Two-component polyurethane composition having improved adhesion and adjustable pot life

Abstract

The present invention relates to a polyurethane composition consisting of a first component and a second component, wherein the first component comprises at least one polyol, at least one diol, and at least one compound that has at least one thiol group, and the second component optionally comprises at least one polyol and at least one polyisocyanate, wherein one of the two components additionally contains at least one metal catalyst for the reaction of hydroxyl groups and isocyanate groups, which metal catalyst can form thiol complexes with the thiol-group-containing compound, and wherein the molar ratio of all thiol groups of the at least one compound that has at least one thiol group to all metal atoms of the metal catalyst is between 1:1 and 250:1, and wherein the polyurethane composition additionally contains at least 10 wt.% flame retardant, based on the total polyurethane composition. Such a composition allows the open time of the polyurethane composition to be adjusted as desired within certain limits and makes it possible to achieve long open times with subsequent very rapid curing of the composition, and also has the advantages of a flame-retardant composition and has particularly good adhesion to aluminium substrates. Further aspects of the invention are the use of the polyurethane composition and a method for adhesively bonding substrates, and articles resulting from the adhesive bonding method addressed by the invention. The composition according to the invention is particularly suitable as a structural adhesive for bonding two substrates, in particular in the automotive industry, or as a sealant or casting compound.

Description

[0001] Two-component polyurethane composition with improved adhesion and adjustable pot life

[0002] Technical field

[0003] The invention relates to the field of two-component polyurethane compositions and their use, in particular as adhesives.

[0004] State of the art

[0005] Two-component polyurethane compositions based on polyols and polyisocyanates have been used for a long time.

[0006] Two-component polyurethane compounds have the advantage over one-component compounds that they cure quickly after mixing and can therefore absorb and transmit higher forces in a short time. For use as structural adhesives, such compounds are subject to high demands regarding strength and adhesion, as they are components of load-bearing structures. In particular, these compounds require good mechanical properties in their cured state, such as high tensile and tensile shear strengths, while simultaneously exhibiting a certain degree of elasticity. Furthermore, in industrial manufacturing, for example, it is desirable for such compounds to cure as quickly as possible, even when used as sealants or potting compounds, thus reducing cycle times.

[0007] To achieve the desired mechanical properties and, above all, particularly rapid curing, high proportions of isocyanates are advantageous in such compositions. These isocyanates are present in one of the two components as free or polymer-bound polyisocyanates and cure upon mixing with the other component, which contains polyols, forming a polymeric network. However, a high isocyanate content leads to problems. Especially when using crosslinking catalysts, which are essential for selective, optimal crosslinking and curing, such two-component systems become almost uncontrollably fast, and the pot lives are far too short for an application like the one described above.

[0008] For the application of two-component polyurethane compounds, it is generally desirable to combine a sufficiently long pot life with subsequent very rapid curing and exceptionally fast strength development. However, this is hardly achievable with current two-component compounds. Either the pot life is very short for compounds that cure and build strength quickly, or the curing and strength development are slow when compounds with a long pot life are used.

[0009] Therefore, two-component polyurethane compositions were developed that have a long pot life, which can even be adjusted within certain limits, so that processing of larger construction or manufacturing parts is possible, but which also cure very quickly after application and exhibit strength and elasticity in the sense of structural bonding within an extremely short time, e.g. hours to a few days.

[0010] Such a two-component polyurethane composition is disclosed in EP3645594B1. This publication teaches special catalyst systems comprising a metal catalyst and thiol-containing compounds, which allow for an adjustable, long pot life and subsequent very rapid curing of the composition. Furthermore, EP4127008A1 describes a two-component polyurethane composition with high hydrophobicity and an adjustable pot life.

[0011] WO 2023 / 031304 A1, as a further example, discloses a three-component polyurethane composition with the same catalyst system, but divided into three components: a polyol component containing the thiol compound, a catalyst component, and a polysiocyanate component. These compositions are particularly suitable as laminating adhesives.

[0012] Another example is WO 2022 / 167403 A1. This publication also discloses the same catalyst system. However, the claimed composition additionally comprises microscopic hollow spheres and a drying agent and is particularly suitable as a wood filler.

[0013] With the increasing use of batteries and electronic devices, the demand for suitable structural adhesives for contact with these electronic components or devices has risen considerably. In the assembly of electric vehicles, the large and heavy batteries and numerous electronic parts are often installed in a battery box, which is bonded with a structural adhesive. The battery box is often made of aluminum, as this material allows for a reduction in the weight of the heavy components. However, aluminum is very difficult to bond with conventional adhesive compositions.

