Moisture curable composition

Abstract

Embodiments of the present disclosure relate to a composition for forming a coating on granules, such as fertilizer granules.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to a composition for preparing a coating, and in particular, a moisture-curable composition for preparing a coating. Background Art

[0002] Handling fertilizers in pellet form is accompanied by an inherent dust problem. In addition to dust generation when dropped from considerable height into a pile for storage, dust is also generated when dry pellets are transported using conveyor belts and air conveyors. Dust generation has at least two disadvantages. First, there is a significant loss of material into smaller, finer particles, which affects the bulk and economy of the fertilizer. This in turn creates a second disadvantage, namely that fertilizer dust / fines cannot be utilized and distributed as effectively by the consumer as pellets to meet crop nutritional needs.

[0003] Faced with these challenges, manufacturers have tried different approaches to control the generation of dust and fines during the production process. Coatings or dust control agents (DCAs) have been used to create a protective barrier around each pellet, which helps maintain pellet integrity and morphology. Common DCAs currently used rely on liquid coating applications of waxes and oils, which are typically applied at elevated temperatures (e.g., 100°C and higher) to control their viscosity. Such waxes and oils physically adhere to the surface but typically do not evenly cover the fertilizer, which can cause service life issues. For example, fertilizers coated with waxes and oils may lose dust control properties over time due to their lack of chemical reactivity. In addition, it takes a considerable amount of time to cool the fertilizer after applying the waxes and oils, which affects productivity.

[0004] Two-component (2K) systems have shown utility, but the need for multiple reagents (e.g., involving isocyanates and polyols) makes it difficult or even impossible for customers to use their existing oil / wax coating equipment for this alternative approach. Therefore, the advantage of one-component (1K) isocyanate-terminated moisture-curing coatings is that there is no need to further expand the assets (i.e., drop-in solutions). These systems are useful, but there are also serious processing issues due to their high room temperature viscosity, which may require elevated temperatures to facilitate rheology. In addition, there are issues surrounding the shelf life and storage stability of such prepolymers. In addition, the cost of prepolymer materials may be difficult to match (i.e., too high) with the cost of existing DCAs (such as oils and waxes). In addition, for 1K coatings, polymeric isocyanates exhibit attractive rheological and dust control properties, but are generally quite slow when wet-cured to form a high-performance polyurea shell. The coating should be uniform and adhere well enough in the liquid state to provide initial protection and dust control, while the curing behavior is fast enough to provide long-term protection for the particles. This should then allow the encapsulated particles to move within the facility without breakage or generation of fines. Summary of the invention

[0005] The present disclosure provides a one-component system in which an isocyanate compound is pre-reacted with an isocyanate-reactive ingredient to form an isocyanate-terminated composition that can undergo ambient moisture curing and crosslinking to form a polyurethane-urea coating. To this end, the present disclosure provides a moisture-curable composition for producing a coating, comprising 99 weight percent (wt.%) to 99.99 wt.% of a polymeric methylene diisocyanate having a functionality of 2.1 to 2.5 and 0.01 wt.% to 1 wt.% of a tertiary aminotriol having a molecular weight of 100 g / mole to 500 g / mole, wherein the wt.% is based on the total weight of the moisture-curable composition. In one embodiment, the wt.% of the polymeric methylene diisocyanate and the tertiary aminotriol total 100 wt.%.

[0006] The above summary of the invention of the present disclosure is not intended to describe each disclosed embodiment or each embodiment of the present disclosure. The following description more specifically illustrates exemplary embodiments. In several places throughout this application, guidance is provided by example lists, which can be used in various combinations. In each case, the enumerated lists serve only as representative groups and should not be interpreted as exclusive lists. DETAILED DESCRIPTION

[0007] The present disclosure provides a one-component system in which an isocyanate compound is pre-reacted with an isocyanate reactive component to form an isocyanate terminated composition that can undergo ambient moisture curing and crosslinking to form a polyurethane-urea coating. The polyurethane-urea coating can have good water barrier properties as well as mechanical strength, such as tensile strength and elastic modulus.

