US3506463A - Mold release agent - Google Patents

Description

United States Patent 3,506,463 MOLD RELEASE AGENT Rudolph J. Holzinger, Haddonfield, N.J., assiguor to Mobil Oil Corporation, a corporation of New York No Drawing. Filed Jan. 4, 1967, Ser. No. 607,159 Int. Cl. B28b 7/38; C10m /12, 1/24 US. Cl. 106-3824 9 Claims ABSTRACT OF THE DISCLOSURE A mold release agent, for use in metal casting operations, which comprises a major proportion of an oil of lubricating viscosity and minor proportions of a carboxylic acid having a molecular weight of at least about 200 and a dispersant for products which are formed during the casting operation.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to new and improved compositions possessing particular utility as mold release agents. More particularly, the invention relates to new and improved compositions having utility as mold release agents and which, in one aspect thereof, are particularly useful as mold release agents or lubricants in metal casting operations.

Description of the prior art During recent years, much effort has been devoted to the use of continuous casting, especially of steel, in place of conventional ingots. Continuous casting is defined as the making of a casting many times the length of the mold in which it is produced. From a pouring ladle, the molten metal is poured into a tundish and through heat resistant nozzles, into an open-bottomed mold of the desired shape. This mold is usually made from copper, frequently chrome-plated. By means of cold water ducts or chambers, the steel is cooled in the mold just enough to harden the exterior surface of the casting which forms a shell to hold the balance of the liquid metal. The partially solidified casting is then continuously withdrawn from the bottom of the mold. After further cooling, it may be cut to the desired length or rolled directly to its final shape.

In such casting or molding operations, the molded article or casting normally tends to adhere to the inner surface of the mold at the end of the operation by reason of the relatively high molding pressures employed. These pressures force the casting against the surfaces of the mold walls, making subsequent removal of the casting very difiicult. In order to facilitate the release of the casting, various mold release agents or lubricants have heretofore been employed. These agents, however, have not been found to be particularly satisfactory in metal casting operations. In these operations, it has been found that such materials as metal oxides, coke and slag are formed as products of the casting operation. More specifically, in using such mold release agents as various forms of vegetable oils, it has been found that the water content must be kept sufiiciently low in order to prevent the appearance of holes and voids. In some instances, it has also been found that the mold release agent may cause coke formation to occur on the mold wall, which tends to cause sticking of the solidifying metal. Furthermore, inclusion of accumulated slag or metal oxides on the solidifying metal surface may lead to breaks in the frozen skin and run-out of liquid metal.

SUMMARY OF THE INVENTION In accordance with the present invention, as more ful- 1y hereinafter described, there are provided new and improved compositions adapted for use as mold release agents in metal casting, which comprise a major proportion of an oil of lubricating viscosity and minor proportions of a carboxylic acid and a dispersant for products formed during the casting operation. These compositions, as also more fully hereinafter described, are markedly effective in permitting ease of removal of the formed casting; and the products formed during the casting operation, such as metal oxides, react with the carboxylic acid to form the corresponding soaps, While the dispersant serves to prevent the soaps and excess slag from forming undesirable aggregates. The casting thus produced is found to be free of holes and voids, with no break in the frozen skin or run-out of liquid metal.

DESCRIPTION OF SPECIFIC EMBODIMENTS The lubricating oil employed in the novel mold release agent is an oil of lubricating viscosity having a viscosity range of from about 40 to about 500 SUS 100 F., and preferably from about 40 to about SUS 100 F. Mineral oils, preferably naphthenic, are most desirable which are essentially non-coke forming at typical mold wall temperatures, such as, for example, from about 450 F. to about 500 F. This lubricating oil, as previously indicated, is present in major proportion in the mold release composition. From a practical standpoint, the oil is present in an amount from about 50 to about percent, and preferably from about 60 to about 90 percent, by weight, of the total weight of the composition, for optimum results.

