Alcohol Soluble Biodegradable Compositions

Abstract

Compositions suitable for use as biodegradable coatings, comprising mixtures of naturally sourced waxes and naturally sourced crosslinkable agents. Compositions may be used to impart water resistance to a substrate, to control the release time of soil nutrients, to reduce environmental damage, and to protect seed or crop damage from high local concentrations of salts. Compositions are preferably prepared as aliphatic alcohol and thereafter may be disposed about an agronomically important substrate core or a fibrous substrate, at temperatures below about 90° C. to impart water resistance or extend the storage time.

Claims

1. A substantially anhydrous aliphatic alcohol solution of a biodegradable coating composition, said coating composition comprising about 15% by weight to about 40% by weight of a naturally occurring wax, said wax selected from at least one member of the group consisting of palm wax, ouricury wax, carnauba wax, jojoba wax, rice bran wax, sunflower wax, berry wax, myrica wax, beeswax, and laurel wax; about 85% by weight to about 60% by weight of a naturally occurring crosslinking agent, the naturally occurring crosslinking agent comprising shellac; and 0% to about 5% by weight of a naturally occurring drying oil.

2. A solid-state biodegradable coating prepared from the composition according to claim 1, wherein the substantially anhydrous aliphatic alcohol solution of the composition is disposed upon an agronomically important substrate, and wherein the alcohol is removed, to provide a water-resistant biodegradable coated substrate.

3. The composition according to claim 1, wherein the naturally occurring crosslinking agent comprises about 80% by weight to about 65% by weight of shellac.

4. The composition according to claim 1 wherein the naturally occurring drying oil is selected from the group consisting of linseed oil, hemp oil, safflower oil, tung oil, and mixtures thereof.

5. The coating composition according to claim 1 wherein composition comprises from about 0.5% by weight to about 3.5% by weight of a naturally occurring drying oil.

6. The solid-state biodegradable water-resistant coating according to claim 2 wherein said agronomically important substrate comprises a granule of fertilizer.

7. The solid-state biodegradable water-resistant coating according to claim 2 wherein said agronomically important substrate comprises a seed.

8. The composition according to claim 2, wherein said agronomically important substrate comprises a pesticide.

9. (canceled)

10. The substantially anhydrous aliphatic alcohol solution of a biodegradable coating composition according to claim 1, wherein the coating composition solution is infused into a bast plant substrate.

11. The composition according to claim 10, wherein the bast stem substrate is dried hemp.

12. The composition according to claim 1, comprising about 25% to about 35% carnauba wax and about 75% to about 65% shellac.

13. A process for preparing the biodegradable composition of claim 1 comprising the steps of: selecting a naturally occurring wax, combining about 15 percent by weight to about 40 percent by weight of said naturally occurring wax with about 85 percent by weight to about 60 percent by weight of shellac to produce about 100 percent of a coating composition, adding the combined wax and shellac coating composition with substantially anhydrous aliphatic alcohol to provide an alcoholic coating mixture; and heating the alcoholic coating mixture at a temperature between about 40° C. to about 90° C. to dissolve the combined coating composition: thereby providing a heated biodegradable coating solution.

14. The process according to claim 13, wherein the anhydrous aliphatic alcohol comprises isopropyl alcohol.

15. The process according to claim 13, further comprising the steps of: cooling the heated biodegradable solution, disposing the heated composition solution onto an agronomically important substrate; and evaporating the aliphatic alcohol solvent to provide a biodegradable water-resistant, substantially encapsulated substrate.

16. (canceled)

17. (canceled)

18. The biodegradable coating according to claim 7, wherein the solid-state coating substantially encapsulates the seed, and wherein the substantial encapsulation postpones the germination of the seed.

19. A process for preparing water resistant nutrient charged fertilizer granules comprising the steps of: a) incorporating plant nutrients into a dried fibrous substrate from an aqueous nutrient solution to provide a nutrient imbibed fibrous substrate, b) drying the imbibed fibrous substrate, c) coating the dried imbibed substrate with a substantially anhydrous aliphatic alcohol solution of a composition comprising from about 25% by weight to about 35% by weight of palm wax and about 65% by weight to about 75 % by weight of shellac; and removing the alcohol from the solution to provide a coated dried nutrient-charged fertilizer granules.

20. The process according to claim 19, wherein the fibrous substrate is hemp hurd.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] FIG. 1 is a plot of uncoated calcium nitrate granules (Ex. 1) and uncoated hemp particles (Ex. 10) that were infused with calcium nitrate tested for electrical conductivity versus time.

