Slow cure hybrid polyurea

Abstract

A polyurea prepolymer prepared from a reaction mixture comprising 2, 4' and 4,4' methylene diphenyl diisocyanate; and at least one component selected from a secondary diamine chain extender and a secondary polymeric diamine. Also described is a method for producing a polyurea-polyurethane hybrid polymer and a polyurea-polyurethane hybrid polymer.

Description

[0001] Slow Cure Hybrid Polyurea

[0002] Cross Reference to other applications

[0003]

[0001] None

[0004] Background to the invention

[0005]

[0002] Polyurea is a type of elastomer that is derived from the reaction product of an isocyanate component and an amine component. Polyurea is often used as a waterproofing material in industrial and commercial settings to protect surfaces from water damage. It is applied as a liquid coating, which then quickly cures to form a durable, waterproof barrier. This can be used for waterproofing roofs, foundations, decks, and other surfaces. It can also be used to seal concrete structures, such as swimming pools, water tanks and retaining walls. Polyurea is known for its excellent resistance to water, chemicals, abrasion, and impact, which makes it an ideal option for waterproofing surfaces that are exposed to harsh conditions.

[0006]

[0003] Polyurea polymers often show fast curing and have a low or short pot life. Their applications are therefore often limited to application with spray-machines. There is therefore a need to develop a slow cure polyurea that can be applied by hand and has a long pot life.

[0007]

[0004] Multiple attempts have been made to prepare slow cure polyurea, predominantly by developing a hybrid polyurea-polyurethane polymer prepared by reacting a prepolymer comprising an isocyanate with diamine and polyol containing resins.

[0008]

[0005] Polyurea prepolymers have also been reported in the prior arts. For example, US20020107354A1, the contents of which are incorporated by reference herein, reports the synthesis of aliphatic polyurea prepolymer by reacting caprolactone monomer, aliphatic primary polyamine and aliphatic polyisocyanate. The polyurea prepolymer is added to a polyurethane composition. US2016229947A1 describes the synthesis of polyurea prepolymer or quasi-prepolymer by reacting isocyanate component (4,4' MDI or uretonimine-modified 4,4' MDI or hexamethylene diisocyanate (HDI) allophanate or HDI trimer or aliphatic HDI biuret) with secondary diamine. US4686242A demonstrates the preparation of polyurea prepolymer or quasi-prepolymer by reacting amine functional compound (with at least 400 equivalent weight) with an excess of polyisocyanate and developing a polyurea or polyurea-polyurethane prepolymer by reacting isocyanate reactive material with polyurea prepolymer. Finally, EP0529839A1 reports the synthesis of quasi-prepolymer by reacting a polyoxyalkylene polyamine with aliphatic polyisocyanate and developing a polyurea elastomer using the quasi- prepolymer, polyoxyalkylene polyamine and aromatic diamine. However, the prepolymers and the resin systems described in all these documents have shown only marginal improvements in the pot life (less than 30 minutes). They are therefore still mostly unsuitable for hand application.

[0009]

[0006] There is a need to develop a hybrid polyurea-polyurethane polymer which has a pot life of more than 30 min making it hand-applicable.

[0010] Object of the Disclosure

[0011]

[0007] It is an object of the present disclosure to provide a polyurea prepolymer which can be used in making a hybrid polyurea polymer which has a pot life of more than 30 min. Such a polymer would be capable of hand application.

[0012] Detailed Description

[0013]

[0008] The present disclosure will be described with respect to particular aspects and embodiments.

[0014]

[0009] It is to be noticed that the term "comprising", used in the claims, should not be interpreted as being restricted to the means listed thereafter; it does not exclude other elements or steps. It is thus to be interpreted as specifying the presence of the stated features, steps or components as referred to, but does not preclude the presence or addition of one or more other features, steps or components, or groups thereof. Thus, the scope of the expression "a compound comprising components X and Y" should not be limited to compounds consisting only of components X and Y. It means that with respect to the present disclosure, the only relevant components of the compound are X and Y.

