MXPA00001367A - Precoated controlled release fertilizers and processes for their preparation - Google Patents

Abstract

A controlled release fertilizer formed from nutrient granules having intermediate or precoat layers of organic oil, such as raw linseed oil, prior to application of a polymeric, encapsulating coat. The precoat may also contain a binding agent, such as a fine clay, and a drier. The new fertilizer composition is made by a process of applying the oil precoat, but not curing it until after the encapsulating coat is applied. The use of the precoat provides more desirable controlled (delayed) release characteristics at a lower weight of the encapsulating coat, particularly for nutrient cores having a relatively large number of surface imperfections or discontinuities.

Description

CONTROLLED RELEASE FERTILIZERS, PRECUBIERTS AND PROCESSES FOR PREPARATION The present invention relates to controlled release fertilizers and processes for their preparation. More particularly, it relates to fertilizer compositions in the form of particles formed from granules (such as NPK granules) having intermediate or precoat layers and encapsulated or external layers applied thereto. It is also related to processes for producing compositions in the form of fertilizer particles which have desirable controlled release characteristics.

BACKGROUND OF THE INVENTION Fertilizers have been used for thousands of years to supply nutrients in culture media. It has been known for some time that the benefit provided by the additional nutrients may depend on when it is added to the culture medium and, in turn, be available to the plants in the culture medium. The sudden supply of a lot of fertilizer can be debilitating or even harmful to plants. On the contrary, the REF .: 32768 supply of very little fertilizer or the delay of its supply, can kill of starvation to the plants. It is desirable to provide compositions in the form of fertilizer particles that provide a relatively uniform nutrient level to the culture medium over time or with some other release pattern.

The supply of the correct amount of nutrient during a long period of cultivation requires previously multiple applications of a relatively small amount of fertilizer compositions, a very intense method of work. According to this, controlled release fertilizers have been developed. Normally, it is desirable to apply the fertilizer once every few weeks to a few months.

Generally, controlled release fertilizers have used coverages on the nutrient granules to act as a physical or guímica barrier between the center of the nutrient and the environment of the culture medium. The barrier delays the contact of the center of the nutrient with moisture and therefore delays the dissolution of the center by moisture. The rate of release of the nutrient has depended on the material used as a barrier, and its thickness and integrity, among other factors.

A proposal for the use of barriers or encapsulation techniques is shown in U.S. Patent No. 3,223,518 published on December 14, 1965 by Louis I. Hansen and assigned to Archer-Daniels Midland. The Hansen patent contemplates fertilizer products that have single or multiple layers such as an initial coating applied on the nutrient center and with single or multiple encapsulation layers. As described in the Hansen patent, the initial layer was completely cured before the application of the encapsulation layer. The resulting fertilizer showed delayed release of the nutrient center compared to a nutrient granule without any coverage. However, it has been found that the repeated application of layers and their curing, consumes, time and is not commercially feasible. In addition, the fertilizers prepared according to Hansen, which have only a first initial layer and a single layer of encapsulation, have been described by Hansen with a release of 30-40% of the nutrients in 6 hours of contact with the humidity and 50-60% in 24 hours. This product supplies too much nutrient very quickly to make it acceptable for some application as a controlled release fertilizer.

A further proposal which attempts to provide an encapsulation layer with desirable release characteristics is described in U.S. Patent No. 4,657, 576 published April 14, 1987 by Johannes M. H. Lambie and assigned to Sierra Chemical Company. The center is encapsulated with a water-insoluble resin based on dicyclopentadiene, such that it is sold in the market by the Scotts company in association with the trademark OSMOCOTE. Although the use of a polymer barrier is similar to the encapsulation coverage described by Hansen in reference * 518, ingredients that regulate the pH of the coating have been added. According to this, reference, this improved some aspects of the release pattern.

