EP4175820A1

EP4175820A1 - Coatings from polyisocyanurate coatings (rim) and their use in injection molding processes

Info

Publication number: EP4175820A1
Application number: EP21735950.4A
Authority: EP
Inventors: Jan Weikard; Yvonne REIMANN; Florian Golling; Frank Richter; Michael Glawe; Richard MEISENHEIMER; Holger Mundstock; Dirk Achten
Original assignee: Covestro Deutschland AG
Current assignee: Covestro Deutschland AG
Priority date: 2020-07-02
Filing date: 2021-06-25
Publication date: 2023-05-10
Also published as: WO2022002787A1; US20230211530A1; KR20230033654A; CN115768616A

Abstract

The invention relates to the use of polyisocyanate compositions and trimerization catalysts for producing coatings by reaction injection molding, to coatings obtained by this use and to correspondingly coated workpieces.

Description

COATINGS MADE OF POLYISOCYANURATE COATINGS (RIM) AND THEIR APPLICATION IN INJECTION MOLDING PROCESSES

The present invention relates to the use of polyisocyanate compositions and trimerization catalysts for the production of coatings by reaction injection molding, the coatings obtained through this use and correspondingly coated workpieces.

The crosslinking of polyisocyanates to form polyisocyanurate plastics is described, for example, in WO 2016/170058 or WO 2016/170059. WO 2018/073303 describes the production of coatings from reaction mixtures with a large excess of isocyanate groups over isocyanate-reactive groups.

A well-known process for building up coatings is reaction injection molding. Here, a workpiece to be coated is introduced into a mold which is dimensioned such that a cavity is present between the inside of the mold and the surface of the workpiece, the width of which corresponds to the layer thickness of the coating to be produced. In the manufacture of workpieces, this method offers advantages in terms of production technology, since the injection of the coating agent into a mold can be carried out more easily and quickly than building up a coating by spraying, dipping or brushing. This is especially true when the workpiece to be coated has a more complex three-dimensional shape. Reaction injection molding can particularly advantageously be combined with the production of a plastic component to be coated by producing the plastic component in a first mold and then transferring it directly to a further mold in which the coating is applied. It is also possible to change the geometry of the first mold, for example by moving part of the mold, in such a way that a cavity for the coating agent is created between the workpiece and the inside of the mold. Up to now, two processes in particular have been used industrially for reaction injection molding:

In one method, polyurethane coatings are produced by injecting a mixture of a polyol, a polyisocyanate and a urethanization catalyst into the gap. In order to achieve sufficiently short cycle times, systems are required that cure quickly. This requires, especially when using aliphatic isocyanate and hydroxyl compounds, the use of catalysts of high activity in very large amounts. These large amounts of highly active catalysts can reduce the service life of the coating because they remain in the product and often also catalyze hydrolysis or other degradation processes that destroy the coating in the long term. In addition, it is technically difficult to achieve uniform mixing of a multicomponent and fast-curing system in a narrow gap, all the more so when components that are poorly compatible with one another, such as trimer of hexamethylene diisocyanate and branched polyester polyols, are to be used. In addition, if the correct mixing ratio of the reactants is not adhered to, the material properties deteriorate, for example due to incompletely reacted reactants, which mean that demolding is not possible without leaving residues on the tool.

The other method is based on the formation of polyureas. Here, the required high reaction rates can be achieved quite easily due to the high reactivity of isocyanates towards amines. However, the coatings produced in this way are less scratch-resistant than comparable polyurethane coatings and are therefore unsuitable for a number of applications.

There is thus a need for a coating system for reaction injection molding that enables short cycle times through rapid curing without large amounts of catalysts, is insensitive to mixing errors and at the same time enables the production of coatings with superior application properties.

This object is achieved by the embodiments disclosed in the patent claims and further below in this description.

In a first embodiment, the present invention relates to the use of a reaction mixture with a molar ratio of isocyanate groups to isocyanate-reactive groups of at least 3: 1 for coating workpieces by reaction injection molding, the reaction mixture a) at least one polyisocyanate composition A, and b) at least one Contains trimerization catalyst B and at least 30 mol% of the free isocyanate groups present in the reaction mixture are converted to isocyanurate groups.

Reaction mixture

The reaction mixture according to the invention contains the constituents defined above in a mixing ratio which enables the polyisocyanate A to cure to form a polyisocyanurate plastic. The components are mixed and are reactive with the temperature increase defined below in this application.

The molar ratio of isocyanate groups to isocyanate-reactive groups in the reaction mixture is at least 3: 1, preferably at least 5: 1. The term "isocyanate-reactive groups" in the present application includes epoxy, hydroxyl, carboxyl, amino and Understood thiol groups. The study on which the present invention is based has shown that reaction mixtures with a stoichiometric ratio of isocyanate groups to isocyanate-reactive groups of at least 3: 1 have noticeably better performance properties than reaction mixtures which do not achieve this value.

These properties are imparted by the isocyanurate groups that are formed. Therefore, in a preferred embodiment of the present invention, at least 40 mol%, preferably at least 50 mol% and most preferably at least 60 mol% of the free isocyanate groups present in the reaction mixture are converted to isocyanurate groups.

If the viscosity of the reaction mixture is too high for use, solvents can be added to adjust the viscosity. A solvent is characterized in that it has no isocyanate-reactive groups. A solvent can escape from the coating, but can also remain in the film and act as a plasticizer there. Suitable solvents are the solvents known to those skilled in the art for diluting polyisocyanates, preferably aliphatic acetates, aromatic hydrocarbons, esters, ethers and polyethers, glycol ethers and water. Water, butyl acetate, ethyl acetate, 1-methoxy-2-propyl acetate, butanone, solvent naphtha, xylene and toluene are particularly preferred. Since organic solvents which contain neither isocyanate groups nor isocyanate-reactive groups are released from the coating, the content of organic solvents in the reaction mixture is preferably limited. The reaction mixture according to the invention therefore contains a maximum of 10% by weight, preferably a maximum of 5% by weight and more preferably a maximum of 2% by weight of organic solvent which contains neither isocyanate groups nor isocyanate-reactive groups.

The viscosity of the reaction mixture in the application is preferably at most 10,000 mPas, preferably at most 5,000 mPas, even more preferably at most 2,500 mPas and most preferably 1,000 mPas at the injection temperature determined in accordance with DIN EN ISO 3219 / B (edition of October 1, 1994) at a Shear rate of 100 s ¹ . Typical injection temperatures are 20-140 ° C, preferably 30-100 ° C and particularly preferably 40-90 ° C, and very particularly preferably 50-60 ° C. If the reaction mixture contains oligomeric polyisocyanates as defined below in this application, its viscosity can be above the aforementioned values. In these cases, the viscosity can be reduced by using monomeric polyisocyanates as reactive thinners.

Polyisocyanate Composition A

The term "polyisocyanate composition A" denotes the entirety of all compounds contained in the reaction mixture which contain at least one isocyanate group per molecule Has proportion of compounds with an average of at least two isocyanate groups per molecule in order to cause crosslinking of the reaction mixture. As long as this criterion is met, the presence of compounds with an average of one isocyanate group per molecule is harmless.

The term “polyisocyanate”, as used here, is a collective name for compounds which contain two or more isocyanate groups in the molecule (the person skilled in the art understands this to mean free isocyanate groups with the general structure -N = C = 0). Simplest and most important representatives These polyisocyanates are the diisocyanates. These have the general structure 0 = C = NRN = C = 0, where R usually stands for aliphatic, alicyclic, araliphatic and / or aromatic radicals. In this application, the term "polyisocyanate A" stands for the entirety all compounds contained in the reaction mixture with an average of at least two isocyanate groups per molecule. The polyisocyanate A can thus consist of a single polyisocyanate. But it can also be a mixture of several different polyisocyanates. In the context of the embodiments defined below, the polyisocyanate A can also contain admixtures of isocyanates with an average functionality of less than two.

A large number of polymers (e.g. polyurethanes, polyureas and polyisocyanurates) and low molecular weight compounds (e.g. those with uretdione, isocyanurate, allophanate, biuret, iminooxadiazinedione and / or oxadiazinetrione structure) are produced from polyisocyanates.

In this application, the term "polyisocyanates" refers to monomeric and / or oligomeric polyisocyanates. To understand many aspects of the invention, however, it is important to distinguish between monomeric diisocyanates and oligomeric polyisocyanates. When "oligomeric polyisocyanates" are used in this application, then polyisocyanates are meant which are built up from at least two monomeric diisocyanate molecules, ie they are compounds which represent or contain a reaction product of at least two monomeric diisocyanate molecules.

The production of oligomeric polyisocyanates from monomeric diisocyanates is also referred to here as modification of monomeric diisocyanates. This “modification”, as used here, means the reaction of monomeric diisocyanates, optionally other isocyanate-reactive molecules, to give oligomeric polyisocyanates with a uretdione, isocyanurate, allophanate, biuret, iminooxadiazinedione and / or oxadiazinetrione structure.

For example, flexamethylene 1,6-diisocyanate (HDI) is a "monomeric diisocyanate" because it contains two isocyanate groups and is not a reaction product of at least two polyisocyanate molecules: HDI

In contrast, reaction products of at least two HDI molecules which still have at least two isocyanate groups are "oligomeric polyisocyanates" within the meaning of the invention. Representatives of such "oligomeric polyisocyanates" are, based on the monomeric HDI, for example the HDI isocyanurate and the HDI biuret , each made up of three monomeric HDI molecules:

HDI isocyanurate HDI biuret

(idealized structural formulas)

The proportion by weight of isocyanate groups based on the total amount of polyisocyanate composition A is preferably at least 5% by weight. More preferably at least 10% by weight.

In principle, monomeric and oligomeric polyisocyanates are equally suitable for use in the reaction mixture according to the invention. Consequently, the polyisocyanate composition A can consist essentially of monomeric polyisocyanates or essentially of oligomeric polyisocyanates. However, it can also contain oligomeric and monomeric polyisocyanates in any mixing ratio.

In a preferred embodiment of the invention, the polyisocyanate composition A used as starting material is low in monomers (i.e. low in monomeric diisocyanates) and already contains oligomeric polyisocyanates. The terms “low in monomer” and “low in monomeric diisocyanates” are used synonymously in relation to the polyisocyanate composition A.

