US3029154A - Method of printing on paper and resultant article - Google Patents

Description

United States Patent Ofiice 3,029,154 Patented Apr. 10, 1962 3,029,154 METHGD F PRINTING 0N PAPER AND RESULTANT ARTICLE Ales Maria Kapral, Kingstord, near Sydney, New South Wales, Australia, assignor to Process Methods Corporation, Chicago, Ill., a corporation of Hlinois No Drawing. Filed Mar. 29, 1957, Ser. No. 649,276 Claims priority, application Australia Feb. 1, 1957 30 Claims. (Cl. 117-15) This invention relates to the art of printing, and it is concerned principally with the printing of newspapers and books, although it is applicable to any other printed matter. The invention can be used genrally, for all methods of printing, for instance by letterpress, rotary press, lithography, Linotype and in all other methods involving the transfer of printing ink onto a paper, board or similar surface, although in the following description reference will be made to paper only, for the sake of simplicity.

One object of the invention is to provide a method of printing by the use of which the depth of penetration of the paper by the printing ink is reduced whereby an improved quality of the print and an increased drying rate of the printing ink is achieved.

The reduction in the depth of penetration by the printing ink leads to a reduced consumption of ink and therefore to an increased economy of the printing process.

A further effect achieved according to the invention by the reduction in the depth of ink penetration is that the thickness of the paper required for achieving sufficient opacity to enable both sides of the paper to be printed, is reduced as well which, in turn, can lead to increased economy in the amount of paper pul required for the production, for instance of newsprint.

During a study of the drying time of different printing inks used in high-speed rotary processes, and of the penetration of solvents contained in printing inks into the fibres of paper, it was observed that a porous surface coated with a thin continuous layer of one or more of certain metallic salts of higher fatty acids such as for instance stearates, resinates, oleates, linoleates and naphthanates of such metals as manganese, zinc, iron, nickel, aluminium, cobalt, chromium, magnesium and copper, have a high affinity for printing ink, provided these metallic salts are unmixed with or do not contain any excessive quantities of incompatible ingredients such as clay or other fillers, and provided further that the printing ink contains a solvent of the metallic salt or salts forming the layer such as, for instance, vegetable or mineral oils, oxidised oils and hydrocarbons.

It was also found that the solvent content of the ink penetrates into the paper which, when coated as stated above, is usually water-repellent, and dissolves some of the metallic salt coating. As a result of such dissolution the solvent of the ink is thickened and its further penetration into the paper is impeded, such penetration being further increased owing to the drying effect of the metallic salts in question, on the siccative oils used in printing inks. It appears that, owing to the fact that the ink and the salt are brought together on a fibrous substrate of very large micro-porous area, the oxidation reaction involved in the drying of the oil takes place more rapidly than it would if such a salt were mixed into the ink at a similar temperature prior to printing.

The latter effect is of great value in connection with newspaper printing where the presses operate at great speed, and the papers are sold very soon after printing. The quick drying achieved by the application of the invention assists in preventing smudging of fresh print.

The invention thus consists in a method of printing which includes the steps of selecting a paper coated on its surface with a thin continuous layer of one or more than one metallic salt of one or more than one longchain carboxylic acid having a chain-length of at least eleven carbon atoms in the molecule, the metal having a valency of at least two, and of transferring to the surface of said paper a printing ink which includes in its composition a. solvent for said metallic salt or salts.

Moreover, the invention comprises any article of printed matter printed by the method so defined.

The application of a suitable surface layer of metallic salt to paper may be carried out in a number of ways, for instance by the method described in my co-pending application Serial No. 583,479, filed May 8, 1956, now US. Patent No. 2,982,675, or in my further co-pending application Serial No. 649,381, filed March 29, 1957. The present invention is, however, not concerned with a particular method of application, and suitable methods will therefore not be described except to state that it may be carried out, for example by the use of an appropriate solvent which is afterwards evaporated or by a double-step reaction used for forming metallic soaps. It is however, not suflicient to incorporate such metallic salt in the paper pulp, but it must exist as a layer on the surface of the paper.

In the following, a number of examples are given for the purpose of illustrating the invention, and not with a view to limiting the ambit of the invention to these particular examples.

Example 1 A. surface coat of zinc stearate was applied to white lithe-paper having a weight of 136 gins/m the weight of the coat being of the order of 0.3% calculated on the paper weight. The paper so coated was printed with printing ink of normal composition, i.e. containing about 70% of carbon black and about 30% of rosin oil with a trace of cobalt acetate, to which 5% of linseed oil was added, all percentages being by Weight, the linseed oil in particular acting as a solvent for zine stearate and thereby assisting in reducing the drying time.

