US1874427A - Art of translucent printing - Google Patents

Description

Aug- 30, 1932- H. J. BILLINGS 1,874,427

ART oF TRANSLUCENT PRINTING Filed Aug.I 50, 1929 MS (M07 "7l t 'Patented Aug. 30, 1932 UNITED STATES PATENT OFFICE HOWARD J'. BILLINGS, OF SOUTH ACTON, MASSACHUSETTS, ASSIGNOR TO ARTHUR D. LITTLE, INCORPORATED, OF CAMBRIDGE, MASSACHUSETTS, A CORPORATION 0F MASSACHUSETTS ART OF TRANSLUCENT. PRINTING Application led .August 30, 1929. Serial No.v 389,434.

This invention relates to the art of printing, and especially to the art of printing translucent imprints upon very thin, absorbent 'sheets of paper or similar material.

Absorbent materials such, for example, as paper towels, paper napkins, toilet and tissue paper, differ considerably from printing, Wrapping, and Writing papers as Well as other types Which have been sized, coated or ,other- Wise rendered relatively non-absorbent, in

that they are soft and light, anld are eX- tremely absorbent to liquids. The various methods heretofore used in translucent printing and the like, comprising methods involving the use of marking materials Which dry by absorption, oxidation, or evaporation of the solvent vehicle, have not been successfully employed for producing a Well-defined mark on absorbent materials. Due to the aforesaid characteristics the vehicle or carrier spreads chines Wherethe paper making', finishing,y

lslitting and revvinding operations are carried` thin absorbent paper it has been found that before itY has had time to evaporate or set and consequently produces an objectionable blurring.

Paper is commonly manufactured on maon While the stock is traveling at a speed of approximately eight hundred linear 'feet a minute; In the manufacture of relatively it is not practica-l to attempt to trade mark .the 'stock Without first considerably slowing down the speed of the machine and hence retarding production.v For instance, in Watermarking by means of a Dandy roll at relativelyhigh speeds on a stock of a softffluiy nature, therefis a tendency to foul up the roll and to give yconsiderable operating diiiiculty from this cause. Moreover, a mark made by an engraved roll in the drier train is not as distinct or as Well defined as a true Watermark, VWhile embossingafter the paperhas dried has not been'successfully accomplishedY proportion of the total area passing-through` the machine. Furthermore, the embossing operation imparts a harshness to the sheet and Aalso increases the bulk sufliciently to give l a roll of larger diameter for the same number mately four or ive'hundred linear feet per minute due to the time required for the drying of the inks now available for this purpose. Relatively high speeds preclude the use of oily or resinous fluids which harden the oxidation, or by the evaporation of a solvent, While the porous structure of thin, absorbent sheets so favors the spreading of oily fluids that heretofore it has been impossible to secure sharp outlines by printing.

More specific purposesof this invention are to provide for producing a distinct, Well-defined mark upon paper or similar material, and especially upon very thin, absorbent paper, Whilethe latter is traveling at a relatively high rate of speed to provide for producing such a mark upon paper Without appreciably increasing the bulk or imparting objectionable harshness to .the sheet; to improve the art of printing, especially upon rapidly moving stock; to `provide an improved ink for printing upon rapidly moving stock, and especially uponthin, absorbent sheets; to provide relatively simple and efflcient means particularly adapted for embodiment in paper making and finishing apparatus and capable of operating in synchronism therewith even at the maximum operative speeds of such apparatus for printing upon thin absorbent sheets during the manufacture thereof; to provide a very thin absorbent sheet having a sharp, Well-dc- -ned vimprint thereon; and also to'provide' a very thin, absorbent sheet having a translucent imprint which will not spread When exposed to ordinary temperatures, and Which Will not 'oset Ifithe paper is to be used for toilet paper orother purposes which require it'to come in contact with the human body, it

4 is important that the printing fluid should be free from any injurious ingredients that would cause irritation of the skin or other- Wise harm the body.

Apparatus for practicing' 'this invention is shown in the accompanying drawing wherein Fig. 1 is a 'diagrammatic view of a rotogravure printing apparatus, and

Fig. 2 is a diagrammatic view of raised type printing machine in connection with paper making machinery.