[0014] A key requirement for these adhesives is high fire resistance, as batteries and electronics generate significant amounts of heat during operation, and a malfunction, such as a short circuit, can lead to a battery fire. It would therefore be desirable to obtain a two-component polyurethane compound that incorporates a catalyst system offering a long, adjustable pot life and subsequent extremely rapid curing, while also providing the advantages of a flame-retardant composition, particularly for bonding such battery boxes. Furthermore, such a compound must be able to establish sufficiently strong adhesion to the metal surface to be bonded, especially aluminum. Adhesion to aluminum, in particular, often poses a significant challenge for conventional two-component polyurethane adhesives.Adhesives with adjustable pot life, as disclosed in EP3645594B1, also exhibit insufficient adhesion to aluminum substrates. Description of the invention.

[0015] The object of the present invention is therefore to provide a two-component polyurethane composition with adjustable pot life that meets the requirements of an application as an adhesive in the automotive sector, in particular good adhesion to aluminium should be achieved.

[0016] Surprisingly, this problem is solved with the polyurethane composition according to claim 1.

[0017] In its cured state, the composition exhibits good mechanical properties, in particular high tensile shear strength and elasticity, and adequate elongation at break, and displays excellent flame retardancy (V0) as measured according to UL94. After mixing the components, the composition cures very quickly after a sufficiently long pot life, which can be adjusted within certain limits, and achieves very good mechanical properties after only a short time, e.g., a few hours to a day. Surprisingly, the composition according to the invention also exhibits exceptionally good adhesion to metal, especially aluminum.

[0018] Further aspects of the invention are the subject of further independent claims. These include the use of the polyurethane composition and a method for bonding substrates, as well as articles derived from the bonding method. Particularly preferred embodiments of the invention are the subject of the dependent claims.

[0019] Ways to implement the invention

[0020] The present invention relates to a polyurethane composition comprising a first component A and a second component B, wherein the first component A comprises at least one polyol P; at least one diol O having an average molecular weight of less than 250 g / mol; at least one compound T having at least one thiol group; and

[0021] - The second component B optionally comprises a polyol P; at least one polyisocyanate I; wherein one of the two components A and B additionally contains at least one metal catalyst K for the reaction of hydroxyl groups and isocyanate groups, which can form thiol complexes with compound T, and wherein the molar ratio of all thiol groups of the at least one compound T to all metal atoms of the metal catalyst K is between 1 :1 and 250:1, and wherein the polyurethane composition additionally contains at least 10 wt%, based on the total polyurethane composition, of a flame retardant F.

[0022] The prefix "Poly" in substance names such as "Polyol", "Polyisocyanate", "Polyether" or "Polyamine" indicates in this document that the respective substance formally contains more than one of the functional groups appearing in its name per molecule.

[0023] In this document, the term "polymer" encompasses, on the one hand, a group of chemically uniform macromolecules that differ in degree of polymerization, molar mass, and chain length, and which are produced by a polymerization reaction (polymerization, polyaddition, polycondensation). On the other hand, the term also includes derivatives of such a group of macromolecules from polymerization reactions; that is, compounds obtained by changes, such as additions or substitutions, of functional groups on given macromolecules, and which may be chemically uniform or chemically heterogeneous. Furthermore, the term also includes so-called prepolymers, that is, reactive oligomeric pre-adducts whose functional groups are involved in the construction of macromolecules.

[0024] The term "polyurethane polymer" encompasses all polymers produced using the so-called diisocyanate polyaddition process. This also includes polymers that are almost or entirely free of urethane groups. Examples of polyurethane polymers are polyether polyurethanes, polyester polyurethanes, polyether polyureas, polyureas, polyester polyureas, polyisocyanurates, and polycarbodiimides.

[0025] In this document, "molecular weight" refers to the molar mass (in grams per mole) of a molecule or molecular residue.

[0026] The number mean M is called the "mean molecular weight". n a polydisperse mixture of oligomeric or polymeric molecules or molecular residues, which is usually determined by gel permeation chromatography (GPC) against polystyrene as a standard.

[0027] Weight percent, abbreviated wt%, denotes the mass fraction of a component in a composition, based on the total composition, unless otherwise specified. The terms "mass" and "weight" are used synonymously in this document.

[0028] A "primary hydroxyl group" is an OH group that is bonded to a carbon atom with two hydrogens.

[0029] In this document, "pot life" refers to the time within which the polyurethane composition can be processed after mixing the two components, before the viscosity becomes too high for further processing due to the progress of the crosslinking reaction. The term "strength" in this document refers to the strength of the cured composition, specifically tensile strength and the modulus of elasticity (Young's modulus), particularly in the elongation range of 0.05 to 0.25% or in the range of 0.5 to 5.0%.

[0030] In this document, "room temperature" is defined as a temperature of 23±1 °C.

[0031] In this document, "standard conditions" or "normal conditions" refers to the standard temperature of 25°C and the standard pressure of 1013 hPa.

