Rapid preparation of polyaspartic acid esters containing low primary amines and use of these polyaspartic acid esters in slow-reacting polyurea systems

Abstract

The present invention provides a low primary amine (LPA) polyaspartic acid ester, which comprises an aliphatic diamine and an excess of a Michael addition acceptor, optionally at C1-C 10 The invention relates to a reaction product in the presence of an alcohol, wherein the low primary amine (LPA) polyaspartic acid ester has a monoaspartic acid ester content of less than 10%. The low primary amine (LPA) polyaspartic acid ester of the present invention can be used in a slow-reacting polyurea system and react with a polyisocyanate to produce polyurea coatings, adhesives, sealants, films, composite materials, casting materials and paints.

Description

Field of the Invention

[0001] The present invention relates generally to coatings and, more particularly, to the rapid preparation of low primary amine (LPA) containing polyaspartic esters and the use of these polyaspartic esters in slow reacting polyurea systems. Background of the Invention

[0003] Two-component coating systems based on polyurethane or based on polyurea are known to those skilled in the art. Typically, such systems comprise a liquid polyisocyanate component and a liquid isocyanate-reactive component. Polyisocyanates react with amines as isocyanate-reactive components to produce highly crosslinked polyurea coatings. However, primary amines and isocyanate moieties typically react very quickly with each other, with typical pot life or gel time typically being only seconds to minutes. Primary amines present in standard polyaspartic amines react quickly with polyisocyanates, generating heat and accelerating the reaction, which may shorten the pot life of the resin and increase its viscosity. The problem of rapid reactivity of polyaspartic amines may be further exacerbated by carrying out the reaction in a high humidity and high temperature environment. As a result, the operating time is reduced, which may lead to application problems for contractors applying coatings under higher humidity / higher temperature conditions.

[0004] Various approaches have been attempted to mitigate these problems. For example, Karl et al. in WO 2018 / 160932 provide a method for preparing a polyaspartic acid ester composition, the method comprising reacting a primary diamine reactant composition with a diester reactant composition under conditions to prepare a polyaspartic acid ester composition having a primary amine value of less than 35 mg KOH / g, wherein, during the reaction, the combined water content of the primary diamine reactant composition and the diester reactant composition is less than 300 ppm. In paragraph

[0022] , Karl et al. state that the combined water content of the primary diamine reactant composition and the diester reactant composition is less than 200 ppm, or less than 100 ppm, or less than 75 ppm, or less than 50 ppm, or less than 25 ppm.

[0005] Therefore, there is a need in the art for a rapid process for preparing low primary amine-containing polyaspartic acid esters for use in slow-reacting polyurea systems. SUMMARY OF THE INVENTION

[0007] Thus, the present invention reduces or eliminates the problems inherent in the art by providing a rapid process for preparing low primary amine containing polyaspartic acid esters having higher water contents than those in the art. Such low primary amine containing polyaspartic acid esters can be used in slow reacting polyurea systems.

[0008] These and other advantages and benefits of the present invention will become apparent from the following detailed description of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The present invention will now be described for purposes of illustration and not limitation with reference to the accompanying drawings, in which:

[0011] Figure 1 The percentage of monoaspartate (monoaspartate amine), diaspartate (diaspartate amine), high molecular weight amide, and diaspartate-EtOH ("diaspartate minus ethanol") in the reaction product of diamine A with 50% excess diethyl maleate (DEM) is shown as a function of time measured in weeks;

[0012] Figure 2 The percentages of monoaspartate, diaspartate, high molecular weight amide, and diaspartate-EtOH in the reaction product of diamine B with 50% excess DEM are shown as a function of time measured in weeks;

[0013] Figure 3 The percentages of monoaspartate, diaspartate, high molecular weight amide, and diaspartate-EtOH in the reaction products of diamine A with an equal amount of ethanol and a 50% excess of DEM are depicted over an eight-week period;

[0014] Figure 4 The percentages of monoaspartate, diaspartate, high molecular weight amide, and diaspartate-EtOH in the reaction product of diamine B with an equal amount of ethanol and a 50% excess of DEM are shown over a period of eight weeks;

[0015] Figure 5 Depicted are the percentages of diamine A, high molecular weight amide, diaspartate-EtOH, monoaspartate, and diaspartate over a seven-day period following the synthesis of LPA aspartate A using ethanol and excess DEM;

[0016] Figure 6 It is shown that after distilling off ethanol and DEM, thin film evaporated LPA aspartate A retains a low percentage of monoaspartate;

[0017] Figure 7 Shown is a comparison of the exothermicity of aspartate A and LPA aspartate A prepared according to the present invention;

[0018] Figure 8 Shows Figure 7 An enlarged view of a portion of the exotherm comparison within the first 10 minutes of the reaction;