The carboxylic acid component of the mold release agent has a molecular weight of at least about 200, and preferably from about 300 to about 450. Liquid carboxylic acids are preferred having molecular weights above about 300. Exemplary of such acids are unsaturated acids, such as erucic acid, having a molecular weight of 339, phenylstearic acid having a molecular weight of 361 and naphthenic acids having average molecular weights of 325 or 415. Examples of other suitable carboxylic acids include those derived from the oxidation of petroleum fractions which meet the above-described requirements, provided that the unoxidized portion or diluent oil can satisfy the requirements set forth above for the lubricating oil component. The carboxylic acid, as previously indicated, is present in minor proportion in the mold release composition. From a practical standpoint, the acid is present in an amount from about 1 to about 25 percent, and preferably from about 5 to about 20 percent, by weight, of the total weight of the composition, for optimum results.

The dispersant component of the mold release agent, as indicated above, is one which is capable of preventing metal soaps and slag, formed during the casting operation, from forming undesirable aggregates. Various fur and acid-forming constituents are preferred, including polymeric, non-metallic engine oil detergents. Exemplary of the dispersants which can be employed for this purpose are alkaline earth metal sulfonates, phenates, phenatesulfides and oil-soluble acylated nitrogen compounds. Non-ionic, oil-soluble dispersants, such as sorbitan monooleate, may also be employed. The dispersant, as previously indicated, is present in minor proportion in the mold release composition. From a practical standpoint, the dispersant is present in an amount from about 1 to about 25 percent, and preferably from about 5 to about 20 percent, by weight, of the total weight of the composition, for optimum results.

If so desired, a solid lubricant, preferably in finely divided form, may also be dispersed in the mold release composition to act as a lubricant or fluxing agent. Thus, these materials may be employed in the form of true solids, such as, for example, graphite, carbon black or molybdenum disulfide; or in the form of heat-softening materials, such as, for example, a polytetrafluoroethylene; or in the form of materials acting as fluxes for metal oxides, such as, for example, sodium aluminum fluoride or borax. This solid lubricant is present in minor proportion in the mold release composition. From a practical standpoint, the solid lubricant is present in an amount from about .05 to about percent, and preferably from about 0.5 to about 5 percent, by weight, of the total composition.

The following examples will serve to illustrate the preparation of the novel mold release agents of the present invention and their effectiveness when employed in metal casting operations.

Example I A mold release composition is prepared comprising, by weight: 85 percent of a transformer oil having a viscosity of 60 SUS 100 F., 8 percent erucic acid (molecular weight 339), and 7 percent of a non-metallic dispersant comprising an oil-soluble, acylated nitrogen composition prepared in accordance with the method described in US. Patent No. 3,219,666, issued Nov. 23, 1965.

Example II A mold release composition is prepared comprising, by weight: 83 percent of the transformed oil, 8 percent erucic acid and 7 percent of the dispersant, as was described in Example I, above. Also included in this composition is 2 percent, by weight, of graphite as a solid lubricant.

Example III A metal casting mold is employed which is equipped with an oil lubricator, so positioned that the multiple orifices of the lubricator are spaced around the circumference of the mold. The mold release lubricant composition prepared in accordance with Example I is permitted to run down the inside of the mold wall from the lubricator, and thereby being uniformly applied to the mold surfaces. The desired metal material is then subjected to the casting operation under the usual conventional molding conditions. Following the formation of the desired casting, it is found that the latter is easily separated from the mold without sticking and without exhibiting any breaks or voids in the frozen skin or runout of liquid metal. On a comparative basis, it is found that in employing the oil component alone, or even in admixture with either the acid or the dispersant, difficulty is encountered in removing the casting and also in obtaining a casting which is free from damage.

Example IV Repeating the casting operation as disclosed in Example HI, but employing the mold release lubricant composition prepared in accordance with Example II, it is found that the molded casting is easily separated from the mold without sticking and without exhibiting any breaks or voids or run-out of liquid metal. On a comparative basis, it is found that in employing the solid graphite lubricant alone, or even in admixture with either the oil component, or acid or the dispersant, difficulty is encountered in removing the casting and also in obtaining a casting which is free from damage.