It was observed that the saving of ink achieved when printing on paper so coated was 25% as compared with printing on uncoated paper of the same specification with the same ink, but was about 27% if ink of normal composition was used. It was further observed that the drying time was reduced to 8 hours with the ink containing linseed oil and to 9 /2 hours with the ink of normal composition as against the required drying time of 12 hours for the uncoated paper. The print itself was more sharp and the color of the print brighter with each type of ink if coated paper was used.

Example 2 A surface coat of zinc stearate was applied to white litho-paper having a weight of 136 gms./rn. the weight of the coat being of the order of 0.8% calculated on the paper weight. The paper so coated was printed with printing ink of the normal composition (see Example 1) to which 5% by weight of linseed oil was added.

It was observed that the saving of ink achieved when printing on the paper so coated was 30% as compared with printing on uncoated paper of the same specification with the ink containing the linseed oil, but was 32% if ink of normal composition was used. The drying time was reduced to 6 hours as against 8 hours for the uncoated paper and ink diluted with linseed oil, but was reduced to 7 hours only when ink of normal composition was used. The print itself was more sharp and the color of the print brighter with each type of ink if coated paper was used.

Example 3 Like Example 2 except for the fact that 20% by weight of linseed oil was added to the normal printing ink. In this case the saving of ink amounted to 35% as compared with printing on uncoated paper of the same specification with the same ink. The drying time was found to be 4 /2 hours as against 12 hours in the case of the uncoated paper, and the print proved to be very sharp and bright.

' Example 4 A superficial coat of cobalt resinate which is substantially a cobalt salt of abietic acid, was applied to the surface of so-called system board having a weight of 150 grns./m. the weight of the coat being 0.05% calculated on the paper weight. The paper so coated was printed in multi-color by a wet process with blue and yellow printing inks each containing about 70% by weight of pigment (Prussian blue and chrome yellow, respectively) and about 30% of rosin oil with a trace of cobalt acetate, with 5% by weight of kerosene added to each of these inks, the kerosene acting as a solvent for the cobalt resinate and thereby promoting the drying of the ink.

The saving of blue ink amounted to 20% and that of yellow ink to 35% as compared with printing with the same inks on uncoated paper of the same quality. The drying time was hours as compared with 24 hours in the case of uncoated paper. The print proved to be clearer than on uncoated paper, and the mixing of colors easier to effect.

Example 5 Like Example 4, except that the cobalt resinate coat was considerably thicker, its weight being 2% calculated on the paper weight.

The saving of blue ink amounted to 50%, and that of yellow ink to 35%, as compared with printing with the same inks on uncoated paper of the same quality. The drying time however was very considerably reduced to 2 hours as against 24 hours in the case of the uncoated paper. The print proved to be sufficiently clear and the different colors could be applied to the paper in immediate succession, without aftecting the quality of the print.

A comparison of Example 4 with Example 5 shows that with increasing thickness of the cobalt resinate coat, the drying time could be reduced very considerably. In the actual practice of printing however, such heavy coats would not be used for reasons of economy. Besides this, the application of a thick coat tends to reduce the number of pores in the paper and consequently affects the penetration of the ink into the latter. As a result a more satisfactory quality of the print is achieved with a comparatively thinner coat of cobalt resinate.

Example 6 The same as in Example 5, with the exception of the printing ink which contained 5% by weight of paraffin oil and 5% by weight of kerosene. The saving of ink and the reduction in drying time were the same as those observed in Example 5.

Example 7 A coat of manganese salt of oleic acid was applied to the surface of white lithe-paper having a weight of 150 gms/mfl, the weight of the coat being 2.5% calculated on the paper weight. This paper was printed with black printing ink of normal composition diluted with 40% by weight of boiled linseed oil, the latter acting as a solvent for the manganese salt.

The saving of ink obtained when printing on the coated paper was about 30% as compared with printing on incoated paper of the same quality with the same ink. The drying time was reduced to 6 hours, from 18 hours required for the untreated paper.

Example 8 A surface coat of equal parts of copper salts of stearic and oleic acids was applied to white litho-paper having a Weight of 136 gms./m. the weight of the coat being 2.8% calculated on the paper weight. This paper was printed with black ink of normal composition containing additionally 10% by weight of soya bean oil. The saving of ink achieved by printing on the coated paper as compared with printing with the same ink on uncoated paper of the same quality was about 50%. The drying time was reduced from 20 hours in the case of the uncoated paper, to 8 hours in the case of the coated paper. The print was very sharp and clear, even though the printing block showed considerable wear.

