Quick drying polymeric coating
View Patent ↗Improved agriculturally useful products are provided, including solid materials such as nitrogenous fertilizers (e.g., urea), together with a polycarboxylated polymer selected from the group consisting of a salts of copolymers containing individual quantities of maleic and itaconic moieties. The polymer composition also includes from about 10-60% by weight of an organic drying agent such as a lower alcohol which enhances the quick drying properties thereof. The compositions may also include an amount of boron, and bimodal vinylic polymer made up of quantities of high and low molecular weight (MW) vinylic polymers such as PVA.
1. A method of treating soil comprising the steps of:
forming a composite comprising an agriculturally useful solid product and an aqueous polymer-containing composition applied to said solid product, said composition having a pH of from about 1-4 and including a substantially water-soluble copolymer containing individual quantities of maleic and itaconic moieties, water, and an organic compound drying agent selected from the group consisting of organic alcohols and ketones,
said composite further including from about 0.5-5% by weight boron as boric acid, and an amount of bimodal polyvinyl alcohol (PVA) having individual high and low molecular weight (MW) fractions, said low molecular weight fraction comprising low MW PVA having a weight averaged molecular weight of from about 13,000-23,000, said high MW PVA having a weight averaged molecular weight of about 145,000 and above, said low MW PVA being present in an amount greater than said high MW PVA;
allowing said drying agent and a substantial part of the water present in the composite to evaporate, so that the composite does not contain said drying agent or water to any substantial degree; and
applying said formed and dried composite to soil.
2. The method of claim 1 , said copolymer containing from about 10-90% maleic moieties, and from about 90-10% itaconic moieties.
3. The method of claim 1 , said copolymer consisting essentially of said maleic and itaconic moieties.
4. The method of claim 1 , said drying agent selected from the group consisting of C1-C4 alcohols.
5. The method of claim 1 , said organic drying agent being present at a level of from about 5-60% by weight.
6. The method of claim 1 , said copolymer being in partial salt form and having at least about 93% itaconic and maleic moieties.
7. The method of claim 1 , said composition comprising from about 20-70% by weight of said copolymer in partial salt form, from about 5-60% by weight methanol, and from about 10-50% by weight water.
8. The method of claim 7 , said copolymer salt being present at a level of from about 30-60% by weight, from about 30-50% by weight methanol, and from about 10-25% by weight water.
9. The method of claim 1 , the ratio of said high MW PVA to said low MW PVA being from about 1:2 to 1:20.
10. The method of claim 9 , said ratio being from about 1:4 to 1:12.
11. The method of claim 1 , said polymer-containing composition comprising:
(1) from about 20-50% by weight of maleic-itaconic copolymer, in the form of a partial salt and having at least about 93% itaconic and maleic moieties therein;
(2) volatile organic solvent present at a level of from about 5-60% by weight;
(3) low MW PVA at a level of from about 0.5-10% by weight;
(4) high MW PVA at a level of from about 0.1-4% by weight;
(5) a ratio of high MW PVA to low MW PVA of from about 1:2 to 1:20;
(6) boric acid at a level of from about 0.5-5% by weight; and
(7) water.
12. The method of claim 11 , wherein:
(1) said maleic-itaconic copolymer consists essentially of maleic and itaconic moieties and is present as a partial calcium salt with carboxylate substitution by calcium at a level of from about 1-35%, and in an amount of from about 35-45% by weight;
(2) said organic solvent comprises methanol and is present at a level of from about 35-50% by weight;
(3) said low MW PVA is present at a level of from about 2-6% by weight and has a weight averaged molecular weight Mw of from about 13,000-23,000;
(4) said high MW PVA is present at a level of from about 0.2-2% by weight and has a weight averaged molecular weight Mw of from about 146,000-186,000;
(5) said ratio is from about 1:4 to 1:12;
(6) said boric acid is present at a level of from about 2-4% by weight; and
(7) water forms the balance of said composition.
13. The method of claim 1 , said solid product being fertilizer.
14. The method of claim 13 , said fertilizer selected from the group consisting of urea, ammonium sulfate, ammonium nitrate, and mixtures thereof in the form of granules or prills.
15. The method of claim 14 , said composition applied to the surface of said fertilizer at a level of from about 0.1-1 gallons of said polymer-containing composition per ton of said solid fertilizer.