Moisture-curing composition

Abstract

Embodiments of this disclosure relate to compositions for forming a coating on granules such as fertilizer granules.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to compositions for preparing coatings, particularly moisture-curable compositions for preparing coatings.

Background Art

[0002] Handling fertilizers in the form of pellets involves the inherent problem of dust. Dust occurs not only when dried pellets are dropped from a significant height onto a deposit for storage, but also when transported using conveyor belts and air conveyors. The generation of dust has at least two drawbacks. First, there is a significant reduction in the material in smaller and finer particles, which affects the amount of fertilizer and economy. This contributes to a second drawback, namely that consumers cannot utilize and distribute fertilizer dust / fine powder as effectively as pellets to meet the nutrient needs of crops.

[0003] In response to these problems, manufacturers have tried various methods to control the generation of dust and fine powder in their manufacturing processes. Coatings or dust control agents (DCAs) have been used to create a protective barrier around each pellet to help preserve the integrity and form of the granules. Commonly used DCAs currently in use rely on liquid-phase coating applications of waxes and oils, which are often applied at high temperatures (e.g., 100 °C or higher) to manage their viscosity. Such waxes and oils physically adhere to the surface but often do not cover the fertilizer uniformly, which can result in lifespan problems. For example, the dust control performance of fertilizers coated with waxes and oils can decrease over time because they lack chemical reactivity. Furthermore, a significant amount of time is required to cool the fertilizer after the application of waxes and oils, which affects productivity.

[0004] While two-component (2K) systems have demonstrated usefulness, the need for multiple reagents (e.g., isocyanates and polyols) makes it difficult, if not impossible, for customers to use existing oil / wax coating equipment for this alternative approach. Therefore, single-component (1K) isocyanate-terminated moisture-curable coatings may prove advantageous in that they do not require further asset expansion (i.e., a drop-in solution). Although these systems are useful, they also have significant processability issues due to their high room-temperature viscosity, which may require high temperatures for rheological ease. Furthermore, there are issues centered on the pot life and storage stability of such prepolymers. In addition, the cost of prepolymer materials may be difficult to match (i.e., too high) to match the cost of existing DCAs such as oils and waxes. Moreover, while polymer isocyanates exhibit attractive rheological and dust control properties in the case of 1K coatings, they generally have very slow moisture curing for forming high-performance polyurea shells. The coating should adhere uniformly in a liquid state sufficiently well to provide initial protection and dust control, and in this case, the curing behavior should be fast enough to provide a lifetime of protection for the granules. This should then allow the encapsulated granules to move around the equipment without cracking or generating fine powder. [Overview of the Initiative]

[0005] This disclosure provides a single-component system in which an isocyanate compound pre-reacts with an isocyanate-reactive component to form an isocyanate-terminated composition, which can then undergo ambient moisture curing and crosslinking to form a polyurethane-urea coating. For this purpose, this disclosure provides a moisture-curable composition for producing a coating, the moisture-curable composition comprising 99 to 99.99 weight percent (Wt%) of a polymeric methylene diisocyanate having a functional value of 2.1 to 2.5 and 0.01 to 1 Wt% of a tertiary amino-triol having a molecular weight of 100 to 500 grams / mol, where 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 amino-triol totals 100 Wt%.

[0006] The above summary of this disclosure is not intended to describe each disclosed embodiment, nor to describe all embodiments of this disclosure. More specifically, this specification illustrates exemplary embodiments. In several places throughout this application, guidance is provided through lists of examples, which can be used in various combinations. In all cases, the enumerated lists serve only as representative groups and should not be construed as exclusive lists. [Modes for carrying out the invention]

[0007] This disclosure provides a single-component system in which an isocyanate compound pre-reacts with an isocyanate-reactive component to form an isocyanate-terminated composition, which then undergoes ambient moisture curing and crosslinking to form a polyurethane-urea coating. The polyurethane-urea coating can have good water barrier properties combined with mechanical strength such as tensile strength and elastic modulus.

[0008] Embodiments of the present disclosure encompass polyurethane-urea coatings formed from a single-component moisture-curing system. For this purpose, the present disclosure provides a moisture-curing composition for producing a coating, the moisture-curing composition comprising 99 to 99.99 weight percent (W%) of a polymeric methylene diisocyanate having a functional value of 2.1 to 2.5 and 0.01 to 1 W% of a tertiary amino-triol having a molecular weight of 100 to 500 grams / mol, where W% is based on the total weight of the moisture-curing composition. In one embodiment, the W% of the polymeric methylene diisocyanate and the tertiary amino-triol totals 100 W%. An exemplary use of polyurethane urea coatings is for the encapsulation of particulate materials such as fertilizer granules (e.g., water-soluble fertilizers), thereby forming a polyurethane "encapsulated material" from which the particulate material is periodically released, even when the particulate material is placed in a water-rich environment.