Moreover it was observed that the printing speed could be increased by 25% without any ill effect on the quality of the print, presumably due to the reduced adhesion of the paper to the block during the printing process.

Example 9 A surface coat of aluminium stearate was applied to white litho-paper weighing 136 gms./m. the weight of the coat being 0.5% calculated on the paper weight. The coated paper was printed with normal black printing ink containing additionally 10% by weight of kerosene which acts as a solvent and therefore as an activator for the aluminium stearate.

The saving of ink obtained when printing on paper so coated was 39%, compared with printing on uncoated paper of the same specification with the same ink. The necessary drying time was reduced to 3 hours from 9 hours required for the untreated paper. In this case also, the print proved to be more distinct and sharp, and of deeper blackness than in the case of the untreated paper.

Example 10 Like Example 9, except that the weight of the coat of aluminium stearate was 3% of that or the paper.

The saving of ink observed in this case was 40% compared with printing on uncoated paper of the same specification with the same ink, whereas the drying time was reduced from 9 hours to 4 hours only. The quality of the print was substantially the same as that achieved in Example 9.

By comparing the results of Examples 9 and 10 it will be seen that the use of a thicker coat is hardly warranted. The gain, if any, in the saving of printing ink is negligible, whereas the reduction in drying time is less.

Example 11 The same type of paper as in Example 9 had applied to its surface a coat of aluminium stearate, the weight of the coat being 3% of that of the paper itself. The coated paper was printed with normal black printing ink containing additionally 5% by weight of boiled linseed oil and 30% by weight of kerosene. The saving of ink by printing on the coated paper, as compared with printing on the uncoated paper, was about 50%, and the drying time was reduced to 3 hours from 10 hours. Here again the print proved to be more distinct, sharp, and of deeper blackness than in the case of the untreated paper.

When comparing the results obtained with Example 10 it will be seen that the increased quantity of solvent and activator for the aluminium stearate caused'a comparative reduction in the drying time.

Example 12 To standard newsprint a coat or layer of aluminium stearate was applied, the coat increasing the paper weight by 0.9%. The paper was printed on a standard rotary the same working conditions. immediately after leaving the press, smudging being altogether eliminated. The print proved to be very sharp and of a deep black color.

Example 13 Like Example 12, except that the coat of aluminium stearate increased the paper weight by 1.6%. The saving of ink was thereby increased to about 53% under the same working conditions. it would appear that the increased saving of ink does not justify the use of a thicker coat on either economical or any other grounds.

Example 14 A coat of nickel resinate, being substantially a salt of abietic acid, was applied to the surface of white lithopaper having a weight of about 136 gms./m. the weight of the coat being 0.05% calculated on the paper weight. The coated paper was printed with normal printing inks of difierent colors each with an addition of 20% by weight of boiled linseed oil which acts as a solvent and activator for the nickel resinate.

The saving of printing ink on the coated paper was 15 to 20%, as compared with printing on uncoated paper of the same quality with the same ink. The drying time was reduced to 6 hours from 12 hours for the untreated paper. All colors showed increased brightness when compared with printing on the untreated paper.

The examples described above illustrate that in printing on a porous paper surface coated with a continuous layer of one or more than one Water-insoluble higher fatty acid salt of a metal having a valency of at least two, great advantages of an unexpected nature are achieved which include a considerable saving of printing ink and a notable reduction of the drying time as compared with printing on paper devoid of such coat. A further important advantage lies in the fact that due to the saving of printing ink and the considerable reduction of lateral flow of ink across the paper fibres, the clarity of the print is greatly enhanced. These advantages can be achieved with printing inks of normal composition Which always contain rosin oil or some other oil and/or hydrocarbons as oleaginous vehicle for the pigment or pigments, said oleaginous matter acting as a solvent for said metallic salt and thereby causing the salt to act as an effective drier for the ink, in addition to such drier or driers as are usually contained in printing inks in small quantities.

For carrying out the method according to the invention any water-insoluble salt of a metal having a valency of at least two with a long-chain carboxylic acid having a chain-length from 11 to 20 carbon atoms can be used, in theory. Many such salts, however, will be excluded in practice, either for reasons of economy or because of the toxicity of such salts. Others, such as iron and magnesium salts, will not normally be used in practice as these salts are not considered effective driers unless subjected to additional treatment. Copper salts if used in the process usually give to the paper a bluish tinge. Therefore they may be used with advantage on off-white paper for the purpose of reducing its yellowish tint. As a rule, however, they will not be used on paper of sufiicient whiteness.

Amongst the long-chain carboxylic acids, those of natural origin having a chain-length from 12 to 20 are preferred, mainly because they are comparatively inexpensive, but synthetic long-chain carboxylic acids having chain-lengths of 11, 13, 15 or 17 carbon atoms are also usable for the purpose.