[0015]

[0010] Throughout this specification, reference to "one embodiment" or "an embodiment" are made. Such references indicate that a particular feature, described in relation to the embodiment is included in at least one embodiment of the present disclosure. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment, though they could. Furthermore, the features or characteristics may be combined in any suitable manner in one or more embodiments, as would be apparent to one of ordinary skill in the art.

[0016]

[0011] It is to be understood that although preferred embodiments and / or materials have been discussed, various modifications or changes may be made without departing from the scope and spirit of this invention.

[0017]

[0012] The terms “preferred” and “preferably” refer to embodiments that may afford certain benefits, under certain circumstances. However, other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful and is not intended to exclude other embodiments from the scope of the present disclosure.

[0013] Where substituent groups are specified by their conventional chemical formula, written from left to right, they equally encompass the chemically identical substituents that would result from writing the structure from right to left, for example, -CH2O- is equivalent to -OCH2-.

[0014] The term “optional” or “optionally” means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where said event or circumstance occurs and instances where it does not.

[0018]

[0015] Throughout this disclosure, the term “about” is used to indicate that a value includes the inherent variation of error for the quantifying device, mechanism, or method, or the inherent variation that exists among the subject(s) to be measured. For example, but not by way of limitation, when the term “about” is used, the designated value to which it refers may vary by plus or minus ten percent, or plus or minus nine percent, or plus or minus eight percent, or plus or minus seven percent, or plus or minus six percent, or plus or minus five percent, or plus or minus four percent, or plus or minus three percent, or plus or minus two percent, or plus or minus one percent, or one or more fractions therebetween.

[0019]

[0016] The phrases “or combinations thereof’ and “and combinations thereof’ as used herein refers to all permutations and combinations of the listed items preceding the term. For example, “A, B, C, or combinations thereof’ is intended to include at least one of A, B, C, AB, AC, BC, or ABC and, if order is important in a particular context, also BA, CA, CB, CBA, BCA, ACB, BAC, or CAB. Continuing with this example, expressly included are combinations that contain repeats of one or more items or terms such as BB, AAA, CC, AABB, AACC, ABCCCC, CBBAAA, CABBB, and so forth. The skilled artisan will understand that typically there is no limit on the number of items or terms in any combination, unless otherwise apparent from the context. In the same light, the terms “or combinations thereof’ and “and combinations thereof’ when used with the phrases “selected from” or “selected from the group consisting of’ refers to all permutations and combinations of the listed items preceding the phrase.

[0020]

[0017] In a first aspect, there is provided a polyurea prepolymer prepared from a reaction mixture comprising: a) Methylene diphenyl diisocyanate (MDI) comprising a mixture of 2,4’ MDI and 4,4’ MDI; and b) At least one component selected from a secondary diamine chain extender and a secondary polymeric diamine.

[0021]

[0018] Hybrid Polyurea is a type of elastomer that is derived from the reaction product of an isocyanate prepolymer component, such as that described in the first aspect, and a resin component comprising at least one polyol and optionally at least one polyamine through step- growth polymerization. The isocyanate containing prepolymer is also referred to herein as a quasi-prepolymer.

[0022]

[0019] Methylene diphenyl diisocyanate (MDI) is an aromatic diisocyanate. MDI is found in three commonly appearing isomers. These vary by the positions of the isocyanate groups around the rings: 2,2'-MDI, 2,4'-MDI, and 4,4'-MDI as shown below:

[0023]

[0020] The 4,4' isomer is the most widely used isomer - this isomer is also commonly known as “pure MDI”. The use of an MDI comprising 2,4’ MDI and at least one component selected from a secondary diamine chain extender and a secondary polymeric diamine provides a better control over the reaction exotherm during the synthesis of the polyurea prepolymer. This polyurea prepolymer has a lower reactivity than commonly used prepolymers. When the resultant polyurea prepolymer is mixed with a resin component containing polyol and optionally a secondary diamine chain extender or a secondary polymeric diamine, the lower reactivity of polyurea prepolymer and polyol increases the curing time and therefore improves the pot life of the hybrid polyurea system.

