US3220953A

US3220953A - Emulsions prepared with cationic emulsifier

Info

Publication number: US3220953A
Application number: US217236A
Authority: US
Inventors: Merton J Borgfeldt
Original assignee: Individual
Current assignee: Individual
Priority date: 1962-08-02
Filing date: 1962-08-02
Publication date: 1965-11-30
Anticipated expiration: 1982-11-30

Description

PRESSABILITY SECONDS Nov. 30, 1965 M. J. BORGFELDT NH4 c| PERCENT INV ENTOR MERTON J. BORGFELDT United States Patent 3,220,953 EMULSIUNS PREPARED WITH CATIONIC EMULSIFIER Merton J. Borgfeldt, 64 Sunview Drive, San Francisco, Calif. Filed Aug. 2, 1962, Ser. No. 217,236 2 Claims. (Cl. 252-31ll.5)

This application is a continuation-in-part of Serial No. 2,060, filed by the applicant in the US. Patent Office :on January 12, 1960, and now abandoned, which, in turn, is a continuation-in-part of application Serial No. 693,590, by the same applicant, filed in the US. Patent Office on October 31, 1957, later abandoned.

This invention relates to bituminous emulsions of th oil-in-water type. It also relates to emulsions of the oilin-water type in which the disperse phase, instead of being a bituminous material, is some other thermoplastic, organic, water-insoluble, water-emulsifiable material.

Bituminous emulsions of the oil-in-water type are widely used and have been used extensively for many years in paving work and the like. Such emulsions are mixed with mineral aggregate, and when such an emulsion breaks or dries, it deposits the bituminous material on the aggregate to act as a binder. Emulsions of this character are advantageous because, among other things, they are noninflammable, they do not require the application of heat to melt solid bitumen, and they do not require the use of a volatile, inflammable thinner. Bituminous emulsions as used heretofore have, however, certain disadvantages, among which may be mentioned the following:

It is necessary that an emulsion remain emulsified during storage and shipment and be stable against breakdown on pumping and agitation. Yet, when an emulsion is mixed with an aggregate, it is desirable that the emulsion break quickly and deposit the bitumen rapidly on the aggregate particles. It is difiicult to achieve a delicate balance between an emulsion which is stable in storage, shipment, agitation and pumping, but which when mixed with aggregate will break quickly and deposit the bitumen on the aggregate particles. These difliculties are aggravated if the aggregate is moist and/ or if it is of a hydrophilic, siliceous nature. Wet conditions and the requirement that a hydrophilic, siliceous aggregate be used, are circumstances that are frequently encountered in practice.

Emulsifying agents employed heretofore have been predominantly of the anionic type, which is typified by the sodium salt of a fatty acid such as oleic acid. In sodium oleate the oil-solubilizing group is contained in the anion, RCOO. It is the anion of this type of emulsifying agent, which contains the oil-solubilizing group (represented by R) and which becomes afiixed to or associated with the dispersed bitumen particles. For this reason this type of emulsifying agent is known as anionic or as the anion-active type.

More recently it has become known that cationic or cation-active emulsifiers may be used and that they have certain important advantages.

Particularly, it is now known that salts of quaternary nitrogen bases are excellent cationic emulsifying agents. These cationic salt materials have the general formula r Rr-III-Rg X R4 in in which R R R and R are organic radicals, each having a carbon-nitrogen linkage to the nitrogen atom, X is an anion whose valance does not exceed 2, and m and n are small integers which indicate the molar proportions of the cation and anion required to form the respective salt. Preferred emulsifying salts are those in which the organic radicals R R R and R are alkyl, alkenyl, hydroxyalkyl, aryalkyl and alkylaryl radicals of 1 to 24 carbon atoms and heterocyclic groups of 4 to 10 carbon atoms in which from 2 to 3 of the nitrogen valences are shared .by two carbon atoms in a single heterocyclic group. In all of these salts of quaternary nitrogen bases, suitable for use as cationic emulsifiers in the preparation of oil-in-water type emulsions, the aggregate number of carbon atoms in the cationic portion of their molecule should be large enough to impart oil-solubility and emulsifying properties, and preferably should be equal to not less than 20 and not more than 30 carbon atoms. In other words, this class of cationic quaternary nitrogen-containing compounds is formed by salts of tetra-substituted ammonium bases and by salts of heterocyclic nitrogen bases, such as pyridinium, quinolinium, isoquinilinium, morpholinium, piperidinium, imidazolinium, and other like quaternary nitrogen-containing bases. The anion may be'either a halide (X), a methosulfate (SO4CH3 a nitrate (NO or the like ion. Monovalent anions are preferred, particularly the halide anions.