The thickness of the coat on the paper may vary within wide limits. It is preferably determined by comparing the weight of the uncoated paper with that of the coated paper. If the coat contains salts which are highly effective as driers. such as cobalt resinates or nickel resinates, it may then be very thin, for instance so thin that the The print dried almost weight of commercial types of paper is increased by about 0.02 to 0.1% only. If other salts such as zinc stearate or aluminium stearate are used, the required increase of the paper weight may be between 0.2% and 1.6%, depending on the extent of saving in ink and/or of the reduction in the drying time aimed at. In general, very satisfactory results are achieved with coats of zinc stearate or aluminium stearate which increase the paper weight by between 0.5 to 1%.

The coat or layer of water-insoluble salt will adhere to the paper surface more or less permanently, depending on the method used for the application or precipitation of the salt on the paper surface. It is desirable, however, to assure permanency of the coat by embedding same in a suitable fixative. One method of so embedding the salt or salts is described for instance in my copending patent application Serial No. 649,381 of March 29, 1957, entitled Paper, Particularly Printing Paper, and Method of Making Same.

As pointed out above, the advantages of the invention are attained with practically any type of printing ink containing rosin oil or some other oil and/or hydrocarbon as oleaginous vehicle. The percentages in printing ink of pigment or pigments and vehicle substance vary Widely, depending on the particular nature of the pigment or pigments. The percentages stated above in Examples 1 and 4 must not therefore be taken as limiting the scope of invention to any particular type of printing ink, but as representing only those types of inks which were available to the applicant for his experiments.

Quantities of linseed oil, kerosene and/or other oils and hydrocarbons varying between about 2% and 30 to 40% of the undiluted ink will in most cases be added only if it desired to obtain a considerable reduction of the drying time.

What I claim is:

1. Method of printing on paper, paper-board and the like with printing ink containing at least a pigment and an oleaginous vehicle, which comprises applying sad printing ink to a paper, paper-board and the like provided on the surface to be printed with a thin and continuous coat consisting essentially of a water-insoluble higher fatty acid salt of a metal having a valency of at. least two, said continuous coat being present upon said paper prior to the application of said printing ink thereto and said coat and said printing ink being difierent from each other and wholly independent of each other prior to said application, and said oleaginous vehicle having a solvent action upon said salt in said coat and said salt in said coat having a drying action upon said ink, whereby mutual interaction between said coat and said ink occurs.

2. The method as claimed in claim 1, wherein said water-insoluble salt is a salt of a long-chain carboxylic acid having a chain-length from 11 to 20 carbon atoms.

3. The method as claimed in claim 2, wherein the printing ink is diluted by the addition thereto of one member of the group consisting of linseed oil, boiled linseed oil, kerosene, paraffin oil and soya bean oil.

4. The method as claimed in claim 3, wherein the quantity of the diluent added to the printing ink is between 2% and 40% by weight.

5. The method as claimed in claim 4, wherein the quantity of the diluent added to the printing inkis between 5% and 10% by weight.

6. The method as claimed in claim 1, wherein said coat includes at least one member of the group consisting of zinc stearate, aluminium stearate, copper stearate and copper oleate.

7. The method as claimed in claim 6, wherein the increase of the paper weight by the application of said coat is from about 0.2% to about 1.6%.

8. The method as claimed in claim 6, wherein the increase of the paper weight by the application of said coat is from about 0.5% to about 1%.

9. The method as claimed in claim 6, wherein the 7 printing ink is diluted by the addition thereto of at least one member of the group consisting of linseed oil, boiled linseed oil, kerosene, paraffin oil and soya bean oil.

10. The method as claimed in claim 1, wherein said coat includes at least one member of the group consisting of cobalt resinate and nickel resinate.

11. The method as claimed in claim 10, wherein the increase of the paperweight by the application of said coat is from about 0.02% to about 0.1%.

12. The method as claimed in claim 10, wherein the printing ink is diluted by the addition thereto of at least one member of the group consisting of linseed oil, boiled linseed oil, kerosene, paraffin oil and soya bean oil.

13. The method as claimed in claim 1, wherein the printing ink is diluted by the addition thereto of a solvent for the water-insoluble higher fatty acid salt of a metal having a valency of at least two.

14. The method as claimed in claim 1, wherein the printing ink is diluted by the addition thereto of one member of the group consisting of linseed oil, boiled linseed oil, kerosene, paraffin oil and soya bean oil.

15. The method as claimed in claim 13, wherein quantity of the diluent added to the printing ink is tween 2% and 40% by weight.

