US2699997A - Core oil containing a drying oil and asphaltenes - Google Patents

Description

United States Patent CORE OIL CONTAINING A DRYING OIL AND ASPHALTENES Harley F. Hardman, Lyndhurst, and Everett C. Hughes, Shaker Heights, Ohio, assignors to The Standard Oil Company, Cleveland, Ohio, a corporation of Ohio N0 Drawing. Application July 31, 1951, Serial No. 239,642

12 Claims. (Cl. 106- 38.7)

This invention relates to core oils or liquid core binders, and more particularly to core oils comprislng a drylng oil and asphaltene, and cores made with the same.

In foundry practice, the internal surfaces of most castings are formed with the aid of sand cores. are prepared from mixtures of sand and a suitable bmder. The binders employed are generally organic substances and must have certain properties in order to be commercially practical. They must, in the first place, be inexpensive, since the cores are used in large quantities and the binder is destroyed after use. They must wet sand readily and when mixed with the sand should not adhere to the core box or mold. They must display adhesive properties when first mixed with the sand and shaped to form a green core, and this green core must be capable of being baked to a finished core of high tensile and dry compression strength. Since the cores are frequently prepared several weeks in advance of their ultimate use, the binder must also be non-hygroscopic and must retain its binding properties for a protracted period. Finally, the binder must be capable of being burned ofi in order to recover the sand from used cores.

Heretofore drying oils such as linseed oil have been employed. These give cores of high strengt but unfortunately drying oils are rather expensive. Therefore, mixtures of linseed oil with other substances capable of serving as an extender for the linseed oil have been proposed, such as a mixture of rosin, linseed oil and petroleum oil. Rosin alone as a binder gives a soft core which readily disintegrates, while linseed oil produces a hard core By varying the proportions of the two ingredients, cores having properties intermediate between those of rosin and linseed oil cores can be prepared which meet existing conditions. However, rosin-containing core oils have the disadvantage that the rosin tends to crystallize I or sludge, destroying the homogeneity of the solution and producing a non-uniform core.

In accordance with this invention core oils are prepared comprising a drying oil and an extender consisting essentially of asphaltene in an amount to improve the binding properties of the oil. There is no critical lower limit of extender concentration for operativeness, the amount used being that required to obtain an improved result. However, there is an upper limit of asphaltene content of about 40% beyond which no improvement in breaking strength is realized but rather a poorer result is obtained. Obviously, economy dictates use of as much extender as possible. Thus the highest percentage of extender which will still give favorable cores will usually be used, unless other circumstances dictate other ratios. However, it will generally not be the most economical and practical to prepare and employ a mixed core oil containing less than about 5 to 0f the extender. Thus a desirable range for the asphaltene alone is from 5 to about 40% and the optimum range of asphaltene is from about 7.5 to 30% by weight of the core oil. It is therefore an object of the invention to provide a novel core oil comprising a drying oil and asphaltenes.

As a further feature of the invention, it has been found, as shown in comparable tests below, that if a mixture of asphaltene and another extender comprising petrolene is incorporated in the drying oil, as much as about 60% extender may be employed with improved results, provided the amount of asphaltene does not exceed about 40%. Thus with the maximum amount of extender, the

asphaltene should not exceed about 40% with about 20% 8 These cores 'ice petrolene. This use of a mixed extender represents a highly desirable increase of about 20% over the maximum amount which may be employed if asphaltene alone is used.

Petrolene when included serves as a diluent for the asphaltene. However, the ratio of petrolene to asphaltene should not exceed about 4 to 1 where the maximum amounts of extender is used since amounts of petrolene in excess of this reduce the binding properties of the resulting core oil considerably below those of drying oil alone. The optimum ratio of asphaltene to petrolene is between about 1:1 and about 1:2 with the amount of the mixed extender not exceeding about 60% by weight of the core 'oil composition. Thus another object of the invention is to provide novel core oils comprising a mixture of a drying oil, asphaltenes and petrolenes.