A recognized deficiency in the application of the polymer barrier, such as the OSMOCOTE encapsulation layer, to the center of a nutrient was that the release properties of the fertilizer depended on the quality of the center or substrate on which the polymer was applied. Discontinuity at the surface of substrates, such as holes in aggregate substrates, deformed granules, or fractured particles, cracks or irregularities, creates an incomplete or non-uniform coverage of the layer. Typically for low coverages in weight, such as 5 parts per cent of center weight ("PPH") / sufficient encapsulation material is not provided to adequately cover defects in the center surface of the granules with low quality center and an unacceptable amount of covered particles is created. imperfect way In predictable form, many of the particles in a fertilizer composition release a lot of nutrients in the first few days, making them unsuitable for some controlled release products (delayed release).

It has been found that attempts to compensate for the non-uniform incomplete coverage of inexpensive and low quality irregular granular centers by applying thicker layers of encapsulation coverage, produce less than desirable results. By doubling the weight of the coverage to 10 parts per hundred, for example, it will cover more efficiently the surface defects in most granules. However, this thick outer coating seals the nutrient so efficiently in many of the granules that it causes a "confinement" or prevents the release of the nutrient from the center into the culture medium for a long period of coverage to be commercially acceptable.

BRIEF DESCRIPTION OF THE INVENTION It is, therefore, a main object of the invention to provide a fertilizer in which the nutrient center possesses a preliminary or intermediate coverage to improve the encapsulation by means of external coverages.

Another object of the invention is to provide a fertilizer in which desirable release characteristics are obtained, particularly for nutrient centers with a high degree of surface imperfections.

An additional and related significant objective is to provide a fertilizer in which the granules of the nutrient plants have multilayer coatings which are cured after application to the center to allow for controlled and desirable release patterns that could not otherwise be obtained with or without the use of higher coverage weights.

Another important objective is to provide a fertilizer in which the surface imperfections of the nutrient granules are covered and / or filled with the use of relatively low coverage weights of the encapsulation layer to avoid thick layers which are expensive and cause blockage of release or a time of excessive induction to allow release.

Yet another significant objective is to provide a process to develop a fertilizer that has one or more of the objectives described above, or other objectives that will be evident in the form of safety and cost efficiency.

In a preferred aspect of the present invention, it has been found that one or more of the above identified, and others, objectives can be achieved using uncured raw linseed oil or other suitable unhealed oil cover between the nutrient center and a non-healing layer. encapsulated granules of nutrient fertilizer such as linseed-dicyclopentadiene oil. The raw flaxseed oil can be mixed with a binding agent such as fine clay, diatomaceous earths or similar materials before its application to the nutrient center. If desired, the processing time of the preparation of the fertilizer composition can be reduced by the additional inclusion of a drying agent such as a manganese / cobalt drying agent together with the oil and the clay mixture.

It has been found that the use of clay with flaxseed oil improves the process for the production of granular fertilizer products with coverage. For example, without the clay a large amount of fines is produced, that is to say small broken pieces of the cover, by the erosion action that the particles suffer during the processing. Likewise, linseed oil alone tends to penetrate the linseed oil-dicyclopentadiene encapsulation coating, bleeding or migrating through the outer encapsulated polymeric layer. The presence of oil on the outside of this layer creates processing problems.

The attempt to solidify the precoverage of flaxseed oil by curing the precoat to create a separate cured layer, as suggested in the Hansen patent 518, prevents undue diffusion or migration of linseed oil into the outer encapsulation layer. In fact, the curing of the precoverage seems to interfere with the physical interaction of the precoverage of crude linseed oil and the encapsulation coverage. It has now been discovered that the presence of uncured raw linseed oil coverage contributes to a significant improvement of the surface defects of the granular nutrient, for the subsequent encapsulation layer for the release properties of the fertilizer composition.

The present invention takes advantage of the previously unknown interaction between non-solid free-motion linseed oil, which can be mixed with a binding agent such as clay, diatomaceous earths and the like, and encapsulation coverage. The interaction provides release characteristics for the finished fertilizer product that could otherwise only be obtained with higher coverage weights, particularly for substrates containing holes or other surface discontinuity or imperfections. Even without fully understanding, it is believed that the interaction of flaxseed oil and the polymeric layer fills and covers more efficiently the surface holes, cracks and crevices of the central granule. This same interaction reduces the induction time.

