Patented Feb. 5, 1935 1989,764 UNITED STATES PATENT office 1989,764 PROCESS AND COMPOST ON FOR HE PRO. DUCTION OF REFLECTING SURFACES Max Meltsner, New York, N. Y. No Drawing. Application January 3, 1934, Serial No. 705,087 1. Claims, (C. 91-683) The invention relates to a method for the for upon which the reflecting. Surface is to be pro mation of a reflecting surface. More particu duced. The reaction may be brought about by ad larly, it pertains to a procedure for the prepara mixing a silver salt and an amino alcohol in re tion of a silvered reflecting surface and includes active proportions, placing the admixture thus 5 Correlated improvements and discoveries where formed upon the object to be silvered, and caus by the formation of such surfaces is enhanced. ing deposition of silver by increase in tempera The production of reflecting Surfaces, particu ture. The silver Salts which may be used are those larly silvering for mirrors, has previously been which are soluble to a fair degree in water or are effected by utilization of a composition contain So rendered when they are in a medium in the 10 ing a silver salt in conjunction with compounds presence of an amino alcohol. Various silver O capable of releasing the silver therefrom. The salts may be used, mention being made more spe compositions most frequently used consisted of cifically of the nitrate sulfate, acetate, chlorate, silver nitrate, a tartrate, ammonium hydroxide cyanide, fluoride and silver potassium cyanide. and/or potassium hydroxide. While under cer The amino alcohols employed are compounds s tain controlled conditions such compositions pro which are derivatives of ammonia in which one 5 duced a satisfactory reflecting surface, neverthe or more of the hydrogen atoms have been substi less failures were not infrequent and other disad tuted by an alcoholic radical, thus, for example, vantages attended. Thus potassium hydroxide, the beta-ethanolamines, as triethanolamine hav being of a highly caustic nature, was difficult not ing the probable formula only to store, but also to handle throughout the 20 preparation of the silvering composition and its ots CH2OH. subsequent use. N-CE. CHOH It is an object of the invention to provide a CE. COH method for the formation of reflecting surfaces In addition to triethanolamine other amino alco in accordance with which the disadvantages at hols may be employed as diethanolamine, mono 25 tending the procedures hitherto followed have in ethanolamine, and mixtures of the ethanolamines a large measure been obviated. in varying proportions. Other amino alcohols Another object of the invention is to provide that may be mentioned are the propanols and a method for the formation of a silvered reflect butanols. However, because of the availability 30 ing surface in which a silver salt is reacted with and low cost, it is preferred to use the ethanol 30 an amino alcohol. amines either perse or in suitable admixtures. A further object of the invention is to provide It will be realized that the reaction mixture a method for forming silvered reflecting surfaces may contain either a single Salt and a single which may be readily, efficiently and economical amino alcohol, or admixtures of silver Salts and ly carried out on a commercial scale. amino alcohols which are compatible. The re 35 An additional object of the invention is to pro flecting surfaces may be produced by means of vide a composition suitable for the formation of a number of procedures, and these will be illus silvered reflecting surfaces and containing a sil trated by means of the ethanolamines. Thus, ver salt and an amino alcohol, in reactive propor triethanolamine or diethanolamine, or mono 40 tions. ethanolamine may be added to a warm Solution 40 Other objects of the invention will in part be of silver nitrate, whereupon deposition of silver obvious and will in part appear hereinafter. is occasioned. Otherwise, the ethanolamine may . The invention accordingly comprises the sever be added to a solution of silver nitrate and the all steps and the relation of one or more of such mixture thus produced warmed with accompany 45 steps with respect to each of the others, and the ing deposition. 45 product possessing the features, properties, and Further, a solution of technical triethanolam the relation of constituents, which are exemplified ine, i. e., a mixture of the mono-, di- and tri in the following detailed disclosure, and the scope ethanolamines, may be added to a warm Solution of the invention will be indicated in the claims. of silver nitrate and heating continued, or a Solu In the practice of the invention the formation tion of triethanolamine may be added to a warm 50 of a reflecting surface, for example, a silvered solution of silver sulfate. mirror, may be effected by reacting a composi The foregoing procedures effect a satisfactory tion containing a silver salt and an amino alcohol deposition of silver upon the surface with which having the amino and hydroxyl groups joined to the solution, contacts with the formation of an different carbon atoms in contact with the object even and unpitted reflecting surface. 