US2285430A - Lithographic ink - Google Patents

Description

Patented June 9, 1942 UNITED, STATES PATENT OFFIJICEI urnocmrmc m1:

' Albert E. Gesslcr, New York, N.

Gal-man, Dumont, Nil, and Louis ieal Corporation, blew Rockville Centre, N

tion of Ohio No Drawing.

Serial No. 4 Claims. (Cl. 106-32) 'tion and polymerization. It is customary to accelerate the setting by heating from 200-300 F., but, even under these circumstances, a period of from 20 to 30 minutes is required to set the ink. This requires bulky furnaces and mechanism for stacking ,the printed metal sheets in the furnaces and precludes the possibility of web printmg. I

While there has long been a demand for a quick-drying lithographic ink which would i do away with the delay and inconveniences of the' present method, it has heretofore proved impossible to provide an ink of reasonable cost which would meet the numerous physical requirements for an ink satisfactory for lithographic set printing without introducing substantial q antities of drying oils which cannot be set ratpidly. By our invention, we have, we believe for the first time, produced an ink which meets all the requirements of lithographic printing and which also has the ability to stand very high temperatures without injury and to set almost ina plasticizer a when exposed to high temperatures, such as into containers.

is also water-repellant. It may be a vegetable or repellant and shows stantaneously at such temperatures. The use of this ink entirely does away with the the cumbersome furnaces now used with lithographic printing on metal, and makes it possible to substitute a furnace of small dimensions heated to a high temperature through which the sheets may be passed horizontally, for the time of heating required is reduced from a period of 20 to minutes to a matter of 2 or 3 seconds. Furthermore, the use of our ink permits passing the sheet metal through the press necessity of,

and also through the furnace in web form, thus facilitating the handling of the metal in speeding up the process. a I

A lithographic ink embodying our invention has a vehicle consisting of a water-repellant.

natural or synthetic resin dissolved in a volatilizable solvent consisting of parafiin hydrocarbons substantially free from unsaturated and aromatic constituents. The vapor pressure of the solvent is such that it is substantially non-volatile at room temperatures, while it evaporates in connection Y., Everett F.

F. Engelhart,

assig'nors to Interche j York, N. Y., a corpora- Application June 30, 1937,

with great rapidity peratures such as 1000-2000 F.

A further feature particularly important in metal printing, consists .inplasticizing the resin of such an ink by which is substantially non-volatile l0002000 F., so that, after the ink has been exposed to such temperatures to evaporate the.

solvent; the plasticized resin remains uninjured and gives the ink film sufiicient plasticity to avoid cracking when the printed metal is made up An 'ink embodying our invention has all the physical and chemical properties necessary for good ofiset lithographic printing,

In the first place, it has no tendency to emulsify with the water or on lithographic presses. Theresin used as a binder is a water-repellant substance such as a rosin ester, a polymerized hydrocarbon, a modified alkyd resin, a phenolic resin, a damarresin, or the like. The plasticizer used with the resin animal oil, such as .peanut, soya, linseed, corn and fish oil, or an ester, such as methyl abietate,

tricresyl phosphate; or plastic synthetic resins,

such as-oil-modified alkyds, may be used. The solvent, consisting of paraflin hydrocarbons, is also water-resistant.

forming the vehicle of the ink is highly waterno. tendency to emulsify either with water alone orwith the various conventional fountain liquids which include various dilute solutions of water-soluble substances. In the next place, the ink is stable on the press and maintains the proper consistency for good oifset lithographic portioning of the resin to the solvent, the desired stifi consistency of the present linseed 'oil lithographic inks can easily be obtained. The maintaining of this consistency on the press over long periods-is the result of several factors. One is the high boiling point of the solvent whi'ch renders it substantially non-volatile at ordinary room temperatures (GO- F.). This result is attained by using a hydrocarbon mixture not more volatile than is indicated by a 5% distillation at 200 C. and a distillation at220 C.

I This factor alone, however, is secure the required stability of consistency. The chemical composition of the vehicle is also of great importance, for the ink must be spread out 55 on inking rollers on the press when exposed. to high temof the invention, which is.

usual fountain liquids used The result of this selection of the binder and solvent is that the solution printing.- By proper not sufficient to and then offset from the printing member to a blanket. In the past;rollers and blankets were made almost entirely of rubber; but the oils in ordinary lithographic inks have an appreciable swelling action on rubber, so that rubber rollers and blankets have a rather short life. Rubber rollers have been almost entirely replaced by composition rollers, made of polymerized oils, which are much more resistant to oil swelling; while compositions have been introduced for the blankets '(such as compositions made with Thiokol, a plastic made .by treatment of halogenated olefines with polysulfides) which are much more enduring than rubber blankets. We have found that if the ink has any tendency to react with, absorb, or to be absorbed by, these materials, used in the usual rollers'and blankets of a lithographic'press, it will fail to give proper printing over long periods and be of no practicalvalue. These difficultiessoluble in the dimethyl sulphate being the dimethyl sulphate value). A dimethyl sulphate value exceeding 4.0 or 5.0 indicates that a hydrocarbon-mixture is unsuitable for use in our ink. Small amounts of certain additions may be included in such solvents, provided they do not substantially increase the swelling action of the mixture on the rollers; thus, we have found that certain higher alcohols, e. g. lauryl alcohol, can be used in amounts up to a very few percent., without increasing the solvent action of the hydrocarbons.

