US2820710A - Printing inks - Google Patents

Description

United States Patent iiice PRINTING INKS No Drawing. Application December 1, 1953 Serial No. 395,584

8 Claims. (Cl. 106-26) This invention relates to printing inks and more particularly to printing inks of the type designed to permit rapid drying or setting of the printed impression by the application of heat, steam, liquid water, or a combination thereof.

Modern printing methods, and especially the operation of high speed rotary, web-fed presses, require that the ink be rapidly dried and bound to the paper so that the paper may be immediately printed on the reverse side with no transfer of ink to the guide bars, guide rollers, or second side impression cylinders of the press.

In order to meet these requirements, it has previously been proposed to include volatile solvents in the printing ink and quickly vaporize the solvent following printing by the application of heat to the freshly printed web, leaving the ink substantially dry and bound to the paper.

A difliculty heretofore experienced with inks of that type is that where too volatile a solvent is used, the ink tende to dry prematurely on the ink distributing rollers and printing plates, resulting in the paper web being picked or ripped by adhering to the tacky, partially dried ink on the printing surfaces. On the other hand, if a solvent of low volatility is used, excessive drying temperatures are required in order to obtain the desired rapid rate of drying.

In order to avoid the necessity of using a solvent of too high volatility, and yet obtain the desired printing speed in processes of this type, it has usually been necessary to effect the drying by subjecting the printed matter to such high temperatures as tend to weaken the paper, usually of the order of 300 to 700 F., and frequently leads to interruption of the press-operation due to the breaking of the web. Such operations are also costly because of the large amount of fuel required for heating the web to those high temperatures.

Further difficulties encountered in the selection of a solvent of suitable volatility have been the tendency of some vehicles to produce inks which permit too great a penetration of the ink into the paper, or which have poor transfer properties with respect to the inking mechanism or to the printing surfaces or to the web, or which fly off from the rapidly rotating cylinders by centrifugal action, or in which the dried ink film tends to rub or send off the printed matter.

It has more recently been proposed to set the ink on the printed matter by the application of steam, superheated steam, or even liquid water. However, the inks now being used in the art which set by the application of steam, the so-called steam-set inks, cannot be used with half-tone plates for long runs without causing specking or fill-up and thus printing results of unsatisfactory quality.

It is an object of our present invention to provide inks having a nitrocellulose base and which are press stable, i. e., will not dry prematurely on the inking mechanism and printing plates, but which can be rapidly dried at substantially lower temperatures than those currently required with presently available inks.

I set inks.

properties, and has good flow characteristics and excellent 2 A further object is to provide inks which may be dried or set by application of either heat, steam, superheated steam, or liquid water, or a combination thereof, to give satisfactory prints, with no specking or fill-up when used with half-tone plates.

A further object is to provide inks having, in addition to the properties just noted, superior transfer properties and a lower penetration into the paper than the inks currently used, and by which the pigment is bound more i firmly'to the paper and willnot rub or scuff off. A still further object is to provide an ink of the type described which, at high printing speeds, will cohere and adhere to the rapidly rotating surfaces with less flying, or misting, than currently available inks of this type.

These and other objects are attained by our present ever, nitrocellulose of the type previously proposed is not soluble in the alkanediols used in accordance with our present invention and is unsuited to our present purpose.

We have discovered, however, that nitrocellulose of the alcohol-soluble type, just noted, which has been nitrated to an extent not exceeding 11.7%, e. g., l0.7-l1.7%, is

readily soluble in these alkanediols, either with or without heating, and provides an ink vehicle which, when compounded with suitable coloring matter, results in an ink which is amenable to rapid drying or setting of the printed impression either by the application of heat, steam, superheated steam, liquid water, or a combination of'these drying and setting methods, and which avoids the previously noted difficulties experienced with steam- The resultant ink also has excellent transfer printing properties in all other respects. Further, the resultant ink has good press stability, that is, it does not dry prematurely on the press. Nevertheless, the printed imabout Mi second. However, nitrocelluloses of this type,

having a viscosity of /2 second, 5-6 seconds and 40-60 seconds have also been found to be soluble in the alkanediols previously noted and may be used, with advantage, in accordance with our present invention. The viscosity of the nitrocellulose does not appear to be critical so long as the particular nitrocellulose is soluble in the alkanediol or mixture of the alkanediols used.