[0032] A substance or composition is described as "storage-stable" or "storable" if it can be stored at room temperature in a suitable container for a longer period of time, typically at least 3 months up to 6 months or more, without its application or usage properties, in particular viscosity and crosslinking rate, changing to an extent relevant to its use.

[0033] The "mean OH functionality" represents the number of OH groups per polymer molecule, averaged across all polymer molecules. For example, if 50% of all polymer molecules contain two hydroxyl groups and the other 50% contain three, the mean OH functionality is 2.5. The mean OH functionality can be calculated, in particular, from the hydroxyl number and the molecular weight M determined via GPC. n to be determined.

[0034] The "OH number" or "hydroxyl number" is used to indicate the reactive equivalents of the hydroxyl groups in a polyol and is expressed in [mg KOH / g polyol]. "Flame retardants" are additives that are mixed into a plastic compound, such as a polyurethane compound, and are intended to limit, slow down, or prevent the flammability of that compound. A common method for assessing and classifying the flammability of plastics corresponds to the UL 94 standard (Test for Flammability of Plastic Materials for Parts in Devices and Appliances).

[0035] The "pot life" of a compound refers to the period of time during which a freshly prepared adhesive remains workable. Pot life can be measured by measuring viscosity. For example, the time it takes for a mixed, two-component polyurethane compound, particularly at room temperature, to reach a viscosity of 500 Pa s can be defined as the pot life.

[0036] Unless otherwise stated, all industry standards and norms mentioned in this document refer to the versions valid at the time of initial filing.

[0037] The polyurethane composition according to the invention consists of a first component A and a second component B, which are only mixed when the polyurethane composition is applied and are previously stored in separate packaging.

[0038] Polyol P

[0039] In principle, all commercially available polyols suitable for polyurethane production can be used as polyols P.

[0040] In a preferred embodiment, the polyurethane composition is characterized in that the polyol P has a medium OH functionality in the range of 2 to 4 and / or a medium molecular weight in the range of 250 to 10,000 g / mol and / or an OH number in the range of 250 to 600 mg KOH / g. In preferred embodiments, the polyol P has a medium OH functionality in the range of 2 to 4, in particular 2 to 3.5, especially preferably 2 to 3, and most preferably 2 to 2.5.

[0041] In preferred embodiments, the polyol P has an average molecular weight in the range of 250 to 10,000 g / mol, in particular 500 to 5,000 g / mol, particularly preferably 750 to 3,500 g / mol, most preferably 1,000 to 3,000 g / mol.

[0042] In preferred embodiments, the polyol P has a hydroxyl number in the range of 25 to 600 mg KOH / g, in particular 50 to 500 mg KOH / g, particularly preferably 50 to 250 mg KOH / g, most preferably 50 to 200 mg KOH / g.

[0043] Polybutadiene polyols are particularly preferred as polyol P.

[0044] Preferred polyols P are polybutadiene polyols with a mean molecular weight in the range of 2,000 to 10,000 g / mol and a mean OH functionality in the range of 2 to 4.

[0045] The mean molecular weight of the polybutadiene polyol is preferably in the range of 2,000 to 4,000 g / mol, particularly in the range of 2,500 to 3,000 g / mol.

[0046] The average OH functionality of the polybutadiene polyol is preferably in the range of 2.1 to 2.9, particularly in the range of 2.3 to 2.7.

[0047] Such a polybutadiene polyol is readily available and has a comparatively low viscosity, which allows for good processability of the composition.

[0048] Suitable polybutadiene polyols are particularly available through

[0049] Polymerization of 1,3-butadiene and allyl alcohol in a suitable ratio or by oxidation of suitable polybutadienes, as well as their hydrogenation products.

[0050] Suitable polybutadiene polyols contain in particular structural elements of formula (I) and optionally structural elements of formula (II) or (III). )

[0051] A preferred polybutadiene polyol contains

[0052] 40 to 80 wt.%, in particular 55 to 65 wt.% of the structural element of formula (I)

[0053] 0 to 30 wt.%, in particular 15 to 25 wt.%, of the structural element of formula (II),

[0054] 0 to 30 wt.%, in particular 15 to 25 wt.%, of the structural element of formula (III).

[0055] A particularly suitable polybutadiene polyol is PolyBD® R-45 HTLO or PolyBD® R-45 M (both from Cray Valley).

[0056] Polycarbonate polyols are also particularly suitable as polyols P.

[0057] Particularly suitable as polycarbonate polyols are those obtained, for example, by reacting the alcohols mentioned above (used in the synthesis of polyester polyols) with dialkyl carbonates such as dimethyl carbonate, diaryl carbonates such as diphenyl carbonate, or phosgene. Polycarbonates obtained from the copolymerization of CO2 with epoxides such as ethylene oxide and propylene oxide are also suitable.

