Hydrophilic polyisocyanates based on 1,5-diisocyanatopentane with reduced viscosity

Abstract

The invention relates to a coating composition comprising a polyisocyanate composition based on 1,5-diisocyanatopentane with reduced viscosity, to a process for the preparation thereof, to coatings obtainable by the use thereof, and to the use of the polyisocyanate composition.

Description

[0001] Hydrophilic polyisocyanates based on 1,5-diisocyanatopentane with reduced viscosity

[0002] The invention relates to a coating material comprising a polyisocyanate composition based on 1,5-diisocyanatopentane with reduced viscosity, a process for its production, coatings obtainable by its use, and the use of the polyisocyanate composition.

[0003] Water-based coating systems have become firmly established today as an environmentally friendly alternative to solvent-based coatings in various applications. Hydrophilic-modified polyisocyanates play a particularly important role as raw materials for high-quality water-based coatings, as they enable the formulation of water-dispersible binder components for two-component (2K-PUR) water-based coatings.

[0004] Hydrophilic polyisocyanates can be stirred into aqueous paint binder dispersions in a fine and homogeneous manner without the use of high shear forces, which positively influences application reliability and optical properties, especially gloss and transparency of the resulting coatings.

[0005] The trend towards more sustainable products has led to an increasing demand for bio-based raw materials in the polyurethane sector in recent years. This prompted the development of polyisocyanate vemets based on 1,5-diisocyanatopentane (also known as "pentamethylene diisocyanate" or "PDI"), which is accessible from biomass (see, for example, EP-A 3 271 432 and WO 2016 / 169810). Hydrophilic polyisocyanate vemets based on PDI are also already known.

[0006] WO 2016 / 146579, for example, describes a very broad range of hydrophilic polyisocyanate compositions comprising a PDI polyisocyanate component and at least one ionic and / or nonionic emulsifier. Of particular interest are those polyisocyanate compositions with nonionic emulsifiers that can be obtained simply and inexpensively by partial urethanization of hydrophobic PDI polyisocyanates with hydrophilic polyether monoalcohols. However, unlike the present invention, the polyisocyanate compositions disclosed therein either contain polyether monoalcohols bound via allophanate structures or no polyether monoalcohols of the molecular weight range according to the invention.

[0007] The subject of JP 2020007450 is the reaction products of low-viscosity PDI polyisocyanurates containing allophane groups with polyether monoalcohols, exhibiting viscosities at 25 °C in the range of > 300 mPa s, preferably > 800 mPa s to < 2000 mPa s. The viscosities of the PDI polyisocyanurates containing allophane groups used as starting materials are not disclosed.

[0008] CN 110183618 describes a one-pot process for the production of nonionic aqueous crosslinkers by distillative purification and reaction of bio-pentamethylene diisocyanate trimers with polyether polyols, such as methoxypolyethylene glycols. Information on the synthesis of the PDI trimers used and their key parameters, such as NCO content and viscosity, is missing. Based on the NCO contents of the process products mentioned in the examples and their composition, NCO contents of 23.0 to 24.2 wt% can be calculated for the bio-pentamethylene diisocyanate trimers.

[0009] Generally, low viscosity facilitates the dispersibility of hydrophilic polyisocyanates in aqueous systems. In the production of polyisocyanurate polyisocyanates, which typically occurs via the catalytic trimerization of diisocyanates, the reaction must be terminated at low conversion levels to obtain particularly low-viscosity products. Due to the resulting high proportion of ideal isocyanurate trimer (n = 3), consisting of three diisocyanate molecules, polyisocyanurate polyisocyanates produced in this way are indeed low-viscosity, but simultaneously exhibit only low average isocyanate functionalities.

[0010] However, low isocyanate functionality is a disadvantage when used as a veneer component for coatings, as it leads to a lower veneer density and thus lower resistance properties.

[0011] For the production of hydrophilic polyisocyanates, the highest possible functionality of the starting polyisocyanate is also desirable, since modification reactions, such as urethanization with a hydrophilic polyether alcohol, are always associated with a reduction in functionality.

[0012] The object of the present invention was therefore to provide new non-ionically hydrophilically modified PDI polyisocyanates, in particular those with polyisocyanurate structure, with high functionality and simultaneously low viscosity, which are suitable for all application areas of water-dispersible polyisocyanates.

[0013] As has now been surprisingly discovered, reaction products of highly viscous, highly functional PDI polyisocyanurates, which were produced with a high degree of trimerization and therefore exhibit comparatively high proportions of isocyanurate pentamers (n = 5) and higher oligomers or comparatively low proportions of ideal isocyanurate trimer (n = 3), with methoxypolyethylene glycols of a narrowly defined molecular weight range show significantly lower viscosities than the starting polyisocyanates and at the same time possess excellent dispersibility in aqueous systems.

[0014] The invention relates to a coating composition comprising a polyisocyanate composition, comprising at least one polyisocyanurate polyisocyanate A) based on 1,5-diisocyanatopentane, having a number-average molecular weight of at least 680 g / mol and a weight ratio of isocyanurate trimer to isocyanurate pentamer of less than 2.2, and an emulsifier component B), comprising a urethane obtainable by urethanization of a polyisocyanurate polyisocyanate A) with a hydrophilic polyether monoalcohol having a number-average molecular weight of 400 to 600 g / mol, wherein at least 60 wt%, based on the total amount of the hydrophilic polyether monoalcohol, of the hydrophilic polyether monoalcohol is not bound to the polyisocyanurate polyisocyanate A) via allophanate groups, and wherein the number-average molecular weight can in each case be determined by gel permeation chromatography as described above.

[0015] at least one binder component, which preferably comprises at least one compound reactive towards isocyanate groups, as well as

[0016] Possibly other auxiliary and additive substances.

[0017] Preferably, the amount of the polyether monoalcohol not bound to the polyisocyanurate polyisocyanate A) via allophanate groups is at least 70 wt.%, more preferably at least 75 wt.%, even more preferably at least 85 wt.%, most preferably at least 90 wt.%, in each case based on the total amount of the hydrophilic polyether monoalcohol.

