Patented Feb. 20, 1951 2,542,070

UNITED STATES PATENT of FICE 2,542,070 SOLUTIONS OF POLYMERIC CHLORO TRFLUOROETHYLENE Murray M. Sprung and Frederick O. Guenther, Schenectady, N. Y., assignors to General Elec tric Company, a corporation of New York No Drawing. Application November 25, 1949, Serial No. 129,533 10 Claims. (C. 260-33.6) 2 This invention is concerned with Solutions of taining at least 10 per cent, by weight, solids of polymeric chlorotrifluoroethylene. More partic the polymeric chlorotrifluoroethylene, whereas ularly, the invention relates to a solution corn formerly the solubility of the polymer in other prising (1) polymeric chlorotrifluoroethylene dis Solvents was negligible. solved in (2) an aromatic Selected In addition to the advantages described above from the class consisting of pseudocumene, for our invention, we have also found that such , tertiary-butylbenzene, p-tertiary Solutions are accompanied by still further advan butyltoluene, beta - methylnaphthalene, alpha, tages. Among these are the ability to deposit beta-dimethylnaphthalene, amylbiphenyl, alpha more uniform and more homogeneous coatings methyl, para-methylstyrene, para-cymene, di O on such materials as electrical conductors, par (styrene dimer), diamylbiphenyl, para ticularly magnet wire. In addition, these hot ditertiary butylbenzene, mixtures of alkylated Solutions have a definite advantage over the use obtained in the distillation of of Some suspensions of polymeric chlorotrifluoro fractions and in the cracking or hydroforming of since, by means of application of a poly select petroleum fractions, as well as mixtures of 5 ner from hot solutions, the deposited film is con the foregoing solvents. tinuous and requires no fusion at elevated tem Polymeric chlorotrifluoroethylene has been peratures to cause coalescence of the individual found to have good heat resistance and chemi particles in the coating. When employing sus cal resistance and because of this is eminently pensions or dispersions, high temperatures are suitably for many applications where such prop- : necessary to cause fusion of the individual par erties are desired. Electrical conductors insu ticles which, although closely packed together, lated with polymeric chlorotrifluoroethylene are are nevertheless not continuous. Also, when ap capable of withstanding temperatures of the plying coatings on magnet wire by means of the order of from about 150° to 200° C. for long pe above-described solutions, conventional magnet riods of time with little change in the physical 25 wire dies can be used, permitting a more uniform characteristics or the insulating properties of the build-up of film thickness. Finally, because of polymeric insulation. Such polymeric material the lower temperatures at which coating of var is also highly desired for many applications where ious materials can be effected, thermal effects on its high Softening point is an advantage. Thus, the polymer are minimized. it is possible to mold various objects from the 30 In accordance with our invention, we prepare polymeric chlorotrifluoroethylene, either with or a mixture of finely divided polymeric chloro without fillers, to give useful articles which are trifluoroethylene and the aromatic hydrocarbon dimensionally stable over a wide temperature and heat the mixture at a temperature Sufficiently range. high to cause the polymer to dissolve in the sol Because of its extreme chemical resistance, 35 vent. Generally, we have found that solution in high flow point, and substantial insolubility in the particular class of solvents employed herein many of the common organic Solvents, great dif takes place at temperatures of the order of from ficulty has been experienced in obtaining the about 135 to 300° C. By maintaining these solu polymeric chlorotrifluoroethylene in usable form tions at the temperatures at which solution of whereby it can be employed for coating or im d) the polymer has taken place, we are able to em pregnating applications. Many attempts have ploy the Solutions in the same manner as solu been made to form solutions of the polymeric tions of other better known polymers. If the chlorotrifluoroethylene, but these have generally temperature is allowed to drop much below the been unsuccessful because the limit of solubility Solution temperature, small amounts of the poly of the polymeric chlorotrifluoroethylene in the ner will begin to settle out while larger amounts solvent has been so Small as to render it imprac will begin to precipitate as the temperature of tical. the Solution drops still further. Despite this, We have now discovered that we are able to however, this is believed to be the first time that make Solutions of polymeric chlorotrifluoro it has been possible to obtain solutions of such ethylene (any solid polymer thereof) whereby it 5) relatively high concentrations of the high poly is possible to obtain concentrations of the latter neric chlorotrifluoroethylene even at elevated polymer in the solution in sufficiently large temperatures. amounts as to make them useful in many coating Among the aromatic kydrocarbons which we and impregnating applications. By means of our have found to be suitable in the practice of our invention, it is possible to obtain solutions con- 5s invention are pseudocumene (1,2,4-trimethylben 9,549,070 3 4. zene), mesitylene (1,3,5-trimethyl ), pe using the various solvents recited previously. In tertiary - butyltoluene, tertiary