[0024]

[0021] The term “aromatic” is intended to take its usual meaning. That is, it is an organic compound containing a planar unsaturated ring of atoms which is stabilized by an interaction of the bonds forming the ring, e.g., benzene and its derivatives.

[0025]

[0022] A “diisocyanate” is any compound comprising two isocyanate (-N=C=O) groups.

[0026]

[0023] Chain extenders typically align themselves with the stiff and largely immobile hard segments in polyurethane elastomers. The interaction between the soft and hard segments in a polyurethane elastomer impacts the physical properties such as elasticity, tensile strength, tear resistance, and elongation. Examples of chain extenders include low molecular weight (short chain) secondary diamines, low molecular weight diols and combinations thereof.

[0024] The produced prepolymer can be reacted with the resin component to form a polyureapolyurethane polymer which has a pot life in excess of forty minutes. Such a hybrid polyurea polymer can therefore be used for hand applications as well as in spray applications, if desired.

[0025] In some embodiments, the MDI comprises between about 0.1 wt% to about 50 wt% of 2,4’ MDI and between about 50 wt% to about 99 wt% 4,4’ MDI. In some embodiments, the MDI may additionally comprise 2,2’ MDI. In some embodiments, the MDI comprises between about 0 to about 8 wt% 2,2’ MDI.

[0027]

[0026] Without wishing to be bound by theory, it is believed that by controlling the concentration of 2,4’ MDI in the MDI isomer mixture, it is possible to finely tune the reaction exotherm during the polyurea prepolymer synthesis. The resultant polyurea prepolymer prepared using 2,4’ MDI is less reactive and therefore when it is mixed with the resin component, it tunes the curing time and pot life of the prepolymer polyol mixture.

[0028]

[0027] In some embodiments, the polyurea prepolymer comprises between about 20 wt% and about 90 wt% MDI based on the total weight of the reaction mixture. By modulating the amount of at least one component selected from a secondary diamine chain extender and a secondary polymeric diamine it is possible to control the hard block content of any resultant polyurea polymer.

[0029]

[0028] Polyurea is a block polymer comprising both hard and soft blocks. The soft blocks deliver flexibility, and the hard blocks deliver heat resistance. This block structure offers a good performance balance of flexibility, heat resistance, elastic recovery, abrasion resistance, and processability.

[0030]

[0029] In some embodiments, the chain extender is selected from the group consisting of secondary aliphatic amine, secondary aromatic amine, and sterically hindered diamines and mixtures thereof. Examples of secondary aliphatic amines include, but are not limited to, secondary aliphatic amine selected from the group consisting of N, N'-dialkylethylenediamine; N, N'-dialkyl- 1,2-diaminopropane; N, N'-dialkyl- 1,3 -diaminopropane; 4,4'-methylenebis(N- alkylcyclohexamine); l,4-di(alkylamino)cyclohexane; l-methyl-2,4-di(alkylamino)-3,5- dialkylcyclohexanes; N, N'-dialkyl isophoronediamine; l,3-di(l'methyl-l'- alkylaminoethyl)benzene; l,6-di(alkylamino)hexane; and mixtures thereof. Examples of secondary aromatic amines include, but are not limited to, those selected from the group consisting of N,N'-dialkylmethylenedianiline; N,N'-dialkylphenylenediamine; and mixtures thereof.

[0031]

[0030] In some embodiments, when present, the secondary polymeric diamine is selected from the group consisting of a secondary aliphatic amine, a secondary aromatic amine, and mixtures thereof. Any suitable secondary polymeric diamine may be used. The skilled person would understand which secondary polymeric diamines could be used. For example, the secondary polymeric diamine may comprise a secondary aliphatic amine selected from the group consisting of N,N'-Diisopropyl-polypropylene glycol diamine, or the secondary polymeric diamine may comprise a secondary aromatic amine.