[0018] The invention also relates to a process for producing this coating agent comprising hydrophilically modified polyisocyanate compositions containing polyisocyanurate polyisocyanates, and its use in the production of polyurethane plastics, in particular comprising the polyisocyanate compositions as crosslinkers for water-soluble or water-dispersible paint binders or paint binder components with groups reactive towards isocyanate groups.

[0019] Within the scope of this invention, “polyisocyanurate polyisocyanate based on diisocyanate X” means that the polyisocyanurate polyisocyanate comprises trimers of diisocyanate X. Trimers of other diisocyanates may also be included in the polyisocyanurate polyisocyanate.

[0020] The polyisocyanurate polyisocyanate based on 1,5-diisocyanatopentane, contained in or used according to the invention, is described in more detail below, and it is clear that the described embodiments of the polyisocyanurate polyisocyanate can be used in the invention, the invention process, the invention use, and the invention coatings.

[0021] In a preferred embodiment, the polyisocyanurate polyisocyanate consists of oligomers of 1,5-diisocyanatopentane.

[0022] According to the invention, the number-mean molecular weight (Mn) of a polyisocyanate is determined using software-assisted gel permeation chromatography (GPC) at 23 °C in tetrahydrofuran as the solvent. The measurement is performed according to DIN 55672-1:2016-03 "Gel permeation chromatography, Part 1 - Tetrahydrofuran as eluent". The weight ratio of isocyanurate trimer (n = 3) to isocyanurate pentamer (n = 5) is obtained from the ratio of the respective area percentages taken from the chromatograms of the aforementioned GPC method, which were approximated as weight fractions.

[0023] Within the scope of this invention, the terms "comprising" or "containing" preferably mean "essentially consisting of" and particularly preferably "consisting of". The further embodiments mentioned in the claims and in the description can be combined arbitrarily, unless the context clearly indicates otherwise.

[0024] “At least one,” as used herein, refers to one or more, for example, two, three, four, five, six, seven, eight, nine, or more. In the context of constituents of the compounds described herein, this term refers not to the absolute quantity of molecules, but to the type of constituent.

[0025] Numerical values ​​given herein without decimal places refer to the full value given with one decimal place. For example, "99%" means "99.0%".

[0026] Numeric ranges specified in the format "in / from x to y" include the stated values ​​x and y. If multiple preferred numeric ranges are specified in this format, it is understood that all ranges resulting from the combination of the different endpoints are also included.

[0027] In this context, the term "aliphatic" is defined as non-aromatic hydrocarbon groups that are saturated or unsaturated.

[0028] The term "linearaliphatic" refers to compounds that are completely free of cyclic structural elements, while the terms "alicyclic" or "cycloaliphatic" are defined as potentially substituted, carbocyclic or heterocyclic compounds or units that are non-aromatic (such as cycloalkanes, cycloalkenes, or oxa-, thia-, aza-, or thiazacycloalkanes). Specific examples include cyclohexyl groups, cyclopentyl groups, and their N- or O-heterocyclic derivatives, such as pyrimidine, pyrazine, tetrahydropyran, or tetrahydrofuran.

[0029] In the present case, the term "araliphatic" is defined as hydrocarbon residues that consist of both an aromatic and a saturated or unsaturated hydrocarbon group directly bonded to the aromatic residue.

[0030] In the event that the groups or compounds are disclosed as "optionally substituted" or "substituted", suitable substituents are -F, -Cl, -Br, -I, -OH, -OCHs, OCH2CH3, -O-isopropyl or -one-propyl, -OCF3, -CF3, -S-Ci-e-alkyl and / or (optionally via an attached heteroatom) a linear or branched, aliphatic and / or alicyclic structural unit with 1 to 12 carbon atoms, each acting as a replacement for a carbon-bound hydrogen atom of the molecule in question. Preferred substituents are halogen (in particular -F, -CI), C1-C6 alkoxy (in particular methoxy and ethoxy), hydroxy, trifluoromethyl and trifluoromethoxy, each acting as a replacement for a carbon-bound hydrogen atom of the molecule in question.

[0031] The hydrophilically modified polyisocyanate composition based on 1,5-diisocyanatopentane comprises at least one polyisocyanurate polyisocyanate A) and at least one urethane of a polyisocyanurate polyisocyanate A) with a hydrophilic polyether monoalcohol as a non-ionic emulsifier B). The non-ionic emulsifier B) may comprise, consist substantially of, or be composed of a urethane obtainable by urethanizing a polyisocyanurate polyisocyanate A) with a hydrophilic polyether monoalcohol having a number-average molecular weight of 400 to 600 g / mol, wherein the number-average molecular weight is determinable by gel permeation chromatography as specified in the description.

[0032] Polyisocyanurate polyisocyanates A), hereinafter also referred to as starting polyisocyanates A), for the preparation of the hydrophilic polyisocyanate composition, are any oligomeric polyisocyanurate polyisocyanates obtainable by catalytic trimerization of a diisocyanate comprising 1,5-diisocyanatopentane (PDI), having a number-average molecular weight (Mn) of at least 680 g / mol, preferably at least 700 g / mol, particularly preferably at least 720 g / mol and a weight ratio of isocyanurate trimer (n = 3) to isocyanurate pentamer (n = 5) of less than 2.2, preferably less than 2.0, particularly preferably less than 1.9.

[0033] The preparation of these polyisocyanates A) is carried out according to methods known per se for isocyanate trimerization, as described, for example, in J. Prakt. Chem. 336 (1994) 185-200, by reacting (oligomerizing) a portion of the isocyanate groups of the PDI to form polyisocyanate molecules consisting of at least two, preferably at least three, diisocyanate molecules, wherein the conversion (degree of oligomerization) is chosen in each case such that the oligomerization product corresponds to the above-mentioned specifications for number-mean molecular weight (Mn) and weight ratio of isocyanurate trimer (n = 3) to isocyanurate pentamer (n = 5). In the production of polyisocyanurate polyisocyanate A), the actual trimerization reaction is generally followed by a distillative or extractive separation of the unreacted monomeric PDI to values ​​of, for example, less than 1.0 wt.%, preferably less than 0.5 wt.%, particularly preferably less than 0.3 wt.%.-%, based on the total amount of oligomerized diisocyanate and monomeric diisocyanate.