In addition to meeting the requirements fo ofiset lithographic printing, our ink has the ability to stand very high temperatures without injury and to set substantially instantaneously at such temperatures. To insure instantaneous setting, we use a hydrocarbon mixture which is completely volatilized at a temperature not exceeding 400 C. Substantially instantaneous volatilization of such solvents may be obtained by exposing the prints to temperatures of the order of 1000-2000 F. for a period of a few sec- EXAMPLE 1.-Clear lithographic va mish Ester gum (rosin, substantially completely esterified with glycerol) 4 Oil modified alkyd resin (Duraplex C 45 L. V.--R.esinous Products Co.) 11.4 Parafiin hydrocarbons (272-311 C1) 38.2

(The boiling range of all of our hydrocarbons is shown from 5% distillation to 95% distillation.) This clear varnish is intended for'use in overprinting an ink lithographically, to protect the print and increase the gloss. The formula is especially intended for tin printing, as sufficient alkyd resin plasticizer is present to permit of forming after drying.

, EXAMPLE 2.Red ink Lithol r d Ester gum 34.3 Oil modified alkyd (Rezyl 869-American Cyanamid) 7.8 Paraifin hydrocarbons (272 -311 C.) 22.8 Similar to above, for tin decorating.

E AMPLES 3.-Red ink Barium lithol toner 35.0 Ester gum 39.0 Peanut oil (plasticizer for tin forming-h"- 7.8 Paraifin hydrocarbons (B. P. 263-297 C.) 18.2

EXAMPLE l -Yellow ink Chrome yellow 55.1 Hausa yellow 3.6 Aluminum hydrate 7.4 Varnish 33.9 Phenolic resin (Amberol S' I-l37 'Resinous' Products Co.) 53.0 Oil modified alkyd resin (Glyptal 2464- G'. E.) 12x0 Paraifin hydrocarbon (283*326 C.) 35.0

EXAMrLu 5.-Bl'ue ink Iron l 40. Varnish 60 Modified maleic' anhydride resin (Paranol 89-Paramet Chemical Co.) 57.0 Peanut oil 12.0

Paraffin hydrocarbon (B. P. 272-311 C.) 31.0

onds. In such treatment, the prints do not-reach the temperatures of the oven; the print temperatures. probably never go above 300 C. The non-volatility of the plasticizer at these tem-v peratures prevents the intense heat from' injuring the ink and leaves the resin adequately plasticized after such temperatures have been used to evaporate the solvent.

In its preferred form, our ink is capable, after setting, of adhering to metal sheets without cracking when these sheets are bent to form them into containers. This result is obtainedby use with the resin of a water-resistant,-non-volatile plasticizer in a quantity sufiicient to give the plasticized resin a plasticity of at least .026 centimeters, using a standard A. S. T. M. penetrometer with a standard needle and a 200 gram weight acting on the needle for 60 seconds at 25 C.

The following art typical examples of inks made in accordance with our invention:

EXAMPLE 6.White ink The method of application of these inks is substantially similar to the method of applying the old type lithographic inks; and they may be dried by the old methods. When run through a regular tin-lithographing set-up, our inks will dry in from 3 to 5. minutes, as compared to a 20 to 30 minute drying schedule for the old type inks.

With prints of our inks, almost instantaneous 2,285,430 may be obtained by evaporating the solvent, by exposing the printed surfaces to extremely high temperatures, of the order of 1000-2000" F., it being possible under such conditions to obtain complete drying in a time as short as from one to two seconds, as compared with a minimum of 20 minutesfor the'ordinary type of lithographic ink. It is possible to obtain complete drying in a continuous oven only 6 feet long, as compared with an 80 foot oven required for old style drying, even when accompanied by racking of the sheets. Thus it is possible to save both space and the labor required for rackingand unracking.

Web printing of lithographic inks hasv been heretofore attempted on absorbent paper stock; even with absorbent paper, smudging and set-oft occur because the ink is only partly absorbed and- It has been im not really dry on the sheet. possibleto print webs of fully sized paper, metal or non-absorbent stock from lithographic plates with inks heretofore available. Still another advantage of our inks is the fact that they can be dried sufiiciently rapidly to permit of such web printing, either on paper or metal, without smudging or set-ofi.

Where a combustible material is printed with our inks, the heat necessary fordrying should preferably be supplied to the paper by burnerssituated above the printed side of' the paper. Direct flame ribbon burners or radiant heat burners may be employed. In this case, the paper itself will not attain a temperature suificientto cause scorching, if proper precautions are taken as to web speed. With non-combustible materials, the heat may be appliedin any convenient manner. The solvent may-,bemerelyevaporated,

or it may be burned during the evaporation to 3 insure a more complete removal of solvent.

The term lithography, as used throughout the specification and claims, is the term as commonly used in the printing trade; it includes any offset printing from planographic plates, whether stone or metal, flat orcurved.

We claim:

'1. A lithographic printinginkcomprising pig- -ment dispersed in a vehicle comprising a solvent consisting essentially of a petroleum fraction with a dimethyl sulfate value less than 4.0, which fraction is substantially non-volatile at about 90 F., but evaporates rapidly when exposed to a temperature of 1000 -2 000 Efor a few seconds, andsufilcient resin in said solvent to give. the consistency: of ordinary lithographic printing mks r 2. A lithographic printing ink comprising 'pigment dispersed in a vehicle comprising a solvent consisting essentially of a petroleum fraction with a dimethyl sulfate value less than 1.0, which fraction is substantially non-volatile at about 90 F., but evaporates rapidly when exposed to a temperature of 1000-2000 F. for a few seconds, and sufiicient resin in said solve'ntto give the consistency of ordinary lithographic printing tion of a plasticizer-which does not evaporate,-

when exposed to a temperature of 1000-.2000 F.

for a few seconds and which givesthe resin a plasticity of at least .026 centimeters as measured on a standard A. S. T.- M. penetrometer at 25 0., using a standard n'edle,'a 200 gram weight and seconds time. ALBERT E. GESSLER. LOUIS F. ENGELI-IART. EVERETT F. CARMAN.