Particularly practical results are obtained when the polyisocyanate composition A has a proportion of monomeric diisocyanates of not more than 20% by weight, in particular not more than 15% by weight or not more than 10% by weight, based in each case on the weight of the polyisocyanate composition A. The polyisocyanate composition preferably has A has a monomeric diisocyanate content of not more than 5% by weight, preferably not more than 2.0% by weight, particularly preferably not more than 1.0% by weight, based in each case on the weight of the polyisocyanate composition A. Particularly simple and safe processing is ensured if the polyisocyanate composition A is essentially free from monomeric diisocyanates. Essentially free here means that the content of monomeric diisocyanates is at most 0.5% by weight, particularly preferably even below 0.10%, based on the weight of the polyisocyanate composition A.

According to a particularly preferred embodiment of the invention, the polyisocyanate composition A consists entirely or at least 80, 85, 90, 95, 98, 99 or 99.5% by weight, based in each case on the weight of the polyisocyanate composition A, of oligomeric polyisocyanates. A content of oligomeric polyisocyanates of at least 99% by weight is preferred here. This oligomeric polyisocyanate content relates to polyisocyanate composition A as provided. That is, the oligomeric polyisocyanates are not formed as an intermediate product during the process according to the invention, but are already present in the polyisocyanate composition A used as starting material at the beginning of the reaction.

Polyisocyanate compositions which are low in monomer or essentially free from monomeric isocyanates can be obtained by carrying out at least one further process step in each case to separate off the unreacted excess monomeric diisocyanates after the actual modification reaction. This separation of monomers can be carried out in a particularly practical manner by methods known per se, preferably by thin-film distillation in a high vacuum or by extraction with suitable solvents which are inert towards isocyanate groups, for example aliphatic or cycloaliphatic hydrocarbons such as pentane, hexane, heptane, cyclopentane or cyclohexane.

According to a preferred embodiment of the invention, the polyisocyanate A is obtained by modifying monomeric diisocyanates with subsequent removal of unreacted monomers.

According to a particular embodiment of the invention, however, a low-monomer polyisocyanate composition A contains a monomeric foreign diisocyanate. Here, “monomeric foreign diisocyanate” means that it differs from the monomeric diisocyanates that were used to prepare the oligomeric polyisocyanates contained in polyisocyanate composition A.

An addition of monomeric external diisocyanate can be advantageous in order to achieve special technical effects, such as, for example, a special hardness. Particularly practical results are obtained, if the isocyanate A has a proportion of monomeric external diisocyanate of at most 50% by weight, in particular at most 30% by weight or at most 15% by weight, based in each case on the weight of the polyisocyanate composition A. The polyisocyanate composition A preferably has a content of monomeric foreign diisocyanate of not more than 10% by weight, preferably not more than 2.0% by weight, particularly preferably not more than 1.0% by weight, based in each case on the weight of the polyisocyanate composition A.

According to a further particular embodiment of the process according to the invention, the polyisocyanate composition A contains monomeric isocyanates with an isocyanate functionality greater than two, i.e. with more than two isocyanate groups per molecule. The addition of monomeric isocyanates with an isocyanate functionality greater than two has proven to be advantageous in order to influence the network density of the coating. Particularly practical results are obtained when the polyisocyanate composition A contains a proportion of monomeric isocyanates with an isocyanate functionality greater than two in the polyisocyanate composition A of at most 20% by weight, in particular at most 15% by weight or at most 10% by weight on the weight of the polyisocyanate composition A. The polyisocyanate composition A preferably has a content of monomeric monoisocyanates or monomeric isocyanates with an isocyanate functionality greater than two of at most 5% by weight, preferably at most 2.0% by weight, particularly preferably at most 1.0% by weight, in each case based on the weight of the polyisocyanate composition A on. Preferably, no monomeric monoisocyanate or monomeric isocyanate with an isocyanate functionality greater than two is also used in the trimerization reaction according to the invention. Monomeric isocyanates with an isocyanate functionality> 2 are, for example, triisocyanatononane and PMDI.

According to the invention, the oligomeric polyisocyanates can in particular have uretdione, isocyanurate, allophanate, biuret, iminooxadiazinedione and / or oxadiazinetrione structure. According to one embodiment of the invention, the oligomeric polyisocyanates have at least one of the following oligomeric structure types or mixtures thereof:

Uretdione isocyanurate allophanate biuret iminooxadiazinedione oxadiazinetrione

According to a preferred embodiment of the invention, a polyisocyanate composition A is used whose isocyanurate structural content is at least 50 mol%, preferably at least 60 mol% %, more preferably at least 70 mol%, even more preferably at least 80 mol%, even more preferably at least 90 mol% and particularly preferably at least 95 mol% based on the sum of the oligomeric structures present from the group consisting of uretdione -, isocyanurate, allophanate, biuret, iminooxadiazinedione and oxadiazinetrione structure in the polyisocyanate composition A.

According to a further preferred embodiment of the invention, a polyisocyanate composition A is used in the process according to the invention which, in addition to the isocyanurate structure, contains at least one further oligomeric polyisocyanate with uretdione, biuret, allophanate, iminooxadiazinedione and oxadiazinetrione structure and mixtures thereof.

The proportions of uretdione, isocyanurate, allophanate, biuret, iminooxadiazinedione and / or oxadiazinetrione structure in polyisocyanate composition A can be determined, for example, by NMR spectroscopy. 13C-NMR spectroscopy, preferably proton-decoupled, can preferably be used here, since the oligomeric structures mentioned provide characteristic signals.

Regardless of the underlying oligomeric structure (uretdione, isocyanurate, allophanate, biuret, iminooxadiazinedione and / or oxadiazinetrione structure), an oligomeric polyisocyanate composition A to be used in the process according to the invention preferably has an (average) NCO functionality of 2.0 to 5 , 0, preferably from 2.3 to 4.5.

Particularly practical results are obtained when the polyisocyanate composition A to be used according to the invention has an isocyanate group content of 8.0 to 28.0% by weight, preferably from 14.0 to 25.0% by weight, based in each case on the weight of the Polyisocyanate composition A, has.

Production processes for the oligomeric polyisocyanates to be used according to the invention in the polyisocyanate composition A and having a uretdione, isocyanurate, allophanate, biuret, iminooxadiazinedione and / or oxadiazinetrione structure are described, for example, in J. Prakt. Chem. 336 (1994) 185-200, in DE-A 1 670666, DE-A 1954093, DE-A 2414413, DE-A 2452532, DE-A 2641380, DE-A 3700209, DE-A 3900 053 and DE- A 3 928 503 or in EP-A 0336 205, EP A 0339396 and EP-A 0798 299.

According to an additional or alternative embodiment of the invention, the polyisocyanate composition A is defined in that it contains oligomeric polyisocyanates which are particularly preferred from monomeric diisocyanates regardless of the type of modification reaction used while maintaining a degree of oligomerization of 5 to 45%, preferably 10 to 40% 15 to 30%. The "degree of oligomerization" is to be understood as the percentage of isocyanate groups originally present in the starting mixture which is to be understood during the Manufacturing process with the formation of urethane, uretdione, isocyanurate, allophanate, biuret, iminooxadiazinedione and / or oxadiazinetrione structures is consumed.

Suitable polyisocyanates for producing the polyisocyanate composition A to be used according to the invention and the monomeric and / or oligomeric polyisocyanates contained therein are any polyisocyanates accessible in various ways, for example by phosgenation in the liquid or gas phase or by phosgene-free route, such as, for example, by thermal urethane cleavage. Particularly good results are obtained when the polyisocyanates are monomeric diisocyanates. Preferred monomeric diisocyanates are those which have a molecular weight in the range from 140 to 400 g / mol, with aliphatically, cycloaliphatically, araliphatically and / or aromatically bound isocyanate groups, such as. B. 1,4-diisocyanatobutane (BDI), 1,5-diisocyanatopentane (PDI), 1,6-diisocyanatohexane (HDI), 2-methyl-1,5-diisocyanatopentane, 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, l-isocyanato-3,3,5-trimethyl-5-isocyanatomethyl-cyclohexane

(Isophorone diisocyanate; IPDI), l-isocyanato-l-methyl-4 (3) -isocyanatomethylcyclohexane, 2,4'- and 4,4'-diisocyanatodicyclohexylmethane (H12MDI), 1,3- and 1,4-bis (isocyanatomethyl) cyclohexane, bis-

(isocyanatomethyl) norbornane (NBDI), 4,4'-diisocyanato-3,3'-dimethyldicyclohexylmethane, 4,4'-diisocyanato-3,3 ', 5,5'-tetramethyl-dicyclohexylmethane, 4,4'-diisocyanato -l, l'-bi (cyclohexyl), 4,4'-diisocyanato-3,3'-dimethyl-l, l'-bi (cyclohexyl), 4,4'-diisocyanato-2,2 ', 5.5 '-tetra-methyl-l, l'-bi (cyclohexyl), 1,8-diisocyanato-p-menthane, 1,3-diisocyanato-adamantane, 1,3-dimethyl-5,7-diisocyanatoadamantane, 1,3- and 1,4-bis (iso-cyanoatomethyl) benzene (xylylene diisocyanate; XDI), 1,3- and 1,4-bis (l-isocyanato-l-methyhethyl) benzene (TMXDI) and bis (4- (l -isocyanato-1-methylethyl) phenyl) carbonate, 2,4- and 2,6-diisocyanatotoluene (TDI), 2,4'- and 4,4'-diisocyanatodiphenylmethane (MDI), 1,5-diisocyanatonaphthalene and any mixtures such diisocyanates. Further, likewise suitable diisocyanates can also be found, for example, in Justus Liebigs Annalen der Chemie Volume 562 (1949) pp. 75-136.

Suitable monomeric monoisocyanates which can optionally be used in polyisocyanate composition A are, for example, n-butyl isocyanate, n-amyl isocyanate, n-hexyl isocyanate, n-heptyl isocyanate, n-octyl isocyanate, undecyl isocyanate, dodecyl isocyanate, tetradecyl isocyanate, cetyl isocyanate, stearyl isocyanate, cyclohexyl isocyanate, cyclohexyl isocyanate, 3- or 4-methylcyclohexyl isocyanate or any mixtures of such monoisocyanates. An example of a monomeric isocyanate with an isocyanate functionality greater than two, which can optionally be added to isocyanate component A, is 4-isocyanatomethyl-1,8-octane diisocyanate (triisocyanatononane; TIN). According to one embodiment of the invention, the polyisocyanate composition A contains at most 30% by weight, in particular at most 20% by weight, at most 15% by weight, at most 10% by weight, at most 5% by weight or at most 1% by weight %, in each case based on the weight of the polyisocyanate composition A, of aromatic polyisocyanates. As used herein, "aromatic polyisocyanate" means a polyisocyanate which has at least one aromatically bound isocyanate group.

