Continuous process for the production of aqueous polyurethane-polyurea dispersions

Abstract

The present invention relates to aqueous polyurethane-polyurea dispersions and a continuous process for producing such aqueous polyurethane-polyurea dispersions, which involves the use of a high shear dispersing device that includes a particular rotor / stator unit.

Description

[Technical Field]

[0001] The present invention relates to aqueous polyurea-polyurethane dispersions and also to a continuous method for producing aqueous polyurethane-polyurea dispersions. The dispersions have excellent applicability in coating compositions, particularly aqueous pigment coating compositions, and offer improved yellowing behavior. At the same time, the dispersions can be produced with very low organic solvent contents without the need for a step of removing such solvents by distillation. Furthermore, the polymer particles contained in the dispersions have very small particle sizes, resulting in excellent storage stability. [Background technology]

[0002] Aqueous dispersions of polyurethane and polyurethane-polyurea polymers are well known in the art. They are widely used in various industrial fields, such as the coatings industry. In particular, these polymers are used as binder resins in coating materials, which have a decisive influence on the properties and quality level of these materials.

[0003] The prior art describes versatile polyurethane and polyurethane-polyurea polymers and their applications, for example, in automotive basecoat materials, which require small particle sizes of dispersed polymer particles and optimal, stable dispersion properties.

[0004] For example, WO 2014 / 007915 A1 discloses a method for producing multi-coat automotive finishes using an aqueous basecoat material containing an aqueous dispersion of a polyurethane-polyurea resin produced by batch production, which can improve optical properties, particularly minimize gel spots.

[0005] WO 2016 / 091539 A1 describes a high-quality aqueous polyurethane-polyurea dispersion containing microgel particles and its preparation by a batch procedure. This dispersion is used as a binder resin in automotive basecoat compositions, contributing to improved properties such as pinhole and pop resistance. During the preparation of the dispersion, a relatively large amount of organic solvent must be added, ultimately leading to the need to distill off these to obtain aqueous dispersions with a low content of such organic solvents. WO 2016 / 091539 A1 also generally discloses a comprehensive list of alkali metal hydroxides as neutralizing agents, but only amine-based organic bases have been noted and applied in practice. The neutralizing agent is always added in the organic base phase, i.e., before, during, or directly after the preparation of the respective polyurethane prepolymer. The prepared basecoat composition can be improved in terms of its yellowing behavior (i.e., coatings such as multi-coat paint systems containing coating layers based on aqueous basecoat compositions tend to yellow continuously, ultimately leading to a decrease in optical quality).

[0006] In addition to batch production of individual polymers and dispersions, continuous production is gaining attention in polymer manufacturing, and it is clear that such continuous production offers substantial advantages over batch production, especially in industrial-scale production.

[0007] For example, DE 10 2004 017 436 A1 discloses a complex method for the continuous production of aqueous polyurethane dispersions by preparing an aqueous pre-emulsion by mixing a polyurethane prepolymer with water in a mixing nozzle and homogenizing the pre-emulsion so prepared in a multi-stage homogenizing nozzle.

[0008] EP 2157111 B1 discloses a method for producing aqueous polyurethaneurea resins by mixing a polyurethane prepolymer solution with water containing a low amount of organic solvent (ketone), whereby the prepolymer is prepared using an amine-neutralized polyhydroxycarboxylic acid, meaning that the prepolymer is already neutralized before being mixed with water. This feature allows the process to disperse the prepolymer with very small amounts of organic solvent, meaning that the resulting dispersion contains a similarly low content of such solvent without the need to distill off such solvent. This document generally states that the dispersion step can be carried out either batchwise or continuously via a rotor / stator unit, but the examples are exclusively of batch processes.

[0009] The advantages of continuous production of aqueous resin dispersions, especially on an industrial scale, are self-evident. However, one major challenge with continuous dispersion processes is the high difference in viscosity between the aqueous phase (essentially water) on the one hand and the polyurethane prepolymer solution (organic-based phase) on the other. Even if they are fed separately to the dispersion unit (i.e., in the form of separate material streams), the significantly higher viscosity of the organic phase compared to the aqueous phase remains a problem. While various known methods exist for reducing the viscosity of the organic phase, these methods have certain drawbacks. For example, increasing the polymer temperature implies high energy consumption and, more importantly, can lead to side reactions of isocyanate groups (the latter being particularly pronounced when commonly applicable neutralizing agents (tertiary amines) are already present at this stage). Increasing the amount of organic solvent in the organic phase naturally leads to a higher amount of organic solvent in the resulting aqueous dispersion (and, if a dispersion with low organic volatiles is desired, these organic solvents must ultimately be removed by distillation). [Prior art documents] [Patent documents]

[0010] [Patent Document 1] WO 2014 / 007915 A1 [Patent Document 2] WO 2016 / 091539 A1 [Patent Document 3] DE 10 2004 017 436 A1 [Patent Document 4] EP2157111 B1 Summary of the Invention [Problem to be solved by the invention]

[0011] From the above, it is clear that there is a need for aqueous polyurethane-polyurea dispersions that exhibit improved yellowing behavior and aqueous basecoat compositions containing such dispersions. It is also desirable to provide a continuous method for producing said aqueous polyurethane-polyurea dispersions, which at the same time provides optimal and stable dispersion properties of the dispersions by making it possible to produce dispersions with very low organic solvent contents. More particularly, these dispersions should be producible with such low organic solvent contents that the final respective distillation step of the organic solvent is omitted. [Means for solving the problem]

[0012] It has now been found that the above objects are achieved by novel aqueous polyurethane-polyurea dispersions and a continuous process for the preparation of aqueous polyurethane-polyurea dispersions.

[0013] More particularly, the novel aqueous polyurethane-polyurea dispersion comprises polyurethane-polyurea particles having a volume-based average diameter of 50 to 500 nm, the dispersion further characterized by an MEQ base of 0.125 to 0.625 meq / g (based on solids), whereby preparation of the dispersion includes a neutralization step using at least one alkali metal hydroxide as a neutralizing agent.

[0014] Also discovered is a novel method for continuously producing an aqueous polyurethane-polyurea dispersion comprising polyurethane-polyurea particles having a volume average diameter of from 50 to 500 nm, the dispersion further characterized by an MEQ base of from 0.125 to 0.625 meq / g (on a solids basis), the method comprising the steps of: (1) (a) at least one acid-functional polyurethane prepolymer containing isocyanate groups, and (b) 0 to 20% by weight of at least one organic solvent, based on the total weight of the organic-based phase (I); providing an organic-based phase (I) comprising (2) providing an aqueous phase (II); (3) continuously feeding both the organic-based phase (I) and the aqueous phase (II) into a high shear dispersing device comprising a rotor / stator unit; (3.1) the organic-based phase (I) and the aqueous phase (II) are brought into contact within the rotor / stator unit, rather than before reaching the rotor / stator unit; and (3.2) the organic phase (I) is fed to the rotor / stator unit via a plurality of inlets in the form of a plurality of sub-feed streams, (4) continuously dispersing the organic-based phase (I) and the aqueous phase (II) in a rotor-stator unit, thereby producing an aqueous polyurethane-based dispersion; (5) continuously discharging the aqueous polyurethane-based dispersion from the high shear disperser, thereby forming a volumetric flow of the dispersion; and (6) providing at least one chain extender to the aqueous polyurethane-based dispersion, thereby producing an aqueous polyurethane-polyurea dispersion. Including, A neutralization step with at least one alkali metal hydroxide as a neutralizing agent is carried out during the dispersion process according to steps (3) and (4) above. [Brief explanation of the drawings]

[0015] [Figure 1]FIG. 1 shows a stator (10) having three sets of stator tooth rows (11) with teeth (12). The first set of teeth (11) has the smallest diameter and consists of a total of 24 teeth spaced apart by, for example, 2.0 mm. The second set of teeth (11) has 34 teeth (1.2 mm apart), while the set of teeth (11) with the largest diameter has 160 teeth (0.3 mm). Also shown are the first and second inlets (13 and 14) arranged in a circle and spaced evenly apart from each other. In this figure, one half of the stator is shown in detail (i.e., the individual teeth (12) are visible and the individual second inlets (14) are also visible), while the other half is shown in schematic form (the tooth sets are circular and the individual second inlets are not). [Figure 2] Figure 2 shows a rotor (20) with four sets of rotor tooth rows (21) with teeth (22). The first set of teeth (21) has the smallest diameter and consists of a total of 12 teeth spaced apart by, for example, 3.0 mm. The second set of teeth (20) has 28 teeth (1.6 mm apart), and the third set of teeth (20) has 70 teeth (0.6 mm apart). The fourth set of teeth (20) has the largest diameter and consists of 160 teeth (0.3 mm apart). Again, half of the drawing is detailed and the other half is schematic. [Figure 3] FIG. 3 shows the rotor / stator unit as an overlap of FIGS. 1 and 2, thereby explicitly referencing the first inlet (13), two second inlets (14), three sets of stator teeth (11), and four sets of rotor teeth (21). Furthermore, the stator teeth and the three rotor teeth are identified according to their relative positions with respect to the second set of inlets. Thus, the rotor tooth row where the second inlet is located radially outward is designated rotor tooth row (21a), and each stator tooth row is designated stator tooth row (11a). Additionally, the rotor tooth row where the second inlet is located radially inward is designated rotor tooth row (21b), and each stator tooth row is designated stator tooth row (11b). DETAILED DESCRIPTION OF THE INVENTION

[0016] First, the novel method will be described.

[0017] In the first step (1) of the process of the present invention, an organic-based phase (I) is provided.

[0018] The organic-based phase (I) comprises at least one acid-functional polyurethane prepolymer (a) containing isocyanate groups.

[0019] Polyurethane polymers containing isocyanate groups and having acid functionality are known in principle. In the present invention, for ease of understanding, each component (a) is called a prepolymer. This component can be called a precursor, since it is actually a polymer (or oligomer) and is used as a starting component for preparing other components, in particular polyurethane-polyurea polymers in aqueous dispersion.

[0020] To prepare polyurethane prepolymers containing isocyanate groups and containing anionic groups and / or groups that can be converted into anionic groups, it is possible to use aliphatic, cycloaliphatic, aliphatic-cycloaliphatic, aromatic, aliphatic-aromatic and / or cycloaliphatic-aromatic polyisocyanates known to those skilled in the art. Diisocyanates are preferably used. By way of example, the following diisocyanates may be mentioned: 1,3- or 1,4-phenylene diisocyanate, 2,4- or 2,6-tolylene diisocyanate, 4,4'- or 2,4'-diphenylmethane diisocyanate, 1,4- or 1,5-naphthylene diisocyanate, diisocyanatodiphenyl ether, trimethylene diisocyanate, tetramethylene diisocyanate, ethylene diisocyanate, 2,3-dimethylethylene diisocyanate, 1-methyltrimethylene diisocyanate, pentamethylene diisocyanate, 1,3-cyclopentylene diisocyanate, hexamethylene diisocyanate, cyclohexylene diisocyanate, 1,2-cyclohexylene diisocyanate, octamethylene diisocyanate, trimethylhexane diisocyanate, tetramethylhexane diisocyanate, decamethylene diisocyanate. Anate, dodecamethylene diisocyanate, tetradecamethylene diisocyanate, isophorone diisocyanate (IPDI), 2-isocyanatopropylcyclohexyl isocyanate, dicyclohexylmethane 2,4'-diisocyanate, dicyclohexylmethane 4,4'-diisocyanate, 1,4- or 1,3-bis(isocyanatomethyl)cyclohexane, 1,4- or 1,3- or 1,2-diisocyanato Examples of suitable polyisocyanates include cyclohexane, 2,4- or 2,6-diisocyanato-1-methylcyclohexane, 1-isocyanatomethyl-5-isocyanato-1,3,3-trimethylcyclohexane, 2,3-bis(8-isocyanatooctyl)-4-octyl-5-hexylcyclohexene, tetramethylxylylene diisocyanates (TMXDI), such as m-tetramethylxylylene diisocyanate, or mixtures of these polyisocyanates. It is also possible to use different dimers and trimers of the aforementioned diisocyanates, such as uredione and isocyanurate.Polyisocyanates with higher isocyanate functionality can also be used. Examples include tris(4-isocyanatophenyl)methane, 1,3,4-triisocyanatobenzene, 2,4,6-triisocyanatotoluene, 1,3,5-tris(6-isocyanatohexylbiuret), and bis(2,5-diisocyanato-4-methylphenyl)methane. Functionality can be optionally reduced by reaction with monoalcohols and / or secondary amines. However, it is preferred to use diisocyanates, more particularly aliphatic diisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate (IPDI), dicyclohexylmethane 4,4'-diisocyanate, 2,4- or 2,6-diisocyanato-1-methylcyclohexane, and m-tetramethylxylylene diisocyanate (m-TMXDI). An isocyanate is called aliphatic if the isocyanate group is attached to an aliphatic group, in other words, there is no aromatic carbon in the alpha position to the isocyanate group.