[0009] For various embodiments, polymeric methylene diisocyanates have a functional value of 2.1 to 2.5. All individual values ​​and subranges for the 2.1 to 2.5 functionality are incorporated herein. For example, polymeric methylene diisocyanates can have a functional value ranging from the lower limit of 2.1, 2.15, 2.2, or 2.25 to the upper limit of 2.5, 2.45, 2.4, or 2.35. Exemplary ranges of functional values ​​include 2.1 to 2.4, 2.2 to 2.4, and 2.25 to 2.35. As will be understood by those skilled in the art, the isocyanate functional value refers to the number of isocyanate (NCO) groups per molecule (e.g., polymeric methylene diisocyanate).

[0010] The polymeric methylene diisocyanates used to form polyurethane-urea coatings are aromatic isocyanates, such as aromatic organic polyisocyanates. The polyurethane-urea coatings are formed in a process that may involve the use of a single reaction mixture used to form the final product, or it may involve multiple distinct reaction mixtures applied at different stages to form the final product.

[0011] For various embodiments, the polymeric methylene diisocyanate may contain at least one selected from the group consisting of phenyl groups, benzyl groups, and toluene groups. Examples of polymeric methylene diisocyanates include methylene diphenyl 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 includes a mixture of oligomeric polyisocyanate and MDI isomers having a lower 2,4'-MDI isomer content compared to 4,4'-MDI. With respect to MDI isomers, PMDI may contain about 50% to 99% by weight of 4,4'-MDI isomers and about 50% to 1% by weight of 2,4'-MDI isomers, in which case the weight percentage is based on the total weight of MDI isomers in PMDI. In another embodiment, PDMI may contain about 75% to 99% by weight of 4,4'-MDI isomers versus about 25% to 1% by weight of 2,4'-MDI isomers, in which case the weight percentage is based on the total weight of MDI isomers in PMDI. In yet another embodiment, PDMI may contain about 85% to 99% by weight of 4,4'-MDI isomers versus about 15% to 1% by weight of 2,4'-MDI isomers, in which case the weight percentage is based on the total weight of MDI isomers in PMDI.

[0012] For various embodiments, the polymeric methylene diisocyanate may contain 29–33.5% by weight of isocyanate (NCO), where the weight percentage is based on the total weight of the polymeric methylene diisocyanate. All individual values ​​and partial ranges for 29–33.5% by weight of NCO are incorporated herein. For example, the weight percentage of NCO in a polymeric methylene diisocyanate may range from a lower limit of 29, 30, or 31 to an upper limit of 33.5, 33, 32.5, or 32. Exemplary ranges of weight percentage of NCO in a polymeric methylene diisocyanate may include 29.5–33.5% by weight of NCO, 30–33.5% by weight of NCO, and 31–33% by weight of NCO.

[0013] Examples of commercially available polymeric methylene diisocyanates for the purposes of this disclosure include PAPI® 94 (The Dow Chemical Company, DOW), Lupranate® 78 (BASF), Lupranate® 230 (BASF), Lupranate® 234 (BASF), Lupranate® 241 (BASF), Lupranate® 245 (BASF), Lupranate® 5010 (BASF), and Mondur® MRS-20 (Bayer).

[0014] For various embodiments, the moisture-curable composition for producing the coating further comprises 0.01 to 1% by weight of a tertiary aminotriol, where the weight percentage is based on the total weight of the moisture-curable composition. Furthermore, for various embodiments, the weight percentages of the polymeric methylene diisocyanate and the tertiary aminotriol total 100% by weight, where the weight percentage is based on the total weight of the moisture-curable composition. Such embodiments thus provide that the moisture-curable composition of the present disclosure may essentially consist of a polymeric methylene diisocyanate and a tertiary aminotriol as provided herein. Furthermore, such embodiments provide that the moisture-curable composition consists of a polymeric methylene diisocyanate and a tertiary aminotriol as provided herein.