[0058] A particularly suitable aliphatic polycarbonate polyol is based on 3-methyl-1,5-pentanediol and 1,6-hexanediol and is available, for example, under the trade name Kuraray® C-2050 from the company Kuraray.

[0059] A particularly suitable aliphatic polyester carbonate polyol based on 1,6-hexanediol and s-caprolactone is available from Bayer Material Science under the trade name Desmophen® C 1200.

[0060] Polyester polyols, especially dimer fatty acid-based polyester polyols, are particularly preferred as polyol P.

[0061] Particularly preferred as polyol P are dimer fatty acid-based polyester polyols, which are obtained from oleo-based (renewable) raw materials.

[0062] Preferably, such a dimer fatty acid-based polyester polyol is liquid at room temperature. It particularly exhibits an OH number in the range of 28 to 120 mg KOH / g.

[0063] Such dimer fatty acid-based polyester polyols have an average molecular weight in the range of 950 to 4,000 g / mol. They are mostly largely linear in structure and have an average OH functionality of about 2, particularly between 2 and 2.5.

[0064] Preferably, the dimer fatty acid-based polyester polyol is amorphous. Dimer fatty acid-based polyester polyols suitable as polyol P are obtained in particular from the esterification of at least one dimer fatty acid and / or at least one dimer fatty alcohol with a diol, such as diethylene glycol or butanediol, and / or a dicarboxylic acid, such as adipic acid, at a stoichiometry such that the product is amorphous and liquid at room temperature and has an OH number in the range of 28 to 120 mg KOH / g.

[0065] Preferably, the dimer fatty acid-based polyester polyol contains a carbon content from renewable sources according to ASTM D6866, based on the total carbon content, in the range of 50 to 100%, preferably 60 to 95%, and particularly 70 to 90%. Such a polyester polyol is amorphous, hydrophobic, and particularly compatible with polyurethane adhesives.

[0066] Preferably, the dimer fatty acid-based polyester polyol used as polyol P has an OH number in the range of 34 to 120 mg KOH / g, particularly 52 to 60 mg KOH / g. Such a dimer fatty acid-based polyester polyol has a mean molecular weight in the range of 950 to 3,300 g / mol, particularly in the range of 1,900 to 2,200 g / mol. Such a polymer enables polyurethane compositions with a particularly attractive combination of good extrudability, good adhesion properties, and high strength.

[0067] Suitable materials include commercially available amorphous dimer fatty acid-based polyester polyols, especially the types Priplast® 1837, 1838, 3187, 3196, 3197, 3199 or 3238 (from Croda), available under the trade name Priplast®. Priplast® 1838 is preferred. Solvermol® types (from BASF), especially Solvermol® RC 1005 and Solvermol® 805, are also suitable.

[0068] Polyester polyols suitable as polyol P are in particular polyesters which bear at least two hydroxyl groups and are produced by known processes, in particular the polycondensation of hydroxycarboxylic acids or the polycondensation of aliphatic and / or aromatic polycarboxylic acids with dihydric or polyhydric alcohols.Particularly suitable are polyester polyols which are produced from di- to trihydric alcohols such as 1,2-ethanediol, diethylene glycol, 1,2-propanediol, dipropylene glycol, or mixtures of the aforementioned alcohols with organic dicarboxylic acids or their anhydrides or esters such as succinic acid, glutaric acid, adipic acid, trimethyladipic acid, maleic acid, fumaric acid, phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid, dimethyl terephthalate, hexahydrophthalic acid, trimellitic acid and trimellitic anhydride or mixtures of the aforementioned acids, as well as polyester polyols made from lactones such as s-caprolactone.

[0069] Suitable polyester polyols include, for example, those available under the trade name Kuraray® from Kuraray, in particular Kuraray® F-510, and those available under the trade name K-Flex® from King Industries, in particular K-Flex® 188.

[0070] Particularly preferred polyether polyols comprise polyether polyols with a repeating unit having at least 4 carbon atoms between two ether oxygens, for example a poly(propylene glycol) polyol, a poly(tetramethylene glycol) polyol, a poly(ethylene glycol) polyol, or a poly(butylene glycol) polyol. Mixtures of these polyether polyols are particularly preferred, especially mixtures of poly(propylene glycol) polyols with poly(ethylene glycol) polyols.

[0071] Adiansol® TO 470, available from Arkema, is particularly suitable as a poly(butylene glycol) polyol.

[0072] Also particularly suitable as polyol P are so-called ethylene oxide-terminated ("EO-endcapped," ethylene oxide-endcapped) polyoxypropylene polyols. These are special polyoxypropylene polyoxyethylene polyols obtained, for example, by further alkoxylating pure polyoxypropylene polyols, especially polyoxypropylene diols and triols, with ethylene oxide after completion of the polypropoxylation reaction, thereby giving them primary hydroxyl groups. Polyoxypropylene polyoxyethylene diols and polyoxypropylene polyoxyethylene triols are preferred in this case.

