Patent Grant
7341981
The invention relates to spray compositions having an aqueous spray medium, an active ingredient, and a deposition control agent. The inventions relates more particularly to improvements of such compositions when they comprise a surfactant.
A spray composition is used for delivering an active ingredient onto a target, in the form of droplets. The composition is spayed (forming droplets), by using appropriate means, and the droplets encounter the target. This is used for example for applying an agrochemical on a field. Spraying means are typically mounted on aircraft, tractors, ground rigs, irrigation systems or railcars. A spray may also be dispensed from a canister by mechanical (e.g. pump) or chemical (e.g. propellant) means. A spray composition comprises an aqueous spray medium and the active, dispersed therein, in a solid form or liquid form, optionally in a solution form in an aqueous medium or in a further solvent. Spraying is also used for applying a coating composition onto a surface. This includes, for example, industrial paints, coil-coatings, paper, or film coatings.
In order to improve the deposition of the active ingredient on the target, and thereby in order to improve the efficacy of the spraying, the use of deposition aid agents is known. Deposition aid agents include:
Known drift-control agents include polyacrylamides, polyethylene oxides, and polyvinylpyrrolidone.
Document U.S. Pat. No. 5,824,797 describes using some guar compounds as drift-control agents and as bioefficacy enhancers, in agricultural spray compositions. Document U.S. Pat. No. 6,534,563 describes using some guars as anti-rebound agents in agricultural spray compositions. Compound Jaguar 8000, a hydroxypropyl guar having a molecular substitution of about 0.4 is used as a drift reducer in agricultural spray compositions.
There is a need in providing new spray compositions.
The invention relates to new spray compositions. Thus, the invention relates to a spray composition having an aqueous spray medium, an active ingredient, and a deposition control agent, wherein:
the composition comprises at least one surfactant, and
the deposition control agent is selected from the group consisting of the following:
alkyltrimethylammonium and hydroxyalkyl, preferably hydroxypropyl, groups, the total molecular substitution being preferably of at least 0.1.
The composition presents improved deposition properties in the presence of the surfactant.
The invention also relates to a method of controlling the deposition of a composition comprising an active agent, comprising the step of:
preparing a spray composition according to one of the preceding claims, and
ground or aerial spraying or discharging droplets of the composition.
The improved and/or controlled deposition properties relate to drift-control and/or anti-rebound and/or anti-leaching and/or anti-misting properties.
Definitions
In the present specification, the term “molecular substitution” (“ms”) refers to the number of derivatizing groups per monosaccharide unit of the guar. This is a parameter relating to the derivatizing groups. The molecular substitution can be determined by the Zeisel-GC method, based on the following literature reference: K. L. Hodges, *W. E. Kester, D. L. Wiederrich, and J. A. Grover, “Determination of Alkoxyl Substitution in Cellulose Ethers by Zeisel-Gas Chromatography”, Analytical Chemistry, Vol. 51, No. 13, November 1979. When using this method the following gas chromatograph conditions can be used:
In the present specification, the term “degree of substitution” (“ds”) refers to the number of hydroxyl groups of the guar substituted with the derivatizing groups, per monosaccharide unit of the guar. This is a parameter relating to the derivatized sites.
An example of the definitions of ms and ds is given in the figure
For this hydroxypropyl guar, ms=4/3=1.33 and ds=3/3=1.
In the present specification, the term “molecular weight” of the deposition control agent refers to the weight average molecular weight measured using Gas Permeation Chromatography. This can be measured with the following:
The characteristics of the drop are described using the following parameters:
The “retraction speed” of the drop impacting the surface is defined as the slope of D(t)/D0 as a function of time, taken from the maximum in D(t)/D0, typically at 2 ms in the results presented here, until 10 ms, as shown in
Images are captured using a high speed camera Phantom 5 Science Technology that allows variation in the frame capture rate. This capture rate is varied according to the speed of impact of the drop, typically at 3 m/s impact a frame rate of 1000 frames/sec is used. A 10 ml syringe is filled and connected to a pump; the solution is pushed at 1 to 3 ml/h through silicon tubing equipped with a needle of 0.38 mm OD (gauge 21). This needle generates drops of about 2 mm in diameter.
