US1638579A - Coating compositions - Google Patents

Description

Patented j. e,t192

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This invention relates to coating compositions, and its object is to produce a li uidcoating composition which may be rea ily applied toan article and baked thereon to 5 form a hard, tough, flexible and durable coating. v

In particular it is desired-to produce a liquid coating composition which is of such nature that itmay be rapidly baked one metallic article. such as an eleetricalconductor to form a hard enamel which *is" flexible and inert to solvents, and whichhas' good insulating properties v r In accordance with the general features of the invention, polymerized vegetable oil' is used as the basis of a liquid coatlng composition. The vegetable oils which have been found most suitable are those such as tung oil and castor oil whichhavetheprop' 0 erties of polymerizing and thereafter gelatinizing when heated. Such oils give the best results when polymerizedto a state ust short of gelatinization. To realize this state of polymerization, the oil maybe heated in the presence of some: 'embstanc'e, such g as,

rosin oil, which will delay or prevent its gelatinization as set forth in my copendin'g' application,' erial No. 633,322, filed April 19, 1923. Vegetable oils prepared in this; way may be spread upon a metallic article and baked thereon to form a hard, flexible insulating enamel. Inasmuch 'as a liquid coating composition prepared from vegetable oils alone is slow baking the polymerized oil is mixed with certain substances which will decrease the time required to bake it on a metallic article, and which will for this reason considerably reduce the cost which have been found most satisfactory for this purpose are certainresin glycerides. A ,resin such as Congo copalmight be used; but it has been found preferable to 4 use the glyceride of such a resin, both be:

a hard substance at a. temperature similar to that at :which vegetable oils are thus transformed, and because the glycerol constances which are'more inert chemically. As

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.such' gasses; as 1.

' that "certain to zized, liquid condition; One feature of the inventionficons'ists' during the bakin T e presence oft and baked" o article and baked.

of coating 'such' articles. The substances cause it may be transformed by heat into' verts the acid bodies ofthe resin into 'sub-' WYQ K -F @Q H N or s s me q v v etable Oils" gelatinize,.l*it. is; deslrabl'eto ad during he e r fi io of. he resin a substance such as rosin oil which- '55 will maintain the glyceride's in :an unge producing a liquid coating composition which contains a minimum amount of acid bodies likely to attack'the to, form inetallic'soa s; f w ese soaps tends-toma fe' the] coating less flexible, whenj'hea'ted "to '-'a" degree at which it has the nee inert.

'ness to solvents, p V Afterthe add'tion of the glycerid, thv mixture should be" heated over a period of tlme, and, solvents, added, if,necessary,'.iin. order that the resulting composition will" produceasmooth coating whe reapplied.to?-

the metallic article. The

composition'is then spread on the metallic Such 'a' composition ba esrapi y-..--at .a temperature similar to that at which vege-' table oil hardens', which is hard enough to withstand thejtreatment to which electricalconductors are normally subjected, which. 'has a tou hness greater than that of an enamel forme 'from' vegetable oil alone, which-is soflexible that V a wire coated therewith may besha 1y bent without cracking the.' enamel, an d which has good. insulating fproperties. .Furthermore, this enamelis very resistant to the solvent actionoffthe benzol or carbon tetrav chloride contained in cleaning fluids commonly used upon; enameled conductors of v the linseedoil in certain varnishes with which enameled conductors are often coated of the denatured alcohol used in shellacs, of the resin-rosin oil combinations or the parafin used in the melted moistnre-proofin compositions with which coils of enamele wireare often impregnated, or of the gase line or: benzene contained in various liquids me allic article H and forms-Y'anenamel processes are given below to enable thein-Q vention to be more readily practiced. When proportions are given they are by weight" unless otherwise stated.

Tun oil (Chinese wood oil) is treated in any 0 the following ways:

(a) Equal parts of-tung oil and IOSlIl 011 are mixed and the mixture heated at a temperature between 210 C. and 220 C. for about two hours.

