US2875082A - Pour depressed microcrystalline wax - Google Patents

Description

2,875,082 PoUn nnrnnsssn WCROCRYSTALLINE wax John D. Tench, Prospect Park,

. Pa., assignor to Sun Oil Philadelphia,

Company, .Pa., a corporation of New Jersey No Drawing. Application July 18, 1955 r 1 Serial N0. 522,830 7 1 Claims. (CL 106-270) This invention. relates to wax compositions, and is more particularly directed to microcrystalline waxeshavmg a minor quantity of a pour depressant incorporated therein.

Microcrystalline waxes derived from petroleum are well known tempts have been made to surface of the mold in turn impresses a wrinkled surface on the metal or metal alloy cast thereon. The resulting metal casting must then surface. n

An object of the present invention is to provide a new microcrystalline wax composition. Another object is to provide a microcrystallinewax composition especially suitable for use in producing molds which can be used for the precision casting of metal articles. Other objects will be apparent from the following specification.

It has now been found that the incorporation ofa minor. quantity ofv a wax of petroleum origin yields a microcrystalline. wax compositionwhich achieves the above and other objects. Thus, the microcrystalline wax vention form a smooth, wrinkle-free surface when solidified from :themoltenstate. The resulting smooth surface renders t he new Waxcornpositions; especially suitable for the preparation of m M ing tif metal articles. Since the surface imparted to the mold by the-wax is smooth,.the surface of the resulting metal casting issmooth and does not require machining.

By pour depressant, as used herein, is meant a material which, when added in minor quantity to a lubricating oilhaving a relatively high pour point, such as a paraffinic lubricating oil, substantially reduces the pour point thereof. The pour point of an oil indicative of the lowest temperature at which it can be poured from a container, and can be determined by ASTM Method D97-47.

Microcrystalline waxes which can be used to prepare the compositions of the invention are derived from the heavy fractions of petroleum, residual fractions producing especially suitable waxes. The microcrystalline waxes which can be used should have a melting point of at least 135 F., andpreferably of at least 150 F., say from about 150 F. to 198 F. The viscosity of the microcrystalline wax should be above about 65 SUS at 210 F. The oil content of the wax should be less than about and is preferably less than about 2%. The microcrystalline waxes are generally prepared by dewaxing n petroleum residuum fraction. Advantageously this is and have been employed for many uses; At

bemachined to achieve a smooth 2,875,082 Patented Feb.

accomplished by dissolving a petroleum residuum fraction in a dewaxing solvent such as methyl ethyl ketone, and chilling the resulting solution to a relatively low temperature, say from about 5 F. to -20 F., to precipitate a major portion of the wax therefrom. The resulting microcrystalline wax can advantageously be subjected to additional deoiling steps such as by further dissolution in a solvent and crystallization at a relatively low "temperature, or by repulping the wax in a solvent and separating the wax from solvent;

The entire portion of the microcrystalline wax so prepared can be employed to prepare the composition of the IHVE IItl OH, or any fraction separated therefrom such as by fractional crystallization, and blends of such fractions,can be used. It is especially advantageous to use blends of microcrystalline wax having different physicalproperties, such as different melting points, in order to obtain specifically desired properties of the final wax product, in addition to the ability of the final wax cornposition of the invention to. form smooth surfaces.

Pour depressants are well known,

I thereof can be used in the compositions of the present pour depressant in a microcrystalline compositions of the in- 1 olds forthe precision cast- I invention. Pour depressants especially suitable for preparing thecomposition's of the present invention are prepared by condensing a derivative of paratlin wax with an aromatic compound. For example, paraifin wax can be chlorinated and the chlorinated wax condensed with an aromatic compound such as naphthalene, toluene, benzene, phenol, phthalic anhydride, or the like, using the Friedel-Crafts reaction. Aluminum chloride is an especially good catalyst to employ but other catalysts known to be effective in such reactions, such as ferric chloride, stannic chloride, and the like, can be used. Also, if desired, a solvent such as a hydrocarbon naphtha; ethylene dichloride or the like can be used. The poor depressants can also be prepared by dechlorinating chlorinated wax and condensing the resulting unsaturated material with the same aromatic hydrocarbons, i. e., with naphthalene, toluene, benzene, phenol or phthalic anhy tibn are advantageously prepared by incorporating from" about 0.05 to 1.5%

by weight of the pour depressant therein. Incorporation is conveniently accomplished by blending the pour depressant into the wax while the wax is in the molten state.