When compared with previous processing methods in which precoating was applied and then cured before the outer polymeric coating was applied, the novel discovered interaction of oil precoat and polymer encapsulation can be exploited by a new manufacturing process. The precoverage is not exposed to curing temperatures until after the encapsulation coverage is applied, providing an opportunity for the interaction of filling and plugging to occur. If the precoat materials are curable by the temperatures normally used to cure the encapsulation shell, it is expected that the precoat will be cured simultaneously by being exposed to temperatures that cure the encapsulation layer.

The use of the invention allows low quality nutrient granules, with a lower weight of encapsulation coverage, to achieve totally more desirable release characteristics. The present invention is a step forward in the effort to obtain improved coverages of a center that has imperfect surface characteristics without the detrimental effects and large expenses when using higher coverage weights.

BRIEF DESCRIPTION OF THE DRAWINGS.

Figure '1 is a graph of an integral release (as percent of total nitrogen) of nutrient (nitrogen) against time (in hours) for nutrient granules - which have a relatively low sphericity that have been covered by 6 PPH of a polymer encapsulation layer; Figure 2 is a graph of an integral release (as percent of total nitrogen) of nutrient (nitrogen) against time (in hours) for nutrient granules having a relatively low sphericity that have been covered with 8 PPH of a layer encapsulated polymer; Figure 3 is a graph of an integral release (as a percent of total nitrogen) of nutrient (nitrogen) against time (in hours) for nutrient granules that have a relatively low sphericity that have been covered with 10 PPH of a layer encapsulated polymer; Figure 4 is a graph of a total release (as percent of total nitrogen) of nutrient (nitrogen) against time (in hours) for nutrient granules that have a relatively low sphericity that have been covered with a precoverage B (1.0 PPH of a precoverage based on linseed oil) and 6 PPH of a polymer encapsulation layer; Figure 5 is a graph of an integral release (as percent of total nitrogen) of nutrient (nitrogen) - against time (in hours) for nutrient granules that have a relatively low sphericity that have been covered with a precoverage B (1.0 PPH of a precoverage based on linseed oil) and 8 PPH of a polymer encapsulation layer; Figure 6 is a graph of an integral release (as percent of total nitrogen) of nutrient (nitrogen) versus time (in hours) for nutrient granules having a relatively low sphericity that have been covered with a precoverage B (1.0 PPH of a precoverage based on linseed oil) and 10 PPH of a polymer encapsulation layer; Figure 7 is a graph of a total release (as percent of total nitrogen) of nutrient (nitrogen) against time (in hours) for nutrient granules having a relatively low sphericity that have been covered with a precoverage C (0.5 PPH of a precoverage based on linseed oil) and 6 PPH of a polymer encapsulation layer; Figure 8 is a graph of an integral release (as a percent of total nitrogen) of nutrient (nitrogen) against time (in hours) for nutrient granules having a relatively low sphericity that have been covered with a precoverage C (0.5 PPH of a precoverage based on linseed oil) and .8 PPH of a polymer layer of encapsulated; Figure 9 is a graph of an integral release (as percent of total nitrogen) of nutrient (nitrogen) against time (in hours) for nutrient granules having a relatively low sphericity that have been covered with a precoverage C (0.5 PPH of a precoverage based on linseed oil) and 10 PPH of a polymer encapsulation layer; Figure 10 is a graph of a full release (as percent of total nitrogen) of nutrient (nitrogen) against time (in hours) for the Norsk substrate (screening +6, with a sphericity of 80%) covered with 6 PPH of a polymer encapsulation layer; Y Figure 11 is a graph of a complete release (as a percent of total nitrogen) of nutrient (nitrogen) against time (in hours) for the Norsk substrate (screening +6, with a sphericity of 80%) with precoverage C (0.5 PPH precoat based on linseed oil) and 5.5 PPH of a polymer encapsulation layer; DETAILED DESCRIPTION OF THE INVENTION The invention contemplates both a new fertilizer product and a new process for making said product. Generally, the fertilizer particles are made with a nutrient center, a precoverage and an external encapsulation cover. The center may be standard NPK or fertilizer granules that are well known in the art and which are commercially available from Norsk Hydro, Kemira and other companies. Alternatively, the centers of other common nutrients (for example, urea) can also be used. In addition, the center may include one or more secondary nutrients such as calcium, magnesium and sulfur or micronutrients such as iron, copper, zinc, manganese, boron and molybdenum.

