US3089849A

US3089849A - Coating and lubricating composition

Info

Publication number: US3089849A
Application number: US852941A
Authority: US
Inventors: Donald H Linson
Original assignee: Individual
Current assignee: Individual
Priority date: 1959-11-16
Filing date: 1959-11-16
Publication date: 1963-05-14
Anticipated expiration: 1980-05-14

Description

3,089,849 CQATENG AND LUBRICATHNG CGMPGSl-TEUN ll ronald H. Linson, Mansfield, Ohio No Drawing. Filed Nov. 16, 1959, Ser. Flo-852,941 '7 Claims. (Cl. 252-29) The present invention relates generally to the coating art and is more particularly concerned with novel brushing compositions and with coatings obtainable from these compositions which are dry, tough, hard and wearand weather-resistant and which have cold metal lubricity and which combine electroconductivity and superior physical characteristics.

This application is a continuation-in-part of applicatron Serial No. 554,108, filed December 1, 1955, entitled Coating and Lubricating Composition now abandoned.

The coating field is old, crowded and highly specialized and complex as a result of efforts to solve the wide varrety of problems arising from related fields and arts. As applied to the lubricating art, for example, the continuing development of machines has demanded new and better lubricants and lubricating methods and this has led more recently to rapid development and growth of solid lubricants as a separate art. The present status of solid lubricants attests to the fact that considerable success has been realized in meeting lubrication problems along this line. Nevertheless, there has persisted all through this development, an urgent need for a lubricant which would be effective over long periods of time to lubricate railway switch plates and which would also be easy to apply and inexpensive to use.

The railway switch plate lubrication problem is an uniquely difficult one in the lubrication art because of the highly variant conditions to which the lubricant may be subjected in normal use. The combination of adverse weather conditions, large quantities of highly abrasive material and the large proportion of exposure of lubricated surfaces, makes the use of heavy oils or greases for this purpose impracticable. Wet oil and grease will quickly collect dust, grit and sand blown about by a wind or passing trains so that frequent cleaning and weekly treatment with fresh lubricant is required to maintain the par-ts in good operating condition. Heavy rainfall floats away the greases, necessitating lubrication of the parts after each shower.

At the same time, there has existed another hitherto unsatisfied and urgent need for a substance which could be applied to trolley wires to provide lubricating characteristics without adversely effecting electrocon-ductivity and which would, in addition, have good life characteristics.

in another branch of the coating art which is unrelated to lubrication problems, there has in recent times developed an important demand for a coating composition combining the characteristics of tenacious adherence to glass-like surfaces with electrical conductivity and freedom from arcing or flashover tendencies. Such a coating would satisfy the principal requirements for television picture tube coating compounds and if, in addition, it were easy to apply regularly and uniformly and were inexpensive to make and use and had good life character- ..istics, it would constitute a valuable addition to this branch of the coating art.

By virtue of the present invention which is predicated on my surprising discoveries as set forth below, solutions to the foregoing problems are provided. At the same time, new tools are made available for use by those skilled in the art in meeting and disposing of other coating problems and lubricating problems and for other problems which may not be directly related to those specifically set forth above.

attests Patented May 14, 1%63 ice Novel compositions of this invention in the form of coatings are dry and non-tacky and yet are highly effective in lubricating metal parts such as switch plates and trolley wires having good cold metal lubricity and wearand weather-resistance. Furthermore, these coatings will tenaciously adhere for protected periods over wide varieties of surfaces including metal, wood, glass and plastics.

Still further, the brushing compositions hereof are easily prepared and applied and are composed of inexpensive substances so that the use of these compositions holds a net substantial economic advantage over other materials for the same purposes in the prior art and on the market today. No special skill or tool is required in applying these brushing compositions, there being no baking necessary. Also the time factor involved in providing coatings of this invention through the use of these brushing compositions is not significant, being on the order 'of a few minutes under normal temperature conditions.