Numerous cationic quaternary nitrogen-containing emulsifiers may be employed for the preparation of cationic oil-in-water type emulsions. Among them, to mention but a few, are:

N,N-dimethyl-N-benzyl-N-octadecyl ammonium chloride N,N-dimethyl-N-hydroxyethyl N dodecyl ammonium chloride N,N-dimethyl-N-benzyl-N-octadecenyl ammonium chloride N,N-dimethyl-N-benzyl-N-dodecyl ammonium chloride N,N-dimethyl-N-hydroxyethyl-N-benzyl ammonium chloride Hexadecyl pyridinium chloride Hexadecyl triethyl ammonium bromide Otcadecylbenzyl trimethyl ammonium methosulfate Isopropylnaphthyl trimethyl ammonium chloride Octadecyl pyrodinium bromide 1-(2-hydroxyethyl)-2-heptadecenyl-l-(4-chlorobutyl) imidazolinium chloride Hexadecyl methyl piperidinium methosulfate Dodecyl hydroxyethyl morpholinium bromide Among the quaternary nitrogen-containing materials available in commerce as cationic emulsifiers for the preparation of oil-in-water type emulsions there are quarternary ammonium salts, such as quaternary ammonium halide materials sold by O ronite Chemical Company of San Francisco, California, under the trademarks ATM- 50 and ADE-50; materials sold by Armour and Company under the several Arquad trademarks; materials sold by National Aluminate Company under the several Nalquat trademarks; certain quaternized materials developed and sold by the Society of Chemical Industry in Basel, Switzerland, under the several Sapamine trademarks, and many others.

The active cationic component of these materials contains the characteristic positively charged quaternary nitrogen configuration in which the aggregate of carbon atoms of R R R and R is sufiioient to impart oil-solubility and emulsifying properties, and preferably is equal to not less than 20 and not more than 30 carbon atoms.

Best emulsification can be achieved with those among the aforesaid quaternary nitrogen-containing materials in which the active cationic component contains at least one long aliphatic hydrocarbon chain of not less than 12 and not more than 24 carbon atoms, such as an alkyl or an alkenyl chain. This latter chain may be derived from a mixture of organic materials such as tallow, soybean oil, lard, etc.

It is a known advantage of the above and other like cat-ionic emulsifiers that they produce oil-in-water bituminous emulsions which deposit the bitumen on aggregate more quickly and more effectively than do emulsions in which the emulsifying agent is of the anion-active type. A convincing demonstration of this phenomenon can be carried out in the following manner:

Two similar quantities of the same lot of siliceous hydrophilic aggregate are taken. Each is wetted with a predetermined amount of water. Then a predetermined amount of an asphalt emulsion is added to each of the wetted samples of aggregate, the emulsions being identical except that in one case the emulsifying agent is of the cationic type and in the other it is of the anionic type. The emulsion and aggregate are mixed together for about three minutes. It will be observed that, during mixing, an anionic bituminous emulsion, i.e., an emulsion made with an anionic emulsifier and characterized by an alkaline pH above 7.0, and preferably above 9.0, will not break down. After the lapse of three minutes of stirring, if a stream of flowing water is used to wash the aggregate, it will be observed that the water washes the anionic emulsion off of the aggregate and that the aggregate is virtually uncoated. This demonstrates that an anionic emulsion of the usual type requires, under the test conditions, a relatively long period of time for deposition of the bitumen.

By way of contrast, it will be observed that during mixing of the wetted aggregate with a cationic bituminous emulsion, i.e., an emulsion characterized by a pH below 7.0, and preferably between 4.0 to less than 7.0, the aggregate becomes coated by reason of breakdown of the emulsion and deposition of the bitumen on the aggregate particles. The deposit of bitumen acts as a binder and increases the viscosity of the mix. At the end of three minutes, the washing test described above is repeated. It will be observed that the aggregate particles are thoroughly and completely coated with the bitumen.

The test conditions just described, which will be refered to as the Stone Coating Test, simulate conditions encountered in practice. For example, in many cases the available aggregate is of a siliceous, hydrophilic character and is very difficult to coat with bitumen from an anionic emulsion. Also, the aggregate is frequently wet, which makes coating even more difficult.

Notwithstanding the advantages above described, cationic emulsifiers and emulsions have certain drawbacks and disadvantages. Thus, cationic emulsifiers are considerably more expensive than anionic emulsifiers. Moreover, the same balance as in the case of anionic emulsions is desired in a cationic bituminous (asphalt) emulsion, i.e., the emulsion should have a uniformly small particle size and should not deposit an excessive amount of large partciles or shot on a screen in ASTM -D 24455 Sieve Test; it should remain stable in storage and when agitated and pumped, but should break down readily and speedily upon admixture with aggregate to coat the aggregate effectively. This balance is difficult to achieve.

The aforementioned cationic quaternary nitrogen-containing salts, although a number of them have been described in the art as valuable addition agents to nonemulsified bitumen, and as emulsifiers therefor, e.g., by Dohse and Spoun in their US. Patent No. 2,191,295, as a matter of fact frequently fail to provide emulsions that remain stable in storage and, particularly, while being handled and pumped, prior to the application of the emulsion to the aggregate, and thus fail to achieve a satisfactory coating of this latter by the bitumen, such as an asphalt.

It is an object of the present invention to provide improvements in cationic bituminous emulsions of the character described.

It is a further object of the invention to provide a means of improving the results of the aforementioned Sieve Test and, particularly, pumping and handling stabilities, in other words, to provide a means of lowering viscosity, without inducing, however, a premature breakdown of the emulsion, and without adversely affecting thereby the formation of a satisfactory coating of bitumen on the aggregate.

