US1757083A - Asphalt emulsion - Google Patents

Description

Patented May 6, 1930 UNITED STATES PATENT FFICE ARTHUR L. HALVORSEN, OF NEW YORK, N. Y., AND PIERCE M. TRAVIS, OF RIDGE- WOOD, NEW JERSEY, ASSIGNORS TO THE EMULSION PROCESS CORPORATION, OF JERSEY CITY, NEW JERSEY, A CORPORATION OF DELAWARE ASPHALT EMULSION No Drawing. Original application filed March 3, 1928, Serial No. 258,992; Divided and this application filed December 29, 1928. Serial No. 829,309.

This invention relates to asphalt emulsions and has for its objects the provision of certain improvements in the manufacture of asphalt emulsions and the provision as a new article of manufacture of an improved asfor the most part mixtures of asphalt andphalt emulsion.

This application is a division of our Patent No. 1,714,982. The asphalt emulsions of commerce are water with various agents designed to effect and maintain an emulsification of the asphalt and water. Colloidal clays have been largely used commercially as so-called emulsi- 'fying agents, while numerous other subagents. Relatively .large amounts of these agents have been prescribed as necessary in order to produce a reasonably stable asphalt and water emulsion, and/or suspensions in and water.

the case of clays andthe like.

We have discovered that tri-sodium phosphatecrystalline (Na PO 121-1 0), or dehydrated tri-sodium phosphate (Na PO in -relatively small amounts eifects very satisfactory and true emulsification of asphalt We have moreover found that thisemulsifying action is only effective when limited quantities of. tri-sodium phosphate are used. In other words, there appears to be a critical relationship between the amount of tri-so'dium phosphate used and the efiectiveness of the emulsification, whereby satisfactory emulsification can only be obtained when the amount of tri-sodium phosphate employed is between critical predetermined limits, which vary with different kinds of as- .phalts. Thus, when the amount of trisodium phosphate employed as the emulsifying a ent is increased beyond about 0.4% Na Pg. calculated by weight with respect to the emulsion in the case of a certain grade ofBermudez asphalt, the resulting mixture of asphalt and water while possessing certain aspects of an emulsion is a markedly inferior product to that obtainedwhen less than 0.4% orabout 0.24% of Na' PO is employed as the emulsifying agent. While with a California steam distilled asphaltic base oil residual asphalt the 'best emulsion is obtained when usin more than 0.4% but less than 0.6% Na P Our present invention, based on the foregoingdis'coveries, involves the emulsification of asphalt and water by the emulsifying ac-.,

tion of relatively small amounts of tri-sodium phosphate, preferably not exceeding 0.24%

Na PO,, by weight on the weight of the finished emulsion, in some cases. In the practice of the invention we have secured ex-- cellent results with from 0.1 to 0.3% of Na PO calculated by weight'with respect to the weight of the emulsion. In no case should the tri-sodium phosphate exceed about 0.75% Na PO by weight on the emulsion, and the optimum results will usually be obtained when the amount of tri-sodium phosphate is considerably less than 0.6%

I The following examples illustrate the prac tical application of the principles of the invention: J

'100 kilo ams of water are heated approximately to oiling, as for example by the injection of live steam}. One kilogram of crystalline tri-sodium phosphate equal to about 0.4 kg, Na PO is added to this hot'water. 100 kilograms of freely flowing moltenasphalt are then gradually run into the hot water containing the dissolved tri-sodium phosphate. The mixture is vigorously stirred while the molten asphalt is'being added to-the water. The stirrer-used forthis pur-' ose should be of a fairly active type, such or example as a pro Her stirrer, and should be arranged to dlsseminate the asphalt promptly after it contacts with the water; When the asphalt has been thoroughly and uniformly dispersed throughout the water, themixture is run through an. emulsifying-- machine, such, for example, as a colloid mill; The resulting emulsion discharged from the emulsifying machine is relatively hot and while cooling to room temperature should be gently stirred, .with or without artificial 0001-" ing.

As another example of the application of the invention, we will describe the manufacture of an emulsion containing three parts of asphalt and one part of water. The water (250 kilograms) containing four (4) kiloup by the water as fast as it is fed. These conditions should be guarded against since it is preferable to get the asphalt completely emulsified at the time it enters the water. The preliminary coarse emulsion formed in this way is now fed, continuously and with appropriate stirring, into a mechanical emulsifier, such as a colloid mill, from which the finished fine emulsion is continuously discharged. The emulsion discharged from the emulsifier is cooled, artificially if desired, with gentle stirring and canned, or otherwise prepared for storage or use. Theoperations of cooling and canning are preferably conducted in a continuous manner to prevent asphalt skin formation caused by undue exposure of the Warm and rich emulsion to air.