Underlying this invention are my discoveries that the foregoing problem can be solved and the additional advantages stated above can be obtained through the use of a particular kind of graphite having particular size ranges. Also, I have found that the ratio of resin to graphite is broadly critical so that the superior physical characteristics of the lubricating compositions of this invention may be obtained. Still further, I have found that f urfural exhibits surprising and beneficial influence upon the tenacity of these coatings in addition to acting as a wetting agent for the graphite during compounding and as a plasticizer for the resin body. Still further, -I have found that certain proportions of the ingredients produce a composition which has a relatively long life when used purely as a lubricant for mechanically moving parts, and that that same composition displays desirable current carrying characteristics when used as a conducting film where no lubricating qualities are required A similar composition, however, of dilfer-ent proportions as set forth hereinafter, displays good life characteristics when used in applications in which there is relative movement of mechanically bearing parts together with current flow between the parts, and with relatively poorer characteristics where only the lubrication or current carrying functions are performed alone and not in combination.

In particular, I have found that the graphite employed must be natural crystalline flake graphite ranging in size fnom about one-tenth to ten microns.

The resin component of these compositions must be in the amount of one part of resin to 1.8 parts of graphite with the ratio range of these ingredients being between about one part of resin to 1.5 parts of graphite and one part of resin to 2.1 parts of graphite. Furthermore, the resin must be one which will air-dry under practically any outdoor temperature condition within one hour to provide a dry, tough and hard coating as stated above.

The amount of solvent employed in preparing the brushing compositions of this invention appears to have an important bearing upon the nature of the coatings ultimately produced. Thus, where the only seemingly important difference between two brushing compositions of this invention is the relative amount of solvent, wear characteristics under conditions of heavy current flow in the finished coatings will be practically opposites. The thin brushing composition, as will hereinafter be more particularly described, displays strong resistance to physical wear under continuously heavy current flow but surprisingly does not wear well under the same circumstances except for current flow. Conversely, the higher concentration composition subsequently to be described in detail, produces a coating which will wear well in the absence of heavy current flow but is subject to rapid erosion and destruction when the current factor is introduced.

A brushing composition of this invention, generally described, comprises natural, crystalline flake graphite, coumarone-indene resins and a solvent for the resins in an amount suflicient to dissolve and maintain in solution all the resins in the composition, the graphite and resins being proportioned according to my discoveries to provide coatings which are dry, tough, hard and wearand weather-resistant and which have cold metal lubricity.

In addition, this brushing composition will normally preferably include a combination wetting agent effective to wet the graphite and drying oil for the blending of the resins. Also, usually preferably, it will include a plasticizer, suitably furfural, in amounts sufiicient to impart the desired qualities to the coating to be produced through While as a general proposition, furfural is not an essential ingredient in the compositions of this invention, it has certain properties in these compositions as indicated above which make its use especially desirable in most cases. Particularly, furfural serves as a wetting agent for the surface of the part to which the brushing composition is applied so that the compound may be more effectively distributed over the surface of the part, and in more direct contact therewith; so that the resulting film which is formed after drying adheres to the part more tenaciously than would otherwise be the case. Additionally, furfural acts to some extent as a wetting agent for the use of this composition, making them tough and wear resistant and preventing them from becoming brittle and from being subject to chipping or scratching tendencies.

In terms of ranges of proportions of these various ingredients the graphite will amount to between about 60 parts and about 70 parts in these compositions. coumarone-indene resins will amount to between about 40 parts and about 50 parts. The wetting agent and the furfural then will each be present in an amount between about parts and about parts. The proportion of solvent employed is, as indicated elsewhere herein, not sharply critical in terms of the kind of coating obtained, but this factor does seem to exert an effect where a large difference exists. Generally the solvent will be present in amounts varying between 300 and 700 parts. However, it is clear that while the coatings are quite different,

their utility is not lost and the novel advantages of this invention are realized at the extremes of solvent proportions.

A preferred brushing composition of this invention contains about 66 parts of natural crystalline graphite in flake form as described above and about 44 parts of c0umarone-indene resins of the type described. In addition, it contains about 14 parts of furfural and about 14 parts of the said combination wetting agent and a drying oil. The solvent employed in this composition is 1,1,1- trichloroethane which is in sufficient quantity in the composition so that the resins, furfural Wetting agent are all contained in solution and the composition is of good brushing consistency.