[0015] For various embodiments, the tertiary amino-triol has a molecular weight of 100 to 500 g / mol. All individual values ​​and partial ranges for the molecular weight of 100 to 500 g / mol in tertiary amino-triols are included herein. For example, a tertiary amino-triol can have a molecular weight ranging from a lower limit of 100, 110, 120, 130, or 140 g / mol to an upper limit of 500, 400, 300, 200, or 160 g / mol. Exemplary ranges of molecular weight for tertiary amino-triols include 110 to 400, 120 to 300, 130 to 200, and 140 to 160 g / mol. For various embodiments, in certain embodiments, the tertiary amino-triol is triethanolamine. Triethanolamine has a molecular weight of about 149 g / mol, in which case the amine hydrogen equivalent (AHEW, g / eq) is about 50 g / eq. Other tertiary aminotriols are also possible. A further advantage of using triethanolamine is recognized as being that it becomes part of the curing network, in contrast to other possible amine catalysts [e.g., DMDEE-4,4'-(oxydiethane-2,1-diyl)dimorpholine] which may leach from the resulting coating while promoting the reaction between isocyanate and water.

[0016] In forming a coating from a polymeric methylene diisocyanate and a tertiary amino-triol, the moisture-curable composition has a molar ratio of 0.2 moles or less of tertiary amino-triol per 9 moles of isocyanate in the polymeric methylene diisocyanate. For example, the moisture-curable composition may have a molar ratio of 0.2 moles to 0.01 moles of tertiary amino-triol per 9 moles of isocyanate in the polymeric methylene diisocyanate. All individual values ​​and partial ranges for the molar ratio of 0.2 moles to 0.01 moles of tertiary amino-triol per 9 moles of isocyanate in the polymeric methylene diisocyanate are included in and disclosed herein. For example, the range of 0.2 moles to 0.01 moles of tertiary amino-triol per 9 moles of isocyanate may include tertiary amino-triols from a lower limit of 0.01, 0.05, or 0.1 moles per 9 moles of isocyanate to an upper limit of 0.2, 0.17, or 0.15 moles per 9 moles of isocyanate.

[0017] For various embodiments, the moisture-curable composition may be one in which a tertiary amino-triol is present in an amount of 0.1 to 0.5% by weight based on the total weight of the moisture-curable composition. All individual values ​​and partial ranges of the tertiary amino-triol present in the moisture-curable composition in terms of weight percent are included herein and disclosed herein. For example, the amount of tertiary amino-triol can range from a lower limit of 0.1, 0.15, or 0.2% by weight to an upper limit of 0.5, 0.45, 0.4, or 0.3% by weight.

[0018] According to an exemplary embodiment, the moisture-curable composition for producing a coating comprises 99% by weight of a polymeric methylene diisocyanate having a functional value of 2.2 to 2.4 and 1% by weight of triethanolamine, where the weight percentage is based on the total weight of the moisture-curable composition. In another exemplary embodiment, the moisture-curable composition for producing a coating comprises 99.5% by weight of a polymeric methylene diisocyanate having a functional value of 2.2 to 2.4 and 0.5% by weight of triethanolamine, where the weight percentage is based on the total weight of the moisture-curable composition. In yet another exemplary embodiment, the moisture-curable composition for producing a coating comprises 99.9% by weight of a polymeric methylene diisocyanate having a functional value of 2.2 to 2.4 and 0.1% by weight of triethanolamine, where the weight percentage is based on the total weight of the moisture-curable composition.

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

[0020] For various embodiments, the reaction of a polymeric methylene diisocyanate with a tertiary amino-triol, and the subsequent storage of the moisture-curable composition, are carried out in an environment that is essentially moisture-free (e.g., water-free). As used herein, an environment that is essentially moisture-free has less than 0.005 percent water (%Mv) based on the volume of the environment. An example of a preferred environment would be nitrogen gas with less than 0.005 percent water based on the volume of nitrogen.

[0021] For various embodiments, the moisture-curing compositions of the present disclosure can be used to coat various granular materials. Examples of such granular materials include fertilizer granules. Suitable fertilizer granules that can be coated with the moisture-curing compositions of the present disclosure include, for example, natural and synthetic fertilizers. For example, the fertilizer granules may be calcium-based, magnesium-based, sulfate-based, or phosphate-based granules. The fertilizer granules may be used to form encapsulated fertilizer particles containing 0.5% to 15% by weight of the moisture-curing composition of the present disclosure, based on the total weight of the encapsulated fertilizer particles.