55 2 - 1,989,764 As illustrative embodiments of a manner in In the event that the mirror is produced on what which the invention is carried out in practice, the may be termed the reverse side of a plate glass, following examples are given: the finishing may be effected by applying any de Eacample I sired protective coating which may be a paint. s Since certain changes in carrying out the above 5 10 parts of silver nitrate solution having a Con process, and certain modifications in the Composi centration of about .1 normal is added to about tion which embody the invention may be made 20 parts of water. The solution thus obtained is without departing from its Scope, it is intended then heated in the neighborhood of 80-90, to that all matter contained in the above descrip 10 which there is added about 4 parts of technical tion shall be interpreted as illustrative and not in () triethanolamine in solution having a strength a limiting Sense. of about 3 molar. Heating of the composition It is also to be understood that the following thus obtained in contact with an object to be claims are intended to cover all of the generic and Coated results in the formation of a silvered mir specific features of the invention herein de - 5 ror Surface in about two minutes. scribed, and all statements of the scope of the in acample II vention which, as a matter of language, might be said to fall therebetween. A silver sulfate solution of a concentration Having described my invention, what I claim of about .02 molar and in a quantity of about 30 as new and desire to secure by Letters Patent is: 20 parts is heated to a temperature in the neighbor 1. A method for the formation of a silvered hood of 80° C. To the heated solution there is reflecting surface, which comprises reacting a added about 5 parts of triethanolamine, concen silver salt with a beta-ethanolamine. tration 3 molar, and heating continued in contact 2. A method for the formation of a silvered with the material to be silvered, with resulting reflecting surface, which comprises reacting a 25 formation of a mirror in a period of several silver salt with mixed beta-ethanolamines. minutes. 3. A method for the formation of a silvered Eacample III , reflecting surface, which compriseS reacting a silver salt with triethanolamine. To about 10 parts of a solution of silver nitrate 4. A method for the formation of a silvered 30 of a concentration about .1 normal, there is added reflecting surface, which comprises reacting about 2 to 4 parts of pure mono-ethanolamine. silver nitrate and a beta-ethanolamine in Solut The reaction mass so produced may then be tion. warmed to a temperature of about 80° C. in , 5. A method for the formation of a silvered contact with the object to be silvered, whereupon reflecting surface, which comprises reacting a mirror forms in a period of a few minutes. silver nitrate and triethanolamine in solution. In accordance with the method hereinbefore 6. A method for the formation of a silvered described, mirrors having a silvered surface may reflecting surface, which comprises reacting silver be produced readily and efficiently without the nitrate and triethanolamine in Solution at a tem necessary use of a highly caustic material, as parature in the neighborhood of 80 C. potassium hydroxide and a taitrate. Instead of 7. A silvering composition comprising a silver 40 utilization of a mixture of tartrate and caustic salt and a beta-ethanolamine. potash, there is employed a simple type of com 8. A silvering composition comprising silver pound, namely an amino-alcohol. It will be un nitrate and triethanolamine in reactive propor derstood that the invention is not limited to tions. 45 the specific materials and conditions of concen 9. A method for the formation of a reflecting tration and temperature set forth in the forego surface which comprises reacting a silver salt ing examples, but rather that there is encom with an amino alcohol of the group consisting of passed within its scope the utilization of various ethanol, propanol and butanol amines in which salts of silver and also various amino alcohols. the amino and hydroxyl groups are joined to 50 In view of the ready availability and low cost, it different carbon atoms. is preferred to form the silver surface by re 10. A method for the formation of a silvered action between silver nitrate and a beta reflecting surface which comprises reacting silver ethanolamine, specifically triethanolamine.