[0034] Specific examples of oligomeric PDI polyisocyanurates can be found, for example, in EP-A 2684 867, JP 2010-121011, JP 2010-254764, and JP 2013-060542. The polyisocyanurate polyisocyanate A) may, in addition to isocyanurate structures, also exhibit other structures in minor amounts, such as uretdione, biuret, iminooxadiazindione, and / or oxadiazintrione structures.

[0035] The 1,5-diisocyanatopentane used to produce the polyisocyanurate polyisocyanate A) is accessible in various ways, for example by phosgenation in the liquid or gas phase or by a phosgene-free method, such as thermal urethane cleavage, starting from 1,5-diaminopentane obtained preferably biotechnologically by decarboxylation of the naturally occurring amino acid lysine.

[0036] If necessary, in the preparation of polyisocyanurate polyisocyanate A), in addition to 1,5-diisocyanatopentane, other diisocyanates with aliphatic, cycloaliphatic, araliphatic, and / or aromatically bonded isocyanate groups can be used. These are particularly those with a molecular weight in the range of 140 to 400 g / mol, such as 1,4-diisocyanatobutane, 1,6-diisocyanatohexane (HDI), 2-methyl-1,5-diisocyanatopentane, 1,5-diisocyanato-2,2-dimethylpentane, 2,2,4-, and so on.2,4,4-Trimethyl-1,6-diisocyanatohexane, 1,10-Diisocyanatodecane, 1,3- and 1,4-Diisocyanatocyclohexane, 2,4- and 2,6-Diisocyanato-1-methylcyclohexane, 1,3- and 1,4-Bis-(isocyanatomethyl)cyclohexane, 1-Isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (isophorone diisocyanate, IPDI), 4,4'-Diisocyana-todicyclohexylmethane, 2,4'-Diisocyanato-dicyclohexylmethane, 1-Isocyanato-1-methyl-4(3)isocyanato-methylcyclohexane, Bis-(isocyanato-methyl)norboman, 1,3- and 1,4-Bis(isocyanatomethyl)benzene (XDI), 1,3- and 1,4-Bis-(2-isocyanato-prop-2-yl)benzene (TMXDI), 2,4- and 2,6-Diisocyanatotoluene (TDI), 2,4'- and 4,4'-Diisocyanatodiphenylmethane (MDI), 1,5-Diisocyanatonaphthalene or any mixtures of such diisocyanates.

[0037] These diisocyanates, which may optionally be used in the production of the polyisocyanurate polyisocyanate A), are used, if at all, in quantities of up to 80 wt.%, preferably up to 50 wt.%, particularly preferably up to 20 wt.%, based on the total amount of diisocyanates used.

[0038] Any mixtures of PDI polyisocyanurates of different degrees of oligomerization are also suitable as polyisocyanurate polyisocyanate A), provided that the mixtures meet the above specifications for number-mean molecular weight (Mn) and weight ratio of isocyanurate trimer (n = 3) to isocyanurate pentamer (n = 5).

[0039] Preferred polyisocyanurate polyisocyanates A) for the preparation of the polyisocyanate composition are PDI polyisocyanurates with a mean NCO functionality of 3.3 to 5.0 and / or an isocyanate group content of 15.0 to 22.9 wt.%, determinable according to DIN EN ISO 11909:2007-05, and / or a viscosity at 23 °C of 6000 to 12000 mPas, determinable according to DIN EN ISO 3219:1994-10 at a shear rate of 250 s 1 Particularly preferred are PDI polyisocyanurates with a mean NCO functionality of 3.3 to 5.0, an isocyanate group content of 15.0 to 22.9 wt.%, determinable according to DIN EN ISO 11909:2007-05, and a viscosity at 23 °C of 6000 to 12000 mPas, determinable according to DIN EN ISO 3219:1994-10 at a shear rate of 250 s⁻¹. 1 .

[0040] Particularly preferred polyisocyanurate polyisocyanates A) are polyisocyanates containing isocyanurate structures, which are produced using PDI as the sole diisocyanate and have a mean NCO functionality of 3.4 to 5.0, preferably 3.5 to 4.5, an isocyanate group content of 17.0 to 22.9 wt.%, preferably 19.0 to 22.5 wt.%, determinable according to DIN EN ISO 11909:2007-05, and a viscosity at 23 °C of 7000 to 11000 mPas, preferably 8000 to 10000 mPas, determinable according to DIN EN ISO 3219: 1994-10 at a shear rate of 250 s''.

[0041] The hydrophilically modified polyisocyanate composition based on 1,5-diisocyanatopentane contains, in addition to polyisocyanurate polyisocyanate A), at least one urethane of polyisocyanurate polyisocyanate A) with a hydrophilic polyether monoalcohol of average molecular weight 400 to 600 g / mol as a non-ionic emulsifier B). It is conceivable that the non-ionic emulsifier B), if the polyisocyanurate polyisocyanate A) is a mixture of different components such as diisocyanate trimers and diisocyanate pentamers,

[0042] only urethanes of one component,

[0043] Urethanes of several, but not all, components, or

[0044] Urethanes of all components of the polyisocyanurate polyisocyanate A) are present.

[0045] Suitable hydrophilic polyether monoalcohols are any polyalkylene oxide polyether monoalcohols, preferably monohydric, containing on average 8.5 to 13 ethylene oxide units per molecule, such as can be obtained in a manner known per se by alkoxylation of suitable starter molecules (see, e.g., Ullmann's Encyclopedia of Industrial Chemistry, 4th edition, Volume 19, Verlag Chemie, Weinheim, pp. 31–38). Such starter molecules can be, for example, any monohydric alcohols with a molecular weight in the range of 32 to 74 g / mol, such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, or sec-butanol.

[0046] Suitable alkylene oxides for the alkoxylation reaction are ethylene oxide and propylene oxide, which can be used in any order or as a mixture in the alkoxylation reaction. Suitable polyether monoalcohols are either pure polyethylene oxide polyether monoalcohols or mixed polyalkylene oxide polyethers whose alkylene oxide units consist of at least 80 mol%, preferably at least 90 mol%, of ethylene oxide units. Preferred polyalkylene oxide polyether monoalcohols are those prepared using methanol as a starter molecule. Particularly preferred polyether monoalcohols are pure polyethylene glycol monomethyl ether alcohols, which have, on average, 8.5 to 13, particularly preferably 9 to 12, and most preferably 10 to 11 ethylene oxide units.

