Polyisocyanates containing allophanate and silane groups

0001The invention relates to polyisocyanates containing allophanate and silane groups, a process for their preparation and their use as a starting component in the production of polyurethane plastics, in particular as a crosslinking component in polyurethane lacquers and coatings.

0002Polyisocyanate mixtures containing alkoxysilane groups have been known for a long time. Products of this type which, in addition to the isocyanate group, contain a second reactive structure, ie a structure capable of crosslinking, have been used in the past in various polyurethane systems and applications to achieve special properties, for example to improve the adhesion, chemical or scratch resistance of coatings.

0003For example, the <patcit id="pcit0001" dnum="WO03054049A"><text>WO 03/054049</text></patcit> Isocyanate-functional silanes, produced from low-monomer aliphatic or cycloaliphatic polyisocyanates and secondary aminopropyltrimethoxysilanes, as adhesion promoters for polyurethane hotmelt adhesives.

0004Even after the teaching of <patcit id="pcit0002" dnum="JP2005015644A"><text>JP-A 2005015644</text></patcit> the adhesion of adhesives and sealants can be improved by using polyisocyanates or isocyanate prepolymers modified with N-substituted, ie secondary aminopropylalkoxysilanes.

0005The <patcit id="pcit0003" dnum="EP0994139B"><text>EP-B 0 994 139</text></patcit> claims reaction products of aliphatic or cycloaliphatic polyisocyanates with inferior amounts of alkoxysilane-functional aspartic esters, as described in the <patcit id="pcit0004" dnum="EP0596360A"><text>EP 0 596 360</text></patcit> are described as reactants for isocyanate-functional compounds, and optionally polyethylene oxide polyether alcohols as binders for one-component moisture-crosslinking coatings, adhesives or sealants with accelerated curing.

0006Reaction products of aliphatic or cycloaliphatic polyisocyanates with inferior amounts of alkoxysilane-functional aspartic esters or secondary aminoalkylsilanes are also in the <patcit id="pcit0005" dnum="WO02058569A"><text>WO 02/058569</text></patcit> described as crosslinking components for two-component polyurethane adhesive primers.

0007The <patcit id="pcit0006" dnum="EP0872499B"><text>EP-B 0 872 499</text></patcit> describes aqueous two-component polyurethane coatings which contain compounds containing isocyanate and alkoxysilyl groups as the crosslinking component. The use of these special polyisocyanates leads to coatings with improved water resistance and high gloss at the same time.

0008Hydrophilically modified and therefore more easily emulsifiable polyisocyanates containing alkoxysilane groups have also already been mentioned as crosslinking components for aqueous two-component lacquer and adhesive dispersions (e.g. <patcit id="pcit0007" dnum="EP0949284A"><text>EP-A 0 949 284</text></patcit>).

0009Reaction products of aliphatic and / or cycloaliphatic polyisocyanates with N, N-bis (trialkoxysilylpropyl) amines as crosslinking agent components have recently been proposed to improve the scratch resistance of solvent-borne thermosetting 2-component PU automotive clearcoats or topcoats (<patcit id="pcit0008" dnum="EP1273640A"><text>EP 1 273 640</text></patcit>).

0010All these polyisocyanate mixtures containing silane groups have in common that they are prepared by the partial reaction of unmodified polyisocyanates or polyisocyanate prepolymers with organofunctional silanes containing groups that are reactive toward isocyanate groups, for example mercapto-functional silanes, primary aminoalkylsilanes, secondary N-alkyl-substituted aminoalkylsilanes or alkaragoxysilane functionalities.

0011However, such a modification inevitably leads to a lowering of the average isocyanate functionality based on that of the starting polyisocyanates used, which has a greater effect the higher the desired silane content in the reaction product. In practice, in the above applications, such as. B. lacquers or adhesives, desired to achieve a high network density but especially polyisocyanate crosslinking agents with the highest possible isocyanate functionality.

0012In addition, with increasing degree of modification, the viscosity of the products increases drastically due to the thiourethane and in particular urea groups introduced into the molecule, which is why the previously known polyisocyanates containing silane groups can generally only be used in dissolved form using substantial amounts of organic solvents.

0013A further disadvantage of the previously known production processes for such products is that the reaction of polyisocyanates with organofunctional silanes which are reactive toward isocyanates leads to a statistical distribution of the silane functions over the oligomeric polyisocyanate mixture. In addition to the desired silane-functionalized polyisocyanates, the reaction mixture always contains unmodified starting polyisocyanate as well as - increasingly with increasing degree of modification - completely isocyanate-free, exclusively carrying silane groups as reactive groups. When using such products as crosslinkers in polyurethane systems, this leads to an inhomogeneous distribution of the silane units in the polymer structure and thus not to the best possible level of properties.

0014The object of the present invention was therefore to provide new polyisocyanates containing silane groups which do not have the disadvantages of the prior art. These new polyisocyanates should have both functionalities, ie isocyanate and silane groups, in each molecule, and at the same time have high average isocyanate functionalities and nevertheless low viscosities.

0015This object was achieved by providing the polyisocyanates modified according to the invention described in more detail below and the process for their preparation.

0016The present invention is based on the surprising observation that hydroxy urethanes containing silane groups or Hydroxyamides, which are accessible by reacting aminoalkylsilanes with cyclic carbonates or lactones with ring opening, can easily be converted with excess amounts of monomeric diisocyanates to storage-stable, bright-colored allophanate polyisocyanates, which are characterized by low viscosities even with high isocyanate functionalities and high silane contents.

0017The present invention relates to a process for the preparation of polyisocyanates containing allophanate groups by reaction<ul id="ul0001" list-style="none"><li>A) at least one - from the reaction of aminosilanes with cyclic carbonates or lactones - containing silane groups containing hydroxy urethane and / or hydroxyamides with a molar excess amount based on the NCO-reactive groups of component A)</li><li>B) at least one diisocyanate with aliphatic, cycloaliphatic, araliphatic and / or aromatically bound isocyanate groups and optionally subsequent removal of the unreacted excess diisocyanate.</li></ul>

0018The invention also relates to the allophanate and silane groups-containing polyisocyanates obtainable by this process, and to their use as starting components in the production of polyurethane plastics, in particular as a crosslinking component in polyurethane lacquers and coatings.

0019Starting compounds A) for the process according to the invention are any reaction products of aminosilanes with cyclic carbonates or lactones.