[0019] Fig. 9The viscosity change over time of a 50 / 50 blend of LPA aspartate A and LPA aspartate B reacted with polyisocyanate A relative to a control (50 / 50 blend of aspartate A and aspartate B) reacted with polyisocyanate A is shown;

[0020] Fig.10 The exotherm of a 50 / 50 blend of LPA aspartate A and LPA aspartate B reacting with polyisocyanate A relative to a control (50 / 50 blend of aspartate A and aspartate B) reacting with polyisocyanate A is shown;

[0021] Fig.11 The diaspartate content of the aspartate A variant aged at room temperature over a period of eleven days is shown;

[0022] Fig.12 Shown is the monoaspartate content of the aspartate A variant aged at room temperature over a period of eleven days;

[0023] Fig.13 Depicted is the diaspartate-EtOH content of the aspartate A variant aged at room temperature over eleven days;

[0024] Fig.14 Shown is the high molecular weight amide content of the aspartate A variant aged at room temperature over a period of eleven days;

[0025] Fig.15 depicts the rate of formation of the diaspartate ester of the aspartate A variant; and

[0026] Fig.16 The rate of decrease of the monoaspartate content is shown. DETAILED DESCRIPTION OF THE INVENTION

[0028] The present invention will now be described for purposes of illustration and not limitation.Except in the operating examples, or where otherwise indicated, all numbers expressing amounts, percentages, and the like in the specification are to be understood as being modified in all instances by the term "about".

[0029] Any numerical range described in this specification is intended to include all sub-ranges of the same numerical precision contained in the range. For example, the range of "1.0 to 10.0" is intended to include all sub-ranges between the described minimum value 1.0 and the described maximum value 10.0 (and including the described minimum value and the described maximum value), that is, all sub-ranges with a minimum value equal to or greater than 1.0 and a maximum value equal to or less than 10.0, for example, 2.4 to 7.6. Any maximum numerical limit described in this specification is intended to include all lower numerical limits contained therein, and any minimum numerical limit described in this specification is intended to include all higher numerical limits contained therein. Therefore, the applicant reserves the right to modify this specification (including claims) to explicitly describe any sub-range contained in the scope explicitly described herein. All such ranges are intended to be inherently described in this specification so that the modification of any such sub-range explicitly described will meet the requirements of 35 USC § 112 (a) and 35 USC § 132 (a). The various embodiments disclosed and described in this specification may comprise, consist of, or consist essentially of the features and characteristics as variously described herein.

[0030] Unless otherwise stated, any patent, publication or other public material identified herein is incorporated by reference in its entirety into this specification, but only to the extent that the incorporated material does not conflict with existing definitions, statements or other public materials explicitly set forth in this specification. Therefore, and to the extent necessary, the explicit disclosure set forth in this specification supersedes any conflicting material incorporated by reference herein. Any material or portion thereof that is said to be incorporated by reference into this specification, but conflicts with existing definitions, statements or other public materials set forth herein, is incorporated only to the extent that no conflict occurs between the incorporated material and the existing public materials. Applicants reserve the right to amend this specification to explicitly state any subject matter or portion thereof incorporated herein by reference.

[0031] References throughout this specification to "various non-limiting embodiments," "certain embodiments," etc. mean that particular features or characteristics may be included in the embodiments. Therefore, the use of phrases "in various non-limiting embodiments," "certain embodiments," etc. in this specification does not necessarily refer to a common embodiment, and may refer to different embodiments. In addition, particular features or characteristics may be combined in one or more embodiments in any suitable manner. Therefore, particular features or characteristics illustrated or described in conjunction with various or certain embodiments may be combined in whole or in part with features or characteristics of one or more other embodiments without limitation. Such modifications and variations are intended to be included within the scope of this specification.

[0032] Unless otherwise indicated, the grammatical articles "a", "an", and "the" as used herein are intended to include "at least one" or "one or more", even if "at least one" or "one or more" is explicitly used in some cases. Therefore, these articles are used in this specification to refer to one or more than one or more than one (i.e., "at least one") of the grammatical objects of the article. As an example and not limitation, "a component" means one or more components, and therefore, more than one component may be expected and may be employed or used in the implementation of the described embodiments. In addition, the use of a singular noun includes the plural, and the use of a plural noun includes the singular, unless the context of the usage requires otherwise.

[0033] In a first aspect, the present invention relates to low primary amine (LPA) polyaspartic acid esters comprising an aliphatic diamine and an excess of a Michael addition acceptor, optionally at C1-C 10 The reaction product in the presence of an alcohol, wherein the low primary amine (LPA) polyaspartate has a monoaspartate content of less than 10%.