[0034] FIG. 2 is a plot of coated calcium nitrate granules, including some of the compositions of the invention, tested electrical conductivity versus time.

SUMMARY OF THE INVENTION

[0035] In a first aspect, the present invention relates to biodegradable water-resistant compositions comprising about 15% to about 50% by weight of a naturally occurring wax and about 85% to about 55% by weight of a naturally occurring crosslinkable agent, wherein the compositions are combined in an aliphatic alcohol to form an alcoholic solution.

[0036] In a second aspect, the present invention relates to biodegradable water-resistant compositions comprising about 15% to about 45% by weight of a naturally occurring wax and about 85% to about 55% by weight of a naturally occurring crosslinkable agent, wherein said compositions are combined in an aliphatic alcohol to form an alcoholic solution, disposed onto an agronomically important substrate, and stripped of alcohol to provide a coated substrate.

[0037] In a third aspect, the invention relates to a biodegradable composition comprising about 15% to about 45% by weight of a naturally occurring wax, wherein the wax is selected from ouricury wax, carnauba wax, candelilla wax, beeswax, palm wax, rice bran wax, sunflower wax, berry wax, cane wax, jojoba wax, soy wax, myrica wax, laurel wax, and mixtures thereof; and about 85% to about 55% by weight a naturally occurring or naturally derived crosslinking agent including at least one member selected from the group consisting of shellac and a plant sourced drying oil.

[0038] In a fourth aspect the invention relates to an aliphatic alcohol solution comprising 15% to about 45% by weight carnauba wax, 85% to about 55% by weight shellac, and 0% by weight to about 10% by weight of a naturally occurring or naturally derived drying oil, said oil selected from the group consisting of linseed oil, hemp oil, walnut oil, and tung oil, and mixtures thereof.

[0039] In a fifth aspect the invention relates to a biodegradable coating prepared from an aliphatic alcohol solution comprising 15% to about 45% by weight of a naturally occurring plant wax, and optionally a second animal wax, 85% to about 55% by weight of a naturally occurring or naturally derived crosslinkable agent, and 0% by weight to about 2% by weight of natural or naturally derived colorant, said colorant suitable for indicating the integrity of a dried solid-state coating of the solution.

[0040] In a sixth aspect the invention relates to biodegradable water-resistant compositions comprising about 15% to about 45% by weight of a naturally occurring wax and about 85% to about 55% by weight of a naturally occurring crosslinking agent, wherein said compositions are combined in an aliphatic alcohol to form an alcoholic solution, and infused into an agronomically important fibrous substrate, and stripped of alcohol.

[0041] In a seventh aspect, the invention includes a method of coating a hygroscopic or heat sensitive substrate particle comprising the steps of selecting a naturally occurring wax and naturally occurring crosslinking agent, combining said naturally occurring wax and said naturally occurring crosslinking agent within a substantially anhydrous aliphatic alcohol solvent at a temperature between about 40° C. to about 90° C., to produce a heated solution, disposing the heated solution onto an agronomically important substrate; and evaporating the aliphatic alcohol solvent to provide a biodegradable water-resistant, substantially encapsulated substrate.

[0042] The biodegradable compositions of the invention may be advantageously applied as an alcoholic solution, to substantially encapsulate one or more agronomically important core materials, thereby providing upon drying, a solid-state or substantially solid-state, water-resistant coating. The use of an alcoholic solution permits the deposit of an inventive composition at temperatures between ambient temperature and the boiling point of an aliphatic alcohol. Coating temperatures are preferably between about 25° C. to about 85° C., such as about 30° C. to about 80° C., or such as about 35° C. to about 75° C.

[0043] The resulting solid-state coating advantageously retards the ingress of environmental moisture, water, bioactive soil components and controls the release of agronomically important core chemicals or seeds. When disposed about one or more agronomically important core chemicals, core granules, or core matrixes, the naturally sourced, biodegradable coatings of the invention retard the ingress of substances outside of the solid coating surface by substantially encapsulating the core substance, whilst permitting controlled diffusion of contents when desired. Such protective coatings serve to extend the shelf life or extend the release of core materials through the coating wall. Retarding water activity helps control the delivery of plant or soil nutrients, pesticides, and delays the activity of coated seeds.