Combinations of a drying oil and asphaltene in certain definite proportions unexpectedly give cores having a higher tensile strength than those produced from core oils composed only of a drying oil or of asphaltenes. This result is contrary to the results obtained when rosin, for example, or like extender, is mixed with a drying oil. A still further object of the invention is, therefore, to provide improved sand cores for metal casting compris ing sand and novel core oil binder compositions.

Asphaltenes and petrolenes are components of asphalt. The term asphalt is used herein to apply to both native asphalts and pyrogenous asphalts. Native asphalts include asphalts occurring naturally in a pure or fairly pure state, also asphalts associated naturally with a'substantial proportion of mineral matter, such as sand, sa'ndstone, clay, etc., which are separated from the asphalt by solvent extraction methods. Pyrogenous asphalts include residues obtained from petroleum by various means, such as distillation (e. g., still bottoms, or residual oil), blowing (e. g., blown asphalts), etc. The term petrolene is used herein to refer to that portion of asphalt which goes into solution when the asphalt is extracted with 50 volumes of normal pentane. The ,termasphaltene is used to refer to that portion of the residue, remaining after pentane extraction, which is soluble in carbon disulfide. Asphaltenes and petrolenes having a relatively large proportion of non-aromatic hydrocarbons are preferred. Satisfactory natural mixtures of asphaltenes and petrolenes may be obtained, for example, from propane precipitated asphalt and asphalt derived from a Mid-Continent crude. Linseed oil is the most commonly employed drying oil in formulating core oils, but other well known drying oils capable of binding sand to produce a core and derived from fish or vegetable oils may be used, such as sardine, menhaden fish, oiticica, tung, walnut, soybean, dehy-' drated castor, perilla, sesame, rapeseed, hempseed, raisin seed, grapeseed, poppyseed, tobacco seed, and mixtures thereof. The term drying oil is used herein to include both drying and semidrying oils.

The core oil may contain a volatile solvent, preferably one with a slow evaporation rate, so that it is lost only slowly during baking of the core. Kerosene, petroleum naphtha, mineral spirits and the like are satisfactory. However, this is not an essential component. Asphaltenes and petrolenes are readily soluble in drymg o1ls, either at room temperature or upon warming to about 150 C. For example, they readily dissolve in linseed oil on warming to C. However, in some instances solubility may be improved by addition of one of the above-mentioned solvents. Also, certain asphalt fractions are highly viscous, and addition of a solvent will reduce-the viscosity of the composition to a workable range.

The core oils are prepared by blending the ingredients, using standard equipment, to form a solution free of suspended or undissolved material. The resulting core oil is then suitable for mixing with sand to produce a core.

The. following examples illustrate particular embodi ments of the invention, but it will be understood that with the above disclosure.

3 EXAMPLE 1 Since dry breaking strength is the property of a core which is entirely dependent on the binder used, th s property of cores. made? with the core. oils produced. in accordance with the invention: and the prior art. 18 used asav standard of comparison of cone oil eifectiveness. The dry breaking strength was measured in the following way." 100 cc. of sand (Lake Erie, 4080 mesh), 4 cc. of water and aistipulated amount, usually from 2 to. 9 grams, of the core oil. were mixed, formed into green beams 1" x 1" x 6" and. baked for 1 /2 hours at from 350 to 450 F. The beams were then cooled, placed on a five inch span and loaded. at the center at the rate of 24 poundsper minute. The transverse strength was taken as the load at the instant the beam broke. All tests were run at room. temperature C.).

Core oils were prepared as listed in. the following table, formed into green beams and. baked. The beams were then tested as set. forth in the test given above, with the following results:

Breaking strengths of test cores Quantity(s) of Core Binder" 7 (e s) Baking Breaking Temp, F.

' Strength,

pounds Composition of Core i'nder Linseed Oil Illinois Asphaltenes.

zene. Coal tar pitch Rosin 50.% 180 M. P. propane asphalt. 50% Atlas Clay polymer 1% Lead naphthenate drier.

50% 1;!0" M.. P. propane as 1 1111 t. I 50% Atlas Clay polymer 450 i 1% Lead naphthenate drier. {50% Asphaltenes. I 50% Linseed Oil {25% Asphaltenes.

