Methods for producing polyurea powder, gel and grease, and related compositions produced therefrom.

Abstract

A method for producing a urea-containing powder by simultaneously injecting an amine and an isocyanate into a mixing chamber is disclosed. The method involves mixing in a high-pressure impingement mixer at a pressure of at least 2500 psi for a time period of less than 10 seconds. The resulting urea-containing powder has a defined particle size and molecular weight distribution and a stoichiometric molar ratio of isocyanate and amine functional groups. Also disclosed are a method for producing a thickened polyurea-containing masterbatch with the urea-containing powder using a shear thickening process, and a method for producing a grease by heat gelling a first or second urea-containing powder in the presence of an oil.

Description

Technical Field

[0001] [Cross - Reference to Related Applications] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 055,031, filed Jul. 22, 2020, the entire content of which is hereby incorporated by reference and made a part of this specification.

[0002] The present disclosure generally relates to a method for producing polyurea - containing powder by reacting isocyanate and amine through an ultra - high - pressure mixing and sizing process. Also disclosed are methods for producing a gel from such powder using a continuous shear - driven process, and methods for producing a polyurea grease having excellent mechanical stability and high - temperature properties.

Background Art

[0003] Polyurea grease has attracted wide attention due to its high - temperature stability and low - noise characteristics due to its unique organic - type thickener compared to conventional metal - based soap greases such as lithium - based grease. Lithium - based grease currently has a grease market share of over 70%, but is facing a crisis because the lithium supply is expected to be strained due to the rapid growth of electric vehicles. On the other hand, although polyurea grease has the potential to replace lithium grease, it has faced problems and difficulties in production because it has conventionally been produced in situ at high temperatures often exceeding 200°C by reacting isocyanates such as MDI and TDI with amines in the presence of a base oil.

[0004] The pre - formed thickener approach, which first forms a polyurea thickener and then reacts the thickener with a base oil to achieve polyurea grease, is very attractive to many because it removes the difficulties in managing the toxicity and hazards of isocyanate and amine raw materials. In the first prior art (Patent Document 1) that discloses a continuous reaction screw, a thickener capable of achieving a desired grease substance with consistency and processability could not be obtained.

[0005] Patent Document 2 describes using a high-shear continuous mixer with in situ mixing of isocyanate and amine, using a liquid to produce a masterbatch, and then recovering a dried powder having a broad particle size distribution.

[0006] Spray drying at medium pressure (Patent Document 3) uses a large excess of solvent, which is considered impractical for commercial operations, and the recovered dried powder (poly)urea particles were in a ratio of 10:100 to 80:100 relative to the total weight of the solvent. In this composition and other solvent-based prior art compositions, the particle size distribution that directly affects the structural stability of the grease is not defined.

[0007] Patent Document 4 discloses an encapsulation approach for producing powder using a high-pressure impactor. Clogging in the impactor was observed in the absence of a liquid diluent. However, in the presence of a diluent, the powder became porous and sponge-like, and in this case as well, it had a wide particle size distribution.

[0008] The presence of liquid diluents such as solvents and base oils limits the practicality for large-scale and widespread commercial production. Large particle size and broad distribution have a direct and immediate impact on the subsequent grease manufacturing process and the performance of the final grease product, leading to reduced thickener yield, as well as decreased high-temperature stability and structural stability. These points highlight the difficulties and challenges in the production of polyurea preform thickeners. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] U.S. Patent No. 5,314,982 [Patent Document 2] International Publication No. 2020006234 [Patent Document 3] U.S. Patent Application Publication No. 2006 / 0052261 [Patent Document 4] U.S. Patent No. 7,923,421 [Overview of the project] [Problems that the invention aims to solve]

[0010] There is a need for a non-metallic grease with a soap-like structure that exhibits high-temperature stability, low noise characteristics, good mechanical and oxidative properties, and high shear stability. Therefore, one objective of the present invention is to develop a commercially viable, energy-saving process for producing a novel preform polyurea thickener composition that has unique and clearly defined particle size characteristics in the art and possesses consistency and reliability / performance that could not be achieved previously. [Means for solving the problem]