0020Suitable aminosilanes for the preparation of the starting compounds A) are, for example, those of the general formula (I)<chemistry id="chem0001" num="0001"><img file="EP2014692A2_D0001.tif" /></chemistry>in which<dl id="dl0001" compact="compact"><dt>R¹, R² and R³</dt><dd>stand for identical or different radicals and each represent a saturated or unsaturated, linear or branched, aliphatic or cycloaliphatic or an optionally substituted aromatic or araliphatic radical with up to 18 carbon atoms, which optionally contain up to 3 heteroatoms from the series oxygen, sulfur, nitrogen can,</dd><dt>X</dt><dd>represents a linear or branched organic radical with at least 2 carbon atoms, which may optionally contain up to 2 imino groups (-NH-), and</dd><dt>R⁴</dt><dd>for hydrogen, a saturated or unsaturated, linear or branched, aliphatic or cycloaliphatic or an optionally substituted aromatic or araliphatic radical with up to 18 carbon atoms or a radical of the formula<chemistry id="chem0002" num="0002"><img file="EP2014692A2_D0002.tif" /></chemistry>is in which R¹, R², R³ and X have the meaning given above.</dd></dl>

0021Suitable aminosilanes are, for example, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-aminopropylethyldiethoxysilane, 3-aminopropyldimethylethoxysilane, 3-aminopropyldiisopropylethoxysilane, 3-aminopropyltripropoxysilane, 3-Aminopropyltributoxysilan, 3-aminopropylphenyldiethoxysilane, 3-Aminopropylphenyldimethoxysilan, 3- Aminopropyl-tris (methoxyethoxyethoxy) silane, 2-aminoisopropyltrimethoxysilane, 4-aminobutyltrimethoxysilane, 4-aminobutyltriethoxysilane, 4-aminobutylmethyldimethoxysilane, 4-aminobutylmethyldiethoxysilane, 4-Aminobutylethyldimethoxysilan, 4-aminobutylethyldiethoxysilane, 4-aminobutyldimethylmethoxysilane, 4-Aminobutylphenyldimethoxysilan, 4-aminobutylphenyldiethoxysilane, 4-amino (3-methylbutyl) methyldimethoxysilane, 4-amino ( 3-methylbutyl) methyldiethoxysilane, 4-amino (3-methylbutyl) trimethoxysilane, 3-aminopropylphenylmethyl-n-propoxysilane, 3-aminopropylmethyldibutoxysilane, 3-aminopropyldiethylmethylsilane, 3-aminopropylmethylbis (trimethylsiloxy) silane, 11-aminoundecyltrimethoxysilane, N-methyl-3-aminopropyltriethoxysilane, N- (n-butyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethylanimine) n-amoxysilane-3-amoxysilane (2-aminoethyl) -3-aminoisobutylmethyldimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, N- (2-aminoethyl) -3-aminopropyltris (2-ethylhexoxy) silane, N- (6-aminohexyl) -3- aminopropyltrimethoxysilane, N-Benzyl-N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, bis (3-trimethoxysilylpropyl) amine, bis (3-triethoxysilylpropyl) amine, (aminoethylaminomethyl) phenethyltrimethoxysilane, N-vinylbenzyl-N- (2-aminoethyl ) -3-aminopropylpolysiloxane, N-vinylbenzyl-N (2-aminoethyl) -3-aminopropylpolysiloxane, 3-ureidopropyltriethoxysilane, 3- (m-aminophenoxy) propyltrimethoxysilane, m- and / or p-aminophenyltrimetoxysilane Aminopropoxy) -3,3-dimethyl-1-propenyltrimethoxysilane, 3-aminopropylmethylbis (trimethylsiloxy) silane, 3-aminopropyltris (trimethylsiloxy) silane, 3-aminopropylpentamethyldisiloxane or any mixture of such aminosilanes.

0022Preferred aminosilanes for the preparation of the starting component A) are those of the general formula (I), in which<dl id="dl0002"><dt>R¹, R² and R³</dt><dd>stand for identical or different radicals and each represent a saturated, linear or branched, aliphatic or cycloaliphatic radical with up to 6 carbon atoms, which can optionally contain up to 3 oxygen atoms,</dd><dt>X</dt><dd>represents a linear or branched alkylene radical having 2 to 10 carbon atoms, which may optionally contain up to 2 imino groups (-NH-), and</dd><dt>R⁴</dt><dd>for hydrogen, a saturated, linear or branched, aliphatic or cycloaliphatic radical having up to 6 carbon atoms or a radical of the formula<chemistry id="chem0003" num="0003"><img file="EP2014692A2_D0003.tif" /></chemistry>is in which R¹, R², R³ and X have the meaning given above.</dd></dl>

0023Preferably stand<dl id="dl0003"><dt>R¹, R² and R³</dt><dd>each for alkyl radicals with up to 6 carbon atoms and / or alkoxy radicals which contain up to 3 oxygen atoms, with the proviso that at least one of the radicals R¹, R² and R³ represents such an alkoxy radical,</dd><dt>X</dt><dd>for a linear or branched alkylene radical with 3 or 4 carbon atoms, and</dd><dt>R⁴</dt><dd>represents hydrogen, a methyl radical or a radical of the formula<chemistry id="chem0004" num="0004"><img file="EP2014692A2_D0004.tif" /></chemistry>in which R¹, R², R³ and X have the meaning given above.</dd></dl>

0024Are particularly preferred<dl id="dl0004"><dt>R¹, R² and R³</dt><dd>each for methyl, methoxy and / or ethoxy, with the proviso that at least one of the radicals R¹, R² and R³ represents a methoxy or ethoxy radical,</dd><dt>X</dt><dd>for a propylene residue (-CH₂-CH₂-CH₂-), and</dd><dt>R⁴</dt><dd>represents hydrogen, a methyl radical or a radical of the formula<chemistry id="chem0005" num="0005"><img file="EP2014692A2_D0005.tif" /></chemistry>in which R¹, R², R³ and X have the meaning given above.</dd></dl>

0025Particularly preferred aminosilanes are 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldimethoxysilane and / or 3-aminopropylmethyldiethoxysilane.

0026In the preparation of the starting compounds A) for the process according to the invention, the aminosilanes mentioned are reacted with any cyclic carbonates and / or lactones with ring opening.

0027Suitable cyclic carbonates are in particular those with 3 or 4 carbon atoms in the ring, which may also be substituted, such as. B. 1,3-dioxolan-2-one (ethylene carbonate, EC), 4-chloro-1,3-dioxolan-2-one, 4,5-dichloro-1,3-dioxolan-2-one, 4-methyl-1 , 3-dioxolan-2-one (propylene carbonate, PC), 4-ethyl-1,3-dioxolan-2-one, 4,5-dimethyl-1,3-dioxolan-2-one, 4,4-dimethyl- 1,3-dioxolan-2-one, 4-hydroxymethyl-1,3-dioxolan-2-one (glycerol carbonate), 4-phenoxymethyl-1,3-dioxolan-2-one, 1,3-dioxan-2-one (Trimethylene carbonate), 5,5-dimethyl-1,3-dioxan-2-one, 5-methyl-5-propyl-1,3-dioxan-2-one, 5-ethyl-5- (hydroxymethyl) -1, 3-dioxan-2-one (TMP carbonate), 4-isopropyl-5,5-dimethyl-1,3-dioxan-2-one (2,2,4-trimethylpentan-1,3-diol carbonate), 4-tert-butyl-5-methyl-1,3 -dioxan-2-one (2,4,4-trimethylpentan-1,3-diol carbonate), 2,4-dioxaspiro [5.5] un-decan-3-one (cyclohexane-1,1-dimethanol spirocarbonate) or any Mixtures of such cyclic carbonates. Preferred cyclic carbonates are ethylene carbonate and / or propylene carbonate.

