US2610128A - Silk-screen printing paste - Google Patents

Description

Patented Sept. 9, 1952 summing in =s1i1 -se1mnn PRINTING PASTE Frank Enoch Ker-ridge and Gyril Stanley' Gouper, London, Englaniassignors to Johnsonf Matthey & Company Limited,'Londom'xEngland, a

. Britishcompany N Drawing. Application July 18; 149,'Serial No.

.11oa44 4. In Great Britain July 27, 1948 earthenware. and. china and'iis more particularly concerned with the decorationofi suchi'bases with "a design or decoration irr platinum'iori having a platinumorsilver likeappearance.

. Platinum decorations. or decorations having a platinum or silver appearance have in eneral heretofore beenwproduced on glass, china or :ear'thenware .by fthe use. orone of" theifollowing j materialanam'ely: I ,1

(1 'Liquid platinum whichoonsi'sts essential- ,ly. of -..a.;.so1uti0n of..platinum sulphoresinate in suitable. solvents; M

'(2) Liquid white gold (popularly known as liquid silver) which consists essentially of a :mixture; in suitablesolvents, l )of platinum and :gold. sulphoresinates,.-a mixtureof. palladium and 1 gold .sulphoresinates, on :a mixture ofz platinum,

palladium, and-goldsulphoresinates;

(3) .Liquid bumish white-gold (sometimes known as liquid burnish-silver?)econsistingxof a suspension of gold or a gold compound in a solution of gold aridplatinum sulphoresinates, or of goldand palladium sulphoresinates: andfinfs'ome cases; including a mercury compound: I

' (4)Finelydivided (usuallyprecipitatedrplatinum powder, with or without a powdered mercury compound;

' (5) Einely'dividd platinum-or palladiumswith goldpowder, with or without--a 'powdered mercury compound.

All ottheabove materials contain an adhesion;

.ly l-rubber: stampnprintin'g or zengraved .aplate reprinting. l A w v 1 .l'llhenubber stamp m'ethodywhilstbeingwimpie =-':and' rapidin usty-results in J a 'idesign -whiclig is deckinginrihnss-and=sharpness ofbiitline no,

moreoven aoes not-enable ceramic colours to-be I aiLpriinted simultaneously in register with the platiinummrplatinum-like decoration.

' -With engraved-plate or copper-plate printing a transfer -is "prepared by engraving' or etchinga design on a copper "or glass plate; filling the inter- "stices or depressions so formed with-the printing paste, applying a sheet ofgummd tissuepaper,

'gummed' side downwards to the'coated'plate' and then removingthe paper, which-nowcarries the plied; whilstthe paste is: still moist or sticky with "the "design-carrying side downwards, to l the article. "The tissue paper is then soaked on and the-article fired. l i This'methodj'in the handset a 'sk'illed operator,

gives a' deooration of good q'ualityi but, as the design is applied to the 1 ware in the moist state; it cainnot *be used'for applying both-platinum, Ora platinum-like decoration and a ceramic ool'our simultaneously in register. Afurtherdisadvanea ceramic =colour transfer *by the silk screen printing method. 7 -Silk-scren printing; whether used ror decorating'an artiCle by direct application" or for the "preparation of transfers-"offers" advantages over i the othermethods'referred toin that theapparatuseemployed is inexpensive, a variety of decorative efiects are obtainable and -"print pfhigh dualityand 1 well-defined outlines can -be readily produced by relatively unskilled workers.

\ 'Pastes embodying 'the "above mentioned-'matepreparationbftransfers "rials as heretofore" constitutedior :usewith; the rubber stamp"orengraved plate printingmethods are quite" unsuited for use with the silk-screen printing method, particularly in the' easeofthe Itwi-lt =beappreciated from-a Y consideration of 1 the above that, itaplatinum paste or one-giving a :platinum or's'ilver-like appearance; :were providedg which could besatisfactorily applied by the "silk-screen printing me'thod, very considerable advantages would accrue both from the artistic and the commercial -aspects. In "the first'pla'ce.

it-would-be-possibleto decorate an article with a d sign in platinum, which would have amore {pleasing f-efiect thanfi those hitherto obtainable with the hitherto known methods, owing to"'the improveddfini'tion or the outlines and 'the'fact that it becomes possible to print a ceramic colour design in register with the platinum, and secondly, the process of decorating can be carried out relatively inexpensively.

Silk-screen printing, however, produces a. very thick deposit and whilst this is in many instances, particularly in the case of ceramic enamels, greatly to be desired, it may be that, in the case of a platinum decoration, the cost of the platinum may outweigh the advantages attainable by the use of his method. Attempts to produce a thinner deposit by employing a low platinum, or like.

precious metal, to medium ratio will result in unsat s ory P g owing to the low proportion of solid in the paste, and frequently in flowing of the prints and loss of sharpness of outline before drying.

An object of the invention is to overcome the I I above disadvantages and to provide an improved platinum paste suitable for direct application to an article to be decorated by the silk-screen printing method or for the preparation by the silk-screen printing method, of transfers intended for subsequent application to an article.

Another object is to enable a thin deposit of platinum to be applied to a heat resisting base by the silk-screen printing method.

, A further object is to enable the thickness of the platinum deposit to be readily controllable.

Another object is to provide a silk-screen printing paste including platinum powder and a volatilisable solid, which will volatilise without carbonising during the subsequent 'firingof a heat-resisting base decorated with the paste.-

- A still further object is to provide a silk-screen printing paste comprising platinum powder, a flux or adhesion promotingagent having a melting point not higher than 500 C., an organic silk-screen printing medium or vehicle, and a volatilisable solid.

By including a volatilisable solid in the paste, the amount of precious metal in the paste, and hence the thickness of the final precious metal film obtained after firing, may be varied as desired, sinceby suitably proportioning the amount of volatilisable solid included, the ratio of liquid to total solids in the paste may bemaintained in the correct proportion to give good printing qualities.

The volatilisable solid may consist of any solid which volatilises completely at a low temperature, but we have found that certain organic materials, such as oxanilide, aoetanilide or anthracene are more suitable than volatilisable inorganic materials, such as ammonium chloride. Of-the organic materials mentioned, we prefer to use anthracene.

- The proportion of medium to solid substances is preferably 1-4 parts of medium to 2 parts of solid, the exact proportions depending on the particle: size. of the solids and the viscosity of the medium.

The organic medium will comprise a -film- .forming ingredient dissolved in a solvent, for

example it may be a cellulose derivative or a natural or synthetic resin or resins or a'mixture thereof dissolved in-a solvent or solvent mixture having a rate of evaporation suitable for silkscreenprinting. For example, the medium may consist of nitrocellulose dissolved in amyl and/or ethyl lactate vor of colophony dissolved in pine Dill, v I I The flux may be alead borosilicate or a lead alkali borosilicate fiuxor .a bismuth compound, such asbismuth oxide or, oxychloride.

' Per cent by weight (1) Platinum powder 40 Mercurous chloride 10 Low fusing lead borosilicate flux 3.5 volatilisable solid (anthracene) 2.5 'Plasticised nitrocellulose medium 44 e the constituents beingground together toform a paste. v

i Per cent by weight (2) Platinum powder 40 Mercurous chloride 10 Low fusing lead borosilicate flux 3.5 volatilisable solid (anthracene) 2.5

Plasticised resinous medium "44 the constituents being ground together to form a paste.

In the case of the decoration of a pottery article, a lower percentage of flux may be used, since a higher firing temperature can be employed than with glass.

The preferred composition of the individual constituents of our improved paste is as follows:

Flux or adhesion promoting constituent Although many lead borosilicate or lead alkali borosilicate fluxes which melt at a temperature of 400-500 C., or a bismuth compound may be used, we have found that the most satisfactory results are obtained by using a flux having the following composition:

Lead monbnd'e (PbO) Y Boric oxide,(B: )a) 7.0

Silica (SiOz), v.5

Medium If a medium based on a cellulose derivative is employed, the following composition will be found suitable:

Per cent by weight Amyl lactate 56 Ethyl lactate 20 Nitrocelluloselmedium viscosity) 8 Methyl abietate '8 Castor oil '8 If a resinous medium is employed, the following composition will be found suitable::

. Per centby weight Pine oil '10 Colophony 20 Methyl abietate 5 Castor oil 5 In the use of our improved paste for the dewration, for example, of a substantially flat article of glassythe paste is applied to the article, so

astto form any desireddesign--thereon,.--by the silk-screen printing method, and allowed to'dry.

The coated articleis then fired at. a temperature Per cent by weight within the range of 500-4350 C. depending on the type of glass, to burn away the organic matter and cause the precious metal or metals to adhere firmly to the article.

If the base being decorated is of earthenware or china, the firing temperature is preferably between 650 and 800 C.

The decoration, after firing, will present a matt surface, and should be lightly scoured with sand or burnished with agate so as to produce a bright effect.

When the paste is to be used for preparing a transfer, the paste is applied, in any desired design, to a sheet of transfer paper by the silkscreen printing method and is again allowed to dry. To decorate an article, the transfer paper with the design thereon is applied to the article and the design transferred to the surface thereof by the well-known slide-off method. The article is then fired at a suitable temperature, i. e. within the range of 500-650 C. in the case of a glass article and 65-0-800 C. in the case of earthenware or china. The fired design may, in this case also, be lightly burnished. It is to be understood that the improved paste may be printed so as to register with a vitreous enamel or ceramic colour in a combined platinum or silver-like and enamel decoration.