[0011] In view of the above, and in order to overcome the problems associated with the prior art, a method for producing a urea-containing powder is described, comprising simultaneously injecting at least one liquid amine and at least one liquid isocyanate into a mixing chamber. The mixing chamber comprises at least one high-pressure impaction mixer, which is used to mix the amine and isocyanate under high pressure, e.g., at least 2500 psi, for a period of time that substantially no unreacted isocyanate is formed. The mixing time for mixing in the impaction mixer is typically less than 10 seconds, e.g., 0 to 5 seconds, and a powder having an average particle size (D50) represented as D1 and a molecular weight distribution (D90-D50) represented as DD1 is obtained.

[0012] In one embodiment, the method further includes supplying a first urea-containing powder to a sizing device to form a second urea-containing powder having an average particle size (D50) represented as D2, which is smaller than D1, and a molecular weight distribution (D90-D50) represented as DD2, which is smaller than DD1.

[0013] By the method described, a urea-containing powder composition having a stoichiometric molar ratio of isocyanate and amine functional groups is produced.

[0014] In one embodiment, the method described herein further includes at least one shear thickening step of forming a thickened polyurea-containing masterbatch. In this embodiment, the shear thickening step includes a continuous shear-driven process that includes mixing a dry powder containing a urea-containing powder and at least one base oil, and mixing the dry powder and the base oil at a weight ratio in the range of 5 / 95 to 95 / 5.

[0015] In yet another embodiment, the method described herein further includes forming a polyurea grease by heat-gelatinizing at a temperature in the range of, for example, 100°C to 180°C for the first or second urea-containing powder or room temperature to 160°C for the urea-containing masterbatch in the presence of oil to form a gelled product, and pulverizing the gelled product to produce a polyurea grease having a smooth consistency and texture. The resulting grease has been shown to have excellent thermal stability, as evident from a dropping point of at least 250°C.

[0016] Apart from the subject matter discussed above, the present disclosure includes a number of other features as described below. Both the above description and the following description are merely exemplary.

[0017] The accompanying drawings are incorporated herein and form a part of this specification.

Brief Description of the Drawings

[0018] [Figure 1] It is a schematic diagram showing a system and method related to an embodiment for manufacturing a urea-containing dry powder according to the present disclosure. [Figure 2] It is a schematic diagram showing a system and method related to an embodiment for manufacturing a urea-containing masterbatch according to the present disclosure. [Figure 3] It is a schematic diagram showing a system and method related to an embodiment for manufacturing a urea-containing grease according to the present disclosure.

Embodiments for Carrying Out the Invention

[0019] Definition: As used herein, a "collision device", also known as a "collision mixer", refers to a mixing device that causes high-speed flows of multiple liquids to collide within a small chamber. The collision jet configuration typically creates a turbulent flow that mixes the precursor liquids, namely the amine and isocyanate, as they flow out of the chamber.

[0020] As used herein, the term "dropping point" of grease is an indicator of the heat resistance of grease and is the temperature at which it transitions from a semi-solid to a liquid state under specific test conditions. This is determined by the type of thickener used, as well as the cohesiveness of the oil and thickener in the grease.

[0021] As used herein, "gel or gelling" or any variation thereof means that a thickening substance is formed between the base oil and the first and second urea-containing powders.

[0022] As used herein, "high-temperature stability" means having a dropping point of at least 250 °C, for example at least 260 °C, and further at least 290 °C.

[0023] As used herein, "structural stability" means that the NLG grease grade change from 60 strokes to 100,000 strokes is less than 1 NLGI grade and the consistency (P w ) number is less than 15.

[0024] As used herein, "base oil (Groups I, II, III, IV, and V)" refers to, but is not limited to, naphthenic oils, synthetic naphthenic oils such as alkylbenzenes, diphenyl ethers, biphenyls, and alkylated naphthalenes. These oils are preferred due to their inherent high stability and solvency that result in a higher grease yield (lower thickener dosage).