[0034] In another aspect, the present invention relates to a method for producing low primary amine (LPA) polyaspartic acid esters, comprising reacting an aliphatic diamine with an excess of a Michael addition acceptor, optionally at a C1-C 10 The method comprises reacting the low primary amine (LPA) polyaspartic acid ester in the presence of an alcohol, wherein the low primary amine (LPA) polyaspartic acid ester has a monoaspartic acid ester content of less than 10%.

[0035] In yet another aspect, the present invention relates to coatings, adhesives, sealants, films, composites, castings and paints comprising the low primary amine (LPA) polyaspartic acid ester according to the present invention.

[0036] In yet another aspect, the present invention is directed to a polyurea comprising the reaction product of a polyisocyanate and a low primary amine (LPA) polyaspartic acid ester according to the present invention.

[0037] As used herein, the terms "coating composition" and "coating" refer to a mixture of chemical components that, when applied to a substrate, optionally cures and forms a coating.

[0038] The terms "adhesive" and "adhesive compound" refer to any substance that can adhere or bond two items together. Implicit in the definitions of "adhesive composition" and "adhesive formulation" is the concept that a composition or formulation is a combination or mixture of more than one species, component or compound, which may include adhesive monomers, oligomers and polymers as well as other materials.

[0039] "Sealant composition" and "sealant" refer to a composition that can be applied to one or more surfaces to form a protective barrier, for example to prevent the ingress or egress of solid, liquid or gaseous materials, or alternatively to allow selective permeation of gases and liquids through the barrier. In particular, it can provide a seal between surfaces.

[0040] "Foundry material composition" and "casting material" refer to a mixture of liquid chemical components that is typically poured into a mold containing a hollow cavity of a desired shape and then allowed to solidify.

[0041] A "composite material" or "composite composition" refers to a material made from one or more polymers that contains at least one other type of material (e.g., fiber) that retains its identity while providing the composite with desirable properties. A composite material has properties that are different from those of the individual polymers / materials that make it up.

[0042] As used herein, the term "lacquer" refers to a substance used to decorate or protect surfaces and is typically a mixture containing solid pigments suspended in a liquid which, when applied to a surface, dries to form a hard, protective coating.

[0043] "Cured", "cured composition" or "cured compound" refers to components and mixtures obtained from reactive curable original compound(s) or mixture(s) thereof, which have undergone chemical and / or physical changes such that the original compound(s) or mixture(s) are transformed into a solid, substantially non-flowing material. Typical curing processes may involve cross-linking.

[0044] The term "curable" means that the original compound(s) or composition material(s) can be converted into a solid, substantially non-flowing material by chemical reaction, cross-linking, radiation cross-linking, etc. Thus, the compositions of the present invention are curable, but unless otherwise specified, the original compound(s) or composition material(s) are uncured.

[0045] As used herein, "polymer" includes prepolymers, oligomers, and homopolymers and copolymers; the prefix "poly" herein means two or more.

[0046]

[0043] As used herein, "molecular weight" when referring to a polymer, unless otherwise indicated, means the number average molecular weight ("Mn").

[0047] As used herein, the M of a polymer containing a functional group (such as a polyol) is n It can be calculated from the number of functional groups (eg, hydroxyl number) determined by end group analysis.

[0048] As used herein, the term "aliphatic" refers to organic compounds characterized by substituted or unsubstituted straight, branched and / or cyclic chain arrangements of constituent carbon atoms. Aliphatic compounds do not contain aromatic rings as part of their molecular structure.

[0049] As used herein, the term "alicyclic" refers to an organic compound characterized by the arrangement of carbon atoms in a closed ring structure. Alicyclic compounds do not contain aromatic rings as part of their molecular structure. Therefore, alicyclic compounds are a subset of aliphatic compounds. Therefore, the term "aliphatic" includes aliphatic compounds and alicyclic compounds.

[0050] As used herein, "diisocyanate" refers to a compound containing two isocyanate groups. As used herein, "polyisocyanate" refers to a compound containing two or more isocyanate groups. Therefore, diisocyanates are a subset of polyisocyanates.

[0051] As known to those skilled in the art, polyaspartic acid esters can be produced by reacting linear or branched alkyl or cycloalkyl residues of polyamines with Michael addition acceptors, i.e., electron withdrawing groups such as cyano, keto or ester (electrophiles) in Michael addition reactions. The low primary amine (LPA) polyaspartic acid esters of the present invention comprise an aliphatic diamine with at least 50% excess of a Michael addition acceptor, optionally in the range of C1-C 10 The reaction product in the presence of an alcohol. Preferred alcohols are alkyl alcohols, such as methanol, ethanol and propanol, with ethanol being particularly preferred.