[0047] In one embodiment, the hydrophilic polyether monoalcohol is obtained by alkoxylation of a monohydric alcohol having a molecular weight of 32 to 74 g / mol and has, on average, 8.5 to 13 ethylene oxide units per molecule.

[0048] The production of such preferred non-ionic emulsifiers B) is known in principle and is described, for example, in EP-B 0206059 and EP-B 0540985.

[0049] The invention also relates to a method for producing the coating agent according to the invention, characterized in that the polyisocyanurate polyisocyanate A) is mixed with the emulsifier component B) to obtain the polyisocyanate composition, or the polyisocyanate composition is obtained by partial reaction of polyisocyanates of the polyisocyanurate polyisocyanate A) with the hydrophilic polyether monoalcohol, and the obtained polyisocyanate composition is mixed with the binder component and optionally with auxiliary and additive substances.

[0050] The production of the polyisocyanate composition in the process according to the invention can therefore be carried out by reacting the polyisocyanurate polyisocyanate A) with the aforementioned polyether monoalcohols either in a separate reaction step with subsequent mixing of the resulting emulsifier B) with the polyisocyanurate polyisocyanate A) to be converted into a hydrophilic form, or by mixing the polyisocyanurate polyisocyanate A) with a corresponding amount of the polyether monoalcohols, whereby a hydrophilic polyisocyanate mixture according to the invention is spontaneously formed under urethanization, which contains, in addition to unreacted polyisocyanurate polyisocyanate A), the emulsifier B) which is formed in situ from the polyether monoalcohol and a part of component A).

[0051] The reaction of the polyisocyanurate polyisocyanate A) with the polyether monoalcohols to form the nonionic emulsifiers B) generally takes place at temperatures of 40 to 180 °C, preferably 50 to 150 °C, and / or while maintaining an NCO / OH equivalent ratio of 2:1 to 400:1, preferably 4:1 to 140:1.

[0052] In the first variant of the separate preparation of the nonionic emulsifiers B), these are preferably produced while maintaining an NCO / OH equivalent ratio of 2:1 to 6:1. In the in-situ preparation of the emulsifiers B), a high excess of isocyanate groups within the aforementioned broad range can, of course, be used. Regardless of the type of emulsifier B) and its preparation, its quantity, or the quantity of the polyether monoalcohol added to the polyisocyanurate polyisocyanates A) in an in-situ preparation of the emulsifier, is generally determined such that the resulting hydrophilically modified polyisocyanate composition based on 1,5-diisocyanatopentane contains an amount of emulsifier B) sufficient to ensure the dispersibility of the polyisocyanate mixture.

[0053] The preparation of the hydrophilically modified polyisocyanate composition based on 1,5-diisocyanatopentane, comprising polyisocyanurate polyisocyanate A) and at least one nonionic emulsifier B), can preferably be carried out solvent-free or optionally in a suitable solvent inert towards isocyanate groups. Suitable solvents include, for example, the commonly known paint solvents, such as...Ethyl acetate, butyl acetate, ethylene glycol monomethyl or ethyl ether acetate, 1-methoxypropyl-2-acetate, 3-methoxy-n-butyl acetate, acetone, 2-butanone, 4-methyl-2-pentanone, cyclohexanone, toluene, xylene, chlorobenzene, white spirit, highly substituted aromatics such as those marketed under the names solvent naphtha, Solvesso®, Isopar®, Nappar® (Deutsche EXXON CHEMICAL GmbH, Cologne, DE) and Shellsol® (Deutsche Shell Chemie GmbH, Eschborn, DE), carbonic acid esters such as dimethyl carbonate, diethyl carbonate, 1,2-ethylene carbonate and 1,2-propylene carbonate, lactones such as β-propiolactone, γ-butyrolactone, s-caprolactone and s-mcthylcaprolactone. but also solvents such as propylene glycol diacetate, diethylene glycol dimethyl ether, dipropylene glycol dimethyl ether, diethylene glycol ethyl and butyl ether acetate, N-methylpyrrolidone and N-methylcaprolactam, or any mixtures of such solvents.

[0054] The hydrophilically modified polyisocyanate compositions based on 1,5-diisocyanatopentane are clear, light-colored polyisocyanate mixtures that are easily dispersed in water by simply stirring, without the need for high shear forces. They are characterized by comparatively low viscosities, which are reduced by at least 20%, preferably at least 30%, and particularly preferably at least 40% compared to pure polyisocyanurate polyisocyanate A), and / or typically range from 3600 to 9600 mPas, preferably from 4200 to 8800 mPas, and particularly preferably from 4800 to 8000 mPas at 23°C, as determined according to DIN EN ISO 3219:1994-10 at a shear rate of 250 s'. 1 .

[0055] The excellent dispersibility, even at low emulsifier contents, in compounds with low viscosity and high NCO functionalities is particularly advantageous for the use of the hydrophilically modified polyisocyanate composition in aqueous 2K PUR coatings. This allows for the creation of highly dispersed coatings that, in addition to very good solvent and chemical resistance, exhibit excellent water resistance due to the low content of hydrophilic groups. If desired, any further non-hydrophilic polyisocyanates, especially PDI polyisocyanates of the type mentioned above, can be added to the hydrophilically modified polyisocyanate composition based on 1,5-diisocyanatopentane before emulsification. In such mixtures, the hydrophilically modified polyisocyanates act as an emulsifier for the subsequently added portion of non-hydrophilic polyisocyanates.

[0056] The polyisocyanate compositions represent valuable starting materials for the production of polyurethane plastics, especially according to the isocyanate polyaddition process, and are used for this purpose.

[0057] The invention relates to coating materials comprising at least one of the previously described polyisocyanate compositions and at least one binder component, which preferably comprises a compound reactive towards isocyanate groups, and optionally further auxiliary and additive materials.

[0058] The polyisocyanate composition is preferably used as a crosslinker for water-soluble or dispersed paint binders or paint binder components with groups reactive towards isocyanate groups, in particular alcoholic hydroxyl groups, in the production of coatings using aqueous coating materials based on such binders or binder components. The crosslinker, optionally in emulsified form, can be combined with the binders or binder components by simple stirring before processing the coating materials using any method or by using two-component spray guns.