0028Suitable lactones are, for example, those with 3 to 6 carbon atoms in the ring, which can optionally also be substituted, such as. B. β-propiolactone, β-butyrolactone, β-butyrolactone, α-methyl-y-butyrolactone, γ-valerolactone, γ-phenyl-y-butyrolactone, α, α-diphenyl-γ-butyrolactone, γ-hexalactone (γ-caprolactone) , γ-heptalactone, γ-octalactone, γ-nonalactone, γ-decalactone, γ-undecalactone, γ-dodecalactone, γ-methyl-y-decanolactone, α-acetyl-y-butyrolactone, δ-valerolactone, δ-hexanolactone, δ Octanolactone, δ-nonanolactone, δ-decalactone, δ-undecalactone, δ-tridecalactone, δ-tetradecalactone, γ-ethyl-γ-butyl-δ-valerolactone, octahydrocoumarin, ε-capro-lactone, γ-phenyl-ε-caprolactone, ε-decalactone or any mixture of such lactones. Preferred lactones are β-propiolactone, γ-butyrolactone, γ-valerolactone, γ-caprolactone and / or ε-caprolactone.

0029The preparation of the starting compounds A) by reacting the aminosilanes mentioned with the cyclic carbonates or lactones is known per se and can be carried out, for example, according to the method described in <patcit id="pcit0009" dnum="SU295764"><text>SU 295764</text></patcit>, <patcit id="pcit0010" dnum="US4104296A"><text>US 4,104,296</text></patcit>, <patcit id="pcit0011" dnum="EP0833830B"><text>EP-B 0 833 830</text></patcit> or <patcit id="pcit0012" dnum="WO9818844A"><text>WO 98/18844</text></patcit> described procedures take place. In general, the reactants are reacted with one another at temperatures of 15 to 100 ° C., preferably 20 to 60 ° C., in equimolar amounts. However, it is also possible for one of the components, for example the aminosilane or the cyclic carbonate or lactone, to be used in a molar excess amount, but preferably in an excess of at most 10 mol%, particularly preferably of at most 5 mol% . The hydroxy-functional starting compounds A) obtainable in this way, which contain urethane groups when using cyclic carbonates and amide groups when lactones are used, are generally colorless, low-viscosity liquids.

0030Suitable starting compounds B) for the process according to the invention are any diisocyanates with aliphatic, cycloaliphatic, araliphatic and / or aromatically bound isocyanate groups which can be obtained by any process, eg. B. by phosgenation or by a phosgene-free route, for example by urethane cleavage. Suitable starting diisocyanates are, for example, those of the molecular weight range 140 to 400 g / mol, such as. B. 1,4-diisocyanatobutane, 1,6-diisocyanatohexane (HDI), 1,5-diisocyanato-2,2-dimethylpentane, 2,2,4- or 2,4,4-trimethyl-1,6-diisocyanatohexane, 1,10-diisocyanatodecane, 1,3- and 1,4-diisocyanatocyclohexane, 1,4-diisocyanato-3,3,5-trimethylcyclohexane, 1,3-diisocyanato -2-methylcyclohexane, 1,3-diisocyanato-4-methylcyclohexane, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (isophorone diisocyanate; IPDI), 1-isocyanato-1-methyl-4 (3) -isocyanatomethylcyclohexane, 2,4'- and 4,4'-diisocyanatodicyclohexylmethane, 1,3- and 1,4-bis (isocyanatomethyl) cyclohexane, 4,4 '-Diisocyanato-3,3'-dimethyldicyclohexylmethane, 4,4'-diisocyanato-3,3', 5,5'-tetra-methyldicyclohexylmethane, 4,4'-diisocyanato-1,1'-bi (cyclohexyl), 4 , 4'-diisocyanato-3,3'-dimethyl-1,1'-bi (cyclohexyl), 4,4'-diisocyanato-2,2 ', 5,5'-tetra-methyl-1,1'-bi (cyclohexyl), 1,8-diisocyanato-menthan, 1,3-diisocyanato-adamantane, 1,3-dimethyl-5,7-diisocyanatoadamantane, 1,3- and 1,4-bis (isocyanatomethyl) benzene, 1,3- and 1,4-bis (1-isocyanato-1-methylethyl) benzene ( TMXDI), bis (4- (1-isocyanato-1-methylethyl) phenyl) carbon ate, 1,3- and 1,4-phenylene diisocyanates, 2,4- and 2,6-tolylene diisocyanates as well as any mixtures of these isomers, diphenylmethane 2,4'- and / or -4,4'-diisocyanates and naphthylene-1,5-diisocyanate and any mixtures of such diisocyanates. Further diisocyanates which are also suitable can also be found, for example, in <nplcit id="ncit0001" npl-type="s"><text>Justus Liebigs Annalen der Chemie Volume 562 (1949) pp. 75-136</text></nplcit>.

0031Preferred starting component B) are the diisocyanates mentioned with aliphatic and / or cycloaliphatic isocyanate groups.

0032Particularly preferred starting components B) for the process according to the invention are 1,6-diisocyanatohexane, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane, 2,4'- and / or 4,4'-diisocyanatodicyclohexylmethane or any mixtures thereof diisocyanates.

0033To carry out the process according to the invention, the silane groups-containing hydroxyurethanes and / or hydroxyamides A) with the diisocyanates B) at temperaturesfrom 40 to 200 ° C., preferably 60 to 180 ° C., while maintaining an equivalent ratio of isocyanate groups to groups reactive toward isocyanates from 4: 1 to 50: 1, preferably from 5: 1 to 30: 1, converted to allophanate polyisocyanates.

0034For the purposes of the present invention, the “isocyanate-reactive groups” in addition to the hydroxyl groups of component A) and the urethane groups formed therefrom by means of an NCO / OH reaction, if the hydroxyurethanes are used, also include the urethane groups already contained therein, since these are under the reaction conditions continue to react to allophanate groups.

0035The process according to the invention can be carried out uncatalyzed as thermally induced allophanatization. However, suitable catalysts are preferably used to accelerate the allophanatization reaction. These are the usual known allophanatization catalysts, for example metal carboxylates, metal chelates or tertiary amines<patcit id="pcit0013" dnum="GB0994890A"><text>GB-A-0 994 890</text></patcit> described to alkylating agents of the type described in the <patcit id="pcit0014" dnum="US3769318A"><text>US-A-3 769 318</text></patcit> described type or to strong acids, as in the <patcit id="pcit0015" dnum="EP0000194A"><text>EP-A-0 000 194</text></patcit> are described by way of example.

0036Suitable allophanatization catalysts are, in particular, zinc compounds, such as, for. B. zinc (II) stearate, zinc (II) n-octanoate, zinc (II) -2-ethyl-1-hexanoate, zinc (II) naphthenate or zinc (II) acetylacetonate, Tin compounds such as B. tin (II) n-octanoate, tin (II) -2-ethyl-1-hexanoate, tin (II) laurate, dibutyltin oxide, dibutyltin dichloride, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin dimaleate or dioctyltin compounds such as zirconium tin, such as zirconium . B. Zirconium (IV) -2-ethyl-1-hexanoate, zirconium (IV) neodecanoate, zirconium (IV) naphthenate or zirconium (IV) acetylacetonate, aluminum tri (ethylacetoacetate), iron ( III) chloride, potassium octoate, manganese cobalt or nickel compounds and strong acids, such as. B. trifluoroacetic acid, sulfuric acid, hydrogen chloride, hydrogen bromide, phosphoric acid or perchloric acid, or any mixture of these catalysts.