[0052] Examples of suitable Michael addition acceptors include, but are not limited to, acrylates and diesters such as dimethyl maleate, diethyl maleate, dibutyl maleate, dimethyl fumarate, diethyl fumarate, and dibutyl fumarate.

[0053] The polyamine may be an aliphatic or alicyclic diamine. Examples of suitable alicyclic diamines include, but are not limited to, isophorone diamine (5-amino-(1-aminomethyl)-1,3,3-trimethylcyclohexane); 1,3-cyclohexane bis(methylamine) (1,3-BAMC); 1,4-cyclohexane bis(methylamine) (1,4-BAMC); 4,4'-diaminodicyclohexylmethane (PACM 20); bis(4-amino-3-methylcyclohexyl)methane; 3,3'-dimethyl-4,4'-diaminodicyclohexyl-methane (DMDC); isomers thereof; salts thereof; complexes thereof; adducts thereof; and any mixtures thereof.

[0054] In various embodiments, the production of the low primary amine (LPA) polyaspartic acid esters of the present invention from aliphatic diamines and an excess of Michael addition acceptor starting materials can be carried out at a temperature range of 0°C to 100°C, and in certain embodiments, at a temperature range of 10°C, or 20°C, or 30°C, or 50°C, or 60°C to 70°C, or 80°C, or 90°C. The amount of starting materials used is such that the Michael addition acceptor is in excess relative to the aliphatic diamine. In various embodiments, the excess can be at least 10%, or at least 20%, or at least 30%, or at least 40%, or at least 50%, or more.

[0055] A reaction scheme of one embodiment of the present invention using the alicyclic diamine 4,4'-diaminodicyclohexylmethane (PACM 20) and the Michael addition acceptor diethyl maleate (DEM) is shown below.

[0056]

[0057]

[0058]

[0059] The present inventors have observed that, in certain circumstances, the monoaspartate reaction product (I) and the diaspartate reaction product (II) can combine to form higher molecular weight amides (III), plus isomers.

[0060]

[0061] In other cases, the inventors postulate that the diaspartate reaction product may lose an ethanol molecule and form a lower molecular weight amide, one of the proposed structures being shown as (IV). This amidization represents an intramolecular cyclization.

[0062]

[0063]

[0064] Unexpectedly, the present inventors have discovered that the use of excess diethyl maleate produces low primary amine (LPA) polyaspartates having lower monoaspartate levels than conventionally produced polyaspartates, and further discovered that C1-C 10The addition of alcohol (in various embodiments, methanol, ethanol, propanol) favors the production of diaspartate reaction products (II) over monoaspartate (I). Thus, in various embodiments, the low primary amine (LPA) polyaspartate of the present invention has a monoaspartate content of less than 10%, less than 5% in certain embodiments, and less than 3% in selected embodiments. Polyurea coatings, adhesives, sealants, films, composites, casting materials and paints can be produced from the low primary amine (LPA) polyaspartate according to the present invention by reacting with polyisocyanates.

[0065] Suitable polyisocyanates useful in various embodiments of the present invention include organic diisocyanates represented by the formula

[0066] R(NCO)2

[0067] wherein R represents an organic group obtained by removing an isocyanate group from an organic diisocyanate having an ali(cyclo)phatic bonded isocyanate group and a molecular weight of 112 to 1,000, preferably 140 to 400. Preferred diisocyanates of the present invention are those represented by the formula wherein R represents a divalent aliphatic hydrocarbon group having 4 to 18 carbon atoms, a divalent alicyclic hydrocarbon group having 5 to 15 carbon atoms, or a divalent aromatic aliphatic hydrocarbon group having 7 to 15 carbon atoms.

[0068] Examples of organic diisocyanates particularly suitable for use in the present invention include 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate (HDI), 2,2,4-trimethyl-1,6-hexamethylene diisocyanate, 1,12-dodecamethylene diisocyanate, cyclohexane-1,3- and 1,4-diisocyanate, 1-isocyanato-2-isocyanato-methylcyclopentane, 1-isocyanato-3-isocyanatomethyl-3,5,5-trimethylcyclohexane (isophorone diisocyanate or IPDI), bis-(4-isocyanatocyclohexyl)-1,3- and 1,4-diisocyanate. )methane, 1,3- and 1,4-bis(isocyanatomethyl)-cyclohexane, bis-(4-isocyanato-3-methyl-cyclohexyl)-methane, α,α,α',α'-tetramethyl-1,3- and 1,4-xylylene diisocyanate, 1-isocyanato-1-methyl-4(3)-isocyanato-methylcyclohexane, and 2,4- and 2,6-hexahydrotoluene diisocyanate, toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), pentane diisocyanate (PDI)-bio-based, and isomers or combinations of any of these. Mixtures of diisocyanates may also be used. Particularly preferred diisocyanates include 1,6-hexamethylene diisocyanate, isophorone diisocyanate, and bis(4-isocyanatocyclohexyl)-methane because they are readily available and produce relatively low viscosity oligomers.