[0021] Prepolymer (a) is prepared by reacting a polyisocyanate with a polyol, particularly a diol, to generally form a urethane.

[0022] Examples of polyols include the commonly known polyester, polycarbonate, polyether, polydiene, poly(meth)acrylate and / or polysiloxane polyols, more particularly diols. Mixtures of polyols are also possible.

[0023] Preferred examples of suitable polyols are saturated or olefinically unsaturated polyester polyols and / or polyether polyols. More particularly, the polyols used are polyester polyols, especially those having a number-average molecular weight of 400 to 5000 g / mol (see the Examples section for the measurement method). Such polyester polyols, preferably polyester diols, can be prepared in known manner by esterification of the corresponding polycarboxylic acids, preferably dicarboxylic acids, and / or their anhydrides with the corresponding polyols, preferably diols. Of course, it is also possible to use monocarboxylic acids and / or monoalcohols for the preparation, optionally and proportionally. The polyester diols are preferably saturated, more particularly saturated and linear.

[0024] Examples of aromatic polycarboxylic acids suitable for preparing such polyester polyols, preferably polyester diols, are phthalic acid, isophthalic acid, and terephthalic acid, of which isophthalic acid is preferred due to its advantages. Examples of suitable aliphatic polycarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, or hexahydrophthalic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 4-methylhexahydrophthalic acid, tricyclodecanedicarboxylic acid, and tetrahydrophthalic acid. It is also possible to use dimeric or dimerized fatty acids as dicarboxylic acids, which are mixtures prepared by dimerizing unsaturated fatty acids, as is well known, and are available, for example, under the trade names Radiacid (from Oleon) or Pripol (from Croda). In this specification, it is preferred to use such dimeric fatty acids to prepare polyester diols. Therefore, the polyols preferentially used in the preparation of prepolymer (a) are polyester diols prepared using dimeric fatty acids. Particularly preferred are polyester diols in which at least 50% by weight, preferably 55 to 75% by weight, of the dicarboxylic acids used in their preparation are dimeric fatty acids.

[0025] Examples of corresponding polyols for preparing polyester polyols, preferably polyester diols, are ethylene glycol, 1,2- or 1,3-propanediol, 1,2-, 1,3- or 1,4-butanediol, 1,2-, 1,3-, 1,4- or 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 2-methyl-2,4-pentanediol, 1,2-, 1,3-, 1,4-, 1,5- or 1,6-hexanediol, trimethylpentanediol, 1,2-, 1,3- or 1,4-cyclohexanediol, and difunctional alcohols which are α-, ω- or α-, β-dihydroxyalkanes having 8 to 25 carbon atoms, in particular 1,2-octanediol, 1,8-octanediol, 1,2-decanediol, 1,10-decanediol, 1,2-dodecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,2-octadecanediol, 1,18-octadecanediol, 1,2-henoicosanediol, 1,21-henoicosanediol, and 1,25-pentacosanediol. Further examples of corresponding polyols for preparing polyester polyols, preferably polyester diols, are polyols based on the hydrogenation products of methyl esters of polycarboxylic acids derived from dimeric and trimeric fatty acids, for example dimeric fatty C36 diol (Pripol® 2033 (from Croda)) after hydrogenation of the methyl ester of saturated dimeric C36 fatty acid.Further examples of corresponding polyols for preparing polyester polyols, preferably polyester diols, include ether or cyclic ether alcohols, such as diethylene glycol, triethylene glycol, tetraethylene glycol, 2,5-bis(hydroxymethyl)furan, 2,5-bis(hydroxymethyl)terahydrofuran, and carbohydrate-based cyclic ether alcohols, such as isosorbide, isomannide, isoimides, and ester alcohols, such as 3-hydroxy-2,2-dimethylpropyl-3-hydroxy-2,2-dimethylpropionate (neopentyl glycol mono(hydroxypivalate)).

[0026] Polyhydroxyalkyl acids such as poly(2-hydroxyethanoic acid) (polyglycolic acid) or polyhydroxypropionic acid (polylactic acid), also known as poly(lactic acid) (polylactide), and polyhydroxypolyesters derived from polyhydroxyalkyl acids with a higher carbon number can also be used. The direct method is based on the direct polycondensation of hydroxycarboxylic acids as α-, β-, γ-, or ω-hydroxy acids. Depending on the presence of hydroxyl and carbonyl groups, examples of the corresponding hydroxycarboxylic acids include 2-hydroxyethanoic acid (glycolic acid), 2-hydroxypropionic acid, 3-hydroxypropionic acid (lactic acid), 3-hydroxy-2-methylpropanoic acid, 3-hydroxybutanoic acid, 4-hydroxybutanoic acid, 3-hydroxypentanoic acid, 5-hydroxypentanoic acid, 12-hydroxydodecanoic acid (sabinic acid), and 13-hydroxytridecanoic acid. It is also possible and preferred to form polyester diols based on polyhydroxyalkyl acids by ring-opening polymerization of cyclic oligomers, preferably dimers, of the corresponding hydroxycarboxylic acids, e.g., by ring-opening polymerization of dilactides from the corresponding lactic acids to form poly(lactic acid), the best-known biodegradable polymer.

[0027] The term polyester diol can also be understood to mean polylactone diols obtained by reacting a polyol with a lactone as an initiator containing an active hydrogen group; examples include ethylene glycol, diethylene glycol, propanediol, 1,4-butanediol, 1,5-pentanediol, or 1,6-hexanediol, which are produced by ring-opening polymerization. Lactones that can be used to synthesize polyester polyols include butyrolactone, valerolactone, methylvalerolactone, caprolactone, methylcaprolactone, and 2-oxocanone (enantholactone). Preferred lactone polyols are known as polycaprolactone polyols.

[0028] Another example of suitable polyol is polycarbonate polyol, more particularly polycarbonate diol.These polycarbonate polyols can be prepared by reacting polyols such as 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2-methylpentane-1,3-diol, neopentyl glycol, 1,6-hexanediol, 2,2,4-trimethylpentane-1,3-diol, 2-butyl-3-ethylpropane-1,3-diol, trimethylolpropane or pentaerythritol, 1,4-bishydroxymethylcyclohexane, 2,2-bis(4-hydroxycyclohexyl)propane, diethylene glycol, triethylene glycol or tetraethylene glycol with dicarbonates such as dimethyl, diethyl or diphenyl carbonate or phosgene.

[0029] Further oligomeric or polymeric hydroxy-functional compounds are polydienes or polyenes having at least two, preferably terminal, hydroxyl groups per molecule. Particularly preferred are dihydroxy compounds based on polybutadiene, polyisoprene, or polyolefins, such as polyethylene (hydrogenated polybutadiene), and polybutadiene, polyisoprene, or polyolefin block copolymers with polystyrene.

[0030] Examples of polyether polyols here include polyoxyethylene, polyoxypropylene, polyoxybutylene, mixed and block copolymers thereof, either blockwise or randomly distributed along the polymer chain, and polyoxytetramethylene (polytetrahydrofuran, e.g., PolyTHF 2000 from BASF SE) polyols containing terminal OH groups, also known simply as glycols. Diols are also preferred here.

[0031] These polyols are conventional materials and are commercially available.

[0032] Suitable polyols are further exemplified by α,ω-dihydroxypoly(meth)acrylates (eg, TEGO® Diol MD 1000 from Evonik Tego Chemie GmbH) and α,ω-polydialkylsiloxanediols such as polydimethylsiloxanediol.

[0033] Diols are preferentially used. The polyols and / or diols mentioned above can of course also be used directly in the preparation of the prepolymer (a), that is to say, can be reacted directly with the polyisocyanate.

[0034] Further possibilities for use in preparing the prepolymer (a) are polyamines, such as diamines and / or aminoalcohols. Examples of diamines include hydrazine, alkyl- or cycloalkyldiamines, such as propylenediamine and 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane, and examples of aminoalcohols include ethanolamine or diethanolamine.

[0035] Prepolymer (a) is acid-functional (i.e., contains groups that can be converted to anionic groups by the use of known neutralizing agents). As those skilled in the art will recognize, these groups are, for example, carboxylic acid, sulfonic acid, and / or phosphonic acid groups, with carboxylic acid groups being particularly preferred. The introduction of such groups is known to enhance dispersibility in water. Depending on the selected conditions, the described groups can be present proportionally or almost entirely in one form (e.g., carboxylic acid) or the other form (carboxylate salt). Of particular influence is the use of a neutralizing agent, which will be discussed in more detail below. When prepolymer (a) is mixed with such a neutralizing agent, the amount of acid groups undergoes a corresponding base conversion, which corresponds to the amount of neutralizing agent. For example, if a polymer has a certain amount of carboxylic acid groups, some or all of them may be converted to carboxylate groups (corresponding bases) by such a neutralizing agent. The amount of carboxylic acid groups can be expressed by the acid number (determined as described in the Examples) or MEQ acid (the molar amount of acid groups [mmol] per mass [g] of polymer). The amount of (corresponding) basic groups, e.g., carboxylate groups, can be expressed as MEQ base (i.e., molar amount of basic groups [mmol] per mass [g] of polymer), which can be determined experimentally by titration (DIN EN ISO 15880, see also the examples) or calculated from the acid number of the unneutralized polymer and the amount of neutralizing agent applied for neutralization.

[0036] The above describes the general principles and conditions for neutralization and conversion of acid groups to the corresponding basic groups by way of example in the context of prepolymer (a). However, preferably, prepolymer (a) is not neutralized in the context of the present invention. Rather, in the context of the method of the present invention, it is essential that the neutralization step be carried out at a later stage of the method, i.e., during the dispersion process described below (i.e., the stage in which the prepolymer is dispersed in the aqueous phase, meaning that at this stage the prepolymer begins to convert and ultimately obtain a polyurethane-based dispersion). However, ultimately, each acid group of the prepolymer is also part of the polymer species contained in the polyurethane-based dispersion or the finally produced polyurethane-polyurea dispersion. Therefore, the principle of neutralization is quite obviously generally valid.

[0037] To introduce the acid groups, it is possible to use starting compounds in the preparation of the prepolymer (a) that contain the above groups, such as carboxylic acid groups, as well as reactive groups, preferably hydroxyl groups, for the preparation of urethane bonds, so that the groups are introduced into the prepolymer.

[0038] The corresponding compounds intended for introducing preferred carboxylic acid groups are polyether polyols and / or polyester polyols, and may contain carboxyl groups. However, preferentially used compounds are low-molecular-weight compounds having at least one carboxylic acid group and at least one functional group reactive with isocyanate groups, preferably a hydroxyl group. In the context of the present invention, the expression "low-molecular-weight compound" should be understood to mean a compound that can be assigned an individual molecular weight, preferably as a monomeric compound, as opposed to a high-molecular-weight compound, especially a polymer. Therefore, low-molecular-weight compounds are not particularly polymeric, since polymers are always mixtures of molecules and must be described using an average molecular weight. Preferably, the term "low-molecular-weight compound" is understood to mean that the corresponding compound has a molecular weight of less than 300 g / mol, preferably in the range of 100 to 200 g / mol.

[0039] Preferred compounds in this context are, for example, monocarboxylic acids containing two hydroxyl groups, such as dihydroxypropionic acid, dihydroxysuccinic acid, and dihydroxybenzoic acid. Very particular compounds are α,α-dimethylolalkanoic acids, such as 2,2-dimethylolacetic acid, 2,2-dimethylolpropionic acid, 2,2-dimethylolbutyric acid, and 2,2-dimethylolpentanoic acid, especially 2,2-dimethylolpropionic acid.