[0059] In this context, examples of suitable binders or binder components include: water-soluble or dispersed polyacrylates containing hydroxyl groups, particularly those with a molecular weight in the range of 1,000 to 10,000 g / mol, which, when combined with organic polyisocyanates as crosslinkers, form valuable two-component binders; or water-dispersed, optionally urethane-modified, hydroxyl-group-containing polyester resins of the type known from polyester and alkyd resin chemistry. In principle, all water-soluble or dispersed binders that have reactive groups towards isocyanates are suitable as reaction partners for the polyisocyanate compositions according to the invention. This includes, for example, water-dispersed polyurethanes or polyamides, which can be crosslinked with polyisocyanates due to the active hydrogen atoms present in the urethane or amide groups.

[0060] In the coating composition according to the invention, the polyisocyanate composition is generally used as a binder component for aqueous paint binders in such quantities that correspond to an equivalent ratio of NCO groups to groups reactive towards NCO groups, in particular alcoholic hydroxyl groups, of 0.5:1 to 2:1.

[0061] If necessary, the polyisocyanate composition can also be added in subordinate quantities to non-functional aqueous paint binders to achieve very specific properties, for example as an additive to improve adhesion.

[0062] Naturally, the polyisocyanate composition can also be used in combination with the aforementioned aqueous coating binders or coating binder components in aqueous one-component polyurethane curing systems, in a form blocked by blocking agents known from polyurethane chemistry. Suitable blocking agents include, for example, diethyl malonate, acetoacetic ester, acetone oxime, butanone oxime, N,N-diisopropylamine, α-caprolactam, 3,5-dimethylpyrazole, 1,2,4-triazole, dimethyl 1,2,4-triazole, imidazole, or any mixtures of these blocking agents.

[0063] Any substrates can be used as substrates for the aqueous coatings formulated with the polyisocyanate composition, such as metal, wood, glass, stone, ceramic materials, concrete, hard and flexible plastics, textiles, leather and paper, which may also be primed with conventional primers before coating.

[0064] In general, aqueous coatings formulated with the polyisocyanate composition, to which the auxiliary and additive agents commonly used in the paint sector, such as leveling agents, color pigments, fillers, matting agents or emulsifiers, may be incorporated, already possess good coating properties when dried at room temperature.

[0065] Of course, they can also be dried under forced conditions at elevated temperatures or by baking at temperatures up to 260 °C.

[0066] Due to its excellent water emulsifiability, which enables a homogeneous, particularly fine distribution in aqueous coating binders, the use of the polyisocyanate composition as a binder component for aqueous polyurethane coatings leads to coatings with excellent optical properties, especially high surface gloss, flow and high transparency.

[0067] Besides its preferred use as a crosslinking component for aqueous 2K PUR coatings, the hydrophilically modified polyisocyanate composition based on PDI is ideally suited as a crosslinker for aqueous dispersion adhesives, leather and textile coatings or textile printing pastes, as an AOX-free paper auxiliaries, or as an additive for mineral building materials, for example, concrete or mortar. The invention also relates to a coating that can be achieved by using the coating agents described above.

[0068] The invention also relates to the use of a polyisocyanate composition comprising

[0069] at least one polyisocyanurate polyisocyanate A) based on 1,5-diisocyanatopentane having a number-mean molecular weight of at least 680 g / mol and a weight ratio of isocyanurate trimer to isocyanurate pentamer of less than 2.2, and

[0070] an emulsifier component B), comprising a urethane obtainable by urethanization of a polyisocyanurate polyisocyanate A) with a hydrophilic polyether monoalcohol having a number-average molecular weight of 400 to 600 g / mol, wherein the number-average molecular weight can be determined by gel permeation chromatography as specified in the description, for the production of polyurethane plastics, in particular polyurethane coatings.

[0071] The polyisocyanate composition already described as a component of the coating material according to the invention is itself ideally suited for the production of polyurethane plastics. It is particularly suitable for the production of polyurethane coatings. Finally, the invention relates to the use of a polyisocyanate composition.

[0072] at least one polyisocyanurate polyisocyanate A) based on 1,5-diisocyanatopentane having a number-mean molecular weight of at least 680 g / mol and a weight ratio of isocyanurate trimer to isocyanurate pentamer of less than 2.2, and

[0073] an emulsifier component B), comprising a urethane obtainable by urethanizing a polyisocyanurate polyisocyanate A) with a hydrophilic polyether monoalcohol having a number-average molecular weight of 400 to 600 g / mol, wherein the number-average molecular weight can be determined by gel permeation chromatography as described, for the production of a polyisocyanate mixture P) with reduced viscosity compared to a polyisocyanate mixture Q), wherein the polyisocyanate mixture Q) differs from the polyisocyanate mixture P) only in that the polyisocyanate mixture Q) does not include an emulsifier component B), and wherein the viscosity can be determined according to DIN EN ISO 3219:1994-10 at a shear rate of 250 s⁻¹. 1 .

[0074] The same polyisocyanate composition is also suitable for producing a polyisocyanate mixture P), as it reduces its viscosity. This means that a polyisocyanate mixture P), comprising the described polyisocyanurate polyisocyanate A) and the described emulsifier component B), has a lower viscosity than another polyisocyanate mixture Q), which is identical to the polyisocyanate mixture P) – except for the presence of the emulsifier component B).

[0075] The preferred embodiments of the polyisocyanate mixtures described above are also preferred for both of the aforementioned uses.

[0076] In particular, it is therefore independently preferred in the uses if the polyisocyanurate polyisocyanate A) has a number-average molecular weight of at least 700 g / mol, preferably at least 720 g / mol, or a weight ratio of isocyanurate trimer to isocyanurate pentamer of less than 2.0, preferably less than 1.9, or both.

[0077] It is further preferred for the uses independently of each other if the polyisocyanurate polyisocyanate A) has a mean NCO functionality of 3.3 to 5.0, an isocyanate group content of 15.0 to 22.9 wt.%, determinable according to DIN EN ISO 11909:2007-05, or a viscosity at 23 °C of 6000 to 12000 mPas, determinable according to DIN EN ISO 3219: 1994-10 at a shear rate of 250 s 1 exhibits, or any combination of two or three of the aforementioned characteristics.