0037Suitable, albeit less preferred, catalysts for the process according to the invention are also those compounds which, in addition to the allophanatization reaction, also catalyze the trimerization of isocyanate groups to form isocyanurate structures. Such catalysts are for example in the<patcit id="pcit0016" dnum="EP0649866A"><text>EP-A-0 649 866</text></patcit> Page 4, line 7 to page 5, line 15.

0038Preferred catalysts for the process according to the invention are zinc and / or zirconium compounds of the type mentioned above. The use of zinc (II) n-octanoate, zinc (II) -2-ethyl-1-hexanoate and / or zinc is very particularly preferred - (II) stearate, zirconium (IV) n-octanoate, zirconium (IV) -2-ethyl-1-hexanoate and / or zirconium (IV) neodecanoate.

0039These catalysts are used in the process according to the invention, if at all, in an amount of 0.001 to 5% by weight, preferably 0.005 to 1% by weight, based on the total weight of the reactants A) and B) and can be used both before the start of the reaction and can also be added at any point in the reaction.

0040The process according to the invention is preferably carried out without solvents. If appropriate, however, suitable solvents which are inert to the reactive groups of the starting components can also be used. Suitable solvents are, for example, the conventional paint solvents known per se, such as. B. 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, higher substituted aromatics, such as those sold under the names Solventnaphtha, Solvesso®, Isopar®, Nappar® (Deutsche EXXON CHEMICAL GmbH, Cologne, DE) and Shellsol® (Deutsche Shell Chemie GmbH, Eschborn, DE), 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.

0041In one possible embodiment, the starting diisocyanate B) or a mixture of different starting diisocyanates, if appropriate under inert gas, such as nitrogen, and, if appropriate, in the presence of a suitable solvent of the type mentioned at a temperature between 20 and 100 ° C. The hydroxy-functional starting compound A) is then added in the amount specified above and the reaction temperature for the urethanization is optionally adjusted to a temperature of 30 to 120 ° C., preferably 50 to 100 ° C., by a suitable measure (heating or cooling). Following the urethanization reaction, ie when the NCO content theoretically corresponding to a complete conversion of isocyanate and hydroxyl groups has been reached, the allophanatization can be started, for example, without adding a catalyst by heating the reaction mixture to a temperature of 140 to 200 ° C. However, suitable catalysts of the type mentioned above are preferably used to accelerate the allophanatization reaction, with temperatures in the range from 60 to 140 ° C., preferably 80 to 120 ° C., being sufficient, depending on the type and amount of the catalyst used.

0042In another possible embodiment of the process according to the invention, the catalyst to be used, if appropriate, with either the silane component A) and / or the diisocyanate component B) is mixed in before the actual reaction begins. In this case, the urethane groups which form as intermediates and spontaneously react with the use of hydroxyurethanes A) in these already contained urethane groups to the desired allophanate structure. In this type of single-stage reaction, the starting diisocyanates B), which may contain the catalyst, are optionally under an inert gas, such as nitrogen, and, if appropriate, in the presence of a suitable solvent of the type mentioned, as a rule at temperatures which are optimal for the allophanatization in the range from 60 to 140 ° C, preferably 80 to 120 ° C, presented and reacted with the silane component A) optionally containing the catalyst.

0043However, it is also possible to add the catalyst to the reaction mixture at any time during the urethanization reaction. In this embodiment of the process according to the invention, a temperature in the range from 30 to 120 ° C., preferably from 50 to 100 ° C., is generally set for the pure urethanization reaction which takes place before the catalyst is added. After adding a suitable catalyst, the allophanatization reaction is finally carried out at temperatures from 60 to 140 ° C., preferably from 80 to 120 ° C.

0044The course of the reaction in the method according to the invention by z. B. titrimetric determination of the NCO content can be followed. After reaching the desired NCO content, preferably when the degree of allophanatization (ie the percentage of the reaction mixture which can be calculated from the NCO content of the reaction mixture which has been converted to allophanate groups and which forms intermediately from the hydroxyl groups of component A) and, if hydroxyurethanes A) is used, in these urethane groups) already present, is at least 80%, particularly preferably at least 90%, very particularly preferably after complete allophanatization, the reaction is stopped. In the case of purely thermal reaction control, this can be done, for example, by cooling the reaction mixture to room temperature. If an allophanatization catalyst of the type mentioned is preferably used, the reaction is generally stopped by adding suitable catalyst poisons, for example acid chlorides such as benzoyl chloride or isophthaloyl dichloride.

0045The reaction mixture is then preferably carried out by thin-layer distillation in a high vacuum, for example at a pressure of less than 1.0 mbar, preferably less than 0.5 mbar, particularly preferably less than 0.2 mbar, under conditions which are as gentle as possible, for example at a temperature of 100 to 200 ° C, preferably from 120 to 180 ° C, of ​​volatile constituents (excess monomeric diisocyanates, if appropriate in the preparation of the starting compounds A) excess cyclic carbonates or lactones, any solvents used and, if a catalyst poison is not used, any active catalyst).

0046The distillates obtained, which, in addition to the unreacted monomeric starting diisocyanates, contain any excess cyclic carbonates or lactones and any solvents used, and, if a catalyst poison is not used, any active catalyst which can be used, can easily be used for renewed oligomerization.

0047In a further embodiment of the process according to the invention, the volatile constituents mentioned are separated from the oligomerization product by extraction with suitable solvents which are inert toward isocyanate groups, for example aliphatic or cycloaliphatic hydrocarbons such as pentane, hexane, heptane, cyclopentane or cyclohexane.

0048Regardless of the type of work-up, clear, light-colored polyisocyanates are obtained as products of the process according to the invention, which generally have color numbers of less than 200 APHA, preferably less than 100 APHA, particularly preferably less than 80 APHA, an average NCO functionality of 2.0 to 5.0, preferably 2.4 to 4.8, particularly preferably 3.0 to 4.5, and an NCO content of 6.0 to 20.5% by weight, preferably 10.0 to 18.0 % By weight, particularly preferably 12.0 to 17.0% by weight. When using selective allophanatization catalysts, they are practically free of by-products such as e.g. B. isocyanurates, ie that in addition to isocyanate functions there is at least one silane group in almost every molecule.

0049The allophanate polyisocyanates according to the invention are valuable starting materials for the production of polyurethane plastics by the isocyanate polyaddition process.

0050Because of their relatively low viscosity, based on silane-modified polyisocyanates of the prior art, they can be used solvent-free, but if required they can also be diluted with conventional solvents, for example the above-mentioned inert lacquer solvents which may also be used in the process according to the invention.

0051The silane-modified allophanate polyisocyanates according to the invention are outstandingly suitable as hardeners for two-component polyurethane lacquers in which the usual polyether polyols, polyester polyols, polycarbonate polyols and / or polyacrylate polyols are present as reactants for the polyisocyanates as polyhydroxyl compounds. Particularly preferred reactants for the process products according to the invention are polyacrylates containing hydroxyl groups, ie polymers or Copolymers of (meth) acrylic acid alkyl esters, optionally with styrene or other copolymerizable olefinically unsaturated monomers.

0052In general, the coating agents formulated with the silane-modified allophanate polyisocyanates according to the invention, to which the auxiliaries and additives customary in the paint sector, such as, for. B. flow aids, color pigments, fillers or matting agents, can be incorporated, good paint properties even at room temperature drying. Of course, they can also be used under forced conditions at elevated temperatures or dry by baking at temperatures up to 260 ° C.