[0073] Suitable such polyether-based polyols P are available, for example, under the trade names Acclaim® and Desmophen® from Covestro, in particular Acclaim® 4200, Desmophen® 5034, Desmophen® 1381 BT and Desmophen® 28HS98, under the trade name Voranol® from Dow, in particular Voranol® EP 1900 and Voranol® CP 4755, and under the trade name Dianol® from Arkema, in particular Dianol® 3130 HP.

[0074] Styrene-acrylonitrile grafted polyether polyols, such as those commercially available under the trade name Lupranol® from Elastogran GmbH, Germany, are also suitable as polyol P.

[0075] Also suitable as polyol P are polyhydrocarbon polyols, also called oligohydrocarbonols, for example polyhydroxy-functional ethylene-propylene, ethylene-butylene or ethylene-propylene-diene copolymers, such as those produced by Kraton Polymers, USA, or polyhydroxy-functional copolymers of dienes such as 1,3-butanediene or diene mixtures and vinyl monomers such as styrene, acrylonitrile or isobutylene, or polyhydroxy-functional polybutadiene polyols, for example those produced by copolymerization of 1,3-butadiene and allyl alcohol, which may also be hydrogenated.

[0076] Further suitable polyols P include polyhydroxy-functional acrylonitrile / butadiene copolymers, such as those produced from epoxides or amino alcohols and carboxyl-terminated acrylonitrile / butadiene copolymers, which are commercially available under the name Hypro® (formerly Hycar®) CTBN from Emerald Performance Materials, LLC, USA. In a preferred embodiment, the polyurethane composition is characterized in that the polyol P comprises polybutadiene polyols, polycarbonate polyols, polyester polyols, polyether polyols, poly(meth)acrylate polyols, or a mixture of these polyols.

[0077] In a further preferred embodiment, the polyol P is preferably an aliphatic or cycloaliphatic polyol with a mean OH functionality of between 2 and 4, which is free of aromatic components.

[0078] Preferably, aliphatic or cycloaliphatic polyols are used, preferably a polytetramethylene oxide diol or a polycarbonate diol based on 3-methyl-1,5-pentanediol and 1,6-hexanediol, or a polyester carbonate diol based on 1,6-hexanediol and s-caprolactone or a polyester diol based on 3-methyl-1,5-pentanediol and adipic acid or sebacic acid.

[0079] A particularly suitable polyester polyol is a condensation product of 3-methyl-1,5-pentanediol and adipic acid or sebacic acid. Such polyester polyols are available, for example, under the trade name Kuraray® P-2010 from the company Kuraray.

[0080] In a preferred embodiment, the polyol P is present in both component A and component B.

[0081] Preferably, component A contains, based on the total composition of component A, 10 to 40 wt.%, particularly preferably 15 to 35 wt.%, most preferably 20 to 30 wt.% of the polyol P.

[0082] Preferably, component B contains, based on the total composition of component B, 25 to 75 wt.%, particularly preferably 30 to 60 wt.%, most preferably 35 to 55 wt.% of the polyol P. Diol O.

[0083] Diol O is a dihydric alcohol, in particular an aliphatic diol or a diol bridged via an aliphatic chain. Diol O has an average molecular weight of less than 250 g / mol, preferably a maximum of 200 g / mol, and particularly preferably a maximum of 150 g / mol.

[0084] In a preferred embodiment, the polyurethane composition is characterized in that the diol O is a linear aliphatic diol with two primary hydroxyl groups linked via a C2 to C9 carbon chain, in particular selected from the group consisting of 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol and 1,9-nonanediol.

[0085] Suitable diols are linear or branched alkylenediols with two primary or secondary hydroxyl groups, alkylenediols with one primary and one secondary hydroxyl group, and cycloaliphatic diols.

[0086] Preferably, the diol O is a linear aliphatic diol with two primary hydroxyl groups linked via a C4 to C9 carbon chain. Such a diol has the advantage that polyurethanes with particularly high moduli of elasticity in the low elongation range, for example between 0 and 5%, can be obtained, which is particularly advantageous for structural adhesives.