While the invention can work with relatively spherical granules with relatively smooth surfaces, the use of the invention makes its greatest impact when producing controlled release fertilizers from granules with irregular shapes or those with surfaces that have holes, imperfections, fractures and cracks. An example of the relatively smooth nutrient center may be NPK complex fertilizers from Norsk. Nutrient granules with a large number of discontinuous surface imperfections tend to be. less expensive, they are commercially. available, and generally have a relative sphericity of 50% or less. Therefore, in a preferred aspect of this invention, low sphericity materials can be used for the nutrient center.

The sphericity test used here for the purposes of determining the sphericity of the product of the raw material particles is similar to that described by Carpenter and Deitz (Research Article 2238, 3. Res. Of the NBS 41 (37), September 1951). In particular, the sphericity test used here for the purposes of determining the sphericity of the product and the raw material particles use an apparatus consisting of a rotating table 18"in diameter, mounted at an angle of 10 degrees with respect to The rotary table rotates at 2 RPM The particles are fed from a vibrating feeder The particles are fed to the lower left side of the rotating table, approximately 5 inches from the center, 45 degrees from the perpendicular. The particle drop is preferably 1/4 inch or less.

Approximately 100 g of nutrient particles are fed slowly into the turntable. The spherical particles roll off the turntable into a collecting tray. The non-spherical particles remain on the turntable to the point where they are physically removed. Then, the two fractions are weighed to determine the percent sphericity.

The precoating layer is preferably a mixture of a crude linseed oil and a fine clay oil. The precookings must be able to flow over the surface of the substrate and penetrate into the outer covering. They must have a low surface energy and low viscosity. The acceptable alternatives to flaxseed oil are other organic oils such as soybean oil, tung oil, drying oils modified with dicyclopentadiene and lubricating oils. Other oils with viscosities of less than 500 CPS which are compatible with the external coatings can also be used if they possess sufficient low surface energy, are compatible with the material used such as the encapsulation layer, and are capable of adequately penetrating the encapsulation layer, having therefore impact on the release characteristics. The precoverage can also be a linseed oil and dicyclopentadiene resin. This resin, normally used as an encapsulation coating with mineral spirits at a concentration greater than 50% solids, can be applied as a precoat with a different dilution with mineral spirits of 40% resin solids. Preferably, the binder mixed with the organic oil is a fine clay. Fine clays are commercially available as RM-4 from Industrias Minerals Company, and Huber 90 and Polygloss 90, both from JM Huber Corporation. Alternatively, instead of fine clay, or in addition to, talcs, diatomaceous earths, and adsorbent silica may be used.

Precookings such as raw linseed oil tend to flow through the outer layer, making it soft and susceptible to abrasion. The use of clay in a mixture of linseed oil and clay restricts the movement of linseed oil to only the portion of the outer layer adjacent to the precoat. Such clays typically have an oil absorption of 40% or greater, with a particle size with a minimum of 60%, which passes through a 200 mesh. It has been found that good coverages have been obtained with precookings such as oil of raw flaxseed, however when flaxseed oil is used, additional processing time has been required to dry the outer covering. The problem was solved by mixing a dryer with the oil-clay precooking. Examples of suitable dryers are cobalt manganese, manganese, cobalt calcium, zirconium cobalt and their mixtures.

The precoverage is preferably applied at a rate of 0.5-1.0 PPH of the weight of the center. Alternatively, pre-coverage may contain up to 3.0 PPH of oil. The greater proportion of oil in the precoverage is particularly useful to obtain desirable release characteristics for nutrient centers with sphericities as low as 20%.

The outdoor coverage must be compatible with pre-coverage and provide the necessary coverage and barrier characteristics. The outer covering is preferably a dicyclopentadiene polymer product ("DCPD", which contains either flaxseed oil or an alkyd resin based on a soybean oil) such as the OSMOCOTE resin commercially available from The Scotts Company. Anatively, other sealing materials may be used as encapsulation coatings such as oleoresin drying oils, other thermosetting polymers and resins such as polyesters, polyamides or polyurethanes, and thermoplastic resins. More specific examples are flaxseed oil modified with DCPD or alkyd resins, and hydrocarbon thermoplastic resins.