Aromatically bound isocyanate groups are understood to mean isocyanate groups which are bound to an aromatic hydrocarbon radical.

According to a further embodiment of the invention, the polyisocyanate composition A consists of at least 70, 80, 85, 90, 95, 98 or 99% by weight, based in each case on the weight of the polyisocyanate composition A, of polyisocyanates which are exclusively aliphatically and / or cycloaliphatically bound Have isocyanate groups. Practical tests have shown that particularly good results can be achieved with polyisocyanate compositions A in which the isocyanates contained therein exclusively have aliphatically and / or cycloaliphatically bound isocyanate groups.

Aliphatically or cycloaliphatically bound isocyanate groups are understood to mean isocyanate groups which are bound to an aliphatic or cycloaliphatic hydrocarbon radical. According to another preferred embodiment of the process according to the invention, a polyisocyanate A is used which consists of or contains one or more oligomeric polyisocyanates, the one or more oligomeric polyisocyanates exclusively having aliphatically and / or cycloaliphatically bound isocyanate groups.

According to a particularly preferred embodiment of the process according to the invention, a polyisocyanate composition A is used which consists of or contains one or more oligomeric polyisocyanates, the one or more oligomeric polyisocyanates based on 1,4-diisocyanatobutane (BDI), 1,5-diisocyanatopentane (PDI), 1,6-diisocyanatohexane (HDI), isophorone diisocyanate (IPDI) or 4,4'-diisocyanatodicyclohexylmethane (H12MDI) or mixtures thereof.

Blocked polyisocyanates

In one embodiment of the present invention, at least some of the polyisocyanates contained in the polyisocyanate composition A are blocked. “Blocking” means that the isocyanate groups of a polyisocyanate have reacted with another compound, the blocking agent, so that the blocked isocyanate groups are no longer those for free Isocyanate groups show typical reactivity. Only thermal activation of the blocked isocyanate leads to an increase in the reactivity towards isocyanate-reactive groups or free isocyanate groups, so that polymerization can take place. Suitable blocking agents are generally known to the person skilled in the art.

According to the invention, at least one compound is selected from the group consisting of alcohols, phenols, pyridinoies, thiophenols, quinolinoies, mercaptopyridines, quinolinoies, amides, imides, imidazoles, imidazolines, lactams, oximes, pyrazoles, triazoles, malonic esters, acetoacetic esters, acetyl ketones and cyclopentyl ketones -Alkyl esters, used as blocking agents. More preferably, the blocking takes place with a compound selected from the group consisting of mercaptopyridines, quinolinoies, amides, imides, imidazoles, imidazolines, lactams, oximes, pyrazoles, triazoles, malonic esters, acetoacetic esters, acetyl ketones and cyclopentanone-2-alkyl esters. At least one cyclopentanone-2-alkyl ester is very particularly preferably used.

Preferred lactams, amides and imides are selected from the group consisting of N-methylacetamide, acetanilide, g-butyrolactam, x-enantholactam, d-valerolactam, laurolactam, e-caprolactam, 5-methyl-2-piperidone, 3,6-dialkyl 2,5-piperazidinone or phthalimide. A particularly preferred lactam is e-caprolactam.

Preferred oximes are selected from the group consisting of 2-butanone oxime, 3-methyl-2-butanone oxime, 3,3-dimethyl-2-butanone oxime, 4-methyl-2-pentanone oxime, 5-methyl-2-hexanone oxime, 2-heptanone oxime , 4,6-dimethyl-2-heptanone oxime, 3-ethyl-2-nonoxime, 2,4-dimethyl-3-pentanone oxime, 2,6-dimethyl-4-heptanone oxime, formal doxime, acetophenone oxime, dieth glyoxime, pentanone oxime, flexanon oxime, cyclohexanone oxime , 2,2,6,6-tetramethylcyclohexanone oxime, 2, 2,4,4-

Tetramethylcyclobutane-l, 3-dione-l-oxime and flydroxamic acid. A particularly preferred oxime is 2-butanone oxime.

Suitable phenols, quinolines and pyridinoies include the esters of 2-hydroxybenzoic acid and 4-hydroxybenzoic acid, such as methyl 2-hydroxybenzoate, ethyl 2-hydroxybenzoate, 2-ethylhexyl-2-hydroxybenzoate, methyl 4-hydroxybenzoate, ethyl 4-hydroxybenzoate -hydroxybenzoate or 2-ethylhexyl-4-hydroxybenzoate, 2- [(dimethylamino) methyl] phenol, 2 - [(dimethylamino) methyl] -4-nonylphenol, phenol, 2,3,5-trimethylphenol, 2,3,6- Trimethylphenol, 2,4,6-trimethylphenol, o-cresol, m-cresol, p-cresol, 2-tert-butylphenol, 4-tert-butylphenol, 2-hydroxymethyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxymethyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxyquinoline, 8-hydroxyquinoline, 2-hydroxypyridine, 3-hydroxypyridine, 2-hydroxymethylpyridine, 3-hydroxymethylpyridine, 2-chloro-3-hydroxypyridine and para-cresol-formaldehyde resins and phenolic terpene resins and phenolic terpene resins. Preferred phenols are selected from the group consisting of phenol, 2,3,5-trimethylphenol, 2,3,6-trimethylphenol, 2,4,6-trimethylphenol, o-cresol, m-cresol, p-cresol, 2-tert -Butylphenol and 4-tert-butylphenol.

Suitable alcohols include, for example, linear and branched aliphatic alcohols such as isopropanol, n-butanol, sec-butanol, tert-butanol, n-pentanol, 2,2-dimethyl-1-propanol, n-hexanol, 2-ethylhexanol, 1-octanol or 2-0ctanol, cyclohexanol, furfuryl alcohol, monoethers of ethylene glycol, such as 2-methoxyethanol, 2-ethoxyethanol, 2-propoxyethanol, 2-butoxyethanol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, N-, diethylene glycol monobutyl ether or ethanol, 2-ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, N-, 2-ethylene glycol monobutyl ether, N-, 2-ethylene glycol monobutyl ether, N-, 2-ethylene glycol monobutyl ether or ethanol Dibutyl glycolamide, N-hydroxysuccinimide, 2-morpholinoethanol, 2,2-dimethyl-4-hydroxymethyl-1,3-dioxolane, 12-hydroxystearic acid or 3-oxazolidine ethanol.

Suitable imidazoles, imidazolines, pyrazoles and triazoles are, for example, 2-methylimidazole, 2-ethylimidazole, 2-isopropylimidazole, 2-ethyl-4-methylimidazole, 2,4-dimethylimidazoline, 4-methylimidazoline, 2-phenylimidazoline, 4-methyl-2- phenylimidazoline, 3-methylpyrazole, 3,5-dimethylpyrazole, 1,2,4-triazole or benzotriazole. Preferred pyrazole is 3,5-dimethylpyrazole. Malonic acid esters, acetoacetic acid esters and acetyl ketona include, for example, dimethyl malonate, diethyl malonate, diisopropyl malonate, tert-butyl methyl malonate, di-tert-butyl malonate, isopropylidene malonate, methyl acetoacetate, ethyl aetoacetate, isoprpylacetoacetate, 2, 4 oxy acetyl acetonate, isoprpylacetoacetate, 2, 4 oxy acetyl acetonate, acetyl acetonate, isopropyl acetonate, 2, 4, anyl methoxyacetonate, isoprpylacetoacetate, acetylacetone acetone, isoprpylacetoacetate, 2, 4, oxy methylacetone, acetone, acetone, acetone, acetone, acetone, acetone, acetone, acetone, acetone. Preferred malonates are diethyl malonate and dimethyl malonate.

Preferred secondary amines are selected from the group consisting of diisopropylamine, dibutylamine, di-tert-butylamine, N-methyl-tert-butylamine, tert-butylbenzylamine, 2,2,4-trimethylhexamethyleneamine, 2,2,5-trimethylhexamethyleneamine, N- Methylhexylamine, N-isopropylcyclohexylamine, dicyclohexylamine, bis (3,3,5-trimethylcyclohexyl) -amine, 3-tert-butylaminomethylpropionate, piperidine, 2,6-dimethylpiperidine, 2,2,6,6-tetramethylpiperidine, 4- (dimethylamino) -2,2,6,6-tetramethylpiperidine, 2,2,6,6-tetramethyl-4-piperidon-bis (2,2,6,6-

Tetramethylpieridinyl) amine, N-methylaniline, diphenylamine or N-phenylnaphthalene.

Diisopropylamine, tetramethylpiperidine and N-methyl-tert-butylamine, tert-butylbenzylamine, n-dibutylamine and 3-tert-butylaminomethylpropionate are particularly preferred.

Cyclopentanone-2-alkyl ester, cyclopentanone-2-methyl ester, cyclopentanone-2-ethyl ester, cyclopentanone-2-propyl ester, cyclopentanone-2-butyl ester and cyclopentanone-2-pentylyl ester are preferred. Cyclopentanone-2-methyl ester is particularly preferred. According to the invention, it is possible to use a mixture of two, three or more of the aforementioned compounds as blocking agents.

In a preferred embodiment of the present invention, the majority of the isocyanate groups present in the polyisocyanate composition A are blocked. Most preferably at least 90% by weight, even more preferably at least 95% by weight and most preferably 98% by weight of the isocyanate groups present in the polyisocyanate composition A are blocked. The polyisocyanate composition A very particularly preferably does not contain any detectable free isocyanate groups. Free isocyanate groups can be determined by means of IR spectroscopy. The NCO band is observed ^{at 2700 cm 1.}

Silane-modified polyisocyanates

Silane modifications are used in coatings, for example to increase the hardness and / or the scratch resistance of the coating. If silane-modified isocyanates are used, both silane-functional groups and isocyanate groups are present in one molecule. The crosslinking of the silane groups with one another can be catalyzed, but it can also take place through post-curing, e.g. via air humidity. According to the invention, however, formulations with silane-functional isocyanates are designed in such a way that, after the first curing step, a coating is already present which can be demolded and which then reaches its final hardness through postcrosslinking.

In a preferred embodiment, the polyisocyanate composition A contains at least one silane-functional polyisocyanate, particularly preferably at least one silane-functional oligomeric polyisocyanate. These are compounds containing at least one silane group and at least one isocyanate group.