These and other objects of the invention will be apparent from the ensuing description and the appended claims.

I have found that the properties of cationic emulsions, that is, of oil-in-water type emulsions of bitumen and the like materials, in which the effective or major emulsifying agent is a salt of a quaternary nitrogen base, can be markedly improved by the introduction of a small amount of any one (or of more than one) of certain additive salts.

These properties include: emulsion quality, that is smooth texture, substantial freedom from graininess, absence of settlement and skin formation; high plating (deposition) ability; stability in storage; mixing stability, that is while mixing the emulsion with the aggregate; pumping stability; lower viscosity suitable for coating and paving work; much higher degree of adhesion of the bituminous binder component to the aggregate surface; higher mat strength of the corresponding emulsionaggregate mixes, etc.

These additive salts, as they will be referred to hereinafter, are water-soluble salts of the type Me A in which Me represents the ammonium radical (NI-I4), an alkali metal, such as lithium, sodium or potassium or an alkaline earth metal, such as magnesium, barium or calcium; in which A represents a monoor divalent anion; and in which a and b indicate the molar proportions of Me and A required to form the respective salt.

Preperably, where Me is divalent (e.g., Mg++), A is monovalent. Most advantageously, both Me and A are monovalent, in which case a and b are each equal unity.

Examples of cations in operative additive salts are: the ammonium, lithium, sodium, potassium, magnesium, calcium and barium cations. Examples of corresponding anions are: the fluoride, chloride, bromide, iodide, thiocyanate, sulfate, acetate, propionate, benzoate, lactate, basic citrate and sulfonate anions. The corresponding operative additive salts are, for instance, ammonium chloride, ammonium sulfate, ammonium thiocyanate, sodium chloride, sodium thiocyanate, sodium acetate, various water-soluble low molecular weight sulfonates, such as sodium benzene sulfonate and sodium naphthalene-,B-sulfonate, lithium thiocyanate, lithium chloride, potassium chloride, potassium thiocyanate, sodium sulfate, calcium sulfate, calcium thiocyanate, calcium chloride, magnesium chloride and barium chloride.

I While all of the aforementioned water-soluble salt additives will tend to improve the quality and the performance of the emulsions of my invention, and, in particular, their pumping stability and mixing stability, some of them will be more suitable than others in enhancing a particular quality or performance property (or properties) of an emulsion, depending on the particular, more or less efiective quaternary nitrogen-containing emulsifier. Thus a chloride, such as ammonium chloride, will be more effective than a corresponding sulfate (NH SO in improving emulsion quality (lack of graininess, homogeneous texture, etc.), while the sulfate will tend to impart better plating. In fact, as a general rule, salts of monovalent anions are more beneficial to emulsion quality than salts of divalent anions, contemplated by my invention.

These additive salts employed in accordance with the present invention are preferably used in a smaller amount than the cationic emulsifier effective in preparing the cationic bituminous emulsion, and usually in amounts from about 0.01 to about 0.25%, based on the weight of finished emulsion. Again, however, more or less may be employed depending upon factors, such as the cost of the cationic quaternary nitrogen emulsifier, the nature and amount of the dispersed material, etc.

A particularly preferred group of operative salts is one of the ammonium and alkali metal thiocyanates, the addition of which in amounts from about 0.01 to about 0.25%, and preferably from about 0.025 to about 0.20% by Weight, based on the finished emulsion, markedly enhances stability of the cationic bituminous (asphalt) emulsion upon agitation, as by stirring, and in pumping.

Another remarkably satisfactory group of operative additive salts is formed by alkali metal acetates and propionates. When these low molecular weight carboxylates, and among them particularly sodium acetate, are present in the cationic bituminous emulsions of the invention in the aforementioned range of amounts of from about 0.01 to about 0.25% and preferably from about 0.025 to about 0.20% by weight, the mixing stability of cationic bituminous emulsions is markedly improved. In other words, their addition improves ability of mixing the emulsion with siliceous stone aggregate or sand and of depositing on the surface of this aggregate a perfect, durable and firmly adherent coating of the bituminous binder, such as an asphalt. At the same time, the ability of the emulsion to withstand agitation and particularly its ability to be pumped Without breaking down are likewise remarkably enhanced.

Likewise, chlorides of ammonium, alkali metal, and alkaline earth metal anions, when used in the same range of proportions (about 0.01 to about 0.25%, and preferably about 0.025 to about 0.20% by Weight), improve substantially the stability of cationic bituminous emulsions not only in storage, but also when subjected to agitation and, particularly, to pumping. Also the presence of these chlorides is noted to extend the mixing stability; that is, ability of being mixed with stone aggregate without too quick a breakdown.

The additive salts of my invention, and particularly the preferred ones, significantly improve the quality of cationic emulsions prepared with the aid of the aforedescribed emulsifiers and markedly enhance the performance qualities of these emulsions and/or their mechanical stability, i.e., stability while being mixed with the aggregate prior to being applied to the road surface.

The disperse phase of the emulsion is a bituminous material, such as an asphalt (which may be a natural asphalt or may be derived from the refining of petroleum as by steam refining and/or air blowing), gilsonite, coal tar or coal tar pitch. However, the disperse phase may be any other insoluble, thermoplastic, organic material which is emulsifiable in water by means of a cationic emulsifier, for example, parafiin wax, acrylic resins, polyethylene resins, Vistanex or alkyd resins.