The desirable beneficial release characteristics of the fertilizer compositions of the present invention can be achieved by exposing the precoating materials at such high temperatures that they cure the oil after it is applied to the nutrient, but when the encapsulation layer is applied. In the preferred aspect, in which the curing temperature for linseed oil is similar to that of the polymeric encapsulation layer, the precoating layer can be simultaneously cured with the encapsulating material, in situ, after application of the encapsulated layer to the nutrient granule. Anatively, it may be possible to cure the precoat after the encapsulation layer is applied, but before the encapsulation layer is cured.

The precoverage of flaxseed oil of the preferred aspect can be applied at temperatures as high as 140 ° C without carrying out a significant cure. The encapsulation coverage is expected to be applied at 140 ° F or more. Because flaxseed oil takes longer to cure than the encapsulated polymer in the preferred aspect, the curing of the oil and the encapsulation layer must occur at the same time.

Example 1 A batch of 40 Ib of a granular nutrient substrate (center) is placed in the pilot applicator device of the cover and preheated to 130-140 ° F for 15 minutes before coverage. The precookings are added at a speed of approximately 0.1 Ib. / min. 130-140"F. Immediately after the precoverage was added, the application of the encapsulation coverage was started at approximately 0.1 Ib per minute and the bed temperature gradually increased, and from time to time, two three-minute stops include during the coverage of the polymeric encapsulation to ensure the curing of the initial layers of the encapsulation.The final temperature of the bed was 185-190 ° C. At the end of the liquid addition, the incoming air is cut off, 50 ml of clay are added , the air intake is re-started and the temperature is allowed to cool to 160 ° F. The product is then cooled to 130 ° F in a cement mixer.

The products produced by the previous process were analyzed according to the DDR-40 test. For the DDR-40 test, the samples were placed in water at 40 ° C. An amount of 15 g. of product in a nylon bag are suspended in 150 g. of H20. Test aliquots were removed and a total change of water is made at 1, 3, 7 and 10 days and then intervals of 3 or 4 days until the volume of nutrients has been released. An aliquot of water is analyzed at each test interval. to determine nitrogen (sometimes also potassium and phosphorus and other nutrients) and are reported as nitrogen release in percent of the total nitrogen in the product.

Table 1 For certain controlled release products, an incremental release in the 32-day DDR, as shown for the uncovered fertilizer composition, is undesirably long. For such products, an acceptable 13% or less of imperfectly covered particles released in the first 3 days, as reflected in DDR-40 results 3 days of release.

In Table 1, the results of the DDR of the fertilizer composition of pilot plant 1, without coverage, can be compared with the composition of pilot plant No. 2 that contains precoverage. Note the improvement in. the release reported for DDR-40 3 days, from 16% to 10% with the precoverage of flaxseed oil. Also, the precoverage composition showed a peak release on day 14 compared to 32 days without precoverage. A similar improvement is shown in the production plants for DDR-40 for the comparison of compositions without a precoverage when compared with compositions that have a pre-coating of linseed-clay oil.

Example 2 The three precoat compositions illustrating forms of use of the present invention are shown in Table 2 below.

