| Stable aqueous suspension concentrate for delivery of uv-labile water-insoluble biocides -> Monitor Keywords |
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Stable aqueous suspension concentrate for delivery of uv-labile water-insoluble biocidesRelated Patent Categories: Drug, Bio-affecting And Body Treating Compositions, Topical Sun Or Radiation Screening, Or Tanning PreparationsStable aqueous suspension concentrate for delivery of uv-labile water-insoluble biocides description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20070224135, Stable aqueous suspension concentrate for delivery of uv-labile water-insoluble biocides. Brief Patent Description - Full Patent Description - Patent Application Claims
BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] This invention relates to delivery systems for water-insoluble active chemicals, and, more particularly, to a stable aqueous suspension concentrate of a UV-labile, water-insoluble biocide active concentrate to stabilize such actives against the degradation effects of sunlight and UV-radiation. [0003] 2. Description of the Prior Art [0004] Numerous delivery systems and formulations have been proposed to provide aqueous dispersions of substantially water-insoluble biocide active chemicals such as iodopropargyl butyl carbamate (IPBC). For example U.S. Pat. No. 6,506,794 describes an aqueous dispersion of halopropargyl compounds and a partially hydrolyzed polyvinyl alcohol. However, such active dispersions are quite susceptible to degradation upon storage and/or exposure to UV-radiation. In particular, the decomposition of IPBC typically results in the formation of a yellow or brown by-product. The compositions thus will be unsuitable for use in certain systems in need of antimicrobial protection particularly white aqueous paints. [0005] Various methods and compositions have been described to stabilize biocidal compositions containing IPBC, for example, using UV absorbers and/or organic epoxides in a liquid vehicle, as shown in U.S. Pat. Nos. 4,276,211; 4,552,885; 5,938,825; 6,059,991 and 6,140,370. U.S. Pat. No. 6,616,740 teaches on the use of various glycol carriers for IPBC stabilization. However, none of these disclosures provide a stable IPBC composition as an aqueous dispersion free from yellowing on exposure to UV-radiation. [0006] U.S. Pat. No. 6,156,803 discloses the use of a partially neutralized alkyl vinyl ether-maleic acid half ester copolymer as a dispersing agent for water-insoluble agriculturally active chemicals. Published U.S. Patent Application US 2004/0024099 A1 describes an aqueous suspension concentrate for water insoluble chemicals comprising a mixture of an anionic polymeric suspension agent and a homo- and/or a co-polymer of a heterocyclic vinyl lactam. [0007] Accordingly, it is an object of this invention to provide a stable, aqueous suspension concentrate of a UV-labile biocide active for delivery of such active in stabilized form into formulations and onto substrates. [0008] A particular object herein is to provide such stable concentrates which experience substantially no degradation or coloration upon storage and/or exposure to sunlight or UV-radiation while retaining its bioactivity. SUMMARY OF THE INVENTION [0009] What is described herein is a stable, aqueous suspension concentrate which includes a solid polymeric dispersant comprising one or more anionic polymeric dispersing agents, optionally a co-dispersant which preferably is a homopolymer and/or a copolymer of a heterocyclic vinyl lactam, preferably in a wt. ratio of 0.1:1 to 1:0.1, respectively, a UV-labile, water-insoluble biocide active and a UV-blocker or UV-absorber to stabilize said active upon storage and/or exposure to sunlight or UV-radiation. [0010] Preferably the stable, aqueous suspension concentrate includes a biocide which is a fungicide or preservative. [0011] Most preferably the biocide is a halopropargyl compound, an isothiazolone, a triazole, a phthalimide, benzimidazol carbamate or tetrachloroisophalonitrile; more particularly, iodopropargyl butyl carbamate (IPBC), benzisothiazolone (BIT), propiconazole, N(trichloromethylthio)pthalimide, methyl benzimidazol-2-yl carbamate or tetrachloroisophalonitrile. [0012] The UV-blocker or absorber suitably is titanium dioxide, zinc oxide, stilbenes, or UV-blocking minerals and mixtures thereof. The UV-absorbers can be esters of aromatic or aliphatic acids with appropriate substituents, aromatic ketones, triazines, which usually are commercially available. [0013] In one embodiment of the invention, the stable, aqueous suspension concentrate includes a co-dispersant which comprises a homopolymer or copolymer of vinyl pyrrolidone, and an anionic dispersing agent which is an ionic derivative of