Patent Description:
Recent technical challenges facing the asphalt industry have created opportunities for the introduction of agriculture-based products for the overall performance enhancement of asphalt. Such performance enhancements may include, for example but aren't limited to, anti-strip, organophilization, oil field, and compaction aid applications. <CIT> discloses the use of lecithin as emulsifier for bitumen applications.

The present invention provides a method, comprising obtaining a lecithin-containing material derived from a crude refining stream being a plant-based gum, comprising <NUM>-<NUM> wt% acetone insoluble matter, <NUM>-<NUM> wt% free fatty acid, and less than <NUM> wt% water with the remaining balance being oil; adding a fatty acid source to the lecithin-containing material to obtain a lecithin fatty acid blend having an acid value of <NUM> to <NUM> KOH/g; and incorporating the lecithin fatty acid blend into asphalt applications, wherein the lecithin fatty acid blend is added to an asphalt binder thereby forming a mixture, wherein the amount of the lecithin fatty acid blend ranges from <NUM> to <NUM> wt% of the mixture.

"Acid Value" (AV) is a measure of the residual hydronium groups present in a compound and is reported in units of mg KOH/gram material. The acid number is measured according to the method of AOCS Cd 3d-<NUM>.

"Acetone Insoluble Matter" (AI) determines the acetone insoluble matter in a sample and is reported as % per AOCS method Ja <NUM>-<NUM>. The phosphatides are included in the acetone-insoluble fraction.

"Fatty Acid" is defined as a carboxylic acid having a chain of at least six carbon atoms. "Gums" utilized herein are derived from plant-based materials, preferably corn, soy, canola (rapeseed), and cottonseed and are comprised of water, acetone insoluble matter (mostly phosphatides), free fatty acids, and oil.

"Lecithin" is a complex mixture of acetone-insoluble phosphatides combined with various amounts of other substances, such as triglycerides, fatty acids, and carbohydrates. Lecithin contains at least <NUM>% of acetone insoluble matter.

"Phosphatides" include phosphatidic acid, phosphatidylinositol, phosphatidylethanolamine, phosphatidylcholine, and other phospholipids.

"Reaction" utilized herein primarily refers to the process of blending a lecithin-containing material and a fatty acid or carboxylic acid source, optionally with additional heat.

The lecithin-containing material utilized herein is derived from crude refining streams containing fatty acids and phosphatidyl material. In some aspects, the lecithin-containing material may be gums resulting from a degumming processes, for example, but not limited to, water degumming, caustic and acidic degumming, phospholipase A and phospholipase C degumming, or other enzymatically produced gums (one skilled in the art would know that phospholipase A would produce lyso lecithin).

It shall be understood that despite the various aspects, the lecithin-containing material preferably comes from crude products rather than food-grade products. Thus, crude products that are dark in color, odorous, or otherwise undesirable for food and personal care applications are preferred sources for the lecithin-containing material (however, food-grade lecithin may also be used as the lecithin-containing material).

Regardless of the source, the lecithin-containing material comprises a small amount of water, phosphatides (typically defined by acetone insoluble matter), free fatty acids, and oil. The lecithin-containing material comprises less than <NUM> wt% water ( preferably less than <NUM> wt%, less than <NUM> wt%, and less than <NUM> wt%), between <NUM> wt% and <NUM> wt% acetone insoluble matter (mostly phosphatides), between <NUM> wt% and <NUM> wt% free fatty acids ( preferably between <NUM> wt% and <NUM> wt%, and more preferably about <NUM> wt%), with the remaining balance being oil. Note that moisture (water) content is determined using AOCS method Ja 2b-<NUM> and acetone insoluble matter is determined using AOCS method Ja <NUM>-<NUM>.

It shall be understood that the preferred acid value depends on the source used to derive the lecithin-containing material.