[0044] As a consequence of employing natural products, the compositions of the invention are believed to be environmentally responsible compared systems such as isocyanate polymers of the prior art. The inventor has discovered a process that combines mixtures of natural waxes and natural resins, and that can deliver the mixtures as alcohol solutions, using temperatures well below that of the prior art. The selection of the alcoholic solutions of the instant process permits the compositions of the invention to be disposed upon certain heat sensitive substrates at relatively mild temperatures such as below about 100° C., or such as about 90° C., or such as about 80° C. or such as about 70° C., or such as about 60° C., or such as about 50° C., or such as about 40° C. or such as about ambient temperatures. Thus, the novel formulations of the invention can deliver biodegradable protective coatings to granules, seeds, powders, cellulosic substrates, and other surfaces, without imparting water to a substrate and without the use of the relatively high process temperatures previously associated with molten wax or man-made coatings.

[0045] The biodegradable coatings of the invention may be disposed about a desired substrate granule, or seed by passing the material through a bath of an alcohol-based solution of the compositions, such as anhydrous isopropyl alcohol, and thereafter removing the alcohol to provide a biodegradable coated substrate. It will be understood by those having skill in the art that the coating or substantial encapsulation of agronomic core materials be accomplished in steps, such as successive use of solution baths, conveyer “waterfall” coating, or spraying, with intervals of drying. Drying herein refers to evaporation of a carrier aliphatic alcohol, such as isopropyl alcohol, with or without the assistance of forced air, with or without heating, and with or without reduced atmospheric pressure. In general evaporation of the aliphatic alcohol may be accomplished with rotational agitation of coated granules with the assistance of forced air and an exhaust system.

[0046] The biodegradable coatings of the invention may be disposed about a desired core material, granule, particle, or seed by spraying an alcoholic solution of the coating composition onto the agronomically important core surfaces. Examples of important substrates include fertilizer particles, seed particles, pesticide particles, particles infused with plant nutrients, soil modifiers, bast plant stems, bast plant fiber, bast plant hurd, and mixtures thereof. Optionally, coated granules of the invention may be dusted with a mineral powder such as titanium dioxide or mica to improve particle separation or may optionally be mixed with a colorant to provide a visual indication of coating integrity.

[0047] The biodegradable coatings of the invention may be sprayed onto, or “kiss” coated onto a textile or plant fiber substrate in order to provide water resistance. If desired, multiple application steps may be employed to achieve higher levels of one or more naturally occurring compositions of the invention. As it relates to the process of coating granules, a tumbling motion during the cylinder rotation contributes to mixing and agitation as a substrate and solution are processed for alcohol evaporation. Such rotation assists in delivering a more consistent coating to each granule as well as helping to prevent substrate materials from surface bonding to one another. Those of skill in the art will recognize that drying of coated material may be assisted by either forced air, reduced pressure, mild heat, or a combination of those.

[0048] In some embodiments, the process for applying the compositions of the invention, may include more than one crosslinkable or crosslinking agent. For example, the process may include the use of shellac and a drying oil and may be carried in sequential steps or simultaneous steps. In cases in which a drying oil is employed, a crosslink accelerator may be used, such as a UV lamp, excited oxygen, or cobalt neodeconate, may be incorporated into the composition or evaporation step to assist in curing the selected drying oil.

DETAILED DESCRIPTION OF THE INVENTION

[0049] In certain embodiments, the compositions of the invention include from about 15% to about 45% by weight of one or more naturally occurring waxes. The compositions may include from about 15% to about 40% by weight of a naturally occurring wax, such as about 20% to about 35% by weight of a naturally occurring wax, or such as about 15% by weight of a naturally occurring wax, or such as about 16% by weight, or such as about 18% by weight, or such as about 20% by weight, or such as about 22% by weight, or such as about 24% by weight, or such as about 26% by weight, or such as about 28% by weight, or such as about 30% by weight, or such as about, 32% by weight, or such as about 34%, or such as about 35%, or such as about 37% by weight, or such as about 40% by weight of a naturally occurring wax.

[0050] In certain embodiments, the compositions of the invention include from about 10% to about 45% by weight of one or more natural waxes such as beeswax, palm wax, ouricury wax, or carnauba wax, combined with about 85% to about 55% of shellac, and 0% by weight to about 10% by weight of a natural drying oil. In preferred embodiments, the compositions are combined as anhydrous alcohol solutions.

