Other Classes:
101/32, 106/31.69, 106/31.82, 106/139.3, 106/156.22, 352/55, 355/39, 396/310, 428/474.7, 428/478.2, 428/914, 430/300, 524/18, 524/20, 530/372, 530/373, 530/376
Description:
This invention relates to titling materials which will, through the use of heated type, print a legend on developed photographic film and paper. In one aspect, the invention relates to a titling material comprising a transferable coating on a thin polymeric support which will, upon being struck by heated type, print a clear readable legend on either negative or positive photographic film.
In the manufacture of photographic image-bearing elements, the image-bearing element is ordinarily provided with symbols or numbers by which specified images can be identified. Frequently, indicator numbers are printed by standard printing techniques, e.g. between the edge of the film and the image. Although such method is standard procedure in the photographic industry, it is disadvantageous since the ink-printed numbers are difficult to read after processing because of poor reproduction and because of smearing which occurs during handling. Methods utilizing printing ink are particularly unsatisfactory because the numbers are susceptible to solvent action by standard cleaning solutions such as trichloroethylene, etc. and they are easily smeared by human or mechanical handling. Other methods that have been used in the past to provide identifying marks on photographic films also have serious disadvantages. For example, stencils have been used for cutting numbers into the film, but this procedure is cumbersome and frequently produces lacerations of the film.
Recently a material for printing on photographic film has been developed which consists of a polymeric support coated with a waxy layer containing carbon. The carbon-wax layer makes a satisfactory transfer to film when struck with heated type but the typed image must be protected by an overcoat to prevent smearing or dissolution in common cleaning solvents.
It is thus apparent that a need exists for a method of printing on negative or transparent positive film utilizing material which does not readily smear or smudge, which is evenly pigmented and which is deposited with a minimum of film base embossing. Such film printing material must further be insoluble in common film cleaning agents and must not transfer to the opposite side of the film if the film is rolled up.
In accordance with the present invention, it has been found that a film titling material comprising a thin polymeric support upon which there is coated a pigment suspended in a heat releasable vehicle is highly utilitarian in providing a method for titling film by the use of heated type. In such manner the pigment is transferred from the titling material to the film. The resultant printing does not readily smear or smudge; it is sharp and evenly pigmented and is deposited with minimum film embossing. The film titling material of the present invention does not transfer to the opposite side of the film if the film is rolled up and it is insoluble in commonly used film cleaning agents such as naphtha, methylchloroform, "freons," etc., but is soluble in commonly available organic solvents so that misprints or errors may be easily corrected.
Thus, the present invention provides a suspension of a finely divided pigment in a prolamine mixture, which suspension is coated from an organic solvent onto a support. The resulting element, when struck by heated type, will print a clear, legend on developed photographic film or paper.
It is, therefore, one object of this invention to provide film titling material which will print a clear, readable legend on developed photographic film or paper.
It is a further object of this invention to provide a printing element comprising a support coated with a suspension of a pigment in a heat sealing vehicle.
It is another object of this invention to provide processes for applying legends to processed film or paper by the use of heated type.
It is still a further object of this invention to provide processes for applying legends to processed film or paper whereby a pigment composition is transferred from a printing element to processed photographic film or paper.
The above objects and other objects which will become apparent to those skilled in the art are attained by the present invention wherein there is provided a printing element comprising at least two layers -- one layer being a polymeric support having a melting point above about 400° F. and another layer including prolamine, pigment, film-forming promoter and plasticizer.
The prolamine utilized in the composition of the invention may be prolamine derived from gluten, meal or maize. Particular proteins which are utilized in preparing the ink composition of the present invention include corn protein, e.g. zein, wheat protein and the like. Although zein is a preferred material, other prolamines which, in combination with plasticizer ad film-forming promoter, melt in the range of 150°-350° may be utilized.
It is the prolamine which apparently provides the characteristics which make the marking process of this invention superior to those of the prior art. Evaluation of a large number of materials including the wax-carbon products described briefly above indicates that the proteinaceous prolamine which is a homolog of gelatin and therefore highly compatible with gelatin provides the properties which give the transfer materials of this invention their improved adhesion to positive or negative photographic materials. Without this improved compatability which permits the prolamine layer applied to the gelatin coated photographic material to, so to speak, amalgamate with the gelatin layer, the titling applied to the photographic film would smear and be easily removed as in the case of the prior art materials.
This compatability of prolamine with gelatin is particularly evident in the case where the gelatin is a processed photographic emulsion of the type generally present in conventional photographic positive or negative materials.
In addition to the prolamine, the binder for the pigment also contains small amounts of a film-forming promoter to assure a firm coating that does not easily rub off and to assure a uniform image transfer. This promoter must, of course, be compatible with the prolamine and is usually selected from materials such as poly(vinyl alcohol), slightly hydrolyzed poly(vinyl alcohol), cellulose nitrate, etc.
The ratio of the prolamine, e.g. zein, to the film-forming promoter, e.g. low viscosity nitrocellulose, is important since the high film-forming properties of nitrocellulose will cause a ragged transfer of the printing medium unless the correct proportion is utilized. Conventionally a ratio of 10-2:1, zein to nitrocellulose, is utilized. A ratio of 4:1, zein to nitrocellulose, produces highly beneficial results. By increasing or decreasing the ratio of plasticizer to the corn protein, the heat sealing range of the composition can be varied.