The water and the bitumen may be employed in varying proportions, for example, about 30 to about 70 parts by weight of water and about 70 to about 30 parts by weight of bitumen, e.g., an asphalt, preferably from about 50 to about 70% by weight.

The principal emulsifying agent, which will frequently be the only active component of the emulsifier is a salt of a quaternary nitrogen base, containing the characteristic ionogenic group as defined hereinbefore in this specification.

The emulsifier material may consist entirely of an active cationic salt of a quaternary nitrogen base, or may also contain-some impurities, such as acyl chlorides and amines. It may be also employed in the form of a concentrated aqueous solution and may contain auxiliary stabilizers in amounts conventionally employed in the trade.

Among the available commercial emulsifier materials, the following may be employed for the preparation of cationic emulsions in accordance with the invention:

(1) ATM50. This is the trademark of a product of California Chemical Co., San Francisco, California, for N-alkyl benzyl-N,N,N-trimethyl ammonium chloride which has the following formula R c 2H5 in which R averages about 12 carbon atoms. As in the case of ATM-50, the compound ADE-5O contains minor amounts of the starting materials which, in this case, are alkyl benzyl chloride and N,N-diethyl-N-ethanol amine.

(3) Emcol 13-11. This is the trademark of a product of Emulsol Chemical Corporation of Chicago, Illinois, for N-alkyl benzyl-N,N,N-trimethyl ammonium chloride having the following formula wherein R averages about 12 carbon atoms.

(4) Hyamine 2389. This is the trademark of a product of Rohm and Haas Chemical Co., of Philadelphia, Pennsylvania, for N-alkyl methyl benZyl-N,N,N-trimethyl ammonium chloride which has the following formula wherein R averages about 12 carbon atoms.

(5) Arquad T. This is the trademark of a product of Armour and Company, Chemical Division, of Chicago, Illinois, for C C -alkyl trimethyl ammonium chloride which has the following formula wherein R is a long alkyl chain derived from fallow.

(6) Hyamine 1622. This is the trademark of a product of Rohm and Haas Chemical Co., of Philadelphia, Pennsylvania, for di-isobutyl phenoxyethoxy ethyl dimethyl benzyl ammonium chloride monohydrate of the formula (7) Arquad S. This is the trademark of a product of Armour and Company, Chemical Division, of Chicago, Illinois, for C -C alkyl trimethyl ammonium chloride which has the formula wherein R is a long alkyl chain derived from soybean oil.

7 (8) Quatrene AT. This is the trademark of a product of Textilana Corporation, of Hawthorne, California, for a quaternary nitrogen-containing chloride material of the formula wherein A is a C -alkyl chain derived from stearic acid and G is a polyoxyethylene group of approximately 5 oxyethylene units.

(9) Nalquat G-9-13. This is the trademark of Nalco Chemical Company of Chicago, Illinois, for 1-(2-hydroxyethyl)-2-heptadecenyl 1 (or 3) (4 chlorobutyl) imidazolinium chloride.

It is believed that minor amounts of the starting materials ordinarily are present in the aforementioned emulsifiers as impurities of no consequence to their operativeness according to the invention.

These and other suitable cationic emulsifiers may be employed in varying amounts, generally from about 0.25 to about 1.5%, and preferably from about 0.40 to about 1.5% of the active cationic component, based on the weight of the finished emulsion, although more or less may be employed depending upon factors such as the cost of the emulsifier, its effectiveness as an emulsifying agent, the amount of bitumen dispersed, etc.

The cationic bituminous emulsions prepared in accordance with the invention are eminently suitable for various applications in paving work. Ordinarily, the working pH of these emulsions ranges from about 4.0 to less than about 7.0 and preferably from about 4.5 to about 6.0. This pH permits of applying the cationic emulsions of the invention with success to hydrophilic, siliceous aggregates in sharp contrast With the known anionic asphalt emulsions characterized by an alkaline pH above the neutral point of 7.0, and preferably employed at a pH of from about 9.0 to 11.0 and higher. By the same reason, the cationic emulsions contemplated by the invention are distinguishable from and unlike the previously known asphalt emulsions stabilized with the proteins, for instance, emulsions stabilized with gelatin. These protein-type materials usually are insoluble at a pH of about 4.0-4.5 and higher and, obviously, are ineffective for stabilizing bituminous emulsions in the pH region from about 4.0 to the neutral point.

The many improvements due to the presence of the various salts introduced into cationic bituminous emulsions in accordance with my invention, in particular, improved emulsion quality and excellent performance of these emulsions are shown in the following illustrative examples and, in the case of chlorides, also by the accompanying drawing obtained by plotting the data observed in using ammonium chloride. In the following examples, the percentages of emulsfier are based on 100% active material.

EXAMPLE I This example is given to illustrate improvement resulting from the addition of chloride salts in the stability of cationic asphalt emulsions, prepared with quaternary nitrogen-containing emulsifiers, upon subjecting such emulsions to a pumping action as it occurs in transferring the emulsion from a storage tank to mixing and/ or application equipment. It also confirms improvement in the adhesion of the asphaltic binder to the aggregate.