As those skilled in the art will understand, other resins may be employed in the preparation of these brushing compositions of this invention, it being necessary that these equivalent resin materials be of physical characteristics substantially the same as or closely similar to the coumarone-indene resins hereinbefore described. Thus, for example, resins which are not capable of air-drying under normal ranges of outdoor temperature to produce the kind of coatings described above and hereinafter will not be satisfactory for general outdoor use in accordance with this invention unless these resins can be modified through-the use of accelerators or other substances which are effective to alter their drying characteristics or other properties to remove deficiencies which would disqualify them for use in this invention. Likewise, where indoor uses are contemplated, the selection of the resin ingredient should be made with regard to its drying or setting characteristics under room temperature and humidity conditions. Examples of particular resins which may be employed in place of the coumarone-indene resins include cellulose acetate, shellac and polystyrene.

Where all or part of the coumarone-indene content is substituted by one or more of these resins or their equivalents, it will, nevertheless, be necessary to observe the critical ratio and relationship existing between the graphite and resin constituents of these invention compositions in order to obtain consistently the new and important advantages set forth above.

the graphite particles themselves and as a plasticizer for the resins to prevent excessive hardening and chipping of the coating after the film has dried.

Insofar as its plasticizing effect is concerned, it will be apparent to those skilled in the art that there are various substances equivalent to furfural for compounding these invention compositions and that where all or part of the coumarone-indene resin content is substituted with another resin or resin mixture, another plasticizer may be used. Likewise, it will be obvious to those skilled in the art that the amount of that plasticizer may vary from the proportion stated hereinabove in reference specifically to furfural according to the effectiveness of the plasticizer substance selected and the nature of the resin or resin mixture used. Thus, in an extreme case, for example, where the resin is of the polyethylene type and, therefore, self-plasticizing, it is theoretically possible that no plasticizer will be required in compounding compositions of this invention including such a resin. The use of such a self-plasticizing resin or resins requiring lesser or greater amounts of furfural or other plasticizers than the coumarone-indene resin is, however, within the spirit of this invention and is contemplated by the appended claims hereto.

Concerning the combined wetting agent and oil, it is my preference to use a wetting agent known in the trade as Selectol (proprietary name) which is a processed oil derived from sardine or herring oil. As stated, this substance has the unique ability to act as a wetting agent in the composition and also as a drying oil to promote the blending of the coumarone-indene resins. Here again, it is apparent that other substances may be employed for these same purposes although it may be necessary to use two different substances to obtain this combination effect. Other drying oils such as tung, linseed, soya bean and menhaden oil and certain non-drying oils such as, for example, polymerized Selectol can advantageously be used. However, to promote the oxidation of a drying oil, a conventional drier, such as one containing lead or cobalt, may be employed. As examples of wetting agents suitable for this purpose, there are dioctyl sodium sulfosuccinate, glyceryl (mono) laurate and certain silicones.

The amounts of wetting agents and drying oils or combination substances incorporated in the brushing compositions of this invention may be varied to satisfy the requirements of the user and according to the nature of the resinous material employed as the film forming base of the mixture.

While I have indicated above that trichloroethane is preferred as the solvent for these brushing compositions, it is possible to obtain consistently the new and desirable results of this invention through the use of other solvents.

50% naphtha and 50% perchlorethylene gives excellent results in this use and I have been able to detect no differences in the wearing qualities of the coating produced through the use of brushing compositions incorporating this solvent and those incorporating trichloroethane. Where flame for fire preventiveness is a desired characteristic in these compositions, I have successfully employed an inhibited grade of 1,1,1-trichloroethane. While other solvents or mixtures of solvents may be employed in compounding the coumaronedndene resin base compositions hereof, it will be apparent that where other resins are employed in place of the coumarone-indene type as described above, still other solvents and mixtures of solvents may be used for this purpose.