The selection of the plasticizer utilized in the preparation of the ink of the present invention is important since the plasticizer must not be soluble in the commonly used solvents utilized during film cleaning. The plasticizer must, however, be soluble in certain conventional solvents so that the ink may be eradicated in the event of misprint or error. A plasticizer usually utilized is an alkyl acid phthalate including straight chain alkyl and cycloalkyl acid phthalates. Typical plasticizers include such compounds as dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dicyclohexyl phthalate and the like. A preferred plasticizer is a cycloalkyl acid phthalate such as cyclohexyl acid phthalate. Also polyalkylene glycol plasticizers such as Carbowax 400, Carbowax 700, etc. and glycol ethers, e.g. diethylene glycol, etc., may be used together with or in lieu of the phthalate plasticizers. The plasticizer-prolamine ratio advantageously is about 2-1:1.
The pigments utilized in the compositions of the present invention are those materials usually utilized in printing inks, e.g. such materials as a titanium oxide, e.g. titanium dioxide and various forms of carbon such as carbon black, Dixon graphite, zinc oxide and the like. The ratio of pigment to the vehicle in which it is suspended, e.g. zein, nitrocellulose and plasticizer is also important since the resultant image is very thin. There must be sufficient pigment transferred from the titling element to form easily readable images. The ratio of pigment to vehicle usually ranges between 1:0.1-5 depending inter alia, upon the weight density of the pigment.
The solvents used in coating the pigment suspension of the invention may be ethyl alcohol, e.g. 95% ethyl alcohol, isopropyl alcohol, etc. The concentration of the pigment and vehicle in solvent may be dictated by standard coating techniques but the solvent usually amounts to about half the total weight of the coating solution.
The thin polymeric base over which the ink suspension is coated is selected so that the heat of the type will release the ink cleanly from the base. Suitable components for the thin polymeric support include polyesters such as polyethylene terephthalate and cellulose organic esters including cellulose propionate, cellulose acetate, cellulose acetate propionate, cellulose acetate butyrate, cellophane and the like. The support should have a thickness of about 0.0005 to about 0.002 inch in order that the tape will be heated quickly by the type when transferring the ink suspension to the film. In addition, the support may be coated by materials which will facilitate the heat release and stabilize the resultant image to an even greater degree. The transfer from the coated polymeric support can be made to either the emulsion or the support side of photographic film or paper. The photographic support is, of course, not critical and many examples are conventionally known in the art.
The pigment suspension is coated onto the thin support from a solvent at a thickness of from about 0.0005 to about 0.0015 inch.
The titling element of the present invention which as just described comprises a polymeric support having first and second support surfaces, the first support surface being coated with a layer comprising prolamine, film forming promoter, plasticizer and pigment to provide a printing surface is utilized according to the process of the present invention by:
1. juxtaposing the photographic film and the titling element, the printing surface of the titling element being adjacent the photographic film;
2. striking the second support surface of the titling element with heated type to bring the printing surface of the titling element into contact with the photographic film for a period of time sufficient to transfer selective portions of the surface having the configuration of the heated type to the photographic film without transfer of any portion of the polymeric support; and
3. withdrawing the printing surface of the titling element from the photographic film to leave the selected portions of the printing surface on the photographic film.
The type may be, for example, electrically heated type having a temperature between about 250° and 350° F and preferably between about 300°-350° F. The striking of the printing element of the invention by the heated type thus transfers the pigment suspension from the thin polymeric support to the photographic film which is to be titled.
The invention will be more fully illustrated by the following examples.
EXAMPLE 1
A suspension of finely divided graphite in a heat sealing adhesive vehicle is prepared from the following materials:
Components Parts by Weight __________________________________________________________________________ Zein 7.5 Cyclohexyl acid phthalate 13.0 Graphite 24.0 Nitrocellulose, 1/4 second ss. (low viscosity) 2.0 Ethanol (95%) 50.0 __________________________________________________________________________
The suspension is coated on a 0.0015 inch thick poly(ethylene terephthalate) support. The solvent is evaporated leaving a firm, uniform coating on the support. This material is then utilized with heated type (about 325° F.) to print legends on photographic film as described above. The legends are easily readable, stable to cleaning solutions and relatively smudge free.
EXAMPLE 2
A suspension of finely divided graphite in a heat sealing adhesive vehicle is prepared from the following materials:
Components Parts by Weight __________________________________________________________________________ Zein 8.5 Cyclohexyl acid phthalate 15.0 Graphite 25.0 Nitrocellulose, 1/4 second ss. 3.0 Ethanol (95%) 53.0
The suspension is coated on a 0.0015 inch thick cellulose acetate support. The solvent is evaporated leaving a firm, uniform coating on the support. This material is then utilized with heated type to print legends on photographic film. The legends are easily readable, stable to cleaning solutions and relatively smudge free.
EXAMPLE 3
A suspension of finely divided graphite was prepared from the following materials:
Components Parts by Weight __________________________________________________________________________ Zein 20.0 Cyclohexyl acid phthalate 35.0 Nitrocellulose, 1/4 second ss. 7.5 Dixon graphite (200-39) 65.0 95% Ethyl alcohol 140.0 __________________________________________________________________________
The suspension is coated on a 0.0015 inch thick cellulose acetate propionate support. The solvent is evaporated leaving a firm, uniform coating on the support. This material is then utilized with heated type to print legends on photographic film. The legends are easily readable, stable to cleaning solutions and relatively smudge free.
EXAMPLE 4
A suspension of finely divided graphite is prepared from the following components:
Components Parts by Weight __________________________________________________________________________ Zein 8.0 Carbon 20.0 Cyclohexyl acid phthalate 5.0 Carbowax 400 14.0 Ethyl alcohol (95%) 48.0 Silica smoke 4.2
The suspension is coated on a 0.0015 inch thick cellulose acetate butyrate support. The solvent is evaporated leaving a firm, uniform coating on the support. This material is then utilized with heated type to print legends on photographic film. The legends are easily readable, stable to cleaning solutions and relatively smudge free.
The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove.