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Publication numberUS2447379 A
Publication typeGrant
Publication dateAug 17, 1948
Filing dateApr 21, 1943
Priority dateApr 21, 1943
Publication numberUS 2447379 A, US 2447379A, US-A-2447379, US2447379 A, US2447379A
InventorsRoss Wenger Frederick
Original AssigneeFocal Company
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Process for metalizing nonmetallic articles
US 2447379 A
Abstract  available in
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Claims  available in
Description  (OCR text may contain errors)

Patented Aug. 17 1943 FROCESS FOR METALIZING NONMETALLIC ARTICLES Frederick Ross Wenger, Los Angeles, Calif., as- Signor to Focal Company, Downey, Califl, a corporation of California I No Drawing. Application'April 21, 1943, Serial No. 483,948

- 1 Claims. (Cl. inc-47) This invention relates to a process for the metalizationof plastics and other non-metallic substances, such as paper, Celluloid, sheet cork,

fivory, bone, hard rubber, wood, leather, cloth,

horn, pressed Woods, imitation leather, glass,

porcelain products and plastic materials which are not reactive to alcohols, ketones and esters,

and the products resulting therefrom,

It has heretofore been proposed to coat nonmetallic substances with metal, such as silver or copper, but these processes have not been entirely satisfactory due to cost, time consumed in treating the substance to be metalized, and lack ing the non-metallic substance, or article to be metalized, to three baths to be specified hereinafter, and then a platin operation of any Wellknown type now'in use. As one example of cardipped in the following. solution to oxidize the silver deposited on the sheet'i'n the firstdip:

To equal parts of water and denatured ethyl alcohol byv volume add 5 or 10% of alight metal hydroxide, such as sodium hydroxide or potassium hydroxide. The denatured alcohol content of this solution .should. not drop below 50%. When the hydroxide is added, the solution will turn an amber color. The solution should be allowed to age for at least 24h0urs before using. The treated sheet of plastic is now given a thirty second dip in this oxidizing solution at room temperature whereupon the solution oxidizes the silver on the sheet converting it. toeither silver hydroxide or silver oxide. If a. heavier coating is desired thesheet may beleft in thesolution for or 50 seconds. Itis then dried and'is readyfor a reducing bath.

In order to prepare the reducing bath a select- .ed quantity of water is saturated with sulfurdioxide gas to, obtain sulphurous acid,

rying out the novel process, the same will be j' described, merely for the purpose of illustration, .in' connection'with the metalization of plastics cellulose'nitrates, and cellulose acetates and plastics which do not react to alcohols, ketones and;

esters.

A plain, clean sheet of cellulose nitrate plastic is first subjected to abath of acetone, denatured alcohol and silver nitrate. This bath or solution is formed by dissolving silver nitrate crystals in, 1 denatured alcohol at a temperature of approximately 15 C'.,'or"slig'h't1y higher, and this mixture is added to acetone. Preferably the bath comprises 50 parts by volume of denatured ethyl alcohol, 50 parts by volume of acetone and silver nitrate crystals of from 5 to 10 parts of the mixture of acetone and alcohol. Nothing is gained by adding more than 10 parts by volume of silver nitrate although if an alcohol of a higher specific gravity is used a greater amount of silver nitrate crystals will be dissolved. The best results have been obtained by using ethyl alcohol in the bath where methyl alcohol or acetone is used as the denaturant. The plastic sheet is dipped into the bath at room temperature, 1. e., approximately 65 F., for thirty seconds and after this dip the article is dried, preferably in a stream of warm air.

After the initial silver dip, the plastic sheet is Sodium sulphite is now added to the sulphurous acid until the reaction of the acid ceases.

.There isthus obtained a saturate solution of so- 1 to c. c. of the stock solutionof sodium bisulphite is added 500 c. c. of water and into this is poured powdered zinc to obtain the following reaction:

This mixture is kept cool as by means of ice or cold water until the reaction between the zinc and the acid of the bisulphite has been completed. A portion of the zinc sulphite is converted into a basic salt and S02, thus set free, is then reduced in turn by the excessive zinc present. A reducing bath thus formed gives fair results if used within a few hours after it is first made but better results silver finish. The strip can then be plated with any suitable material, such as copper, where the required temperature of the plating bath is below the danger point of deterioration of the plastic base.

The-reducing. bath slowly oxidizes and hence must be' kept in a closed container. It has been found that if a small amount of sugar, honey, or glycerine is added, the oxidation will be slowed and the keeping properties improved. It is noted that meta bisulphite should not be used in making the reducing bath because if used sulphides will be formed and the results" willbe unsatisfactory.

When metalizing the other non-metallic substances referred to above, such as rubber, for 'example, it is preferred to make a solution of a cellulose nitrate plastic and acetone to the consistency of light cream. The rubber, Or other article, is dipped into this cream, then dried and processedin accordance with the procedure outlined v above for the cellulose nitrates strip.