[0025] As used herein, the term "ultrafine," as used to describe polyurea thickening agent powder, means that the D50 diameter, as determined by laser light scattering, is in the range of 0.1 to 200 microns, e.g., 0.1 to 100 microns, or even 0.1 to 50 microns, and the particle size distribution (D90-D50) is 100 microns, e.g., 50 microns, or even 25 microns.

[0026] As used herein, “smooth consistency” means the absence of identifiable or measurable lumps or other irregularities.

[0027] As used herein, “residence time” means the time that the amine and isocyanate remain in the mixing chamber before leaving the chamber.

[0028] As used herein, “ultra-high pressure” as used with respect to the mixing chambers (or multiple chambers) and apparatus (or apparatus) herein means pressures greater than 2000 psi, for example, greater than 2500 psi, greater than 3000 psi, and up to 7000 psi. The range of these specific endpoints, for example, pressures in the range of 2500 psi to 7000 psi and any range in between, are also included in this definition.

[0029] As used herein, the “NLGI Consistency Number” (sometimes referred to as “NLGI Grade”) represents a measure of the relative hardness of a grease used for lubrication, as defined by the standard classification of lubricating greases established by the Lubricating Grease Institute of America (NLGI). NLGI numbers range from 000 to 6, reflecting increasing hardness with increasing numbers. For example, NLGI number 000 defines a semi-fluid grease, and NLGI number 6 grease is very hard. NLGI number 2 grease is considered “normal” grease, and NLGI number 4 grease is considered very hard.

[0030] As used herein, "penetration" is the depth measured in 10-millimeter increments when a cone of a certain weight is inserted into grease, in accordance with ASTM D217.

[0031] As used herein, "ΔP100000" refers to the degree of mixing (P) from 60 strokes to 100,000 strokes. w ) It is a number change.

[0032] A novel process for producing urea-containing powders (which may be more than one) in the form of pure ultrafine powder, also referred to herein as “polyurea grease thickener compositions.” In one embodiment, the urea-containing powders described herein can be produced in the absence of any solvent or base oil. They can also be produced using negligible amounts of solvent or base oil. In either case, the disclosed powders have clearly defined particle sizes that effectively result in polyurea greases with consistency and processability, as well as excellent high-temperature stability and structural stability. The disclosed urea-containing powders achieve the performance required for greases by incorporating all necessary components, including, but not limited to, various base oils and additives known in the industry.

[0033] Therefore, according to the first embodiment described herein, with reference to Figure 1, the ultra-high pressure mixer 100 simultaneously receives at least one amine (130-feed A) and at least one isocyanate (125-feed I) under ultra-high pressure. In one embodiment, feeds A (130) and I (125) are supplied to the mixing chamber via a fixed or variable pump that discharges stoichiometric equivalents to ensure complete formation of the urea functional group. These feeds are typically in liquid form and are introduced into a mixing chamber 110 equipped with one or more impactors at a temperature in the range of room temperature to 120°C, for example, 50°C to 100°C, and a back pressure greater than 2000 psi, for example, at least 2500 psi or 3000 psi to 7000 psi, sufficient to maintain the feeds in liquid form.

[0034] In one embodiment, the impactor described herein and used has pore diameters, dimensions, and shapes ranging from flat to textured, which are required to achieve residence times of less than 10 seconds, e.g., less than 5 seconds or even less than 3 seconds. In another embodiment, the residence time is also determined by the feed temperature and the ultra-high pressure applied to the impactor. The resulting urea-containing powder is formed in a mixing chamber having a first particle size D1 (D50, determined by laser light scattering) and particle size distribution DD1 (D90-D50), which is then fed into a sizing (grinding / grinding) device 140 (135) to obtain powder 145 having a more narrow, clearly defined average particle size D2 (D50, determined by laser light scattering) of 0.1 microns to 200 microns, e.g., 0.1 microns to 100 microns, or even 0.1 microns to 50 microns, and a particle size distribution (D90-D50) of up to 100 microns, e.g., 50 microns, or even up to 25 microns. As described above, in various embodiments, the urea-containing powder described herein can be produced in the absence of any solvent or base oil, in the use of a negligible amount of solvent or base oil, or in the use of a predetermined amount of base oil(s) or solvent(s).