As a dry film or coating or deposit, the compositions of this invention contain substantially no solvent for the resins but incorporate all the original graphite and coumarone-indene resins originally present in the brushing composition and the graphite is substantially uniformly dispersed throughout the resin body. Thus, the ratio of graphite and resins is maintained or carried over from the brushing composition to the finished coating. Likewise, these novel coatings will preferably include the drying oil and furfural in substantially the proportion of these substances in the brushing composition.

The beneficial results of the invention are achieved by the use of flake graphite in which the particles are substantially in the size range from one-tenth microns to ten microns. However, the size distribution may vary considerably.

The invention has been practiced with natural, flake graphite ranging in size from one to ten microns, but in which the average size of the particles was about five microns as determined by direct microscopic examination. A substantial proportion of the particles were in the size range from four to six microns, the graphite having been processed by a fluid energy reduction mill.

The invention has been practiced with natural, flake graphite produced by the Southwestern Graphite Company and known as Grade No. 1650 Microcrystalline Graphite. An estimate of the particle size distribution of that graphite, obtained by direct microscopic examination, is as follows:

Microns Average largest 10-12 Slight trace 10-30 53-10% 5-10 ll5% 2 5 20-25% 1- 2 25-30% .5- 1 3035% .1-.5

This graphite contained no detectable quantity of nongraphitic carbon or amorphous graphite. The viscosity, as measured by the Brookfield Synchro-Lec Viscometer, Model RVF, was between two thousand and two hundred centipoises.

The graphite above referred to is ground by a fluid energy mill and has an average particle size of about seven-tenths micron, as measured by the Fisher Sub- Sieve Sizer. This method of determining average particle size is described, for example, in a paper titled Measuring Average Particle Diameters and Powders by E. L. Gooden and C. M. Smith in Industrial Engineering Chemistry Analysis Edition, volume 12 (1940), pages 479 to 482, and in United States Patent 2,261,802, issued November 4, 1941, to E. L. Gooden.

Graphite useful in practicing the invention is referred to herein as natural crystalline flake graphite having a size range from one-tenth to ten microns as described above. Graphite in which substantial proportions of the particles are in size ranges above ten microns are unsatisfactory for the reasons that the particles are not maintained in suspension and a uniform coating of good lubricity cannot be obtained. Thus, for example, utilization of natural crystalline flake graphite particles of about twenty-five microns, average size, in compositions otherwise the same as those described herein resulted in a high degree of separation of the graphite from the carrier.

To further acquaint those skilled in the art with the nature of the present invention, the following illustrative, but not limiting, examples are offered.

Example 1 In preparing a brushing composition, 44 pounds of cournarone-indene resins of melting point temperatures between about 200 F. and about 225 F. were introduced onto a mixing vessel and 32 gallons of 50-50 mixture of perchlorethylene and naphtha were added and mixed with the resins until all the resin charge was dissolved. Furfural and raw Selectol, in the amount of 14 pounds each were then added and mixed into the solution. As the final step, 66 pounds of five-micron graphite was added to the solution and mixed therewith until a homogeneous mixture was obtained. In this mixing operation, care was exercised to insure that none of the resin charge remained undissolved.

This brushing composition was used to provide a lubrieating coating on a railway switch plate in place and use in a railway track installation in northwestern Ohio in the summer season. In this application, the switch plate surface Was carefully cleansed to remove dirt and residual grease from previous lubricating operations and then washed with a 50-50 mixture of perchlorethylene and naphtha and burned with a pressure torch and then carefully brushed with a clean brush in accordance with standard painting or rust prevention practice. The brushing composition was then applied with a brush to the cleaned switch plate surface and permitted to dry for approximately 15 minutes at which time the coating was dry to the touch. This finished coating had a dark appearance attributable to its graphite content and displayed good cold metal lubricity comparable to a freshly oiled or greased switch plate surface and yet was nontacky, dry, tough and relatively hard and quite Wearand weather-resistant being employed in regular use for a sixmonth period without apparent loss of its lubricating qualities and without any breaks appearing in its surface.