Silane-functional oligomeric polyisocyanates are usually obtained by oligomerizing simple aliphatic, cycloaliphatic, araliphatic and / or aromatic, monomeric diisocyanates, as described above as starting diisocyanates for the preparation of the oligomeric polyisocyanates, in a mixture with silicon-modified diisocyanates and / or isocyanatoalkysilanes or by partial conversion obtained oligomeric polyisocyanates with isocyanate-reactive silicon-containing compounds. The terms “partial reaction with silicon-containing compounds” or “silicon-modified” are used interchangeably in the context of the invention and mean in particular that 1 to 99.9 mol%, preferably 5 to 80 mol%, particularly preferably 10 to 50 mol%, very particularly preferably 15 to 40 mol%, of the isocyanate groups originally present in the oligomeric polyisocyanate or in the diisocyanate have been reacted with silicon-containing compounds. In other words, those produced by partial reaction of oligomeric polyisocyanates with silicon-containing compounds oligomeric, silane-functional polyisocyanates have an isocyanate content of 99.0 to 0.1 mol%, preferably 95 to 20 mol%, particularly preferably 90 to 50 mol%, very particularly preferably 85 to 60 mol%. based on the isocyanate groups originally present in the oligomeric polyisocyanates.

Production processes for the oligomeric, silane-functional polyisocyanates with uretdione, isocyanurate, allophanate, biuret, iminooxadiazinedione and / or oxadiazinetrione structure obtainable in the low-monomer composition A) according to the invention by reaction of oligomeric polyisocyanates with isocyanate-reactive silicon-containing compounds are for example in EP-A 1 273 640, WO-A 2008/074490, WO-A 2008/074489, WO-A 2014/086530, WO-A 2010/149236, WO-A 2009/156148.

Other oligomeric, silane-functional polyisocyanates are, for example, the polyisocyanates containing allophanate and silane groups, which are described in EP-A 2014692 and EP-A 2 305 691 and obtainable by reacting hydroxy urethanes or hydroxyamides containing silane groups with excess amounts of monomeric diisocyanates.

The use of the thioallophanates described in WO 2015/189164 in polyisocyanate composition A is also preferred, since, with a high content of silane groups, they also have a high average isocyanate functionality. These are compounds that are characterized by the general formula (I), in which R ¹ , R ² and R ³ 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 has up to 3 May contain heteroatoms from the series oxygen, sulfur, nitrogen,

X is a linear or branched organic radical with at least 2 carbon atoms, Y is a linear or branched, aliphatic or cycloaliphatic, an araliphatic or aromatic radical with up to 18 carbon atoms and n is an integer from 1 to 20.

The use of silane-functional polyisocyanates obtained by reacting the polyisocyanates mentioned earlier in this application as constituents of the polyisocyanate composition with silane-functional compounds, preferably silane-functional amines, aspartates, amides and thiols, is also preferred. Preferred silane-functional amines are selected from the group consisting of compounds according to formula (II), (III) and (IV). in which R ⁵ , R ⁶ and R ⁷ 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 has up to 3 May contain heteroatoms from the series oxygen, sulfur, nitrogen,

X stands for a linear or branched organic radical having at least 2 carbon atoms, which can optionally contain up to 2 imino groups (-NH-), and

R ^{8 represents} 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 stands in which R ⁵ , R ⁶ , R ⁷ and X have the meaning given above. Suitable aminosilanes of the general formula (II) are, for example, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-aminopropylethyldiethoxysilane, 3-aminopropyldimethoxysilane, 3-aminopropyldimethylethoxysilane, 3-aminopropyldimethylethoxysilane, 3-aminopropyldimethylethoxysilane, 3-aminopropyldimethylethoxysilane, 3-aminopropyldimethylethoxysilane, 3-aminopropyldimethylethoxysilane, 3-aminopropyldimethyl-propysilane, 3-aminopropyltripysilane, 3- aminopropyltriethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltripysilane, 3-aminopropyl-tri Aminopropylphenyldiethoxysilane, 3-aminopropylphenyldimethoxysilane, 3-aminopropyltris (methoxyethoxyethoxy) silane, 2-aminoisopropyltrimethoxysilane, 4-aminobutyltrimethoxysilane, 4-aminobutyltriethoxysilane, 4-aminobutyltriethoxyldimethoxysilane, 4-aminobutylmietoxyldimethoxysilane, 4-aminobutylmieto-methyldimethoxysilane, 4-aminobutylmietobutyldimethoxysilane, 4-aminobutylmietoxyldimethoxysilane, 4-aminobutylmietobutyldimethoxysilane, 4-aminobutylmieto-methyldimethoxysilane, 4-aminobutylmietobethyldimethoxysilane, 4-aminobutylmietobutyldimethoxysilane, 4-aminobutylmietobutyldimethoxysilane, 4-aminobutylmiethoxyethoxy)

Aminobutyldimethylmethoxysilane, 4-aminobutylphenyldimethoxysilane, 4-aminobutylphenyldiethoxysilane, 4-amino (3-methylbutyl) methyldimethoxysilane, 4-amino (3-methylbutyl) methyldiethoxysilane, 4-amino (3-methyl-aminopropyl-silane), 4-amino (3-methyl-aminopropyl-silane) propoxysilane, 3-aminopropylmethyldibutoxysilane, 3-aminopropyldiethylmethylsilane, 3-aminopropylmethylbis (trimethylsiloxy) silane, 11-aminoundecyltrimethoxysilane, N-methyl-3- aminopropyltrimethoxysilane, N-methyl-3-aminysilane, N-methyl-3-aminopropyltriethox- aminopropyltrimethoxysilane, N- (n-butyl) -3-aminopropyltriethoxysilane, N- (2-aminoethyl) -3- aminopropyltrimethoxysilane, N- (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) -phenethyltr imethoxysilane, N-vinylbenzyl-N- (2-aminoethyl) -3-aminopropylpolysiloxane, N-vinylbenzyl-N (2-aminoethyl) -3-aminopropylpolysiloxane, 3-ureidopropyltriethoxysilane, 3- (m-aminophenoxy) propyltrimethoxysilane , m- and / or p-aminophenyltrimethoxysilane, 3- (3-aminopropoxy) -3,3-dimethyl-1-propenyltrimethoxysilane, 3-

Aminopropylmethylbis (trimethylsiloxy) silane, 3-aminopropyltris (trimethylsiloxy) silane, 3-aminopropylpentamethyldisiloxane or any mixture of such aminosilanes. in which R ⁵ , R ^s and R ^{7 have} the meaning given for formula (II),

X for a linear or branched organic radical with at least 2

Carbon atoms stands and R ⁹ and R ^{10 are} independently saturated or unsaturated, linear or branched, aliphatic or cycloaliphatic or aromatic organic radicals having 1 to 18 carbon atoms, which are substituted or unsubstituted and / or have heteroatoms in the chain. in which R ⁵ , R ^s and R ^{7 have} the meaning given for formula (II),

X for a linear or branched organic radical with at least 2

Carbon atoms and

R ^{11 represents} a saturated linear or branched, aliphatic or cycloaliphatic organic radical having 1 to 8 carbon atoms.

These aminosilanes of the general formula (IV) are the known silane-functional alkylamides, such as can be obtained, for example, by the processes disclosed in US Pat.

Suitable production processes for the above-mentioned amino-functional silanes are known to the person skilled in the art and are described, for example, in the European patent application with the application number 19184068.

Trimerization Catalyst B

The trimerization catalyst B contains at least one catalyst which effects the trimerization of isocyanate groups to give isocyanurates and / or to give iminooxadiazinediones.

Suitable catalysts for the process according to the invention are, for example, simple tertiary amines, such as, for example, triethylamine, tributylamine, N, N-dimethylaniline, N-ethylpiperidine or N, N'-dimethylpiperazine. Suitable catalysts are also the tertiary hydroxyalkylamines described in GB 2221465, such as triethanolamine, N-methyl-diethanolamine, dimethylethanolamine, N-isopropyldiethanolamine and 1- (2-hydroxyethyl) pyrrolidine, or those known from GB 2 222 161, from mixtures tertiary bicyclic amines, such as DBU, with simple low molecular weight aliphatic alcohols existing catalyst systems. A large number of different metal compounds are also suitable as trimerization catalysts for the process according to the invention. For example, the octoates and naphthenates of manganese, iron, cobalt, nickel, copper, zinc, zirconium, cerium or lead or their mixtures with acetates of lithium, sodium, potassium, calcium or barium, which are described as catalysts in DE-A 3240613, are suitable, the sodium and potassium salts known from DE-A 3 219608 of linear or branched alkanecarboxylic acids with up to 10 carbon atoms, such as propionic acid, butyric acid, valeric acid, caproic acid, heptanoic acid, caprylic acid, pelargonic acid, capric acid and undecylic acid, which from EP-A 0 100 129 known alkali or alkaline earth metal salts of aliphatic, cycloaliphatic or aromatic mono- and polycarboxylic acids having 2 to 20 carbon atoms, such as sodium or potassium benzoate, which are disclosed in GB-PS 1,391,066 and GB-PS 1,386,399 known alkali phenolates, such as sodium or potassium phenolate, the alkali and alkaline earth oxides, hydroxides, carbonates, alcoholates and phenolates known from GB 809809, alkali metal salts of enolis iable compounds and metal salts of weak aliphatic or cycloaliphatic carboxylic acids, such as sodium methoxide, sodium acetate, potassium acetate, sodium acetoacetic ester, lead 2-ethylhexanoate and lead naphthenate, those known from EP-A 0056 158 and EP-A 0 056 159, with crown ethers or polyether alcohols complexed basic alkali metal compounds such as complexed sodium or potassium carboxylates, the pyrrolidinone potassium salt known from EP-A 0 033 581, the mononuclear or polynuclear complex compound of titanium, zirconium and / or hafnium such as zirconium tetra known from application EP 13196508.9 -n-butylate, zirconium tetra-2-ethylhexanoate and zirconium tetra-2-ethylhexylate, and tin compounds of the type described in European Polymer Journal, Vol. 16, 147 - 148 (1979), such as dibutyltin dichloride, diphenyltin dichloride, triphenylstannanol, tributyltin acetate, tributyltin oxide Tin dioctoate, dibutyl (dimethoxy) stannane and tributyl tin imidazolate.