[0032]

[0031] In some embodiments, the reaction mixture comprises: a) between about 25 wt% and about 90 wt% of MDI; b) between about 0 wt% and about 20 wt% secondary diamine chain extender; and c) between about 0 and about 75 wt% secondary polymeric diamine based on the total weight of the reaction mixture provided that the reaction mixture comprises at least one of component b) or c).

[0033]

[0032] As will be understood by the skilled person, as the concentration of the secondary polymeric diamine increases, the viscosity of the pre-polymer will increase which can lead to handling challenges. If the amount of MDI in the pre-polymer mix is too high, the pot life of any resultant polymer may be decreased.

[0034]

[0033] In an aspect is described a polyurea-polyurethane hybrid polymer prepared by reacting the prepolymer described above and a resin blend comprising at least one polyol and optionally a polyamine or a low molecular weight diamine or a mixture thereof.

[0035]

[0034] The produced polymer has a long pot life which is in excess of 40 min whilst maintaining good polymer properties.

[0036]

[0035] In some embodiments, the polyol used in the resin blend is a polyester polyol, a polyether polyol, a polycarbonate polyol, or a mixture thereof. Suitable polyols include but are not limited to poly ether polyols such as polyoxyethylene polyol (polyethylene glycol), a polyoxypropylene polyol (polypropylene glycol), a polytetrahydrofuran diol, a poly caprolactone diol and combinations thereof such as a polyethylene polypropylene polyol. Suitable examples of a polyester polyol include, but are not limited to, polyester polyols having terminal hydroxyl groups which may include those obtained by the reaction between dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, dodecanoic acid, phthalic anhydride, isophthalic acid, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, maleic anhydride, fumaric acid, itaconic acid and a polyhydroxy compound selected from the short chain polyols. Polyester polyols can be also obtained by the reaction between a lactone compound such as P-propiolactone, pivalolactone, 5-valerolactone, P-methyl-5-valerolactone, s-caprolactone. methyl-s-caprolactone, dimethyl-s-caprolactone, trimethyl-s-caprolactone and a polyhydroxy compound selected from the short chain polyols and combinations thereof.

[0037]

[0036] In some embodiments, the polyamine is a polymeric secondary diamine, a secondary amine chain extender, or a mixture thereof. Suitable examples of secondary diamines and secondary amine chain extenders are described above.

[0038]

[0037] In some embodiments, the resin blend further comprises at least one component selected from one or more defoamers, one or more moisture scavengers, castor oil, one or more pigments, and one or more plasticizers.

[0039]

[0038] A defoamer or an anti-foaming agent is a chemical additive that reduces and hinders the formation of foam. The terms anti-foam agent and defoamer are often used interchangeably. Any type of defoamer can be included in the resin mixture. Commonly used agents are insoluble oils, polydimethylsiloxanes and other silicones, certain alcohols, stearates, and glycols.

[0040]

[0039] Polymeric materials and their corresponding additives and fillers may have excessive moisture levels that can adversely affect the physical characteristics of the resulting finished composite. A moisture scavenger therefore removes moisture from the composition. Any suitable moisture scavenger may be used. Commonly used examples include molecular sieves, natural clay, calcium oxide, calcium chloride, and modified starch.

[0041]

[0040] Plasticizers increase the flow and thermoplasticity of a polymer by decreasing the viscosity of the polyol blend. Commonly used polymer plasticizers include citrates, benzoates, ortho-phosphates, terephthalates, adipates, azelates, sebacates, and trimellitates.

[0042]

[0041] In some embodiments, a mixture of the prepolymer and the resin blend has a pot life greater than 40 min at 25 °C and between 30-95% relative humidity. Preferably the pot life at 25 °C and between 30-95% relative humidity is between 1 hour and 1. 5 hours. As the relative humidity increases, the quality of any resulting coating may be affected.

[0043]

[0042] In an aspect there is provided a method for preparing a polyurea-polyurethane hybrid said method comprising mixing a polyurea prepolymer as described above and a resin composition as described above and curing.