In accordance with the present invention, printing upon sheets moving at a relatively high rate of speed, as for exampleY at eight hundred or more linear feet a minute, is made possible by the use of printing fluid which has the characteristic of drying or solidifying with sufficient rapidity to permit this as well as producing a sharp, well-defined imprint. This printing fluid 'consists of molten fatty, resinous, or waxy material which congeals at so high a temperature that when paper is printed with the molten material, the latter solidifies at temperatures within therange of room temperatures, i. e. temperatures normally encountered whether in the mill or the machine room where the product is made or in the room where it is ultimately used, and before it has had an opportunity to spread in the sheet, even though the sheet be of very thin, absorbent paper. This printing fluid also has the property of rendering paper translucent andisthercfore well adapted for vproducing a translucent imprint similar to a water-mark even upon very thin sheets of absorbent paper while thelatter is traveling at a high rate of speed; and it preferably is free from irritants of the human body.

The materials most suitable to this purpose are those melting well above a temperature of C., since tissue paper for household use frequently may be exposed to'the heat of a radiator, which would cause imprints. made with lower melting materials to spread. Materials that are particularly suitable are carnauba wax, ceresin, candelilla wax, stearic acid. guaiacum resin, and certain hydrogenated oils, such as hydrogenated sesamum oil, or mixtures of such materials. Relatively small amounts of carnauba wax, in', admixture with such `materials as paraffin, stearic acid, or ceresin, increase the congelation points of the latter materials very remark` ably. Fifteen per cent of cxarnauba wax, for example, in such a mixture frequently results in a congelation point not Very much lower than that of pure carnauba wax. However, if the melting point of the other constituent of the mixture is too low, imprints made with the aid of the molten mixture will spread when exposed to the heat of a radiator, thus defeating the purposefor which the carnauba wax lis introduced.

Accordingly, substances which may be used in the present invention may be designated generically as hard waxes, including by this term the higher members of both the hydrocarbons andfatty acids as well as paraffin, waxes and resins which are of sufficiently high melting point and which are of appropriate fluidity when in the liquid condi- `tion, and also mixtures of twoor more of these substances. While these hard waxes ,at present is a serious objection to the use of dyes. i

Since the hard waxes employed in this process become thinly fluid when melted, and under working conditions closely resemble rotogravure inks in consistency, it is recommended that thel printing be performed by the rotogravure process, the speed and other advantages of which are well understood.I

Moreover the rotogravure process by reason of its speed and other characteristics is welladapted for application to the machines for perforating and slitting the paper, thus making it possible to imprint the paper asl it comes through the perforator and slitter and so insuring correct registration and positioning of the imprintsupon the sheet, which is very difficult to accomplish by a separate printing machine as an independent operation after the paper leaves the perforator and slitter. i

The rotogravure printing apparatus shown in F ig. 1 consists of the cylindrical engraved roll 10, the latter preferably being arranged to dip in the bath 11 of molten hard wax in a container 12 lcorresponding tothe ink fountain of the usual rotogravure machine.

in the direction of the arrow and is scraped by the doctor knife 13 before the roll comes in. contact with thefsheet 14 which' is to be printed. The doctor knife removes the Amolten hard wax7 from all portions ofthe roll except the engraved pattern to be printed which is below the surface. The sheet of paper 14 passes between the roll 10 and an impression roll 15. The hard wax may be maintained in molten condition, preferably at about the consistency of water, by means of suitable heating coils in the bath; and the roll 10 may also .be heated if necessary, although the application of heat to the bath in this manner may be sufficient to maintain. the

proper temperature in the printing roll as With the molten hardvvax from container 17 I {heated by suitable coils) by means of an ink roll 18 and a transfer roll 19. The paper passes in the direction of the arrows from the usual paper drier 20, then between the printing roll 16 and the impression roll 21, then over the usual reel 22, which is driven at constant speed, and then the paper is Wound up into the finished printed roll 23.

