FIELD OF THE INVENTION

The invention relates to ammonium sulfate-based water conditioners useful for agricultural formulations.

BACKGROUND OF THE INVENTION

Ammonium sulfate is a well-known fertilizer for alkaline soils. It is also used to bind calcium, iron, and other metals to improve the efficacy of water-soluble herbicides, insecticides, and fungicides, particularly weak-acid herbicides such as glyphosate, glufosinate, and 2,4-D. When combined with certain classes of surfactants, especially alkylpolysaccharides, ammonium sulfate functions as an effective water conditioner for agricultural compositions.

Fatty amine oxides are well known and commercially available surfactants. Stepan Company, for example, sells AMMONYX ^® LO, a mixture of C12 and C fatty amine oxides (primarily N,N-dimethyl-N-dodecylamine-N-oxide), and AMMONYX ^® DO, a mixture of Cs and C10 fatty amine oxides (primarily N,N-dimethyl-N-decylamine-N-oxide).

U.S. Pat. No. 5,356,861 describes glyphosate formulations that include water, ammonium sulfate, an alkylpolysaccharide, and an anti-foaming agent. The reference indicates that the alkylpolysaccharide enables dissolution of an increased concentration of the ammonium sulfate in the herbicidal blend (col. 3, II. 34-37).

U.S. Pat. No. 5,945,377 suggests combining glyphosate or glufosinate with ammonium sulfate and a monosaccharide (e.g., corn syrup or fructose).

EP 0274369 describes glyphosate-ammonium sulfate herbicidal formulations that include a quaternary ammonium salt, which, according to the reference, can include amine oxides such as N-lauryl-N,N-dimethylamine-N-oxide. Example II shows an IPA glyphosate formulation with 27.1 wt.% ammonium sulfate and 13.4 wt.% of N-lauryl-N,N- dimethylamine-N-oxide. No amine oxide blends are described.

U.S. Pat. No. 6,228,807 discloses many glyphosate formulations that include ammonium sulfate as a component, but none with both ammonium sulfate and an amine oxide surfactant blend. U.S. Pat. No. 6,645,914 describes surfactant-ammonium sulfate adjuvants in which the surfactant is a liquid amphoteric iminodipropionate. The reference explains that ammonium sulfate “overcomes the antagonistic effect of sodium, calcium, and magnesium ions from hard water” and may “increase herbicide absorption.” Blends of amine oxide surfactants are not suggested.

U.S. Pat. No. 7,666,242 describes combinations of ammonium sulfate, an alkylpolysaccharide, and a sugar as adjuvant blends for spray application. Amine oxides are not suggested.

Although most commercial ammonium sulfate-based water conditioners contain alkylpolyglucoside surfactants, formulators appreciate that these water conditioners often have limited compatibility with common agricultural actives, low storage stability, and excessive foaming problems. The industry would therefore benefit from the availability of ammonium sulfate-based water conditioners based on surfactants or surfactant blends that avoid these limitations of alkylpolyglucosides. Ideally, the surfactants would already be articles of commerce approved for use in agriculture by applicable regulatory agencies.

SUMMARY OF THE INVENTION

In one aspect, the invention relates to a water conditioner composition useful for agricultural formulations. The composition comprises ammonium sulfate, water, and a fatty amine oxide blend. The compositions comprise 30 to 50 wt.% of ammonium sulfate and 2 to 10 wt.% of the fatty amine oxide blend. The blend comprises a C12-C14 fatty amine oxide and a Cs-C-io fatty amine oxide. The weight % amounts are based on the amount of water conditioner composition. In some aspects, the compositions include an antifreeze agent., a secondary surfactant, or both. In other aspects, the invention includes agricultural formulations that comprise a weak acid-based herbicide (e.g., glyphosate, glufosinate, 2,4-D, or dicamba) and the water conditioner compositions described above.

We surprisingly found that among many possible alternative surfactants, commercially available fatty amine oxides are highly compatible with the levels of ammonium sulfate needed for effective water conditioning. The amine oxide blends impart considerable flexibility in formulating water conditioners that resist separation for weeks at elevated (e.g., 54°C) and cold (e.g., 4°C or -15°C) temperatures. Surprisingly, ammonium sulfate-based water conditioners having a blend of the fatty amine oxides provide valuable stability advantages when compared with formulations based on a single fatty amine oxide. Compared with water conditioners that contain alkylpolyglucosides, those formulated with the fatty amine oxide blends have reduced foaming problems and excellent wetting properties at relatively low surfactant concentration, thus demonstrating both performance and cost advantages.