[0022] According to exemplary embodiments, coatings formed by the moisture-curing compositions of the present disclosure may be produced by using an apparatus for mixing the moisture-curing compositions of the present disclosure with granules (e.g., fertilizer granules) in the amounts and conditions provided herein. Examples of such apparatus include, but are not limited to, rotary drum coaters, batch coating mixers, and tumble spray coating drums, among several coating techniques and apparatuses.

[0023] For various embodiments, a method for coating fertilizer granules as provided herein may include providing fertilizer granules and coating the fertilizer granules with a moisture-curing composition as provided herein at a reaction temperature of 20 to 100°C for a time sufficient to form a cured, non-stick surface as provided herein (less than 24 hours). Other suitable reaction temperatures for coating fertilizer granules include 20 to 80°C, 40 to 80°C, and 40 to 60°C. The method for coating fertilizer granules can be carried out in an environment containing sufficient moisture to form a coating from the moisture-curing composition of this disclosure. For example, relative humidity of 20 to 60 percent relative to a given reaction temperature is suitable for coating fertilizer granules with the moisture-curing composition of this disclosure.

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

[0025] For various embodiments, surfactants can be used to adjust the bubble size and / or to stabilize the coating formed from the moisture-curable composition when the moisture-curable composition expands and cures. One type of useful silicone surfactant is the polydimethylsiloxane type. Another useful type of silicone surfactant has a polysiloxane backbone modified with poly(oxyalkylene groups). Mixtures containing at least one surfactant of each type can be used.

[0026] When carrying out the reaction between a polymeric methylene diisocyanate and a tertiary amino-triol as described herein, the total amount of catalyst used can be from 0.0015 to 5 parts by weight, more specifically from 0.01 to 1 part by weight, per 100 parts by weight of the aromatic isocyanate. The catalyst for the reaction between the polymeric methylene diisocyanate and the tertiary amino-triol can be either 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′-tetramethylhexamethylenediamine, 1,2-dimethylimidazole, and tin compounds such as tin(II) acetate, tin(II) octanoate, tin(II) laurate, dibutyltin dilaurate, dibutyltin dimaleate, dioctyltin diacetate, and dibutyltin dichloride. The catalysts are optionally used alone or as mixtures thereof.

Examples

[0027] The following examples are provided for illustrative purposes only and are not intended to define or limit the embodiments in any way.

[0028] In Examples (Ex) and Comparative Examples (CE), various terms and names related to materials are used, for example, the following.

[0029] [Table 1] EW - equivalent weight (g) OH# - hydroxyl value (KOH / g) Functionality - number of isocyanate (NCO) groups per molecule

[0030] [Table 2] *The index refers to the calculated value of the molar ratio of NCO to isocyanate - reactive end groups (OH or NH). **%NCO is calculated by the formula: %NCO = [((molar NCO - molar OH) * 42.02) / total mass] * 100. ***The liquid state refers to the observation of free - flowing behavior and the absence of significant solid formation. ****The moisture - curing behavior and curing time were determined by the formation of a cured non - sticky surface.

[0031] [Table 3]

[0032] Uncoated fertilizer granules showed a dust reduction of 0.0135%. The coated formulation was applied at a total granule mass of 1.2% by weight. Tack-free cure time is the time it takes for a wooden tongue depressor to be introduced into the composition and removed without stringing or residue adhering to the tongue depressor. The relative NCO:urea ratio, determined by FTIR spectroscopy, reveals the degree of moisture hardening over time.

[0033] Comparative Example A did not form a film (no accelerated moisture curing effect) or a gel over a period of 7 days (168 hours (h)): this sets the baseline for what happens when isocyanates (PMDI) spontaneously cure through reaction with atmospheric moisture: the absence of a catalyst component results in insufficient moisture curing properties for the intended purpose of the target application.

[0034] Comparative Examples B, C, and H demonstrate that TEA incorporation ranging from 10% by weight, which causes the solution to gel, to 2% by weight, which causes some noticeable thickening of the solution, suggests that there is a low tolerance range for compositional stability with respect to TEA in PAPI® 94 polymer MDI.

[0035] Comparative Example D, in which TMP is used, shows solid separation upon cooling to room temperature: most importantly, there is no enhancement of curing activity: generally, adding a component that does not possess catalytic activity to an isocyanate component can be expected to result in insufficient moisture curing properties for the intended purpose of the target application.

[0036] Comparative Example E shows that glycerol, another short-chain crosslinking agent that does not have an amine functional group, yields a liquid product with good stability, but does not improve the moisture curing ability of the isocyanate, similar to Comparative Example D.