An emulsion was prepared of 65 parts by weight of Boscan asphalt (a steam-refined Venezuelan asphalt having a penetration of 200/300), in parts of water employing ATM- as the emulsifier in the amount of about 0.3% based on weight of finished emulsion. Conventional emulsification technique was employed. To different lots of this emulsion were added varying amounts of ammonium chloride. A property denoted as pressability was determined for each of the lots. In determining pressability the following technique was employed:

A large nut is threaded onto a bolt which is rotated by a reversible motor equipped with a reversing switch to cause the bolt to spin first in one direction and then in the opposite direction. The nut is held in place by a metal container into which the emulsion under test is poured. The motor is started. Since the nut is held against rotation as the bolt spins first in one direction and then in the other, the nut will move up and down within the container, thereby simulating a pumping action. When the emulsion breaks due to the pumping operation, it will deposit asphalt on the threads of the bolt, thereby binding and hindering relative rotation of the bolt and nut. A torque is therefore applied to the container which increases until it rotates the container. When the container rotates, it opens a limit switch and thereby stops the motor. The lapsed time, which is shown on the ordinate scale of the accompanying drawing, is a measure of the resistance of the emulsion to the demulsifying effect of the pumping action. It is referred to as pressability.

It will be seen from the drawing that, by the addition of about 0.04 to 0.05% of ammonium chloride, the pressability of the emulsion was greatly improved.

Stone coating effectiveness was also improved by the addition of ammonium chloride. Thus, the Stone Coating Test described above was employed. The results of the Stone Coating Test are expressed as the extent in percent of total aggregate surface which remains coated with the binder after the water wash. Adhesion to more than 60% of the wet aggregate surface is considered satisfactory. It was found that a peak of stone coating effectiveness (-100%) was obtained with about 0.033% to 0.054% of ammonium chloride.

The results of the Pressability Tests dramatically demonstrated the criticality of the combination of components necessary for the preparation of emulsions in accordance with the invention. These cationic bituminous emulsions (asphalt-in-water, and the like), which are formulated using quaternary nitrogen-containing salt emulsifiers and the water-soluble salts of the particularly specified kind and in the particular effective amounts, were observed to withstand the destructive, demulsifying effect to agitation, as it occurs in pumping. This extended stability in pumping is in sharp contrast with the instability and immediate breakdown in pumping of similar bituminous emulsions prepared with primary aliphatic amine salt emulsifiers, despite the presence therein of like water-soluble salts of ammonium, alkali metal or alkaline earth metal anions. It establishes the practical superiority of the quaternary nitrogen-containing salt emulsifiers over the primary aliphatic amine salt emulsifiers in the emulsions comprising the aforementioned water-soluble additive salts, such as chlorides, acetates, thiocyanates, sulfates, in regard to actual application of these emulsions, permitting their handling after preparation and storage, pumping them from tanks through transfer lines into working equipment, all without the risk of premature breakdown and costly loss of the bituminous binder component.

The superiority of bituminous emulsions formulated according to my invention in the practical acid pH range, preferably from about 4.5 to about 6.9, clearly refutes unsubstantiated assumptions which may have equated quaternary nitrogen-containing salt emulsifiers with amine salt emulsifiers and, in particular, with primary aliphatic amine salt emulsifiers, such as stearyl amine hydrochloride, despite the well known differences in the solubility of these emulsifier salts.

EXAMPLE II The series of tests shown in this example further illustrates movements in emulsion properties, particularly in the adhesion of the bituminous binder to siliceous aggregate, when the emulsions prepared with quaternary nitrogen-containing emulsifiers further contain different watersoluble salts in accordance with the invention.

A siliceous, hydrophilic aggregate was employed. Emulsion was prepared from a steam-refined, 120-150 penetration asphalt derived from a California petroleum crude oil. Conventional emulsifying technique was employed to emulsify 65 parts by weight of the asphalt in about 35 parts by weight of water. The emulsifying agents employed were Hyamine 2389 and ADE-50, which were employed in varying amounts. Two series of emulsions were, therefore, prepared; one series having having Haymine 2389 as the emulsifying agent, and the other series having ADE-50 as the emulsifying agent. Two representative additive salts, a sulfate and a chloride,

10 has been broken, the adhesion of asphalt to the aggregate and mat strength, that is to say, the degree to which the particles of aggregate adhere together and resist separation. It is desirable in this test that maximum break, maximum adhesion and maximum of mat strength be exhibited,

First any free liquid is poured out, indicating whether any or a part of the emulsion did break. Then the remaining solid material in the can is dumped out on a metal screen. If it is in the shape of a big chunk or chunks rather than in the form of individually coated rock particles or chips, the mat strength is rated either as good or fair. By washing the material on the screen with a stream of distilled water, one may then estimate how much asphaltic binder is left adhering to the aggregate.

