US2004345A - Core oil compound - Google Patents

Description

Patented June 11, 1935 UNITED STATES PATENT OFFICE 2,004,345 ooaE on. COMPOUND California No Drawing. Original application November '1,

1930, Serial No. 494,187. Divided and this appllcation July 5, 1934, Serial No. 733,880

5 Claims. (01. 22-188) This invention relates to the making of sand cores in foundry work and has to do with a special oil compound for binding the sand particles together in baking the cores preparatory to placing in molds for casting.

The objects of the invention are to provide a binder oil compound for the above purpose which will overcome the objections to other oils and compounds heretofore used in this work, and which will yield a firm core with less baking, also a more friable core after casting, one which is highly compressible to avoid cracking of castings in shrinking, also such an oil composition which will evolve but a relatively small amount of gas as compared to linseed and other oils previously used in sand core binders.

The present case is a division of our pendin joint application filed under Serial No. 494,187 on November 7, 1930, to cover certain phases of the invention disclosed but not claimed therein as will hereinafter appear.

Before describing our special core oil compound it would be well to state that many substances having more or less of an adhesive nature have heretofore been used for core sand binding purposes, including wheat flour, cereal products, dextrine, gums, resins, pitch, molasses, etc., in great array, as well as many oils, particularly the various drying oils, some of the semi-drying oils, and non-drying oils such as mineral oils, but the general practice (apart from the extensive use of wheat flour mixed with the moist sand) gradually centered around linseed oil and mixtures containing it, and insofar as oil binders are concerned this became of general use, perhaps due principally to its quick drying properties, its tenacious film to hold the sand particles together, and its low price for the common grades used for the purpose. Linseed oil and other oilsused pure in the sand, also in various proportions mixed with other oils, also with soap, water and other substances, however, gave rise to numerous objections when used as 'a sand binder in core work due to the fact that after forming the cores they are heated in an oven and baked at a considerable temperature to dry out or harden the oil and lock it to the sand particles, and since a common property of oils and greases generally is tofirst'soften and become more fluid when heat is first applied before drying out, it follows that the oily content of the sand, if appreciable in amount, first became more fluid upon application of the baking;

heat and settled toward the lower part of the care so that it no longer was evenly distributed throughout the mass of sand which it was to bind together, and with a result that there was too little in the upper. part of the cores and too much at the bottom, the baking was uneven, the cores swelled, sagged, were uneven in hardness, frail above, and sometimes quite impervious'over the oil-settled areas so that the gases formed in casting could. not escape and much gas became imprisoned in the molten metal to greatly injure the casting. Also, when the molten metal such as iron or steel was poured against such uneven cores it would burn to the core in some places creating rough areas requiring clipping and grinding and sometimes resulting in loss of the casting. Also, over-hard cores did not permit of normal shrinking of the castings in cooling, particularly in aluminum casting where the shrinkage is verygreat and the metal frequently thin so that in consequence the castings often split on account of the resistance ofiered by the hard sand cores within.

A further objection to linseed oil, especially when used alone, was the great quantities of gas evolved from the heat of the metal when cast, and a feature in common with oils generally is that being greasy they are repellent to the water necessarily mixed with the sand in forming the mold or core and hence render it dimcult to secure even distribution throughout the sand.

In experimenting to overcome the above and other objections to linseed oil and its mixtures as a core binder, we have discovered after practical trials of many different oils and oil compounds that among the drying oils there is one oil which so far as is known was never used practically in sand core work before our invention but which possesses properties which may form the basis of a sand core binder of outstanding merits. This, oil is China-wood oil, and intensive investigations in foundries all over the country, as well as the literature of the art, have revealed no knowledge of its use in such work, and but one casual mention of it (in Hoskins Patent No. 1,392,013 of Sept. 27, 1921), but which does not show it in any useful combination.

One reason for the neglect of or lack of interest shown in lthis specific oil was due no doubt to its being considered but one of the many drying oils though generally of much higher cost than the cheap grade of linseed oil generally used for core work, and the fact that when used alone or simply mixed with other oils and incorporated into the sand, it shows no advantages over linseed oil, but in fact shows a disadvantage inasmuch as it is more repellent to water, making it more difficult to mix evenly in the. moist sand,

sion in the sand and and in common with all other oils it first becomes thinner or more fluid upon being heated, but seems to do so to even a somewhat greater degree so that if the oil impregnated sand core is baked in an oven to harden it, the oil in first becoming more fluid, migrates to the lower strata of sand so that the cores have all the faults enumerated in this respect to linseed oil.