[0040] Preferably, the prepolymers (a) applied in this process are therefore carboxy-functional. They preferably have an acid number of 10 to 35 mg KOH / g, more particularly 15 to 23 mg KOH / g (based on solids). As already mentioned above, the prepolymers (a) applied in this process are preferably not neutralized, i.e., the MEQ base of the prepolymers (a) is 0 mmol / g or at least substantially 0 mmol / g.

[0041] As mentioned above, the prepolymer (a) is preferably constructed from difunctional compounds, in particular diisocyanates and diols, and therefore the prepolymer is preferably linear.

[0042] As outlined above, the prepolymer (a) contains isocyanate groups. The polyurethane prepolymer preferably has an isocyanate equivalent weight of less than 3000 g / mol. More preferably, the isocyanate equivalent weight is less than 2500 g / mol. A preferred range is 500 to 3000 g / mol, and even more preferably 1000 to 2500 g / mol (as determined via the NCO content (solids) of the prepolymer).

[0043] Prepolymer (a) preferably has a number average molecular weight of up to 6000 g / mol, for example in the range of 1000 to 6000 g / mol, more preferably 2000 to 5000 g / mol. A relatively low molecular weight contributes to a correspondingly low viscosity of the prepolymer, which means that a viscosity more closely matched to the aqueous phase (II) described below and therefore enhanced dispersibility is achieved.

[0044] Prepolymer (a) can be prepared by known and established methods, particularly by reacting the starting compounds in bulk or solution in an organic solvent, such as methyl ethyl ketone, at temperatures ranging from 60 to 120 °C, optionally using a catalyst typical for polyurethane preparation. Such catalysts are known to those skilled in the art, one example being dibutyltin laurate. The key here, of course, is to select the proportions of the starting components so that the product, i.e., prepolymer (a), contains isocyanate groups. Similarly, it is immediately clear that the solvent should be selected so as not to undergo unwanted reactions with the functional groups of the starting compounds, i.e., so as to be inert to these groups and not to interfere with their reaction. The preparation is preferably carried out in organic solvent (b), as described below. Furthermore, the proportion of organic solvent for preparing prepolymer (a), based on the synthesis mixture (i.e., the mixture containing the starting compounds and the organic solvent), preferably does not exceed the proportion of organic solvent (b) in the organic base phase, as defined below.

[0045] The organic-based phase (I) may also comprise at least one organic solvent (b). Obviously, this organic solvent may be one of those applied within the manufacturing process of the prepolymer (a), or they may be.

[0046] The organic solvent (b) is not particularly limited and may be any solvent known to those skilled in the art, such as ketones, ethers, esters, pyrrolidones, amides, morpholines, lactones, acetates, or sulfoxides. Specific examples of the solvent (b) include methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, diethyl ether, dibutyl ether, dipropylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dibutyl ether, diglycol acetate, toluene, methyl acetate, ethyl acetate, butyl acetate, propylene carbonate, cyclohexanone, acetone, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, tetrahydrofuran, dioxane, N-formylmorpholine, dimethylformamide, or dimethyl sulfoxide, 3-methoxy-N,N-dimethylpropionamide, 3-butoxy-N,N-dimethylpropionamide, N-formylmorpholine, γ-butyrolactone, and bis(2-(2-butoxyethoxy)ethoxy)methane.

[0047] The proportion of the at least one organic solvent (b) is 20% by weight or less (20 wt.-%), based on the total weight of the organic-based phase (I). Therefore, the organic-based phase (I) may even be completely free of such organic solvents (meaning that in such cases the organic-based phase may consist of the prepolymer (a)). However, for reasons of an adequately low viscosity, the proportion of the at least one organic solvent (b) is preferably 5% by weight or more. Preferably, the proportion is 5 to 20% by weight, more preferably 10 to 15% by weight, in each case based on the total weight of the organic-based phase. The relatively low proportion of organic solvent, together with the further characteristics and technical features of the inventive method described below, ensures that the final aqueous polyurethane-polyurea dispersion can be prepared with a very low content of organic solvents, without the need for a separate distillation step of such solvents.

[0048] The solids content of the organic-based phase (I) is preferably at least 80% by weight, more preferably at least 85% by weight, but preferably less than 90% by weight. A preferred range is 80 to 95% by weight, for example 85 to 90% by weight.

[0049] In the second step (2) of the process of the present invention, an aqueous phase (II) is provided. It will be appreciated that the second step can be carried out before, after or in parallel with the first step (1).

[0050] The aqueous phase (II) obviously comprises water. Of course, in addition to water, the aqueous phase may also contain, in proportion, typical adjuvants such as typical emulsifiers and protective colloids. A compilation of suitable emulsifiers and protective colloids is described, for example, in Houben Weyl, Methoden der organischen Chemie [Methods of Organic Chemistry], volume XIV / 1 Makromolekulare Stoffe [Macromolecular compounds], Georg Thieme Verlag, Stuttgart 1961, p. 411ff. The aqueous phase may also contain alkali metal hydroxides as neutralizing agents, which contribute to or completely cover the essential step of neutralization during the dispersion procedure. However, water, of course, constitutes the majority of the aqueous phase (II), for example, at least 90% by weight, or at least 95% by weight.

[0051] In step (3) of the method of the present invention, the organic-based phase (I) and the aqueous-based phase (II) are continuously fed into a high-shear dispersing device comprising a rotor / stator unit. It is essential that the two phases come into contact within the rotor / stator unit, and therefore do not come into contact before reaching this rotor / stator unit. Typically, the high-shear dispersing device comprises one rotor / stator unit. In the unlikely event that more than one such unit is present within the device, the rotor / stator unit is of course the first unit to which both the organic-based phase (I) and the aqueous-based phase (II) are fed.

[0052] High shear dispersing equipment with rotor / stator units and its application to continuous dispersion processes are well known in the art.For example, EP 1 489 130 B1 or US 8,669,401 B2 describe details of such equipment for the continuous production of polyurethane emulsions or wax dispersions.

[0053] Thus, such a rotor / stator unit comprises a rotor subunit and a stator subunit. Both the rotor subunit and the stator subunit include at least one set of teeth, whereby the teeth of each set are assembled circumferentially on a circle having a constant circumference and diameter. At least one set of rotors and at least one set of stators are aligned with each other so that the teeth of the rotors and stators (each forming a circle) are concentric with each other. When the rotor and / or stator have two or more tooth rows (which is preferred in the context of the present invention), the tooth rows of the rotors and stators are arranged alternately. In known rotor / stator units, the liquid components to be dispersed are introduced centrally into the device, and each rotation of the rotors subjects the liquid to centrifugal force, ultimately forcing the medium outward. The movement of the rotors also results in rotation of the rotor teeth relative to the fixed teeth of the stator, thereby imparting shear to the liquid as it flows outward through the device's dynamically changing cavities / cavity sizes. More specifically, the dynamic change in cavity / cavity size is based on the rotation of the rotor teeth relative to the fixed stator teeth. Obviously, various parameters can be adjusted, such as the number and size of the teeth, the diameter of the tooth row (the circle on which the teeth are arranged), the gap width / distance between a set of teeth, and / or the distance between the rotor and stator teeth (the concentric distance between a tooth in the rotor tooth row and a tooth in the adjacent stator tooth row), or the number of rotor and stator teeth. These parameters can generally be adjusted based on individual needs and the general knowledge of those skilled in the art. As a general rule, as the tooth diameter increases, the number of teeth often increases, while the tooth size and gap number decrease (i.e., the number of fracture walls increases, resulting in shear stresses (at a given rotor speed)).

[0054] Preferably, the rotor / stator unit includes at least two sets of teeth on the rotor (21) and at least two sets of teeth on the stator (11). More preferably, it includes at least three sets of teeth on the rotor (21) and at least three sets of teeth on the stator (11). Even more preferably, it includes four sets of teeth on the rotor (21) and three sets of teeth on the stator (11). As mentioned above, the set of teeth on the rotor (21) and the set of teeth on the stator (11) are, of course, alternately arranged. Thus, in the above scenario of four sets of teeth on the rotor (21) and three sets of teeth on the stator (11), the first set of teeth on the rotor (21) has the smallest overall diameter (and therefore is most centrally located), and the fourth set of teeth (21) has the largest overall diameter (and therefore is most outermost).

[0055] (3.1) As mentioned above, the two phases, i.e., the organic-based phase (I) and the aqueous phase (II), are brought into contact within the rotor / stator unit and therefore not before reaching this rotor / stator unit. Clearly, therefore, the first requirement is that the two phases are fed separately as two separate feed streams from two separate inlets into the high shear disperser and thus into the rotor / stator unit.

[0056] (3.2) It is also crucial that the organic phase (I) is fed to the rotor / stator unit in the form of multiple sub-feed streams via multiple inlets. Thus, for example, the organic phase (I) may initially be fed as one (main) feed stream, but may be split into multiple sub-feed streams before reaching the rotor / stator unit, and subsequently fed into the unit as such multiple sub-feed streams.

[0057] The above features (3.1) and (3.2) have been found to be crucial for achieving the objectives of the present application, i.e., for providing aqueous polyurethane-polyurea dispersions that allow the production of dispersions with a very low content of organic solvent, while at the same time providing the dispersion with optimal and stable dispersion properties. More particularly, the two separate feed streams (3.1) ensure a continuous, constant and controllable supply of both phases to the unit (as opposed to a single feed stream containing both phases, since in this scenario the viscosity difference between the two phases would prevent such a continuous, constant and controllable supply), while the supply of the organic phase in the form of several sub-feed streams (3.2) serves to enhance the dispersion effect.

[0058] Preferably, in the first embodiment, the above principle involves one first inlet to the rotor / stator unit being located centrally within the unit, i.e., inside the circle described by the smallest, and therefore innermost, tooth row (which is either the rotor or stator tooth row). Of course, the inlet is part of the stator. Thus, this first embodiment is identical to the inlet of a standard rotor / stator unit. This first inlet is provided for the feed streams of aqueous phase (II) and aqueous phase (II), respectively.

[0059] As described above, in the novel method, the organic phase (I) is supplied through multiple inlets. These inlets may also be called "second inlets" to distinguish them from the first inlet for the organic phase (I). These multiple inlets (i.e., multiple second inlets or a set of second inlets) are provided for the organic phase (I) and multiple sub-feed streams of the organic phase (I), respectively. Of course, the inlets are part of the stator. The set of second inlets is a partition of a single main inlet pipe in the rotor / stator unit. In other words, the single main feed pipe is divided into the respective number of feed inlets.

[0060] The number of second inlets constituting the set of second inlets is preferably at least 5, more preferably at least 10, or even at least 20. Of course, the exact number of second inlets depends on additional factors, such as the overall size of each rotor / stator unit and the size (i.e., inner diameter) of the inlets. The inner diameter of the second inlets also varies and is selected according to individual needs. For example, the appropriate size of the second inlets is influenced by the viscosity of the organic phase (I) or its mass flow rate. Exemplary size ranges (not meant to be limiting, only preferences) can be 1.5-10 mm, such as 1.8-7.5 mm or 1.8-5 mm (inner diameter).

[0061] One crucial advantage of this setup is that the organic phase (I) is already subjected to a certain level of shear before reaching the rotor / stator unit (due to the multiple inlet geometry, i.e., the relatively high number of walls and therefore significant turbulence). Also, since the organic phase (I) is fed into multiple sub-feeds rather than a single main feed stream, it initially arrives at the rotor / stator unit in a well-dispersed state.

[0062] The set of second inlets can be arranged in different ways. For example, a second inlet as part of the stator can be arranged between the central first inlet and the first set of stator teeth (i.e., the stator teeth with the smallest diameter). Alternatively, the second inlets can be arranged between the second set of stator teeth. Obviously, the first part of the second inlets can also be located between the central first inlet and the first set of stator teeth, and the second part can be located between the second set of stator teeth (or the second part can be divided into groups of inlets located between different sets of stator teeth). It is preferred that at least some of the second inlets, and more preferably all of the second inlets, are located between the two sets of stator teeth.