butylbenzene, each case, 10 per cent, by weight, polymer and 90 alpha-methylstyrene, para-cymene, methylnaph per cent, by weight, solvent were employed so that thalene, dimethylnaphthalene, amylbiphenyl, di there was obtained a ten per cent solution of the amylbiphenyl, para-ditertiary-butylbenzene, sty polymer in the particular solvent. After mixing rene, dinner, etc. the polymeric chlorotrifluoroethylene (no Among the mixtures of liquid, Organic alkylated strength temperature 245° C.) with the particular aromatic which we may use are Solvent involved, the mixture was heated until those obtained, for instance, (1) by the cracking Solution thereof took place. The temperatures and distillation of the volatile portions of coal O at which Solution took place are noted in the tar and (2) mixtures of alkylated aromatic hy table below. drocarbons obtained by the cracking and hydro forming and Subsequent distillation of light pe Table it troleum oils, etc. An example of a mixture of alkylated aromatic hydrocarbons obtained from s For 10% coal tar comprises materials called "Hi-Flash' Conilpound Solution, Solution naphtha (also called "High Flash' naphtha) Temp., C. whose boiling range may be from 135° C. to 195° C. or Somewhat higher depending upon the cut l, 2,4-trimethylbenzene ------170 1,3,5-trimethylbenzene. 136-40 taken during distillation. Thus, one Such frac 20 beta-mothylnaphthalene. 240 tion may have a boiling range of 140° C. to 180° C., dimethylnaphthalene.--- 250-260 isoamylnaphthalene ------280 while another fraction may boil from about alpha-methyl, para-methylstyrene- 177 150° C. to 175° C. A typical analysis of Hi-Flash 0a2-cyltile------176 naphtha, comprises the following ingredients in tertiary-butylbenzene.-- 67 distyrene (cincr)------. 265-275 stipulated per cents, by weight: 25 para-tertiary-butyltoluene.---- 168 para-di-tertiary butylbenzene.------212 Per cent amylbiphenyl.------260-280 , , Cunene, propylbenzene, dianylbiphenyl------300 H:flash naphtha (boiling point range about 140°-190° 65 ethyltoluene ------10 1. Trimethylbenzene (e. g., mesitylene).------45 Solves.so 100 (boiling point range about 150°-180° C.) 2. 155 Tetramethylbenzene ------40 30 Solves.so 150 (boiling point range about 180°-215 C.) -- 170 ------5 A neutral coal tar distillate having a boiling range between Examples of materials coming from the distil SES130-210° ,C. and comprising atetramethylbenzenes, mixture of alkylated and benzenes, methyl ethyie.g. lation of light petroleum oils comprises liquids eZeeS. Mixture of aromatic hydrocarbons comprising xylene, trimethyl identified as SolveSSOS which have boiling point 35 benzene, tetramethylbenzene, and closely related alkylated benzenes ranges somewhere between approximately 94° C. lined by cracking and hydroforming of sciect petroleum oil frac to 240° C., and Solvent naphtha, which is a nar roW cut boiling betWeen about 135° C. to 155° C. Although the foregoing examples are all con Description of the above-described mixtures of cerned with making Solutions having a concen liquid alkylated aromatic hydrocarbons may be 40 tration of ten per cent, by Weight, of the poly found in the book “Industrial Solvents' by Ibert meric chlorotrifluoroethylene, it will, of course, Mellan, published by Reinhold Publishing Corp. be apparent to those skilled in the art that lower (1939) and the book "Protective and Decorative or higher concentrations of the polymer may also Coatings' edited by Joseph J. Mattiello, chapter be (imployed. Thus, 'I may prepare solutions 14B, page 180 and published by U. S. Printing 45 varying in Concentrations from about one to Office (1945). twenty per cent, by weight, of the polymer based It was entirely unexpected and in no way could On the total Weight of the solution. In such have been predicted that these particular aro cases where lower concentrations of the polymer matic hydrocarbons were effective solvents for are desired, it will be found that somewhat lower polymeric chlorotrifluoroethylene since similar 50 temperatures of Solution will be encountered solvents such as, , 1,2,3-trimethylbenzene, while the converse, that is, somewhat higher tem ethylbenzene, n-butylbenzene, diethylbenzene, peratures of Solution may be needed when the etc., were entirely ineffective as solvents for the concentration of the polymer rises substantially polymer. above ten per cent. The advantage of the aforementioned solvents 55 In addition to the requirement for higher in Combination with the polymeric chlorotrifiu Solution temperatures where concentrations Oroethylene for making solutions lies in the fact greater than ten per cent of polymer are de that it is poSSible to obtain solutions of the sired, it will also be noted that the viscosity of polymer at relatively low temperatures. Because the solution will begin to increase materially, of this there is Scarcely any change in the proper However, in many instances this disadvantage can ties of the polymer due to high temperatures as 60 be cured by raising the temperature of the solu quite frequently occurs when solvents having a tion (if the solvent permits this) to a point where relatively high Solution temperature are employed a satisfactory viscosity is attained. All these fac for making the solutions of the polymer. More tors which have been mentioned above can be over, because the aromatic hydrocarbons men 65 balanced to give solutions of polymeric chloro tioned above do not become peroxidized readily, trifluoroethylene which have satisfactory con oxidative effects on the polymer are minimized. centration of polymer, viscosity, and operating In order that those skilled in the art may bet temperature range. ter understand how the present invention may be The claimed Solutions have utility in many practiced, the following example is given by way applications and may be employed in various of illustration and not by Way of limitation. 