0053To control the curing rate, suitable catalysts can be used in the formulation of the coating compositions, for example the catalysts customary in isocyanate chemistry, such as. B. tert. Amines such as triethylamine, pyridine, methylpyridine, benzyldimethylamine, N, N-endoethylene piperazine, N-methylpiperidine, pentamethyldiethylenetriamine, N, N-dimethylaminocyclohexane, N, N'-dimethylpiperazine or metal salts such as iron (III) chloride, zinc chloride, zinc 2- ethylcaproate, tin (II) octanoate, tin (II) ethylcaproate, dibutyltin (IV) dilaurate, bismuth (III) -2-ethylhexanoate, bismuth (III) octoate or molybdenum glycolate. In addition, catalysts can also be used which accelerate the hydrolysis and condensation of alkoxysilane groups or their reaction with the hydroxyl groups of the polyol components used as binders. Such catalysts are, in addition to the above-mentioned isocyanate catalysts, for example also acids, such as. B. p-toluenesulfonic acid, trifluoromethanesulfonic acid, acetic acid, trifluoroacetic acid and dibutyl phosphate, bases, such as. B. N-substituted amidines such as 1,5-diazabicyclo [4.3.0] non-5-ene (DBN) and 1,5-diazabicyclo [5.4.0] undec-7-ene (DBU), but also metal salts or organometallic compounds, such as B. tetraisopropyl titanate, tetrabutyl titanate, titanium (IV) acetylacetonate, aluminum acetylacetonate, aluminum triflate or tin triflate.

0054Of course, the silane-modified allophanate polyisocyanates according to the invention can also be used in a form blocked with blocking agents known per se from polyurethane chemistry in combination with the abovementioned paint binders or paint binder components in the sense of one-component PUR stoving systems. Suitable blocking agents are, for example, diethyl malonate, acetoacetic ester, activated cyclic ketones, such as. B. Cyclopentanone-2-carboxymethyl ester and carboxyethyl ester, acetone oxime, butanone oxime, ε-caprolactam, 3,5-dimethylpyrazole, 1,2,4-triazole, dimethyl-1,2,4-triazole, imidazole, benzyl tert-butylamine or any mixtures of these blocking agents.

0055The invention therefore also relates to the use of the polyisocyanates according to the invention containing allophanate groups for the production of polyisocyanates blocked with blocking agents known from polyurethane chemistry, and to the resulting blocked polyisocyanates themselves.

0056The process products according to the invention can also with polyamines, such as. B. from<patcit id="pcit0017" dnum="EP0403921B"><text>EP-B 0 403 921</text></patcit> known polyaspartic acid derivatives, or also those polyamines whose amino groups are in blocked form, such as. As polyketimines, polyaldimines or oxazolanes can be combined. These blocked amino groups give rise to free amino groups under the influence of moisture and, in the case of oxazolanes, also free hydroxyl groups which react with crosslinking with the isocyanate groups of the silane-modified allophanate polyisocyanates.

0057The silane-modified allophanate polyisocyanates according to the invention are also suitable as crosslinking components for binders or binder components present in solution or dispersion in water, with groups which are reactive toward isocyanate groups, in particular alcoholic hydroxyl groups, in the production of aqueous two-component polyurethane systems. Due to their low viscosity, they can either be used as such, ie in hydrophobic form, but also in known methods, e.g. B. according<patcit id="pcit0018" dnum="EP0540985B"><text>EP-B 0 540 985</text></patcit>, <patcit id="pcit0019" dnum="EP0959087B"><text>EP-B 0 959 087</text></patcit> or <patcit id="pcit0020" dnum="EP1287052B"><text>EP-B 1 287 052</text></patcit>, hydrophilically modified form can be used.

0058Optionally, the coating systems formulated with the silane-modified allophanate polyisocyanates according to the invention can also be any other hydrolyzable silane compounds, such as. B. Tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, isobutyltrimethoxysilane, isobutyltriethoxysilane, octyltriethoxysilane, octyltrimethoxysilane, (3-glycidyloxypropyl) methyldiethoxysilane, (3-glycidyloxypropyl) trimethoxysilane, phenyltrimethoxysilane or phenyltriethoxysilane or mixtures of such silane compounds may be added as reactants.

0059The process products according to the invention and the reactants are present in all varnish combinations in amounts such that 0.5 to 3, preferably 0.6 to 2.0, particularly preferably 0.8 to 1.6 optionally blocked, for each isocyanate group blocked, compared to isocyanates reactive groups are eliminated.

0060If necessary, the polyisocyanate mixtures according to the invention can be mixed in minor amounts but also non-functional paint binders to achieve very special properties, for example as an additive for improving the adhesion.

0061Any substrates can be used as substrates for the coatings formulated with the aid of the silane-modified allophanate polyisocyanates according to the invention, such as, for. B. metal, wood, glass, stone, ceramic materials, concrete, hard and flexible plastics, textiles, leather and paper, which can optionally be provided with conventional primers before coating.

0062Further subjects of this invention are thus coating compositions containing the polyisocyanates bearing allophanate groups according to the invention, as well as the substrates coated with these coating compositions.

<u style="single">Examples</u>

0063Unless otherwise stated, all percentages relate to the weight. The NCO contents were determined in accordance with DIN EN ISO 11909.

0064All viscosity measurements were carried out with a Physica MCR 51 rheometer from Anton Paar Germany GmbH (Ostfildern) in accordance with DIN EN ISO 3219.

0065The Hazen color numbers were determined on a LICO 400 color measuring device from Hach Lange GmbH, Düsseldorf.

0066The OH numbers given for the starting compounds A) were calculated from the theoretical molecular weight of the ideal structure (1: 1 adduct).

Preparation of the starting compounds A)

Hydroxyurethane A1 containing silane groups)

0067221 g (1.0 mol) of 3-aminopropyltriethoxysilane were initially charged at room temperature under dry nitrogen. For this purpose, 88 g (1.0 mol) of ethylene carbonate were added with stirring over the course of 15 minutes, the mixture initially heating up to 34 ° C. due to the heat of reaction liberated, and the mixture was then stirred without further heating for 18 hours at room temperature. An amine titration with 1N HCl showed a conversion of 99.8%. 2-Hydroxyethyl [3- (triethoxysilyl) propyl] urethane was obtained as a colorless liquid.<tables id="tabl0001" num="0001"><table frame="none"><tgroup cols="2" colsep="0" rowsep="0"><colspec colnum="1" colname="col1" colwidth="39mm" /><colspec colnum="2" colname="col2" colwidth="26mm" /><tbody><row><entry>Viscosity (23 ° C):</entry><entry>69 mPas</entry></row><row><entry>OH number (calc.):</entry><entry>181 mg KOH / g</entry></row><row><entry>Molecular weight (calc.):</entry><entry>309 g / mol</entry></row></tbody></tgroup></table></tables>

Hydroxyurethane A2 containing silane groups)

0068179 g (1.0 mol) of 3-aminopropyltrimethoxysilane and 88 g (1.0 mol) of ethylene carbonate were reacted with one another by the process described for starting compound A1). The conversion (amine titration with 1N HCl) after 18 hours was 99.6%.