A glyceride of Congo copal is formed 1n any of the following ways:

(a) Two or more parts of ros1n 011 (preferably having a high boiling point) are added to one part of Congo copal and the mixture heated at between 275 C. and 300 C. for two hours or until the copal is entirely fused. One gallon of glycerol for each fourteen pounds of Congo copal is then added to the mixture and the temperature maintained at between 280 C. and 300 C. for about one hour. At the completion of this heating, the mass will still contain a considerable amount of uncombined copal and the above treatment with glycerol is reeated until the acid number of the mixture is reduced to about 10. If apparatus is used which will prevent to a certain extent the volatilization of the glycerol, all the glycerol may be added at once. During the treatment with glycerol the proportions of rosin oil to the copal should be maintained at not less than two to one.

(6') Congo copal is fused until it has lost twenty percent to thirty-five percent of its weight. To one part of this fused copal is added two parts of rosin oil. Glycerol is then added, and the process continued in either of the ways indicated in (a') above.

(0) Congo copal is fused with an e ual proportion of rosin, the resultant pro uct heated with glycerol, preferably in the presence of rosin oil and the process continued as in (a') above.

((2') Three parts of Congo copal are fused as described in my Patent 1,422,861 of July 18, 1922, with two parts of those fatty acids derived from tung oil by saponification. Sufficient glycerol to neutralize both the resin and the fatty acid is then added and the mixture heated, preferably in the presence of rosin oil, in the manner described in (a) above. A certain amount of tung oil is formed from the glycerol and the tung oil fatty-acids and is polymerized by the heating. 1,

The tung oil prepared as in (a), above is then mixed with the resin glyceride as in one of the foregoing examples in approximately the following proportions:

Four parts of treated tung oil to one part of resin glyceride prepared as in (a), (b'),

or Sf) T ree parts of treated tung oil to one part of the mixture o'f resin glyceride and six hours, when a suitable proportion of volatile solvent such as benzine or Hi-flashnaphtha is added. This composition is applied to the article to be coated and is baked thereon at or about a temperature of about300 C. to drive off the benzene or naphtha, any excess of lycerol, and the rosin oil, and to harden t e coating. If a thicker coating is desired, the application and baking of the composition may .be repeated as manytimes as necessary.

Any substance which will erform a like function should be considere as the equivalent of any of the substances mentioned in the specific examples described above.

Castor oil, corn oil, soya bean oil, rapeseed oil, sesame oil, cottonseed oil and peanut oil, for instance, may be used in place of either the tung oil or the linseed oil and either of these two oils may replace the other. Other resin oils may be used in place of the rosin oil.

Manila copal and shellac are examples of other resins which will form gelatinizable esters with glycerol and are best adapted for use in this invention.

The term gelatinization as used herein is intended to describe the sudden thickening that occurs when vegetable oils or resin glycerides are polymerized beyond a certain degree by heat, as contrasted with the very gradual thickening which occurs during the precedin polymerization.

What 1s claimed is:

1. The process of forming an insulating enamel which comprises heating gelatinizable vegetable oil inthe presence of a substance which will delay the gelatinization thereof, heatin together a resin, resin oil and lycerol mlxing the products so formed, heatmg the resulting mass and diluting the mass with a volatile material.

- 2. The process of forming a liquid coating composition which com rises heating tung oil with a mixture 0 glycerol and resin oil, heatin glycerol with a mixture of Congo copal and resin oil, mixing the products so formed and heating the mixture.

3. The process of producing a 1i uid coating composition which comprises eating a mixture of tung oil and resin oil with a quantity of glycerol less than said tung oil and mixing therewith a resin glyceride.

4. The process of forming a liquid coating composition which comprises heating a mixture of resin oil and gelatinizable vegetable oil, mixing therewith a substance to give a quick baking quality to said coating composition, and heatmg the mixture.

5. The process of forming a liquid coating composition which comprises neutralizing the acid bodies of a substance having a quick baking quality with glycerol, heating a mixture 0 gelatinizable vegetable oil and resin oil, mixing the product so formed, and

heating the resulting mixture.

6. The process of producing a liquid coating composition which comprises heating resin and resin oil, adding thereto sufficient glycerol to produce a glycerol ester of said resin having a loW acid number, and heat- 10 in the resulting mixture, heating gelatinizab e vegetable oil in the presence of resin oil, mixing the product so formed, and heating the resulting mass.

In witness whereof, I hereunto subscribe my name this 11 day of December, A. D. 1923.

CARL D. HOCKER.