Патент USA US2136176код для вставки
Patented Nov. 8, 1938 2,136,176 UNITED STATES . PATENT OFFICE amass vr'no'rormolm‘Into ‘ John M. Hammond, Washington, D. 0., claim to The Varnish Products Company. Cleveland, Ohio, a corporation of Ohio No Drawing. Application October I0, 1887, Serial No. 112,054 90mins. (C1- 41-33) like mass; the jelly-like mass tamed by the dis This invention relates to the art 0! photoen graving and more particularly to what is known solved gelatin greatly retards evaporation of the in the photoengraving industry as "stripping" solvent regardless of the solvent used; the nega and to a new and improved stripping method 5 and a solution by means of which the method of stripping may be e?ected. - In the photoengraving process a photographic negative is produced. This negative comprises a sensitized nitrocellulose ?lm, which is sup 10 ported on a suitable support such as a glass plate. After the negative has been developed it becomes necessary. because of the require ments of the printing industry, to reverse this image from left to right. Therefore, it be comes essential to remove this image-bearing I?lm of nitrocellulose from the glass plate and to place it upon another supporting plate, usually of glass, in a reverse position. This operation of removing the image-bearing ?lm from the 20 glass plate is known in the photoengraving art as "stripping.” The ?lm of nitrocellulose is an extremely deli cate one and does not of itself have sui?cient. strength to withstand the operation of strip ping. For this reason the practice in the craft has been to coat the ?lm oi nitrocellulose with a reinforcing-medium or layer 01' a character which will give it the necessary strength to with stand handling. 30 For a number of years in the early days oi! photoengraving stripping was effected by coat ing a nitrocellulose ?lm with a thick aqueous solution of gelatin. This method consists of pouring the gelatin solution onto the image bearing surface of the nitrocellulose ?lm ad herent to the glass plate, while the plate is on a "leveling stand",-supporting the plate on the leveling stand until the water has evaporated from the gelatin, thereby forming a layer or ?lm 40 of dry gelatin over and in contact with the nitro cellulose ?lm, and alter the gelatin has dried. stripping the combined nitrocellulose and gelatin film from the glass by immersing the negative in a simple acetic acid solution. The ?lm of 45 nitrocellulose is insoluble in water so that the" tive has to be stripped with" extreme care to pre vent tearing of the image—bearing ?lm and dis- ‘ tortion oi the image by stretching; the com posite ?lm has to be placed on the second sup-, port very carefully so that it will not stretch or become distorted; it is di?icult to make the composite ?lm adherent to the second support 1. without tearing; the method also necessitates a large amount of storage space wherein the plates can be stored in leveled condition during the drying of the gelatin: the gelatin deteriorates very rapidly when it is‘ subjected to atmospheric 1; conditions, fungi or bacteria, and it it is ?rst prepared by a manufacturer, it is necessary to use extreme care and a container with a type of sp: clal lining for maintaining it in its original useful condition until it reaches the hand of its no consumer; and the ?lm formed does not have the necessary properties of hardness, tensile strength, and ?exibility to prevent distortion and tearing under the usual conditions of present day photoengraving practice. Because oi’ the g5 disadvantages inherent in the gelatin method of stripping, it was proposed that, instead’ 0!’ gela tin, the reinforcing layer also be formed of nitro cellulose. Since a solvent for nitrocellulose would attack the original ?lm, it was not pos- m sible to apply the second layer of nitrocellulose directly to the image-bearing ?lm. ‘ Due to these dii?culties, a stripping method was developed which included the steps of ?rst coating the negative with a solution 01' India rubber in 35 benzol, permitting evaporation of the benml so as to leave a protective cover or coating of rub her over theimage-bearing nitrocellulose ?lm. then iorming a nitrocellulose ?lm on the rub ber coating. by applying over the rubber coating 40 a nitrocellulose solution.