Further trimerization catalysts suitable for the process according to the invention are, for example, the quaternary ammonium hydroxides known from DE-A 1667309, EP-A 0013880 and EP-A 0047452, such as tetraethylammonium hydroxide, trimethylbenzylammonium hydroxide, N, N-dimethyl-N-dodecyl-N- (2 -hydroxyethyl) ammonium hydroxide, N- (2-hydroxyethyl) -N, N-dimethylN- (2,2'-dihydroxymethylbutyl) ammonium hydroxide and 1- (2-hydroxyethyl) -1, 4-diazabicyclo- [2.2.2 ] Octane hydroxide (monoadduct of ethylene oxide and water with 1,4-diazabicyclo [2.2.2] octane), the quaternary hydroxyalkylammonium hydroxides known from EP-A 37 65 or EP-A 10 589, such as N, N, N- Trimethyl-N- (2-hydroxyethyl) ammonium hydroxide, the trialkylhydroxylalkylammonium carboxylates known from DE-A 2631733, EP-A 0671426, EP-A 1 599 526 and US 4,789,705, such as N, N, N-trimethyl-N- 2-hydroxypropylammonium-p-tert-butylbenzoate and N, N, N-trimethyl-N-2-hydroxypropylammonium-2-ethylhexanoate, the quaternary benzy known from EP-A 1 229 016 lammonium carboxylates, such as N-benzyl-N, N-dimethyl-N-ethylammonium pivalate, N-benzyl-N, N-dimethyl-N-ethylammonium-2-ethylhexanoate, N-benzyl-N, N, N-tributylammonium-2- ethylhexanoate, N, N-dimethyl-N-ethyl-N- (4-methoxy-benzyl) ammonium-2-ethylhexanoate or N, N, N-tributyl-N- (4-methoxybenzyl) ammonium pivalate, which are known from WO 2005/087828 known tetrasubstituted ammonium a-hydroxycarboxylates, such as, for example, tetramethylammonium lactate, the quaternary ammonium or phosphonium fluorides known from EP-A 0 339 396, EP-A 0 379 914 and EP-A 0 443 167, such as, for example, N-methyl-N , N, N-trialkylammonium fluoride with C8-C10-alkyl radicals, N, N, N, N-tetra-n-butylammonium fluoride, N, N, N-trimethyl-N-benzylammonium fluoride,

Tetramethylphosphonium fluoride, tetraethylphosphonium fluoride or tetra-n-butylphosphonium fluoride, the quaternary ammonium and phosphonium polyfluorides known from EP-A 0798 299, EP-A 0896009 and EP-A 0962455, such as, for example, benzyltrimethylammonium hydrogen polyfluoride, those from EP-A-0 668 271 known

Tetraalkylammonium alkyl carbonates, which are obtainable by reacting tertiary amines with dialkyl carbonates, or betaine-structured quaternary ammonio alkyl carbonates, the quaternary ammonium hydrogen carbonates known from WO 1999/023128, such as choline bicarbonate, the esters known from EP 0 102482 from tertiary amines and alkylating esters Quaternary ammonium salts obtainable from acids of phosphorus, such as reaction products of triethylamine, DABCO or N-methylmorpholine with dimethyl methanephosphonate, or the tetrasubstituted ammonium salts of lactams known from WO 2013/167404, such as trioctylammonium caprolactamate or dodecylcaprolactamate or dodecyltrimethyl ester.

Further trimerization catalysts B suitable according to the invention can be found, for example, in J. H. Saunders and K. C. Frisch, Polyurethanes Chemistry and Technology, pp. 94 ff (1962) and the literature cited there.

Carboxylates and phenates with metal or ammonium ions as counterions are particularly preferred. Suitable carboxylates are the anions of all aliphatic or cycloaliphatic carboxylic acids, preferably those with mono- or polycarboxylic acids having 1 to 20 carbon atoms. Suitable metal ions are derived from alkali or alkaline earth metals, manganese, iron, cobalt, nickel, copper, zinc, zirconium, cerium, tin, titanium, hafnium or lead. Preferred alkali metals are lithium, sodium and potassium, particularly preferably sodium and potassium. Preferred alkaline earth metals are magnesium, calcium, strontium and barium.

The octoates and naphthenates of manganese, iron, cobalt, nickel, copper, zinc, zirconium, cerium or lead or mixtures thereof with acetates of lithium, sodium, potassium, calcium are very particularly preferred or barium.

Also very particularly preferred are sodium or potassium benzoate, the alkali metal phenolates known from GB-PS 1,391,066 and GB-PS 1,386,399, such as. B. sodium or potassium phenolate, as well as the alkali and alkaline earth oxides, hydroxides, carbonates, alcoholates and phenolates known from GB 809 809. If the trimerization catalyst B is poorly or not soluble in the polyisocyanate composition A, its effect can be made possible or enhanced by adding a solubilizer. Trimerization catalysts B based on alkali and alkaline earth oxides, hydroxides, carbonates or alcoholates preferably contain a polyether. This is particularly preferred when the catalyst contains metal ions. Preferred polyethers are selected from the group consisting of crown ethers, diethylene glycol, polyethylene and polypropylene glycols. In the process according to the invention, it has proven to be particularly practical to use a trimerization catalyst B which contains, as polyether, a polyethylene glycol or a crown ether, particularly preferably 18-crown-6 or 15-crown-5. The trimerization catalyst B preferably contains a polyethylene glycol with a number average molecular weight of 100 to 1000 g / mol, preferably 300 g / mol to 500 g / mol and in particular 350 g / mol to 450 g / mol.

The combination of the above-described carboxylates and phenolates of alkali or alkaline earth metals with a polyether is very particularly preferred.

Furthermore, the trimerization catalysts described in EP 3 337 836 and WO2015 / 124504 are particularly well suited for the use according to the invention.

Isocyanate-reactive compound C

In a preferred embodiment, the reaction mixture contains at least one isocyanate-reactive compound C. An “isocyanate-reactive compound” is a compound which carries at least one isocyanate-reactive group as defined above in this application suggest that the stoichiometric ratio of isocyanate groups to isocyanate-reactive groups according to the claims is maintained in the reaction mixture. Isocyanate-reactive compounds C are preferably used as solvents for the trimerization catalyst B and / or as a flexibilizing component. A "flexibilizing component" lowers the Tg of a coating compared to a coating obtained from the same reaction mixture without adding the flexibilizing component.

In principle, monohydric or polyhydric alcohols, amino alcohols, amines and thiols are suitable as isocyanate-reactive compound C. The aforementioned compounds preferably have an average functionality of at least 2 isocyanate-reactive groups per molecule.

Preferred amines are organic di- or polyamines, preferably selected from the group consisting of 1,2-ethylenediamine, 1,2- and 1,3-diaminopropane, 1,4-diaminobutane, 1,6-diaminohexane, isophoronediamine, the isomer mixture of 2 , 2,4- and 2,4,4-trimethylhexamethylenediamine, 2-methylpentamethylenediamine, diethylenetriamine, 4,4-diaminodicyclohexamethane, hydrazine hydrate, Dimethylethylenediamine, polyethers modified with amino end groups and compounds according to formula (V) are used. The aforementioned compounds are preferably used as a flexibilizing component.

Here stands

X stands for an n-valent radical which is inert towards isocyanate groups, as it is by

Removal of the primary amino groups from an organic amine of molecular weight range 60 to 6000 with n primary aliphatically and / or cycloaliphatically bound amino groups is obtained, which optionally one or more heteroatoms and / or other isocyanate-reactive and / or inert at temperatures up to 100 ° C contains functional groups,

R ¹ and R ² for identical or different organic radicals with 1 to 18 carbon atoms and n for an integer> 1.

Amines which contain at least one amino group and at least one hydroxyl group (amino alcohols) are likewise preferred. Such compounds are preferably selected from the group consisting of diethanolamine, 3-amino-1-methylaminopropane, 3-amino-1-ethylaminopropane, 3-amino-1-cyclohexyl-aminopropane, 3-amino-1-methylaminobutane,

Alkanolamines such as N-aminoethylethanolamine, ethanolamine, 3-aminopropanol and neopentanolamine. The aforementioned compounds are preferably used as a flexibilizing component.

In principle, all known monomeric and polymeric polyols can be used individually or as a mixture as a flexibilizing component. These are in particular the usual polyester polyols, polyether polyols, polyacrylate polyols and polycarbonate polyols known from polyurethane chemistry.

Suitable polyester polyols are preferably those having an average molecular weight, which can be calculated from functionality and hydroxyl number, of 200 g / mol to 3000 g / mol, preferably of 250 to 2500, with a hydroxyl group content of 1 to 21% by weight, preferably 2 to 18% by weight, as they are in a manner known per se by reacting polyhydric alcohols with insufficient amounts of polybasic carboxylic acids Let carboxylic acid anhydrides, corresponding polycarboxylic acid esters of lower alcohols or lactones be produced. Suitable polyether polyols are preferably those with an average molecular weight, which can be calculated from functionality and hydroxyl number, of 200 g / mol to 6000 g / mol, preferably 250 g / mol to 4000 g / mol with a hydroxyl group content of 0.6 to 34 wt. %, preferably 1 to 27% by weight, as can be obtained in a manner known per se by alkoxylation of suitable starter molecules. Any polyhydric alcohols, for example those in the molecular weight range 62 g / mol to 400 g / mol, can be used to produce these polyether polyols.

Suitable polyacrylate polyols are, for example, those having an average molecular weight, which can be calculated from functionality and hydroxyl number or can be determined by gel permeation chromatography (GPC), of 800 to 50,000, preferably 1000 to 20,000, with a hydroxyl group content of 0.1 to 12% by weight, preferably 1 to 10, how they can be produced in a manner known per se by copolymerization of olefinically unsaturated monomers containing hydroxyl groups with olefinic monomers free of hydroxyl groups.