The drops are projected onto a surface target (Parafilm) from a height of 50 cm which results in an impact speed of the drops of 3 m/s. Parafilm is used as a model surface in order to mimic the waxy cuticle of a leaf surface.
The droplet size is measured from the images captured by the camera by translating the number of pixels into millimeters. This was also confirmed from measurements of the mass of a known number of drops collected and weighed.
Deposition Control Agent
The deposition control agent is a derivatized guar gum having hydroxyalkyl grafts, and optionally other grafts.
Guar gum is the refined endosperm of the legume seed of Cyamopsis tetragonolobus (L.) Taub., a plant which physically resembles the soy plant. The gum is a pure food vegetable colloid recognized by the agricultural, chemical and food formulation industry for many years as having excellent thickening, film-forming and stabilizing properties.
Guar is often used in foods as a thickener and a binder of free water. In salad dressings, guar raises the viscosity of the emulsion and decreases the separation rate. Because guar functions to bind free water, it is used to stabilize foods such as ice cream by inhibiting the formation of ice crystals. Guar is also utilized to stabilize certain delicate, non-food emulsions such as 1:1 mixtures of water and mineral oil.
Guar has been shown to be useful as a lubricant not only by facilitating smooth extrusions at low pressures, but the additions of small amounts of guar have resulted in the reduction of frictional pressure drops in process water lines by up to 50%, thus increasing pump life and capacities and decreasing power requirements.
Functionally, guar is a cold water swelling, nonionic polysaccharide which develops and maintains its properties over a wide pH range. The guar polysaccharide is a complex carbohydrate polymer composed essentially of a straight chain of mannose units with single-membered galactose branches; chemically classified as a polygalactomannan.
Guar solutions or dispersions are simply prepared by rapidly sifting dry gum into a vigorously agitated tank of water and permitting the gum to hydrate. Higher water temperatures can shorten the hydration time so long as the heating is not so prolonged or excessive as to degrade the polymer.
At concentrations used in this invention, it is believed that solutions or dispersions of guar essentially have a zero yield value, i.e., they begin to flow at the slightest shear.
The nature of guar allows almost constant viscosity for a given solution concentration over the pH range of 3-10. Above pH 11, a lower viscosity results from the decreased ability of the gum to hydrate. The optimum hydration range occurs between pH 5 and 8. This unusual compatibility of guar over the 3-10 pH range is attributed to the nonionic nature of the molecule.
Etherification and esterification reactions can be made on the guar hydroxyl functionalities. The C6 hydroxyl position is the most reactive position for etherification, for example, with propylene oxide, but the secondary hydroxyls are also probable sites.
Principle etherification reactions are carboxymethylation via monochloroacetic acid, hydroxyalkylation via ethylene oxide or propylene oxide, and quaternization with various quaternary amine compounds containing reactive epoxide or chloride sites. Anionic and cationic sites modify the way the guar molecule interacts with inorganic salts, hydrated cellulosic and mineral surfaces, and organic particulates.
In general, the hydroxyalkyl ethers of polygalactomannans are prepared by reacting the polygalactomannans with alkylene oxides under basic conditions. In U.S. Pat. Nos. 3,723,408 and 3,723,409, guar flour is reacted with alkylene oxides in the presence of water and sodium hydroxide. The reaction product is then neutralized with acid, washed with an alcohol-water mixture, and is then dried and ground. In U.S. Pat. No. 3,483,121, the polygalactomannans and the alkylene oxides are reacted under basic conditions with small amounts of water and larger amounts of water miscible or water immiscible organic solvents.
Specific hydroxyalkylating agents include ethylene oxide, propylene oxide-1,2; butylene oxide-1,2; hexylene oxide-1,2; ethylene chlorohydrin; propylene chlorohydrin; and epichlorohydrin.