75% Linseed Oil 25% 180 M. 1?. propane precipitated' asphalt (50% asphaltenes, 50% petrolenes). 75%Linseed Oil 50% 180 M. P. propane precipitated asphalt (50% asphaltenes, 50% petrolenes). 50% Linseed Oil 75% 180 M. P. propane preeipitated asphalt (50% asphaltenes, 50% pet-rolenes). 25% Linseed Oil 50% 150-160 M. P. oxidized cc. flux asphaltenes of high aromatic content,

60% petrolenes). Linseed Oil 50% 180 M. P. asphalt from a Mid-Continent crude (40% asphaltenes, petrolenes). 50% Linseed Oil 50% 210 pen pipe still bottoms (12%%aspl1a.ltenes,

87 petrolenes) 50% Linseed Oil Standard "penetration test.

A comparison of samples 15 and 18 or 21 shows that whereas 50% of extender composed exclusively of' asphaltenes is excessive, 50% of an extender mixture with a ratio of asphaltene to petrolene of 1:1 is very advantageous. This shows the value of petrolenes in permitting an increase in the total amount of extender tolerable in the composition.

Samples 15 and 16 show mixtures of linseed oil and asphaltene which are satisfactory and also show that even small amounts of asphaltene in a core oil give stronger cores than those prepared withlinseed oil alone and this is true up to substantial proportions of added asphaltene. Thus, these samples show that cores of comparable strength to thoseprepared with a drying oil alone can be obtained by incorporating. with: it something less than 50% asphaltene, which by plotting values and extrapolating, gives as a maximum value of about 40% asphaltene for a core product which has a breaking strength which is as great as that prepared with linseed oil alone. Values of asphaltene above this tend to be less strong and values below 40% are stronger, depending upon the quantity of asphaltene employed. This does not necessarily mean that the strength of the cores are progressively stronger as the amount of asphaltene is increased in an amount between 0 and 40% but only that there will bea noticeable-increase in strength for various percentages of added asphaltene up to about 40% an increase which becomes appreciable at a value of added asphaltene of about 25%.

Sample 17 shows that the same increase in breaking strength is available when as much as /2 of the asphaltene is substituted with petrolene and the asphaltene-petrolene mixture is used in the same percentage in the core oil. Sample 18 also shows that the same breaking strength for the core can be realized even if the amount of extender is increased substantially if an asphaltene-petrolene mixture is used in place of asphaltene alone, i. e., the some breaking strength for the core is realized with twice as much mixed extender as with 25% added asphaltene alone, which shows that the inclusion of petrolene with asphaltene improves materially the binding characteristics of the asphaltene extender. Sample 19 shows, however, that a 1:1 asphaltene-petrolene mixture cannot satisfactorily replace of the drying oil without a loss of binding strength, just as 50% of asphaltene alone is too high for. substitution without loss of breaking strength. Thus the maximum amount of the mixed asphaltenepetrolene extender of equal proportions is between 50 and or about 60% from a plot of the values.

Sample No. 22 shows that a composition containing 6% asphaltenes and 44% petrolenes (a ratio of 1:7) has too high a ratio of petrolenes to asphaltenes, but sample No. 21 demonstrates that a mixture of 20% asphaltenes and 30% petrolenes (a ratio of 2:3) is satisfactory. Samples 16, 17, 18 and 21 demonstrate the optimum proportion of asphaltenes to petrolenes and of both to linseed oil. The limit for the ratio of asphaltene to petrolene in an asphaltene-petrolene extender mixture for 50% substitution for linseed oil can be shown therefore to be about 1:4.

Sample No. 20 shows the effect of a high aromatic hydrocarbon content in the asphalt, and is to be compared with sample No. 21, where the asphalt was highly paraflinic in nature. These tests demonstrate that those asphaltenes of paraflinic nature are preferable as an extender additive to core binders.