Example V A mold release composition is prepared identical in all respects to that prepared in accordance with Example I, except a 300 SUS 100 F. oil is substituted for the 60 SUS 100 F. oil. The casting operation described in Example III is repeated, and on a comparative basis, as set forth in Example III, it is found that the casting is easily separated from the mold without sticking and without exhibiting any breaks or voids in the frozen skin or run-out of liquid metal.

Example VI A mold release composition is prepared identical in all respects to that prepared in accordance with Example II, except a 300 SUS 100 F. oil is substituted for the 60 SUS 100 F. oil. The casting operation described in Example III is repeated, and on a comparative basis, as set forth in Example III, it is found that the casting is easily separated from the mold without sticking and without exhibiting any breaks or voids in the frozen skin or run-out of liquid metal.

While preferred embodiments of the mold release compositions of the present invention, their production and practical application thereof have been described for purposes of illustration, it will be understood that various modifications and adaptations thereof, which will be obvious to those skilled in the art, may be made without departing from the spirit and scope of the invention.

I claim:

1. A composition adapted for use as a mold release agent in metal casting comprising a major proportion of a hydrocarbon oil of lubricating viscosity and from about 1 to about 25 percent, by weight, of each of an unsaturated aliphatic hydrocarbon monocarboxylic acid having a molecular weight of from about 200 to about 450 and sorbitan monooleate as a dispersant.

2. The composition of claim 1 wherein said lubricating oil is present in an amount from about to about 90 percent, by Weight; and said carboxylic acid and said dispersant are each present in an amount from about 1 to about 25 percent, by weight.

3. The composition of claim 1 wherein said lubricating oil is present in an amount from about to about percent by weight.

4. The composition of claim 1 wherein said lubricating oil has a viscosity of from about 40 to about 500 SUS F.

5. The composition of claim 1 wherein said lubricating oil has a viscosity of from about 40 to about 80 SUS 100 F.

6. The composition of claim 1 wherein said carboxylic acid has a molecular weight from about 300 to about 450.

7. The composition of claim 1 wherein said composition also contains a solid lubricant in an amount from about .05 to about 10 percent, by weight.

8. The composition of claim 7 wherein said solid lubricant is selected from the group consisting of graphite, carbon black, molybdenum disulfide, polytetrafiuoroethlene, sodium aluminum fluoride and borax.

9. The composition of claim 7 wherein said solid lubricant is present in an amount from about 0.5 to about 5 percent, by weight.

References Cited UNITED STATES PATENTS 2,334,158 11/1943 Von Fuchs et al. 25256 XR 2,825,947 3/1958 Goss 16473 (Other references on following page) 2,842,837 7/ 1953 Huet et a1. 252-25 XR OTHER REFERENCES 3,018,250 1/1962 Anderson et Davey: Boundary Lubrication of Steel, Industrial and 3,034,186 5/1962 Holshouser 164 73 Engineering Chemistry, vol. 42, N0. 9 (September, 1950), 3,040,396 6/1962 Hudson 164-73 1837 1841 3,052,936 9/1962 Hamilton 16473 5 L $1161" 1 DANIEL E. WYMAN, Primary Examiner 9 Norman et a 3,244,631 4/1966 Van Der Voort 25256 VAUGHN Asslstam Exammer 3,245,908 4/1966 Lowe 25257 XR 3,245,910 4/1966- Lowe 252 57 XR 3,305,484 2/1967 Orloff 252 57 10 252252956 3,328,299 6/1967 Morway et a1 252-56 XR 'zg gg UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3.5 3 3 Dated April 1 4, 197

Inventorfs) Rudolph J. Holzinger It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1-, line 45, after "weight" insert a period and cancel the remainder of the claim.

Column t, line 50, after "weight" insert and said carboxylic acid and said dispersant are each present in an amount from about 5 to about 20 per cent, by weight--.

SIGNED AND SEALUJ AUG 4 .197

( Attest:

mm: 2. sum, :13. Edw when commissioner of Patents Attesting Officer