[0063] The second inlets as part of the stator are preferably arranged circumferentially on a circle having a constant circumference and diameter. The second inlets are preferably uniformly distributed on said circle, i.e., arranged at a uniform distance from one another on such a circle. Therefore, this circle preferably has a circumference and diameter that is between the circumference and diameter of the first set of stator teeth and the circumference and diameter of the second set of stator teeth, which means that the second inlets are located between two sets of stator teeth.

[0064] Preferably, the second set of inlets is a circumferential set of inlets (i.e., holes) having a circumference and diameter greater than the circumference and diameter of at least one set of stator teeth and at least one set of rotor teeth.

[0065] Preferably, some of the second inlets (preferably all of the second inlets) are arranged radially outward of at least one set of rotor teeth and at least one set of stator teeth, for example radially outward of two sets of rotor teeth and one set of stator teeth (lying between two sets of rotor teeth). For greater clarity, the rotor tooth row from which the second inlets are arranged radially outward may be named rotor tooth row (21 a), and the respective stator set of teeth may be named stator tooth row (11 a).

[0066] Thus, in a preferred embodiment, the second inlet is positioned at a position where the fluid entering the unit via the first inlet (i.e., aqueous phase (II)) passes through the unit in a form already subjected to shear.

[0067] The rotor and stator teeth of the rotor / stator device are arranged concentrically with each other, and if there are two or more rotor and stator tooth rows, the rotor and stator tooth rows are arranged alternately, so that the second set of inlets as part of the stator is preferably arranged at least substantially on a circle that circles the rotor tooth rows (see Figure 3). Thus, the second set of inlets (which are stator holes) is arranged directly or approximately (i.e., slightly offset) below each rotor tooth row. Each space defined by these conditions is the area where a first fluid entering the unit through a first inlet comes into contact with a second fluid entering the unit through a second set of inlets.

[0068] Obviously, the organic phase (I) entering the unit through the second set of inlets must be effectively dispersed with the aqueous phase (II) and therefore must be effectively exposed to shear in order to effectively develop adequate dispersion properties. Therefore, preferably, the rotor / stator unit includes at least one combination of a set of rotor teeth and a set of stator teeth radially outward from the location of the second inlets. Therefore, if the second set of inlets is arranged as a circle, the circumference and diameter of this circle are smaller than the circumference and diameter of the at least one set of stator teeth and at least one set of rotor teeth.

[0069] Thus, preferably, some of the second inlets (preferably all 22 inlets) are arranged radially inward of at least one set of rotor teeth and at least one set of stator teeth, for example radially inward of two sets of rotor teeth and two sets of stator teeth (arranged alternately). For clarity, the set of rotor teeth to which the second inlets are arranged radially inward may be named rotor tooth row (21b), and the respective stator set of teeth may be named stator tooth row (11b).

[0070] As those skilled in the art know, the viscosity of the organic phase containing polyurethane prepolymer and a relatively low solvent content will be significantly higher than the viscosity of the aqueous phase. Surprisingly, the above setup addresses these hurdles, i.e., ensures an effective dispersion process despite the respective deviations in the viscosities of the mixed phases.

[0071] As mentioned above, the organic phase may be heated before being introduced into the high-shear dispersing device, i.e., the rotor / stator unit. This obviously reduces the viscosity. Preferably, the temperature of the organic phase (I) is at least 50°C, more preferably at least 65°C, or even at least 75°C when it is introduced into the rotor / stator unit and when it is contacted with the aqueous phase (II). The preferred range is 50 to 160°C, more preferably 65 to 140°C, or even 75 to 120°C.

[0072] The organic phase preferably has a viscosity of less than 35 Pas, preferably 15 to 30 Pas (measured in a rotational viscometer at a shear rate of 10 / s), when introduced into the rotor / stator unit, which viscosity can be reached when the organic phase is heated to the temperatures mentioned above.

[0073] Preferably, the temperature of the aqueous phase (II) when introduced into the rotor / stator unit and when contacted with the organic phase (I) is below 25° C., more preferably below 15° C., or even below 10° C. A preferred range is 1 to 15° C., more preferably 2 to 10° C. As is generally known, at such temperatures the viscosity of water, and therefore of the aqueous phase (II), is significantly lower than that of the organic phase (I) described above (for example, below 10 mPas at a shear rate of 1000 / s).

[0074] The preferably low temperature of the aqueous phase quite obviously serves as a compensation for the preferably high temperature of the organic phase, meaning that the emerging aqueous polyurethane-based dispersion can have a moderate temperature after the phases are brought into contact and, as a result, the continuous dispersion step (4) of the present method is initiated. To enhance this cooling effect, the rotor / stator unit or a portion thereof can be cooled by external means. In principle, the same can be done for the fluid piping system connecting to the outlet of the rotor / stator unit. The temperature, of course, also depends on the mass ratio of the two different phases during the production of the aqueous polyurethane-based dispersion and, therefore, the mass flow rate, but is preferably between 30 and 80°C, or even 40 and 70°C, upon exiting the rotor / stator unit. One reason for this is that, unlike the prepolymer and organic-based phase (I), the emerging aqueous dispersion often has a higher viscosity at high temperatures, which can lead to improper flow at too high a temperature.

[0075] The ratio of the mass flow rates of the organic phase (I) and the aqueous phase (II) entering the rotor / stator unit can be selected according to individual needs, such as the desired solids content of the resulting dispersion. The ratio (I):(II) can be, for example, 1:4 to 1.5:1.

[0076] As already mentioned above, the preparation of aqueous polyurethane-polyurea dispersions must include a neutralization step using at least one alkali metal hydroxide as a neutralizing agent during the dispersion process according to steps (3) and (4) above. By "dispersion process" is meant the actual dispersion process according to steps (3) and (4) of the process of the present invention, i.e., the contacting of the two phases and subsequent dispersion in the rotor / stator unit. During this process, the acid groups initially present in the prepolymer are at least partially neutralized, i.e., converted to the corresponding bases. In principle, neutralization can be carried out not only during the dispersion process but also before or after the dispersion process. However, it is preferable not to carry out such neutralization before the dispersion process, e.g., directly during or after the formation of the prepolymer. A significant advantage of this is that potential side reactions between the isocyanate groups and the neutralizing agent are avoided or at least reduced. The latter is particularly important when the organic-based phase is heated before the dispersion process to reduce its viscosity. This will be discussed in more detail below.

[0077] As already mentioned above, neutralization during the dispersion process is preferably achieved by including an alkali metal hydroxide as a neutralizing agent in the aqueous phase (II).

[0078] If a further neutralization step is carried out after the dispersion process, this can be carried out, for example, by simply adding the neutralizing agent (e.g., in the form of an aqueous solution) to the final holding vessel for the aqueous polyurethane-polyurea dispersion being produced, or in the form of a continuous feed, for example, via a T-joint in the piping system.

[0079] Preferably, within the process of the present invention, nitrogen-containing organic bases, such as amines, for example ammonia, trimethylamine, triethylamine, tributylamine, dimethylaniline, triphenylamine, dimethylethanolamine, methyldiethanolamine or triethanolamine, as well as mixtures thereof, are not applied as neutralizing agents.More preferably, within the process of the present invention, only alkali metal hydroxides are applied as neutralizing agents.

[0080] The final aqueous polyurea-polyurethane dispersion is characterized by an MEQ base of 0.125 to 0.625 mmol / g (based on solids). Therefore, if the acid value of the applied prepolymer (a) is relatively high, and thus the acid value of the final aqueous polyurea-polyurethane dispersion is relatively high, a high degree of neutralization will result in a relatively high MEQ base. If the acid value of the applied prepolymer (a) is relatively low, and thus the acid value of the final aqueous polyurea-polyurethane dispersion is relatively low, a lower degree of neutralization will result in a relatively low MEQ base. A preferred range for the MEQ base is 0.15 to 0.5 mmol / g, or even 0.20 to 0.40 mmol / g.

[0081] In a preferred embodiment, the degree of neutralization of the final aqueous polyurethane-polyurea dispersion is greater than 65%, such as greater than 66%, or even greater than 70%. Overall, the degree of neutralization of the final aqueous polyurethane-polyurea dispersion is preferably greater than 70% to 95%.

[0082] A two-stage neutralization process, i.e., a first neutralization step during the dispersion step defined above and a second neutralization step after the dispersion step, is preferably carried out by adding an alkali metal hydroxide as a neutralizing agent to a final collection vessel. From the above, the first neutralization step is preferably carried out at a temperature of the mixture to be neutralized of 30 to 80°C or 40 to 70°C. The second neutralization step is preferably carried out at a temperature of the mixture to be neutralized of less than 35°C, such as 10 to 30°C (i.e., room temperature). Thus, the degree of neutralization achieved in the first step is preferably 50 to 70%, and the degree of neutralization achieved in the second step is preferably 70 to 95% (the sum of the first and second steps). (The degree of neutralization in each case is calculated as the molar ratio of potentially present anionic groups in the prepolymer to the amount of neutralizing groups in the applied neutralizing agent (see the Examples section for further details), always taking into account the respective mass flow rates of the respective phases in a continuous process.)

[0083] While neutralization may contribute to the stabilization of the aqueous polyurethane-polyurea dispersion, the addition of neutralizing agents at different temperatures and / or conditions / reaction progressions during the process of the present invention may affect the viscosity and particle size of the final aqueous polyurethane-polyurea dispersion. In the preferred embodiments described above, these effects are taken into consideration to optimize the resulting aqueous polyurethane-polyurea dispersion.

[0084] During the continuous dispersion step (4), an aqueous dispersion containing polyurethane-based species is formed. Apparently, during and after this process, a proportion of the isocyanate groups of the prepolymer react with water to form primary amino groups. These emerging amino groups then react with the remaining isocyanate groups of the prepolymer. These reactions inevitably occur at the moment the two phases (I) and (II) are brought into contact with each other, i.e., in the rotor / stator unit, and also during and after the continuous discharge of the aqueous polyurethane-based dispersion from the high-shear disperser in step (5) of the process of the present invention.

[0085] Furthermore, in step (6) of the method of the present invention, at least one chain extender is continuously added to the aqueous polyurethane-based dispersion discharged from the rotor / stator unit, thereby producing an aqueous polyurethane-polyurea dispersion. The chain extender thus reacts with the polyurethane-based species in the polyurethane-based dispersion, more particularly with the isocyanate groups of these polyurethane-based species. Therefore, care must be taken to ensure that a sufficient amount of isocyanate groups remains for reaction with the chain extender. As those skilled in the art know, the reaction of isocyanate with water (which produces amino groups, which further consume isocyanate) does not occur on an extremely fast reaction scale. In other words, the reactions and transformations mentioned above proceed in parallel with each other. Ultimately, as a result of this inter- and intramolecular reaction or crosslinking, a dispersion containing polyurethane-polyurea particles is formed.

[0086] As mentioned above, in step (6), at least one chain extender is fed to the aqueous polyurethane-based dispersion discharged from the rotor / stator unit, which means that a chain extension reaction with the isocyanate takes place.

[0087] The chain extenders that can be used are those established and known to those skilled in the art, and thus have an NH functionality, for example in the form of a primary or secondary amino group or a hydrazine moiety.

[0088] Thus, exemplary chain extenders are aliphatic, aromatic, or araliphatic (mixed aliphatic-aromatic) polyamines, such as diamines or triamines, and also hydrazines or hydrazides.