[0051] In certain embodiments, the compositions of the invention include from about 55% to about 90%, by weight, of a naturally occurring crosslinking agent or resin. The compositions may include from about 57% by weight of a naturally occurring crosslinking agent or resin, such as about 59%, or such as about 60%, or such as about 62%, or such as about 65%, or such as about 66%, or such as about 68%, or such as about 70%, or such as about 72%, or such as about 74%, or such as about 76%, or such as about 78%, or such as about 80%, or such as about 82%, or such as about 84%, or such as about 85% of a naturally occurring crosslinking agent or resin. One particularly useful naturally occurring crosslinking agents is shellac resin.

[0052] In some embodiments, the compositions of the invention include an alcohol solution of a naturally occurring wax, a naturally occurring crosslinking agent, and one of more plant nutrients that are infused into a fibrous substrate to provide a fiber-based fertilizer.

EXAMPLES

[0053] The following examples illustrate some of the specific details of the present invention. Equivalent procedures and compositions within the scope of the invention will understood by those skilled in the art. The following examples examined a method of preparing coated granules of a hygroscopic fertilizer while preserving the integrity of each granule. Alcohol solutions of some possible compositions of the invention, together with comparative examples were disposed onto fertilizer granules, the alcohol was evaporated, and some of the coated and dried granules were evaluated by electrical conductivity.

Example 1

[0054] 200 milliliters of laboratory grade anhydrous isopropyl alcohol supplied by Vaxxen Labs, Inc., Cortland, Ohio, was placed in a clean 250 ml heat resistant beaker and gently heated on a water bath until beginning to boil. The beaker was removed from the water bath and the isopropyl alcohol was permitted to cool until reaching a temperature of about 40° C. to about 75° C. 100 grams of calcium nitrate, obtained from Haifa North America, Altamonte Springs, Florida, was charged into a one-gallon cylinder. The charged cylinder was placed on a two-roll platform with the open end tilted at a relatively shallow angle such as about 30 degrees, then rotation was begun. 50 milliliters of the beaker contents were transferred to the charged cylinder in 10 ml to 20 ml increments until completely added. The counterclockwise rotation imparted a tumbling action so as to reduce agglomeration of particles during evaporation. A forced air fan was directed toward the open end of the rotating cylinder to advance evaporation of the isopropyl alcohol (IPA). Once visibly dry, the contents were removed from the cylinder, labelled, and transferred to ajar for subsequent testing.

Example 2

[0055] 200 milliliters of laboratory grade anhydrous isopropyl alcohol from Vaxxen Labs, Inc. was placed in a 250 ml glass beaker and gently heated on a water bath until beginning to boil. The beaker was immediately removed from the water bath and four grams of Shellac Flakes from Liberon V33 Group, France, were added. The beaker was returned to the water bath and the contents were mechanically stirred until the composition was completely dissolved. The beaker was removed from the water bath and permitted to cool until reaching a temperature of about 55° C. to 75° C. 100 grams of calcium nitrate, was charged into a clean one-gallon cylinder, as described in the previous example and rotation was begun. The warmed beaker contents were sequentially transferred to the cylinder in aliquots of 5 ml to 10 ml until 50 ml of test solution was added. The forced air fan was directed toward the open end of the rotating cylinder to advance evaporation of the isopropyl alcohol (IPA). Once visibly dry, the contents were removed from the cylinder, labelled, and transferred to ajar for testing.

Examples 3- 9

[0056] The general mixing and test solution addition process of Example 2 was repeated to prepare the additional compositions of Table 1. All Examples are similarly rotationally dried with the assistance of a forced air fan. In each case the solvent is isopropyl alcohol, abbreviated as IPA. Carnauba wax flakes were sourced from Better Shea Butter, Cedar Park, Texas. Beeswax was sourced from Stakich Inc., Troy, Michigan. Test compositions including controls are depicted in Table 1.

Example 10

[0057] A coffee mill was used to chop dried hemp stalk and leaves to obtain a uniform particle size, then filtered using a 5 mm sieve screen. 25 grams of the chopped dried hemp was transferred to a 100 ml. beaker. 100 grams of calcium nitrate was placed in a separate beaker containing 100 ml. of deionized water, heated gently using a hot plate with stirring, until completely dissolved. The warmed aqueous solution of calcium nitrate was immediately poured onto the chopped dried hemp. A stirring rod was used incorporate press the hemp beneath the liquid surface so as to improve uptake of calcium nitrate among all particles. The beaker of hemp particles and CaNO.sub.3 solution was transferred to a fruit dehydrator to remove the water.