Examples of suitable monomers for producing the polyacrylate polyols are vinyl or vinylidene monomers such as styrene, α-methylstyrene, o- or p-chlorostyrene, o-, m- or p-methylstyrene, p-tert-butylstyrene, acrylic acid, acrylonitrile , Methacrylonitrile, acrylic and methacrylic acid esters of alcohols with up to 18 carbon atoms, such as. B. methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, amyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, 3,3,5-trimethylhexyl acrylate, stearyl acrylate, cyclohexyl acrylate, cyclopentyl acrylate, cyclohexyl acrylate, cyclopentyl acrylate tert-Butycyclohexylacrylat, isobornyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, amyl methacrylate, hexyl methacrylate, 2-ethylhexyl, isooctyl, 3,3,5-Trimethylhexylmethacrylat, stearyl methacrylate, lauryl methacrylate, cyclopentyl methacrylate, cyclohexyl methacrylate , 4-tert-butycyclohexyl methacrylate, norbornyl methacrylate or isobornyl methacrylate, diesters of fumaric acid, itaconic acid or maleic acid with alcohols containing 4 to 8 carbon atoms, acrylic acid amide, methacrylic acid amide, vinyl esters of alkane monocarboxylic acids with 2 to 5 carbon atoms, such as. B. vinyl acetate or vinyl propionate, hydroxyalkyl esters of acrylic acid or methacrylic acid with 2 to 5 carbon atoms in the hydroxyalkyl radical, such as. B. 2-hydroxyethyl, 2-hydroxypropyl, 3-hydroxypropyl, 3-hydroxybutyl, 4-hydroxybutyl, trimethylolpropane mono- or pentaerythritol monoacrylate or methacrylate, and any mixtures of such exemplified monomers. In particular, the compounds mentioned above as solvents for the trimerization catalyst B are also suitable for use as flexibilizing components. These connections can thus fulfill a double function.

Particularly preferred isocyanate-reactive compounds are those compounds which do not contribute to a substantial increase in the viscosity of the reaction mixture as defined above, but allow the reaction mixture to be processed at the injection temperature within the viscosity limits defined above.

Additive D

The reaction mixture preferably contains at least one additive D selected from the group consisting of stabilizers also against UV light, antioxidants, water scavengers, leveling agents, rheology additives, slip additives, defoamers, wetting and dispersing agents, adhesion promoters, corrosion inhibitors, flame retardants, nanoparticles, fillers also in the form of inorganic or organic fibers, dyes and pigments.

Suitable UV stabilizers can preferably be selected from the group consisting of piperidine derivatives, such as 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, 4-benzoyloxy-1,2,2,6,6-pentamethylpiperidine, bis- ( 2,2,6,6-tetra-methyl-4-piperidyl) sebacate, bis (1,2,2,6, 6-pentamethyl-l-4-piperidinyl) sebacate, bis- (2,2,6 , 6-tetramethyl-4-piperidyl) suberate, bis (2,2,6,6-tetramethyl-4-piperidyl) dodecanedioate; Benzophenone derivatives, such as, for example, 2,4-dihydroxy-, 2-hydroxy-4-methoxy-, 2-hydroxy-4-octoxy-, 2-hydroxy-4-dodecyloxy- or 2,2'-dihydroxy-4-dodecyloxy-benzophenone ; Benzotriazole derivatives such as 2- (2H-benzotriazol-2-yl) -4,6-di-tert-pentylphenol, 2- (2H-benzotriazol-2-yl) -6-dodecyl-4-methylphenol, 2- (2H -Benzotriazol-2-yl) -4,6-bis (l-methyl-l-phenylethyl) phenol, 2- (5- chloro-2H-benzotriazol-2-yl) -6- (l, l-dimethylethyl) - 4-methylphenol, 2- (2H-benzotriazol-2-yl) -4-

(l, l, 3,3-tetramethylbutyl) phenol, 2- (2H-benzotriazol-2-yl) -6- (l-methyl-l-phenylethyl) -4- (l, 1,3,3-tetramethylbutyl) phenol, isooctyl-3- (3- (2H-benzotriazol-2-yl) -5- (l, l-dimethylethyl) -4- hydroxyphenylpropionate), 2- (2H-benzotriazol-2-yl) -4,6- bis (l, l-dimethylethyl) phenol, 2- (2H-benzotriazol-2-yl) -4,6-bis (l-methyl-l-phenylethyl) phenol, 2- (5-chloro-2H-benzotriazol-2 -yl) -4,6- bis (l, l-dimethylethyl) phenol; Oxalanilides such as 2-ethyl-2'-ethoxy- or 4-methyl-4'-methoxyoxalanilide; Salicylic acid esters such as phenyl salicylate, 4-tert-butylphenyl salicylate, 4-tert-octylphenyl salicylate; Cinnamic acid ester derivatives, such as methyl a-cyano-β-methyl-4-methoxycinnamate, butyl a-cyano-β-methyl-4-methoxycinnamate, ethyl a-cyano-β-phenylcinnamate, isooctyl α-cyano-β-phenylcinnamate; and

Malonic ester derivatives, such as, for example, 4-methoxy-benzylidene-malonic acid dimethyl ester, 4-methoxy-benzylidene-malonic acid diethyl ester, 4-butoxy-benzylidene-malonic acid dimethyl ester. These preferred UV stabilizers can be used either individually or in any combination with one another. Optionally, one or more of the exemplified UV stabilizers of the coating compositions according to the invention are preferably used in amounts of 0.001 to 3.0% by weight, particularly preferably 0.01 to 2% by weight, calculated as the total amount of UV stabilizers used, based on the total amount of polyisocyanate component A added. Combinations of UV absorbers and radical scavengers are preferred, in particular those radical scavengers which belong to the group of sterically hindered light stabilizers (“HALS”).

Suitable antioxidants are preferably sterically hindered phenols, which can preferably be selected from the group consisting of 2,6-di-tert-butyl-4-methylphenol (ionol), pentaerythritol tetrakis (3- (3,5-di-tert butyl-4-hydroxyphenyl) propionate), octadecyl 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, triethylene glycol bis (3-tert-butyl-4-hydroxy -5-methylphenyl) propionate, 2,2'-thio-bis (4-methyl-6-tert-butylphenol) and 2,2'-thiodiethyl-bis [3- (3,5-di-tert-butyl-4 hydroxyphenyl) propionate]. If required, these can be used individually or in any combination with one another.

These antioxidants are preferably used in amounts of 0.01 to 3.0% by weight, particularly preferably 0.02 to 2.0% by weight, calculated as the total amount of antioxidants used based on the total amount of polyol component A.

In order to prevent premature crosslinking of the alkoxysilyl groups when using polyisocyanates containing alkoxysilyl groups, the addition of water scavengers, for example orthoformic acid esters, such as. B. triethyl orthoformate, or vinylsilanes, such as. B. vinyltrimethoxysilane, be advantageous. These water scavengers come, if at all, in amounts from 0.01% by weight to 5% by weight, preferably from 0.01% by weight to 2% by weight, based on the total amount of the polyisocyanate component A used.

To improve the wetting of the substrate, the reaction mixtures according to the invention can optionally contain suitable leveling agents, for example organically modified siloxanes, such as. B. polyether-modified siloxanes, polyacrylates and / or fluorosurfactants contain. These leveling agents come, if at all, in amounts from 0.01% by weight to 3% by weight, preferably from 0.01% by weight to 2% by weight, particularly preferably from 0.05 to 1% by weight , 5% by weight, based on the total amount of the reaction mixture used.

To optimize the flow behavior, the reaction mixture can contain rheology additives, for example colloidal silicas, very finely divided bentonites, microcrystalline polyethylene waxes, polyamide dispersions and / or crystalline ureas.

The slip additives, defoamers, fillers and / or pigments also optionally contained in the coating compositions according to the invention as further auxiliaries and additives are the Known to those skilled in the art and, if at all, are used in the amounts customary in paint technology. A detailed overview of such suitable auxiliaries and additives can be found, for example, in Bodo Müller, "Additive Kompakt", Vincentz Network GmbH & Co KG (2009).

Preparation of the reaction mixture according to the invention

The components of the reaction mixture according to the invention are mixed immediately before the cavity is filled in the Reaction Injection Molding (RIM) process using automated metering and mixing devices. It is preferred that the reaction mixture is provided in two or three components in suitable storage vessels and is dosed automatically from the storage vessels. The individual components are preferably temperature-controlled differently or all in the same way in such a way that the desired injection temperature of the mixture can be easily achieved. Depending on the desired injection method, the components can already be made available in the storage vessels under increased pressure.

If coatings of the same type are always to be produced in one apparatus using the RIM process, a two-component provision is preferred. Polyisocyanate mixture A and trimerization catalyst B are then preferably provided in different storage vessels. In this case, the additive component D and, if present, the optional isocyanate-reactive compound C are preferably also added to component B. In this embodiment, the reaction mixture only arises while the components are being injected into the shaping tool.

If, on the other hand, frequently changing coatings, for example coatings with different colors or effects, are to be produced in the RIM process, a three-component provision is preferred. Again, polyisocyanate mixture A and trimerization catalyst B are preferably provided in different storage vessels. At least part of the additive component D and optionally part of the optional isocyanate-reactive compound C is provided as a third component in further storage vessels. The third component can then be present in different forms, for example colors and / or effects, in different storage vessels, which can be processed with a 3K RIM system known per se in a rapid change in color and / or effect. Parts of components D and C can also be added to the component which contains the trimerization catalyst B.

In a particularly preferred embodiment, the third component contains a coloring and / or effect pigment paste which contains at least one polyester or polyether polyol (mentioned under C) and at least one dispersing aid (named under D).

The production of the individual components takes place according to the usual methods of coating technology for two- or multi-component polyurethane paints, for example Mixing in stirring vessels or, if solids such as pigments are present, in dispersing systems such as dissolvers or grinding units such as bead mills.

Coating of workpieces by reaction injection molding

When using the reaction mixture for coating workpieces by reaction injection molding, the workpiece, which serves as a carrier for the coating to be built up, is introduced into a shaping tool which at least partially encloses the workpiece. It is preferred that the shaping tool can be heated, because in this way the curing of the reaction mixture can be brought about by simply heating the tool. The inside of the shaping tool, which faces the workpiece and comes into contact with the reaction mixture, can be structured in order to create a structure on the surface of the coating to be built up.

The workpiece contains at least one material selected from the group consisting of plastics, composites such as fiber-reinforced plastics, electronic components, wood, natural stone and metal. It preferably consists of at least 90% by weight of one or more of the aforementioned materials. Preferred plastics are selected from the group consisting of ABS, AMMA, ASA, CA, CAB, COC, EP, UF, CF, MF, MP, PF, PAN, PA, PBS, PC, PE, PE-HD, PE-LD , PE-LLD, PE-UHMW, PPS, PET, PEEK, PLA, PMMA, PP, PS, PPS, SB, PUR, PVC, SAN, PBT, PPE, POM, PP / EDP, UP (abbreviations according to DIN EN ISO 1043-1: 2016), polyoxazolidinones, thermoplastic polyurethane, melamine-phenol-formaldehyde, and mixtures thereof. Both homopolymers and copolymers of the abovementioned plastics or their mixtures are suitable. Preferred mixtures are PC + ABS, PC + PBT and PC + PET. It is particularly preferred that the workpiece to be coated consists of at least 90% by weight of a thermoplastic polymer. The workpiece can optionally be pretreated. Examples of pretreated workpieces are workpieces provided with adhesion promoters, metallized workpieces, printed workpieces, workpieces coated with decorative foils, labeled workpieces, stained, colored and / or wooden workpieces treated with primers.