[0069] The coatings, adhesives, sealants, films, composites, casting materials and paints of the present invention may further comprise any of a variety of additives known to those skilled in the art, such as defoamers, devolatilizers, thickeners, flow control additives, colorants (including pigments and dyes), surfactants, dispersants and neutralizers.

[0070] The coating materials and lacquers of the invention can be mixed and combined with binders, auxiliaries and additives of conventional lacquer technology selected from the group consisting of pigments, dyes, matting agents, flow control additives, wetting additives, slip additives, pigments including metallic effect pigments, fillers, nanoparticles, light-stabilizing particles, anti-yellowing additives, thickeners and additives for reducing surface tension.

[0071] Low primary amine (LPA) polyaspartic acid esters can be used to produce polyurea coatings, adhesives, sealants, films, composites, casting materials and paints. Example

[0072] The following non-limiting and non-exhaustive examples are intended to further describe various non-limiting and non-exhaustive embodiments without limiting the scope of the embodiments described in this specification. Unless otherwise indicated, all amounts given in "parts" and "percentages" are understood to be by weight. Although described herein in the context of coatings, the present invention is not limited thereto. The principles of the present invention are equally applicable to coatings, adhesives, sealants, films, composite materials, casting materials and paints.

[0073] Diamine A 4,4'-diaminodicyclohexylmethane, commercially available as PACM 20 from Evonik Industries;

[0074] Diamine B 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane, commercially available as DMDC from BASF;

[0075] DEM diethyl maleate, commercially available from DSM;

[0076] EtOH ethanol, analytical grade, anhydrous;

[0077] Isocyanate A Aliphatic polyisocyanate resin based on hexamethylene diisocyanate, NCO content 23.5 ± 0.5%, viscosity 730 ± 100 mPa·s @ 23°C, commercially available as DESMODUR N-3900 from Covestro;

[0078] Aspartic A 100% solids aspartic acid ester functional amine, amine value ~201 mg KOH / g, viscosity @25°C 1450 mPa·s;

[0079] Aspartic Acid B 100% solids aspartic acid ester functional amine, amine value of about 191 mg KOH / g, viscosity @ 25°C is 1400;

[0080] LPA Aspartate A A low primary amine variant of a proprietary Aspartate A prepared according to the present invention, having a water content of 0.021% (+ / - 0.02) after stripping of EtOH and DEM;

[0081] LPA Aspartate B A low primary amine variant of a proprietary Aspartate B prepared according to the present invention, having a water content of 0.028% (+ / - 0.03) after stripping of EtOH and DEM;

[0082] TBA tert-butyl acetate; and

[0083] Additive A A flow promoter and deaerator, commercially available as BORCHI GOL 0011 from OMG Americas, Inc.

[0084] Referring to Table I, Example A; Diamine A was reacted with 50% excess DEM to produce a low primary amine (LPA) polyaspartate. The composition of Example A exhibits an increase in diaspartate-EtOH ("diaspartate minus ethanol").

[0085] In Example B, diamine A is reacted with a 50% excess of DEM and ethanol to produce a low primary amine (LPA) polyaspartate. The composition of Example B does not show an increase in high molecular weight amides.

[0086] In Example C, diamine B is reacted with a 50% excess of DEM to produce polyaspartate. The composition of Example C shows an increase in diaspartate-EtOH.

[0087] In Example D, diamine B is reacted with 50% excess DEM and ethanol to produce a low primary amine (LPA) polyaspartate. The composition of Example D does not show an increase in high molecular weight amides.

[0088] Table I

[0089] Ex. A Ex. B Ex. C Ex. D Diamine A 227.55g 227.55g Diamine B 368.01g 368.01g DEM 558.67g 558.67g 797.98g 797.98g EtOH 227.55g 368.01g

[0090] Figure 1 The percentage of monoaspartate, diaspartate and diaspartate-EtOH as determined by LC-MS (liquid chromatography-mass spectrometry) in the reaction product of diamine A with 50% excess DEM is shown over time measured in weeks (Ex. A). Figure 1 Aspartate A was included as a control for weeks 7 and 8. Figure 1 As can be appreciated, excess DEM produces a reaction product with less monoaspartate but more diaspartate-EtOH.

[0091] Figure 2 The percentages of monoaspartate, diaspartate, and diaspartate-EtOH in the reaction product of diamine B with 50% excess DEM are shown as a function of time measured in weeks (Ex. C). Figure 2 Aspartate B was included as a control for weeks 7 and 8. Figure 2 As can be appreciated, the resulting reaction product has more diaspartate-EtOH, undergoes a slower reaction and formation of diaspartate-EtOH, and has a similar monoaspartate content compared to the control.