One or more fatty acid sources (in addition to the fatty acid already present in the starting lecithin-containing material) is added to the lecithin-containing material to obtain a lecithin fatty acid blend. It shall be understood that the amount of fatty acid source added to the lecithin-containing material will directly depend on the amount of fatty acid already present in the lecithin-containing material. For example, lecithin-containing material having a high amount of fatty acid does not require as much addition of a fatty acid source as a lecithin-containing material having a low amount of fatty acid. It shall also be understood that, if desired, the fatty acid source may be used to further dry the lecithin-containing material as described in copending <CIT>) and <CIT>), collectively filed as PCT Application No. <CIT>.

Many types of fatty acid sources may be used, including both natural and petrochemical fatty acid sources. For cost effective reasons, fatty acids derived from crude waste streams, for example deodorized distillate streams, vegetable oils, and recovered corn oil streams (and derivatives thereof, for example, polymerized corn oil streams), are desirable fatty acid sources as well as fatty acids derived from waste streams containing phosphatides and other impurities (e.g., sterols, tocopherols, starches, waxes, etc.). However, fatty acids in their natural or synthetic form may also be utilized herein as the fatty acid source. The fatty acid source may also derived from a combination of various waste streams, a combination of various natural or synthetic oils, or a combination of both waste streams and natural/synthetic oil.

In preferred aspects, the fatty acid source has a viscosity ranging from <NUM> to <NUM> cSt at <NUM>, and more preferably <NUM> to <NUM> cSt at <NUM>. In further preferred aspects, the fatty acid source may be deodorized distillates (e.g. a distillate that is solid at <NUM>; <NUM> cSt at <NUM>), and products based on recovered corn oil (typically <NUM> cSt at <NUM>).

The lecithin-containing material and fatty acid source react until desirable characteristics, described below, and a homogenous blend of lecithin-containing material and fatty acid source are achieved. An optional elevation in temperature between about <NUM> and <NUM> (and more preferably around about <NUM>) may be introduced. In some cases, this reaction temperature may cause a darkening in color, and more specifically an increase in Gardner color of at least <NUM> unit, and/or a slight reduction in AI, which may be desirable for certain industrial-grade end-use applications.

Upon completion of the reaction, the resulting product is a resulting lecithin blend product with the following characteristics:.

The resulting lecithin blend product may be used to compatibilize inorganic materials into an oleophilic phase. Specifically, the resulting lecithin blend is incorporated into various asphalt applications (roofing, coatings, roads), for example as an anti-strip, surfactant, compaction aid additive, asphalt emulsifier, or as a dispersant of granulate and particulates in organophilic binders (asphalt roofing shingles) wherein the granulate may include but is not limited to calcium carbonate, mineral aggregates, and clay. Furthermore, the asphalt use may comprise hot mix asphalt (HMA), warm mix asphalt (WMA), asphalt emulsions or invert emulsion applications, or cold patch (solvent cut back) applications. The asphalt may also include additional additives or components required for the respective application.

Some end-use applications are explained in further detail below.

For the purpose of this invention, asphalt, asphalt binder, and bitumen refer to the binder phase of an asphalt pavement. Bituminous material may refer to a blend of asphalt binder and other material such as aggregate or filler. The binder used in this invention may be material acquired from asphalt producing refineries, flux, refinery vacuum tower bottoms, pitch, and other residues of processing of vacuum tower bottoms, as well as oxidized and aged asphalt from recycled bituminous material such as reclaimed asphalt pavement (RAP), and recycled asphalt shingles (RAS).

The resulting lecithin blend product may be used as an anti-stripping agent in asphalt applications. Without being bound to any theory, it is believed that the fatty acid and phosphatidyl material in the lecithin blend product synergistically interacts with moisture, and/or calcium, or other metal content of the substrate which consequently enhances adhesion between the binder and the substrate.

The lecithin blend product described herein is thoroughly mixed with an asphalt binder. The lecithin blend product /asphalt binder mixture is mixed until a homogenous product is reached (typically, the mixture may be heated between <NUM>-<NUM> and agitated to facilitate a homogenous blend). The mixture comprises <NUM>-<NUM> wt % of the lecithin blend product with the balance being asphalt binder. The resultant processed lecithin blend product /asphalt binder mixture is then typically mixed at approximately <NUM>% use level with an aggregate substrate, or according to the mix design called for by the road manufacturer.