[0044]

[0043] Curing can be performed at any suitable temperature and pressure, preferably at room temperature and pressure.

[0045]

[0044] The resultant polymer preferably has a pot life greater than 40 min, has a touch dry time less than or equal to 5 hours, a tack free time of less than or equal to 24 hours.

[0046]

[0045] Pot life is also known as the working time or useable life. Pot life is often thought of as the length of time that a mixed system retains a viscosity low enough to be applied to a surface at a specified temperature. In this case pot life, touch dry time and tack free time are measured at 25 °C. Touch dry time is the point at which a polymer surface is sufficiently dry such that it no longer flows nor sticks to a finger that touches it lightly. The polymer is not completely dry at this point. The tack-free time is the duration to which the polymer surface is no longer sticky and does not create a fingerprint when touched with a gloved finger. It can be seen to have dry properties. Tackiness is the state where the dry-to-touch polymer still feels sticky and has poor blocking resistance.

[0047]

[0046] The resultant polymer preferably has a hardness (Shore D) of greater than or equal to 40. The Shore D hardness scale ranges from 1 to 100. Harder materials have higher Shore D values than softer materials. It can be measured by any method known to the skilled person; for example, using a Shore durometer.

[0048]

[0047] The resultant polymer preferably has a tensile strength at break greater than or equal to 5 MPa. Tensile tests measure the force required to break a plastic sample specimen and the extent to which the specimen stretches or elongates to that breaking point. The polymer tensile strength is measured by any method known to the skilled person. For example, ASTM D412 is performed by applying a tensile force to a sample specimen and measuring various properties of the specimen under stress. It is conducted on a universal testing machine (also called a tensile testing machine) at tensile rates ranging from 1 to 500 mm / min until the specimen fails (yields or breaks).

[0049]

[0048] The resultant polymer preferably has an elongation at break of greater than or equal to 200%. Elongation at break, also known as fracture strain, is the ratio between changed length and initial length after breakage of the test specimen. It expresses the capability of polymer to resist changes of shape without crack formation. It can be measured by any method known to the skilled person.

[0050]

[0049] The resultant polymer preferably has an adhesion strength of greater than or equal to 1.5 N / mm2. Polymer adhesion strength can be measured using any method known to the skilled person. For example, ASTM D7234 is used to pull off the polymer coatings from the coated substrate.

[0051]

[0050] The resultant polymer preferably shows a weight loss of less than 150 mg when the abrasion strength is measured using Taber method with Hl 8 wheels as abrader and under a load of 1 kg, evaluated for 1000 cycles.

[0052]

[0051] The resultant cured polymer preferably has zero water permeability measured by the Karsten tube method.

[0052] In a further aspect is provided a hybrid polyurea produced by the method described above.

[0053]

[0053] In an embodiment, the hybrid polyurea produced by the method described above is applied to a surface using hand application or by spray application. Preferably, the polymer is applied using hand application.

[0054]

[0054] Examples

[0055]

[0055] More details and advantages will become obvious from the following examples.

[0056]

[0056] The following components were used:

[0057] Polyresyst F0520- Hybrid polyurea- Huntsman

[0058] Suprasec 3051- MI-50, MDI- Huntsman

[0059] Gpol 115- Branched castor oil based polyol- Purnima Group, India

[0060] Siliporite SA 1720- Molecular sieves- BASF

[0061] Castor oil- Merck

[0062] BYK 066N- Silicone defoamer- BYK

[0063] Suprasec 2038- MI-27, MDI- Huntsman

[0064] Jeffamine SD 2001- Poly etheramine- Huntsman

[0065] Unilink 4200- Aromatic Diamine Chain Extender- Dorf Ketal

[0066]

[0057] Example 1

[0067]

[0058] A polyurea prepolymer was synthesised using MI-50 (Suprasec 3051) (without chain extender) and polyurea-polyurethane hybrid coating.

