Biocidal and agrochemical suspensions

Details Biocidal and agrochemical suspensions Biocidal and agrochemical suspensions

1997-05-02

2001-03-13

Levy, Neil S. (Department: 1616)

Drug, bio-affecting and body treating compositions

Preparations characterized by special physical form

Biocides; animal or insect repellents or attractants

C424S405000, C424S408000, C424S409000, C424S490000, 57, C504S116100

Reexamination Certificate

active

06200586

ABSTRACT:

The present invention provides a novel means of suspending relatively water-insoluble biocidal or agrochemical active substances in aqueous media without the need to employ environmentally harmful solvents. The term “agrochemical” is used herein broadly to cover chemicals that kill, entrap, repel or inhibit the growth or reproduction of unwanted organisms (“pests”) or which protect or promote the healthy growth or reproduction of wanted organisms such as crops, ornamental plants, livestock and domestic animals, and which are useful in agriculture, horticulture, forestry, animal husbandry, agriculture, water treatment and land management, e.g. for application to fields, crops, orchards, livestock, gardens, woodland, hedgerows, parks, industrial estates, construction sites, airports, roads, railways, rivers, lakes, ponds, canals, irrigation and drainage works and the like.
Pests include vertebrate vermine such as rodents, rabbits and pigeons, invertebrates such as insects, mites, slugs, snails, nematodes, flatworms, millipedes and pathogenic protozoa, weeds, fungi, moulds, bryophites, lichens, algae, yeasts, bacteria and viruses.
“Biocidal and agrochemical active substances” include substances intended to kill, entrap, repel or to prevent or inhibit the growth or reproduction of any or all of the aforesaid pests. They also include growth promoters such as hormones, auxins, giberellins, nutrients, trace elements for application to soil or crops and biocides for use in water treatment such as boiler water, process water, cooling water, oil field injection water, central heating and air conditioning systems, but excludes animal foodstuffs and veterinary preparations for internal administration.
A number of substantially water insoluble biocidal and agrochemical active substances, are used extensively for controlling pests and/or for promoting the healthy growth of crops and livestock. For this purpose it is usually necessary or preferred to apply them in a fluid and preferably a diluted form. This frequently requires that the active substances be formulated in a stable aqueous based concentrate suitable for dilution with water.
Hitherto the only practical approach to formulating many of the less water soluble agrochemicals has been to dissolve them in an organic water-immiscible solvent usually an aromatic hydrocarbon such as xylene or isophorone and emulsify the resulting organic solution in water. A major disadvantage of this method is that the solvents commonly used are undesirable ecologically and from the stand point of human safety. Only the lack of a practicable alternative means of formulating many agrochemicals has prevented more severe restrictions on the use of such solvents.
Other approaches to the problem of applying some of the less water soluble agrochemicals have included the formulation of wettable powders or dispersible granules, both of which present problems for the user of handling solids and dispensing them in liquid. Attempts have been made to prepare concentrated aqueous suspensions of agrochemicals, but these have generally suffered from poor stability leading to sedimentation on standing, high viscosity leading to difficulties in handling and diluting, and/or high cost due to the use of expensive dispersants and thickeners. We have now found a method of suspending relatively water-insoluble biocides and agrochemicals to form highly concentrated, stable, pourable, aqueous-based suspensions suitable for dilution with water prior to application, which method does not rely on the use of potentiafly harmful solvents. The invention is generally applicable to the preparation of stable suspensions of a wide range of insoluble or sparingly-soluble biocides and agrochemicals, including many that have hitherto only been available in organic solvents, or as wettable powders, or dispersible granules, or as unstable suspensions.
We have discovered that substantially water-insoluble or sparingly soluble biocides and agrochemicals may be suspended in concentrations of 10 to 70% by weight or higher in aqueous structured surfactant systems. The expression “structured surfactant system” refers to aqueous systems in which surfactants form mesophases comprising structures larger than conventional spherical micelles, which interact to confer thixotropic properties on the aqueous medium. The structures may be solid, mesophase or liquid and may be in the form of multi layered spherulites or lamellae discontinuously dispersed or emulsified in the system or forming weak reticular structures or of rods or discs. The size of the structures may typically lie within the range 0.01 to 200 microns, preferably 0.5 to 20 microns. Structured surfactant systems are usually formed by the interaction of surfactants with dissolved electrolyte salts or bases. Such systems are present in some liquid detergents and cleaning compositions and have been described, for instance, in GB-2,123,846 and GB-A-2,153,380.
Use of structured surfactants to suspend agrochemicals offers a number of potential advantages. In many instances the activity and/or selectivity of the active material is increased. The structured surfactants are capable of suspending a wide range of particle sizes and may be adapted to a wide range of pH e.g. by appropriate choice of surfactant. The systems are generally obtainable in a shear stable form which facilitates wet milling.
Our invention provides a suspension comprising an aqueous structured surfactant having suspended therein particles or droplets of a substantially water insoluble or sparingly soluble biocidal or agrochemical active substance in a weight ratio of total surfactant to said active substance of less than 20:1. In particular our invention provides such suspensions which comprise water, sufficient surfactant to be able to provide a solid-suspending structure and sufficient dissolved surfactant-desolubilising electrolyte to form said structure.
Preferably the product may be a lamellar structure such as those described in GB-2 123 846 or most preferably a spherulitic structure such as those described in GB-A-2 153 380.
Surfactants
The compositions of our invention preferably contain at least 3%, more usually at least 4%, e.g. at least 5% by weight of surfactants. The surfactants may constitute up to about 35% by weight of the composition, although we prefer on economic grounds to use lower concentrations e.g. less than 30%, more usually less than 20%, preferably less than 15%, e.g. 7 to 10% by weight.
The surfactant may for example consist substantially of an at least sparingly water-soluble salt of sulphonic or mono esterified sulphuric acids e.g. an alkylbenzene sulphonate, alkyl sulphate, alkyl ether sulphate, olefin sulphonate, alkane sulphonate, alkylphenol sulphate, alkylphenol ether sulphate, alkylethanolamide sulphate, alkylethanolamide ether sulphate, or alpha sulpho fatty acid or its Easters each having at least one alkyl or alkenyl group with from 8 to 22, more usually 10 to 20, aliphatic carbon atoms. Said alkyl or alkenyl groups are preferably straight chain primary groups but may optionally be secondary, or branched chain groups. The expression “ether” hereinbefore refers to oxyalkylene and homo- and mixed polyoxyalkylene groups such as polyoxyethylene, polyoxypropylene, glyceryl and mixed polyoxyethylene-oxypropylene or mixed glyceryl-oxyethylene, glyceryl-oxypropylene groups, or glyceryl-oxyethylene-oxypropylene groups, typically containing from 1 to 20 oxyalkylene groups. For example, the sulphonated or sulphated surfactant may be sodium dodecyl benzene sulphonate, potassium hexadecyl benzene sulphonate, sodium dodecyl dimethyl benzene sulphonate, sodium lauryl sulphate, sodium tallow sulphate, potassium oleyl sulphate, ammonium lauryl monoethoxy sulphate, or monethanolamine cetyl 10 mole ethoxylate sulphate.
Other anionic surfactants useful according to the present invention include fatty alkyl sulphosuccinates, fatty alkyl ether sulphosuccinates, fatty alkyl sulphosuccinamates, fatty alkyl ether sulphosuccinamates, acyl sarcosinates, acyl taurides,

Affiliated with

Also associated with

Rating

Biocidal and agrochemical suspensions does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Biocidal and agrochemical suspensions, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Biocidal and agrochemical suspensions will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2440816