Asphalt pavements require a minimum amount of energy to be produced and compacted. This energy is provided through a combination of heat and mechanical energy through use of roller compactors. Thus additives allowing for reduction in the required compaction energy to achieve target mixture density can enable a reduction of the compactor passes or the temperature, thus enabling an increase in the maximum haul distance of the asphalt mixture from the plant to the job site.

The different mechanisms through which such compaction aid additives function may include increased lubrication of aggregates during asphalt mixture compaction, reduction of the binder viscosity at production temperatures, and better coating and wettability of the aggregates. Thus a diverse range of chemicals and additives may exhibit one or more of the properties attributed to compaction aids when added to an asphalt mixture.

The lecithin blend product described herein can be used as a compaction aid, to achieve a decrease in the required compaction energy through increase in aggregate lubrication and aggregate wettability. In such an application the additive would be used at dosages preferably in the range of between about <NUM> and <NUM>% by weight of the bitumen.

Lecithin may be used as a reagent in the manufacture of organophilic clays and as a beneficial additive to invert drilling mud formulation in which these clays are utilized. Further, in these invert mud formulations fatty acids may be used as primary emulsifiers.

The following examples are presented to illustrate the present invention and to assist one of ordinary skill in making and using same. The examples are not intended in any way to otherwise limit the scope of the invention.

Asphalt mixtures were produced using an aggregate and bitumen known to be highly susceptible to moisture damage. The aggregate was sampled from a quarry in Lithonia, Georgia. The mixture was designed to meet a very common Georgia Department of Transportation mixture design requirement for a <NUM> maximum nominal aggregate size. The uncompacted mixture was allowed to rest for <NUM>±<NUM> hrs at ambient room temperature conditions before being subjected to <NUM>±<NUM> hr of oven aging at <NUM> before compaction to <NUM>±<NUM>% air voids using a gyratory compactor. The mix design was based on Superpave specifications as defined by AASHTO R30 and GDOT mixture specifications. The asphalt content was <NUM>% by weight of the mixture, the Voids in Mineral Aggregate (VMA) were <NUM>, <NUM>% by volume, and the Voids Filled with Asphalt (VFA) was <NUM>% by volume of the mixture. These values were targeted for all the versions of the mixture.

Generally the lecithin blends were produced by charging the lecithin and the fatty acid source at the dosage required to achieve the target acid value in a round bottom reactor. The lecithin used has an AI value ranging from <NUM>-<NUM>%. The blend was heated to <NUM>-<NUM> (temperature exceeding the melting point of the fatty acid) and agitated for <NUM> hour. Blends #<NUM> and #<NUM> followed this procedure. Soy lecithin and food grade soy fatty acid were used as the blend components. Blends #<NUM> and #<NUM> were comprised of soy lecithin and deodorized distillate, heated to <NUM>-<NUM> and agitated for <NUM> hr.

In all examples, addition of the lecithin blend to the bitumen was by heating the bitumen to <NUM> for approximately <NUM> hr, adding the desired dosage of the lecithin blend and agitated until full uniformity was achieved. Due to the high level of asphalt compatibility, required asphalt blend times were less than <NUM> minutes in the laboratory.

In order to evaluate the effect of adding lecithin blend as an anti-stripping additive, the mixtures were evaluated following the AASHTO T283 standard procedure. The bitumen was treated with <NUM>% of the lecithin blends by weight of the bitumen and used to produce sets of <NUM> compacted mixture samples that were <NUM> in diameter and <NUM> in thickness using the previously described mix design procedure for every antistrip. Three of the <NUM> samples were tested for tensile strength using indirect tensile strength ratio (TSR) procedure on a Marshall Press Apparatus manufactured by Pine Instrument Company. The other three samples were subjected to <NUM>-<NUM>% saturation of the internal voids with water and placed in a freezer for <NUM> hrs followed by <NUM> hrs of conditioning in a <NUM> water bath. All <NUM> samples were placed in a <NUM> water bath for <NUM> hrs prior to testing for indirect tensile strength at a rate of <NUM>/min to achieve temperature equilibration. The tensile strength values before and after conditioning and the ratio between the two values are used as an indication of the moisture damage resistance, with higher ratio values indicating higher resistance to moisture damage, and thus better performance from the incorporated anti-stripping additive.