Example 2 Another brushing composition was prepared by mixing 44 pounds of coumarone-indene resins of the aforesaid 200 F. to 225 F. melting point temperature with 32 gallons of 1,1,1-trichloroethane (Dow Chemical Companys Chlorothene) to produce a solution containing the entire resin charge. Furfural and resin (Selectol) in the amount of 14 pounds each, were then mixed into the solution. As a final step 66 pounds of five-micron graphite was added to this solution and thoroughly mixed therewith to produce a homogeneous mixture. This composition was employed to provide a coating on the glass surface of a television picture tube. This surface was first prepared by cleaning to remove dirt and oil films and then the brushing compound was applied to the portion of the glass surface to be coated. The application of the brushing composition to the tube was made under room temperature conditions so that the resulting coating was dry to the touch within a matter of about ten minutes. On inspection, the coating appeared uniform and continuous and on subsequent tests, proved to have the requisite conductivity to maintain stable operation of the picture tube without arcing or flash-over.

Example 3 Another brushing composition was prepared by mixing 21 pounds of coumarone-indene resins with 32 gallons of solvent comprising a S050 mixture of perchlorethylene and naphtha and mixed until the resin charge was dissolved. Furfural in the amount of seven pounds and Selectol in the amount of six pounds were then added and mixed into the solution. As a final step, 33 pounds of five-micron graphite was added to the solution and mixed therewith to produce a homogeneous mixture. This composition was employed to provide a lubricating and electroconductive coating on a trolley Wire which was first thoroughly cleaned to remove all dirt and films. The composition was applied to the trolley wire at room temperature and the composition dried quickly and produced a uniform hard coating.

This composition displayed excellent lubricating and electroconductivity characteristics for trolley currents in the order of 500 to 1000 amperes, and resulted in excellent life characteristics for the coating and for the current collector. However, it was found that the composition prepared according to this latter formula had a much shorter life when applied to bearing surfaces in which no current was flowing, than did the composition prepared as set forth cither in Example 1 or Example 2. Also, compositions prepared according to Examples 1 and 2 displayed a life of from 10 to 100 times that of the composition of Example 3 when used to form a lubricating coating between relatively moving parts in which there was no current flowing.

When utilizing the Grade No. 1650 Microcrystalline Graphite in the brushing compositions of Examples 1 and 2, the quantity of graphite may be increased to about 76 pounds, other proportions being the same. The viscosity of the mixture should be in the range from about two thousand to four thousand centipoises, whatever the size range of the graphite particles. In the brushing composition of Example 3, the quantity of graphite is increased to about 38 pounds for the Grade No. 1650 Graphite.

Where ratios, parts, or percentages are stated herein and in the appended claims, reference is made to the weight basis rather than the volume basis.

Having thus described the present invention so that others in the art may be better able to understand and practice the same, I state that what I desire to secure by Letters Patent is defined in what is claimed.

What is claimed is:

1. A composition of matter capable of being converted into a hard, tough, electrically conductive, matrix bonded, lubricant coating on a base article comprising:

(a) a substantially uniform mixture of natural, crystalline, flake graphite particles, substantially all of which range between about micron and about 10 microns in size as measured by direct microscopic examination,

(b) a matrix material selected from the group of substances consisting of coumarone-indene resins melting at temperatures between about 200 F and about 225 F., cellulose acetate, shellac, polystyrene and polyethylene, the graphite being present in amounts between about 60 parts and about 70 parts and the resins being present in amounts between about 40 parts and about 50 parts,

() about 14 parts of furfural,

(d) between about 300 parts and about 700 parts of a solvent for said resins selected from the group consisting of trichlorethane and a mixture of naphtha and perchlorethylene,

(e) and about 14 parts of a combined wetting and drying agent selected from the group consisting of sardine oil, herring oil, tung oil, linseed oil, soybean oil and menhaden oil.