[0008] Embodiments of the present disclosure encompass polyurethane-urea coatings formed by wet curing of a one-component system. To this end, the present disclosure provides a wet curable composition for producing a coating, comprising 99 weight percent (wt.%) to 99.99 wt.% of a polymerized methylene diisocyanate having a functionality of 2.1 to 2.5 and 0.01 wt.% to 1 wt.% of a tertiary amino triol having a molecular weight of 100 g / mol to 500 g / mol, wherein the wt.% is based on the total weight of the wet curable composition. In one embodiment, the wt.% of the polymerized methylene diisocyanate and the tertiary amino triol totals 100 wt.%. An exemplary use of a polyurethane-urea coating is for encapsulating particulate materials such as fertilizer particles (e.g., water-soluble fertilizers) to form a polyurethane "encapsulate" so that the particulate material is periodically released from the encapsulate even when the particulate material is placed in a water-rich environment.

[0009] For various embodiments, the polymeric methylene diisocyanate has a functionality of 2.1 to 2.5. All individual values ​​and subranges of functionality of 2.1 to 2.5 are included herein. For example, the polymeric methylene diisocyanate may have a lower range value of functionality of 2.1, 2.15, 2.2, or 2.25 to an upper range value of 2.5, 2.45, 2.4, or 2.35. Exemplary ranges of functionality include 2.1 to 2.4; 2.2 to 2.4; and 2.25 to 2.35. As will be appreciated by those skilled in the art, isocyanate functionality refers to the number of isocyanate groups (NCO) per molecule (e.g., polymeric methylene diisocyanate).

[0010] The polymeric methylene diisocyanate used to form the polyurethane-urea coating is an aromatic isocyanate, such as an aromatic organic polyisocyanate. The polyurethane-urea coating is formed in a process that may include the use of a single reaction mixture for forming the final product, or may include a plurality of separate reaction mixtures applied at different stages to form the final product.

[0011] For various embodiments, the polymeric methylene diisocyanate may include at least one selected from the group of phenyl, benzyl and tolyl. Exemplary polymeric methylene diisocyanates include diphenylmethane diisocyanate (MDI) and isomers of MDI (e.g., 2,2'-MDI, 2,4'-MDI and 4,4'-MDI); polymethylene polyphenyl isocyanate (PMDI), diphenylmethane-4,4'-diisocyanate, 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, 4,4',4"-triphenylmethane triisocyanate and dimethyldiphenylmethane tetraisocyanate. In one embodiment, PMDI comprises a mixture of oligomeric polyisocyanates and MDI isomers, with a low content of 2,4'-MDI isomers relative to 4,4'-MDI. With respect to MDI isomers, PMDI may contain from about 50 wt.% to 99 wt.%. In another embodiment, PDMI can contain about 75wt.% to 99wt.% 4,4'-MDI isomers to about 25wt.% to 1wt.% 2,4'-MDI isomers, wherein wt.% is based on the gross weight of MDI isomers in PMDI. In another embodiment, PDMI can contain about 85wt.% to 99wt.% 4,4'-MDI isomers to about 15wt.% to 1wt.% 2,4'-MDI isomers, wherein wt.% is based on the gross weight of MDI isomers in PMDI.

[0012] For various embodiments, the polymeric methylene diisocyanate may contain 29 wt.% to 33.5 wt.% of isocyanate (NCO), wherein the wt.% is based on the total weight of the polymeric methylene diisocyanate. All individual values ​​and subranges of 29 wt.% to 33.5 wt.% NCO are included herein. For example, the wt.% of NCO of the polymeric methylene diisocyanate may have a lower range value of 29, 30, or 31 to an upper range value of 33.5, 33, 32.5, or 32. Exemplary ranges of the wt.% of NCO of the polymeric methylene diisocyanate may include 29.5 wt.% to 33.5 wt.% NCO; 30 wt.% to 33.5 wt.% NCO and 31 wt.% to 33 wt.% NCO.

[0013] Commercial examples of polymeric methylene diisocyanates useful in the present disclosure include PAPI TM 94(The Dow Chemical Company.DOW); Lupranate TM 78 (BASF); Lupranate TM 230 (BASF); Lupranate TM 234 (BASF); Lupranate TM 241(BASF); Lupranate TM 245 (BASF); Lupranate TM 5010 (BASF); and Mondur TM MRS-20 (Bayer), etc.