Table I Additive Salt (NH4)2SO4 percent WSD&P WSD&P

Hyamine 2389:

emulsion broke.

broken.

very poor bro N H401, percent operative in accordance with my invention, were added to these emulsions. The quality of each emulsion was judged by noting its color, (a brown color indicating a finer grained emulsion and a black color indicating a coarser grained emulsion) and by the results of the Sieve Test of ASTM D24455. The emulsion, in each instance, was allowed to stand overnight after its preparation and then was visually examined by stirring the contents of the storage flask or jar with a spatula, and observing the emulsion draining from the spatula as to its color and graininess. Any settlement at the bottom of the flask and any skinning on the surface of the emulsion was likewise qualitatively examined. The quality was then noted as poor, fair, or good. Also, a Wet Stone Dehydration and Penetration Test was employed. Results of these examinations and tests are set forth in Table I below, in which Q indicates quality and WSD & P indicates performance in the Wet Stone Dehydration and Penetration test.

The WSD & P test carried out as follows:

A can is filled with clean wet siliceous aggregate containing no fines. 100 grams of the test emulsion is poured over the aggregate, and the mixture is cured under cool, shady conditions. After one hour, the mixture is examined to determine the amount of emulsion which Q WSD A: P Q WSD dz P Q WSD & P

good poor+. do Do. i do fair.

broke very poor broke i.

Referring to Table I, wherever emulsion broke, the words Emulsion broke or the word broke appears. Wherever an emulsion broke, as indicated under the espective Q column, the WSD & P test was not carried out because there would be no purpose in doing so.

The following is apparent from an inspection of Table I:

In most cases, the addition of ammonium sulfate and/ or ammonium chloride improved either the quality of the emulsion, or its performance in the WSD & P test or both the quality and WSD & P performance. In some cases, the emulsion could not be prepared adequately under the conditions indicated. For example, 0.25 Hyamine 2389 was insufficient to prepare a stable emulsion, although greater quantities yielded emulsions of poor to fair quality.

Similar improvement were obtained in similar tests employing a /200 penetration San Ardo asphalt, which is a steam-refined asphalt from crude petroleum from the San Ardo field in California. Thus, with 0.33% Hyamine 2389 as the emulsifying agent, the emulsion (35% water, 65% asphalt) broke on agitation, but by including 0.03% ammonium sulfate, an emulsion was produced having a Q value of good and a WSD & P value of fair. With 0.25% Hyamine 2389, the emulsion broke on agitation but was improved by 0.03% ammonium sulfate to a Q of good and a WSD & P of good. Generally similar improvements were obtained with 0.33% ADE50 as emulsifier by adding 0.03% ammonium sulfate; by adding small quantities of ammonium chloride to emulsions made from the same San Ardo asphalt with I-Iyarnine 2389 as the emulsifier; and by adding small quantities of ammonium chloride to similar emulsions of an Inglewood 120-150 asphalt having Hyamine 2389 and ADE-50 as the emulsifier.

EXAMPLE III The test series described hereinafter illustrate the operativeness of representative salts from the group of thiocyanates particularly effective in accordance with my invention, namely, ammonium, sodium and potassium thiocyanates. Added in amounts from about 0.01 to about 0.25% and preferably from about 0.025 to about 0.20% by weight to cationic asphalt emulsions which have been prepared with quaternary nitrogen-containing salt emulsifiers, these thiocyanates are responsible for the simultaneous and substantial improvement of the properties of the emulsions. Specifically, the presence of these thiocyanates increases the emulsion stability during pumping (as shown by the Pressability data), improves stability while in storage (as shown by the Sieve Test data) and insures good adhesion of the asphalt binder to the stone aggregate.

Emulsions were prepared consisting of 70 parts by weight of Boscan 200/300 penetration asphalt and 30 12 ability Test and in the Stone Coating Test, and, furthermore, reduced foaming.

EXAMPLE IV This series of tests was carried out to determine whether or not addition of salts to the cationic asphalt emulsions, in accordance with my invention and within the range of amounts found by me to be operative in enhancing the pumping stability and the adhesion property, is accompanied by a lowering of the pH value of the emulsion.

Emulsions of 65% of Boscan asphalt, similar to that of Examples I and III have been prepared, emulsifying the asphalt in water by weight) with the aid of two representative cation-active emulsifying agents, namely, the aforementioned ADE-50 (0.5% by weight of the final emulsion) and Arquad T as a 50% solution (also 0.5% by weight of the emulsion). The pH values of the emulsifying water were 5.10 and 6.85, respectively. The pH of the resulting emulsions were determined potentiometrically. Three typical chlorides were introduced into the emulsions in the emulsifying water. These were ammonium chloride, sodium chloride and calcium chloride in amounts equal to 0.1, 0.5, and 1.0% by weight of the final emulsion. The results appearing in the following tabulation (Table III) unmistakably indicate that addition of salts, in accordance with the invention as described herein, has no significant effect on the pH of the emulsions and certainly, contrary to some previously published opinions, does not cause a lowering of the pH.