00692-Hydroxyethyl [3- (trimethoxysilyl) propyl] urethane was obtained as a colorless liquid.<tables id="tabl0002" num="0002"><table frame="none"><tgroup cols="2" colsep="0" rowsep="0"><colspec colnum="1" colname="col1" colwidth="39mm" /><colspec colnum="2" colname="col2" colwidth="26mm" /><tbody><row><entry>Viscosity (23 ° C):</entry><entry>245 mPas</entry></row><row><entry>OH number (calc.):</entry><entry>210 mg KOH / g</entry></row><row><entry>Molecular weight (calc.):</entry><entry>267 g / mol</entry></row></tbody></tgroup></table></tables>

Hydroxy urethane A3 containing silane groups)

0070221 g (1.0 mol) of 3-aminopropyltriethoxysilane and 102 g (1.0 mol) of propylene carbonate were reacted with one another by the process described for starting compound A1). The conversion (amine titration with 1N HCl) after 18 hours was 99.9%.

0071A mixture of 2-hydroxypropyl [3- (triethoxysilyl) propyl] urethane and 2-hydroxy-1-methylethyl [3- (triethoxysilyl) propyl] urethane was obtained as a colorless liquid.<tables id="tabl0003" num="0003"><table frame="none"><tgroup cols="2" colsep="0" rowsep="0"><colspec colnum="1" colname="col1" colwidth="39mm" /><colspec colnum="2" colname="col2" colwidth="26mm" /><tbody><row><entry>Viscosity (23 ° C):</entry><entry>86 mPas</entry></row><row><entry>OH number (calc.):</entry><entry>173 mg KOH / g</entry></row><row><entry>Molecular weight (calc.):</entry><entry>323 g / mol</entry></row></tbody></tgroup></table></tables>

Hydroxyurethane A4 containing silane groups)

0072179 g (1.0 mol) of 3-aminopropyltrimethoxysilane and 102 g (1.0 mol) of propylene carbonate were reacted with one another by the process described for starting compound A1). The conversion (amine titration with 1N HCl) after 18 hours was 99.7%.

0073A mixture of 2-hydroxypropyl [3- (trimethoxysilyl) propyl] urethane and 2-hydroxy-1-methylethyl [3- (trimethoxysilyl) propyl] urethane was obtained as a colorless liquid.<tables id="tabl0004" num="0004"><table frame="none"><tgroup cols="2" colsep="0" rowsep="0"><colspec colnum="1" colname="col1" colwidth="39mm" /><colspec colnum="2" colname="col2" colwidth="26mm" /><tbody><row><entry>Viscosity (23 ° C):</entry><entry>326 mPas</entry></row><row><entry>OH number (calc.):</entry><entry>199 mg KOH / g</entry></row><row><entry>Molecular weight (calc.):</entry><entry>281 g / mol</entry></row></tbody></tgroup></table></tables>

Hydroxyamide A5 containing silane groups)

0074221 g (1.0 mol) of 3-aminopropyltriethoxysilane and 86 g (1.0 mol) of γ-butyrolactone were reacted with one another by the process described for starting compound A1). The conversion (amine titration with 1N HCl) after 18 hours was 99.4%.

00754-Hydroxy-N- [3- (triethoxysilyl) propyl] butanamide was obtained as a colorless liquid<tables id="tabl0005" num="0005"><table frame="none"><tgroup cols="2" colsep="0" rowsep="0"><colspec colnum="1" colname="col1" colwidth="39mm" /><colspec colnum="2" colname="col2" colwidth="26mm" /><tbody><row><entry>Viscosity (23 ° C):</entry><entry>326 mPas</entry></row><row><entry>OH number (calc.):</entry><entry>199 mg KOH / g</entry></row><row><entry>Molecular weight (calc.):</entry><entry>281 g / mol</entry></row></tbody></tgroup></table></tables>

<u style="single">example 1</u>

(according to the invention)

00761680 309 g (1.0 mol) of the silane group-containing hydroxyurethane A1) were added to g (10.0 mol) of hexamethylene diisocyanate (HDI) at 80 ° C. under dry nitrogen and the mixture was stirred for 3 hours until an NCO content of 40 , 1%, corresponding to a complete urethanization, was reached. The reaction mixture was then heated to 95 ° C. and 0.5 g of zinc (II) -2-ethyl-1-hexanoate was added as an allophanatization catalyst. Due to the exothermic reaction, the temperature of the mixture rose to 110 ° C. After about 30 minutes, the NCO content of the reaction mixture was 35.9%. The catalyst was deactivated by adding 1 g of benzoyl chloride and the unreacted monomeric HDI was separated off at a temperature of 130 ° C. and a pressure of 0.1 mbar in a thin-film evaporator. 789 g of a practically colorless, clear allophanate polyisocyanate were obtained with the following characteristics:<tables id="tabl0006" num="0006"><table frame="none"><tgroup cols="3" colsep="0" rowsep="0"><colspec colnum="1" colname="col1" colwidth="36mm" /><colspec colnum="2" colname="col2" colwidth="22mm" /><colspec colnum="3" colname="col3" colwidth="68mm" /><tbody><row><entry>NCO content:</entry><entry>13,7 %</entry><entry /></row><row><entry>monomeric HDI:</entry><entry>0,03 %</entry><entry /></row><row><entry>Viscosity (23 ° C):</entry><entry>1270 mPas</entry><entry /></row><row><entry>Color number (APHA):</entry><entry>21 Hazen</entry><entry /></row><row><entry>NCO functionality:</entry><entry>> 3</entry><entry>(calculated)</entry></row><row><entry>Silane group content:</entry><entry>9,6 %</entry><entry>(calculated as SiO₃; Mol.weight = 76 g / mol)</entry></row></tbody></tgroup></table></tables>

<u style="single">Example 2</u>

(according to the invention)

0077According to the process described in Example 1, 1680 g (10.0 mol) of HDI were reacted with 267 g (1.0 mol) of the hydroxy urethane A2) containing silane groups. The allophanatization reaction was started at an NCO content of 41.0% by adding 0.5 g of zinc (II) -2-ethyl-1-hexanoate. After an NCO content of 36.7% had been reached, the reaction mixture was quenched with 1 g of benzoyl chloride and worked up as described in Example 1. 690 g of a practically colorless, clear allophanate polyisocyanate were obtained with the following characteristics:<tables id="tabl0007" num="0007"><table frame="none"><tgroup cols="3" colsep="0" rowsep="0"><colspec colnum="1" colname="col1" colwidth="36mm" /><colspec colnum="2" colname="col2" colwidth="22mm" /><colspec colnum="3" colname="col3" colwidth="68mm" /><tbody><row><entry>NCO content:</entry><entry>14,2 %</entry><entry /></row><row><entry>monomeric HDI:</entry><entry>0,06 %</entry><entry /></row><row><entry>Viscosity (23 ° C):</entry><entry>3050 mPas</entry><entry /></row><row><entry>Color number (APHA):</entry><entry>19th Hazen</entry><entry /></row><row><entry>NCO functionality:</entry><entry>> 3</entry><entry>(calculated)</entry></row><row><entry>Silane group content:</entry><entry>11,0 %</entry><entry>(calculated as SiO₃; Mol.weight = 76 g / mol)</entry></row></tbody></tgroup></table></tables>