[0014] For each embodiment, the wet curable composition for producing coating also includes 0.01wt.% to 1wt.% of tertiary amino triol, wherein wt.% is based on the gross weight of the wet curable composition. In addition, for each embodiment, the wt.% of polymerized methylene diisocyanate and tertiary amino triol totals 100wt.%, wherein wt.% is based on the gross weight of the wet curable composition. Such embodiments make the wet curable composition of the present disclosure can therefore be substantially composed of polymerized methylene diisocyanate and tertiary amino triol as provided herein. In addition, such embodiments make the wet curable composition be composed of polymerized methylene diisocyanate and tertiary amino triol as provided herein.

[0015] For each embodiment, tertiary amino triol has a molecular weight of 100 g / mol to 500 g / mol. All individual values ​​and sub-ranges of the molecular weight of 100 g / mol to 500 g / mol of tertiary amino triol are included herein. For example, tertiary amino triol can have a molecular weight of 100 g / mol, 110 g / mol, 120 g / mol, 130 g / mol or 140 g / mol lower range value to 500 g / mol, 400 g / mol, 300 g / mol, 200 g / mol or 160 g / mol upper range value. The exemplary range of the molecular weight of tertiary amino triol includes 110 g / mol to 400 g / mol; 120 g / mol to 300 g / mol; 130 g / mol to 200 g / mol; and 140 g / mol to 160 g / mol. For each embodiment, in a specific example, tertiary amino triol is triethanolamine. Triethanolamine has a molecular weight of about 149 g / mol and an amine hydrogen equivalent weight (AHEW, g / eq) of about 50 g / eq. Other tertiary amino triols are also possible. It is recognized that an additional benefit of using triethanolamine is that it becomes part of the curing network, as opposed to other possible amine catalysts [e.g., DMDEE-4,4'-(oxydiethane-2,1-diyl)dimorpholine], which can potentially leach out of the resulting coating while promoting the reaction of isocyanate and water.

[0016] When the coating is formed by polymerized methylene diisocyanate and tertiary amino triol, the wet curable composition has a molar ratio of 0.2 moles or less of tertiary amino triol / 9 moles of isocyanate in polymerized methylene diisocyanate. For example, the wet curable composition may have a molar ratio of 0.2 moles to 0.01 moles of tertiary amino triol / 9 moles of isocyanate in polymerized methylene diisocyanate. All individual values ​​and sub-ranges of the molar ratio of 0.2 moles to 0.01 moles of tertiary amino triol / 9 moles of isocyanate in polymerized methylene diisocyanate are included herein. For example, the range of 0.2 moles to 0.01 moles of tertiary amino triol / 9 moles of isocyanate may have a lower limit of 0.01 moles, 0.05 moles or 0.1 moles of tertiary amino triol / 9 moles of isocyanate to an upper limit of 0.2 moles, 0.17 moles or 0.15 moles of tertiary amino triol / 9 moles of isocyanate.

[0017] For various embodiments, the wet curable composition may be such that the tertiary amino triol is present in an amount of 0.1 wt.% to 0.5 wt.% based on the total weight of the wet curable composition. All individual values ​​and subranges of the wt.% of the tertiary amino triol present in the wet curable composition are included herein and disclosed herein. For example, the amount of the tertiary amino triol may have a lower limit of 0.1 wt.%, 0.15 wt.%, or 0.2 wt.% to an upper limit of 0.5 wt.%, 0.45 wt.%, 0.4 wt.%, or 0.3 wt.%.

[0018] According to an exemplary embodiment, the wet curable composition for producing the coating comprises 99 wt.% of a polymeric methylene diisocyanate having a functionality of 2.2 to 2.4 and 1 wt.% of triethanolamine, wherein the wt.% is based on the total weight of the wet curable composition. In another exemplary embodiment, the wet curable composition for producing the coating comprises 99.5 wt.% of a polymeric methylene diisocyanate having a functionality of 2.2 to 2.4 and 0.5 wt.% of triethanolamine, wherein the wt.% is based on the total weight of the wet curable composition. In yet another exemplary embodiment, the wet curable composition for producing the coating comprises 99.9 wt.% of a polymeric methylene diisocyanate having a functionality of 2.2 to 2.4 and 0.1 wt.% of triethanolamine, wherein the wt.% is based on the total weight of the wet curable composition.