Example 11 (Coated Hemp)

[0058] The procedure of Example 10 was repeated to provide additional portions of dried chopped hemp, imbibed with 100 g of calcium nitrate. A sample of the charged hemp fiber was transferred to a clean one-gallon cylinder, as described in the previous examples and rotation was begun. 50 ml of the formulation of Example 5 was added in increments in order to coat the charged hemp in a similar manner as with the calcium nitrate granules. Once the IPA had evaporated, the contents were removed from the cylinder, labelled, and transferred to a jar for testing.

TABLE-US-00001 Test Compositions Example Wax grams/(percent) Crosslinking Agent grams/(percent) Calcium Nitrate IPA Volume disposed 1 (control) 0.0 g./ (0%) 0.0 g./ (0%) 100 g. 200 ml. 0 ml. 2 4.0 g./ (100%) Carnauba 0.0 g./ (0%) 100 g. 200 ml. 50 ml. 3 3.0 g./ (75%) Carnauba 1.0 g./ (25%) Shellac 100 g. 200 ml. 50 ml. 4 1.0 g./ (25%) Beeswax 3.0 g. / (75%) Shellac 100 g. 200 ml. 50 ml. 5 1.6 g./ (40%) Carnauba 2.4 g./ (60%) Shellac 100 g. 200 ml. 50 ml. 6 1.2 g./ (30%) Carnauba 2.8 g./ (70%) Shellac 100 g. 200 ml. 50 ml. 7 1.0 g./ (25%) Carnauba 3.0 g. / (75%) Shellac 100 g. 200 ml. 50 ml. 8 0.6 g./ (15%) Carnauba 3.4 g./ (85%) Shellac 100 g. 200 ml. 50 ml. 9 0.0 g./ (0%) Carnauba 4.0 g./ (100%) Shellac 100 g. 200 ml. 50 ml. 10 (control onto fiber) 0.0 g./ (0%) 0.0 g./ (0%) 100 g. 200 ml. 0 ml. 11 1.6 g./ (40%) Carnauba 2.4 g./ (60%) Shellac 100 g. 200 ml. 50 ml.

Testing

[0059] To a clean 250 ml. glass beaker was added 200 ml. of cool tap water and a Teflon stirring bar. The water was taken from a series of large pitchers each kept at 23-24° C. The beaker was place on a magnetic stirrer table and speed adjusted until a mild vortex was observed. A Hanna Instruments, GroLine electrical conductivity test probe was inserted, and the meter was switched on. The meter displays a maximum reading of 4.0 milli-Siemens/centimeter (mS/cm).

[0060] Four one-gram samples of examples selected from Table 1 were carefully weighed and labelled. A stopwatch was zeroed, timing begun as the sample was simultaneous added to the beaker. Electrical conductivity readings were recorded at 15 second intervals until the 90 second mark. Table 2 reports the averages of four tests.

TABLE-US-00002 Electrical Conductivity @ Time Conductivity Readings (mS/Cm) Example 15 Seconds 30 Seconds 45 Seconds 60 Seconds 75 Seconds 90 Seconds 1 1.93 3.0 3.7 4.0 4.0 4.0 2 0.85 1.74 2.43 3.0 3.34 3.53 3 1.0 2.0 2.78 3.1 3.3 3.47 4 0.5 0.69 1.0 1.34 1.58 1.8 5 0.25 0.42 0.55 0.69 0.81 0.93 6 0.3 0.47 0.63 0.77 0.9 1.03 7 0.3 0.49 0.67 0.81 0.96 1.1 8 0.3 0.53 0.69 0.85 1.01 1.17 9 0.41 0.78 1.14 1.55 1.9 2.22 10 1.30 1.57 1.79 1.94 2.06 2.17 11 0.31 0.43 0.56 0.62 0.67 0.73

[0061] While particular embodiments of the present invention have been illustrated and described, it will be recognized by those having skill in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. For example, while the inventive compositions are useful for protecting heat sensitive and hygroscopic nutrient granules such as calcium nitrate, these compositions would be also useful for many granules that are not so water or heat sensitive, such as potassium nitrate, ammonium phosphate, potassium phosphate, NPK fertilizers (such as 8-6-6), naturally based pesticides, and the like. Furthermore, the inventive compositions may be applied to additional natural substrates such as dried seaweed, or hemp shiv imbibed with plant nutrients. It is therefore intended to cover all such changes and modifications that are within the scope of this invention within the appended claims.