The proportion of nitrocellulose used is also subject to considerable variation, depending upon the desired characteristics of the ink. Generally satisfactory results may be obtained using proportions of nitrocellulose within the range of 2% to 25%, based on the weight of the ink. Especially advantageous results have been obtained where the proportion of nitrocellulose is within the range of 2% to 10% by weight of the ink.

diol or 2-ethyl-l,3-hexand iol, or Z-methyI-ZA- entandiol.

We have found the 2 methyl-2,4-pentandiol particularly advantageous for this purpose. However, other alkane- Petented Jan. 21, 1958 v diols having not more than 8 carbon atoms, ,0]: mixtures...

ties and jthat the inks'resulting from incorporating pig-- ments, or other coloring material, therewith? gives excela lent results in printing with half tone plates. overzlongrv runs without causing specking or fill-up, regardless Did.

the particular method usedin drying: or. setting themk 'Where desired, the nitrocellulose filmmay 'bev modified by including in the ink asubstantial proportion of. a:high

boiling material of the'type'known to. the art5for their,

ability to modify such films., For instance, we may. in;-

corporate in theink substantial proportions; of "dioctyl phthalate, tricresylphosphate, castor. oil, ,camphor, di-' butylsebacate, orother esters, ethers; ether-esters-orre lated materials.

We have, with particular, advantage; incorporated .in the ink for this purpose a substantial proportion, of the, order 0f5 to based on-the weight of the ink, ofxa' mixture of high molecular weight alcohols, ethers, and. esters, the alcohols of the mixture containing :8 :orgmore carbon atoms per molecule and-the esters and ethersrof' the mixture'containing 16 or more carbon-atoms pen molecule,.the mixture boiling within'the rangeof-about 210 to-360. C. Such mixture of high boiling alcohols, ethers and esters have been used, with particularadvanrage, in. conjunctiontwith nitrocellulose" of- Mr second viscosity, and: of 10.7% to l1.'2%..nitrogen,content; and" 2-methyl-.2,4v-pentandiol as the'alkanediol solvent-.1

The invention will be further illustrated by the:follo.W-' ing specific examples. It*will be understood, however; that. these examples areby-way of illustration :and .are not intended to be limitative;

Example I A vwet-process. Peacock. Blue inkzhas been prepared-,1. as hereinafter described, from the followingingredients and proportions thereof:

Parts A second nitrocelluloset 1012-1 1.2%. nitrogen) 2-methyl2,4.-pentandiol t .5 8:1 Pigment, 36.5.

cous fluid results; The solution of ith'e" nitrocellulose" mayibe aided by heating, -where desired," but *usuallyjheating:.isnot necessary. Following-solutionof the =nitro= cellulose, .the pigment may be added" and mixedwith thevehicle; as by stiriingin' a conventional mixingdevicew The resultant mass is then passed over anink'mill untila smooththomogeneous' ink results.

was'crin'corporated :is illustrated by the following vexample f of a Wet-process channel black' inkfi The, compounding of'the" .severalifigredieirtsmay be efie'cted "as. previously, described; the tricresylphosp'hate being added with the-:alk'zinedidl;

WHere desired, other-resins, -solub1e- -inthe-airman;

or mixture of lthese-all2nediols may alsobe-in'cludedin the-inltf as illustrated lay/the. following examples;

4 Example III.

A wet-process chrome yellow ink has been prepared from the following ingredients in proportions thereof:

Parts M4 second nitrocellulose (10.7.-"1'1.2% nitrogen) 4.0 Zein 5.0 2,3-butylene glycol 30.5 2-methyl- 2,4.epentandiol 2515 Pigment 3510 Example IV A weteprocessPhloxine;Red. ink has-been prepared from the following ingredientszand. proportions thereof:

- Parts A, second nitrocellulose (l0.7l1.2% nitrogen) 4.4 A rosin-maleic adduct 9.6 2-methyl-2,4-.p entandiol 35.5 l,5-pentandiol" 2115 Pigments 29.5

Example V A particularly advantageous .inkv inwhich the, nitrocellulose film is. modifiedsby, the-inclusion in. the ink. of

a mixture. ot-high.moleculanweight alcohols, ethers, and esters, .of the. .type, previously. described: herein, has. been. prepared as .follows, I