[0035] A second embodiment disclosed herein, with reference to Figure 2, is disclosed, comprising a continuous shear drive process 200, for example, a shear drive device 210, such as a twin-screw extruder, which simultaneously supplies polyurea ("PU") thickening agent powder produced according to the first embodiment, for example, as described with reference to Figure 1, and at least one solvent or base oil. In one embodiment, the powder produced according to the first embodiment is continuously supplied to the shear drive device 210. In this second embodiment, the polyurea powder is mixed with a suitable base oil in a weight ratio of 5 / 95 to 95 / 5 to form a thickened polyurea masterbatch 220. The thickened polyurea masterbatch 220 can be produced in various forms, including noodles, pallets, or pastes, with an average particle size (D50) of 0.1 to 200 microns, for example, 0.1 to 100 microns, or even 0.1 to 50 microns.

[0036] According to a third embodiment disclosed herein, with reference to Figure 3, the polyurea masterbatch 220 produced by the second embodiment is further processed in a suitable mixing / grinding apparatus, which includes, for example, a high-speed mixer, a pin or ball mill, or any other suitable apparatus such as a homogenizer known in the art, to produce polyurea grease 320. The methods herein for producing polyurea grease are carried out under thermal conditions substantially lower than known prior art methods, for example, from room temperature to 140°C, for example to 120°C, or even to 100°C.

[0037] In addition, the resulting polyurea grease 320 has a smooth fibrous texture along with excellent high-temperature stability and structural stability. According to various embodiments disclosed herein, the polyurea grease has structural and thermal stability, as is evident from its dropping point of 250°C or higher, for example, 260°C or higher, or even 290°C or higher.

[0038] Polyurea-containing powder In one embodiment as described herein, a method for producing a polyurea-containing powder includes simultaneously injecting a liquid amine (feed A) and a liquid isocyanate (feed I), collectively referred to as a "liquid precursor," into a mixing chamber equipped with one or more impactors, under ultra-high pressure and temperature conditions.

[0039] The temperature conditions are high enough to maintain the liquid state of the feed as the liquid is supplied through one or more impactors, and the back pressure conditions are high enough, such as above 2000 psi, above 2500 psi, for example from 3000 psi to 7000 psi.

[0040] The total residence time of the liquid precursor in the mixing chamber is not limited but depends on the chamber design, pressure, and temperature. In various embodiments, the residence time is less than 10 seconds, e.g., less than 5 seconds, or even less than 3 seconds, and in some cases instantaneously. The residence time also varies depending on the properties of the precursor, e.g., the functional groups and molecular weight of the isocyanates and amines used. For example, for certain aromatic isocyanates and aliphatic amines such as methylenediphenyl diisocyanate (MDI), the residence time is less than 15 seconds, less than 12 seconds, less than 10 seconds, less than 5 seconds, or even less than 3 seconds, or even shorter. Failure to control the residence time can lead to clogging requiring the introduction of a solvent or oil, potentially causing a fundamental change in the integrity / form / composition of the polyurea thickener from a dry powder to a paste or spongy / wet powder.

[0041] According to the present invention, the polyurea powder produced after the ultra-high pressure mixing chamber can be used for subsequent grease conversion. However, since the aim is to further optimize the grease yield, it is highly desirable to supply the powder through a sizing chamber that yields a clearly defined average particle size (D50) of 0.1 to 200 microns, e.g., 0.1 to 100 microns, e.g., 0.1 to 50 microns, and a particle size distribution (D90-D50) of 100 microns, e.g., 50 microns, or even down to 25 microns.

[0042] In one embodiment, the sizing apparatus is operated in continuous and batch processes at temperatures ranging from room temperature to 160°C by sizing techniques such as air classification, air jets, pin or ball mills, or pneumatic or mechanical impact mills including hammer / screen mills, although this is not limited to these methods.