Table 2 The Precoat A resin is a low viscosity solution of a DCPD-modified linseed oil after dilution with mineral spirits, and mixed with an appropriate absorbent and drying agent. The precoverage has been diluted with mineral spirits so it contains around 40% resin solids. Precookings B and C represent 1.0 PPH and 0.5 PPH, respectively, of crude linseed oil with an appropriate adsorbent and drying agent. The analysis of the dissolution rate of the pre-coated products was done by means of ART-80 (water slurry at 80 ° C) conducted in a manner similar to the DDR-40 method of Example 1, except that there is no water change as is described above for the DDR-40 test. For some controlled release products, a maximum ART-80 release of 15 hours or less is generally acceptable, and a maximum ART-80 release of about 10 hours is desirable. A crude granular substrate (17-10-13) having a relatively large number of surface imperfections (sphericity of 50% or less) was used. Three weights of encapsulation coverage, 6, 8 and 10 PPH were used for each precoverage. The desirable release rate ART-80 produced patterns in which only 4% or less of the nutrient was released after two hours (when using particles, with imperfect coverage): The incremental speeds for a standard fertilizer in which no precoverage was used is shown in Figures 1-3. The release rates accumulated in two hours are the sum of the incremental velocity at hour one plus the incremental velocity at hour two. A high rate of release accumulated in two hours usually indicates many particles with imperfect coverage. Figure 1 shows the incremental velocity for the case of 5 PPH that has a relatively thin layer of OSMOCOTE material. It has been found that this fertilizer composition has an accumulated release rate of 17% at two hours, an unacceptably high result. This suggests that the encapsulation coverage does not sufficiently cover the surface imperfections in many of the granules. The case of 8 PPH, shown in Figure 2, also has an accumulated velocity above the specification of 4% at two hours. Finally for 10 PPH, shown in Figure 3, the product is below 4% at two hours for particles with imperfect coverage.

Figures 4-6 show the release results ART-80 using precoverage B, 1 PPH with a 3: 1 ratio of linseed oil and more drying clay. By using the precoverage B and 6 PPH of the encapsulation coverage, the ART-80 two-hour release is reduced to around 5% (Figure 4). The release for the coverage of 8 PPH, the case of the Precoverage B (Figure 5), is similar to that of the heavier coverage, 10 PPH, the case without precoverage (Figure 3), and shows improvements in the release ART- 80 two hours on the granules e? . which was used the 8 PPH of material OSMOCOTE without precoverage (Figure 2). By increasing the amount of encapsulation coverage, the maximum peak moves towards longer times to provide product longevity series (Figures 4-6). The Precoverage B with 6 PPH of resin reaches the maximum release in about 10 hours as is normally the case for some controlled release products.

• Figures 7-9 show the results for compositions in which the encapsulated layers with 6, 8 and 10 PPH covered the Precoverage C (0.5 PPH of linseed oil with clay (ratio 3: 1) and drying). The Precoverage C gives an intermediate result between the case without precoverage and with 1 PPH of precoverage. With 8 PPH (shown in Figure 8), the Precoverage C shows a reduction in the number of particles with imperfect coverage when compared with 8 PPH without precoverage (Figure 2).

Similar benefits were obtained with Norsk substrates having relatively smooth surfaces. Due to the smooth surface of the Norsk aggregates, the amount of flaxseed oil used in the cover was reduced to 0.5 PPH (Precoverage C). ART-80 data (release in hours at 80 ° C) are used for comparison purposes. Figures 10 and 11 show the incremental release rates for the Norsk substrate.

The use of the +6 mesh fraction (large particles) results in a relatively large amount of irregularly shaped aggregates giving enough particles with imperfect coverage and a very long induction period. The sphericity of the +6 mesh fraction is 80%. Note that the '6 PPH encapsulation layer standard on this substrate gives 9% cumulative release in two hours (a maximum of 4% is desirable) and produces a peak release in about 20 hours. This suggests a large residual material with unacceptable amounts of imperfectly coated particles. When using Precoverage C followed by 5.5 PPH of encapsulation layer (Figure 11), the percentage of imperfectly covered particles is reduced to close to less than 5% in two hours, and peak-release occurs around 13 hours .

The precoverage of the present invention allows to achieve several benefits: 1) Rapid release products can be produced without increasing the particle fraction with imperfect coverage even when a center of inexpensive material is used. This allows the production of more efficient controlled release products. 2) Reduced levels of coverage (less expensive products can be made with quantities as small as 5 PPH of resin and Precoverage B). 3) Reduction of the period (minimum release rate) of induction (inactive) that was demonstrated, for example, without the use of flaxseed oil (see Table 1 and Figures "10-11) • ' Although the invention has been described in its preferred forms with some degree of particularity, it should be understood that the present description has been made by way of example only. Numerous changes can be evidenced in the details of the compositions and in the operational stages of the method and of the materials used - without departing from the spirit and scope of the invention.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention Having described the invention as above, the content of the following is claimed as property.