DETAILED DESCRIPTION OF THE INVENTION Water conditioners

In some aspects, the invention relates to water conditioner compositions useful for agricultural formulations. The water conditioners comprise ammonium sulfate, water, an optional antifreeze agent, and a fatty amine oxide blend. Ammonium sulfate

Agricultural-grade ammonium sulfate is available from many suppliers. In general, the purity level is not crucial. Suitable water conditioner compositions will comprise 30 to 50 wt.%, or 30 to 40 wt.%, or 33 to 35 wt.% of ammonium sulfate, based on the amount of water conditioner composition.

Blend of fatty amine oxides

The water conditioner compositions comprise 2 to 10 wt.%, or in some aspects 3 to 8 wt.%, based on the amount of water conditioner composition, of a fatty amine oxide blend. The blend comprises a C12-C14 fatty amine oxide and a Cs-C-io fatty amine oxide. Suitable C12-C14 fatty amine oxides and Cs-C-io fatty amine oxides are available commercially from Stepan Company as AMMONYX ^® LO and AMMONYX ^® DO, respectively. AMMONYX ^® LO is principally N,N-dimethyl-N-dodecylamine-N-oxide (a C12 fatty amine oxide, also known as “lauramine oxide”) with some N,N-dimethyl-N- tetradecylamine-N-oxide. AMMONYX ^® DO is principally N,N-dimethyl-N-decylamine-N- oxide (a C10 fatty amine oxide) with some N,N-dimethyl-N-octylamine-N-oxide. The weight ratio of C12-C14 fatty amine oxide and a Cs-C-io fatty amine oxide components in the blend can vary over a wide range. In some aspects, the C12-C14 fatty amine oxide is the major component, although we found that water conditioner compositions having only the C12-C14 fatty amine oxide present are considerably less effective providing storage stable water conditioners than conditioner compositions that include both Cs-C-io and C12-C14 fatty amine oxides (see results in Tables 4-6 versus results in Table 7). Thus, in some aspects, the weight ratio of C12-C14 fatty amine oxide to C8-C10 fatty amine oxide is within the range of 10:1 to 1 :1. In other aspects, the weight ratio of C12-C14 fatty amine oxide to Cs-C-io fatty amine oxide is within the range of 4:1 to 1 :1.

Water

The water conditioner compositions also contain water in an amount effective to solubilize the ammonium sulfate, antifreeze agent, fatty amine oxide blend, and any other components. Typically, the amount of water ranges from 25 to 68 wt.%, 30 to 65 wt.%, or 45 to 60 wt.%, based on the amount of water conditioner composition.

Antifreeze agent

Optionally, the water conditioner compositions comprise 2 to 8 wt.%, or 3 to 7 wt.%, or 4 to 6 wt.%, based on the amount of water conditioner composition, of an antifreeze agent. The antifreeze agent, when used, helps to minimize or prevent the formation of precipitates or crystals of ammonium sulfate and/or agricultural active (following combination of the water conditioner composition with the agricultural active). Suitable antifreeze agents are well known. In some aspects, the antifreeze agent is a C2-C6 glycol. Suitable antifreeze agents include, for example, glycerin, ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, hexylene glycol, and the like, and mixtures thereof. Glycerin and propylene glycol are preferred.

Other components The water conditioners can include other components such as secondary surfactants (nonionic surfactants, anionic surfactants, cationic surfactants, amphoteric surfactants, zwitterionic surfactants), solvents, pH-adjusting agents, anti-foaming agents, chelating agents, or the like. In some aspects, the water conditioners consist of or consist essentially of ammonium sulfate, the fatty amine oxide blend and water. In other aspects, the water conditioners consist of or consist essentially of ammonium sulfate, the fatty amine oxide blend, an antifreeze agent, and water.

Agricultural formulations

In some aspects, the invention includes agricultural formulations that comprise a weak acid-based herbicide and the water conditioner compositions described above. Suitable weak acid-based herbicides include compositions having weakly acidic protons. Many weak-acid herbicides are organic compounds that have carboxylic acid groups, phosphoric acid groups, or other relatively acidic protons. Classes of weak-acid herbicides include, for example, glyphosates, glufosinates, phenoxycarboxylic acids (e.g., 2,4-D, MCPA, MCPP, 2,4-DB, 2,4-DP), halobenzoic acids (e.g., dicamba), pyrimidine or pyridine carboxylic acids or carboxamides (e.g., aminocyclopyrachlor, picloram, imazethapyr, cyclopyralid, diflufenican), sulfonylureas (e.g., metsulfuron methyl), and the like, and combinations thereof.

The following examples merely illustrate the inventive subject matter. Many similar variations within the scope of the claims will immediately be apparent to those skilled in the art.

Compatibility of Ammonium Sulfate with Surfactants

For use in water conditioning, ammonium sulfate is generally formulated as an aqueous solution at about 34 wt.% of (NH bO^ A series of commercially available surfactants is combined at 5 or 10 wt.% surfactant with 34 wt.% ammonium sulfate to identify surfactants having adequate compatibility. Alkylpolyglucosides, which are compatible and commonly used in ammonium sulfate-based water conditioners, are not tested. In each case, ammonium sulfate is gradually added with good mixing to an aqueous solution of the surfactant. As shown in Table 1, relatively few classes of the screened surfactants are considered suitable for use based only on compatibility.