[0078] It is also preferred for both uses independently if the polyisocyanurate polyisocyanate A) was produced using exclusively 1,5-diisocyanatopentane as the diisocyanate, has a mean NCO functionality of 3.4 to 5.0, preferably 3.5 to 4.5, an isocyanate group content of 17.0 to 22.9 wt.%, preferably 19.0 to 22.5 wt.%, determinable according to DIN EN ISO 11909:2007-05, or a viscosity at 23 °C of 7000 to 11000 mPas, preferably 8000 to 10000 mPas, determinable according to DIN EN ISO 3219:1994-10 at a shear rate of 250 s 1 , or any combination of two or three of the aforementioned features. It is also preferred for both uses independently if the hydrophilic polyether monoalcohol is obtainable by alkoxylation of a monohydric alcohol having a molecular weight of 32 to 74 g / mol, or has, on average, 8.5 to 13 ethylene oxide units per molecule, or both.

[0079] It is also preferred for both uses independently if the alkylene oxide units of the hydrophilic polyether monoalcohol consist of ethylene oxide units to 100 mol% or at least 80 mol%, preferably at least 90 mol%, in each case based on the total amount of alkylene oxide units.

[0080] It is also preferred for both uses independently if the hydrophilic polyether monoalcohol comprises or consists of pure polyethylene glycol monomethyl ether alcohols, in particular if these have on average 8.5 to 13, preferably 9 to 12 and particularly preferably 10 to 11 ethylene oxide units. It is also preferred for both uses independently if the emulsifier component B) is prepared by reacting at least one polyisocyanurate polyisocyanate A) with at least one hydrophilic polyether monoalcohol while maintaining an NCO / OH equivalent ratio of 2:1 to 400:1, preferably 4:1 to 140:1.

[0081] It is still preferred for both uses if the hydrophilic polyether monoalcohol is not bound to the polyisocyanurate polyisocyanate A) via allophant groups.

[0082] Finally, for both uses independently, it is preferred if the polyisocyanate composition has a viscosity at 23 °C of 3600 to 9600 mPas, preferably of 4200 to 8800 mPas, particularly preferably of 4800 to 8000 mPas, each determinable according to DIN EN ISO 3219: 1994-10 at a shear rate of 250 s 1 , exhibits. Examples

[0083] Unless otherwise stated, all percentages refer to weight.

[0084] The NCO content was determined titrimetrically according to DIN EN ISO 11909:2007-05.

[0085] All viscosity measurements were performed using a Physica MCR 51 rheometer from Anton Paar Germany GmbH (DE) according to DIN EN ISO 3219:1994-10 at a shear rate of 250 s⁻¹. 1 .

[0086] The residual monomer content was measured by gas chromatography with an internal standard according to DIN EN ISO 10283:2007-11.

[0087] Unless otherwise stated, the number-mean molecular weight (Mn) of a polyisocyanate was determined using software-assisted gel permeation chromatography (GPC) at 23 °C in tetrahydrofuran as solvent. The measurement was performed according to DIN 55672-1:2016-03 "Gel permeation chromatography, Part 1 - Tetrahydrofuran as eluent" (SECurity GPC system from PSS Polymer Service, flow rate 1.0 ml / min; columns: 2*PSS SDV linear M, 8x300 mm, 5 pm; RID detector). Samples of polystyrene standards with known molecular weights were used for calibration.

[0088] The weight ratio of isocyanurate trimer (n = 3) to isocyanurate pentamer (n = 5) is derived from the ratios of the respective area percentages taken from the chromatograms of the aforementioned GPC method, which were approximately equated to weight fractions.

[0089] To assess dispersibility, the mean particle sizes in aqueous dispersions were determined using a Zetasizer, type DTS 5100, from Malvern Instruments GmbH (DE). For this purpose, 25 g of a polyisocyanate composition were mixed with 100 g of deionized water in an Erlenmeyer flask and then stirred for 1 minute at 900 rpm using a magnetic stirrer. The mean particle size of the resulting aqueous dispersions was then determined.

[0090] Output connections

[0091] Polyisocyanurate polyisocyanate Al)

[0092] 1000 g (6.49 mol) of 1,5-pentamethylene diisocyanate (PDI) were placed in a four-necked flask equipped with a stirrer, reflux condenser, nitrogen feed tube, and internal thermometer. The flask was degassed three times at room temperature by applying a vacuum of approximately 50 mbar and purged with nitrogen. The mixture was then heated to 60 °C, and the catalyst solution (1.5% N,N,N-trimethyl-N-benzylammonium hydroxide solution in a 1:1 mixture of methanol and 2-ethyl-1-hexanol) was added at such a rate that the temperature of the reaction mixture rose to a maximum of 80 °C, despite the exothermic onset of the trimerization reaction. After reaching an NCO content of 36.6 wt%, the reaction was stopped with dibutyl phosphate (equimolar amount based on the trimethylbenzylammonium hydroxide used) and the unreacted monomeric PDI was separated in a thin-film evaporator at a temperature of 140 °C and a pressure of 0.5 mbar.A practically colorless polyisocyanurate polyisocyanate was obtained, exhibiting the following characteristics:

[0093] NCO content: 21.6%

[0094] NCO functionality (calculated): approx. 3.8

[0095] Viscosity (23 °C): 9800 mPas

[0096] monomeric PDF 0.04%

[0097] Mn: 788 g / mol

[0098] Isocyanurate trimer (n = 3) : Isocyanurate pentamer (n = 5) = 40.7 wt% : 22.5 wt% = 1.81

[0099] Polytherm nonalcohols

[0100] MPEG 350: Methoxypolyethylene glycol, average molecular weight of 350 g / mol

[0101] MPEG 500: Methoxypolyethylene glycol, average molecular weight of 500 g / mol

[0102] MPEG 750: Methoxypolyethylene glycol, average molecular weight of 750 g / mol

[0103] Example 1)

[0104] (according to the invention)