[0043] According to one aspect of this disclosure, the polyurea thickener can be exemplified as an isocyanate, which is methylenediphenyl diisocyanate (MDI) and toluene diisocyanate (TDI), respectively:

[0044] [ka] Amines (R1 and R2) represent chemical substances having an amine functional group, including aliphatic, alicyclic, aromatic amines, primary or secondary, linear or branched mono or diamines, alcohol or alkoxy-containing amines, or other amine derivatives, and mixtures thereof.

[0045] Examples of such amines include, but are not limited to, aliphatic amines such as lauryl, stearyl, or fat amines, cyclohexyl and dicyclohexylamines, benzylamines, aniline, diamines such as ethylenediamine, and mono or polyetheramines such as Jeffamine M or D.

[0046] The chemical properties and molar ratios of the amines are varied as desired to achieve the rheology and performance required for the grease. In one embodiment, the molar ratio varies from 1 / 99 to 99 / 1, as exemplified by diurea compositions using MDI and monoamines, such as aliphatic amines and cycloalkylamines. In other embodiments, amines such as monoamines and diamines or amines having other functional groups are used. The mixing chamber needs to be appropriately adjusted so that the desired molar ratio of isocyanate (Figure 1, 125-feed I) to total amine (Figure 1, 130-feed A) is matched and urea formation is fully achieved.

[0047] In another embodiment, alkanolamines, such as ethanolamine, or other functionalizing amines that allow for a slightly excess of isocyanate and impart an alcohol functional group to the resulting polyurea thickener can be used.

[0048] In yet another embodiment, when an amine derivative is selected, for example, when a mixture of amines is used, aromatic amines are selected rather than aliphatic amines, and their ratio affects the resulting grease performance.

[0049] Isocyanates such as MDI (methylenediphenylenediisocyanate) and TDI (toluene diisocyanate) are the two most common choices in the grease industry. Other options, such as polymers and isomers of MDI, are also certainly possible.

[0050] Polyurea masterbatch According to one aspect of the present disclosure, the polyurea thickener masterbatch shown in Figure 2 is prepared by simultaneously feeding ultrafine powder (Figure 1, according to the first embodiment) and an optimal base oil in a weight ratio of 5 / 95 to 95 / 5 through a twin-screw extruder using a continuous shear drive device such as a twin-screw extruder. The extruder used is designed to further control the particle size of the thickener by providing a range from mild shear to maximum shear. By controlling the flow of the powder / base oil mixture through the narrow gap between the screw and the wall, the operator has another variable to adjust and provide both the maximum grinding effect and the resulting properties in the polyurea masterbatch. The resulting masterbatch may be in the form of noodles, pallets, or pastes with an average particle size (D50) of 0.1 to 200 microns, for example, 0.1 to 100 microns, or even 0.1 to 50 microns.

[0051] In one embodiment, the described continuous shear drive device can provide preformed polyurea thickener in various forms with even smaller particle sizes, such as noodles, extruded products, or pastes, while significantly reducing process conditions, such as the temperature requirements for grease conversion, and eliminating the need for subsequent grinding.

[0052] In one embodiment, if a harder grease is desired, the base oil can be used in amounts up to 80%. When these amounts are added to a twin-screw extruder, a polyurea grease with an NLGI grade of 4 or higher is formed. To produce a softer grease, the base oil can be used in amounts exceeding 80%. In this way, a polyurea grease with an NLGI grade of 2 or higher is obtained by the twin-screw extruder.

[0053] In one embodiment, it will be considered by those skilled in the art that, in addition to a twin-screw extruder, alternative shear-driven mixing devices, such as a rotor-stator mixer, an internal mixer, such as a Banbury mixer, an extruder, or a homogenizer, are applicable to facilitate the shear thickening process in the use of polyurea powder.

[0054] In one embodiment, the type of base oil used in the production of the masterbatch is not limited, but may be paraffinic or naphthenic (groups I / II / III) or any type of synthetic base oil (groups IV and V), or naphthenic oils, synthetic naphthenic oils, such as alkylbenzenes, diphenyl ethers, biphenyls and alkylated naphthalenes, are preferred due to their inherent high stability and dissolving power, resulting in a higher grease yield (lower thickener dosage).

