-sensitive transfer element comprising a ilexible foundation having thereon a microporous inkreleasing layer comprising as the solid binder material a mixture of substantially incompatible synthetic plastic materials having dispersed therein a pressure-releasable ink comprising oil and coloring matter, the said mixture of incompatible synthetic plastic materials comprising lat least about 90% by weight of a vinyl resin together with up to about 10% by weight of a cellulose ether plastic whereby the tendency of the ink-releasing layer to cause the transfer element to curl and roll is substantially completely avoided.

S. A transfer element .according to claim 7 in which the cellulose ether comprises ethyl cellulose.

9. A transfer element according to claim 7 vin which the vinyl resin comprises a vinyl chloride-vinyl acetate copolymer.

110. A transfer element according to claim 7 in which the coloring matter comprises magnetic pigment.

References Cited by the Examiner UNITED STATES PATENTS 2,744,031 5/56 Mumma 117-36.1 2,800,077 7/57 Marron l17-36.l 2,893,890 7/59 Harvey 117-36.1 2,943,952 7/60 Clark 117-364 2,944,037 7/60 Clark 117-36.1 2,970,926 2/ 61 Findlay 1l7-36.1 2,984,582 5/61 Newman et al 117-364 2,989,493 6/61 Clark et al. 117-16.1 3,029,157 4/62 Sutheim et al 117-36.1 3,037,879 6/ 62 Newman et al 117-36.1

RICHARD D. NEVIUS, Primary Examiner.

20 MURRAY KATZ, WILLIAM D. MARTIN, Examiners.

Claims

1. A PRESSURE-SENSITIVE TRANSFER ELEMENT COMPRISING A FLEXIBLE FOUNDATION HAVING THEREON A MICROPOROUS INKRELEASING LAYER COMPRISING AS THE SOLID BINDER MATERIAL A MIXTURE OF SYNTHETIC PLASTIC MATERIALS WHICH ARE INCOMPATIBLE IN THAT THEY ARE INCAPABLE OF FORMING AN OPTICALLY CLEAR SOLID SOLUTION AFTER BEING DISSOLVED TOGETHER IN A MUTUAL SOLVENT AND AFTER THE SOLVENT HAS BEEN EVAPORATED, SAID BINDER MATERIAL HAVING DISPERSED THEREIN A PRESURERELEASABLE INK COMPRISING OIL AND COLORING MATTER, THE SAID MIXTURE OF INCOMPATIBLE SYNTHETIC PLASTIC MATERIALS COMPRISING AT LEAST ABOUT 50% BY WIEGHT OF A VINYL RESIN TOGETHER WITH A SUFFICIENT INCOMPATIBLE AMOUNT BY WEIGHT OF A SYNTHETIC PLASTIC MATERIAL WHEREBY THE TENDENCY OF THE INK-RELEASING LAYER TO CAUSE THE TRANSFER ELEMENT TO CURL AND ROLL IS SUBSTANTIALLY COMPLETELY AVOIDED.