[0092] Figure 3 The percentage of monoaspartate, diaspartate, and diaspartate-EtOH in the reaction product of diamine A with 50% excess DEM + EtOH is depicted over an eight-week period (Ex. B). Figure 3 Aspartate A was included as a control for weeks 7 and 8. Figure 3 As can be appreciated, the reaction was completed within the first week, although the formation of diaspartate-EtOH continued over time and the monoaspartate content of Ex. B was lower than that of the control.

[0093] Figure 4 The percentage of monoaspartate, diaspartate, and diaspartate-EtOH in the reaction product of diamine B with 50% excess DEM + EtOH is shown over an eight week period (Ex. D). Figure 4 Aspartate B was included as a control for weeks 7 and 8. Figure 4 It can be understood that the reaction was completed between the first and third weeks and the formation of diaspartate-EtOH occurred over time. The monoaspartate content was lower than that of the control.

[0094] Figure 5 The synthesis of LPA aspartate A with EtOH and excess DEM is depicted over a seven day period as the percentage of diamine, amide, monoaspartate, diaspartate-EtOH, and diaspartate. Figure 6 It was shown that thin film evaporated LPA aspartate A retained a low percentage of monoaspartate after stripping off EtOH and DEM.

[0095] Figure 7Shown is a comparison of the exotherms of Aspartate A and LPA Aspartate A prepared according to the present invention. Isocyanate A (8.2 g) was reacted with Aspartate A (11.8 g) or LPA Aspartate A (11.8 g) and the exotherm was measured using a J-KEM Scientific temperature controller and temperature probe. Figure 8 Shows Figure 7 The exotherm is compared between 0°C and 6°C. Figure 7 and Figure 8 As can be understood, the primary amine in aspartate A reacts immediately, producing a temperature spike.

[0096] Fig. 9 The viscosity of a 50 / 50 blend of LPA aspartate A and LPA aspartate B relative to a control (a 50 / 50 blend of aspartate A and aspartate B) over time is shown (see Table II). The viscosity was measured using a Brookfield viscometer. Fig. 9 As can be appreciated, removal of the primary amine slows molecular weight growth as measured by viscosity.

[0097] Table II

[0098] Element Amount (g) Amount (g) Aspartate A 49.28 Aspartate B 49.28 LPA A 49.28 LPA B 49.28 Additive A 1.721 1.721 TBA 8.619 8.619 Isocyanate A 66.1 66.1

[0099] Fig.10 The exotherm of a 50 / 50 blend of LPA Aspartate A and LPA Aspartate B relative to a control (a 50 / 50 blend of Aspartate A and Aspartate B) is shown (see Table II), as measured by a J-KEM Scientific temperature controller and temperature probe. Fig.10 As can be appreciated, removal of the primary amine reduces the exotherm.

[0100] Fig.11 Shown is room temperature aging of aspartate - aspartate A variant - diaspartate over an 11 day period. Fig.12 Shown is room temperature aging of aspartate - Aspartate A variant - monoaspartate over an 11 day period. Fig.13 Depicted is room temperature aging of aspartate-aspartate A variant-diaspartate-EtOH over 11 days. Fig.14 Shown is room temperature aging of Aspartate - Aspartate A variant - Diaspartate - EtOH + Monoaspartate over 11 days. Fig.15 The diaspartate rate (% diaspartate vs. time in days) is depicted, and Fig.16 Monoaspartate rates (% monoaspartate vs. time in days) are shown.

[0101] The inventors performed titrations to determine the amount (in mg KOH / g) and percentage of primary amines in each of Aspartate A, LPA Aspartate A, and Diamine A. As can be appreciated by reference to Table III, LPA Aspartate A has a significantly lower percentage of primary amines than Aspartate A. As expected, Diamine A is substantially all primary amines.

[0102] Table III

[0103] Material Primary amine (mg KOH / g) Primary amines (% of total amines) Aspartate A 18.05 9.06 LPA Aspartate A 7.24 3.86 Diamine A 7.81 98.99

[0104] As summarized in Table IV, a 50 / 50 blend of Aspartate A and Aspartate B reacted with Isocyanate A produced a material having a gel time of 143:51 minutes (measured by Gardco Standard Gel Timer, Paul N Gardner Company, Pompano Beach, FL USA). Addition of 1000 ppm of water reduced the gel time to 42:06 minutes.

