US2225736A - Printing plate with smudgeproof edges - Google Patents

Description

Dec. 24, 1940.

w. J. CHAMPION ET AL PRINTING PLATE WITH SMUDGEPROOF EDGES Filed Feb. 28, 1938 ,very apt to receive grease impressions.

during the subsequent Patented Dec. 24, 1940 UNITED STATES PATENT OFFICE William J. Champion, La Grange, and Johan Bjorksten, Chicago,

corporated, Chicago, Virginia Application February as, 1938, Serial No. 193,088

2 Claims.

This invention relates to printing plates, and

more particularly to thin, flexible,

planographic in its dry state, however, is receptive to oil inks and to other oily or greasy materials applied by pressure. Therefore, when the planographic plate is handled, as ,by placing it in or removing it from the typewriter, the edges of grease impressions remain moistening and inking of the plat the plate are These e. Being repellent to water and oil ink absorbent they become inked. Thus copies made from the plates show ink impressions of the grease prints and have an unattractive appearance.

An object of this invention is to provide a A printing plate, the edges of which can be touched freely with hands and greasy materials without danger of smudging.

Other objects and advantages of the invention will become apparent as the following detailed description progresses, reference being had to the accompanying drawing, in which Fig. 1 is a perspective view of the planograph plate embodying the invention.

Fig. 2 is a sectional view of the plate of Fig. 1

taken along line 2-2.

Fig. 3 is a perspective view of a modified form of planograph plate which constitutes another embodiment of the invention.

Referring to Figs. 1 and 2 wherei form of the invention is embodied,

n a preferred the reference character I designates generally a printing plate which is smudge proofed along its gins with a material will not remain on it during the lateral marwhich is grease repellent, at least to the extent that grease-impressions,

operation of to the print- In Fig. 4 another embodiment, of the invention is illustrated in which has similar grease repellent coatings all of the edges thereof.

a printing plate la 2a along for 2a may be attained by the application of a reagent which forms a water soluble or hydrophilic combination with the material of the printingplate or which covers it with a water solubl of a hydrophile colloidal nature.

e film or film a thin flexible aluminum 111., assignors to Ditto, 1n-

Ill., a corporation of West In a preferred embodiment ofthe invention a thin flexible 8 x 11" aluminum plate is coated with an aqueous solution of sodium silicate along the margin so as to form a protective film extending toward the center of the plate for about 5 inch from the outer edge-of the plate.

In another embodiment of the invention a thin zinc plate is given a margin coating of dilute sulphuric acid. This sulphuric acid reacts with the zinc surface to form a film of zinc 1o sulphate, which is water absorbent and grease iepellent in the normal hydrated condition.

Marginal protective coatings on zinc or alurninum may also be made by applying solutions I of nitric acid,-phosphoric acid, sodium hydroxide, is triethanol amine, monopotassium phosphate, trisodium phosphate or sodium carbonate. Evap-, oration of the solvent by means known to the art will leave a very thin protective coating of a water soluble or hydrophilic nature.

Likewise, gum arabic, gelatin, casein and other water absorbent, grease repellent colloids may be used to form a protective smudgeproof margin on metallic or other type of printing plates. Such colloidal substances may be used alone or in combination with any of the above mentioned materials.

Usually, we prefer to apply these materials in 5 to 10% solution but wide variations are permissible in this regard.

While the preferred embodiment of the invention has been shown and described, it is to be understood that it' is capable of many modifications. Changes, therefore, in the construction and arrangement may be made without departing from the spirit and scope of the invention as disclosed in the appended claims in which it is the intention to claim all novelty inherent in the invention as broadly as possible in view of the prior art. to

We claim: I

1. A thin flexible printing plate, adapted to be placed in a typewriter, having a smudgeproof marginal coating comprising sodium silicate, the entire non-marginal portion being normally oil- 4.) ink receptive.

2. A planographic printing plate comprising sheet having a margin protected with a thin adhering layer of sodium silicate, the entire non-marginal portion be- 5:) ing normally oil-ink receptive.

WILLIAM J. CHAMPION.-

JOHAN BJORKSTEN.

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