[0019] For each embodiment, a wet curable composition for producing a coating is formed by mixing a type and amount of polymerized methylene diisocyanate and a tertiary amino triol as provided herein at a temperature in the range of, for example, 0°C to 100°C. The mixing time for forming the wet curable composition may be 30 seconds to 1 hour, depending on the temperature at which the polymerized methylene diisocyanate and the tertiary amino triol react. Shorter or longer reaction times are also possible. For each embodiment, the wet curable composition may have a viscosity in the range of 40 centipoise (cP) to 250 cP measured according to ASTM D4889.

[0020] For various embodiments, the reaction of the polymerized methylene diisocyanate and the tertiary aminotriol and the subsequent storage of the moisture-curable composition are in an environment that is substantially free of moisture (e.g., water). As used herein, an environment that is substantially free of moisture has less than 0.005% water based on the volume of the environment (%Mv). An example of a suitable environment is nitrogen, which has less than 0.005% water based on the volume of nitrogen.

[0021] For each embodiment, the wet curable composition of the present disclosure can be used to apply various granular materials. The example of such granular materials includes fertilizer particles. Suitable fertilizer particles that can be applied with the wet curable composition of the present disclosure include, for example, natural and synthetic fertilizers. For example, the fertilizer particles can be calcium-based, magnesium-based, sulfate-based or phosphate-based particles. The fertilizer particles can be used to form encapsulated fertilizer particles, based on the gross weight of the encapsulated fertilizer particles, which contain 0.5 weight % to 15 weight % of the wet curable composition of the present disclosure.

[0022] According to an exemplary embodiment, the coating formed by the wet curable composition of the present disclosure can be prepared by using a device that combines the wet curable composition of the present disclosure with particles (e.g., fertilizer particles) in the amounts and conditions provided herein. Examples of such equipment include, but are not limited to, a rotary drum coater, an intermittent coating mixer, a tumble spray coater, and other coating techniques and equipment.

[0023] For various embodiments, the method of coating fertilizer particles as provided herein may include providing fertilizer particles and coating the fertilizer particles with a wet curable composition as provided herein for a sufficient time at a reaction temperature of 20°C to 100°C so that the coating forms a hardened, non-sticky surface as provided herein (less than 24 hours). Other suitable reaction temperatures for the method of coating fertilizer particles include 20°C to 80°C; 40°C to 80°C and 40°C to 60°C. The method of coating fertilizer particles can be carried out in an environment including sufficient moisture to form a coating from the wet curable composition of the present disclosure. For example, for a given reaction temperature, a relative humidity of 20% to 60% is suitable for a method of coating fertilizer particles with a wet curable composition of the present disclosure.

[0024] When preparing a coating from the moisture-curable composition, the moisture-curable composition of the present disclosure may further include one or more additional components, such as at least one selected from the group consisting of surfactants, catalysts, emulsifiers, preservatives, flame retardants, colorants, antioxidants, reinforcing agents, and fillers.

[0025] For various embodiments, surfactants can be used to adjust the pore size and / or stabilize the coating produced by the wet curable composition as it expands and cures. One useful type of silicone surfactant is polydimethylsiloxanes. Another useful type of silicone surfactant has a polysiloxane backbone modified with a poly(oxyalkylene) group. Mixtures containing at least one surfactant of each type can be used.

[0026] When the reaction between the polymerized methylene diisocyanate and the tertiary amino triol as described herein is carried out, the total amount of the catalyst used can be 0.0015 to 5 parts by weight, more particularly 0.01 to 1 parts by weight per 100 parts by weight of aromatic isocyanate. The catalyst for the reaction between the polymerized methylene diisocyanate and the tertiary amino triol can be anionic or cationic. Exemplary catalysts include, for example, triethylamine, 1,4-diazabicyclo 2.2.2. octane (DABCO), N-methylmorpholine, N-ethylmorpholine, N,N,N',N'-tetramethylhexanediamine, 1,2-dimethylimidazole and tin compounds, such as tin acetate (II), tin octoate (II), tin laurate (II), dibutyltin dilaurate, dibutyltin dimaleate, dioctyltin diacetate and dibutyltin dichloride. The catalyst is optionally used alone or as a mixture thereof.