Table III [Emulsion pH] i No additive NHiC1, percent CaCh, percent NaCl, percent 0.1 0.5 1.0 0.1 0.5 1.0 0.1 0.5 1. Emulsion prepared with ADE-50 4.6 4.8 5.05 5.15 4.75 5.0 5.10 4.8 5.15 5. 20 Emulsion prepared with Arquad T-50 4.75 5.05 5.35 5.35 5.15 5. 5.50 5.2 5. 5. (50

One series of these emulsions EXAMPLE V parts by weight of water. contained 0.5% of ADE-50 as the emulsifier and a second series contained 0.4% of ADE50 as the emulsifier. The Sieve, Pressability and Stone Coating Tests above described were performed and the amount of foaming during mixing with aggregate during the Stone Coating Test was noted. Results are set forth in Table II below:

Table II Boscatn 200/300 pen. asphalt (parts by 70- 70 70--." 70.-- 70"... 70 70.-." 70.

\V ADE-50 (parts bywt.) 0.50 8.3g.-. 0.50--- 0.40--. 0.40..- 0.40." 0.40 0.40.

NaSON (parts by wt.) KSCN (parts by wt.) NELSON (parts by wt.) Water Sieve test some slight shot. shot. shot shot. Pressability test (seconds) 18 40.-. 7-..- Stonecoating test (adhesioninpercent) G0 100 90... 50 Foam during mixing in stone coating excessome slight. excestest. sive. sive.

ual 100 parts slight slight slight slight shot. shot. shot. shot. 30- 40. 70 65. slight none none excessive.

It is seen from the data in Table II that the addition of small quantities of sodium thiocyanate, potassium thiocyanate and ammonium thiocyanate elfected substantial improvements in the results of the Sieve Test, the Presssalts added to illustrate the operativeness of the invention were sodium naphthalene fl-sulfonate, barium chloride and calcium sulfate. A similar difficult-to-coat, hydrophilic, siliceous aggregate was again employed with this 13 series of emulsions in the Stone Coating Test described hereinbefore. The mixing stability of the emulsions (i.e. stability while mixing with the aggregate) was compared visually.

Table IV 14 Emulsion A, 0.036% by weight of potassium thiocyanate; emulsion B, 0.109% by weight of potassium thiocyanate; emulsion C, 0.03% by weight of sodium thiocyanate; emulsion D, 0.061% by weight of sodium Percent by weight of active in emulsifier material based on total emulsion Additive salt in percent by Weight based on total emulsion Mixing Stability Adhesion (percent of aggregate surface remaining coated) EXAMPLE VI In another test, more emulsions were prepared using 70 parts by weight of Boscan 200/300 penetration asphalt and 30 parts by Weight of water. The emulsifier was Nalquat G-9-13, that is, 1-(2-hydroxyethy1)-2-heptadecenyl-l-(or 3)-(4-chlorobuty1) imidazolinium chloride. The emulsifier was employed in an amount equal to 0.5% by weight of the total emulsion. Sodium acetate, as a preferred, readily available additive salt, in an amount of 0.2% by weight was added to the emulsion in accordance with the invention. The acetate-containing emulsion possessed an improved pumping ability due to reduced viscosity and mixed satisfactorily with the aggregate in the Stone Coating Test.

EXAMPLE VII In this test series again the advantages of adding an acetate or a propionate of sodium have been reconfirmed. An asphalt-in-water emulsion was prepared from 69 parts by weight of 200/300 penetrating Boscan asphalt, using 0.2% by weight of cetyltrimethyl ammonium bromide as the emulsifier, and was further treated with 0.1% by Weight, based on the total emulsion, of sodium acetate. This emulsion, likewise, displayed an improvement in pumping ability, the viscosity having been reduced t less than /5 of the viscosity observed in the absence of the acetate additive. Mixing times and adhesion were likewise improved.

EXAMPLE VIII In an additional test series again I employed emulsions of 70% by weight of Venezuelan (Boscan, 200/ 300 penetration) asphalt in water (30%), prepared with the aid of the cationic emulsifier ADE-50 (0.5% by weight), mentioned among the representative quaternary nitrogencontaining emulsifier salts. Sodium and potassium thiocyanates were added to four such emulsions (A, B, C and D), as follows:

thiocyanate. The final emulsions containing these thiocyanates, after they have been subjected to agitation for 30 minutes at 180190 F., had excellent appearance and displayed but a slight formation of asphalt shot (sedimentation).

EXAMPLE IX A series of emulsions consisting of parts by weight of 200/300 penetration Boscan asphalt and 30 parts by weight of Water was prepared with the aid of an emulsifier made up of two active cationic components, namely, 0.28 by weight, based on the total emulsion of Arqua-dS (50% active), and 0.33% by weight of Rosin Amine D, and enough HCl to react with the amine to a pH of 3.5. Arquad-S is a quaternary ammonium chloride in which the long alkyl chain is derived from soybean oil. Rosin Amine D is the trade name of a primary amine material manufactured and sold by Hercules Powder Company of Wilmington, Delaware. This primary amine, as indicated by its name, contains hydrocarbon radicals derived from talloil (rosin oil). To these emulsions there were added varying amounts, from 0.025 to 0.5 by weight of the emulsion, of sodium acetate in accordance with the invention. The so treated emulsions were then submitted to the Stone Coating Test, employing a dificult-to-coat hydrophilic, siliceous aggregate, ranging in size from /z" to l, with 5% of fines. Here the water has been applied five minutes after the completion of mixing. Mixing times were then observed and viscosities were determined.