Bynthe procedure previously described,..-an inkvarnish was prepared.from.therfollowingjngredients and the .PI'O'}, portions. thereof:

Parts.-v second,nitrocellulose (10. Z-11.2% nitrogen), 33 Alcohol-ethereester.mixture: 13

Z-methyl-ZA-pentandiola 53 To. the :foregoing'yarnish; the pigment" and additional alkanediol were addech'irr accordance withpthe following formula:

Parts Above varnish 23 Z-methyl-ZA-pentandibl 42" Pigment and pigment extender 35' As the pigmentextender, wenmaygforv instance-use, calcium carbonate;., China .clay, blanc .fixe or-i thexlilcex Where.desired,thelpigmentmaybe usedwithout extender.

The invention is not restricted as tothe typeiof pigment depending on the properties of :the ink desired, such ;as

shade, viscosity, gloss, tinting strength, and the like, as:

is understood by-the art; Where vsdesired, .the ethanol.. added with the nitrocellulose may be eliminated'during the compounding of theQinlgz-for instance,.by sol-vent in terchange. However, its presence .in. the .lfinisheddnkz is:

not usually objectionable;

Weclaim: 1. A printing ink. comprising a: coloring consisting I of 1,2-propanediol; 2-methyl-l,2=propanediol; 1,5.-pentandiol,' I tandiol and :2,3 -'butylene glycol, the proportron zof mtro cellulose being within theirarrgez of ;-from::ab'out..2% torn I 25 basedzon the weights of :theainkr 2. The printing ink .otclaimsl in whichxth'e nitrocele Where a yellow i coloredninle is required,

:material dis-: persed in a vehicle=consistingessentially:of nitrocellulosei. of the alcohol-solublewtype :containing not: more'tl1an1 11.7% nitrogen, dissolved in an alkanediol from the groupu" 5 lulose is of Ms second viscosity having a nitrogen content within the range 10.7% to 11.2%.

3. The printing ink of claim 2 in which the nitrocellulose is present to the extent of 2% to 10% by weight of the ink.

4. The printing ink of claim 3 in which the alkanediol is Z-rnethyl-Z,4-pentandiol.

5. The printing ink of claim 4 in which there is also incorporated a substantial proportion of a mixture of high molecular weight alcohols, esters and ethers, the alcohols containing at least 8 carbon atoms per molecule and the esters and ethers containing at least 16 carbon atoms per molecule the mixture boiling within the range of 210360 C.

6. The printing ink of claim 1 in which there is also incorporated a substantial proportion of a mixture of high molecular weight alcohols, esters and ethers, the alcohols containing at least 8 carbon atoms per molecule and the esters and ethers containing at least 16 carbon atoms per molecule the mixture boiling within the range of 2l0360 C.

7. The printing ink of claim 1 in which there is also incorporated a resinous material soluble in the a1kane diol.

8. The printing ink of claim 1 in which there is also incorporated a high-boiling film-modifier for the nitrocellulose.

References Cited in the file of this patent UNITED STATES PATENTS 2,070,218 Kelly Feb. 9, 1937 2,437,908v Chiappe Mar. 16, 1948 2,537,531 Hoyt Ian. 9, 1951 OTHER REFERENCES

Claims (1)

1. A PRINTING INK COMPRISING A COLORING MATERIAL DISPERSED IN A VEHICLE CONSISTING ESSENTIALLY OF NITROCELLULOSE OF THE ALCOHOL-SOLUBLE TYPE CONTAINING NOT MORE THAN 11.7% NITROGEN, DISSOLVED IN AN ALKANEDIOL FROM THE GROUP CONSISTING OF 1,2-PROPANEDIOL, 2-METHYL-1,2-PROPANEDIOL, 1,5-PENTANDIOL, 2-ETHYL-1,3-HEXANDIOL, 2-METHYL-2,4-PENTANDIOL AND 2,3-BUTYLENE GLYCOL, THE PROPORTION OF NITROCELLULOSE BEING WITHIN THE RANGE OF FROM ABOUT 2% TO 25%, BASED ON THE WEIGHT OF THE INK.