This oil, in common with general class of oils known as drying oils may be emulsified with water with the aid of any of the numerous emul-, sifying agents used with drying oils as generally known to industrial chemists, such agents being the various alkalies, such as ammonia, caustic and carbonates of potash, soda, oleate and stearate soaps, variT1's glutinous materials such as gLuns, resins, dextrines, eggs, casein, fish glue, starch, etc., and we have found that emulsions of this oil may be made which are perfectly miscible with water in all proportions used in sand core making so that perfect dissemination of the oil in the sand is easily effected, and also that with some emulsifying compounds the oil when thus widely the presence of water, appears to harden first without first becoming more fluid when heat is applied in baking the core so that all migration of the oil is overcome, and besides this, the oil hardens at temperatures from about 250 F. to

300 F. as against 540 F. for the same oil. used plain, or against about 400 F., or more, for linseed oil sand cores. Also that the time of baking is but about one-half or two-thirds that required for linseed oil cores.

We have also found that China-wood oil alone, however, even in emulsion form, is of little value in core work as it lacks tenacity and strength and we have found that it requires the addition of other binding materials to make it useful, such materials including various modifying oils such as perilla oil, non-volatile mineraloil, etc., to modify its character and render it useful, or cereal binders may be added and will be found to mix readily when desired to' produce unusually hard cores,

Inthe baking process, our oil binder in its preferred form solidifies at once in the sand upon the application of the baking heat and does not become thinner or soften and migrate to cause the cores to sag and lose shape and true dimensions, yet, after casting, the sand may readily be poured from the cast article upon slight shaking or tapping.

Of the various emulsifying agents which we find to show the quick hardening eifect with Chinawood oil when in water-miscible aqueous emulheated, are: triethanolamine, diethanolamine, monoethanolamine and caustic soda. The triethanolamine of commerce contains also some of the di. and mono. variety.

Our preferred formula is:

Water 40 fluid ounces Triethanolamine 8 fluid ounces China-wood oil 50 fluid ounces Perilla oil 1 10 fluid ounces Mineral oil 10 fluid ounces (sp. gr. of about 0.9272) 21 B., the grade known as dark neutral oil gives good results;

The perilla oil increases the toughness and binding properties of the compound, and the mineral oil contributes to a certain flexibility, also has some sand binding properties in the combination. Any other oils having similar properties will do in place of these if desired.

disseminated in the sand in binding materials water-miscible aqueous emulsion form, and in The materials are mixed in the order given and triturated for a short while until the chemical action between the triethanolamine and the vegetable oils is completed and at whichtime an emulsion of the ingredients is effected which is perfectly miscible with water, and the emulsion is substantially permanent, especially if run through a good mixer or colloid mill, samples kept portions of the various ingredients may be'altered somewhat as exact quantities are not important, also the mineral oil may be somewhat lighter or heavier. To reduce cost, the triethanolamine may be cut down to the minimum at which it will form a stable or permanent emulsion of rich milk-like consistency.

Our special water-miscible emulsion is used in the sand of usual moisture content suitable for molding, in proportions of from about 1 part of the emulsion to about 10 to 80 parts of sand, depending on the nature of the sand as well as the weight of the core to be supported, and under all conditions will yield an even porous core, true to form, giving off little gas, and extremely friable after being subject to the heat of the molten metal so that it pours freely from the casting. Water in any quantity may be added to the emulsion either before or after adding it to the sand and will be found to mix readily.

In considering our invention it should be noted that it consists of a substantially permanent water-miscible aqueous emulsion of China-wood oil as the principal sand binding ingredient together with a lesser quantity of other binding materials to modify the nature of the wood oil and adapt it to core binding purposes, and while the four special emulsifying agents named which so noticeably accelerate the hardening of the oil at low temperatures upon the application of heat to the core are of especial importance, the gen eral formula or its equivalent with other modifying binding materials instead of the specific oils mentioned, all made up with any of the wellknown emulsifiers in a manner to form a permanent aqueous emulsion which is water-miscible, is novel, and has value in the art as it overcomes the excessive gas and other disadvantages of linseed oil as heretofore used, and gives a core of extreme friability after casting.

Therefore, while the copending case has claims limited to the amine group of emulsifying agents and/or the specific modifying oils, and the present divisional case is predicated upon the species relating to the use of caustic soda as one of the special emulsifying agents which causes the oil in the application of heat in baking the cores, with-- out first softening, the case also contains claims to China-wood oil in combination with other sand all in substantially permanent which the China-wood oil is the major sand binding constituent," as this is a phase of the invention not claimed in the copending case and which applicants are the first to produce to gain the advantages of this oil.

We therefore claim:

1. A sand core binder comprising water, Chinatially permanent water-miscible aqueous emulsion of oils in which China-wood oil is the mador A sand binding constituent.

5. A sand core binder comprising a substantially permanent water-miscible aqueous emulsion of sand binding materials in which Chinawood oil is the major sand binding constituent.

CARRIE ANNA QUANDT.

Executrix ofthe Last Will and Testament of 10 Herbert L. Quandt, Deceased.

JULIUS J. HORAK.