'Therejis "thus" provided a novel and simple "niethod for metalizing non-metallic substances *and'one Whichcan be quickly and inexpensively "carried out. and has awi'de variety of uses as will be apparent to those skilled in the art.

Theproduct obtained is durable fWl'iat is claimed is: "1. A process for metalizing non-metallic arti- "cles ofthe class described-which includes the steps" of "subjecting the article to a bath of de- "'n'atured alcohol; acetone and silver nitrate, dry- "ingiand subjecting the article to a bath of'water, denatured alcohol andan alkali metalihydroxide,

' and'd'rylngand subjectingthe article to a reducingbeithof sodium bisulphite andzinc.

2. A process for metalizing non metallic articlesof the class described which includes the steps of treating the article with r a silver nitrate solution, subjecting the treated article to alcohol, metal hydroxide oxidation of the silver deposited thereon -from= the first s01uti0n,-and subjecting to :convert the :oxidized silver to metallic silver.

A process for-metalizing non-"metallic articles of theclass -described which consists in sub- :je ctingethe article toa silver nitrate-denatured alcohol-and an alkali metalhydroxida. drying the article,.i dipping the dried article in abath of sodium bisulphite and. zinc, and r washinguand drying the article.

4. A process for metalizing non-metallic arti cles..of :the class described which includesthe the article toa solution containing zinc sulphite steps of subjecting the article to a silver nitrate denatured alcohol-acetone bath, drying the article and subjecting it to an oxidizing bath of denatured alcohol, water and sodium hydroxide, drying the article and subjecting it to a bath formed by introducing powdered zinc into sodium bisulphite.

5. A process for metalizing a plastic article which consists in dipping the plastic article in a silver nitrate-denatured ethyl alcohol-acetone bath, drying the article, subjecting the dried article to a bath of water, denatured ethyl alcohol and sodium hydroxide, drying the article, dipping the driedarticle in a bath of sodium bisulphite and zinc, and washing and drying the article.

6; Aproc'ess for metalizing a non-metallic arti-.

cle of the class described which includes the steps of subjecting the article to a silver nitrate bath for approximately thirty seconds at room temperature, drying and subjecting thearticle to an oxidizing bath of water, denatured ethyl alcohol and sodium hydroxide at room"temperaturefor approximately thirty seconds, drying the-'article and subjectin the same to a bat-hcontainingzlnc 3 sulphite-for approximately'two minutes at" room temperature. r

7; A process for metalizing a nommetalllcarticle of the class described'whichincludesthe step of subjecting thearticle to a-solu'tion of cellulose nitrate and-acetone having abOnsis'tencyOI'light cream, drying the articlefsubje'ctingthearticle to a bath of denatured'alcoh'ol; ace'tone'and'silver nitrate, drying and "subjecting the "article "to an oxidizing bath of water, denatured alcohol and an alkali metal hydnoxide and drying-andsubjecting the'article to a reducing bath oil zinc and sodium-bisulphita H H V H FREDERICK" R O SS W'EN'GER.

REFERENCES- CITED FOREIGN PATENTS V Country, "Date" "GreatBritain 1915 anc Ju e; 1.9.2

Number Number

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US906229 *Jul 14, 1908Dec 8, 1908Heyden Chem FabProcess of mirroring glass or like surfaces.
US1452281 *Sep 10, 1921Apr 17, 1923Marino QuintinMetallizing articles
US1744281 *Nov 11, 1926Jan 21, 1930Radio Patents CorpMethod of applying a firmly-adhering metal coat to insulating plates, particularly for use in electric condensers
US1941438 *Mar 3, 1932Dec 26, 1933Karl KieferProcess for metallizing with reflecting highly polished surface celluloid in sheets and any other form by chemical means
US2351940 *Mar 13, 1940Jun 20, 1944Jules DupuisMethod of making plated articles
US2355933 *Apr 12, 1941Aug 15, 1944Cohan Epner Co IncProcess of metal plating
FR644429A * Title not available
GB191502698A * Title not available
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2689191 *Dec 10, 1948Sep 14, 1954Rca CorpFormation of reflecting coatings
US2996401 *Sep 30, 1955Aug 15, 1961Eitel Mccullough IncMethod of making ceramic structures for electron tubes
US4655811 *Dec 23, 1985Apr 7, 1987Donnelly CorporationCoating with indium-tin oxide, then carbonaceous material, then oxygen-free heating
Classifications
U.S. Classification427/343, 427/415, 205/167, 205/211, 205/220, 427/404
International ClassificationC23C18/44, C23C18/31
Cooperative ClassificationC23C18/44
European ClassificationC23C18/44