methyl vinyl ether-maleic acid half-ester. [0014] A feature of the invention is that the suspension concentrate exhibits essentially no degradation on storage at 50.degree. C. for 30 days, and substantially no discoloration or yellowing on exposure to sunlight or UV-radiation. [0015] The invention herein further comprises a composition which includes the stable aqueous suspension concentrate, e.g. a paint composition; or a coating composition, construction material like concrete, bricks, asphalt, shingles, metals and the like; or a personal care composition. [0016] Another feature of the invention is the provision of an article which comprises a substrate coated with the suspension concentrate described alone; e.g. an article wherein said substrate is wood. DETAILED DESCRIPTION OF THE INVENTION [0017] The primary dispersant in the present solid polymeric dispersant composition of the invention is an anionic polymeric dispersant such as the sodium salt of alkyl vinyl ether/maleic acid half-ester copolymer (Easy-Sperse.RTM.) (ISP), a lignosulfonate or metal salt thereof, e.g. POLYFON.RTM. or REAX.RTM. (Westvaco); a sulfonated naphthalene/formaldehyde condensate, e.g. MORWET.RTM. (Witco); UFOXANE.RTM. or MARESPERSE.RTM. (Lignotech); an alpha-olefin/maleic acid copolymer, a high molecular weight block copolymer with pigment affinic groups, e.g., DISPERBYCK 190 (BYK Chemie) or a polyacrylate, which is capable of dispersing hydrophobic compounds in water, and mixtures thereof. Desirably the monomer of the anionic polymer contains 1-4 anionic sites per mole of repeat units. [0018] The optional co-dispersant in the composition of the invention is a vinyl lactam which is suitably the homopolymer of vinyl pyrrolidone or vinyl caprolactam either optionally substituted on the ring or in the vinyl group with a lower alkyl (C.sub.1 to C.sub.4 alkyl), or a mixture of these homopolymers. Alternatively, the co-dispersant can be a copolymer of vinyl pyrrolidone and/or vinyl caprolactam, e.g. vinyl pyrrolidone/vinyl caprolactam copolymer, vinyl pyrrolidone/vinyl acetate, vinyl pyrrolidone/acrylic acid, vinyl pyrrolidone/acrylate, vinyl pyrrolidone and butane, or a vinyl pyrrolidone and a C.sub.14-C.sub.24 alpha-olefin. The vinyl lactam co-dispersant generally has a weight average molecular weight of between about 5,000 and about 100,000 consistent with a Fikentscher K-value of from about 10 to about 120. The codispersant can be a clay selected from naturally occurring silicates, atta clay, bentonite, diatomaceous earth, and Montmorillonite. In the solid dispersant mixture, the lactam polymer can coil around and coat at least a portion of an active water-insoluble ingredient thus reducing its surface hydrophobicity while retaining the intrinsic hydrophobic character of the insoluble active component. The lactam coating also can associate with anions of the primary dispersant to provide a composition of improved stability and permit high load active compositions for disparate hydrophobic species which are not otherwise suspendable. The use of the co-dispersant lactam polymer in the invention solid mixture permits the use of a lower concentration of the primary anionic polymeric dispersant component which reduces irritant properties and/or foaming. Also the presence of the lactam polymer in the solid mixture allows the use of several otherwise incompatible anionic polymeric dispersants. [0019] The active component of the invention compositions is a particulate, substantially water-insoluble UV-labile biocide compound, or a hydrophobic compound or mixture of such compounds, and is preferably a biocide such as a halopropargyl compound, a isothiazolone, a triazole, a phthalimide, a benzimidazole carbamate, a tetrachloroisophalonitrile and the like. [0020] Some of these biocide compounds usually exhibit significant degradation upon certain storage conditions and/or exposure to sunlight or UV-radiation accompanied by discoloration when used in such products as in paint, wood or personal care formulations. [0021] By the term "substantially insoluble", it is meant that for all practical purposes, the solubility of the compound in water is insufficient to make the compound practicably usable in a spray-on or dip end use without some modification either to increase its solubility or dispersability in water, so as to increase the compound's bioavailability or avoid the use of excessively large volumes of solvent. Compounds having low water solubility usually include those having a solubility of less than 1 gram per 100 grams of water at room temperature conditions. Continue reading about Stable aqueous suspension concentrate for delivery of uv-labile water-insoluble biocides... 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