Hydroxypropylation increases the gum's solubility, resulting in a product which hydrates rapidly, regardless of water temperature. Hydroxyalkyl derivatives are more tolerant of the water-miscible solvents and thus can swell in and develop viscosity in aqueous solutions containing low molecular weight organic solvents such as methanol, ethanol, etc. Both hydroxyalkyl and carboxymethyl derivatives typically form clearer solutions than standard guar gum and also hydroxyalkyl derivatives resist thermal degradation better than standard guar. Hydroxypropyl guar is particularly useful as a flow modifier and friction reducing agent which does not flocculate solids.
Carboxyalkyl ethers and mixed carboxyhydroxyallyl ethers of polygalactomannans are described in U.S. Pat. Nos. 3,740,388 and 3,723,409, respectively. These derivatives are made by reacting the polygalactomannan with the derivatizing agents (halofatty acid and alkylene oxide) in a water-alcohol mixture followed by washing with water-alcohol mixtures.
Specific carboxyalkylating agents include chloroacetic acid, chloropropronic acid, and acrylic acid.
Carboxymethylation introduces an anionic function to the polymer chain and further increases the solubility of guar. Carboxymethyl hydroxypropyl guar is exceptional in its ability to suspend undissolved solids.
Other derivatives of polygalactomannans are described in such patents as U.S. Pat. No. 3,498,912 (quaternary ammonium alkyl ethers). In the described processes, the reactions are conducted in water-organic solvent mixtures and the reaction products are washed with solvents of water solvent mixtures.
Grafted guar derivatives may be formed by the use of grafting reactions, and these products may or may not also be derivatized using the methodologies herein described.
Specific quaternary ammonium alkylating agents are such agents as 2,3-epoxypropyl trimethylammonium chloride, 3-chloro-2-hydroxypropyl trimethylammonium chloride and the like.
The term “derivatized guar” is meant to include any of the above described derivatized guar products.
Guar, derived from a nitrogen-fixing, renewable resource, is a versatile, environmentally friendly, highly biodegradable polymer. Derivatized guars are slightly less sensitive to biological degradation, as the molecules are less suitable as food for common organisms.
The deposition control derivatized guar advantageously has a molecular weight of from 50,000 g/mol to 10,000,000 g/mol, preferably of from 200,000 g/mol to 5,000,000 g/mol and more preferably of from 1,000,000 g/mol to 5,000,000 g/mol.
Examples of derivatized guars suitable for the invention include the following:
The amount of deposition control agent in the spray composition is advantageously of from 0.001 to 2% by weight, preferably of from 0.01 to 0.5% by weight, more preferably of from 0.01 to 0.1% by weight. Is it believed that the higher the molecular substitution is, and/or the higher the number of carbon atoms in hydroxyalkyl groups is, the better the anti-rebound effect is, and/or the lower the amount of the derivatized guar is needed.
Thus, the spray composition is advantageously such that the deposition control agent is hydroxypropyl guar having a molecular substitution of at least 0.6, preferably of at least 0.8, more preferably of at least 1.1, and even more preferably of at least 1.3, and the amount thereof is of from 0.001 to 2% by weight, preferably of from 0.01 to 0.5% by weight, more preferably of from 0.01 to 0.1% by weight, or the deposition control agent is hydroxybutyl guar having a molecular substitution of at least 0.15, 0.001 to 1% by weight, preferably of from 0.01 to 0.5% by weight, more preferably of from 0.01 to 0.05% by weight.
Performance
Performance can be measured by comparing the retraction speed of the drops (as defined above), where a polymer giving a lower retraction speed has a lower tendency to rebound. The critical retraction speed for rebound might depend on the characteristics of the impact, including the drop size, impact velocity and additives. By keeping the drop size and impact velocity constant, the effect of the added deposition control agent can be evaluated through comparing the retraction speeds of the drops. A performance of one deposition control agent is thereby compared with another.