Toillustrate the preparation of the compositions of the invention, a microcrystalline wax was prepared from a petroleum residuum fraction boiling above about 590 F. at 25 mm. of mercury pressure which had been deasphaltized and selective solvent extracted. The fraction was dissolved in a dewaxing solvent consisting of about equal volumes of methyl ethyl ketone and benzene, with a small amount of toluene, and the resulting solution chilled to about ---16 F. Wax precipitated at this temperature was separated from the solution. The resulting wax was dissolvedat an elevated temperature in a dewaxing solvent consisting essentially of about equal parts of methyl ethyl ketone and benzene. The resulting solution was cooled to about F. and the wax precipitated at this temperature was separated by filtration. This and a wide range 'Wax A warn Properties:

' Melting point F. (AS'lM Dl27-49) 193 170 Viscosity at 210F. BUS (ASTM D446-3 85 83 Penetration at 77 F. (ASIM D55 2) 7 .6. 20

A blend containing equal parts by weight ofWax A and Wax B was prepared. To a portion of this blend, while molten, was added 0.5% by weight of a pour depressant prepared by condensing chlorinated parafiin wax with naphthalene by the Friedel-Crafts reaction using aluminum chloride as the catalyst. The propertiesv As will be observed from the above table, the addition of the pour depressant does not significantly alter the properties of the wax blend; However, the surface characteristics are completely different. In order to'observe the surface characteristics of the wax compositions, each composition was cast in a metal mold and the surface solidifying in contact with air observed. Thissurface should be smooth, since it is often used to reproduce a side ,of a desired metal article, and hence it is contacted with the material usedto prepare the mold for subsequent preparation of the article. The blend containing the depressant had a smooth surface and was an excellent material for the preparation of molds for use in precision metal casting; metal articles so-prepared present a smooth surface and hence generally do not require additional operations such as machining or grinding. The surface of the blend without the depressant was wrinkled, i. e., the surface was rugose, with serpentine lines forming irregular depressions in the wax, so that the wax com-. position was not suitable for the preparation of molds for use in precision metal casting, since metal articles so prepared require additional operations, such as grinding or machining, to achieve a smoothlsurface,

The wax compositions of the invention can be used for purposes other thanthe preparation of molds for metal casting, such as in uses where a smooth surface or coating of a microcrystalline wax is desired. For example, the wax compositions are advantageously used for coating cheese and meat products, for the preparation of wax figures and-wax toys, and as dentalwaxes.

except that the composition, on solidifying from molten state, forms a smooth, wrinklefree surface. H

Other materials can be' incorporated in the waxzto obtain desired properties. For example, paraffin wa'x,

synthetic waxes, a natural wax such as beeswax or carnauba wax, polymers such as polyethylene or polyisobutylene, and the like can be addedto the microcrystalline wax-pour depressant blends of the'invention with good results. However, such materials are preferably added in minor quantities, say from 0.5% to 20%. by weight, and in no event should the such added matter exceed about 40% by weight. p

' Theinvention claimed is: 7

1. A new composition of matter consisting essentially of a microcrystalline wax having an oil content of less than 5% and from 0.05% to 1.5% by weight ofa pour depressant prepared by condensing chlorinated: paraffin wax with a material selected from the group consisting of naphthalene, toluene, benzene, phenol, phthalic anhydride, aniline, xylene, ethyl benzene, cresol, and methyl naphthalene.

2. A new composition of matter consisting essentially of a microcrystalline wax having a melting point of above 135 F., a viscosity of at least 65 SUS at'2l0" R, an oil content of not greater than about 2% by weight and from 0.05% to 1.5% by weight of the condensation product of a derivative of paraffin wax anda material selected from the group consisting of naphthalene, toluene, benzene, phenol, phthalic anhydride, aniline, xylene, ethyl benzene, cresol, and methyl naphthalene.

3. Composition according to claim lwherein the selected aromatic compound is naphthalene.

4. Composition according to claim-f5 1 wherein the selected aromatic compound is toluene. v 5. Composition according to claim 1 wherein the selected aromatic compound is phthalic 'anhydride. p 6. Composition according to claim 1 wherein the selected aromatic compound is benzene. Y

- 7. Composition according to claim 1 wherein the, selected aromatic compound is aniline- References Cited in the file of this patent UNITED STATES PATENTS 2,045,913 I-Ioy et al. June-30; 1936 2,281,941 Lieber May 5, 1942 2,692,835

Capell 0ct. 26, 1954

Claims (1)

1. A NEW COMPOSITION OF MATTER CONSISTING ESSENTIALLY OF A MIRROCRYSTALLINE WAX HAVING AN OIL CONTENT OF LESS THAN 5% AND FROM 0.05% TO 15% BY WEIGHT OF A POUR DEPRESSANT PREPARED BY CONDENSING CHLORINATED PARAFFIN WAX WITH A MATERIAL SELECTED FROM THE GROUP CONSISTING OF NAPHTHALENE, TOLUENE, BENZENE, PHENOL, PHTHALIC ANHYDRIDE, ANILINE, XYLENE, ETHYL BENZENE, CRESOL, AND METHYL NAPHTHALENE.