[0087] In particular, diol O is selected from the group consisting of ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,3-butanediol, 2,3-butanediol, 2-methyl-1,3-propanediol, 1,2-pentanediol, 2,4-pentanediol, 2-methyl-1,4-butanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 1,2-hexanediol, 1,4-butanediol, 3-methyl-1,5-pentanediol, 1,2-octanediol, 3,6-octanediol, 2-Ethyl-1,3-hexanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-butyl-2-ethyl-1,3-propanediol, 2,7-dimethyl-3,6-octanediol, 1,4-cyclohexanediol, 1,3-cyclohexanedimethanol and 1,4-cyclohexanedimethanol.Other low-molecular-weight dihydric alcohols, such as diethylene glycol, triethylene glycol, the isomeric dipropylene and tripropylene glycols, the isomeric decanediols and undecanediols, hydrogenated bisphenol A, dimeric fatty alcohols, 1,1,1-trimethylolpropane, glycerol, pentaerythritol, sugar alcohols such as xylitol, sorbitol, or mannitol, as well as mixtures of the aforementioned alcohols, are also suitable as diols. Furthermore, diols containing other heteroatoms, such as methyldiethanolamine or thiodiglycol, can also be suitable as diols.

[0088] Particularly preferred is the diol O selected from the group consisting of 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol and 1,9-nonanediol.

[0089] The most preferred diol is selected from the group consisting of 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, and 1,9-nonanediol. These diols are commercially readily available and enable polyurethanes with particularly high moduli of elasticity and low elongation after curing.

[0090] In a preferred embodiment, the diol O is present in component A.

[0091] Preferably, component A contains, based on the total composition of component A, 1 to 5 wt.%, particularly preferably 1.5 to 4.5 wt.%, most preferably 2 to 4 wt.% of diol O.

[0092] Connection T

[0093] The first component A further contains at least one compound T having at least one thiol group. Suitable compounds are those having at least one thiol group that can be formulated according to the invention. Here, a thiol group is understood to be an -SH group bonded to an organic residue, for example, an aliphatic, cycloaliphatic, or aromatic carbon residue.

[0094] Compounds with 1 to 6, particularly 1 to 4, and most preferably 1 or 2 thiol groups are preferred. Compounds with one thiol group have the advantage that no complexes with the metal catalyst K, which tend to be sparingly soluble, are formed, and the pot life can be adjusted particularly precisely. Compounds with two thiol groups have the advantage that the mechanical properties of the composition are improved after curing.

[0095] In a preferred embodiment, the polyurethane composition is characterized in that the compound T, which has at least one thiol group, comprises a compound with 1 to 6 thiol groups.

[0096] Suitable compounds T with a thiol group are, for example, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercapto-1,2-propanediol, 2-mercaptotoluimidazole or 2-mercaptobenzothiazole.

[0097] Mercaptosilanes are particularly preferred as compounds T with a thiol group.

[0098] Suitable compounds T with more than one thiol group are, for example, ethylene glycol di(3-mercaptopropionate), ethylene glycol dimercaptoacetate, dipentaerythritol hexa(3-mercaptopropionate), 2,3-dimercapto-1,3,4-thiadiazole or pentaerythritol tetrakis(3-mercaptopropionate).

[0099] In a preferred embodiment, the polyurethane composition is characterized in that the compound T, which has at least one thiol group, is selected from the group consisting of ethylene glycol di(3-mercaptopropionate), ethylene glycol dimercaptoacetate, dipentaerythritol hexa(3-mercaptopropionate), and 3-mercaptopropyltrimethoxysilane. The amount of compound T in the first component A is preferably in the range of 0.1 to 5 wt.%, more preferably 0.2 to 2.5 wt.%, and in particular 0.25 to 1.0 wt.%, based on component A.

[0100] The amount of compound T, based on the total polyurethane composition, is preferably in the range of 0.04 to 2.0 wt.%, preferably 0.08 to 1.0 wt.%, in particular 0.1 to 0.4 wt.%, based on the total polyurethane composition.

[0101] The second component B contains at least one polyisocyanate I.

[0102] All commercially available polyisocyanates suitable for polyurethane production, in particular diisocyanates, can be used as polyisocyanates I for the production of the polyurethane polymer in the composition according to the invention.

[0103] In a preferred embodiment, the polyurethane composition is characterized in that the polyisocyanate I is a liquid form at room temperature of 4,4'-, 2,4'- or 2,2'-diphenylmethane diisocyanate and any mixtures of these isomers (MDI) in the form of polymeric MDI or MDI with proportions of oligomers or derivatives, in particular carbodiimides.

[0104] Suitable polyisocyanates are in particular monomeric di- or triisocyanates, as well as oligomers, polymers and derivatives of the monomeric diisocyanates or triisocyanates, and any mixtures thereof.

[0105] Suitable aromatic monomeric di- or triisocyanates include, in particular, 2,4- and 2,6-toluene diisocyanate and any mixtures of these isomers (TDI), 4,4'-, 2,4'- and 2,2'-diphenylmethane diisocyanate and any mixtures of these isomers (MDI), mixtures of MDI and MDI homologs (polymeric MDI or PMDI), 1,3- and 1,4-phenylene diisocyanate, 2,3,5,6-tetramethyl-1,4-diisocyanatobenzene, naphthalene-1,5-diisocyanate (NDI), 3,3'-dimethyl-4,4'-diisocyanatodiphenyl (TODI), dianisidine diisocyanate (DADI), 1,3,5-tris-(isocyanatomethyl)benzene, tris-(4-isocyanatophenyl)methane and tris-(4-isocyanatophenyl)thiophosphate.