Table V shows the results obtained in the Stone Coating Test (as adhesion in percent), the viscosity (SSE at 122 F.) and mixing times in minutes. The improvement in the mechanical (mixing) stability, in other words, in the ability of the emulsion to remain stable while being applied to the aggregate, thus permitting a satisfactory coating, isshown in Table V by the figures in Column designated Mixing Times.

Table V Additive salt Viscosity in Adhesion in Test runs in percent by SSF at 122 F. Mixing time in minutes percent Remarks 4 Asphalt residue 65%. N o

cutter stock added. 1 5% of light hydrocarbon cutter stock added. Emulsion failed to coat (7- 0.1 5% of light hydrocarbon cutter stock added. 0.025 100 Do. 0.05 100 D0. 0. 1 100 D0. 0. l 100 Do. 0.2 100 Do. 0.3 100 D0. 0.5 201 ,d0 100 Do.

* Too thick to measure l,000 SSF).

The data in Table V again clearly indicate that the addition of a salt in accordance with the invention results in a satisfactory stable coating on the aggregate (as shown by the values of adhesion), and, furthermore, markedly improves the mechanical stability of the emulsion. The fact that the mixing time available for an intimate mixing and coating of the aggregate with the emulsion is increased so markedly, represents a very valuable advan tage in those applications where the emulsions are mixed with the aggregate at the job site in the so-called motopaver equipment (described, e.g., in Bulletin MP-49 of Hetherington and Berner, Inc. of Indianapolis, Indiana), and the mix is thereafter immediately applied to the road bed. Furthermore, the addition of a salt, such as sodium acetate, as shown in the present test series, occasions a lowering of viscosity and improves thereby the pumping ability of the emulsions.

EXAMPLE X This test series was carried out to demonstrate again that the addition of acetates and propionates to cationic asphalt emulsions in accordance with the invention tends to impart to these emulsions a lower viscosity, to improve their stabilities in storage and in pumping, and to assure effective mixing thereof with, and coating of hydrophilic siliceous aggregates.

In the tests of similar emulsions of 70 parts by weight of 200/300 penetration Boscan asphalt and parts by weight of water, using about 0.4% by weight of Arquad T as the emulsifier, addition of sodium acetate in the same range of amounts from 0.025 to 0.5% by Weight of the emulsion, shows an improvement (lengthening) of mixing times, a satisfactory coating of the aggregate, and an adequate stability for surviving the pumping action before the actual application of the emulsion in paving work.

The aforegiven description, illustrated by the experimental data, makes it apparent that a new and effective means has been provided for improving cationic emulsions with respect to emulsion quality (e.g., more uniform particle size and the descreased proportion of large or oversized particles), and with respect to performance qualities, such as pumping qualities, Stone Coating (adhesion), etc.

I claim:

1. An oil-in-water type cationic asphalt emulsion for use in paving applications, characterized by its ability to be pumped without breaking down and by remaining stable for at least five minutes on being mixed with siliceous stone aggregate, said emulsion consisting essentially (a) from about 30 to about percent by weight of asphalt as the dispersed phase;

(b) from about 0.25 to about 1.5 percent by weight of a quaternary nitrogen-containing compound characterized by the general formula in which the organic radicals R R R and R are alkyl, alkenyl, hydroxyalkyl, arylakyl, and alkylaryl radicals of 1 to 24 carbon atoms, and heterocyclic groups of 4 to 10 carbon atoms, in which from 2 to 3 of the nitrogen valences are shared by 2 carbon atoms in a single heterocyelic group, and X is an anion selected from the group consisting of chloride and bromide anions; (c) from about 0.01 to about 0.25 percent by weight of a water-soluble alkali metal acetate; (d) water as the continuous phase in an amount to make up percent. 2. An oil-in-water type cationic asphalt emulsion as defined in claim 1, wherein the water-soluble alkali-metal acetate is sodium acetate.

References Cited by the Examiner UNITED STATES PATENTS 1,960,115 5/1934 Loebel 106-277 XR 2,191,295 2/1940 Dohse et al 106-273 XR 2,615,851 10/1952 Manzer 252-3115 FOREIGN PATENTS 702,818 1/ 1954 Great Britain.

JULIUS GREENWALD, Primary Examiner.

ALBERT T. MEYERS, Examiner.

Claims

1. AN OIL-IN-WATER TYPE CATIONIC ASPHALT EMULSION FOR USE IN PAVING APPLICATIONS, CHARACTERIZED BY ITS ABILITY TO BE PUMPED WITHOUT BREAKING DOWN AND BY REMAINING STABLE FOR AT LEAST FIVE MINUTES ON BEING MIXED WITH SILICEOUS STONE AGGREGATE, SAID EMULSION CONSISTING ESSENTIALLY OF: (A) FROM ABOUT 30 TO ABOUT 70 PERCENT BY WEIGHT OF ASPHALT AS THE DISPERSED PHASE; (B) FROM ABOUT 0.25 TO ABOUT 1.5 PERCENT BY WEIGHT OF A QUATERNARY NITROGEN-CONTAINING COMPOUND CHARACTERIZED BY THE GENERAL FORMULA