16. The method as claimed in claim 14, wherein quantity of the diluent added to the printing ink is tween 2% and 40% by weight.

17. The method as claimed in claim 15, wherein quantity of the diluent added to the printing ink is tween 5% and by weight.

18. The method as claimed in claim 16, wherein quantity of the diluent added to the printing ink is tween 5% and 10% by weight.

19. A web of paper, paperboard and the like having on at least one face thereof a thin and continuous coat consisting essentially of a water-insoluble higher fatty acid salt of a metal having a valency of at least two and the residue of a printing ink overlying and combined with at least a portion of said coat, said ink including a pigment and an oleaginous vehicle, said oleaginous vehicle having a solvent action upon said sailt in said coat, and said salt in said coat having a drying action upon said ink, whereby said residue comprises the products of interaction between said ink and said coat.

20. A web as defined in claim 19, wherein said coat includes at least one member of the group consisting of zinc stearate, aluminium stearate, copper stearate and copper oleate.

21. A web as defined in claim 19, wherein said coat increases the weight of said web by 0.5 to 1%.

22. A -web as defined in claim 19, wherein said coat the bethe bethe bethe beincludes at least one member of the group consisting of cobalt resinate and nickel resinate.

23. A web as defined in claim 22, wherein said coat increases the weight of said web by 0.5 to 1%.

24. A web as defined in claim 22, wherein said ink includes a further solvent for said salt.

25. A web as defined in claim 24, wherein the quantity of said solvent is between 2% and 40% by weight of said ink.

26. A web as defined in claim 19, wherein the printing ink is diluted by the addition thereto of one member of the group consisting of linseed oil, boiled linseed oil, kerosene, paraffin oil and soya bean oil.

27. A web as defined in claim 26, wherein the quantity of said diluent is between 2% and 10% by weight of said ink.

28. A web as defined in claim 26, wherein the quantity of said diluent is between 5% and 10% by weight of said ink.

29. A web as defined in claim 19, wherein said coat includes at least one member of the group consisting of zinc stearate, aluminium stearate, copper stearate and copper oleate and wherein the printing ink is diluted by the addition thereto of at least one member of the group consisting of linseed oil, boiled linseed oil, kerosene, paraffin oil and soya bean oil.

30. A web as defined in claim 19, wherein the quantity of the diluent added to the printing ink is between 5% and 10% by weight and wherein the printing ink is diluted by the addition thereto of at least one member of the group consisting of linseed oil, boiled linseed oil, kerosene, paraffin oil and soya bean oil.

References Cited in the file of this patent UNITED STATE S PATENTS 1,430,998 Hoskins Oct. 3, 1922 1,811,804 Poschel June 23, 1931 1,829,877 Schroeder Nov. 3, 1931 2,204,550 Murray June 18, 1940 2,345,142 Muller May 11, 1943 2,635,055 Figdor Apr. 14, 1953 2,637,665 Dodge May 5, 1953 OTHER REFERENCES Printing Inks, Carleton Ellis, Reinhold Publishing Corp. (1940),pp. 100, 101, 205, 206.

Healey: Paint Manufacture, March 1943, XIII, pp.

Rudd: I. Oil Color Chem. Assoc., v. 21 (1944), pp.

Claims (1)

1. METHOD OF PRINTING IN PAPER, PAPER-BOARD AND THE LIKE WITH PRINTING INK CONTAINING AT LEAST A PIGMENT AND AN OLEAGINOUS VEHICLE, WHICH COMPRISES APPLYING SAD PRINTING INK TO A PAPER, PAPER-BOARD AND THE LIKE PROVIDED ON THE SURFACE TO BE PRINTED WITH A THIN AND CONTINUOUS COAT CONSISTING ESSENTIALLY OF A WATER-INSOLUBLE HIGHER FATTY ACID SALT OF A METAL HAVING A VALENCY OF AT LEAST TWO, SAID CONTINUOUS COAT BEING PRESENT UPON SAID PAPER PRIOR TO THE APPLICATION OF SAID PRINTING INK THERETO AND SAID COAT AND SAID PRINTING INK BEING DIFFERENT FROM EACH OTHER SAID WHOLLY INDEPENDANT OF EACH OTHER PRIOR TO SAID APPLICATION, AND SAID OLEAGINOUS VECHICLE HAVIN A SOLVENT ACTION UPON SAID SALT IN SAID COAT AND SAID SALT IN SAID CAOT HAVING A DRYING ACTION UPON SAID INK, WHEREBY MUTUAL INTERACTION BETWEEN SAID COAT AND SAID INK OCCURS.