[0106] Suitable aliphatic monomeric di- or triisocyanates include, in particular, 1,4-tetramethylene diisocyanate, 2-methylpentamethylene-1,5-diisocyanate, 1,6-hexamethylene diisocyanate (HDI), 2,2,4- and 2,4,4-trimethyl-1,6-hexamethylene diisocyanate (TMDI), 1,10-decamethylene diisocyanate, 1,12-dodecamethylene diisocyanate, lysine and lysine ester diisocyanate, cyclohexane-1,3- and -1,4-diisocyanate, 1-methyl-2,4- and -2,6-diisocyanatocyclohexane and any mixtures of these isomers (HTDI or HeTDI), 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethyl-cyclohexane (=isophorone diisocyanate or IPDI). Perhydro-2,4'- and -4,4'-diphenylmethane diisocyanate (HMDI or H12MDI), 1,4-Diisocyanato-2,2,6-trimethylcyclohexane (TMCDI), 1,3- and 1,4-Bis-(isocyanatomethyl)cyclohexane, m- and p-xylylene diisocyanate (m- and p-XDI), m- and p-Tetramethyl-1,3- and -1,4-xylylene diisocyanate (m- and p-TMXDI), Bis-(1-isocyanato-1-methylethyl)naphthalene, dimer and trimer fatty acid isocyanates such as 3,6-Bis-(9-isocyano-natononyl)-4,5-di-(1-heptenyl)cyclohexene (dimeryl diisocyanate) and α,α,α',α',α",α"-hexamethyl-1,3,5-mesitylene triisocyanate.

[0107] The preferred technologies are MDI, TDI, HDI and IPDI.

[0108] Suitable oligomers, polymers and derivatives of the aforementioned monomeric di- and triisocyanates are in particular derived from MDI, TDI, HDI and IPDI.Particularly suitable are commercially available types, especially HDI biuretes such as Desmodur® N 100 and N 3200 (from Covestro), Tolonate® HDB and HDB-LV (from Vencorex) and Duranate® 24A-100 (from Asahi Kasei); HDI isocyanurates, such as Desmodur® N 3300, N 3600 and N 3790 BA (all from Covestro), Tolonate® HDT, HDT-LV and HDT-LV2 (from Vencorex), Duranate® TPA-100 and THA-100 (from Asahi Kasei) and Coronate® HX (from Nippon Polyurethane); HDI uretdiones such as Desmodur® N 3400 (from Covestro); HDI iminooxadiazindiones such as Desmodur® XP 2410 (from Covestro); HDI allophanes such as Desmodur® VP LS 2102 (from Covestro); IPDI isocyanurates, such as in solution as Desmodur® Z 4470 (from Covestro) or in solid form as Vestanat® T1890 / 100 (from Evonik); TDI oligomers such as Desmodur® IL (from Covestro); and mixed isocyanurates based on TDI / HDI, for example as Desmodur® HL (from Covestro).

[0109] Also particularly suitable are liquid forms of MDI at room temperature (so-called "modified MDI"), which represent mixtures of MDI with MDI derivatives, such as in particular MDI carbodiimides or MDI uretonides or MDI urethanes, known under trade names such as Desmodur® CD, Desmodur® PF, Desmodur® PC (all from Covestro) or Isonate® M 143 (from Dow), as well as mixtures of MDI and MDI homologs (polymeric MDI or PMDI), available under trade names such as Desmodur® VL, Desmodur® VL50, Desmodur® VL R10, Desmodur® VL R20, Desmodur® VH 20 N and Desmodur® VKS 20F (all from Covestro), Isonate® M 309, Voranate® M 229 and Voranate® M 580 (all from Dow) or Lupranat® M 10 R (from BASF). The aforementioned oligomeric polyisocyanates typically represent mixtures of substances with different degrees of oligomerization and / or chemical structures in practice. Preferably, they exhibit a medium NCO functionality of 2.1 to 4.0.

[0110] Preferably, the polyisocyanate is selected from the group consisting of MDI, TDI, HDI and IPDI and oligomers, polymers and derivatives of the aforementioned isocyanates, as well as mixtures thereof.

[0111] Preferably, the polyisocyanate contains isocyanurate, iminooxadiazin ione, uret dione, biuret, allophane, carbodiimide, uretonimine or oxadiazintrione groups.

