US2316120A - Decalcomania paper - Google Patents

Description

Patented Apr. 6, 1943 2,316,120 nEcALcoMnNIA PAPER.

John MacLam-in, Ware, Mass, assignor to Mc- Laurin-Jones 00., Brookfleld, Mass, 9. corporation of Massachusetts No Drawing. Application August 11, 1939, Serial No. 289,631

7 Claims.

As is well understood by those familiar with decalcomania papers and the manufacture of them, it has been practically the universal custom to use a water-leaf backing sheet in the manufacture 01' papers of this type. in my prior Patent No. 2,038,118, granted April 21, 1936, I have disclosed an improvement in this practice involving the use of a sized backing sheet in order to avoid the tendency inherent in a waterleaf sheet to change in dimensions with wide changes in atmospheric humidity. The fundamental reason for using the latter sheet is to. take advantage of the exceptionally high rate of water absorption by a paper orf this character and thus to efiect a quick release of the decalcomania print during the application of the same to the work. When a sized backing sheet is employed in accordance with the invention described in said patent the releasing period, which otherwise would be excessive, is reduced to reasonable limits by the use of a releasing liquid consisting of water in which some wetting agent is dissolved. This agent so reduces the surface tension of the water that it penetrates the sized backing sheet rapidly and thus accomplishes the release in a time period comparable to that realized when a water-leaf backing sheet is used. Thus the more stable characteristics of the sized backing sheet can be utilized with a reasonably brief releasing period.

The commercial use of this sized backing decalcomania paper, however, is handicapped by the fact that a special releasing liquid must be used with it. There is also the objection that the workmen may not make the releasing solution properly, with the result that difiiculty will later be experienced in using it.

The. present invention deals especially with these conditions. It aims to devise a sized backing decalcomania paper and a method of making it which will place the control of the releasing period as completely in the hands of the manuiacturer as is the case with a water-leaf backing decalcomania paper, which will avoid the necessity for using a special releasing solution and will enable the workmen to accomplish the releasing operation by the methods to which they are already accustomed. In other words, it proposes to secure the advantages of the sized backing sheet in a decalcomania paper without depending on the workmen to depart in any measure from the common practice or using decalcomanias of the type with which they are familiar.

Accomplishment of these objects is complicated by the fact that his important to prevent the penetration of the decalcomania adhesive into the backing sheet. In other words, one of the diillculties in manufacturing a satisfactory decalcomania paper is to make the adhesive solution ride on the surface of the paper while it is drying, and this is customarily accomplished by giving the paper an initial coating with a starch solution, an important function of which is to prevent penetration of the subsequently applied gum coat.

One method of accomplishing this result ac- I cording to the present invention is to apply the coat or coats of decalcomania adhesive, to dry the web, and thereafter to apply the wetting agent, dissolved in a suitable solvent, to the side 0! the backing sheet opposite to that to which the decalcomania adhesive has been applied.

It is also possible to apply the penetrating agent to the backing sheet before the application of the decalcomania adhesive, drying the sheet between these two coating operations. However, this makes more diflicult the problem out controlling the penetration of the decalcomania adhesive coatings in to the sheet.

A disadvantage of both of these methods is that each necessitates an extra coating and drying operation.

I have found, however, that it is entirely practical to apply the penetrating agent during the gum. coating operation. That is, the solution of the wetting agent may be applied by means of a brush or roll to one side of the backing sheet approximately simultaneously with the application of the decalcomania coating solution to the opposite side thereof. At present it is preferred to make the application of the penetrating agent to the web of paper as it emerges from the coating machine which is applying the decalcomania adhesive.

An answer to the problem of preventing any substantial mixing or intermingling of the solid constituents of the two coating materials has been discovered, consisting in making the solutions of such a nature that they will not be miscible in the sheet. For example, the decalcomania adhesive is usually dissolved in water and this solution, with its viscosity properly predetermined, is applied to the web of backing paper. Many of these wetting agents are readily soluble in alcohol, and if applied, as just described, while so dissolved, the two solutions will not mix, notwithstanding the fact that alcohol and water are readily miscible under ordinary conditions. In ract,'the solution of decalcomania adhesive place.

is of such high concentration, usually about 50% of solids, that while the alcohol solution of wetting agent strikes rapidly through the wet backing sheet, when it meets the adhesive solution it tends to precipitate the solids suspended in the latter and no material mixing of the two takes This is a surprising result and it makes this method preferable to either of the other two.

Thus in all of the foregoing methods the application of the penetrating agent is made under such conditions that it does not seriously increase the penetration of the adhesive into the sheet.

A considerable variety of penetrating or wet ting agents may be used. In general, as above indicated, they have the characteristic of reducing the surface tension of the water so that it will penetrate the sheet at a rate much faster than that due simply to the capillary attraction of the paper for water alone. Very satisfactory wetting agents are the alkyl aryl and alkyl naptholene sulphonate. A 2% solution of either of these materials in grain alcohol can be applied to the backing web of paper simultaneously with the adhesive coating or gumming operation with entirely satisfactory results. Sulphonatedl higher alcohols of this type are readily obtainable on the market under the names of Gardinol and Nekal. Other penetrating agents, however, can be used in place of them such, for example, as sulphonated oils; sulphonated esters of dicarboxylic acid and their sodium salts; complex methyl esters of high molecular weight alcohols, acids and lactones; fatty acid salts of aminosubstituted aliphatic alcohols and their isomers; sodium salts of sulphonated lauryl and myristyl collamide and others. Most of these, with the exception of the sodium compounds, are soluble in alcohol, and the latter compounds may be dissolved in benzol, acetone, or ethyl acetate.