Shake foam test A drawback of alkylpolyglucosides (APG) as surfactants for ammonium sulfate- based water conditioners is their tendency to produce stable foams. To compare the foaming properties of water conditioners made using amine oxide surfactants with those made using APG, the properties of both formulations are evaluated using the shake foam test. Aqueous solutions containing 34 wt.% of ammonium sulfate and 56 wt.% of water are prepared. A comparative solution contains 10 wt.% of GLUCOPON ^® 420-UP alkylpolyglucoside surfactant (product of BASF). A test solution contains 3.5 wt.% of AMMONYX ^® LO surfactant, 1.5 wt.% of AMMONYX ^® DO surfactant, and 5.0 wt.% of semi-refined glycerin.

A 100-g portion of the solution is carefully transferred to a 500-mL graduated cylinder. The cylinder is stoppered and mechanically inverted ten times, then allowed to settle for 15 s. The initial foam height is recorded. After 5 min., foam height is recorded again. Two trials are performed for each mixture. Results appear in Table 2.

As shown in Table 2, the ammonium sulfate solution formulated with the amine oxide blend generates less foam volume than the solution formulated with the APG surfactant. Additionally, and the resulting foam begins to disintegrate more quickly with the amine oxide blend.

Draves wetting comparison

Draves wetting experiments are performed generally as described in ASTM D2281 -68. “Rapid” wetting is considered to be less than about 40 seconds. For the control experiment, the ammonium sulfate mixture with GLUCOPON ^® 420-

UP prepared as previously described is diluted with water to 2.5 wt.% of its original concentration.

Various solutions containing 34 wt.% of ammonium sulfate, 56 wt.% of water, and 10 wt.% of a mixture of AMMONYX ^® LO, AMMONYX ^® DO, and glycerin as shown in Table 3 are prepared. Each of these solutions is diluted to 2.5 wt.% of its original concentration for use in the wetting test.

Similar solutions are prepared using propylene glycol instead of glycerin. These solutions generally give Draves wetting results in the 20-50 second range.

The results demonstrate excellent wetting properties for the tested and control formulations. However, wetting is as good or better in Formulations A-F with only 3-6 wt.% surfactant in the original mixture versus 10 wt.% APG in the control formulation, a potential cost savings when using the amine oxide blend. Because large amounts of surfactant are used in agricultural applications, small differences in the amount used can translate into a large cost differential.

Stability testing To evaluate the ability of amine oxide blends to impart storage stability to ammonium sulfate-based water conditioners, ammonium sulfate is combined at 34 wt.% with water and various combinations of AMMONYX ^® LO, AMMONYX ^® DO, and semi- refined glycerin. The mixtures are prepared and held for 14 days at 54°C, 25°C, 4°C, or -15°C. Samples are inspected and rated for stability in comparison with a control sample containing 10 wt.% of AMMONYX ^® LO. The control sample is stable for 14 days at room temperature, but separation is apparent at the other tested temperatures. Ideally, no separation is observed at any of the temperatures.

As shown in Table 4, the 34 wt.% ammonium sulfate water conditioners containing combinations of AMMONYX ^® LO, AMMONYX ^® DO, and semi-refined glycerin are stable at all tested temperatures over a wide range of surfactant combinations and 3 to 6 wt.% amine oxide content. No separation is observed in any sample. In contrast, without the AMMONYX ^® DO also present (control sample), separation occurs when the samples are either heated or chilled.

Table 5 illustrates that similar excellent results can be achieved when 7 to 7.5 wt.% of propylene glycol is used instead of glycerin. Thus, at least in some aspects, a larger proportion of propylene glycol may be needed to get the same degree of compatibility observed with glycerin.

As shown in Table 6, other C2-C4 glycols (ethylene glycol, diethylene glycol) can be used alone or in combination with propylene glycol or glycerin to give stable ammonium sulfate-based water conditioners. In some samples, the most stressed conditions of -15°C promoted crystallization in some samples, but the overall results still exceed those seen with the control sample containing only AMMONYX ^® LO.

Table 7 summarizes the results of testing with other comparative formulations. Each of Comparative Examples 28-36 has 34 wt.% of aqueous ammonium sulfate and AMMONYX ^® LO as the only amine oxide. Although some samples were better than the control sample, the proportion of glycerin or propylene glycol can be varied without success in making a formulation that is stable at all tested temperatures. It is apparent that a blend of AMMONYX ^® LO with AMMONYX ^® DO is desirable for producing stable ammonium sulfate-based water conditioners.

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The preceding examples are meant only as illustrations; the following claims define the scope of the invention.

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