[0068]

[0059] 80 g of MI-50 was added to a round bottom flask and stirred at 200 rpm at ambient temperature under a nitrogen blanket was provided. 20 g of Jeffamine SD 2001 was added dropwise under continuous stirring and nitrogen atmosphere. The mixture was allowed to react at 200 rpm for 3 h. The synthesized polyurea prepolymer was tested for its NCO value and viscosity. NCO value was measured using auto-titrator as per EN ISO 14896 standard test method. Viscosity was measured using Brookfield viscometer.

[0069]

[0060] Apolyol blend was prepared using 81.6 g Gpol 115, 6.47 g of Siliporite SA 1720, 6.47 g of castor oil and 1.95 g of BYK 066N. The required amount of above synthesized polyurea prepolymer was added to the polyol blend to obtain an index of 133 and coated on a teflon sheet or metal panels or concrete blocks. The equation for calculating the index is shown below:

[0070]

[0061]

[0062] Example 2

[0071]

[0063] Polyurea prepolymer synthesis using MI-27 (Suprasec 2038) (without chain extender) and polyurea-polyurethane hybrid coating

[0072]

[0064] 81.2 g of MI-27 was added to a round bottom flask and stirred at 200 rpm at ambient temperature under a nitrogen blanket was provided. 18.8 g of Jeffamine SD 2001 was added dropwise under continuous stirring and nitrogen atmosphere. The mixture was allowed to react at 200 rpm for 3 h. The synthesized polyurea prepolymer was tested for its NCO value and viscosity.

[0073]

[0065] Apolyol blend was prepared using 81.6 g Gpol 115, 6.47 g of Siliporite SA 1720, 6.47 g of castor oil and 1.95 g of BYK 066N. The required amount of above synthesized polyurea prepolymer was added to the polyol blend to obtain an index of 133 and coated on a teflon sheet or metal panels or concrete blocks.

[0074]

[0066] Example 3

[0075]

[0067] Polyurea prepolymer synthesis using MI-27 (Suprasec 2038) (with chain extender) and polyurea-polyurethane hybrid coating.

[0076]

[0068] 56.2 g of MI-27 was added to a round bottom flask and stirred at 200 rpm at ambient temperature under a nitrogen blanket. 39.6 g of Jeffamine SD 2001 was mixed with 4.2 g of Unilink 4200 in a separate container. The mixture of both the diamines was added dropwise to MI-27 under continuous stirring and nitrogen atmosphere. The mixture was allowed to react at 200 rpm for 3 h. The synthesized polyurea prepolymer was tested for its NCO value and viscosity.

[0077]

[0069] Apolyol blend was prepared using 81.6 g Gpol 115, 6.47 g of Siliporite SA 1720, 6.47 g of castor oil and 1.95 g of BYK 066N. The required amount of above synthesized polyurea prepolymer was added to the polyol blend to obtain an index of 133 and coated on a Teflon sheet or metal panels or concrete blocks.

[0078]

[0070] Comparative Example - Control Hybrid Polyurea coating (Standard)

[0079]

[0071] Commercially available hybrid polyurea, Polyresyst F0520, was spray coated on a Teflon sheet or metal panels or concrete block obtain the hybrid polyurea coatings.

[0080]

[0072] The NCO value of the prepolymer, viscosity of the prepolymer and resin blend, and pot life time, touch dry time, tack free time, hardness, tensile strength and elongation for the hybrid polyurea coatings are shown below in Table 1.

[0081]

[0073] Table 1: Results of the examples

[0082]

[0074] These results show that the hybrid polyurea polymers produced have desirable properties.

[0083]

[0075] While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Claims

What is claimed:

1. A polyurea prepolymer prepared from a reaction mixture comprising: i. methylene diphenyl diisocyanate (MDI) comprising a mixture of 2,4’ MDI and 4,4’ MDI; and ii. at least one component selected from a secondary diamine chain extender and a secondary polymeric diamine.