[0055] Grease conversion via fine powder and masterbatch In one embodiment, an ultrafine polyurea thickener powder prepared according to the first embodiment (Figure 1) is gelled in the presence of a base oil, such as a hydrocarbon base oil, at a temperature in the range of 100°C to 180°C, for example, 120°C to 160°C, or even 140°C to 160°C. Gelation can be carried out in a normal grease kettle for 2 to less than 6 hours until the mixture is thickened to an effective dose of 10% to 25% based on the content of the urea-containing composition from the first and second powders. After thickening, heating to the kettle is usually stopped within 30 minutes thereafter. The remaining oil and additives such as antioxidants, extreme pressure agents or anti-wear agents, rust inhibitors, pour point depressants, adhesives, polymers, or other additives are added while cooling and grinding to the final / desired consistency of the grease. The present disclosure makes it possible to produce NLGI No. 2 polyurea grease with a urea thickener dose of 6% to 12%.

[0056] In another embodiment, the final grease is produced as shown and described in Figure 3. For example, the final grease is produced using a polyurea masterbatch produced according to the second embodiment (shown and described in Figure 2) with a suitable mixing / grinding apparatus. Suitable mixing / grinding apparatuses contemplated herein include, but are not limited to, high-speed mixers, pneumatic or mechanical mills, conventional grease kettles, contactors and homogenizers, or any other suitable wet dispersion apparatus.

[0057] As shown in Figure 3, polyurea grease with a smooth fibrous texture, as well as excellent high-temperature and structural stability, can be manufactured using a process far simpler than those described in the prior art. For example, the grease can be manufactured under thermal conditions ranging from room temperature to 140°C, for example, 120°C, or even down to 100°C. In addition, the grease can be formed without the grinding and crushing steps often required in current commercial processes. [Industrial applicability]

[0058] The disclosed polyurea-containing grease, polyurea-containing powder, and masterbatches manufactured from the powder, as well as related embodiments including methods for manufacturing the same, can be used in applications requiring stability under extreme lubrication conditions such as high temperature, high speed, and / or high load. Nonmetallic greases manufactured according to the principles of this disclosure exhibit improved properties in the form of high-temperature stability, low noise characteristics, good mechanical and oxidative properties, and high shear stability. Therefore, nonmetallic greases manufactured according to the principles of this disclosure can be used in applications such as permanently sealed bearings, ball bearings, and electric motors.

[0059] The following examples will better illustrate the features and advantages of this disclosure, but they are provided for illustrative purposes only and should not be construed as limiting the invention. [Examples]

[0060] The following examples disclose a polyurea-containing dry powder, a masterbatch composition containing the dry powder, and a method for producing grease from the dry powder.

[0061] Example 1 In this example, animal fat and a 1:1 molar mixture of cyclohexylamine and isocyanate were simultaneously supplied without solvent or base oil through a variable ratio pump to an ultra-high pressure mixing chamber having chamber dimensions such as orifice size and chamber length sufficient to accommodate residence times ranging from over 0 seconds to 3 seconds and a pressure of 3000 psi. The resulting ultrafine dried powder had an average particle size of 50 microns (D50) and contained no unreacted isocyanate. This was then supplied to a continuous sizing apparatus to obtain an average particle size of 10 microns.

[0062] Example 2 In this example, animal fat in a molar ratio of 3:7, cyclohexylamine, and isocyanate were simultaneously supplied to an ultra-high pressure mixing chamber at a pressure of 3000 psi, according to Example 1.

[0063] Examples 3 and 4 Animal fat, cyclohexylamine, and isocyanate were simultaneously supplied to an ultra-high pressure mixing chamber at a pressure of 3500 psi in a molar ratio according to Examples 1 and 2.