[0037] Comparative Example F is surprising in that MDEA (methyldiethanolamine), a diol functional group with a similarly expected tertiary amine, does not mix smoothly at a 1% by weight incorporation, but rather forms gelled aggregates upon addition and mixing.

[0038] Comparative Example G, which uses DETA (diethylenetriamine), shows that even with a content of 0.5% by weight of amine terminal groups and reactive NH species, the reactivity is too high to provide a stable composition.

[0039] Comparative Example I was obtained using MDEA at a low addition level, but even in this case there was some solid formation, which made this solution unacceptable for its intended use.

[0040] Examples 1, 2, and 3 were characterized by the use of small amounts of TEA, which exhibited highly accelerated moisture-curing behavior under ambient conditions, with non-stick curing observed after 24 and 48 hours, respectively. These examples of the present invention compared to the comparative examples clearly demonstrate the importance of the triethanolamine used, and their stability highlights the importance of a narrow, acceptable range of TEA addition. Viscosity data reveal that only minimal changes in viscosity were observed even after one month for the compositions shown as Examples 1, 2, and 3 versus Comparative Example A. These data indicate that even in the presence of small amounts of TEA, the compositions retain their rheological advantages as free-flowing materials at room temperature (e.g., 23°C). Dust control measurements for Comparative Example A, Examples 1, and 2 reveal that the compositions maintain high-performance dust control, while FTIR measurements of the coated granules reveal significantly enhanced moisture-curing behavior, as shown by Examples 1 and 2, which indicates better polymer formation and therefore longer coating solution life.

[0041] Experimental Procedure Viscosity Measurement: Each composition in the proportions shown in Table 2 was added to a Flakteck cup of appropriate size to produce 100 grams (g) of total material. The composition was then mixed for 30 seconds at 2300 revolutions per minute (rpm) using a Flakteck, Inc. Speedmixer. The material was then packed into the cup with nitrogen and sealed to minimize further introduction of air / moisture. After 28 days, the sample was visually inspected to confirm that no gelation had occurred. It was then poured into a 250 mL plastic three-necked container, and its viscosity was measured using a Stormer viscometer (BYK Instruments-bko-visc DS model, using the as-received rotating impeller) rotating at 200 rpm according to ASTM D562.

[0042] Non-stick time measurement: To test the formation of non-stick coatings exhibiting ambient moisture curing behavior, the mixed composition was added to a FlackTek cup and mixed for 30 seconds at 2300 rpm using a FlackTek, Inc. speed mixer. Subsequently, approximately 15 g of the material was poured into the lid of a small aluminum paint can placed in a well-ventilated fume hood and observed visually for 7 days. The material was inspected daily to determine the formation of a solidified non-stick coating with a liquid portion at the bottom (exhibiting ambient moisture curing behavior). The hardening of the non-stick coating was tested by bringing a wooden tongue depressor into contact with the top of the poured material and pulling it away. If no stringing or wetting of the tongue depressor was observed, the hardening of the non-stick coating was confirmed, and the observation time was recorded. The laboratory space in which the sample was held and observed was measured to have a percentage relative humidity (%RH) of 48-52% and a temperature of 20-22°C (measured using a ThermoFisher Traceable® portable temperature and humidity probe) during the test period.

[0043] The difference between moisture-induced film hardening and gelation is that film formation involves a solidified layer on top of the liquid, while the rest of the solution remains liquid. Gelation, on the other hand, occurs uniformly throughout the entire solution, indicating that hardening is primarily due to a catalyst or possible phase separation, rather than curing by ambient humidity in the atmosphere.

[0044] Dust control measurement: Ammonium sulfate-based prill (1 kilogram, kg) was placed in a homemade steel rotary drum coater with a diameter of 16 3 / 8 inches, a depth of 5 1 / 8 inches, and five equally spaced 1-inch bevels, and rotation was started at 40 rpm. Addition of the coating material was started. The component formulation (12 g or 1.2 wt%) as the proportion of the fertilizer to be coated was pre-weighed and added to the fertilizer all at once by syringe. After rotating the fertilizer for 1 minute, the material was discharged from the coater and left under ambient conditions until analysis.

[0045] The dust reduction procedure consists of the following steps: (a) riffling, (b) pre-grinding sieving to remove fine particles present before grinding, (c) grinding in a ball mill to intentionally generate fine particles, (d) post-grinding sieving to separate the generated fine particles from the grinding medium and crude fertilizer particles, and (e) calculation of the percentage of dust.

