Anionic Bituminous Emulsions

1. Field of the Invention

This invention relates to improvements in oil-in-water anionic bituminous emulsions. More particularly, this invention relates to the production of oil-in-water anionic bituminous emulsions with the aid of a particular anionic emulsifying agent comprising an alkali lignin and an ethylene oxide adduct of an alkyl phenol.

2. The Prior Art

Aggregates for road building are generally coated with suitable asphalt mixes which include bitumens which affect the coating of the aggregates. The aggregates used are, of course, sand, gravel and other suitable and well known aggregates.

To prevent the emulsion from leaving the aggregate, known as "stripping", the asphalt mixes are provided with additives which are usually of either cationic or anionic surfactants. Formulators are continuously attempting to use more effective surfactants of both the cationic and anionic varieties. Although satisfactory results can be obtained with certain types of both surfactants, certain deficiencies, both as to performance and price, leave room for considerable advancement in this field.

The use of lignin-type materials, specifically lignin amines for use in anionic bituminous emulsions, are disclosed in U.S. Pat. No. 3,123,569 to M. J. Borgfeldt. Further, it is also known to use ethers formed from ethylene oxide and nonyl phenol as surfactants in bituminous emulsions as disclosed in U.S. Pat. No. 3,366,500 to Kracauer. However, no one has shown the advantages obtained by the use of an ethylene oxide adduct of nonyl phenol together with the particular lignin materials of this invention in anionic bituminous emulsions.

Accordingly, it is a general object of the present invention to provide an anionic emulsion for coating aggregates for road building and the like.

Another object of the present invention is to provide an anionic bituminous emulsion for coating aggregates for road building and the like which has universal action, that is, it can be used for all different types of asphalt mixes for the coating of all different types of aggregate.

Other objects, features and advantages of the present invention will be apparent from the foregoing detailed description of the invention.

It has been found that oil-in-water anionic bituminous emulsions capable of producing satisfactory, mechanically stable mixes with aggregates may be effectively prepared by employing from about 30% to about 75% by weight of the emulsion of bitumen as the disperse phase, from about 0.1% to about 10.0% by weight of an anionic emulsifier comprising an alkali lignin and an ethylene oxide adduct of alkyl phenol in a weight ratio of 10:1 to 1:10 of lignin to alkyl phenol adduct, from 0% to 10% sodium borate, with the remainder being water as the continuous phase.

The anionic emulsifier used in the continuous phase of the oil-in-water emulsions of this invention comprises, a mixture of alkali lignin and ether formed from ethylene oxide and alkyl phenol in a weight ratio of from 10:1 to 1:10 of lignin to alkyl phenol adduct.

The lignins employed in the anionic emulsifier used in this invention include alkali lignins from the sulfate (kraft) pulping process, and lignins derived from other alkaline pulping processes, such as soda or modified soda processes. Alkali lignins that have been modified by oxygenation or oxidation may also be used. The lignins may be modified by bubbling oxygen or air through a solution of alkali lignin at pH 10 to 13 and a temperature of 50.degree.C. to 100.degree.C.

The other necessary portion of the anionic emulsifier is the adduct formed from the reaction of ethylene oxide and an alkyl phenol. Alkyl phenols are contemplated to include nonyl phenol, octyl phenol and dodecyl phenol, with nonyl phenol being preferred. The adduct may contain from 10 to 100 moles of ethylene oxide per mole of nonyl phenol, but preferably contains from 30 to 50 moles of ethylene oxide per mole of nonyl phenol.

As stated, the lignin and alkyl phenol adduct are in a weight ratio of 10:1 to 1:10 of lignin to alkyl phenol adduct, preferably the ratio is between 7:3 and 4:6 by weight lignin to alkyl phenol adduct.

In preparing the bituminous emulsions of this invention, an aqueous anionic emulsifying solution prepared as described hereinbelow is intimately contacted with a suitable bitumen by a mixing device, such as a colloid mill, which is capable of producing a vigorous shearing action. The bitumen content of the emulsion can range from about 30% to about 75% by weight of the emulsion depending upon the intended use, preferably about 55% to about 65% by weight. The anionic emulsifier is present in the final emulsion in a concentration ranging from about 0.1% to about 10.0% by weight of the emulsion, preferably about .5% to about 3.0% by weight of the emulsion. Additionally, it may be desirable to add up to 10% by weight of the emulsion, preferably about 1.0% to 5.0%, of sodium borate (borax). It is also desirable to adjust the pH of the emulsion to between 10 and 12, preferably 10.5 to 11.5. Further, it also may be desirable when preparing the anionic emulsifier as a liquid, which may contain, for example, a 40% solids concentration, to add up to about 20% by weight of a lower alkyl alcohol having less than 6 carbon atoms, for example, isopropanol, ethanol, etc., which assists in forming a stable emulsifier.

The "bitumen" used in the emulsion may be derived from Venezuela, Mid-Continent, Western and other bitumen sources and also includes, in addition to bitumen, natural asphalt, petroleum oil, still residues of paving grade, plastic residues from coal tar distillation, petroleum pitch, petroleum resins, solutions of such substances like cut-back asphalt, and the like. Practically any asphalt penetration values ranging from about 40 to about 300 may be emulsified with the aid of the anionic emulsifiers of this invention.

The practice of this invention may be seen in the foregoing examples wherein the anionic emulsifier was used to illustrate its advantages in an oil-in-water anionic bituminous emulsion. In each these examples, the tests were performed according to ASTM D-244.

This example shows a series of emulsions using an alkali lignin, Indulin C, a product of Westvaco Corporation, as the lignin component in the emulsion and various nonyl phenol adducts. As will be seen in the table, a number of emulsions were prepared using varying weight ratios of the lignin to the ethylene oxide adduct of nonyl phenol, see Emulsion 1 and Emulsion 7 through 10 wherein the weight ratio of lignin to ethylene oxide adduct of nonyl phenol was varied between 50/50 and 80/20. Emulsions 1 through 3 show emulsions prepared with ethylene oxide adduct of nonyl phenol having various mole additions of ethylene oxide varying from 9.5 to 50 moles of adduct. Additionally, the emulsions were prepared at additive levels of .1% up to 1.25% by weight of the total emulsifier which was added to an asphalt, in Emulsions 1 through 3, Humble Asphalt (120/150 penetration value) and in the remaining emulsions of Venezuelian Asphalt (120/150 penetration value). Emulsion 6 was run showing the addition of borax at a 5% level. The results of these emulsions are shown in the table below.

The results shown in the table show that satisfactory anionic asphalt emulsions can be made with the anionic emulsifier of the subject invention.

This example illustrates emulsions made varying the weight of nonyl phenol adduct to lignin and showing in some cases the effect of the addition of borax on pumping time. It is also shown by this example and in the results in the table the effect of using an oxylignin in place of the alkali lignin, Indulin C.

The emulsions were made with 120/150 penetration Venezuelian asphalt using an emulsifier dosage of 1.0% at pH 11.0 and an asphalt level of 62%. The pumping time results were:

The results clearly show the effect of the addition of sodium borate to the emulsion ratio and its increase on pulping time. Also, the effectiveness of the oxylignin is shown in the results in the table as illustrated by the lengthy pulping times obtained.

While the invention has been described and illustrated herein by references to various specific materials, procedures, and examples, it is understood that the invention is not restricted to the particular materials, combinations of materials, and procedures selected for that purpose.