[0105] Table IV

[0106] Ex. IV-1 Ex. IV-2 Ex. IV-3 Ex. IV-4 Component 1 Aspartate A 28.33 28.33 0 0 LPA Aspartate A 0 0 28.33 28.33 Aspartate B 28.33 28.33 0 0 LPA Aspartate B 0 0 28.33 28.33 TBA 5 5 5 5 water 0 0.1 0 0.1 Component 2 Isocyanate A 38.33 38.33 38.33 38.33 total 99.99 100.09 99.99 100.09 Gardner gel time (min) 143:51 42:06 195:03 67:42 ratio 3.41 2.893

[0107] Referring again to Table IV, a 50 / 50 blend of LPA Aspartate A and LPA Aspartate B produced a material having a gel time of 195:03 minutes (measured by Gardco Standard Gel Timer, Paul N Gardner Company, Pompano Beach, FL USA). Addition of 1000 ppm of water reduced the gel time to 67:42 minutes.

[0108] As can be understood by reference to Table IV, decreasing the percentage of primary amine in the polyaspartic acid ester increases the gel time (measured by Gardco Standard Gel Timer, Paul N Gardner Company, Pompano Beach, FL USA) and the addition of water catalyzes the reaction. The gel time ratios appear to be similar.

[0109] Work times and walk on times of commercial polyaspartic acid esters and their LPA variants were evaluated.Test floor coating formulations were prepared by combining the ingredients in the amounts listed in Table V.

[0110] Table V

[0111] Ex. V-1 Ex. V-2 Component 1 Aspartate A 33.79 0 LPA Aspartate A 0 33.79 Aspartate B 33.79 0 LPA Aspartate B 0 33.79 TBA 5.91 5.91 Additive A 1.18 1.18 Component 2 Isocyanate A 45.32 45.32

[0112] The formulation illustrated by Example V-1 using commercially available polyaspartic acid esters has an operating time of about ten minutes. Evaluate the open walking time, and at five hours, the boot marks formed on the coating surface disappear, and at six hours, no boot marks are formed. Evaluate the operating time by applying the formulation to the pre-prepared MASONITE board with a roller. Apply a strip of about 12.7 cm (5 inches) wide and 0.203 mm (8 mils) thick. Every five minutes, apply another 12.7 cm (5 inches) strip overlapping two coating edges. When the wet edges are no longer blended together (as observed after curing), the end of the operating time is reached. Or more succinctly, when the overlap line reflow stops and is manifested as a line in the cured coating, the operating time has been exceeded. The open walking time is tested by applying a coating of 0.203 mm (8 mils) to the MASONITE board. 91 KG (200 pounds) of individuals step on the board at intervals. Each step is on the untested coating part. Open walk time is reached when no marks or indentations are left on the coating after curing.

[0113] By comparison, the low primary amine (LPA) polyaspartic acid ester formulation, Example V-2, had an open time of approximately 17.5 minutes. As for the open walk-on time of the LPA formulation, at five hours, slight boot marks could be formed on the surface, while at six hours, no marks were formed.

[0114] Thus, using the low primary amine (LPA) polyaspartic ester formulation, the open time nearly doubled while the open walk-through time remained essentially the same – providing contractors with longer open time without sacrificing productivity.

[0115] This specification is written with reference to various non-limiting and non-exhaustive embodiments. However, it will be appreciated by those of ordinary skill in the art that various replacements, modifications or combinations may be made to any disclosed embodiment (or part thereof) within the scope of this specification. Therefore, it is contemplated and understood that this specification supports other embodiments that are not explicitly set forth herein. For example, such embodiments may be obtained by combining, modifying or reorganizing any disclosed steps, components, elements, features, aspects, characteristics, limitations, etc. of the various non-limiting embodiments described in this specification. In this way, the applicant reserves the right to modify the claims during the examination to increase the features variously described in this specification, and such modifications meet the requirements of 35 USC §112(a) and 35 USC §132(a).

Claims

1. A low primary amine (LPA) polyaspartic acid ester comprising the reaction product of an aliphatic diamine and an excess of a Michael addition acceptor in the presence of ethanol, wherein the Michael addition acceptor is included in an excess of at least 50%, wherein the low primary amine (LPA) polyaspartate has a monoaspartate content of less than 10%, and wherein the Michael addition acceptor is selected from dimethyl maleate, diethyl maleate, dibutyl maleate, dimethyl fumarate, diethyl fumarate, dibutyl fumarate, acrylates, and combinations thereof.

2. The low primary amine (LPA) polyaspartic acid ester according to claim 1, wherein the aliphatic diamine is a cycloaliphatic diamine.