Using the described procedure, lecithin blends with varying ratios of fatty acid were tested and compared to the control (un-treated) mixture. The different blends are characterized in terms of the Acid Value (AV). The results are shown in Table <NUM> and <FIG>.

By plotting the data from Table <NUM> by Acid Value, a trend is observed based on which the tensile strength ratio initially increases with the addition of the Acid Value to a maximum value, before subsequently decreasing as the Acid Value is further increased. The results show that an "optimum" blend proportion can be achieved based on the Acid Value. This optimum value is expected to vary based on the raw material sources and the bitumen and aggregate used in the mixture design.

Asphalt mixtures prepared as described in Example <NUM> were analyzed in terms of compactability by calculating the percent densification (reduction in sample height) with each gyration in the Superpave gyratory compactor used in accordance to AASHTO R35, as shown in <FIG>. The percent densification at <NUM> gyrations was quantified as a point of comparison between samples treated with lecithin blends containing different levels of fatty acid incorporation. The results are shown in Table <NUM>.

The results show that a statistically significant trend exists between the acid value of the lecithin blend and the beneficial contribution of the blend as a "compaction aid" additive. Analysis of Variance was performed on the results from the three analyzed replicates, showing a very high statistical significance (p-value < <NUM>). <FIG> shows that increasing the acid value improved the densification of the mixture.

Polyphosphoric acid (PPA) may be added at <NUM> to <NUM>% dosages by weight of the bitumen in order to increase the stiffness of the bitumen. Concerns exist in the industry with use of amine-based antistrip additives in conjunction with polyphosphoric acid with regards to neutralization of the effects of the additives in the bitumen.

Asphalt mixtures prepared following the method described in Example <NUM>, were tested using the Tensile Strength Ratio procedure following AASHTO T283 and compared in order to validate applicability of the antistrip material when used in bitumen modified with polyphosphoric acid. Table <NUM> shows a summary of the results.

The results shown in Table <NUM> and compared in <FIG> show that the presence of polyphosphoric acid did not lead to adverse effects on the ability of the lecithin blend to improve the moisture damage resistance.

A PG64-<NUM> base binder from the Flint Hills refinery was annealed for <NUM> hour at <NUM> after which <NUM>% by weight of <NUM>% Polyphosphoric Acid (PPA) was added and homogenized. This was followed by the addition of <NUM>% by weight of Blend #<NUM> (from Example <NUM>). A second sample was prepared with addition of <NUM>% Blend #<NUM> additive and no PPA. A control sample was also prepared of the PG64-<NUM> asphalt without any additives. The asphalt binders were stored in a <NUM> oven in closed containers for the period of <NUM> days and mixed daily.

Samples were evaluated at the onset, after <NUM> days, <NUM> days, and <NUM> days of storage in the <NUM> oven using a boiling test in accordance to ASTM D3625, in which aggregates were coated with <NUM>% by weight of asphalt, allowed to condition at <NUM> for <NUM> hrs, and then subjected to boiling for <NUM> minutes. The number of uncoated aggregates was counted to get an approximate quantitative measure of the percent of unstrapped aggregate for each binder type after the completion of the boiling test. The results are shown in the Table <NUM>.

Claim 1:
A method, comprising:
(a) obtaining a lecithin-containing material, comprising <NUM>-<NUM> wt% acetone insoluble matter, <NUM>-<NUM> wt% free fatty acid, and less than <NUM> wt% water with the remaining balance being oil;
(b) adding a fatty acid source to the lecithin-containing material to obtain a lecithin fatty acid blend having an acid value of <NUM> to <NUM> KOH/g; and
(c) incorporating the lecithin fatty acid blend into asphalt applications, wherein the lecithin fatty acid blend is added to an asphalt binder thereby forming a mixture, wherein the amount of the lecithin fatty acid blend ranges from <NUM> to <NUM> wt% of the mixture,
wherein the lecithin-containing material is derived from a crude refining stream, wherein the crude refining stream is a plant-based gum.