[0089] Specific examples include ethylenediamine (EDA), diethylenetriamine (DETA), 3-(2-aminoethylamino)propylamine (N3-amine), dipropylenetriamine (DPTA), triethylenetetramine (TETA), N,N'-bis-(3-aminopropyl)ethylenediamine (N4-amine), meta-xylylenediamine (MXDA), N-(2-aminoethyl)ethanolamine (AEEA), N-(2-aminoethyl)propanolamine (AEPA), 2-methylpentanediamine, and the like, and mixtures thereof.Also suitable for implementing the present invention are 1,2-propanediamine, 1,3-propanediamine, 1,3-butanediamine, 1,4-butanediamine, 2,2-dimethylpropane-1,3-diamine, 1,6-hexamethylenediamine, octamethylenediamine, dimer fatty acid (C36) diamine, 1,2-cyclohexanediamine, 1,4-cyclohexanediamine, 2-methylcyclohexane-1,3-diamine, 4-methylcyclohexane-1,3-diamine, 3-(cyclohexylamino)propane ... Pyramine, 4,4'-dicyclohexylmethanediamine, 2,4'-dicyclohexylmethanediamine, 3,3'-dimethyl-4,4'-dicyclohexylmethanediamine, 3,3'-dimethyl-2,4'-dicyclohexylmethanediamine, isophoronediamine, piperazine, 2-methylpiperazine, 2,5-dimethylpiperazine, 2-imidazolidinonediamine, 1,2-phenylenediamine, 1,4-phenylenediamine, 4,4'-diaminodiphenylmethane, 2,4'-diaminodiphenylmethane , 2,6-diamino-4-phenyltriazine, 2,4-diamino-6-phenyl-1,3,5-triazine, 3,3-dichlorobenzidene, 4,4'-methylene-bis-(2-chloroaniline), 3,3-dichloro-4,4-diaminodiphenylmethane, 4,7,10-trioxatridecane-1,13-diamine, 4,9-dioxadodecane-1,12-diamine, N-[3-(isodecyloxy)propyl]propane-1,3-diamine, sulfonated primary and / or secondary amines, such as N-(2-aza-2-methyl-2-phenyl)-2-propanediamine, and mixtures thereof.

[0090] Preferred chain extenders are polyamines having at least three amino groups, such as at least two primary amino groups and at least one secondary amino group. More preferably, there are exactly three amino groups, more particularly two primary amino groups and one secondary amino group. One preferred polyamine is diethylenetriamine.

[0091] The chain extender is preferably supplied in the form of an aqueous composition to the aqueous polyurethane-based dispersion discharged from the high-shear disperser and the rotor / stator unit, respectively. For example, the aqueous composition can be a solution or dispersion of the chain extender in water, with a chain extender concentration of 5 to 20% by weight based on the composition. Preferably, the aqueous composition is supplied continuously. The actual desired concentration of chain extender will obviously depend on various factors, such as the mass flow rate of the aqueous polyurethane-based dispersion discharged from the high-shear disperser, the concentration of polyurethane-based species in the dispersion, the isocyanate content of the polyurethane-based species, or the mass flow rate of the composition containing the chain extender. Taken together, these parameters can be adjusted according to individual needs. Continuous supply of the chain extender can be accomplished via a T-joint in the piping system. To ensure proper mixing, a mixing device, such as a static mixer, can be placed in the system after the point where the chain extender is supplied.

[0092] Preferably, the molar ratio of the isocyanate groups of the polyurethane-based dispersion (calculated as the isocyanate groups contained in the prepolymer of the organic phase (I)) to the sum of the primary and secondary amino groups of the chain extender (calculated from the concentration of each agent in the aqueous composition) is greater than 0.8:1, for example, 0.8:1 to 3:1 or 0.9:1 to 2:1.

[0093] Therefore, in a preferred embodiment, the continuous mass flow of the polyurethane-based dispersion discharged from the high-shear dispersing device and the continuous mass flow of the composition containing the chain extender are adjusted so that the molar ratio of the isocyanate groups of the polyurethane-based dispersion (calculated as the isocyanate groups contained in the prepolymer of the organic phase (I)) to the sum of the primary amino groups and secondary amino groups of the chain extender (calculated from the concentrations of each agent in the aqueous composition) is greater than 0.8:1, for example, 0.8:1 to 3:1 or 0.9:1 to 2:1.

[0094] The fact that the chain extender is added only after the dispersion has left the high shear disperser has the advantage that no effective cross-linking caused by the chain extender takes place within the equipment, thus avoiding potential clogging and blocking processes in the complex cavity system of the equipment.

[0095] On the other hand, as mentioned above, it is necessary to take into consideration that the reaction of isocyanate with water produces amino groups, which then consumes more isocyanate. Those skilled in the art can select and adapt appropriate conditions so that the addition of the chain extender is carried out at a time when an effective reaction between the isocyanate and the chain extender is still ensured.

[0096] In a preferred embodiment, the time between the time the dispersion exits the high shear disperser and the time the chain extender is added (hereinafter referred to as "residence time") is 30 seconds or less. Preferably, the residence time is 20 seconds or less, or even 10 seconds or less, or 5 seconds or less. The residence time (which is an average statistical number) can be calculated by taking into account the mass flow rate of the aqueous polyurethane-based dispersion continuously discharged from the rotor / stator unit (and thus the high shear disperser) and the volume that the polyurethane-based dispersion must pass through each piping system before the chain extender is added (e.g., the volume calculated based on the inner diameter of the piping system and the distance between the point where the aqueous polyurethane-based dispersion exits the high shear disperser and the point where the chain extender is added). More specifically, the calculation is performed based on the parameters of the mass flow rate, the inner diameter of the piping system, the length of the associated piping system (the point where the high shear disperser exits and the point where the chain extender is added), and the density of the aqueous dispersion exiting the high shear disperser (for the calculation, the density at a temperature of 60°C was taken).

[0097] From the above, therefore, residence time is the average time that a portion of the aqueous dispersion, ie, the polyurethane species, is in contact with water, but does not include the chain extender.

[0098] Step (6) of the method of the present invention, i.e., adding a chain extender and thereby initiating the reaction of the chain extender, particularly the amino groups, with the isocyanate, ultimately leads to the production of an aqueous polyurethane-polyurea dispersion. This dispersion can be collected, for example, in a holding vessel. Of course, it is also possible to transport the dispersion directly via a pipe system to further processes and respective plant setups, such as processes and setups for producing coating materials.

[0099] The final aqueous polyurethane-polyurea dispersion is characterized in that the polyurethane-polyurea particles present in the dispersion have an average particle size (volume-based mean diameter) of 50 nm to 500 nm, more preferably 50 to 300 nm, and most preferably 50 to 250 nm (measured via photon correlation spectroscopy as described in the Examples section).

[0100] A further aspect of the present invention is an aqueous polyurethane-polyurea dispersion comprising polyurethane-polyurea particles having a volume-based average diameter of 50 to 500 nm. The dispersion is further characterized by 0.125 to 0.625 mmol / g (based on solids) of MEQ base. Preparation of the dispersion also requires a neutralization step using at least one alkali metal hydroxide as a neutralizing agent.

[0101] The aqueous polyurethane-polyurea dispersion preferably has a gel fraction of at least 60%, more preferably at least 70%, and particularly preferably at least 80%. The gel fraction can therefore reach up to or nearly 100%, such as 99% or 98%, for example. In such cases, the polyurethane-polyurea polymer is entirely or almost entirely present in the form of crosslinked particles.

[0102] Therefore, the dispersion is preferably a microgel dispersion, i.e., a polymer dispersion in which, on the one hand, the polymer is present in the form of relatively small particles, i.e., microparticles, and, on the other hand, the polymer particles are at least partially intramolecularly crosslinked. As is known, such microgel dispersions offer significant advantages in the versatility of coating materials, such as, for example, pigmented automotive coating compositions. Such properties include, for example, on the one hand, the excellent optical and mechanical properties of the cured coatings prepared with such coating materials, and on the other hand, the high solids content and good storage stability of aqueous coating materials, especially pigmented coating materials such as basecoat materials.

[0103] The proportion of polyurethane-polyurea polymer in the aqueous dispersion is preferably 25 to 55% by weight, preferably 30 to 50% by weight, more preferably 35 to 45% by weight, in each case based on the total amount of the aqueous dispersion. The solids content of the aqueous dispersion is therefore quite obviously preferably 25 to 55%, preferably 30 to 50%, more preferably 35 to 45%. The proportion of water in the dispersion is preferably 40 to 70% by weight, more preferably 45 to 65% by weight, even more preferably 50 to 60% by weight, in each case based on the total amount of the dispersion.

[0104] The aqueous dispersion preferably consists of at least 90% by weight of polyurethane-polyurea polymer and water (calculated as the sum of the proportion of water and the solids content (wt.-%) of the dispersion).

[0105] Therefore, the content of organic solvent in the aqueous dispersion is very low, preferably not more than 10% by weight based on the total weight of the dispersion. Specifically, as pointed out above, this very low content of organic solvent is achieved without the need for a final distillation step to remove such organic solvent. Therefore, the method of the present invention preferably does not include such a distillation step (although it does not, of course, exclude it). Furthermore, if such a distillation step is carried out, this step usually requires only a very small amount of organic solvent to be removed. Therefore, if a distillation step is carried out, this step is relatively low in energy and / or time consumption compared to those known from the prior art.

[0106] In a preferred embodiment, the process of the present invention therefore does not comprise a distillation step or comprises a distillation step in which an organic solvent representing not more than 5% by weight of the aqueous dispersion before distillation is distilled off, but which nevertheless results in an aqueous polyurethane-polyurea dispersion having an organic solvent content of less than 10% by weight.

[0107] The present invention will be described below with reference to examples. [Example]

[0108] 1. Solids Unless otherwise stated, the solids content (hereinafter also referred to as percent solids) was determined at 130°C; 60 min, with an initial mass of 1.0 g according to DIN EN ISO 3251. When referring to an official standard in the context of the present invention, this of course means the version of the standard that was current on the filing date, or, if no new version existed on that date, the most recent new version.

[0109] 2. Isocyanate content The isocyanate content (hereinafter also referred to as NCO content) was determined by potentiometric back titration of the amine excess with 0.1 N hydrochloric acid after adding an excess of a 2% strength N,N-dibutylamine solution in xylene to a homogeneous solution of the sample in acetone / N-ethylpyrrolidone (1:1, vol.%), according to DIN EN ISO 3251, DIN EN ISO 11909, and DIN EN ISO 14896. The NCO content of the polymer can be back-calculated via the proportion of polymer (solids) in the solution, based on the solids content.

[0110] 3. Hydroxyl value The hydroxyl number was determined by complete hydrolysis of the excess acetic anhydride remaining after acetylation with acetic anhydride in tetrahydrofuran (THF) / dimethylformamide (DMF) solution at room temperature in the presence of 4-dimethylaminopyridine as catalyst, followed by potentiometric back titration of acetic acid with alcoholic potassium hydroxide solution, according to R.-P. Krueger, R. Gnauck, and R. Algeier, Plaste und Kautschuk, 20, 274 (1982). Acetylation times of 60 min were sufficient in all cases to ensure complete conversion.

[0111] 4. Acid value The acid number was determined by adding ethanolic potassium hydroxide solution to a homogeneous solution of tetrahydrofuran (THF) / water (9 parts by volume of THF and 1 part by volume of distilled water) according to DIN EN ISO 2114. Based on the determined acid number, the MEQ acid (meq / g solids) can be calculated as "MEQ acid = acid number / 56.105".

[0112] 5. MEQ base According to DIN EN ISO 15880, the MEQ base (meq / g solids) was determined in a homogeneous solution of tetrahydrofuran (THF) / water (9 parts by volume THF and 1 part by volume distilled water) by neutralization with hydrochloric acid.

[0113] 6. Degree of neutralization The degree of neutralization of a component was calculated from the amount of carboxylic acid groups present in the component (determined by the acid number) and the amount of neutralizing groups (i.e., bases) in the neutralizing agent used. The degree of neutralization can also be calculated as follows: "Degree of neutralization = (MEQ base / MEQ acid) x 100%".

[0114] 7.Solvent content The amount of organic solvent in a mixture, if not / could not be determined by mass measurement during the preparation of such a mixture, was determined by gas chromatography (Agilent 7890A, 50 m silica capillary column with polyethylene glycol phase or 50 m silica capillary column with polydimethylsiloxane phase, helium carrier gas, 250 °C split injector, 40–220 °C oven temperature, flame ionization detector, 275 °C detector temperature, n-propylene glycol as internal standard).