2. The polyurea prepolymer of claim 1, wherein the MDI comprises between about 0.1 to about 50 wt% of 2,4’ MDI, between about 50 to about 99 wt% 4,4’ MDI, and optionally between about 0 to about 8 wt% of 2,2' MDI based on the total amount of MDI.

3. The polyurea prepolymer of claim 1 or claim 2, wherein the polyurea prepolymer comprises between about 25 and about 90 wt% MDI based on the total weight of the reaction mixture.

4. The polyurea prepolymer of any preceding claim, wherein the chain extender is selected from the group consisting of secondary aliphatic amine, secondary aromatic amine, and sterically hindered diamines and mixtures thereof, preferably wherein the chain extender is a secondary aliphatic amine selected from the group consisting of N, N' -dialkylethylenediamine; N, N'-dialkyl- 1,2-diaminopropane; N, N'-dialkyl- 1,3-diaminopropane; 4,4'-methylenebis(N-alkylcyclohexamine); 1,4- di(alkylamino)cyclohexane; l-methyl-2,4-di(alkylamino)-3,5-dialkylcyclohexanes; N, N'- dialkyl isophoronediamine; l,3-di(rmethyl-l'-alkylaminoethyl)benzene; 1,6- di(alkylamino)hexane; and mixtures thereof; and / or wherein the chain extender is a secondary aromatic amine selected from the group consisting of N,N'-dialkylmethylenedianiline; N,N'-dialkylphenylenediamine; and mixtures thereof; and / or wherein the chain extender is a sterically hindered diamine.

5. The polyurea prepolymer of any preceding claim, wherein the secondary polymeric diamine is selected from the group consisting of a secondary aliphatic amine, a secondary aromatic amine, and mixtures thereof, preferably wherein the secondary polymeric diamine comprises a secondary aliphatic amine selected from the group consisting of N,N'-diisopropyl-polypropylene glycol diamine; and / or wherein the secondary polymeric diamine comprises a secondary aromatic amine.

6. The polyurea prepolymer of any preceding claim, wherein the reaction mixture comprises: i. between about 25 wt% and between about 90 wt% of MDI;ii. between about 0 wt% and about 20 wt % secondary diamine chain extender; and iii. between about 0 and about 75 wt% secondary polymeric diamine based on the total weight of the reaction mixture, provided that the polyurea prepolymer comprises at least one of component ii) or iii).

7. A polyurea-polyurethane hybrid prepared by reacting the polyurea prepolymer described in any one of claims 1 to 6 and a resin blend comprising at least one polyol and optionally at least one polyamine and / or diamine.

8. The polyurea-polyurethane hybrid of claim 7, wherein the polyol is a polyester polyol, a polyether polyol, a polycarbonate polyol, or a mixture thereof.

9. The polyurea-polyurethane hybrid of claim 7 or claim 8, wherein polyamine is a polymeric secondary diamine, a secondary amine chain extender, or a mixture thereof.

10. The polyurea-polyurethane hybrid of any one of claims 7 to 9, wherein the resin blend further comprises at least one component selected from one or more defoamers, one or more moisture scavengers, castor oil, one or more pigments, and one or more plasticizers.

11. The polyurea-polyurethane hybrid of any one of claims 7 to 10, wherein a mixture of the prepolymer and the resin blend has a pot life greater than 40 min at 25 °C.

12. A method for preparing a polyurea-polyurethane hybrid polymer said comprising mixing a polyurea prepolymer as described in any one of claims 1 to 6 and a resin composition as described in any one of claims 7 to 11 and curing at ambient temperature and pressure.

13. The method of claim 12, wherein the polymer cures in a time greater than 40 min at ambient temperature and pressure; and / or wherein the polymer touch dry time is less than or equal to 5 hours; and / or wherein the polymer tack free time is less than or equal to 24 hours.

14. A polyurea-polyurethane hybrid polymer prepared by the method of claim 12 or claim 13.

15. The polyurea-polyurethane hybrid polymer of claim 14, wherein the polyurea is spray coated or hand coated onto a surface.

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