3. The low primary amine (LPA) polyaspartic acid ester according to claim 2, wherein the alicyclic diamine is selected from isophoronediamine (5-amino-(1-aminomethyl)-1,3,3-trimethylcyclohexane), 1,3-cyclohexanebis(methylamine), 1,4-cyclohexanebis(methylamine), 4,4'-diaminodicyclohexylmethane (PACM 20), bis(4-amino-3-methylcyclohexyl)methane, 3,3'-dimethyl-4,4'-diaminodicyclohexyl-methane (DMDC), isomers thereof, salts thereof, complexes thereof, adducts thereof, and any mixtures thereof.

4. The low primary amine (LPA) polyaspartic acid ester according to claim 1, wherein the monoaspartic acid ester content is less than 5%.

5. The low primary amine (LPA) polyaspartic acid ester according to claim 1, wherein the monoaspartic acid ester content is less than 3%.

6. One of a coating, an adhesive, a sealant, a film, a composite material, a casting material and a paint, comprising the low primary amine (LPA) polyaspartic acid ester according to claim 1.

7. A polyurea comprising the reaction product of a polyisocyanate and the low primary amine (LPA) polyaspartic acid ester according to claim 1.

8. The polyurea according to claim 7, wherein the polyisocyanate is selected from 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, 2,2,4-trimethyl-1,6-hexamethylene diisocyanate, 1,12-dodecamethylene diisocyanate, cyclohexane-1,3- and 1,4-diisocyanate, 1-isocyanato-2-isocyanato-methylcyclopentane, 1-isocyanato-3-isocyanatomethyl-3,5,5-trimethylcyclohexane (isophorone diisocyanate), bis-(4-isocyanato-methylcyclopentane) and cyclohexane-1,3- and 1,4-diisocyanate. The invention also includes 1,3- and 1,4-bis(isocyanatomethyl)-cyclohexane, bis-(4-isocyanato-3-methyl-cyclohexyl)-methane, α,α,α',α'-tetramethyl-1,3- and 1,4-xylylene diisocyanate, 1-isocyanato-1-methyl-4(3)-isocyanato-methylcyclohexane, and 2,4- and 2,6-hexahydrotoluene diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, pentane diisocyanate-bio-based, and isomers or combinations of any of these.

9. A method for producing polyurea, comprising reacting a polyisocyanate with the low primary amine (LPA) polyaspartic acid ester according to claim 1.

10. The method according to claim 9, wherein the polyisocyanate is selected from 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, 2,2,4-trimethyl-1,6-hexamethylene diisocyanate, 1,12-dodecamethylene diisocyanate, cyclohexane-1,3- and 1,4-diisocyanate, 1-isocyanato-2-isocyanato-methylcyclopentane, 1-isocyanato-3-isocyanatomethyl-3,5,5-trimethylcyclohexane (isophorone diisocyanate), bis-(4-isocyanato-methylcyclopentane) and cyclohexane-1,3- and 1,4-diisocyanate. The invention also includes 1,3- and 1,4-bis(isocyanatomethyl)-cyclohexane, bis-(4-isocyanato-3-methyl-cyclohexyl)-methane, α,α,α',α'-tetramethyl-1,3- and 1,4-xylylene diisocyanate, 1-isocyanato-1-methyl-4(3)-isocyanato-methylcyclohexane, and 2,4- and 2,6-hexahydrotoluene diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, pentane diisocyanate-bio-based, and isomers or combinations of any of these.

11. A method for producing low primary amine (LPA) polyaspartic acid esters comprising reacting an aliphatic diamine with an excess of a Michael addition acceptor in the presence of ethanol, wherein the Michael addition acceptor is included in an excess of at least 50%, wherein the low primary amine (LPA) polyaspartate has a monoaspartate content of less than 10%, and wherein the Michael addition acceptor is selected from dimethyl maleate, diethyl maleate, dibutyl maleate, dimethyl fumarate, diethyl fumarate, dibutyl fumarate, acrylates, and combinations thereof.

12. The method of claim 11, wherein the aliphatic diamine is a cycloaliphatic diamine.

13. The method according to claim 12, wherein the alicyclic diamine is selected from isophoronediamine (5-amino-(1-aminomethyl)-1,3,3-trimethylcyclohexane), 1,3-cyclohexanebis(methylamine), 1,4-cyclohexanebis(methylamine), 4,4'-diaminodicyclohexylmethane (PACM 20), bis(4-amino-3-methylcyclohexyl)methane, 3,3'-dimethyl-4,4'-diaminodicyclohexyl-methane (DMDC), isomers thereof, salts thereof, complexes thereof, adducts thereof, and any mixtures thereof.

14. The method of claim 11, wherein the monoaspartate content is less than 5%.

15. The method of claim 11, wherein the monoaspartate content is less than 3%.

16. One of a coating, an adhesive, a sealant, a film, a composite material, a casting material and a paint, comprising the low primary amine (LPA) polyaspartic acid ester prepared according to the method of claim 11.

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