The composition, the surfactant, the amount thereof, the deposition control agent, and/or the amount thereof are preferably such that the retraction speed is of lower than 200 mm/s.
Surfactant
The spray composition comprises at least one surfactant. The surfactant usually helps in formulating the active ingredient in the spray composition. However the surfactant might modify the affinity of the composition for the surface of the target, for example a leaf. Without being bound to any theory it is believed that invention is at least partly connected to controlling the affinity modification.
Various surfactants, or combinations of surfactants, can be present in the composition. The surfactants include anionic, nonionic, cationic, amphoteric, and zwitterionic surfactants, and mixtures thereof.
Anionic surfactants that are suitable for the spray composition according to the invention include:
It should be noted that in the case where the compounds are partially or completely in the salt form, the counter-ion can be an alkali metal such as sodium or potassium, or an ammonium ion with formula N(R)4+ where R, which may be identical or different, represents a hydrogen atom or a C1-C4 alkyl radical which may be substituted by an oxygen atom.
Nonionic surfactants that are suitable for the spray composition according to the invention include:
Amphoteric or zwitterionic surfactants that are suitable for suitable for the spray composition according to the invention include:
in which formulae:
The concentration of surfactant present in the spray composition can be of at least twice the critical micellar concentration in water. One skilled in the art knows how to measure the critical micellar concentration. These data are also available in literature, for example in “Industrial Utilization of Surfactants” by Manilal Dahanayake and Milton J. Rosen (AOCS Press).
The spray composition preferably comprises at least 0.01% by weight of surfactant, and preferably less than 5% by weight, more preferably between 0.05% by weight and 2% by weight, wherein these amount relative to the total amount of surfactants in the composition (mixture of surfactants).
Active Ingredient
The active ingredient is preferably an agrochemical active ingredient. By agrochemical active ingredient it is meant a compound having an effect on a plant growth, whether by killing undesired organisms or avoiding development thereof, or by directly having an effect on the plant. The active ingredient can be an herbicide, a pesticide, a fungicide, an aphicide, a miticide, a fertilizing agent or a compound having another action.
Examples of active ingredients include:
The spray compositions comprising agrochemical active can further comprise the following ingredients:
According to other embodiments, the spray composition is:
The composition, advantageously the compositions comprising an agricultural active ingredient, can be ground sprayed, aerial spread or discharged in droplets. This is advantageously performed though a nozzle, and the droplets preferably have a size of at least 50 μm, preferably of at least 150 μm, and of less than 5 mm, preferably of less than 2 mm.
Some details or advantages of the invention will appear in the non-imitative examples below.
The following ingredients were used in the Examples:
The following compositions are prepared (amounts in weight %). C stands for comparative):
Impact Test
The drop impact experiment is carried out as follows. The underside of a strip of parafilm of 6.0 cm×2.5 cm is carefully stuck to a glass plate by wetting the plate with a water spray. Any scratch, compression or contamination of the surface is avoided by keeping the protective layer of the parafilm in place. The protective film on the upper side is then carefully removed just prior to impacting a drop. Fluid is fed to the needle and the formed drop falls under gravity from a height of 50 cm onto the above described surface. The Phantom 5 high-speed camera captures the images of the falling drop and its impact on the surface. The images are then analysed for the drop size and impact speed. The drop impact speed is measured by knowing the number of pixels in the image that corresponds to 1 mm, and knowing the frame capture rate (typically 1000 frame per second).
| Number | Name | Date | Kind |
|---|---|---|---|
| 3483121 | Jordan | Dec 1969 | A |
| 3498912 | Kieper et al. | Mar 1970 | A |
| 3723408 | Nordgren et al. | Mar 1973 | A |
| 3723409 | Yueh | Mar 1973 | A |
| 3740388 | Montgomery et al. | Jun 1973 | A |
| 5824797 | Hazen | Oct 1998 | A |
| 6534563 | Bergeron et al. | Mar 2003 | B1 |
| Number | Date | Country | |
|---|---|---|---|
| 20060105928 A1 | May 2006 | US |