Either raised type printing apparatus or rotogravure printing apparatus may be readily incorporated in paper .finishing apparatus so as to assure absolute register with the perforating, slitting and reWinding mechanism. The upper limit of permissible operating speed for the raised type head would be the highest speed at which the molten hard Wax will adhere to the printing head. This speed would not be greater than approximately five hundred linear feet a minute. It will be clear therefore, that Where speeds up to four or five hundred linear feet per minute are required, satisfactory results may be obtained by printing the molten hard wax With either the raised type or the rotogravure head, but `Where higher speeds are required the rotogravure head should be used exclusively.

I claim:

1. The method of marking absorbent paper and the like materials to produce an imprint thereon simulating a Water mark which comprises printing With a hot, molten iiuid which has the property of congealing at so high a temperature as to solidify immediately Without spreading at temperatures Within the range of room temperatures.

' prises printing the sheet With a hot, molten fluid which has the capacity for rendering the sheet translucent and which has the property of congealing at so high a ltemperature as to solidify and form a sharply defined imprint without substantial spreading through the sheet.

4. The method of marking absorbent paper and the like materials to produce an imprint thereon simulating a Water mark Which comprises printing with a hot, molten fluid which contains at least 15% of carnauba Wax and has the property of congealing at so high a temperature as to solidify immediately Without spreading at temperatures Within the range" of room temperatures.

5. The method of marking absorbent paper and the like materials to produce an imprint thereon simulating a Water mark which comprises printing With a hot, molten fluid which has the property of congealing at or above approximately C.

6. The method of marking absorbent paper and the like materials to produce an imprint thereon simulating a water mark which comprises printing With hot, molten hard Wax containing at least 15% carnauba wax and having the property of congealing at so high a temperature as to solidify immediately Without spreading at temperatures Within the range of room temperatures.

7 The'method of marking absorbent paper and the like materials to produce an imprint thereon simulating a Water mark which comprises printing With hot, molten hard Wax which has the property of congealing at'so high a temperature as to solidify immediately at temperatures Within the range of room temperatures.

8. The method of marking absorbent paper and the like materials to produce an imprint thereon simulating a Water mark which comprises printing by the rotogravure processv with hot, molten, hard Wax which has the property of congealing at so high a temperature as to solidify immediately at temperatures Within the range of'room temperatures.

9. The method of marking absorbent paper and the like materials to produce an imprint thereon simulating a Water mark which comprises printing With hot, molten hard Waar7 and an appropriate coloring agent, the hard Wax having the property of congealing at so high a temperature as to solidify immediately Without spreading at temperatures Within range of room temperatures.

10.' The method of marking absorbent paper and the like materials to produce an imprintthereon simulating a Water mark which comprises printing With a hot, molten fluid which is free from irritants of the human body and which has the property of congealing at so high a temperature as to solidify immediately Without spreading at temperatures `Within the range of room temperatures.

11. A sheet of absorbent paper having an imprint thereon simulating a Water mark, the imprint comprising a congealed substance impregnated in the paper and confined Within well defined outlines and adapted to render the paper translucent, said substance havng a congelation point preventative of spreading at temperatures Within the range of room temperatures.

12. A sheet of absorbent paper having an imprintV thereon simulating a Water mark, the imprint comprising a congealed substance free from irritants of the human render the paper translucent, said substance havin a congelation point preventative of sprea ing at temperatures Within the range of room temperatures. 13. A sheet of absorbent paper having a 5 translucent imprint thereon, simulating a Water mark, the imprint comprising a congealed substance containing at least 15% of carnauba Wax and being impregnated in the paper and conned Within Well defined outlines and adapted to render the paper translucent.

14. A sheet of absorbent paper having a translucent imprint thereon simulating a water mark, the imprint .comprising congealed carnauba waximpregnated in the paper and coniined Within Well defined outlines. 15, A sheet of absorbent paper having a translucent im rint thereon, simulating a Water mark, t e imprint comprising congealed hard Wax impregnated in the paper and confined Within Well defined outlines.

Signed byv me at Cambridge, Massachu--. setts, this 27th day of August, 1929.

HOWARD J. BILLINGS.

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