As will be appreciated, our invention enables an article to be provided with a decoration having the appearance of silver, but which does not tarnish on exposure to air.

What we claim is:

1. A silk-screen printing paste for the preparation of a transfer or for direct application to a heat-resisting base, said paste comprising a mixture of platinum powder, anthracene, a ceramic flux and an organic vehicle consisting of 56% by weight of amyl lactate, 20% by weight of ethyl lactate, 8% by weight of nitrocellulose, 8% by weight of methyl abietate and 8% by weight of castor oil and the relative proportions of platinum powder, ceramic flux and anthracene to liquid vehicle being always substantially 2 parts of solids to 1-4 parts of vehicle.

2. A silk-screen printing paste for the preparation of a transfer or for direct application to a glass base, said paste comprising a mixture of the following constituents in the following proportions by weight, namely:

Per cent Platinum powder 40 Mercurous chloride 10 Lead borosilicate flux 3.5 Anthracene 2.5

Solution containing plasticized nitrocellulose 44 3. A silk-screen printing paste for the preparation of a transfer or for direct application to a heat-resisting base, said paste consisting essentially of a platinum powder-ceramic flux mixture and anthracene, said platinum powder-ceramic flux and anthracene constituting solid ingredients, and an organic screening vehicle comprising nitrocellulose dissolved in a solvent selected from the group consisting of amyl lactate, ethyl lactate and mixtures thereof, and the relative proportion of the combined amounts of platinum powder-ceramic flux mixture and anthracene to liquid vehicle being always substantially two parts of solids to 1-4 parts of vehicle. 7

4. A silk-screen printing paste for the preparation of a transfer or for direct application to a heat-resisting base, said paste consisting essentially of a platinum power-lead borosilicate flux mixture and anthracene, said platinum powderlead borosilicate flux and anthracene constituting solid ingredients, and an organic screening vehicle comprising nitrocellulose dissolved in a solvent selected from the group consisting of amyl lactate, ethyl lactate and mixtures thereof, and the relative proportion of the combined amounts of platinum powder-lead borosilicate flux mixture and anthracene to liquid vehicle being always substantially 2 parts of solids to 1-4 parts of vehicle.

5. A silk-screen printing paste for the preparation of a transfer or for direct application to a heat-resisting base, said paste consisting essentially of a platinum powder-ceramic flux mixture, said ceramic flux being selected from the group consisting of bismuth oxide and bismuth oxychloride, and anthracene, said platinum pow der-ceramic flux and anthracene constituting solid ingredients, and an organic screening vehicle comprising nitrocellulose dissolved in a solvent selected from the group consisting of amyl lactate, ethyl lactate and mixtures thereof, and the relative proportion of the combined amounts of platinum powder-ceramic flux mixture and anthracene to liquid vehicle being always substantially 2 parts of solids to 1-4 parts of vehicle.

FRANK ENOCH KERRIDGE. CYRIL STANLEY COUPER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 255,421 Dode Mar. 28, 1882 460,358 Buttler Sept. 29, 1891 1,752,462 Smith Apr. 1, 1930 2,113,449 Hoffman et a1 Apr. 5, 1938 2,190,210 Kaber Feb. 1.3, 1940 2,287,053 Murphy June 23, 1942 2,294,760 Morris Sept. 1, 1942 2,318,803 Schneider et al. May 11, 1943 2,452,805 Sussenbach Nov. 2, 1948 FOREIGN PATENTS Number Country Date 7. 688 Great Britain 1892 9,261 Great Britain 1894 428,743 Great Britain May 17, 1935 526,853 Great Britain Sept. 26, 1940 566,718 Great Britain June 10, 1945

Claims (1)

1. 3. A SILK-SCREEN PRINTING PASTE FOR THE PREPARATION OF A TRANSFER OR FOR DIRECT APPLICATION TO A HEAT-RESISTING BASE, SAID PASTE CONSISTING ESSENTIALLY OF A PLATINUM POWDER-CERAMIC FLUX MIXTURE AND ANTHRACENE, SAID PLATINUM POWDER-CERAMIC FLUX AND ANTHRACENE CONSTITUTING SOLID INGREDIENTS, AND AN ORGANIC SCREENING VEHICLE COMPRISING NITROCELLULOSE DISSOLVED IN A SOLVENT SELECTED FROM THE GROUP CONSISTING OF AMYL LACTATE, ETHYL LACTATE AND MIXTURES THEREOF, AND THE RELATIVE PROPORTION OF THE COMBINED AMOUNTS OF PLATINUM POWDER-CERAMIC FLUX MIXTURE AND ANTHRACENE TO LIQUID VEHICLE BEING ALWAYS SUBSTANTIALLY TWO PARTS OF SOLIDS TO 1-4 PARTS OF VEHICLE.