[0105] 850 g (4.37 val) of polyisocyanurate polyisocyanate (Al) were heated at 100 °C under dry nitrogen with stirring. Within 30 minutes, a mixture of 66 g (0.19 val) of MPEG 350 and 84 g (0.17 val) of MPEG 500, corresponding to a polyether monoalcohol with an average molecular weight of approximately 420 g / mol, was added. Stirring continued at this temperature until the NCO content of the mixture had decreased to 16.8% after about 2 hours. After cooling to room temperature, a colorless, clear polyisocyanate mixture with the following properties was obtained:

[0106] NCO content: 16.8%

[0107] NCO functionality: 3.5

[0108] Viscosity (23 °C): 7030 mPas

[0109] Average particle size: 89 nm (Example 2)

[0110] (according to the invention)

[0111] 850 g (4.37 val) of polyisocyanurate polyisocyanate (Al) were heated at 100 °C under dry nitrogen with stirring. Within 30 minutes, a mixture of 150 g (0.30 val) of MPEG 500 was added and stirred at this temperature until the NCO content of the mixture had decreased to 17.1% after approximately 2 hours. After cooling to room temperature, a colorless, clear polyisocyanate mixture was obtained with the following properties:

[0112] NCO content: 17.1%

[0113] NCO functionality: 3.5

[0114] Viscosity (23 °C): 6200 mPas

[0115] Average particle size: 90 nm

[0116] Example 3)

[0117] (according to the invention)

[0118] 850 g (4.37 val) of polyisocyanurate polyisocyanate (Al) were heated at 100 °C under dry nitrogen with stirring. Within 30 minutes, a mixture of 75 g (0.15 val) of MPEG 500 and 75 g (0.10 val) of MPEG 750, corresponding to a polyether monoalcohol with an average molecular weight of approximately 600 g / mol, was added. Stirring continued at this temperature until the NCO content of the mixture had decreased to 17.3% after about 2 hours. After cooling to room temperature, a colorless, clear polyisocyanate mixture with the following properties was obtained:

[0119] NCO content: 17.3%

[0120] NCO functionality: 3.5

[0121] Viscosity (23 °C): 7360 mPas

[0122] Average particle size: 93 nm

[0123] Example 4)

[0124] (Comparison based on Example 1 of WO 2016 / 146579)

[0125] 850 g (4.37 val) of polyisocyanurate polyisocyanate (Al) were heated at 100 °C under dry nitrogen with stirring. Within 30 minutes, 150 g (0.06 val) of MPEG 350 were added, and the mixture was stirred at this temperature until the NCO content of the mixture had decreased to 16.6% after approximately 2 hours. After cooling to room temperature, a colorless, clear polyisocyanate mixture was obtained with the following properties:

[0126] NCO content: 16.6% NCO functionality: 3.4

[0127] Viscosity (23 °C): 8100 mPas

[0128] Average particle size: 83 nm

[0129] Example 5)

[0130] (Comparison)

[0131] 850 g (4.37 val) of polyisocyanurate polyisocyanate (Al) were heated at 100 °C under dry nitrogen with stirring. Within 30 minutes, a mixture of 32 g (0.06 val) of MPEG 500 and 118 g (0.16 val) of MPEG 750, corresponding to a polyether monoalcohol with an average molecular weight of approximately 680 g / mol, was added. Stirring continued at this temperature until the NCO content of the mixture had decreased to 17.4% after about 2 hours. After cooling to room temperature, a colorless, clear polyisocyanate mixture with the following properties was obtained:

[0132] NCO content: 17.4%

[0133] NCO functionality: 3.6

[0134] Viscosity (23 °C): 8320 mPas

[0135] Average particle size: 92 nm

[0136] The examples show that urethanization with methoxypolyethylene glycols in the molecular weight range of 420 to 600 g / mol (Examples 1 to 3) leads to hydrophilically modified products that exhibit significantly lower viscosities compared to the starting polyisocyanurate polyisocyanate, while urethanization with methoxypolyethylene glycols with average molecular weights outside the specified range (Comparative Examples 4 and 5) only slightly reduces the viscosity. The average molecular weight of the respective polyether monoalcohol used has no influence on the dispersibility, as can be seen from the similar average particle sizes.

Claims

Patent claims 1. Coating material comprising a comprising a polyisocyanate composition at least one polyisocyanurate polyisocyanate A) based on 1,5-diisocyanatopentane having a number-mean molecular weight of at least 680 g / mol and a weight ratio of isocyanurate trimer to isocyanurate pentamer of less than 2.2, and an emulsifier component B), comprising a urethane obtainable by urethanization of a polyisocyanurate polyisocyanate A) with a hydrophilic polyether monoalcohol having a number-average molecular weight of 400 to 600 g / mol, wherein at least 60 wt%, based on the total amount of the hydrophilic polyether monoalcohol, of the hydrophilic polyether monoalcohol is not bound to the polyisocyanurate polyisocyanate A) via allophanate groups, and wherein the number-average molecular weight can be determined by gel permeation chromatography as described above, and at least one binder component, which preferably comprises at least one compound reactive towards isocyanate groups, as well as possibly other auxiliary and additive substances.

2. Coating composition according to claim 1, characterized in that the polyisocyanurate polyisocyanate A) has a number-average molecular weight of at least 700 g / mol, preferably at least 720 g / mol, and a weight ratio of isocyanurate trimer to isocyanurate pentamer of less than 2.0, preferably less than 1.

9.

3. Coating composition according to one of claims 1 and 2, characterized in that the polyisocyanurate polyisocyanate A) has a mean NCO functionality of 3.3 to 5.0, an isocyanate group content of 15.0 to 22.9 wt.%, determinable according to DIN EN ISO 11909:2007-05, and a viscosity at 23 °C of 6000 to 12000 mPas, determinable according to DIN EN ISO 3219:1994-10 at a shear rate of 250 s 1 , exhibits.

4. Coating composition according to any one of claims 1 to 3, characterized in that the polyisocyanurate polyisocyanate (A) is produced using exclusively 1,5-diisocyanatopentane as the diisocyanate, has an average NCO functionality of 3.4 to 5.0, preferably 3.5 to 4.5, an isocyanate group content of 17.0 to 22.9 wt.%, preferably 19.0 to 22.5 wt.%, determinable according to DIN EN ISO 11909:2007-05, and a viscosity at 23 °C of 7000 to 11000 mPas, preferably 8000 to 10000 mPas, determinable according to DIN EN ISO 3219:1994-10 at a shear rate of 250 s 1 , exhibits.