These penetrating agents are solid at normal temperatures; they do not have hygroscopic properties which are material in the uses here made of them, and they do not materially affect the color of the paper.

From the foregoing it will be appreciated that the invention provides a decalcomania paper in which the advantages of the sized backing sheet are obtained while the releasing period may readily be made comparable to that of a waterleaf backing decalcomania paper. In using this product 'no departure from the practice with which the workmen are familiar is required, and the advantages of the invention are obtained without depending upon the user to perform some special operation to which he is not accustomed. In addition, the invention provides a method of manufacture which does not materially increase the cost of the product.

While I have herein disclosed a typical embodiment of my invention and a preferred method of procedure, it will be understood that considerable variation may be made in details of the process or the product without departing from the spirit or scope of the invention.

Having thus described my invention, what I desire to claim as new is:

1. A decalcomania paper comprising a backing sheet sized suiilciently to make it stable in dimensions under wide changes in atmospheric humidity and having a surface coating adapted to be printed upon, said coating having a water soluble adhesive union with said backing sheet, said sheet being impregnated with a sumcient proportion of a wetting agent to give the decalcomania paper a releasing period approximately equal to that of a'water-leaf sheet, said watersoluble adhesive constituting a distinct coating or film substantially free of penetration into the backing sheet and substantially unmixed with the wetting agent.

2. A decalcomania paper comprising a backing sheet containing a suiflcient quantity of a water-resistant sizing to render the sheet substantially unaffected in dimensions by wide changes in atmospheric humidity, a surface coating on one face of said paper adapted for the printing of a decalcomania design thereon, said coating having a water-soluble adhesive union with said backing sheet, said sheet containing a sufi'icient proportion of a wetting agent to reduce the surface tension of the water used in releasing said coating to a degree such that the water will penetrate the backing sheet substantially as rapidly as it does a water-leaf sheet, said water-soluble adhesive constituting a distinct coating or film substantially free of penetration into the backing sheet and substantially unmixed with the wetting agent, the entire sheet, including said coating, being calendered and its opposite surfaces therefore being made hard and smooth.

3. That improvement in methods of making a decalcomania paper having a backing sheet of paper sized sufi'iciently to make it stable in dimensions under wide changes in atmospheric humidity, comprising the steps of applying an aqueous dispersion of decalcomania adhesive to one side of said sheet, the proportion of solid constituents in said dispersion being sufficiently great to prevent any substantial penetration of said constituents into the sheet, while the backing sheet is wet with said dispersion applying to the opposite side of said sheet a wetting agent dispersed in a non-aqueous solution which is not miscible in. the sheet with said aqueous dispersion, and thereafter drying and calendering the sheet so treated.

4. That improvement in methods of making decalcomania papers, which consists in applying a coating of decalcomania adhesive to one side of a backing sheet of paper sized sufficiently to make the sheet stable in dimensions under wide changes in atmospheric humidity and, approximately simultaneously with said applying operation, applying to the opposite side of said sheet a wetting agent dispersed in a solution which is not miscible in the sheet with the solution of said adhesive coating material.

5. That improvement in methods of making a decalcomania paper having a backing sheet of paper sized sufi'iciently to make it stable in dimensions under wide changes in atmospheric humidity, comprising the steps of applying an aqueous dispersion of decalcomania adhesive to one side of said sheet, the proportion of solid constituents in said dispersion being sufiiciently great to prevent any substantial penetration of said constituents into the sheet, drying said sheet, applying to the opposite side of said sheet a wetting agent dispersed in a solvent which is not miscible in the sheet with the adhesive coating material, and thereafter drying and calendering the sheet.

6. That improvement in methods of making a decalcomania paper having a backing sheet of paper sized sufliciently to make it stable in dimensions under wide changes in the atmospheric humidity, comprising the steps of applying an aqueous dispersion of decalcomania adhesive to one side of said sheet, the proportion of solid constituents in said dispersion being Sulfflciently great to prevent any substantial penetration of said constituents into the sheet, while the backing sheet is wet with said dispersion applying to the opposite side of said sheet a wetting agent dispersed in an alcohol solution, and thereafter drying and calendaring the sheet so treated.

7. That improvement in methods of making a decalcomania paper having a backing sheet of paper sized sufilciently to make it stable in dimensions under wide changes in atmospheric humidity, comprising the steps of applying an aqueous dispersion'of decalcoman'ia adhesive to one side of said sheet, the proportions of solid constituents in said dispersion being sufficiently great to prevent any substantial penetration of said constituents into the sheet, applying to the opposite side of said sheet a wetting agent dispersed in a non-aqueous solvent which is not miscible in the sheet with the adhesive coating material, and thereafter drying and calendering the sheet.

JOHN MACLAURIN.