Claims (33)

1. A controlled release fertilizer, characterized in that it comprises: - a granular center of nutrient material; - a preliminary coverage of an organic oil applied to the granular center; and - a coating of polymer encapsulation applied on the cover. preliminary on the granular center without the organic oil being cured; - the preliminary coverage being cured after the application of the polymeric encapsulation coverage.
2. The controlled-release fertilizer of claim 1, characterized in that the organic oil is mixed with a binder selected from the group consisting of clays, talcs, diatomaceous earths, sorbent silicas, and mixtures thereof.
3. The controlled release fertilizer of claim 1, characterized in that the granular center has a sphericity of 50% or less.
4. The controlled release fertilizer of claim 3, characterized in that the organic oil is crude linseed oil.
5. The controlled release fertilizer of claim 1, characterized in that the binder is a fine clay.
6. The controlled release fertilizer of claim 2, characterized in that the preliminary cover additionally includes a blotter.
7. The controlled release fertilizer of claim 6, characterized in that the secant is selected from the group consisting of cobalt manganese, manganese, cobalt calcium, zirconium cobalt, and mixtures thereof.
8. The controlled release fertilizer of claim 1, characterized in that the center is selected from the group consisting of NPK granules, fertilizer granules, urea granules, and mixtures thereof.
9. The controlled release fertilizer of claim 8, characterized in that the center additionally contains one or more secondary nutrients and micronutrients selected from the group consisting of calcium, sulfur, magnesium, iron, copper, zinc, manganese and molybdenum.
10. . The controlled release fertilizer of claim 1, characterized in that the center has a sphericity of 50% or less and the controlled release fertilizer exhibits 4% or less of cumulative release in two hours in the ART-80 laboratory test when the Encapsulation coverage is 8 parts per hundred of center weight or less.
11. . The controlled release fertilizer of claim 10, characterized in that the maximum incremental rate of the ART-80 laboratory test is 15 hours or less.
12. . A controlled release fertilizer, characterized in that it comprises:. - a granular center of nutrient material; - a preliminary coverage on the granular center of a mixture of (a) an oil selected from the group consisting of linseed oil, soybean oil, tung oil, drying oils modified with dicyclopentadiene [, lubricating oils] and mixtures thereof and ( b) a binder agent selected from the group. which consists of fine clays, talcs, diatomaceous earths, absorbent silica, and their mixtures; and, a layer of polymeric encapsulation applied on the cover; the mixture of the preliminary coverage being uncured; and the preliminary coverage being cured after the application of the polymeric encapsulation layer on the covered granular center.
13. . The controlled release fertilizer of claim 12, characterized in that the polymeric encapsulation coating is a dicyclopentadiene copolymer and a composition selected from the group consisting of linseed oil, an alkyd resin based on a soybean oil, and mixtures thereof.
14. . The controlled release fertilizer of claim 12, characterized in that the center has a sphericity of 50% or less and the controlled release fertilizer exhibits 4% or less of cumulative release in two hours in the ART-80 laboratory test when the Encapsulation coverage is 8 parts per hundred of center weight or less.
15. . A controlled release fertilizer comprising a nutrient center, a cover of an organic oil and a polymeric encapsulation layer characterized in that it is produced by a process comprising the steps of: a) application of an organic oil on the nutrient center, without the organic oil is cured; b) application of a polymeric layer on the organic oil before the organic oil is cured; and c) simultaneous curing of the organic oil and the polymeric layer.
16. . The controlled release fertilizer of claim 15, characterized in that the organic oil is applied at about 140 ° F or less.
17. . The controlled release fertilizer of claim 16, characterized in that the simultaneous curing occurs at about 140 ° F or more.
18. . The controlled release fertilizer of claim 15, characterized in that the organic oil is mixed with a binder selected from the group consisting of fine clay, talc, diatomaceous earths, sorbent silica, and mixtures thereof.
19. . The controlled release fertilizer of claim 19, characterized in that the organic oil is additionally mixed with a drier selected from the group consisting of cobalt manganese, manganese, cobalt calcium, zirconium cobalt, and mixtures thereof.