5. Coating composition according to any one of claims 1 to 4, characterized in that the hydrophilic polyether monoalcohol is obtainable by alkoxylation of a monohydric alcohol having a molecular weight of 32 to 74 g / mol and having, on average, 8.5 to 13 ethylene oxide units per molecule.

6. Coating composition according to any one of claims 1 to 5, characterized in that the alkylene oxide units of the hydrophilic polyether monoalcohol consist of ethylene oxide units to 100 mol% or to at least 80 mol%, preferably to at least 90 mol%, in each case based on the total amount of alkylene oxide units.

7. Coating composition according to any one of claims 1 to 6, characterized in that the hydrophilic polyether monoalcohol comprises or consists of pure polyethylene glycol monomethyl ether alcohols, which on average have 8.5 to 13, preferably 9 to 12 and particularly preferably 10 to 11 ethylene oxide units.

8. Coating composition according to any one of claims 1 to 7, characterized in that the emulsifier component B) is produced by reacting at least one polyisocyanurate polyisocyanate A) with at least one hydrophilic polyether monoalcohol while maintaining an NCO / OH equivalent ratio of 2:1 to 400:1, preferably from 4:1 to 140:

1.

9. Coating composition according to any one of claims 1 to 8, wherein the polyisocyanate composition has a viscosity at 23 °C of 3600 to 9600 mPas, preferably of 4200 to 8800 mPas, particularly preferably of 4800 to 8000 mPas, in each case determined according to DIN EN ISO 3219: 1994-10 at a shear rate of 250 s 1 , exhibits.

10. Method for producing the coating agent according to one of claims 1 to 9, characterized in that the polyisocyanurate polyisocyanate A) is mixed with the emulsifier component B) to obtain the polyisocyanate composition, or the polyisocyanate composition is obtained by partial reaction of polyisocyanates of the polyisocyanurate polyisocyanate A) with the hydrophilic polyether monoalcohol, and the obtained polyisocyanate composition is mixed with the binder component and optionally with auxiliary and additive substances.

11. Method according to claim 10, characterized in that the polyisocyanate composition is obtained by partial reaction of polyisocyanates of the polyisocyanurate polyisocyanate A) with the hydrophilic polyether monoalcohol and the partial reaction takes place at temperatures of 40 to 180 °C, preferably 50 to 150 °C.

12. Coating obtainable by using the coating material according to any one of claims 1 to 9 or the coating material obtained by the method according to any one of claims 10 and 11.

13. Use of a polyisocyanate composition comprising at least one polyisocyanurate polyisocyanate A) based on 1,5-diisocyanatopentane having a number-mean molecular weight of at least 680 g / mol and a weight ratio of isocyanurate trimer to isocyanurate pentamer of less than 2.2, and an emulsifier component B), comprising a urethane obtainable by urethanizing a polyisocyanurate polyisocyanate A) with a hydrophilic polyether monoalcohol having a number-average molecular weight of 400 to 600 g / mol, wherein the number-average molecular weight can be determined by gel permeation chromatography as described, for the production of polyurethane plastics, in particular polyurethane coatings, or for the production of a polyisocyanate mixture P) with reduced viscosity compared to a polyisocyanate mixture Q), wherein the polyisocyanate mixture Q) differs from the polyisocyanate mixture P) only in that the polyisocyanate mixture Q) does not comprise an emulsifier component B), and wherein the viscosity can be determined according to DIN EN ISO 3219:1994-10 at a shear rate of 250 s⁻¹. 1 .

14. Use according to claim 13, characterized in that the polyisocyanurate polyisocyanate A) has a number-average molecular weight of at least 700 g / mol, preferably at least 720 g / mol, and a weight ratio of isocyanurate trimer to isocyanurate pentamer of less than 2.0, preferably less than 1.9, and / or that the polyisocyanurate polyisocyanate A) has a mean NCO functionality of 3.3 to 5.0, an isocyanate group content of 15.0 to 22.9 wt.%, determinable according to DIN EN ISO 11909:2007-05, and a viscosity at 23 °C of 6000 to 12000 mPas, determinable according to DIN EN ISO 3219:1994-10 at a shear rate of 250 s 1 , exhibits, and / or that the polyisocyanurate polyisocyanate A) was produced using exclusively 1,5-diisocyanatopentane as the diisocyanate, has a mean NCO functionality of 3.4 to 5.0, preferably 3.5 to 4.5, an isocyanate group content of 17.0 to 22.9 wt.%, preferably 19.0 to 22.5 wt.%, determinable according to DIN EN ISO 11909:2007-05, and a viscosity at 23 °C of 7000 to 11000 mPas, preferably 8000 to 10000 mPas, determinable according to DIN EN ISO 3219:1994-10 at a shear rate of 250 s 1 , exhibits.

15. Use according to one of claims 13 and 14, characterized in that the hydrophilic polyether monoalcohol is obtainable by alkoxylation of a monohydric alcohol having a molecular weight of 32 to 74 g / mol and having, on average, 8.5 to 13 ethylene oxide units per molecule, and / or that the alkylene oxide units of the hydrophilic polyether monoalcohol consist of ethylene oxide units to 100 mol% or at least 80 mol%, preferably at least 90 mol%, in each case based on the total amount of alkylene oxide units, and / or that the hydrophilic polyether monoalcohol comprises or consists of pure polyethylene glycol monomethyl ether alcohols, which on average have 8.5 to 13, preferably 9 to 12 and particularly preferably 10 to 11 ethylene oxide units, 16. Use according to any one of claims 13 to 15, characterized in that the emulsifier component B) is produced by reacting at least one polyisocyanurate polyisocyanate A) with at least one hydrophilic polyether monoalcohol while maintaining an NCO / OH equivalent ratio of 2:1 to 400:1, preferably from 4:1 to 140:1, and / or that the polyisocyanate composition has a viscosity at 23 °C of 3600 to 9600 mPas, preferably of 4200 to 8800 mPas, particularly preferably of 4800 to 8000 mPas, each determinable according to DIN EN ISO 3219: 1994-10 at a shear rate of 250 s 1 , exhibits.