The cold emulsion resulting from the foregoing operation is of a dark brown'color and of a heavy consistency but will yet flow which is remarkable considering the'high asphalt content (3 asphalt to 1 water) and the small amount of emulsifying agent (1.6 parts Na PQ to 750 parts asphalt or 1000 parts emulsion). The emulsion, while very stable in the cans, reforms true asphalt in a very few minutes when coated on a concrete wall,

cardboard, metal, etc.; the coating being just as water-proof, black and shining as when formed from non-emulsified asphalt. The concentrated emulsion may, if desired, be thinned with water to form a more dilute emulsion. For example, two parts of the emulsion may be mixed with one part of water to make a thin 'brown emulsion of milk-like consistency containing about 50% pure asphalt.

As a third example of the application of the invention, we will describe the manu-v facture of an emulsion containing asphalt and made from a California steam discharged from the emulsifier is cooled very.

quickly by artificial means and canned or otherwise prepared for storage or use. It has also been found that even smaller amounts of tri-sodium phosphate may "the advantageously employed.

While the invention is of general application and can be advantageously practiced with substantially all asphaltic materials, it

is particularly applicable in preparing emul- I sions of asphalts containing relatively small percentages of mineral matter. Thus, for

example, natural or residual Bermudez asphalts. California or similar asphaltic base oil residue asphalts, or cut-back asphalt cements thereof, containing around 1 to 7% of mineral matter are admirably suited for the practice of the invention. Similarly, the residual as'phalts from the distillation of other asphaltic base oil, or cut-back asphalt cements thereof, are vell suited for the practice of the invent-ion. Emulsions made of such asphalts contain relatively small amounts of mineral or similar inert matter, and consequently contain maximum percentages of the desirable hydrocarbon compounds of asphaltic materials. Moreover, in consequence of the small amount of trisodium phosphate used, the emulsions are not contaminated with any substantial quantity of emulsifying agents.

The melting point of the asphalt used in practicing the invention should not be sub 'stantially higher than the boiling temperature of water, since otherwise objectionable steaming, of the water will take place upon mixing the water and molten asphalt. Since the melting point of asphalt is to some extent dependent upon its hardness, as determined by its penetration factor, it follows that in general it is desirable to use asphalts of relatively high penetration factors.

Where the penetration factor is too low, the asphalt may be cut-back With hydrocarbon oils, thereby producing what is known as asphalt cement, to appropriately increase its penetration factor. We have secured excellent results in the practice of the invention using Bermudez asphalt products having a penetration factor of 30 and upwards at 25 0., as determined by the Dow enetrometer and with the aforementioned alifornia state of subdivision. Under a high poweredmicroscope, the emulsions of the invention are seen to consist of minute globules of asphalt very uniformly distributed throughout the water, which constitutes the continuous or external phase of the emulsion.

The emulsions of the invention are moreover characterized by their brown color, thereby further evidencing the very fine state of subdivision of the black dispersed phase (asphalt). The ,color of an asphalt-water emulsion becomes lighter (i. e.. varying from black to brown) as the asphalt becomes more finely subdivided and dispersed in the water. This is believed to be due to the increased reflection and scattering of light in consequence of the increased subdivision and dispersion of the asphalt particles. This color phenomenon is utilized in the preparation of the emulsions, and the operator judges the completeness of the dissemination of the asphalt throughout the, water and hence the desired end-point in the mixing and/or emulsifying operations by the brown color of the resulting product.

The emulsions of the invention are furthermore characterized by their relatively rapid drying qualities, that is, their ability, upon application in the form of a thin coating, to set or reform within a few minutes into an impermeable coalescent coating of true pure asphalt, typified by its shining black appearance. When applied to a surface with a spray gun, the asphalt dries and sets almost immediately, and when applied by a brush or the like, dries and sets in a very few minutes. The drying andsetting of the asphalt is more rapid, the more porous the material to which the emulsion is applied. This rapid drying quality of the emulsion of the invention is due, we believe, to the high degree of subdivision and dissemination of the asphalt whereby greatly increased surface areas are exposed for evaporation of the water.

The emulsions of the invention, when applied and dried, produce an asphalt coating of characteristic black and glossy appearance.

This is'largely due to the fact that the coating consists of pure asphalt uncontaminated with any substantial amounts of emulsifying agents or other inert substances. This is in striking contrast with the so-called asphalt emulsions containing clay and the like, which simply stirring.

