US2281909A - Printing stencil and method of making the same - Google Patents

Description

May 5, 1942.

G. BARSKY ETAL PRINTINGv STENCIL'AND METHOD OF MAKING TH 'SAME 7 Filed March'z, 1940 i IlllIIIIIIIHIIIIIIIIIIIIIIIII WiL-N Il|lllllmlllllflllllilllIIIIIIHIIIIIllll ff f Patented -May 5A, 1942 f PRINTING STENCIL AND METHOD OF MAKING THE SAME George Barsky, New York, and Frank A. Strauss, Staten Island, N. Y., assignors to Alfred S.

Daneman, Dayton, Ohio Application March 26, 1940, Serial No. 326,072 c'oiaims. (ci. i1-38.6)

This invention relates to new and useful imb provements in the art of surface ornamentation, and relates more particularly to an improvement in the process of printing by the silk screen method wherein a mechanical negative of the design to be reproduced is formed on a screen of bolting cloth, silk, or other foraminous material, such screen being tightly mounted in a frame. After the screen has been prepared, the design is printed by forcing a printing paste or other coloring material through the screen and onto the surface to be ornamented.

A-valuable contribution to the art of silk screen reproduction and particularly to the method of preparing the mechanical negative was disclosed in DAutremont Patent No. 1,781,834, wherein a unitary, homogeneous transparent lrn of approved thickness was formed on a substantially transparent backing sheet of paper or the like.

The lm was usually formed of nitrocellulosic however, as to prevent easy removal of the lm during the operation of cutting portions thereof corresponding to the design to be reproduced.

.u After the iilm had been so cut with the aid of la knife upon which suiiicient pressure was lexerted to cut through the film but not through the paper backing, and the cut portions removed from the main body of the lm, such film was caused to adhere to the screen by placing the lm in contact therewith and then rendering the film adhesive by the application of a solvent thereto. The opposed surfacesof the film thus exhibited alternate hospitaliies, the degree `of adhesion for the silk being far greater than for the paper backing or carrier sheet. After the solvent had dried, the paper backing was stripped and the stencil ready for printing.

A stencil sheet of the type just described has proven far more eifective than the old brushin method wherein the entire mechanical negative was formed cn the silk by means of a brush, for in cases wherein the design had considerable intricate detail the task was a long one,

the edges were not sharp, andthe life of the lm, and what was far more serious, caused the lm to separate from the screen. Thus, the silk screen industry, which in recent years had risen from a mere novelty in surface decoration to an important place in the major graphic arts, as a result of the creation of the foregoing stencil sheet, was entirely unsuit'ed for textile printmg.

The object of the present invention is to provide `means for employing this stencil sheet method in connection with the ornamentation of fabrics such as piece goods, as well as for printing designs in one or more colors on textile articles, such as handkerchiefs, ties, tablecloths and the like.

The foregoing method of employing nitrocellulose film and silk bolting cloth cannot be used for printing on textiles for the reason that the alkali in the printing paste and dyes attacks the silk, thus weakening the bers and accordingly oosening the bond between the lm and the silk, and the edges of the film become serrated and chipped.

We have discovered, however, that by a proper choice of composition for the lm, proper choice of `composition of the foraminous screen, and a proper choice of solvents for adhering the lm to the screen, a stencil screen may be prepared which is suitable for printing on textiles with alkaline materials.

Among the compositions which can be used for the film We have obtained good results with a plasticized vinyl resin lm, or with a lm formed of cellulose ethers, such as benzol cellulose, ethyl cellulose and methyl cellulose.

'Ihese cellulose ethers form a particularly tough film which is highly resistant to the alkaline dyes.

' stencil sheet suitable for this purpose, we prefer screen was short. The use of the stencil sheet .tion with three (3) parts of sperm oil, and one (l) part of hydrogenated methyl abietate.

A lm of this character must have an' approved measure of flexibility, and in order The solution just mentioned is made: up as follows:

If desired, the unal mixture may be diluted further with a suitable solvent, and this composition is deslrablyA applied to the backing material of glassine paper by means of a coating machine, although if desired it may be sprayed or even applied with a brush. The laminated stencil sheet, which is substantially transparent, may now be placed over` the design to be reproduced. and such design cut and the portions corresponding to the design removed in the manner described in the foregoing patent, No. 1,781,834.

'Ihe method of preparing the printing stencil constituting the present invention is illustrated generally in the drawing, in which:

Fig. 1 is a plan view of a stencil sheet with several layers of the laminated lm successively broken away. y

Fig. 2 is a plan view of a design to be reproduced.

Fig. 3 is a plan view of a stencil sheet wherein `the film has been cut and a portion thereof partially stripped away.

Fig. 4 is a broken section taken through a printing stencil showing the foraminous material and the stencil adhesively secured thereto, a. portion of the paper backing having been stripped away.

The stencil sheet designated by the reference numeral I comprises a backing sheet or carrier sheet II, which is preferably made from laminated glassine paper, as aforesaid, such paper being substantially transparent. By forming this backing sheet of laminated paper, the possibility of a knife cut penetrating the same is considerably lessened, and a laminated paper also has more body and is generally more suited for the present purpose than single ply paper.