[0115] 8.Number average molecular weight The number-average molar masses (Mn) were determined, unless otherwise stated, using a vapor pressure osmometer (VPO) 10.00 (Knauer) in a concentration series in toluene at 50°C using benzophenone as the calibrant to determine the experimental calibration constant of the instrument used, according to the method of E. Schroeder, G. Mueller, KF Arndt, "Leitfaden der Polymercharakterisierung" [Principles of polymer characterization], Akademie-Verlag, Berlin, pp. 47-54, 1982.

[0116] 9.Particle size Depending on the (expected) size, the particle size was determined by laser diffraction or photon correlation spectroscopy (PCS). The defining parameter for describing particle size according to the present invention is the volume-based mean diameter (also called "D[4.3] / De Broucker mean" in the context of laser diffraction). For completeness, further parameters were also determined (see below).

[0117] Therefore, for all samples with a volume-based mean diameter of at least 600 nm measured by laser diffraction, this method was used to describe / define particle size. For all samples with a volume-based mean diameter measured by laser diffraction of less than 600 nm, an additional measurement of the volume-based mean diameter by PCS was performed, i.e., this method was used to describe / define particle size. The reason for this is that PCS is known to provide reliable results in the lower particle size range, while laser diffraction is considered optimal for the higher particle size range, respectively.

[0118] 9.1 Laser Diffraction Particle size values ​​were determined by laser diffraction in accordance with ISO 13220 using a Mastersizer 2000 particle size analyzer (Malvern Instruments). The instrument operates with a red light source (He-Ne, 633 nm, max. 4 mW) and a blue light source (LED, 470 nm, max. 0.3 mW). To determine the appropriate concentration range for the measurements, samples were diluted with particle-free deionized water (refractive index: 1.33) as the dispersing medium. The light blocking ratio was set to 3%–15% depending on the sample. Measurements were performed using a "Hydro 2000G" dispersion unit (Malvern Instruments). In each case, six measurements were performed at stirring speeds of 2000 1 / min and 3000 1 / min, and the measurements were repeated on a second, freshly prepared sample. The particle size analyzer was validated using particle size standards ranging from 0.2 to 190 μm. Calculations of the parameters describing particle size (see below) were performed using Malvern Instruments software (version 5.60) with the MIE approximation.

[0119] The following values ​​were determined: (D[2,3]) the arithmetic mean of the surface average (Sauter diameter) of the individual preparations; (D[4.3]) The arithmetic mean of the volume average values ​​(De Broucker mean, volume-based mean diameter) of the individual preparations, d(0.1) the value at which 10% of the total volume of particles have a particle size smaller than said value; d(0.5) the value at which 50% of the total volume of particles have a particle size smaller than the value; d(0.9) The value at which 90% of the total volume of particles have a particle size smaller than the value.

[0120] 9.2.PCS Measurements were performed using a Malvern Nano S90 (Malvern Instruments) at 25 ± 1 °C. The instrument was equipped with a 4 mW He-Ne laser at 633 nm. Samples (i.e., aqueous dispersions) were diluted with particle-free deionized water as the dispersing medium and then measured in 1 ml polystyrene cuvettes at appropriate scattering intensities. Evaluation was performed using a digital correlator and Zetasizer analysis software version 6.32 (Malvern Instruments). Measurements were performed five times and repeated on a second, fresh sample. The standard deviation of the five measurements was ≤4%. The maximum deviation of the volume-based mean diameter for five individual measurements was ±15%. The reported particle size was the arithmetic mean of the volume-based mean diameter measured for each preparation. Validation was performed using polystyrene standards with certified particle sizes ranging from 50 to 3000 nm.

[0121] 10. Gel Fractions The gel fraction of polyurethane-polyurea particles (microgel particles) present in aqueous dispersions was determined gravimetrically in the context of this invention. First, the polymer present was isolated from a sample of the aqueous dispersion (initial mass 1.0 g) by freeze-drying. After determining the solidification temperature (the temperature at which the electrical resistance of the sample showed no further change upon further reduction in temperature), the completely frozen sample was subsequently dried at a drying temperature 10°C below the solidification temperature, typically in the range of 5 mbar to 0.05 mbar. Rapid freeze-drying of the polymer was achieved by gradually increasing the temperature of the heated surface below the polymer to 25°C; after a drying time of typically 12 hours, the amount of isolated polymer (solids content determined by freeze-drying) remained constant and did not change with prolonged freeze-drying. Optimal drying of the polymer was then achieved by reducing the ambient pressure to its maximum (typically 0.05-0.03 mbar) and drying at a surface temperature below the polymer of 30°C.

[0122] The isolated polymer was then sintered in a forced air oven at 130°C for 1 min and then extracted in excess tetrahydrofuran at 25°C for 24 h (ratio of tetrahydrofuran to solid fraction = 300:1). The insoluble fraction (gel fraction) of the isolated polymer was then separated on a suitable frit and dried in a forced air oven at 50°C for 4 h, after which it was reweighed.

[0123] Furthermore, when the sintering time was varied between 1 and 20 minutes at a sintering temperature of 130 °C, the gel fraction of the microgel particles was confirmed to be independent of the sintering time. Therefore, a further increase in the gel fraction due to crosslinking reactions after isolation of the polymer solids can be excluded.

[0124] The gel fraction thus determined according to the invention is also called gel fraction (lyophilized).

[0125] In parallel, the gel fraction, also referred to below as gel fraction (130°C), was determined gravimetrically (solids content) by separating a polymer sample from the aqueous dispersion (initial mass 1.0 g) for 60 min at 130°C. After measuring the polymer mass, the polymer was extracted in excess tetrahydrofuran at 25°C for 24 h, similar to the procedure described above, after which the insoluble fraction (gel fraction) was separated, dried and reweighed.

[0126] Example P1 Preparation of polyurethane prepolymer (a) and organic phase (I) In a reaction vessel equipped with a stirrer, an internal thermometer, a reflux condenser, and electrical heating, 6110.6 parts by weight of a linear polyester polyol and 289.9 parts by weight of dimethylolpropionic acid (GEO Specialty Chemicals) were dissolved under nitrogen in 650.0 parts by weight of methyl isobutyl ketone (BASF SE) and 650.0 parts by weight of dipropylene glycol dimethyl ether (Proglyme®, BASF SE). The linear polyester diol was previously prepared from dimerized fatty acid (Radiacid® 0971, from Oleon), isophthalic acid (from BP Chemicals), and hexane-1,6-diol (from BASF SE) (mass ratio of starting materials: dimerized fatty acid to isophthalic acid to hexane-1,6-diol = 54.32:16.08:29.60), and had a hydroxyl number of 75 mg KOH / g on solids, a water content by Karl Fischer method of 0.02% by weight, a calculated number average molar mass of 1418 g / mol, and a number average molar mass determined by vapor pressure osmometry of 1390 g / mol. To the resulting solution at 30°C, 2269.9 parts by weight of dicyclohexylmethane 4,4'-diisocyanate (Desmodur® W, Bayer MaterialScience) having an isocyanate content of 32.0% by weight and 10.4 parts by weight of dibutyltin dilaurate (Merck) were added in sequence. The mixture was heated to 80°C with stirring. Stirring was continued at this temperature until the isocyanate content of the solution became constant at 2.00% by weight.

[0127] Once the isocyanate level was determined to be constant, the polyurethane prepolymer and each organic phase (I) were maintained at 82°C under nitrogen and processed for an additional 12 hours, during which time the isocyanate level and viscosity remained constant.

[0128] The properties of the prepolymer / organic phase (I) were as follows: Solid content (130℃, 60 minutes, 1g): 87.1% by mass NCO content (reactor): 2.00% by mass Dipropylene glycol dimethyl ether content (GC): 6.5% by mass Methyl isobutyl ketone content (GC): 6.4% by mass Viscosity (80°C, rotational viscometer, shear rate = 10 / s): 17.6 Pa·s Acid value (based on solids): 17.1 mg KOH / g Number average molecular weight (VPO): 3500g / mol.

[0129] Example D1 Preparation of an aqueous polyurethane-polyurea dispersion Organic phase (I) P1 was charged into an addition tank at 82°C under a nitrogen overpressure of 5.5 bar and then continuously fed via a gear pump to a high-shear disperser equipped with a rotor / stator unit through a stainless steel pipe at a mass flow rate of 7.671 kg per hour. The transfer pipe was insulated and heated to 82°C. Aqueous phase (II), consisting of a 0.639% by weight sodium hydroxide (Merck) solution in deionized water, was fed to a second addition tank at 5°C and continuously fed to the high-shear disperser equipped with a rotor / stator unit through another pipe at a mass flow rate of 8.284 kg per hour using an eccentric screw pump. Both dosing operations were stopped after 23 minutes and 28 seconds. By that time, 3000.0 g of organic phase (I) and 3239.9 g of aqueous phase (II) had been fed. Throughout the entire process, the above-mentioned mass flow rates of the two phases ensured a degree of neutralization of 65% (first neutralization step).

[0130] The two streams were fed in parallel (i.e., simultaneously) and combined within the rotor / stator unit, rather than before reaching it. More specifically, the two streams, and therefore the phases, were primarily combined within the stator subunit, as shown in Figure 1. Thus, the aqueous phase (II) was fed through a centrally located first inlet (13), and the organic phase (I) was fed in the form of multiple sub-feed streams through multiple second inlets (14). The high-shear dispersing device was based on a Hagen & Funke Cavitron CD 1010 rotor / stator dispenser. In this setup, the cylindrical stator subunit with the central inlet (13) was further equipped with 24 drilled holes (i.e., multiple inlets (14)) with an inner diameter of 2 mm, arranged in a circular pattern and spaced at uniform distances from one another. The stator subunits had three sets of stator teeth (11) (inner diameters: I-35.2 mm, II-52.5 mm, and III-63.5 mm) with different numbers of teeth (12) (I-24, II-34, and III-160). Therefore, the drill holes were positioned between two sets of stator teeth (i.e., between the set with the smallest diameter and the set with the intermediate diameter), as shown in Figure 1. The cylindrical rotor subunits had four sets of rotor teeth (21) with different numbers of teeth (22) (I-12, II-28, III-70, and IV-160). The rotor teeth were alternated with the stator teeth, as shown in Figure 3, and the rotor was rotatable at a maximum speed of 12,000 rpm.

[0131] The high viscosity organic-based phase (I) and the low viscosity aqueous phase were intensively dispersed under high shear by passing through the inlet and grooves between the partially rotating set of teeth of the stator and rotor. The resulting dispersion was discharged through an outlet located at the tip of the outermost set of rotor teeth. The rotor / stator unit was fully jacketed and internally cooled to reduce the temperature of the discharged dispersion, which was approximately 55°C.

[0132] Chain extension was performed using a T-joint injector. The aqueous dispersion discharged from the high-shear disperser was continuously passed through a separate piping system connected to one arm of the T-joint, and the chain extender was continuously fed through the second arm of the T-joint. More specifically, the chain extender was continuously fed as an aqueous solution (8.0 wt.% diethylenetriamine in deionized water) using a double piston pump at a mass flow rate of 0.971 kg per hour (again, a total of 379.7 g of aqueous amine was fed in 23 minutes and 28 seconds). Downstream of the T-joint, a static mixer was used to effectively mix the polyurethane dispersion and the chain extender amine. During the entire process, the mass flows of the aqueous dispersion and diethylenetriamine aqueous solution discharged from the high-shear disperser ensured a molar ratio of the isocyanate groups of the polyurethane-based dispersion (calculated as the isocyanate groups contained in the prepolymer of the organic phase (I)) to the sum of the primary amino groups and secondary amino groups of the chain extender (calculated from the respective diethylenetriamine concentrations in the aqueous solution) of 1.62: 1. The time (residence time) from when the aqueous dispersion left the high-shear disperser to when the chain extender was supplied / added was calculated to be 6.7 seconds.