<u style="single">Example 3</u>

(Comparison, analogous to WO 03/054049)

0078660 g (3.61 eq) of a polyisocyanurate polyisocyanate based on HDI with an NCO content of 23.0% with an NCO functionality of 3.2, a content of monomeric HDI of 0.1% and a viscosity at 23 ° C from approx. 1200 340 g (1.45 mol) of N- (n-butyl) -3-aminopropyltrimethoxysilane were added to mPas under dry nitrogen at a temperature of 100 ° C. within 30 min and the mixture was then stirred for 2 hours until an NCO content of 9 , 1%, according to a complete implementation, was reached. A silane group-containing polyisocyanate was obtained as a colorless, highly viscous resin with the following characteristics:<tables id="tabl0008" num="0008"><table frame="none"><tgroup cols="3" colsep="0" rowsep="0"><colspec colnum="1" colname="col1" colwidth="36mm" /><colspec colnum="2" colname="col2" colwidth="26mm" /><colspec colnum="3" colname="col3" colwidth="68mm" /><tbody><row><entry>NCO content:</entry><entry>9,1 %</entry><entry /></row><row><entry>monomeric HDI:</entry><entry>0,03 %</entry><entry /></row><row><entry>Viscosity (23 ° C):</entry><entry>183,000 mPas</entry><entry /></row><row><entry>Color number (APHA):</entry><entry>37 Hazen</entry><entry /></row><row><entry>NCO functionality:</entry><entry>1,9</entry><entry>(calculated)</entry></row><row><entry>Silane group content:</entry><entry>11,0 %</entry><entry>(calculated as SiO₃; Mol.weight = 76 g / mol)</entry></row></tbody></tgroup></table></tables>

<u style="single">Example 4</u>

(Comparison, analogous to WO 02/058569)

0079500 g (2.58 eq) of a polyisocyanurate polyisocyanate based on HDI with an NCO content of 21.7% with an NCO functionality of 3.5, a content of monomeric HDI of 0.1% and a viscosity at 23 ° C of about 3000 mPas were prepared under dry nitrogen at a temperature of 80 ° C within 30 min with 500 g (1.42 mol) of N- (3-trimethoxysilylpropyl) aspartic acid diethyl ester, prepared according to Example 5 <patcit id="pcit0021" dnum="EP0596360A"><text>EP 0 596 360</text></patcit>, added and then stirred for 2 hours until an NCO content of 4.9%, corresponding to a complete reaction, was reached. A silane group-containing polyisocyanate was obtained as a colorless, highly viscous resin with the following characteristics:<tables id="tabl0009" num="0009"><table frame="none"><tgroup cols="3" colsep="0" rowsep="0"><colspec colnum="1" colname="col1" colwidth="36mm" /><colspec colnum="2" colname="col2" colwidth="26mm" /><colspec colnum="3" colname="col3" colwidth="68mm" /><tbody><row><entry>NCO content:</entry><entry>4,9 %</entry><entry /></row><row><entry>monomeric HDI:</entry><entry>0,03 %</entry><entry /></row><row><entry>Viscosity (23 ° C):</entry><entry>127,000 mPas</entry><entry /></row><row><entry>Color number (APHA):</entry><entry>65 Hazen</entry><entry /></row><row><entry>NCO functionality:</entry><entry>1,6</entry><entry>(calculated)</entry></row><row><entry>Silane group content:</entry><entry>approx. 10.8%</entry><entry>(calculated as SiO₃; Mol.weight = 76 g / mol)</entry></row></tbody></tgroup></table></tables>

0080The comparison shows that the silane groups-containing polyisocyanates according to the invention from Examples 1 and 2, with a similar silane group content, have a higher isocyanate content, a significantly higher NCO functionality and in particular a considerably lower viscosity than the silane group-containing polyisocyanates of Comparative Examples 3 and 4.

<u style="single">Example 5</u>

(according to the invention)

0081According to the method described in Example 1, 1680 g (10.0 mol) of HDI were reacted with 323 g (1.0 mol) of the silane group-containing hydroxyurethane A3). The allophanatization reaction was started at an NCO content of 39.8% by adding 0.5 g of zinc (II) -2-ethyl-1-hexanoate. After an NCO content of 35.6% had been reached, the reaction mixture was quenched with 1 g of benzoyl chloride and worked up as described in Example 1. 740 g of a practically colorless, clear allophanate polyisocyanate were obtained with the following characteristics:<tables id="tabl0010" num="0010"><table frame="none"><tgroup cols="3" colsep="0" rowsep="0"><colspec colnum="1" colname="col1" colwidth="36mm" /><colspec colnum="2" colname="col2" colwidth="22mm" /><colspec colnum="3" colname="col3" colwidth="68mm" /><tbody><row><entry>NCO content:</entry><entry align="right">13,5 %</entry><entry /></row><row><entry>monomeric HDI:</entry><entry align="right">0,28 %</entry><entry /></row><row><entry>Viscosity (23 ° C):</entry><entry align="right">1680 mPas</entry><entry /></row><row><entry>Color number (APHA):</entry><entry align="right">22 Hazen</entry><entry /></row><row><entry>NCO functionality:</entry><entry align="right">> 3</entry><entry>(calculated)</entry></row><row><entry>Silane group content:</entry><entry align="right">10,3 %</entry><entry>(calculated as SiO₃; Mol.weight = 76 g / mol)</entry></row></tbody></tgroup></table></tables>

<u style="single">Example 6</u>

(according to the invention)

0082According to the process described in Example 1, 3360 g (20.0 mol) of HDI were reacted with 281 g (1.0 mol) of the hydroxyurethane A4) containing silane groups. The allophanatization reaction was started at an NCO content of 45.0% by adding 0.5 g of zinc (II) -2-ethyl-1-hexanoate. After an NCO content of 42.7% had been reached, the reaction mixture was quenched with 1 g of benzoyl chloride and worked up as described in Example 1. You got approx. 705 g of a practically colorless, clear allophanate polyisocyanate with the following characteristics:<tables id="tabl0011" num="0011"><table frame="none"><tgroup cols="3" colsep="0" rowsep="0"><colspec colnum="1" colname="col1" colwidth="36mm" /><colspec colnum="2" colname="col2" colwidth="22mm" /><colspec colnum="3" colname="col3" colwidth="68mm" /><tbody><row><entry>NCO content:</entry><entry>14,6 %</entry><entry /></row><row><entry>monomeric HDI:</entry><entry>0,21 %</entry><entry /></row><row><entry>Viscosity (23 ° C):</entry><entry>2630 mPas</entry><entry /></row><row><entry>Color number (APHA):</entry><entry>19th Hazen</entry><entry /></row><row><entry>NCO functionality:</entry><entry>> 3</entry><entry>(calculated)</entry></row><row><entry>Silane group content:</entry><entry>10,8 %</entry><entry>(calculated as SiO₃; Mol.weight = 76 g / mol)</entry></row></tbody></tgroup></table></tables>

<u style="single">Example 7</u>

(according to the invention)