[0064] Examples 5, 6, 7, 8, 9 and 10 In these examples, the ratio and functional groups of animal fat and amines such as cyclohexylamine (Examples 5 and 6 with added alkylated naphthalene ("AN23") base oil), dicyclohexylamine (Example 7), ethanolamine (Example 8), and Jeffamine D (Examples 9 and 10) were varied at a pressure of 4000 psi.

[0065] Grease conversion The first and second urea powders illustrated by all the above examples (1-10) readily gel at 160°C for 2 hours, and grease formation is completed within 4-6 hours after heating, during which a smooth grease is formed with excellent grease consistency and processability, as well as excellent structural stability and high-temperature stability, at a high dropping point exceeding 280°C (see Table 1). In the second urea powder after sizing, the processability and consistency of the grease are further improved (reduced number of grinding cycles), and the yield of the thickener increases.

[0066] Comparative Examples A and B Comparative Example A was prepared using 15% alkylated naphthalene and a commercially available impaction apparatus following the procedure shown in Example 2. Comparative Example B was prepared via a solvent (THF, tetrahydrofuran) process. In Comparative Example A, the impaction apparatus continuously clogged during processing. Even after cleaning to remove the clogging, the apparatus continued to clog. In both comparative examples, the obtained urea powder did not gel within 2 hours at 160°C. Furthermore, extending the heating period resulted in a decrease in the consistency of the formed grease, requiring multiple grinding steps.

[0067] [Table 1]

[0068] Examples 13 and 14 - Masterbatch Generation The first urea powder (Example 2) and alkylated naphthalene (20cSt@100C) were fed into a twin-screw extruder at volume ratios of 20 / 80 and 80 / 20, respectively, at rates of 5 lbs to 500 lbs per hour. The resulting polyurea masterbatch was available in the form of a paste (Example 13, see Table 2) and a concentrated grease (Example 14), which could be further cut into pallets / extruded products. In the subsequent grease conversion, an additional AN23 base oil was used to obtain a polyurea grease with a final yield of 10%, reduced process time / temperature, less grinding, and excellent structural / mechanical stability.

[0069] [Table 2]

[0070] Other embodiments of the present invention will become apparent to those skilled in the art from the discussion herein and the practice of the present invention disclosed herein. This specification and the examples are intended to be merely illustrative, and the true scope of the present invention is indicated by the appended claims.

Claims

1. A method for producing urea-containing powder, The process involves simultaneously injecting at least one liquid amine and at least one liquid isocyanate into a mixing chamber equipped with at least one high-pressure impaction mixing device, The at least one amine and the at least one isocyanate are mixed in the at least one high-pressure impaction mixer at a pressure of at least 2500 psi for a period of less than 10 seconds, sufficient to form a first urea-containing powder substantially free of unreacted isocyanate. The first urea-containing powder has an average particle size (D50) represented as D1 and a particle size distribution (D90-D50) represented as DD1; The first urea-containing powder is supplied to a sizing device to form a second urea-containing powder having an average particle size (D50) represented as D2, which is smaller than D1, and a particle size distribution (D90-D50) represented as DD2, which is smaller than DD1. Furthermore, the second urea-containing powder composition has a stoichiometric molar ratio of isocyanate and amine functional groups; Methods that include...

2. The method according to claim 1, wherein D1 is in the range of 0.1 microns to 100 microns and DD1 is in the range of 1 micron to 100 microns.

3. The method according to claim 1, wherein D2 is in the range of 0.1 microns to 30 microns and DD2 is in the range of 1 micron to 50 microns.

4. The method according to claim 1, wherein the at least one amine and the at least one isocyanate are mixed in the chamber at a pressure in the range of 2500 psi to 7000 psi.

5. The method according to claim 1, wherein the mixing and supply are carried out continuously in the absence of a solvent and a base oil to produce a dry powder containing diurea or polyurea.

6. The method according to claim 1, wherein the mixing time is less than 5 seconds.

7. The method according to claim 1, wherein the first urea powder is produced in the presence of at least one solvent or base oil added together with the isocyanate, the amine, or both, in an amount that does not change the particle size characteristics of the powder.