‘ ,_-- -‘> 1, ‘ This m‘ethodis much more satisfactory and speedy than the earlier method using gelatin, but it has certain disadvantages, particularly in that two coating operations are required to strip 45 water of the gelatin solution has no e?ect on the the image-bearing ?lm. nitrocellulose ?lm. One or the principal objects of the present invention is to provide a stripping solution and method of stripping whereby the disadvantages A disadvantage of the method just described is that it requires a considerable period of ‘time 50 for the water to evaporate from the gelatin solu tion and the plate has to be kept pertectlylevel until the gelatin solution has lost its liquid char acter. Further disadvantages of the method utilizing the gelatin solution are that: it is dii’ It ?cult to make a proper solution of the jelly ‘ oi’ both oi’ the previous methods are eliminated 50 and the stripping operation is e?ected more quickly and with a single coating operation, and certain steps which are necessary in the prior methods are eliminated. An equally important object is to provide a so 2 2,186, 176 method oi’ stripping an image-bearing negative photographic ?lm, which method includes the steps of applying, directly on the image~bearing ?lm, a ?lm forming solution capable of deposit ing, by simple evaporation, a dry, hard, tough. transparent Stripping ?lm of adequate tensile strength and ?exibility to permit handling un der the usual conditions of work prevailing in xylol is desirable in warm humid weather because the lowering of temperature which would be caused by the rapid evaporation of ethylene di chloride under such conditions would be apt to cause precipitation of water upon the ?lm. This eifect is called "logging" and impairs the trans~ parency of the ?lm. When the image-bearing nitrocellulose ?lm has been coated with the the solvent has evaporated, the image-bearing ?lm can be stripped irom the glass either by im mersing it in water or in a weak aqueous solution of acetic acid. in some cases it may be de 15 sirable to combine a small amount of acetic acid with the stripping solution to facilitate the strip ably free from stretching, shrinking, and tearing. 20 A correlative object is to provide a method of transferring an image-bearing negative photo graphic ?lm from its original plate to another plate and which comprises applying to the ping of thl;3 ?lm in plain water. It‘ is not neces sary, however, that acid be used at all, Under some circumstances the tion may have a dye substance incorporated therein to render the resulting ?lm opaque to actinic light. image-bearing surface of the photographic ?lm a. solution of cellulose derivative which is soluble in and dissolved in hydrocarbon solvent or sol vents which do not deleteriously affect the under lying image-bearing ?lm and which may be evaporated for depositing the cellulose derivative as a ?lm on the image-bearing surface, and 30 stripping the resultant composite ?lm from the original plate and depositing the same onto an other supporting plate. Another obicct is to 35 40 40 45 Other objects and advantages parent from the following speci?cation, wherein 45 60 out my method, be understood that the invention contem~ or an ester of cellulose, such as a product mar keted commercially under the trade name "Her cose C", by the Hercules Powder Company of Wilmington, Delaware, and which is a cellulose aceto-butyrate, and a solvent which may be a plates the use of the recognized equivalents therefore. I claim: 1. The method of stripping an image-carrying nitrocellulose ?lm from a hydrocarbon solvent, for example, ethylene di chloride or‘ xylol or any other suitable solvent 60' which does not deleteriously, a?ect the image bearing ?lm. _A solution otthe foregoing char mersing the plate in water. ‘ . Oil 2. The method of stripping an image-carrying solvent does nojtdissolve or attack the image nitrocellulose ?lm from a glass plate which com bearing ?lm, it is unnecessary to use, any pro~ tective layer ofIndiarubber or other protective material. , ,, . 65 - vllli‘i'iere extremeiy quick drying Tls desired ethylene dichloride is preferred as a. solvent as it evaporatesirom the stripping solution very rapidly. , _. Where slower evaporation is desired. the xylol or some other solvent which does not delete riously affect the image-bearing ‘?lm and which evaporates 'less rapidly, is used. For example, 3. The method of photographic negative having an underlying image-bearing ?lm of ‘nitrocellulose compound which is super imposed upon and adherent to a plate, which comprises‘ in applying directly ‘on the surface of the image-bearing nitrocellulose compound ?lm, lil 3,186,176 a ?lm iorming solution oi’ a solute of essentially water-insoluble material and an evaporable sol vent- which does not a?'ect the nitrocellulose him and image, and capable of depositing on the Cl nitrocellulose compound ?lm without detrimen tally affecting