[0046] Riffling: A chute riffler (Humboldt H-3964 riffler) is used to eliminate sampling variation. When particles are coated in a drum coater, there is variation inherent in the coating process, which causes in-batch variation. The chute riffler divides the sample into two equal halves, thereby reducing variation between the two parts of the sample. This process is repeated multiple times, thereby reducing the variation in each iteration to the desired amount.

[0047] Sieving: Lab RO-TAP® screens were used to separate the grinding medium and fertilizer particles of different sizes. Screens of sizes 4750 μm (#4 mesh), 4000 μm (#5 mesh), and 850 μm (#20 mesh) were used in stacks. The first two sieves functioned to separate the grinding medium from the fertilizer pellets, while the last screen (#20 mesh) separated the fertilizer pellets from the finer fertilizer particles.

[0048] Ball mill grinding: The sample was sieved before grinding to remove fine particles smaller than 850 microns and eliminate all initial dust. The weight of coarser particles larger than 850 microns was recorded in m20. These coarse fertilizer particles were then placed in a grinding jar with 1930 g of grinding medium. A tall water bottle (diameter = 114 mm, height = 254 mm) was used as the grinding jar. An EDEMET ball mill was used to rotate the grinding jar at 70 rpm for 30 minutes. After grinding, the sample was sieved to separate the grinding medium, coarse fertilizer (>850 microns), and fine particles (<850 microns). The weight of the coarse fertilizer particles was recorded in m20.

[0049] The total dust percentage is calculated, and the abrasion performance of the tested sample is quantified as the difference in fertilizer weight of coarse fertilizer particles (>850 microns) before and after grinding, and this is normalized by the initial weight of the coarse fertilizer particles.

[0050] IR Measurement: FTIR measurements of coated granules were collected after 5 days at ambient laboratory temperature (23°C) and humidity (40% RH). In each case, PAPI® 94 coatings containing triethanolamine (0.1-0.5%) were found to exhibit higher curing than PAPI® 94 alone (Comparative Example A). This effect was most evident in the observation of the relative ratio of NCO to urea (the expected product formed by moisture curing). Example 1 showed the maximum amount of urea formed by the surface curing mechanism, while the 0.1 wt% triethanolamine sample (Example 2) and the PAPI® 94 sample (Comparative Example A) showed a decrease in the NCO:urea ratio in that order, as expected. Comparative Example A showed a normalized relative intensity ratio of 3.85 for NCO:urea. Example 2, using 0.1 wt% TEA in PAPI® 94, showed a relative ratio of 3.40, while Example 1, using 0.5 wt% TEA in PAPI®, showed a relative ratio of 2.37. A lower NCO:urea ratio indicates that a greater degree of moisture curing occurs in different coated samples over the same period. FTIR spectra were collected using a Thermo Nicolet 6700 FTIR spectrometer at 2270 cm⁻¹. -1 NCO stretching and 1650cm -1 The relative ratio of chemical species was determined using the measured intensity of the carbonyl C=O stretching of urea, which was estimated at [location].

Claims

1. A moisture-curable composition for manufacturing a coating, wherein the moisture-curable composition is A polymeric methylene diisocyanate (PMDI) having a functional value of 2.1 to 2.5 in 99 to 99.99 weight percent (wt%) and 0.01 to 1% by weight of a tertiary amino-triol having a molecular weight of 100 to 500 grams / mol Includes, The aforementioned weight % is based on the total weight of the moisture-curing composition. Moisture-curing composition.

2. The moisture-curable composition according to claim 1, wherein the PMDI contains about 50% to 99% by weight of a 4,4'-methylenediphenyl diisocyanate isomer and about 50% to 1% by weight of a 2,4'-methylenediphenyl diisocyanate isomer, and the weight percentage is based on the total weight of the 4,4'-methylenediphenyl diisocyanate isomer and the 2,4'-methylenediphenyl diisocyanate isomer.

3. The moisture-curable composition according to claim 1 or 2, wherein the polymeric methylene diisocyanate has a functional value 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 moles or less of the tertiary amino-triol per 9 moles of isocyanate in the polymer 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 to 0.5% by weight based on the total weight of the moisture-curable composition.

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

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

9. Fertilizer granules coated with the moisture-curing composition according to any one of claims 1 to 8.

10. A method for coating fertilizer granules, To provide fertilizer granules, Coating the fertilizer granules with the moisture-curing composition described in any one of claims 1 to 8 at a temperature of 20 to 100°C, A method that includes this.

Images