[0027] Example

[0028] The examples that follow are provided for illustration only and are not intended to define or limit the embodiments in any way.

[0029] In the Examples (Ex) and Comparative Examples (CE), various terms and names of materials are used, and these terms and names include, for example, the following:

[0030] Table 1 - Materials

[0031]

[0032] EW – Equivalent Weight (g)

[0033] OH#-Hydroxyl number (KOH / g)

[0034] Functionality - the number of isocyanate (NCO) groups per molecule.

[0035] Table 2 - Ex and CE Formulations

[0036]

[0037] *The index refers to the calculated molar ratio of NCO to isocyanate-reactive end groups (OH or NH).

[0038] **%NCO is calculated by the following equation: %NCO=[((mol NCO-mol OH)*42.02) / total mass]*100 ***Liquid means that free-flowing behavior is observed and no obvious solid formation.

[0039] ****Wet cure behavior and time are determined by the formation of a hardened tack-free surface.

[0040] Table 3 - Properties / Performance

[0041]

[0042] The uncoated fertilizer granules had a dust abrasion result of 0.0135%. The coating formulation was applied at 1.2 wt.% of the total granule mass. The tack-free cure time is the time at which a wooden tongue depressor can be introduced into the plating composition and pulled apart without stringing or residual material sticking to the depressor. The relative NCO:urea ratio determined by FTIR spectroscopy reveals the extent of wet cure over time.

[0043] CE A neither produces a skin (no accelerated moisture curing effect) nor forms a gel over a period of 7 days (168 hours (h)): it sets a baseline for the case where the isocyanate (PMDI) cures itself by reaction with atmospheric moisture: the lack of a catalytic component results in insufficient moisture curing properties for the purposes of the target application.

[0044] CE B, CE C, and CE H show that TEA incorporation increases from 10 wt.% (where the solution gels) to as low as 2 wt.% (where there is some significant thickening of the solution), indicating that for PAPI TM There is a low tolerance band for the stability of TEA compositions in 94 polymeric MDI.

[0045] CE D using TMP showed separation of solids upon cooling to room temperature: Most importantly, there was no enhanced curing activity: Generally speaking, it can be expected that the addition of ingredients without catalytic activity to the isocyanate component would result in insufficient moisture curing properties for the intended application purpose.

[0046] CE E shows that glycerol (another short-chain crosslinker without amine functionality) does not enhance the moisture curing ability of isocyanates, although it produces a liquid product with good stability, similar to CE D.

[0047] CE F is surprising in that MDEA (N-methyldiethanolamine) as the diol functionality does not mix smoothly with similar prospective tertiary amines at 1 wt.% incorporation, but forms a gelled aggregate upon addition and mixing.

[0048] CE G using DETA (diethylenetriamine) showed that the reactivity of the amine end groups and reactive NH species was too strong to provide a stable composition even at 0.5 wt. %.

[0049] CE I was obtained using low addition levels of MDEA, and even in this case there was some solid formation, which made the solution unacceptable for the intended use.

[0050] EX 1, EX 2 and EX 3 are characterized by the use of small amounts of TEA, which show highly accelerated wet curing behavior under ambient conditions, with 24 hours and 48 hours of tack-free curing observed, respectively. These inventive examples show the importance of the specific use of triethanolamine compared to the comparative examples, and their stability shows the importance of a narrow acceptable TEA loading range. The viscosity data reveal that for the compositions shown as EX 1, EX 2 and EX 3 versus CE A, even after 1 month, minimal changes in viscosity can be observed. They show that even in the presence of small amounts of TEA, the composition retains its rheological advantages as a free-flowing material at room temperature (e.g., 23° C.). Dust control measurements of CE A, EX 1 and EX 2 reveal that the compositions maintain high performance dust control, while FTIR measurements of the coated particles reveal that EX 1 and EX 2 exhibit significantly enhanced wet curing behavior, indicating better polymer formation and therefore longer coating solution service life.