the nitrocellulose compound ?lm and image, by evaporation of the solvent, an ad herent, translucent film of adequate tensile strength and flexibility to permit handling under the usual conditions of photoengraving work, effecting evaporation of the solvent, and strip ping from the plate, the combined solute ?lm and nitrocellulose compound image-bearing ?lm. 4. The method of stripping a photographic negative having an image-bearing layer of nitro cellulose which is superimposed upon a plate which comprises applying directly on the sur face 01' the negative a coating of solution essen; tially of cellulose derivative and evaporable sol vent which solution does not detrimentally affect said layer of nitrocellulose and image, evaporat ing the solvent, and thereby depositing on the from the original supporting plate and disposing negative, without detrimentally ‘affecting said iayer a solution essentially of cellulose derivative and evaporable solvent from the group consisting of ethylene dichloride and xylol, which solution does not detrimentally ai'lect the image-bearing‘ layer and the image, effecting evaporation of the solvent to dispose the cellulose derivative as an adherent coating on the surface of the image nitrocellulose layer and image, an adherent strip— ping ?lm, and then stripping the composite ?lm and negative from the plate. 5. In the photoengraving process employing as a negative a sensitized image-bearing nitrocel lulose layer adherent to a support, the method of stripping the negative from the support and comprising applying on the negative a coating of a solution essentially of cellulose derivative and evaporable solvent, which solution does not detrimentally a?’ect the nitrocellulose layer and 35 image, drying the coating to cause it to adhere to the nitrocellulose layer as a tough ?exible film and without detrimentally affecting the nitro cellulose layer and image, and then stripping the coating with the nitrocellulose layer adherent 40 thereto from the support. it onto said other plate. 7. In the phcteengraving process empioying an image-bearing nitrocellulose layer, the method of transferring the image-bearing nitro (.1 cellulose layer from a supporting plate which comprises applying directly on the image-bearing surface of the nitrocellulose layer, a solution essentially oi’ translucent cellulose derivative and evaporable hydrocarbon solvent which does not . . detrimentally a?ect the nitrocellulose layer and the image, effecting evaporation of the solvent to render the cellulose derivative adherent to the nitrocellulose layer as a substantially uniform coating on the said surface, and then stripping the resultant combination from the plate and transferring the combination to another support. 8. The method of stripping a photographic negative having an underlying image-bearing layer of nitrocellulose which is superimposed upon and adherent to a plate. comprising apply ing directly on the surface of the image-bearing bearing layer without deterioration of the image bearing layer and image, and then stripping from the original supporting plate the combined solute coating and image-bearing layer. 9. The method of stripping a photographic negative having an underlying image-bearing layer of nitrocellulose which is superimposed upon and adherent to a plate, comprising apply ing directly on the surface of the image~bearing layer a ?lm forming solution essentially of evaporable solvent, which does not detrimentally _ 6. The method of transferring the image-bear ing nitrocellulose layer from its original sup porting plate to another supporting plate which comprises applying on the image-bearing surface affect the image-bearing layer, and cellulose matter from the group consisting of ethyl-cel lulose and cellulose aceto-butyrate, depositing on the image-bearing layer by evaporation of the of the nitrocellulose layer a solution essentially of a hydrocarbon soluble cellulose derivative and an evaporable hydrocarbon solvent which does not detrimentaily affect the nitrocellulose and tensile strength and ?exibility to permit handling under the usual conditions of photoengraving image, e?‘ecting evaporation of the solvent to dispose the solute as an adherent coating on the said surface of the nitrocellulose layer without deterioration oi.’ the nitrocellulose layer and image, then stripping the resultant combination solvent, an adherent translucent ?lm of adequate work and without detrimentally affecting the image-bearing layer and image, and then strip ping from the plate, the combined translucent ?lm and the image-bearing layer. JOHN M. HAMMOND.