20. The controlled release fertilizer of claim 18, characterized in that the organic oil is crude linseed oil.
21. The controlled release fertilizer of claim 20, characterized in that the binder is a fine clay.
22. . The controlled release fertilizer of claim 21, characterized in that the polymeric encapsulation coating is selected from the group consisting of oleoresin drying oils, polyesters, polyamides, polyurethanes, thermoplastic resins, linseed oil modified with dicyclopentadiene, alkyd resins modified with dicyclopentadiene, hydrocarbon thermoplastic resins, and their mixtures.
23. . The controlled release fertilizer of claim 22, characterized in that the center has a sphericity of 50% or less and the controlled release fertilizer exhibits a cumulative release of 4% or less in two hours in the ART-80 laboratory test when the Encapsulation coverage is 8 parts per hundred of center weight or less.
24. A controlled release fertilizer containing a nutrient center, a precoverage of flaxseed oil, a binder and drying agent, and a polymeric encapsulation layer including dicyclopentadiene, the fertilizer being produced through the stages of: a) coverage of the center with precoverage at about 140 ° F or less, the linseed oil being red. b) encapsulation of the precoat with a polymeric layer; and c) simultaneous curing of the precoat and the polymer encapsulation layer at about 140 ° F or more.
25. . The controlled release fertilizer of claim 24, characterized in that the center has a sphericity of 50% or less and the controlled release fertilizer exhibits a cumulative release of 4% or less in two hours in the ART-80 laboratory test when the Encapsulation coverage is 8 parts per hundred of center weight or less.
26. . A process for making a controlled release fertilizer that uses a nutrient center, characterizes because it consists of the steps of: = 0 coating the nutrient core -on oil, the oil being selected from the group consisting of linseed oil, soybean oil, tung oil, modified drying oils. with dicyclopentadiene and their mixtures. b) application of a layer of encapsulation of polymeric material on the precoverage of the nutrient center; the polymeric layer being applied before the precoverage is cured and the oil is red; and c) curing the precoverage after the application of the encapsulation layer.
27. . The process of claim 26, characterized in that the precoating mixture further comprises a binder selected from the group consisting of fine clay, talc, diatomaceous earths, sorbent silica, and mixtures thereof, and a siccant selected from the group consisting of cobalt manganese, manganese, cobalt calcium, cobalt zirconium, and their mixtures.
28. 28. The process of claim 26, characterized in that the precoverage and encapsulation coverage are cured simultaneously.
29. 29. The process of claim 26, characterized in that the precoat is exposed to temperatures of 140 ° F or less before the application of the encapsulation layer.
30. 30. The process of claim 29, characterized in that the curing is carried out by exposure to a temperature of about 140 ° F or more.
31. 31. The process of claim 27, characterized in that the precoverage is applied in the range of 0.5 to 3.0 parts per hundred of the weight of the nutrient center.
32. 32. The process of claim 26, characterized in that the encapsulation layer is applied in the range of five to 10 parts per hundred of the weight of the nutrient center.
33. 33. The process of claim 26, characterized in that the center has a sphericity of 50% or less and the controlled release fertilizer exhibits 4% or less of cumulative release in two hours in the ART-80 laboratory test when the encapsulation coverage it is 8 parts per hundred of the weight of the center or less. . A process for making a controlled release fertilizer that uses a nutrient center, which has surface discontinuities, characterized the process because it consists of the steps of: a) coating the nutrient core with a mixture of crude linseed oil, a binding agent and a drying, applying the precoverage in a proportion of about 0.5-3.0 parts per hundred of the weight of the center and being exposed to temperatures in the range of 140 ° F or less, the linseed oil being uncured. b) application of an encapsulation layer of polymeric material before the precoverage is cured, the encapsulation layer being applied in a proportion of about five to ten parts per hundred of the weight of the center; and c) curing the precoat and the encapsulation layer at 140 ° F or more. . The process of claim 34, characterized in that the center has a sphericity of 50% or less and the controlled release fertilizer exhibits 4% or less of cumulative release in two hours in the ART-80 laboratory test when the encapsulation coverage it is 8 parts per hundred of the weight of the center or less.