US2372355A - Hectograph blanket - Google Patents

Description

Patented Mar. 27, 1945 niac'roenlirn BLANKET William J. Champion, La Grange, 111., asslgnor to Ditto, Incorporated, Chicago, lll., a corporation of West Vll'glnla Nd Drawing. Application February 10, 1943, Serial No. 475,452

1 Claim.

The invention relates to hectograph duplication blankets, and particularly to blankets adapted to be rolled up in the form of rolls, and to the methods of duplication using such blankets.

Hectograph blankets commonly comprise a copy mass consisting substantially of glue, glycerin and water attached-to a flexible backing. The flexible backing is generally paper or cloth which has been impregnated with a composition such as glue and glycerin which is dried and then lacquered with a suitable lacquer such as a nitrocellulose lacquer. A layer of a bonding agent such as linseed oil or other drying oil may also be coated on one side of the lacquered backing in order to more firmly secure the copy mass to the backing. The copy composition which commonly consists of glue, lycerin and water which will set to a firm gel, is coated over the bonding layer and allowed to gel. The hectograph blanket is generally made in the form of a long strip which may be rolled into a roll and used in a hectograph duplicating machine. The roll is then unwound for duplication, and after copies have been made the roll is again wound up, and. at this time the unused dye area. on the copy mass contacts the dye absorbent backing and the copy mass is cleared for re-use.

However, the image of the copying area is transferred faithfully to the backing material and remains quite legible indefinitely. This is very objectionable when the nature of the material being copied is of secret nature such as, for example, military maps, plans, etc., which are often copied at the scene of battle.

The principal object of this invention is to provide a hectograph blanket having a backing which will bring about complete obscurity of the latent image which is transferred thereto when the blanket is rolled after use.

Another object of the invention is to prepare a hectograph roll which has improved appearance and which will not show transferred dye smudges from the fingers of the operator.

Other objects and advantages of the invention will become apparent as the following detailed description progresses.

In accordance with one embodiment of this invention, the copy mass is secured to a colored backing having a color intensity such as to hide the duplicating characters which may be transferred to the backing during use of the blanket.

The backing may be colored by incorporating in the impregnating composition or the lacquer a color agent such as a colored pigment or a dye of substantially the same color and intensity as the duplicating ink which is being used for the copies. Preferably a water and alcohol soluble dye of the same color as the copying ink is used to color the backing, thus giving complete obscurity when the copy characters are transferred to the backing.

A colored backing may also be obtained by using a colored paper which is impregnated and coated with transparent compositions, the color of the paper itself serving to mask any images transferred to the backing.

In a hectograph roll which is adapted for use in a hectograph duplicating machine the backing extends beyond the copy mass and is called a leader. Since at least a portion of the leader is in contact with an underlying copy mass when the hectograph blanket is wound up into a roll the leader should be colored and have a color intensity about equal to the color intensity of hectograph dye characters. Preferably the leader is lacquered like the remainder of the backing and the dye or color pigment may be incorporated in, the lacquer.

The following example is given to illustrate the invention and aid in the explanation, it being understood that the invention is not limited to, the specific details given in the example:

Cotton cloth or a high wet strength paper is impregnated with a, composition consisting essentially of glue 9 parts by weight, glycerin 682 parts by weight, and water 22.3 parts by weight. The impregnating composition is heated to a temperature of about 140 F., and a strip or web of paper is immersed in the composition for a period of from 1 to 3 minutes, after which it is dried. The impregnated backing is then coated on both sides with a lacquer of the following composition:

- Per cent by weight Half second nitro cotton 15 Castor oil 17% Dibutyl phthalate 4.5 Ethyl aceta 61 10% solution of methyl violet 2 This lacquer was coated on the backing at a temperature of from to F. and dried.

One side of the lacquered and impregnated backing was then coated with linseed oil.

On the linseed oil coating a hectograph composition of the following formula was applied:

The above composition was allowed to cool, forming the hectograph copy mass which was firmly secured to the backing. The backing due to the dye in the lacquer was of suflicient color 2 aavaau intensity to mask duplicating characters formed or any hectograph duplicating dye so that when the hectograph blanket was used for making copies and rolled after use no characters were visible on the hectograph blanket after unrolling and examination.

While I have made reference to specific embodiments by way of illustration, I fully realize that the invention is'capable of wide .variations in the selection of the various agents employed and in their proportions; and such variations, therefore, do not involve any departure from the spirit or scope of this invention.

10 stantially invisible!" WILLIAM J. CHAMPION.