EXAMPLE 2 Core oils were prepared comprising 40% linseed oil and. 60% M. P. Cleveland asphalt (40% asphaltenes, 60% petrolenes) and made into test beams as in Example 1. The beams exhibited a breaking strength superior to that of beams made from linseed oil binders.

Although linseed oil is usually employed because of its availability and of economic factors, other drying oils are recognized as useful as core binders and may be successfully employed in the present invention. Linseed oil is not considered to possess any particular component or property which makes it unique for this purpose. Examples of other drying oils which can be used are noted above.

Core oils prepared in accordance with the invention produce a good green bond, and, after baking, display a breaking strength superior to that obtainable by employing a drying oil alone. Since they are less expensive than the commonly-used drying oils, they constitute a useful contribution to the art.

All proportions and percentages in the specification and claims are by weight. The invention has been discussed and described by certain specific examples which will be understood to be illustrative only and not limiting to the inherent scope of the invention and to the modifications which will be apparent to those familiar with the art from the description and claims.

We claim:

1. A core oil consisting essentially of a mixture of a drying oil capable of binding sand to produce a core and an amount of asphaltene in the range from about 5% up to about 40% by weight to improve the binding properties of the drying oil, said core oil being capable of producing a core having a higher tensile strength than a core produced from a drying oil alone.

2. A core oil according to claim 1 in which said drying oil is linseed oil.

3. A core oil consisting essentially of a mixture of a drying oil capable of binding sand to produce a core, an amount of an asphaltene in the range from about 7.5% to about 30% by weight and an amount of a petrolene in the range from about to about 30% by weight to improve the binding qualities of the drying oil, the ratio of petrolene to asphaltene not exceeding 4: 1, said core oil being capable of producing a core having a higher tensile strength than the core produced from a drying oil alone.

4. A core oil according to claim 3 in which said drying oil is linseed oil.

5. A core oil consisting essentially of a mixture of a drying oil, an amount of asphaltene from about 5% to 40% by weight, and an amount of petrolene not exceeding 30% by weight, the ratio of petrolene to asphaltene not exceeding 4:1, said core oil being capable of producing a core having a higher tensile strength than a core produced from a drying oil alone.

6. A core oil according to claim 5 in which the drying oil is linseed oil.

7. A core for metal casting comprising a mixture of sand and a core oil, said core oil consisting essentially of a mixture of drying oil and an amount of asphaltene from about 5% to about 40% by weight, the amount of asphaltone being sufficient to provide a core having a higher tensile strength than a core containing a drying oil alone.

8. A casting core according to claim 7 in which the drying oil is linseed oil.

9. A casting core according to claim 7 in which the asphaltene comprises from 7.5% to 30% by weight of said core oil.

10. A core for metal casting comprising a mixture of sand and a core oil, said core oil consisting essentially of a mixture of a drying oil, an amount of ashpaltene from about 5% to by weight and an amount of petrolene not exceeding 30% by weight, the ratio of petrolene to asphaltene not exceeding 4: 1, said core possessing a higheitensile strength than a core containing a drying oil a one.

11. A casting core according to claim 10 in which the amount of asphaltene is from 7.5 to 30% by weight.

12. A casting core according to claim 10 in which the drying oil is linseed oil.

References Cited in the file of this patent UNITED STATES PATENTS 1,778,329 Mason Oct. 14, 1930 1,970,916 Payne Aug. 21, 1934 2,047,297 Stahl July 14, 1936 2,256,832 King Sept. 23, 1941 2,444,413 Weston July 6, 1948

Claims (1)

1. A CORE OIL CONSISTING ESSSENTIALLY OF A MIXTURE OF A DRYING OIL CAPABLE OF BINDING SAND TO PRODUCE A CORE AND AN AMOUNT OF ASPHALTENE IN THE RANGE FROM ABOUT 5% UP TO ABOUT 40% BY WEIGHT TO IMPROVE THE BINDING PROPERTIES OF THE DRYING OIL, SAID CORE OIL BEING CAPABLE OF PRODUCING A CORE HAVING A HIGHER TENSILE STRENGTH THAN A CORE PRODUCED FROM A DRYING OIL ALONE.