US1935629A - Lithographic ink - Google Patents

Description

Patented Nov. 21, 1933 uN rsn srarss ,:L ITHOGR'APHIC INK l John 1G. 'Goedike, San AntonimTex.

No Drawing.

7 Claims.

Application November 28, 1931 Serial No. 577,867

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 O. G. 757) This invention described-herein may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

This invention relates to an ink especially adapted for use in making prints from lithographic and analogous printing presses and more particularly it is directed to the ingredients of an ink for use in connection with plate cylinders gm which are chilled to a temperature substantially below the dew point of the normally surrounding atmosphere of the press on which the. plate is mounted.

Heretofore the inks used in making impressions from the plate cylinders of lithographic and analogous presses especially those plate cylinders which have been cooled and on which warm moist air or steam is caused to come in contact with the cool plate for dampening purposes had such substances as stearic acid, tallow, gum

mastic, parafiine and beeswax added to the ink to increase the greasy nature and stiifness thereof.

To prevent scumming of the plate due to abrasions of the desensitized blank spaces thereon,

fountain of the presses heretofore used.

It has been found that an ink composition of greatly improved qualities may be made by substituting wool fat and gum-arabic for the sub- 31 stances mentioned above.

If the ink made in accordance with my invention is applied to a plate cylinder which has been dampened by chilling the plate to a temperature substantially below the dew point of the normally 5 surrounding atmosphere of the plate an impression may be obtained therefrom, which is a great improvement over the impressions heretofore obtained from lithographic and analogous plates and the production of inks with greater color {41 strength and much softer in consistency will result from the substitution of the substances above mentioned. My improved ink is well adapted to work on a chilled surface, and eliminates scumming and false tinting of the plate- .45 which is quite common and troublesome in obtaining impressions from planographic and analogous plates with inks containing the substances heretofore used.

The ingredients of which my ink is composed are as follows: I preferably use a mixture of plate oil and wool fat which are triturated in the proper proportions with a dry color pigment ground therein. To this mixture is added an emulsion of gum-arabic which is obtained by dissolving the gum-arable in water and charging a weak etching solution is used in the water with chromic acid for inks of blacks and yellows, gallic or other suitable acids being used for light colored inks. The gum-arabic solution or dispersion with the chromic or gallic acid is triturated with a heavy lithographic varnish and a small amount of glycerine is added thereto.

The plate oil is made by burning linseed oil which is the base of lithographic varnish with hot irons which are immersed therein until the oil has lost some of the greasy characteristics thereof which are troublesome in lithographic printing The wool fat is used because it has a low setting point working well at low temperatures without crumbling and supplies the necessary greasy nature to the ink and also keeps the design on the lithographic plate from wearing while by incorporating the gum-arabic and chromic or gallic acid in an emulsion with the heavy lithographic varnish such as No. 3 or heavier and'grinding with the color pigment scumming and false tinting of the planograph or analogous printing plates are eliminated. a

The relative proportion of the constituents of the composition to be used in thejmanufacture of (so the improved ink for use with coldlithographic or analogous printing plates may vary within rather wide limits. The following examples illustrate proportions which I have found to be' effective:

For blue ink: I preferably use 35 lbs. of blue pigment (milori blue), 18 lbs. of plate oil, 1 1b. of wool fat and 3 lbs. of the gum-arabic emulsion.

Forred ink: 50 lbs. of red pigment (litho red) gm 45 lbs. of a light form of lithographic varnish such as is known in the art as No. 1 lithographic varnish, 1 lb. ofwool fat and 3 lbs. of gum-arabic emulsion. p

For yellow ink: 57 lbs. of yellow pigment (lemon yellow), 21 lbs. of No. 1 lithographic varnish, 1 lb. of wool fat and elbs. of gum-arable emulsion.

Gum-arabic emulsion is obtained by dissolving 5 lbs. of gum-arabic in 1 gallon of water and 1 mixing with equal parts by weight of No. 3 lithographic varnish. The gum-arabic emulsion used in making the yellow ink requires the addition of one ounce of chromic acid just before the mixture is triturated for grinding.-

Having described my invention what I claim as new and useful is: V

1. A composition of matter for printing ink, comprising plate oil, wool fat, an aqueous dispersion of gum-arabic and a pigment.

2. A composition of matter for printing ink, comprising plate oil, wool fat, an aqueous emulsion of gum-arabic and a pigment, said aqueous emulsion containing lithographic varnish.

3. A composition of matter for printing ink, comprising plate oil, Wool fat, an aqueous emulsion of gum-arabic and a pigment, said aqueous emulsion containing lithographic varnish and an acid.

4. A composition of matter for printing ink,

comprising plate oil, wool fat, an aqueous emulsion of gum-arabic and a pigment, said aqueous emulsion containing lithographic varnish, glycerine, and an acid.