A workpiece to be coated does not necessarily consist of a single component. In a preferred embodiment of the present invention, there is at least one further component on the surface of the component to be coated, which is then likewise at least partially enclosed by the shaping tool. This further component is preferably selected from the group consisting of sensors, lighting elements and actuators.

It is further preferred that the workpiece to be coated contains cutouts of any geometry. This is shown schematically in Figure 1. The workpiece (hatched diagonally) contains a recess (gray). When such a recess is enclosed by the shaping tool together with the parts of the workpiece to be coated that surround it and coated, a coating is created that covers the recess (black) and covers at least part of the workpiece. After the coating, a further component (hatched horizontally) can then be inserted into the recess and, together with the workpiece, is covered by a uniform and undamaged coating. Preferred components are selected from the group consisting of sensors, lighting elements and actuators.

A cavity remains between the inside of the shaping tool and the surface of the workpiece enclosed by the shaping tool. The reaction mixture is then introduced into the cavity. The complete mixing of all components of the reaction mixture can take place before the introduction, but it can also take place e.g. by means of suitable mixing units during the introduction. For mixing and introducing the reaction mixture, preference is given to using RIM systems such as those commercially available from Isotherm AG, Uetendorf, CH, for example under the name PSM 90 or PSM 3000, from the KraussMaffei Group, DE under the process / technology name ColorForm and from Hennecke GmbH, Sankt Augustin, DE under the process / technology name ClearRIM. The KrausMaffei Group, DE, also offers optional color modules for the ColorForm system that can work with three components and thus allow, for example, a quick color change.

The distance between the inside of the shaping tool and the surface of the workpiece to be coated is preferably between 50 μm and 5 mm. This distance is preferably determined along the normal to the surface of the workpiece.

The coating preferably has an extension of at least 10 mm along at least one axis of a two-dimensional Cartesian coordinate system.

The cavity is preferably filled with the reaction mixture under a pressure that is higher than the ambient pressure. During the curing process, the pressure in the cavity preferably also remains higher than the ambient pressure.

When the cavity is completely filled with the reaction mixture, it is cured by the elevated temperature applied there until the coated workpiece can be removed from the mold. The inside of the shaping tool preferably has a temperature between 60 ° C and 300 ° C. The coated workpiece can then be removed from the shaping tool. The above-mentioned upper limit of the temperature during curing is of course dependent on the nature of the workpiece to be coated. If this is damaged at a given temperature, the temperature during curing must be below this value. For workpieces that are made of or contain thermoplastic polymers the upper limit is preferably 130 ° C, more preferably 100 ° C. In order to ensure sufficiently rapid curing, a preferred lower temperature limit is 80 ° C.

According to the invention, it is thus possible to build up a coating using an automated method. Since the curing of the reaction mixture takes place through the reaction of isocyanate groups with one another, the isocyanate groups according to the invention being in significant excess, and not primarily through the reaction of two different functional groups, the reaction mixture is less prone to mixing errors than two-component systems. A mechanical or chemical pretreatment of the tool to be coated is usually unnecessary. Even workpieces with more complex geometry, where a coating can only be applied with difficulty using conventional methods, can be coated in this way. Since the coating composition is cured, inter alia, through the formation of isocyanurate groups, the coatings obtained in this way have high mechanical and chemical resistance. If the polyisocyanate composition A contains only small amounts or no proportions of aromatic isocyanates, coatings that are very weather-resistant can be obtained.

In a further embodiment, the present invention relates to a method for coating a workpiece comprising the steps of a) introducing a workpiece into a shaping tool which encloses at least part of the workpiece and which is dimensioned such that the distance between the surface of the workpiece and the The inside of the forming tool corresponds to the thickness of the coating; b) Filling in at least one reaction mixture with a molar ratio of isocyanate groups to isocyanate-reactive groups of at least 3: 1

(i) at least one polyisocyanate composition A, and

(ii) at least one trimerization catalyst B into the cavity between the workpiece and the shaping tool; and c) curing of the reaction mixture filled in process step b) at a temperature between 60 ° C. and 300 ° C., with at least 30 mol% of the free isocyanate groups present at the beginning of process step c) being converted to isocyanurate groups. All of the definitions given above for the reaction mixture and its components and the use also apply to this embodiment.

The workpiece can be introduced into the shaping tool in any manner known to a person skilled in the art of reaction injection molding. A cavity is located at at least one point between the surface of the workpiece to be coated and the inside of the shaping tool. This serves to take up the reaction mixture in process step b). Its thickness, i.e. the distance between the surface of the workpiece and the inside of the forming tool, determines the layer thickness of the resulting coating. The structure of the surface of the resulting coating can be determined by the design of the inside of the shaping tool. The shaping tool encloses at least part of the workpiece in such a way that the cavity is sealed off from the outside and the reaction mixture filled in by valves or other suitable devices cannot run out of the cavity.

In process step b), at least one reaction mixture is poured into the cavity. This can be done in any of the ways known to a person skilled in the art in the field of reaction injection molding. Depending on the reactivity of the reaction mixture used, the reaction mixture can be pre-mixed in a storage container. This is preferred for reaction mixtures which have a low reactivity at room temperature.

If the reactivity is too high at room temperature, the polyisocyanate A and the trimerization catalyst B are, however, preferably stored in separate containers and only mixed during the filling. Suitable valves, nozzles and mixing heads are well known to the person skilled in the art in the field of two-component polyurethane systems.

Compared to the aforementioned two-component polyurethane system, the process according to the invention is less prone to mixing errors: Variations in the stoichiometry of catalyst and isocyanate influence the rate of curing, but not the properties of the finished coating. In contrast, variations in the stoichiometric ratio of NCO groups and OFI groups in the known polyurethane systems inevitably lead to materials with changed properties.

When the cavity has been completely filled in process step b), the temperature of the reaction mixture is raised to at least 60 ° C. in process step. The selection of the suitable temperature depends on the one hand on the sensitivity of the workpiece to be coated. The hardening temperature must not reach a level that would damage the workpiece. Within this range, however, the choice of higher temperatures is generally preferred in order to achieve rapid curing and the associated short cycle times. An absolute upper limit For the curing temperature in the process according to the invention, the material formed from the reaction mixture itself sets: Polyisocyanurate plastics decompose at temperatures above 300 ° C, so that this value is only exceeded for a maximum of 5 seconds, but preferably not at all, during process step c). Particularly suitable temperature ranges are disclosed further above in this application.

Process step c) is carried out until the coated workpiece can be removed from the mold. The term "demouldable" denotes a state of the workpiece in which it can be removed from the shaping tool without residues of the reaction mixture sticking to the inside of the shaping tool. In this case, it is not necessary that all of the isocyanate groups have already reacted it is preferred that at the end of process step c) between 15 and 85%, more preferably between 30 and 75% and particularly preferably 40 to 75% of the isocyanate groups present at the beginning of process step c) have reacted. mirror image between 5 and 85%, more preferably between 25 and 70% and particularly preferably 25 to 60% of the isocyanate groups originally present.

In a preferred embodiment of the present invention, at least 40 mol%, preferably at least 50 mol% and most preferably at least 50 mol% of the free isocyanate groups present at the beginning of process step c) are converted to isocyanurate groups. The result is a coating, the crosslinking of which is largely mediated via isocyanurate groups. Such coatings are distinguished by their superior resistance to chemical and physical influences.

The crosslinking of the free isocyanate groups still present after the end of process step c) takes place outside the molding tool and preferably at temperatures between 10 and 120.degree. Therefore, in a preferred embodiment of the present invention, the process according to the invention contains a process step following process step c), in which the free isocyanate groups still present at the end of process step c) at a temperature between 10 and 120 ° C, preferably between 10 and 40 ° C, are further networked outside of the shaping tool. This process step is preferably carried out until at least 95% of the isocyanate groups present at the beginning of process step c) have reacted.

Process step c) is preferably carried out for 10 seconds to 900 seconds, more preferably for 10 seconds to 180 seconds and even more preferably for 10 seconds to 90 seconds. “Implementation” in this context means that the reaction mixture as a whole is in contact with the inside of the shaping tool for this period and said inside has a temperature between 60 ° C and 300 ° C. At the end of process step c) the coating preferably has a Tg of 40 ° C to 300 ° C, more preferably 60 ° C to 180 ° C.

In a preferred embodiment of the present invention, the workpiece consists of at least 90% by weight of a thermoplastic synthetic material and process step a) is preceded by a process step of manufacturing said workpiece by injection molding. Between the process step of producing the workpiece consisting of a thermoplastic polymer by injection molding and the beginning of process step a), preferably a maximum of 5 minutes, preferably a maximum of 30 seconds, elapse.

In a further embodiment, the present invention relates to a coating obtained or obtainable by the above-defined process according to the invention.

This coating according to the invention is particularly preferred in infrared spectrometric analysis due to a ratio of the absolute peak heights of the CH2 band and the NH-d band of at least 0.85: 1 with a simultaneous ratio of the absolute peak heights of the isocyanurate band and the NH-d band of marked at least 5.5: 1. The greatest absolute intensity was determined for each band. For CH2 the measurements were between 2900 and 3000 cm ¹ , for NH-d between 1480 and 1600 cm ¹ and for isocyanurate between 1590 and 1700 cm ¹ . These properties exist when at least 95% of the isocyanate groups originally present in the reaction mixture at the beginning of process step c) have reacted. This point in time should be reached immediately after process step c), in particular if it is carried out for a long time at high temperatures. As a rule, however, the aforementioned degree of conversion is achieved through a combination of curing in the process step and post-curing outside of the shaping tool in the case of the method defined for this purpose further in this application. If the aforementioned conditions are observed, the Tg of the coating is 40 ° C. to 300 ° C., preferably 60 ° C. to 180 ° C.