0083According to the method described in Example 1, 1680 g (10.0 mol) of HDI were reacted with 307 g (1.0 mol) of the silane group-containing hydroxyamide A5). The allophanatization reaction was started at an NCO content of 39.8% by adding 0.5 g of zinc (II) -2-ethyl-1-hexanoate. After an NCO content of 35.6% had been reached, the reaction mixture was quenched with 1 g of benzoyl chloride and worked up as described in Example 1. 537 g of a practically colorless, clear allophanate polyisocyanate were obtained with the following characteristics:<tables id="tabl0012" num="0012"><table frame="none"><tgroup cols="3" colsep="0" rowsep="0"><colspec colnum="1" colname="col1" colwidth="36mm" /><colspec colnum="2" colname="col2" colwidth="22mm" /><colspec colnum="3" colname="col3" colwidth="68mm" /><tbody><row><entry>NCO content:</entry><entry>12,1 %</entry><entry /></row><row><entry>monomeric HDI:</entry><entry>0,08 %</entry><entry /></row><row><entry>Viscosity (23 ° C):</entry><entry>5270 mPas</entry><entry /></row><row><entry>Color number (APHA):</entry><entry>24th Hazen</entry><entry /></row><row><entry>NCO functionality:</entry><entry>2,0</entry><entry>(calculated)</entry></row><row><entry>Silane group content:</entry><entry>14,1 %</entry><entry>(calculated as SiO₃; Mol.weight = 76 g / mol)</entry></row></tbody></tgroup></table></tables>

<u style="single">Example 8</u>

(according to the invention)

00842222 g (10.0 mol) of 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (IPDI) were reacted with 309 g (1.0 mol) of the silane group-containing hydroxyurethane A1) by the process described in Example 1 . The allophanatization reaction was started at an NCO content of 31.5% by adding 0.4 g of stannous (II) -2-ethyl-1-hexanoate. After an NCO content of 28.2% had been reached, the reaction mixture was quenched with 1 g of benzoyl chloride and the unreacted monomeric IPDI was separated off at a temperature of 160 ° C. and a pressure of 0.1 mbar in a thin-film evaporator. 939 g of a viscous, pale yellow allophanate polyisocyanate were obtained, which after dissolving in 1-methoxypropyl-2-acetate as a 70 percent solution had the following characteristics:<tables id="tabl0013" num="0013"><table frame="none"><tgroup cols="3" colsep="0" rowsep="0"><colspec colnum="1" colname="col1" colwidth="36mm" /><colspec colnum="2" colname="col2" colwidth="20mm" /><colspec colnum="3" colname="col3" colwidth="68mm" /><tbody><row><entry>NCO content:</entry><entry>8,4 %</entry><entry /></row><row><entry>monomeric IPDI:</entry><entry>0,33 %</entry><entry /></row><row><entry>Viscosity (23 ° C):</entry><entry>940 mPas</entry><entry>(70% in MPA)</entry></row><row><entry>Color number (APHA):</entry><entry>31 Hazen</entry><entry /></row><row><entry>NCO functionality:</entry><entry>> 3</entry><entry>(calculated)</entry></row><row><entry>Silane group content:</entry><entry>about 5.7%</entry><entry>(calculated as SiO₃; Mol.weight = 76 g / mol)</entry></row></tbody></tgroup></table></tables>

<u style="single">Example 9</u>

(Comparison, analogous to EP-A 1273640)

0085500 g (1.39 val) of a polyisocyanurate polyisocyanate based on IPDI, 70 percent dissolved in 1-methoxypropyl-2-acetate (MPA), with an NCO content of 11.7%, an NCO functionality of 3.3, one The monomeric IPDI content of 0.3% and a viscosity at 23 ° C. of approximately 5010 mPas were diluted with a further 42.9 g of MPA and under dry nitrogen at a temperature of 50 ° C. within one hour with 100.0 g (0.23 mol) bis (3-triethoxysilylpropyl) amine added. The mixture was then stirred for one hour until an NCO content of 7.5%, corresponding to a complete reaction, had been reached. A light-colored silane group-containing polyisocyanate was obtained in the form of a 70 percent solution in 1-methoxypropyl-2-acetate, which had the following characteristics:<tables id="tabl0014" num="0014"><table frame="none"><tgroup cols="3" colsep="0" rowsep="0"><colspec colnum="1" colname="col1" colwidth="36mm" /><colspec colnum="2" colname="col2" colwidth="22mm" /><colspec colnum="3" colname="col3" colwidth="68mm" /><tbody><row><entry>NCO content:</entry><entry align="right">7,5 %</entry><entry /></row><row><entry>monomeric IPDI:</entry><entry align="right">0,22 %</entry><entry /></row><row><entry>Viscosity (23 ° C):</entry><entry align="right">2170 mPas</entry><entry>(70% in MPA)</entry></row><row><entry>Color number (APHA):</entry><entry align="right">26 Hazen</entry><entry /></row><row><entry>NCO functionality:</entry><entry align="right">2,7</entry><entry>(calculated)</entry></row><row><entry>Silane group content:</entry><entry align="right">5.6%</entry><entry>(calculated as SiO₃; Mol.weight = 76 g / mol)</entry></row></tbody></tgroup></table></tables>

0086The comparison shows that the IPDI polyisocyanate according to the invention containing silane groups from Example 8, with a similar content of silane groups, has a higher isocyanate content, a significantly higher NCO functionality and a lower viscosity than the silane group-containing polyisocyanate from Comparative Example 9.

<u style="single">Example 10</u>

(according to the invention)

0087According to the process described in Example 1, 2620 g (10.0 mol) of 4,4'-diisocyanatodicyclohexylmethane were reacted with 309 g (1.0 mol) of the silane group-containing hydroxyurethane A1). The allophanatization reaction was started at an NCO content of 37.2% by adding 0.4 g of stannous (II) -2-ethyl-1-hexanoate. After an NCO content of 24.4% had been reached, the reaction mixture was quenched with 1 g of benzoyl chloride and the unreacted monomeric 4,4'-diisocyanatodicyclohexylmethane was separated off at a temperature of 170 ° C. and a pressure of 0.1 mbar in a thin-film evaporator. 1043 g of a viscous, yellowish allophanate polyisocyanate were obtained, which, after being dissolved in 1-methoxypropyl-2-acetate, had the following characteristics as a 70 percent solution:<tables id="tabl0015" num="0015"><table frame="none"><tgroup cols="3" colsep="0" rowsep="0"><colspec colnum="1" colname="col1" colwidth="75mm" /><colspec colnum="2" colname="col2" colwidth="22mm" /><colspec colnum="3" colname="col3" colwidth="68mm" /><tbody><row><entry>NCO content:</entry><entry>7,2 %</entry><entry /></row><row><entry>monomeric 4,4'-diisocyanatodicyclohexylmethane:</entry><entry valign="bottom">0,41 %</entry><entry /></row><row><entry>Viscosity (23 ° C):</entry><entry>1145 mPas</entry><entry>(70% in MPA)</entry></row><row><entry>Color number (APHA):</entry><entry>37 Hazen</entry><entry /></row><row><entry>NCO functionality:</entry><entry>> 3</entry><entry>(calculated)</entry></row><row><entry>Silane group content:</entry><entry>5.1%</entry><entry>(calculated as SiO₃; Mol.weight = 76 g / mol)</entry></row></tbody></tgroup></table></tables>