. content, can

when dry have a dull, flat appearance. This absence of any substantial amount of emulsifying agents or other inert substances in the asphalt coating produced by the emulsions of the invention, results in securing the maximum effectiveness of the asphalt as a waterproofing or protective medium. It is to be understood, however, that non-emulsion breaking fillers may be added where very thick coatings are desired and suitable fillers giving an initially water permeablecharacteristic may be used so that the water phase may evaporate or fiow off, for if a heavy coating of the pure emulsion be attempted, the outer surface or skin thereof under certain conditions as applied to certain materials would not allow the water to evaporate after such a skin had been formed.

The emulsions of the invention arevery stable and have no tendency to break down on standing. When stored in cans or other receptacles, some slight settling may take place. but the relatively thin layer of supernatant liquor is readily mixed in and the uniformity of the emulsion re-established by The emulsions, more particularly those of relatively high asphalt be readily diluted or thinned with water accompanied by appropriate stirring to produce more fluid or less concentrated emulsions, as desired.

W'e do not desire to be restricted to any theory of the effectiveness of small amounts of tri-sodium phosphate in emulsifying water and asphalts, and the fact remains that small amounts of tri-sodium phosphate produce remarkably effective emulsification of asphalt and water. \Ve believe that the effective emulsifying action of small amounts of tri-sodium phosphate, characteristic of the presentinvention, is due in part to the chemical, and perhaps physical, composition and behavior of tri-sodium phosphate, as well as to its 'presencein amounts preferably not exceeding around 0.6% (Na- 1 0,) by weight on the emulsion, and in no case exceeding about 0.75%.

It should be noted that in accordance with our invention. the complete emulsification may be effected with a fraction of one per cent (1 of tri-sodium phosphate. Qther agents or substances may, however, be added to the emulsion for imparting thereto qualities or properties quite apart from that of emulsification. In this connection, however, care must be taken not to add substances that exercise a deleterious effect upon or, break down the emulsion. In all cases,"however, the additive emulsifying agent will not'substantially exceed 1.5% and the emulsion will- Water and asphaltic constituents soluble in carbon bisulfide.

While we have particularly mentioned trisodium phosphate, other Water-soluble alkaline phosphates of monovalent metals, such as potassium phosphate and/or ammonium phosphate or mixtures of the same may be employed as the emulsifying agent, and are to be understood as included in the scope of the appended claims. The relative cheapness and commercial availability of tri-sodium phosphate, however, make it a convenient agent in practice. Also the separate addition of the necessary component metal salts and a phosphoric reagent may under certain-conditions be employed.

We claim:

1. An asphalt-Water emulsion containing tri-sodium phosphate as an emulsifying agent in amount not exceeding 0.75% Na PO by weight on the emulsion.

2. An asphalt-water emulsion containing tri-sodium phosphateas an emulsif ing agent in amount not exceeding 0.3% Na 0.. by weight on the emulsion.

3. An asphalt-Water emulsion containing about 0.1 to 0.3% by Weight of Na PO as an emulsifying agent.

4. An asphalt-water emulsion containing tri-sodium phosphate as an emulsifying agent in amount not exceeding 0.3% Na PO by Weight on the emulsion and characterized by substantially uniform dispersion of the asphalt in the form of minute globules and further containing not less than 90% by weight of combined water and asphalt constituents soluble in carbon bisulfide and not less than 'one part by Weight of asphalt for each part by Weight of Water.

5. An asphalt-Water emulsion containing tri-sodium phosphate as an emulsifying 9. An asphalt-Water emulsion in the pro duction of which tri-sodium phosphate has been added as an emulsifying agent in amount not exceeding 0.75% Na PO by weight on the emulsion and characterized by substantially uniform dispersion of the asphalt in the form of minute globules.

In testimony whereof We affix our signatures.

' ARTHUR L. HALVORSEN.

PIERCE M. TRAVIS.

agent in amount not exceeding 0.3% Na PO by Weight on the emulsion and characterized by substantially uniform dispersion of the asphalt in the form of minute globules and further containing not less than 90% by weight of combined water and asphalt constituents soluble in carbon bisulfide and at least two parts by Weight of asphalt for each part by weight of Water.

6. An asphalt-water emulsion containing as an emulsifying agent a tri-basic phosphate exceeding the equivalent of 0.75% by Weighton the emulsion. v

8. An asphalt-water emulsion in the production of which tri-sodium phosphate has been added as an emulsifying agent in amount not exceeding 0.75% Na PO by weight on the emulsion.