In a preferred embodiment, the coating is free of pigments and has a Hazen color number of at most 50, preferably at most 30. Hazen color numbers are preferably determined using a micro-haze plus device from Byk-Gardner GmbH, Geretsried, Germany, at an angle of 20 °.

The coating preferably has a density of at least 0.95 g / cm ³ .

In yet another embodiment, the present invention relates to a workpiece coated with the coating defined above.

Such workpieces are preferably electrical devices, furniture, toys or wooden or plastic components for automobiles or airplanes. Figure 1A shows a workpiece (hatched diagonally) with a recess (gray) in plan view. Figure 1B shows a cross-section of the workpiece with the recess.

Figure IC shows the cross-section of the workpiece after coating. The workpiece and recess are now covered by the coating (black).

Figure ID shows a coated workpiece in which a component (hatched horizontally) was inserted into the original recess.

The following exemplary embodiments only serve to illustrate the invention. They are not intended to limit the scope of protection of the claims in any way.

Working examples

The tests were carried out on a Battenfeld HM 370/1330 injection molding machine, combined with a laboratory piston dosing system for 2 components. The tool used was a DIN-A5 plate tool, which was coated with a mass of approx. 41 g of paint, which corresponds to a paint layer thickness of 280 μm to 390 μm.

The following materials were used:

Desmophen XP 2488, branched polyester polyol, available from Covestro Deutschland AG, with the following properties:

Desmophen C1100, linear, aliphatic polycarbonate polyester, available from Covestro Deutschland AG, with the following properties:

Polyisocyanate B1

The HDI polyisocyanate B1 containing isocyanurate groups was prepared according to EP-A 330 966, Example 11, using 2-ethylhexanol instead of 2-ethyl-1,3-hexanediol as the catalyst solvent. After the excess monomeric HDI had been separated off by means of thin-layer distillation, an HDI polyisocyanate with an NCO content of 22.9%, a viscosity of 1200 mPas at 23 ° C. and an average NCO functionality of 3.1 (calculated from the NCO content and number average molecular weight, determined by GPC measurement). Makrolon 2405/901510, black polycarbonate

The catalyst was prepared according to EP 333 7836, Example 1a.

The following materials were used for the paint:

Component A

Desmophen C1100 20.6 g

Desmophen XP 2488 8.8 g

Catalyst 3.0 g

The polyols Desmophen C1100 and Desmophen XP 2488 were used in a mass ratio of 70:30. The amount of catalyst used corresponds to a concentration of 2.91% by weight based on the total mass (component A + component B), calculated for degree of crosslinking 3.

Component B: polyisocyanate B1, for amount see table 1.

Both components were heated to approx. 90 ° C before the experiment. The surface temperature of the tool was 117 ° C. The thermoplastic was melted in the extruder at 290 ° C and injected into the tool at a mold temperature set at 120 ° C. The experimental release agent L9500021 from Votteler was applied manually to the plate tool, with any external release agent generally being suitable for polyurethane systems.

Various degrees of crosslinking were used to coat the test panels. The degree of crosslinking was calculated based on the theoretical isocyanate and OH contents:

Degree of crosslinking 1 = ratio of NCO groups to OH groups of 1: 1 Degree of crosslinking 3 = ratio of NCO groups to OH groups of 3: 1

The following parameters were used for the coating tests:

Table 1: Overview of the mixing ratios of polyol (A) to isocyanate (B) used and the degrees of crosslinking achieved with them, as well as the parameters set

At least 6 parts of each degree of crosslinking were made.

For each degree of crosslinking, the residual NCO content of at least one component was determined by means of IR after the following times. To this end, an unreacted mixture of components A and B, mixed at room temperature, was measured according to the degree of crosslinking and the peak contained therein for the NCO group at approx. 2200 cm ¹ was normalized to 100%. The measurements were made on the infrared spectrometer, Bruker Tensor II, using a Platinum ATR unit. The spectrometer was controlled with the device software OPUS Version 7.5, which was also used for the evaluation. After baseline correction (rubber band method) and normalization to CH ₂ / CH ₃ (min. -Max. Normalization in the range 2800-3000 cm ¹ ), a straight line between 2380 cm ¹ and 2170 cm ¹ was calculated for the area integration and the area above it was calculated.

Table 2: Overview of the percentage content of residual NCO in the components with different degrees of crosslinking, measured after different time intervals. If the average value was below 5%, the development was not followed up.

In addition, the ratios of the absolute peak heights of different signals were compared, the greatest absolute intensity of the band being determined in each case. The measurements for CH _{2 were} between 2900 and 3000 cm ¹ , for NH-d between 1480 and 1600 cm ¹ and for isocyanurate between 1590 and 1700 cm ¹ . The peak heights were correspondingly related to the other signal. Only fully cured components were used for this investigation, ie the measurements took place approx. 6 months after the Fier position. Table 3 shows an overview. Table 3: Overview of the ratios of the peak heights of CH2 to NH-d and isocyanurate to NH-d for different degrees of crosslinking.

The following paint tests were carried out on the paints:

Hazen color numbers were determined with a micro-haze plus device from Byk-Gardner GmbHFI, Geretsried, Germany, at an angle of 20 °.

The gloss of the coatings obtained was measured reflectometrically in accordance with DIN EN ISO 2813: 2014 at a 20 ° angle.

Glass transition temperature (TG) by means of differential scanning calorimetry (DSC) The measurements were carried out with a DSC 8500 calorimeter from Perkin Elmer. The calibration of the temperature was carried out on indium and lead (enamel onset), that of the heat tone on indium (enamel surface integral). Three heatings from -65 ° C to +150 ° C with a heating rate of 20 K / min were carried out. Between the heatings, cooling was carried out at a cooling rate of 320 K / min. The measurements were carried out under nitrogen, a closed aluminum crucible for solids was used as the sample container.

Solvent resistance

A small amount of the appropriate solvent (xylene, 1-methoxy-2-propyl acetate (MPA), ethyl acetate or acetone) was placed in a test tube, which was fitted with a cotton swab at the opening so that a solvent-saturated atmosphere inside the test tube originated. The test tubes were then placed on the paint surface with the cotton ball and remained there for 5 minutes. After wiping off the solvent, the film was tested for destruction / softening / loss of adhesion and assessed visually from 0 (no change) to 5 (paint surface destroyed).

Pendulum damping was measured in accordance with DIN EN ISO 1522 (edition 2007-04-01) according to Koenig, the sample plates being described in accordance with DIN 1514.

Cross-cut adhesion tests were carried out in accordance with DIN EN ISO 2409 (edition 2019-09-01), with a spacing of the grid lines of 3 mm. Sunscreen resistance was determined based on the Ford test / USA PV 3964 (Engineering Material Specification / Soiling and Cleanability FLTM BN 112-08, ISO 105-A02 / AATCC). The sun cream was applied to the paint surface to be tested and then stored at 70 ° C. for 4 hours. The test surfaces were wiped with a cosmetic tissue immediately after exposure. After wiping off the sun cream, the film was tested for destruction / softening / flaft loss and assessed visually from 0 (no change) to 5 (paint surface destroyed).

Table 4: Overview of the test results on direct coating components with various degrees of crosslinking. The tests were carried out in accordance with the descriptions above.

The evaluation of the data listed in Table 4 shows that a higher degree of crosslinking is correlated with a higher glass transition temperature TG and a higher pendulum damping. In addition, it can be seen that the properties of the paint surfaces with regard to resistance to sunscreen and solvents improve with increasing degree of crosslinking. The jump in properties is particularly evident from a degree of crosslinking of 3.

Claims

1. Use of a reaction mixture with a molar ratio of isocyanate groups to isocyanate-reactive groups of at least 3: 1 for coating workpieces by reaction injection molding, the reaction mixture containing a) at least one polyisocyanate composition A, and b) at least one trimerization catalyst B and at least 30 mol -% of the free isocyanate groups present in the reaction mixture are converted to isocyanurate groups.

2. The use of the reaction mixture according to claim 1, wherein the reaction mixture additionally contains at least one isocyanate-reactive compound selected from the group consisting of mono- or polyhydric alcohols, amines, amino alcohols and thiols.

3. The use according to claim 1 or 2, wherein the polyisocyanate composition A consists of at least 70% by weight, based on its total weight, of polyisocyanates which have exclusively aliphatically and / or cycloaliphatically bound isocyanate groups.

4. The use according to any one of claims 1 to 3, wherein the polyisocyanate composition A contains at least one blocked polyisocyanate, the blocking agent of which is selected from the group consisting of lactams, oximes, cyclopentanone-2-alkyl esters and phenols.

5. The use according to any one of claims 1 to 4, wherein the workpiece consists of at least one material selected from the group consisting of thermoplastic polymers, thermosetting polymers, wood and metal.

6. A method for coating a workpiece comprising the steps of a) placing a workpiece in a mold which encloses at least part of the workpiece and which is dimensioned such that the distance between the surface of the workpiece and the inside of the shape corresponds to the thickness of the coating ; b) filling in at least one reaction mixture as defined in one of claims 1 to 4; and c) Curing of the reaction mixture filled in process step b) at a temperature between 60 ° C. and 300 ° C., at least 30 mol% of the free isocyanate groups present at the beginning of process step c) being converted to isocyanurate groups.

7. The method of claim 6, wherein step c) is carried out at a temperature between 80 ° C and 130 ° C.

8. The method according to claim 6 or 7, wherein the method step c) is carried out for 10 seconds to 900 seconds and the coated workpiece can be removed from the mold.

9. The method according to any one of claims 6 to 8, wherein the workpiece to be coated consists of at least 90% by weight of a thermoplastic material and said workpiece was manufactured by injection molding at most 5 minutes before the start of process step a).

10. The method according to any one of claims 6 to 9, wherein the distance between the surface of the workpiece and the inside of the mold is 50 μm to 5 mm.

11. The method according to any one of claims 6 to 9, wherein the polyisocyanate composition A contains at least one silane-functional polyisocyanate.

12. Coating obtained or obtainable by the process according to any one of claims 6 to 11.

13. The coating according to claim 12, characterized in that the ratio of the absolute peak heights of the CFh band and the NH-d band is at least 0.85: 1 and the ratio of the absolute peak heights of the isocyanurate band and the NH-d band is at least 5.5: 1 and the coating has a Tg of 40 ° C to 300 ° C.

14. The coating according to claim 12 or 13, characterized in that it has a density of at least 0.95 g / cm ³ .

15. Workpiece coated with the coating according to one of claims 12 to 14.