8. The method according to claim 7, wherein the solvent is present in an amount of up to 50% by weight of the isocyanate, the amine, or both, and is stripped / removed after the production of the first urea powder.

9. The method according to claim 7, wherein the base oil is present in an amount of up to 30% by weight of the isocyanate, the amine, or both.

10. The method according to claim 1, wherein the amine functional group is selected from aliphatic, cyclic, aromatic amines, primary or secondary, linear or branched mono or diamines, alcohol or alkoxy-containing amines, amine derivatives, and mixtures thereof.

11. The method according to claim 1, wherein the amine is selected from lauryl, stearyl, or fat amines, cyclohexyl and dicyclohexylamines, benzylamines, aniline, diamines, mono or polyetheramines, and mixtures thereof.

12. The method according to claim 1, wherein the isocyanate is selected from methylenediphenyl diisocyanate and monomer or polymer toluene diisocyanate.

13. The method according to claim 1, wherein the sizing device is selected from a pneumatic or mechanical impact mill, or a combination thereof, the pneumatic impact mill includes an air classifier or an air jet, and the mechanical impact mill is selected from a pin mill, ball mill, hammer mill, or screen mill.

14. The method according to claim 1, further comprising at least one shear thickening step for forming a thickened polyurea-containing masterbatch, wherein the at least one shear thickening step comprises a continuous shear-driven process for mixing a dry powder containing the urea-containing masterbatch with at least one base oil, the dry powder and the base oil being mixed in a weight ratio in the range of 5 / 95 to 95 / 5.

15. The method according to claim 14, wherein the thickened polyurea-containing masterbatch is mixed using an apparatus selected from a twin-screw extruder, a rotor-stator mixer, an internal mixer, or a homogenizer.

16. The method according to claim 15, wherein the thickening polyurea-containing masterbatch is mixed in an apparatus that enables it to be extruded in the form of noodles, paste, or extruded material.

17. The method according to claim 16, wherein the noodles, paste, or extruded product comprises a urea-containing masterbatch having an average particle size (D50) in the range of 0.1 microns to 50 microns.

18. The method according to claim 14, wherein the base oil used in the production of the masterbatch is selected from paraffinic oils, naphthenic oils, hydrocracking oils (groups I / II / III), alkylbenzenes, group IV and V synthetic oils, or combinations thereof.

19. The method according to claim 15, wherein the masterbatch produced by a twin-screw extruder maintains or further reduces a particle size distribution D1, DD1, D2, DD2 or a combination thereof.

20. The method according to claim 1, further comprising heating and gelling the first or second urea-containing powder in the presence of oil to form a gel, and then grinding the gel to produce a polyurea grease having a smooth consistency and texture, and a dropping point of at least 250°C.

21. The method according to claim 20, wherein the heating and gelling is carried out in an open or sealed grease kettle, or any reaction vessel suitable for oil dispersion.

22. The method according to claim 20, wherein the gelation temperature is in the range of 100°C to 180°C.

23. The method according to claim 20, wherein grinding is performed using a three-roll colloid mill or homogenizer.

24. The method according to claim 14, further comprising: dispersing a first urea-containing masterbatch in the presence of oil using one or more dispersion containers to form a dispersion; and pulverizing the dispersion to produce a polyurea grease having a smooth consistency and a dropping point of at least 250°C.

25. The method according to claim 24, wherein the dispersion container is selected from a high-speed mixer, a pin mill, a ball mill, an open kettle, or any container suitable for oil dispersion.

26. The method according to claim 24, wherein the dispersion is carried out at a temperature in the range of room temperature to 160°C.

27. The method according to claim 16, wherein the noodles, paste, or extruded product comprises a urea-containing masterbatch having an average particle size (D50) of 0.1 microns to 5 microns.

28. The method according to claim 27, further comprising a polyurea grease composition manufactured in a masterbatch suitable for high-speed and low-noise grease applications.

29. The method according to claim 14, further comprising a continuous process for forming polyurea grease, wherein the continuous process supplies the base oil to the continuous shear drive process at a rate of more than 5,000 pounds per hour.

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