[0051] Experimental Procedure

[0052] Viscosity measurement :Into the flakteck cup of suitable size, add each composition of the ratio shown in Table 2, to produce 100 grams (g) of total material.Then use FlackTek, Inc. fast agitator to mix the composition for 30 seconds (s) with 2300 revolutions per minute (rpm).After this, fill the material with nitrogen and seal the cup to minimize the further introduction of air / moisture.After 28 days, visual inspection sample is carried out to ensure that gelation does not occur.Then pour it into 250mL plastic three-pour cup (tripour), and use the Stormer viscometer (BYK Instruments-byko-visc DS type, using the received rotating impeller) rotating at 200rpm to measure its viscosity according to ASTM D562.

[0053] Tack-free time measurement: To test the non-sticky formation of the skin cure (which indicates environmental wet cure behavior), the mixed composition was added to a flackteck cup and mixed at 2300 rpm for 30 seconds using a FlackTek, Inc. fast mixer. Thereafter, approximately 15 g of the material was poured into a small aluminum paint can lid located in a well-ventilated fume hood and visually observed for more than seven days. The material was checked daily to determine the formation of a cured, non-sticky skin, as well as the liquid portion under the skin (which indicates environmental wet cure behavior). The non-sticky skin cure was tested by contacting a wooden tongue depressor to the top of the cast material and pulling it apart. When the tongue depressor was observed to be free of wire drawing or soaking, it indicated non-sticky skin cure, and the observation time was recorded. The laboratory space in which the samples were held and observed was measured to have the following ranges during the test: relative humidity percentage (%RH) = 48%-52%; temperature = 20°C to 22°C, as measured using a ThermoFisher Traceable TM Measured by portable temperature and humidity probes.

[0054] The difference between moisture-induced skin solidification and gelation is that the skin is produced as a solidified layer only in the upper half of the liquid, while the rest of the solution remains liquid. On the other hand, gelation occurs uniformly throughout the solution, suggesting that solidification is primarily due to a catalyst or possibly phase separation, rather than solidification with ambient moisture from the atmosphere.

[0055] Dust control measurements Ammonium sulfate-based granules (1 kilogram, kg) were placed in an in-house steel rotary drum coater with a 16 3 / 8 inch diameter and 5 1 / 8 inch depth, with five evenly spaced 1 inch ramps, and rotation was started at 40 rpm. Addition of coating material was started. The component formulation (12 g or 1.2 wt.%, as part of the fertilizer to be coated) was pre-weighed and added to the fertilizer all at once via syringe. The fertilizer was rotated for 1 minute, then the material was removed from the coater and allowed to remain at ambient conditions until analysis.

[0056] The dust grinding procedure consists of the following steps: (a) riffling; (b) screening before grinding to remove existing fines; (c) grinding in a ball mill to purposefully produce fines; (d) screening after grinding to separate the produced fines from the grinding media and coarse fertilizer particles; and (e) dust percentage calculation.

[0057] Powder extraction: Use chute powder extractor (Humboldt H-3964 powder extractor) to eliminate sampling variability. When coating particles in a drum coater, there is inherent variability in the coating process, which leads to intra-batch variability. The chute powder extractor divides the sample into two equal parts, thereby reducing the variability between the 2 samples. This process is repeated many times, thereby reducing the variability in each iteration to the desired amount.

[0058] filter :Use Lab The sieves separate the grinding media and the fertilizer particles of different sizes. A stack of sieves with sizes of 4750 μm (#4 mesh) and 4000 μm (#5 mesh) and 850 μm (#20 mesh) is used. The first two sieves are used to separate the grinding media from the fertilizer particles, and the last sieve (#20 mesh) separates the fertilizer particles from the fine fertilizer particles.