The paper is first given a coat of rubber cement I2, which effectively prevents the lmforming material applied thereafter from penetrating the fibers ofthe paper and generally regulates the degree of adhesion between the film and the backing sheet. The film I3 is made from the materials previously described, and is desirably applied to the paper with the rubber cement coating by means of a coating machine. Inasmuch as such films must preferably be of a thickness of iive-thousandths of an inch, or thereabouts, the stencil sheet is run through a coating machine two, three or four times in order to build up a unitary, homogeneous film of this thickness.

In Fig. 2 a design to be reproduced is designated generally by the reference numeral I 5, and includes a star I6 enclosed by a substantially rectangular area I1, such area being surrounded by a border portion I8. In this instance we will assume that the star is to be of the same color as the original textile fabric, and accordingly only the portions between lines I9 and 20 are to be colored. Thus a negative is made corresponding to positive area I'I.

The stencil sheet I0 is placed over the design to be reproduced and is secured thereto by gummed tape or otherwise, and a small knife is then employed to cut the film along lines I9 and 20 defining star I6 and area I1, such lines being shown in Fig. 3 as 24 and 25, respectively. 'I'he artist then inserts his knife under one corner 21 of the rectangular portion 22 and begins peeling the nlm from this area. This peeling operation does not remove the star portion 2| because of cut line 24, and such portion remains upon the paperbacking in its proper position relative to portion 23.

The stencil sheet is then placedy film side against the screen of foraminous material, indicated by the reference numeral 30, and the solvent applied to the upper surface of the foraminous material, thus causing the film I3 to become securely bound to the fabric III. As soon as the solvent dries the paper backing II may then be readily stripped and the stencil ready for printing, as indicated in Fig. 4. The printing edges 3l of the stencil are thus firmly bonded to We prefer that the artificial fiber have a fair I measure of elasticity in order that it may be properly secured onto a frame and will remain relatively springy under conditions of use, and so retain its shape and also maintain accuracy of design during the printing process.

The choice of solvents for cementing the film to the screen is also highly important. We prefer to use a solvent combination which will quite definitely soften the film but effect the fabric only slightly. In fact, it has been found that a far better bond is obtained if the fabric is affected slightly by the solvent. It must not, however, be dissolved.

When the material of the fabric is swelled slightly and the fllm softened, the subsequent I pressing together of the two will cause a migration of one composition into the other, so that i on evaporationof the solvent a highly effective bond between the film and the screen is obtained. We have also found that a highly effective printing stencil of the screen type may be made by employing substantially the same composition both for the fabric and for the film. For example, we have used a vinyl resin fabric and a plasticized vinyl resin film, and cemented the film to the fabric. In this way a substantially homogeneous chemical structure is obtained in which the alkali resistance of one part is practically the same as that of the other. In addition to this, the bonding of such a composition is practically perfect, as there must occur complete fusion since both compositions are substantially the same and are-dissolved in the same solvent.

In making the printing stencil in this fashion, however, caremust be exercised in the application of the solvent in order that the screen is not dissolved sufficiently to materially reduce its strength. We have found that a suitable solvent for our purpose is a mixture of equal parts of toluol, ethyl acetate and butyl actate.

It will be appreciated that many changes and modifications may be made in the foregoing printing stencil and method of making the same without departing from the spirit of the invention `screen and a lrn cemented thereto, the lm having openings therein corresponding to a design to be reproduced, said screen being formed from a vinyl resin comprising the copolymer-of vinyl acetate and vinyl chloride.

3. A printing' stencil comprising a foraminous screen and a film adhesively joined thereto, the film having openings therein corresponding to a design to be reproduced, said screen being formed from material selected from a class consisting of vinyl resin, acrylate resins, and polyamine-polybasic acid resins.

4. A printing stencil comprising a foraminous screen and a lm cemented thereto, the film having openings therein corresponding to a design to be reproduced, said screen being formed from a vinyl resin spun into a fabric, said lm being formed from a vinyl resin. i

5. A printing stencil comprising a foraminous screen and a film cemented thereto, the film having openings therein corresponding to a design to be reproduced, said screen being formed from material selected from a class consisting. of vinyl resin, acrylate resins, land polyamine-polybasic acid resins, said film being formed from ethyl cellulose.

6. A printing stencil comprising a foraminous screen and a film cemented thereto, the filmhaving openings therein corresponding to a design to be reproduced, said screen being formed from a vinyl resin spun into a fabric, said film being formed from material comprising ethyl cellulose having mixed therewith xylol, butyl acetate, butanol and a plasticizer.

7. A printing stencil comprising a foraminous screen and a film cemented thereto, the film having openings therein corresponding to a design to be reproduced, said screen being formed from a synthetic fibre which is alkali resistant, the film being formed from a composition containing 3 parts sperm oil, 1 part hydrogenated methyl abietate, and 50 parts of a solution containing` the following:

' Parts `Ethyl cellulose (low viscosity) 36 Xylol 80 Butyl acetate Butanol 15 including a mixture of toluol, ethyl acetate and butyl acetate.

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