2. A composition of matter capable of being converted into a hard, tough, electrically conductive matrix bonded, lubricant coating on a base article comprising:

(a) a substantially uniform mixture of natural, crystalline, flake graphite particles, substantially all of which range between about 1/ 10 micron and about 10 microns in size as measured by direct microscopic examination,

(b) a matrix material consisting of coumarone-indene resins melting at temperatures between about 200 F. and about 225 F., the graphite being present in amounts between about parts and about parts and the resins being present in amounts between about 40 parts and about 50 parts,

(c) about 14 parts of furfural,

(d) between about 300 parts and about 700 parts of a solvent for said resins consisting of trichlorethane,

(e) and about 14 parts of a combined wetting and drying agent consisting of sardine oil.

3. The composition of matter specified in claim 1 in which the solvent for the resins consists of a mixture of naphtha and perchlorethylene.

4. The composition of matter specified in claim 1 in which the combined wetting and drying agent consists of herring oil.

5. The composition of matter specified in claim 1 in which the matrix material consists of polyethylene in amounts up to about 40 parts.

6. The composition of matter specified in claim 1 in which the graphite particles range in size from about 1 micron to about 10 microns.

7. A brushing composition for providing a lubricating coating by drying in open air, which comprises about 66 parts of natural, crystalline graphite in the form of flakes ranging in size from one micron to ten microns, about 44 parts of coumarone-indene resins having incipient melting point temperatures between 200 F. and about 225 F., about 14 parts of furfural, about 14 parts of a drying oil for blending of said resins selected from the group consisting of sardine oil, herring oil, tung oil, linseed oil, soybean oil and menhaden oil, and between about 300 parts and about 350 parts of a solvent for said resins, the said solvent being 1,1,1-trichlorethane all with the graphite in uniform suspension therein.

References Cited in the file of this patent UNITED STATES PATENTS 1,185,682 Kirkegaard June 6, 1916 1,967,088 Geyer July 17, 1934 2,731,371 Ramadanoff Jan. 17, 1956 OTHER REFERENCES Scientific American, May 1939, page 314.

Neville: Resins and Plasticizers, pages 5-9, 37-52, 59, and 64, The Neville Co., Pittsburgh, Pa., 1945.

Claims

1. A COMPOSITION OF MATTER CAPABLE OF BEING CONVERTED INTO A HARD, TOUGH, ELECTRICALLY CONDUCTIVE, MATRIX BONDED, LUBRICANT COATING ON A BASE ARTICLE COMPRISING: (A) A SUBSTANTIALLY UNIFORM MIXTURE OF NATURAL, CRYSTALLINE, FLAKE GRAPHITE PARTICLES, SUBSTANTIALLY ALL OF WHICH RANGE BETWEEN ABOUT 1/10 MICRON AND ABOUT 10 MICRONS IN SIZE AS MEASURED BY DIRECT MICROSCOPIC EXAMINATION, (B) A MATRIX MATERIAL SELECTED FROM THE GROUP OF SUBSTANCES CONSISTING OF COUMARONE-INDENE RESINS MELTING AT TEMPERATURES BETWEEN ABOUT 200*F AND ABOUT 225*F., CELLULOSE ACETATE, SHELLAC, POLYSTYRENE AND POLYETHYLENE, THE GRAPHITE BEING PRESENT IN AMOUNTS BETWEEN ABOUT 60 PATYS AND ABOUT 70 PARTS AND THE RESINS BEING PRESENT IN AMOUNTS BETWEEN ABOUT 40 PARTS AND ABOUT 50 PARTS, (C) ABOUT 14 PARTS OF FURFURAL, (D) BETWEEN ABOUT 300 PARTS AND ABOUT 700 PARTS OF A SOLVENT FOR SAID RESINS SELECTED FROM THE GROUP CONSISTING OF TRICHLORETHANE AND A MIXTURE OF NAPHTHA AND PERCHLORETHYLENE, (E) AND ABOUT 14 PARTS OF A COMBINED WETTING AND DRYING AGENT SELECTED FROM THE GROUP CONSISTING OF SARDINE OIL, HERRING OIL, TUNG OIL, LINSEED OIL, SOYBEAN OIL AND MENHADEN OIL.