[0059] ball milling :Before grinding, the sample was sieved to remove fine particles below 850 microns to eliminate any initial dust. The weight of coarse particles greater than 850 microns was recorded as mi. Then, these coarse fertilizer particles were placed in a grinding jar with 1930g of grinding media. In this work, a high hydration water bottle (diameter = 114mm, height = 254mm) was used as a grinding jar. The jar was rotated at 70rpm for 30 minutes using an EDEMET ball mill. After grinding, the sample was sieved to separate grinding media, coarse fertilizer (>850 microns) and fine particles (<850 microns). The weight of the coarse fertilizer particles was recorded as m20.

[0060] The total dust percentage was calculated to quantify the abrasive performance of the test samples as the difference in fertilizer weight of the coarse fertilizer particles (>850 microns) before and after grinding, normalized to the initial weight of the coarse fertilizer particles.

[0061] IR Measurement : FTIR of the coated particles was collected after 5 days at ambient laboratory temperature (23°C) and humidity (40% RH). It was found that in each case, compared with PAPI alone TM Compared with 94, PAPI containing triethanolamine (0.1%-0.5%) TM The 94 coating showed higher cure (CE A). This effect is most pronounced when looking at the relative ratios of NCO to urea (the expected product formed by moisture cure), where, as expected, EX 1 shows the greatest amount of urea formed via a surface cure mechanism, while the 0.1 wt.% triethanolamine sample (EX 2) and PAPI TM The 94 samples (CE A) showed NCO:urea ratios decreasing in this order. CE A showed a relative normalized intensity ratio of NCO:urea of ​​3.85. TMEX 2 containing 0.1 wt.% TEA in 94 showed a relative ratio of 3.40, while in PAPI TM EX 1 with 0.5 wt.% TEA showed a relative ratio of 2.37. The lower NCO:urea ratio indicates that a greater degree of moisture curing occurred in the same period of time for the different coated samples. FTIR spectra were collected using a ThermoNicolet 6700 FTIR spectrometer with a wavelength of 2270 cm -1 NCO stretching at 1650cm -1 The relative ratios of the chemical species were measured by measuring the intensity of the carbonyl C=O stretch of the putative urea at .

Claims

1. A moisture-curable composition for producing a coating, the moisture-curable composition comprising: 99 weight percent (wt.%) to 99.99 wt.% of polymeric methylene diisocyanate (PMDI) having a functionality of 2.1 to 2.5; and 0.01 wt.% to 1 wt.% of a tertiary amino triol having a molecular weight of 100 to 500 g / mole, wherein the wt.% is based on the total weight of the moisture-curable composition.

2. according to the wet curable composition of claim 1, wherein said PMDI contains about 50wt.% to 99wt.% of 4,4'-diphenylmethane diisocyanate isomer and about 50wt.% to 1wt.% of 2,4'-diphenylmethane diisocyanate isomer, wherein said wt.% is based on the gross weight of said 4,4'-diphenylmethane diisocyanate isomer and said 2,4'-diphenylmethane diisocyanate isomer.

3. The moisture-curable composition of any one of claims 1 to 2, wherein the polymeric methylene diisocyanate has a functionality of 2.2 to 2.

4.

4. The moisture-curable composition according to any one of claims 1 to 3, wherein the moisture-curable composition has a molar ratio of 0.2 mol or less of the tertiary amino triol / 9 mol of isocyanate in the polymeric methylene diisocyanate.

5. The moisture-curable composition according to any one of claims 1 to 4, wherein the tertiary amino triol is present in an amount of 0.1 wt.% to 0.5 wt.% based on the total weight of the moisture-curable composition.

6. The moisture-curable composition of any one of claims 1 to 5, wherein the tertiary amino triol is triethanolamine.

7. The moisture-curable composition of any one of claims 1 to 6, wherein the moisture-curable composition consists essentially of the polymeric methylene diisocyanate and the tertiary amino triol.

8. The moisture-curable composition according to any one of claims 1 to 6, wherein the moisture-curable composition consists of the polymeric methylene diisocyanate and the tertiary amino triol.

9. A fertilizer granule coated with the moisture-curable composition according to any one of claims 1 to 8.

10. A method of coating fertilizer granules, the method comprising: Provide fertilizer granules; as well as The fertilizer granules are coated with the moisture curable composition according to any one of claims 1 to 8 at a temperature of 20°C to 100°C.

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