[0133] In the following, the different relevant parameters of the above-mentioned process are summarized once again, and the characteristics of the aqueous polyurethane-polyurea dispersion D1 produced are listed: Mass flow rate of organic phase (I): 7.671 kg per hour Mass flow rate of aqueous phase (II): 8.284 kg per hour Mass flow rate of aqueous solution of chain extender: 0.971 kg per hour Mass flow rate of polyurethane-polyurea dispersion (total): 16.926 kg per hour Pipe inner diameter from high shear disperser to chain extender injection point (T-joint): 12 mm Distance from the outlet of the high shear disperser to the chain extender addition point (T-joint): 27.4 cm Density of the aqueous dispersion (60°C) discharged from the high shear disperser: 1.024 g / cm 3 Residence time: 6.7s Rotor speed: 12000 rpm Temperature of the organic phase (I) at the inlet of the high shear disperser: 82°C Temperature of the aqueous dispersion discharged from the high shear disperser when it reached the T-joint: 54°C Solid content (130℃, 60 minutes, 1g): 40.2% by mass Dipropylene glycol dimethyl ether (GC): 3.0% by mass Methyl isobutyl ketone-Gehardt (GC): 2.9% by mass Viscosity (23°C, undiluted solution, rotational viscometer, shear rate = 1000 / s): 16 mPa·s Acid value: 17.6 mg KOH / g solids MEQ base: 0.257 mmol / g solids Neutralization level: 82% pH(23℃):7.7 Particle size parameters (Photon Correlation Spectroscopy): Volume average particle size (i.e., volume-based average diameter): 181 nm Average particle size: 177nm Gel fraction (130 ° C): 98.8% by mass Gel fraction (lyophilized): 98.5% by mass.

[0134] The aqueous polyurethane-polyurea dispersion D1 produced had excellent storage stability. This dispersion was well suited for application to base coat compositions, such as automotive base coat compositions. Therefore, this dispersion can be easily used to provide multi-coat coating systems that include base coat compositions and also base coat films produced by such base coat compositions. Specifically, this dispersion resulted in significantly improved yellowing behavior (i.e., coatings such as multi-coat coating systems that include coating layers based on aqueous base coat compositions containing this dispersion exhibit a significantly lower tendency to continuous yellowing, ultimately resulting in improved optical quality levels).

[0135] Example D2 Preparation of an aqueous polyurethane-polyurea dispersion As with Example D1, the preparation of aqueous polyurethane-polyurea dispersion D2 again involved the same overall general procedure as Example D1 in terms of the characteristics of the high shear disperser, with deviations particularly in the selection of the neutralizing agent.

[0136] More specifically, organic phase (I) P1 was charged into an addition tank at 82°C under a nitrogen overpressure of 5.5 bar and then continuously fed via a gear pump to a high-shear disperser equipped with a rotor / stator unit through a stainless steel pipe at a mass flow rate of 7.004 kg per hour. The transfer pipe was insulated and heated to 82°C. Aqueous phase (II), consisting of a 0.383 wt.% lithium hydroxide (Merck) solution in deionized water, was fed to a second addition tank at 5°C and continuously fed to the high-shear disperser equipped with a rotor / stator unit through another pipe at a mass flow rate of 7.554 kg per hour using an eccentric screw pump. Both dosing operations were stopped after 25 minutes and 42 seconds. By that time, 3000.0 g of organic phase (I) and 3235.9 g of aqueous phase (II) had been fed. Throughout the entire process, the above-mentioned mass flow rates of the two phases ensured a degree of neutralization of 65% (first neutralization step).

[0137] The two streams were fed, combined and dispersed as described in Example D1. The rotor / stator unit was again fully jacketed and internally cooled to reduce the temperature of the exiting dispersion.

[0138] Similarly, chain extension was also carried out through the T-joint injector. The aqueous dispersion discharged from the high-shear disperser was continuously passed through a piping system connected to one arm of the T-joint, and the chain extender was continuously supplied through the second arm of the T-joint. More specifically, the chain extender was continuously supplied as an aqueous solution (8.0 wt.% diethylenetriamine in deionized water) using a double piston pump at a mass flow rate of 0.887 kg per hour (a total of 379.7 g of aqueous amine solution was supplied over 25 minutes and 42 seconds). Downstream of the T-joint, a static mixer was again used to effectively mix the polyurethane dispersion and the chain-extending amine. The molar ratio of the isocyanate groups of the polyurethane base dispersion (calculated as the isocyanate groups contained in the prepolymer of the organic phase (I)) to the sum of the primary and secondary amino groups of the chain extender (calculated from the respective diethylenetriamine concentrations in the aqueous solution) was maintained at 1.62:1. The time from when the aqueous dispersion exited the high shear disperser to when the chain extender was fed / added (residence time) was calculated to be 7.4 seconds.

[0139] The continuously produced aqueous polyurethane-polyurea dispersion was collected in a collection vessel and cooled to 23°C. 32.4 g of a 10% by weight lithium hydroxide solution in deionized water was added under stirring to a degree of neutralization of 82% (second neutralization step). A white, stable, solids-rich, low-viscosity dispersion containing crosslinked particles was obtained, and no settling was observed within 12 months.

[0140] In the following, the different relevant parameters of the above-mentioned process are summarized once again, and the characteristics of the aqueous polyurethane-polyurea dispersion D2 produced are listed: Mass flow rate of organic phase (I): 7.004 kg per hour Mass flow rate of aqueous phase (II): 7.554 kg per hour Mass flow rate of aqueous solution of chain extender: 0.887 kg per hour Mass flow rate of polyurethane-polyurea dispersion (total): 15.445 kg per hour Pipe inner diameter from high shear disperser to chain extender injection point (T-joint): 12 mm Distance from the outlet of the high shear disperser to the chain extender addition point (T-joint): 27.4 cm Density of the aqueous dispersion (60°C) discharged from the high shear disperser: 1.024 g / cm 3 Residence time: 7.4s Rotor speed: 12000 rpm Temperature of the organic phase (I) at the inlet of the high shear disperser: 82°C Temperature of the aqueous dispersion discharged from the high shear disperser when it reached the T-joint: 55°C Solid content (130℃, 60 minutes, 1g): 40.0% by mass Dipropylene glycol dimethyl ether (GC): 2.9% by mass Methyl isobutyl ketone-Gehardt (GC): 2.9% by mass Viscosity (23°C, undiluted solution, rotational viscometer, shear rate = 1000 / s): 21 mPa·s Acid value: 18.5 mg KOH / g solids MEQ base: 0.264 mmol / g solids Neutralization level: 80% pH(23℃):7.6 Particle size parameters (Photon Correlation Spectroscopy): Volume average particle size (i.e., volume-based average diameter): 174 nm Average particle size: 178nm Gel fraction (130 ° C): 96.9% by mass Gel fraction (lyophilized): 96.0% by mass.

[0141] The aqueous polyurethane-polyurea dispersion D2 produced had excellent storage stability. This dispersion was well suited for application to base coat compositions, such as automotive base coat compositions. Therefore, this dispersion can be easily used to provide multi-coat coating systems that include base coat compositions and also base coat films produced by such base coat compositions. Specifically, this dispersion resulted in significantly improved yellowing behavior (i.e., coatings such as multi-coat coating systems that include coating layers based on aqueous base coat compositions containing this dispersion exhibit a significantly lower tendency to continuous yellowing, ultimately resulting in improved optical quality levels).

[0142] Example V1 Preparation of an aqueous polyurethane-polyurea dispersion As in Example D1, the preparation of aqueous polyurethane-polyurea dispersion V1 again involved the same overall general procedure as in Example D1, with deviations particularly in the selection of the neutralizing agent, with the characteristics of the high shear dispersing equipment (such as drill holes).

[0143] Organic phase (I) P1 was charged into an addition tank at 82°C under a nitrogen overpressure of 5.5 bar and then continuously fed via a gear pump to a high-shear disperser equipped with a rotor / stator unit through a stainless steel pipe at a mass flow rate of 7.600 kg per hour. The transfer pipe was insulated and heated to 82°C. Aqueous phase (II), consisting of a 2.056 wt.% solution of triethylamine TEA (BASF SE) in deionized water, was fed to a second addition tank at 5°C and continuously fed to the high-shear disperser equipped with a rotor / stator unit through another pipe at a mass flow rate of 8.341 kg per hour using an eccentric screw pump. Both dosing operations were stopped after 23 minutes and 41 seconds. By that time, 3,000.0 g of organic phase (I) and 3,292.2 g of aqueous phase (II) had been fed. Throughout the entire process, the mass flow rates of the two phases ensured a neutralization degree of 84%.

[0144] The two streams were fed, combined and dispersed as described in Example D1. The rotor / stator unit was again fully jacketed and internally cooled to reduce the temperature of the exiting dispersion.

[0145] Chain extension was also performed via the T-joint injector. The aqueous dispersion discharged from the high-shear disperser was continuously passed through a separate piping system connected to one arm of the T-joint, and the chain extender was continuously fed through the second arm of the T-joint. More specifically, the chain extender was continuously fed as an aqueous solution (8.0 wt.% diethylenetriamine in deionized water) using a double piston pump at a mass flow rate of 0.962 kg per hour (again, a total of 379.7 g of aqueous amine solution was fed in 23 minutes and 41 seconds). Downstream of the T-joint, a static mixer was used to effectively mix the polyurethane dispersion and the chain-extending amine. During the entire process, the mass flow rates of the aqueous dispersion and diethylenetriamine aqueous solution discharged from the high-shear disperser were such that the molar ratio of the isocyanate groups of the polyurethane-based dispersion (calculated as the isocyanate groups contained in the prepolymer of the organic phase (I)) to the total of the primary and secondary amino groups of the chain extender (calculated from the respective diethylenetriamine concentrations in the aqueous solution) was 1.62: 1. The time (residence time) from when the aqueous dispersion left the high-shear disperser to when the chain extender was supplied / added was calculated to be 6.8 seconds.

[0146] Below we summarize again the different relevant parameters of the above process: Mass flow rate of organic phase (I): 7,600 kg per hour Mass flow rate of aqueous phase (II): 8.341 kg per hour Mass flow rate of aqueous solution of chain extender: 0.962 kg per hour Mass flow rate of polyurethane-polyurea dispersion (total): 16.903 kg per hour Pipe inner diameter from high shear disperser to chain extender injection point (T-joint): 12 mm Distance from the outlet of the high shear disperser to the chain extender addition point (T-joint): 27.4 cm Density of the aqueous dispersion (60°C) discharged from the high shear disperser: 1.024 g / cm 3 Residence time: 6.8s Rotor speed: 12000 rpm Temperature of the organic phase (I) at the inlet of the high shear disperser: 82°C Temperature of the aqueous dispersion discharged from the high shear disperser when it reached the T-joint: 50°C.

[0147] The continuously produced aqueous polyurethane-polyurea dispersion was collected in a collection vessel and cooled to 23° C. A white, stable, solids-rich, low-viscosity dispersion containing crosslinked particles was obtained, with no precipitation observed within 6 months.

[0148] The properties of the aqueous polyurethane-polyurea dispersion V1 produced were as follows: Solid content (130℃, 60 minutes, 1g): 40.1% by mass Dipropylene glycol dimethyl ether (GC): 3.0% by mass Methyl isobutyl ketone-Gehardt (GC): 2.9% by mass Viscosity (23°C, undiluted solution, rotational viscometer, shear rate = 1000 / s): 39 mPa·s Acid value: 17.1 mg KOH / g solids MEQ base: 0.256 mmol / g solids Neutralization rate: 84% pH(23℃):7.6 Particle size parameters (laser diffraction): d(0,1):0.5μm D[3,2]: 0.7 μm d(0,5):0.8μm D[4,3] (i.e., volume-based mean diameter): 1.1 μm d(0,9):1.5μm Gel fraction (130 ° C): 88.9 mass% Gel fraction (lyophilized): 87.3% by mass.

[0149] Example V2 Preparation of an aqueous polyurethane-polyurea dispersion As with Example D1, the preparation of aqueous polyurethane-polyurea dispersion V2 again involved the same overall general procedure as Example D1, with deviations particularly in the selection of the neutralizing agent, with regard to the characteristics of the high shear dispersing equipment (such as drill holes).

[0150] The organic phase (I) P1 was charged into an addition tank at 82°C under a nitrogen overpressure of 5.5 bar and then continuously fed via a gear pump to a high-shear disperser equipped with a rotor / stator unit through a stainless steel pipe at a mass flow rate of 7.171 kg per hour. The transfer pipe was insulated and heated to 82°C.