70 ways. They may be used to coat and impregnate various fillers, such as, for example, glass cloth, EXAMPLE 1. glass batting, asbestos cloth or asbestos floats, This example illustrates the preparation of mica, etc. In addition, the solutions are advan Solutions of polymeric chlorotrifluoroethylene 75 tageously employed for coating electrical con 2,542,070 ductors to give heat resistant and chemical re meric chlorotrifluoroethylene containing at least sistant insulations for such conductors. If de one per cent, by weight, of the polymer, which sired, molding compositions may be advantage method comprises (1) forming a mixture of in Ously prepared by adding various inorganic gredients comprising (a) finely divided polymeric fillers to obtain a homogeneous mixture and chlorotrifluoroethylene and (b) an aromatic hy thereafter removing the solvent from the mix drocarbon selected from the class consisting of ture. Laminated products may also be prepared pseudocumene, mesitylene, tertiary-butylbenzene, by coating and impregnating sheet material with p - tertiary - butlytoluene, beta - methylnaph the Solutions and Superposing layers of the in thalene, alpha,beta-dimethylnaphthalene, amyl pregnated and coated material and pressing the O biphenyl, alpha - methyl, para - methylstyrene, total assembly under heat and pressure (after para-cymene, distyrene, diamylbiphenyl, para the solvent has been removed from the treated ditertiary-butylbenzene, mixtures of alkylated sheet material), thereby to cause fusing of the benzenes obtained from coal tar distillates and polymer and to give a homogeneous article. from select petroleum fractions, and mixtures of What We claim as new and desire to secure 5 the foregoing ingredients, and (2) heating the by Letters Patent of the United States is: mixture of ingredients at an elevated tempera 1. A Solution comprising (1) a solute phase ture sufficient to dissolve the polymer and to form a homogeneous solution. comprising polymeric chlorotrifluoroethylene dis 8. The method of forming a solution of poly solved in (2) a solvent phase comprising an aro meric chlorotrifluoroethylene containing at least matic hydrocarbon selected from the class con 20 one per cent, by weight, of the polymer, which sisting of pseudocumene, mesitylene, tertiary method comprises (1) forming a mixture of in butylbenzene, p - tertiary - butyltoluene, beta gredients comprising (a) finely divided polymeric methylnaphthalene, alpha,beta-dimethyl naph chlorotrifluoroethylene and (b) mesitylene, and thalene, amylbiphenyl, alpha - methyl - para (2) heating the mixture of ingredients at in methylstyrene, para-cymene, distyrene, diamyl 25 elevated temperature sufficient to dissolve the biphenyl, para-ditertiary-butylbenzene, mixtures polymer and form a homogeneous solution. of alkylated benzenes obtained from coal tar dis 9. The method of forming a solution of poly. tillates and from select petroleum fractions, and meric chlorotrifluoroethylene containing at least mixtures of the foregoing ingredients. one per cent, by weight, of the polymer, which 2. A Solution comprising (1) a solute phase 30 method comprises (1) forming a mixture of in. comprising polymeric chlorotrifluoroethylene dis gredients comprising (a) finely divided polymeric Solved in (2) a solvent phase comprising mesi chlorotrifluoroethylene and (b) p-tertiary-butyl tylene. benzene, and (2) heating the mixture of ingre 3. A Solution comprising (1) a solute phase dients at an elevated temperature sufficient to comprising polymeric chlorotrifluoroethylene dis 35 solved in (2) a solvent phase comprising para dissolve the polymer and form a homogeneous tertiary-butyltoluene. solution. 4. A Solution comprising (1) a solute phase 10. The method of forming a solution of poly comprising polymeric chlorotrifluoroethylene dis meric chlorotrifluoroethylene containing at least solved in (2) a mixture of aromatic hydrocar one per cent, by weight, of the polymer, Which bons comprising , methyl ethyl benzenes, 40 method comprises (1) forming a mixture of in trimethyl benzenes and tetramethyl benzenes. gredients comprising (a) finely divided polymeric 5. A solution comprising (1) a solute phase chlorotrifluoroethylene and (b) a mixture of aro comprising polymeric chlorotrifluoroethylene dis matic hydrocarbons comprising xylenes, methyl solved in (2) tertiary-butyl-benzene. ethyl benzenes, trimethyl benzenes and tetra 6. A solution comprising (1) a solute phase 45 methyl benzenes, and (2) heating the mixture comprising polymeric chlorotrifluoroethylene dis of ingredients at an elevated temperature suf solved in (2) an organic liquid comprising a ficient to dissolve the polymer and form a homo mixture of alkylated benzenes obtained by the geneous Solution. hydroforming and distillation of select petroleum MURRAY MI, SPRUNG. oil fractions and having a boiling point range 50 FREDERICK O. GUENTHER. of from about 150° to 215 C. 7. The method of preparing a solution of poly No references cited.