[0151] A second addition tank contained an aqueous phase (II) consisting of a 2.197% by weight solution of triethylenediamine TEDA (1,4-diazabisilo[2.2.2]octane, manufactured by BASF SE) in deionized water at 5°C. Using an eccentric screw pump, this was continuously fed to the rotor / stator high-shear disperser through a separate pipe at a mass flow rate of 8.166 kg per hour. Both dosing operations were stopped after 25 minutes and 6 seconds. By that time, 3,000.0 g of organic phase (I) and 3,416.3 g of aqueous phase (II) had been delivered. The mass flow rates of the two phases ensured a neutralization rate of 84% throughout the entire process.

[0152] The two streams were fed, combined and dispersed as described in Example D1. The rotor / stator unit was again fully jacketed and internally cooled to reduce the temperature of the exiting dispersion.

[0153] Similarly, chain extension was also performed via a T-joint injector. The aqueous dispersion discharged from the high-shear disperser was continuously passed through a separate piping system connected to one arm of the T-joint, and the chain extender was continuously fed through the second arm of the T-joint. More specifically, the chain extender was continuously fed as an aqueous solution (8.0 wt.% diethylenetriamine in deionized water) using a double piston pump at a mass flow rate of 0.908 kg per hour (again, a total of 379.7 g of aqueous amine solution was fed in 25 minutes and 6 seconds). Downstream of the T-joint, a static mixer was used to effectively mix the polyurethane dispersion and the chain-extending amine. During the entire process, the mass flows of the aqueous dispersion and diethylenetriamine aqueous solution discharged from the high-shear disperser ensured a molar ratio of the isocyanate groups of the polyurethane dispersion (calculated as the isocyanate groups contained in the prepolymer of the organic phase (I)) to the sum of the primary and secondary amino groups of the chain extender (calculated from the concentrations of each diethylenetriamine in the aqueous solution) of 1.62: 1. The time (residence time) from when the aqueous dispersion left the high-shear disperser to when the chain extender was supplied / added was calculated to be 7.0 seconds.

[0154] Below we summarize again the various relevant parameters of the process described above: Mass flow rate of organic phase (I): 7.171 kg per hour Mass flow rate of aqueous phase (II): 8.166 kg per hour Mass flow rate of aqueous solution of chain extender: 0.908 kg per hour Mass flow rate of polyurethane-polyurea dispersion (total): 16.245 kg per hour Pipe inner diameter from high shear disperser to chain extender injection point (T-joint): 12 mm Distance from the outlet of the high shear disperser to the chain extender addition point (T-joint): 27.4 cm Density of the aqueous dispersion (60°C) discharged from the high shear disperser: 1.024 g / cm 3 Dwell time: 7.0 seconds Rotor speed: 12000 rpm Temperature of the organic phase (I) at the inlet of the high shear disperser: 82°C Temperature of the aqueous dispersion discharged from the high shear disperser when it reached the T-joint: 52°C.

[0155] The continuously produced aqueous polyurethane-polyurea dispersion was collected in a collection vessel and cooled to 23° C. A white, stable, solids-rich, low-viscosity dispersion containing crosslinked particles was obtained, with no precipitation observed within 6 months.

[0156] The properties of the aqueous polyurethane-polyurea dispersion V1 produced were as follows: Solid content (130℃, 60 minutes, 1g): 39.8% by mass Dipropylene glycol dimethyl ether (GC): 2.9% by mass Methyl isobutyl ketone-Gehardt (GC): 2.9% by mass Viscosity (23°C, undiluted solution, rotational viscometer, shear rate = 1000 / s): 14 mPa·s Acid value: 17.5 mg KOH / g solids MEQ base: 0.259 mmol / g solids Neutralization level: 83% pH(23℃):7.4 Particle size parameters (Photon Correlation Spectroscopy): Volume average particle size (i.e., volume-based average diameter): 540 nm Average particle size: 666nm Gel fraction (130 ° C): 90.3 mass% Gel fraction (lyophilized): 87.7% by mass.

[0157] The dispersions prepared above were used to prepare binder yellowing test compositions BYTC, which contained a minor portion of the Na-Li-Mg-silicate clay with dispersion, thus polyurethane-polyurea polymer, water, and polypropylene glycol.

[0158] First, a wet film of BYTC was applied to a glass plate or a white primer-coated aluminum panel using a 150- or 250-micrometer doctor blade. The wet film was dried at 60°C for 10 minutes and then baked at 160°C for 60 minutes (160°C overbake test). The unpigmented film was clear and contained only the polymer from the dispersion, plus low levels of clay and polypropylene glycol.

[0159] The yellowness index YI of the baked film (1 layer) on a glass plate was measured by transmission using a spectrophotometer. For aluminum panels coated with a white primer, the b* value of the baked BYTC (2 layers) was measured by reflection spectrophotometer and compared with a triethylamine neutralized reference (V1). A negative delta b* value indicates bluer tint, while a positive value indicates yellower tint than the reference, indicating yellowing.

[0160] Table 1 summarizes the results and data.

[0161] [Table 1]

[0162] (1) Deionized water contains 3.0% by mass of Laponite® RD (manufactured by Byk) and 3.0% by mass of polypropylene glycol 900 (Pluriol® P 900 C manufactured by BASF SE).

[0163] (2) Dry at 60℃ for 10 minutes, then bake at 160℃ for 60 minutes.

[0164] 3 The Yellowness Index YI is calculated from spectrophotometric data that represent the color change of the test sample from clear or white to yellow. The baked coating system on a glass plate was measured using a UV-VIS spectrophotometer (Cary 5000) from Agilent. The tristimulus values ​​X, Y, and Z were measured in the spectral range of 700-400 nm. To avoid radiation losses due to dispersion in the detector, an integrating sphere (Ulbricht globe) (Labshere 110 nm from Varian) was used. According to ASTM E313-15, the Yellowness Index YI was calculated from the following formula: YI=100×(C x XC z Z) / Y (In the formula, C x and C z is the coefficient for a viewing angle of 10° using the lighting techniques CIE Illuminant C and CIE Illuminant D65. CIE Illuminant C and CIE Illuminant D65 represent average daylight, which has a color temperature of approximately 6500 K.

[0165] 4 CIE Illuminant C represents average daylight with a color temperature of 6774 K.

[0166] 5 CIE illuminant D65 represents average daylight with a color temperature of 6504 K.

[0167] The white water-based BASF primer FU200201 (Frozen white) on 6 Al panels is baked for 20 minutes at a panel temperature of 160°C before applying a second layer based on the binder yellowing test composition BYTC containing the polymers of dispersions D1, D2, V1 and V2.

[0168] 7. Binder Yellowing Test: Color data for a two-layer coating of a white primer surfacer (BASF Primer Frozen White FU200201) with a second layer based on the BYTC composition was determined using a Byk Mac I spectrophotometer (manufactured by Byk Gardner GmbH). The light sources were D65 (observer angle 10°), A (observer angle 10°), and TL84 (observer angle 10°). Using the aforementioned equipment, the L*, a*, and b* values ​​of the two-layer film were measured. Values ​​on the b* axis of the CIELAB color space (ranging from blue to yellow) were recorded to characterize yellowing. A negative delta b* value indicates a more bluish color, while a positive value indicates a more yellowish color. A system with polyurea-urethane dispersion V1 neutralized with triethylamine was used as a color reference.

[0169] 8 CIE Illuminant A refers to a conventional incandescent lamp with a color temperature of 2856 K.

[0170] 9 CIE illuminant TL84 represents a European and Japanese commercial illuminant (supermarket lighting) with a color temperature of 4100K.

[0171] Dispersions D1 and D2 of the present invention show a significantly reduced Yellowness Index YI compared to the amine-neutralized dispersions, where triethylenediamine showed slightly reduced yellowing compared to triethylamine.

Claims

1. 1. An aqueous polyurethane-polyurea dispersion comprising polyurethane-polyurea particles having a volume-based average diameter of 50 to 500 nm, the dispersion being further characterized by an MEQ base of 0.125 to 0.625 meq / g (based on solids), whereby preparation of the dispersion comprises a neutralization step using at least one alkali metal hydroxide as a neutralizing agent.

2. 2. The aqueous polyurethane-polyurea dispersion of claim 1, wherein the MEQ base is from 0.15 to 0.50 meq / g (based on solids).

3. 3. The aqueous polyurethane-polyurea dispersion of claim 1, wherein the degree of neutralization of the aqueous polyurethane-polyurea dispersion is greater than 65%.

4. 3. The aqueous polyurethane-polyurea dispersion of claim 1, wherein the dispersion consists of at least 90% by weight of polyurethane-polyurea polymer and water (calculated as the sum of the proportion of water and the weight % solids of the dispersion).

5. 1. A method for continuously producing an aqueous polyurethane-polyurea dispersion comprising polyurethane-polyurea particles having a volume average diameter of from 50 to 500 nm, and further characterized by an MEQ base of from 0.125 to 0.625 meq / g (based on solids), comprising the steps of: (1) the following ingredients: (a) at least one acid-functional polyurethane prepolymer containing isocyanate groups; and (b) 0 to 20% by weight, based on the total weight of the organic-based phase (I), of at least one organic solvent; providing an organic-based phase (I) comprising (2) providing an aqueous phase (II); (3) continuously feeding both the organic-based phase (I) and the aqueous phase (II) into a high shear dispersing device comprising a rotor / stator unit; (3.1) the organic-based phase (I) and the aqueous phase (II) are contacted in the rotor / stator unit, rather than before reaching the rotor / stator unit; and (3.2) the organic phase (I) is fed to the rotor / stator unit via multiple inlets in the form of multiple sub-feed streams, (4) continuously dispersing the organic-based phase (I) and the aqueous phase (II) in the rotor-stator unit, thereby producing an aqueous polyurethane-based dispersion; (5) continuously discharging the aqueous polyurethane-based dispersion from the high shear disperser, thereby forming a volumetric flow of dispersion; and (6) providing at least one chain extender to the aqueous polyurethane-based dispersion, thereby producing an aqueous polyurethane-polyurea dispersion. Including, The method, wherein a neutralization step using at least one alkali metal hydroxide as a neutralizing agent is carried out during the dispersion process according to the above steps (3) and (4).

6. 6. The method according to claim 5, wherein two neutralization steps using at least one alkali metal hydroxide as a neutralizing agent are carried out, the first neutralization step being carried out during the dispersion process according to steps (3) and (4), and the second neutralization step being carried out after the dispersion process according to steps (3) and (4), wherein the degree of neutralization achieved in the first neutralization step is 50 to 70%, and the degree of neutralization achieved in the second neutralization step is greater than 70 to 95% (as the sum of the first and second neutralization steps).

7. 7. The method of claim 6, wherein the first neutralization step is carried out at a temperature of 40 to 70°C and the second neutralization step is carried out at a temperature of 10 to 30°C.

8. 6. The method according to claim 5 or the dispersion according to claim 1, wherein the chain extender is selected from aliphatic, aromatic, or araliphatic (mixed aliphatic-aromatic) polyamines containing at least two primary and / or secondary amino groups, preferably triamines having a total of three amino groups selected from primary and secondary amino groups.

9. 6. The method of claim 5, wherein the time between when the dispersion exits the high shear disperser and when the chain extender is fed is 30 seconds or less.

10. 6. The method of claim 5 or the dispersion of claim 1, wherein the polyurethane-polyurea particles in the aqueous polyurethane-polyurea dispersion produced are characterized by a gel fraction of at least 70%.

11. 10. An aqueous basecoat composition comprising the aqueous polyurethane-polyurea dispersion of claim 1 and / or the aqueous polyurethane-polyurea dispersion prepared according to claim 5.

12. 12. The aqueous basecoat composition of claim 11, further comprising at least one hydroxy-functional polymer different from the melamine resin and the polymer present in the aqueous dispersion.

13. (1) applying an aqueous basecoat composition to a substrate; (2) forming a polymeric film from the coating material applied in step (1); (3) applying a clear coat material to the resulting base coat film, and then (4) Curing the base coat film together with the clear coat film 1. A method for manufacturing a multi-coat paint system comprising: The method of claim 11, wherein the water-borne basecoat material used in step (1) is the basecoat composition of claim 11.

14. A multi-coat paint system produced by the method of claim 13.

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