[0112] Particularly preferred as polyisocyanates are liquid forms of MDI at room temperature. These are especially so-called polymeric MDI and MDI containing oligomers or derivatives thereof. The MDI content (=4,4'-, 2,4'-, or 2,2'-diphenylmethane diisocyanate and any mixtures of these isomers) of such liquid forms of MDI is particularly 50 to 95 wt.%, and more specifically 60 to 90 wt.%. Particularly preferred as polyisocyanates are polymeric MDI and MDI types that are liquid at room temperature and contain MDI carbodiimides or their adducts. These polyisocyanates exhibit particularly good processing properties and especially high strength.

[0113] The polyisocyanate of the second component B may contain proportions of polyurethane polymers containing isocyanate groups. Either the second component may comprise a separately produced polyurethane polymer containing isocyanate groups, or the polyisocyanate may have been mixed with at least one polyol, in particular a polyether polyol, wherein the isocyanate groups are present in a stoichiometric excess relative to the OH groups.

[0114] In the second component B of the composition according to the invention, polyisocyanate I is preferably present in an amount of 15 wt.% to 70 wt.%, in particular 20 wt.% to 65 wt.%, and especially preferably 25 wt.% to 60 wt.%, based on the second component B.

[0115] The polyurethane composition preferably contains such a quantity of polyisocyanate I that at least 5 wt.%, in particular at least 6 wt.%, preferably at least 7.5 wt.%, based on the total polyurethane composition, contains polyisocyanate I.

[0116] Metal catalyst K

[0117] The first component A and / or the second component B further contains at least one metal catalyst K for the reaction of hydroxyl and isocyanate groups, which can form thiol complexes with compound T. Therefore, all metal catalysts suitable as metal catalysts are those that can be used as crosslinking catalysts in polyurethane chemistry and can simultaneously form thiol complexes with thiols in their presence. Suitable catalysts include, for example, bismuth, zinc, tin, or zirconium compounds, which includes complexes and salts of these metals.

[0118] Preferably, the metal catalyst K comprises a bismuth compound, in particular a bismuth(III) compound. A bismuth compound has the advantage that, in addition to the desired properties as a catalyst and thiol complex former, it possesses low acute toxicity.

[0119] A variety of conventional bismuth catalysts can be used as bismuth compounds. These include, for example, bismuth carboxylates such as bismuth acetate, oleate, octoate, or neodecanoate; bismuth nitrate; bismuth halides such as bromide, chloride, iodide, and bismuth sulfide; basic bismuth carboxylates such as bismutyl neodecanoate, bismuth subgallate, or bismuth subsalicylate; and mixtures thereof.

[0120] In a preferred embodiment, the polyurethane composition is characterized in that the metal catalyst K comprises a tin(IV) compound and / or a bismuth(III) compound.

[0121] In a preferred embodiment, the polyurethane composition is characterized in that the metal catalyst comprises ligands selected from the group consisting of alkyl ligands, carboxylate ligands, hydroxyquinoline ligands and / or 1,3-ketoamide ligands.

[0122] In a preferred embodiment, the metal catalyst K is a bismuth(III) complex comprising at least one 8-hydroxyquinoline-based ligand. Such complexes are described in EP1551895. Preferably, this is a bismuth(III) carboxylate comprising one molar equivalent of an 8-hydroxyquinoline ligand.

[0123] In a further preferred embodiment, the metal catalyst K is a bismuth(III) complex comprising at least one 1,3-ketoamide-based ligand. Such complexes are described in EP2791153. Preferably, this is a bismuth(III) carboxylate comprising 1 to 3 molar equivalents of a 1,3-ketoamide ligand.

[0124] In a preferred embodiment, the polyurethane composition is characterized in that the metal catalyst K is included in the first component A.

[0125] Preferably, the metal catalyst K is contained only in the first component A. This has the advantage of achieving better storage stability. In this embodiment, the amount of metal catalyst K in the first component A is preferably in the range of 0.01 to 2.5 wt.%, more preferably 0.1 to 2.0 wt.%, particularly 0.2 to 1.5 wt.%, and most preferably 0.25 to 1.0 wt.%, based on the first component A.

[0126] If the catalyst is present in the second component B, the same preferred quantity ranges apply as described above, but with reference to component B.

[0127] The amount of metal catalyst K, based on the total polyurethane composition, is preferably in the range of 0.02 to 1.0 wt.%, preferably 0.025 to 0.8 wt.%, in particular 0.08 to 0.6 wt.%, and especially preferably 0.1 to 0.5 wt.%, based on the total polyurethane composition.

[0128] In a preferred embodiment, the polyurethane composition is characterized in that the molar ratio of all thiol groups of the at least one compound T to all metal atoms of the metal catalyst K is between 1:1 and 250:1, preferably between 2:1 and 150:1, in particular between 5:1 and 100:1.

[0129] This ratio of components allows the pot life to be adjusted within the intrinsic limits of the respective composition, determined, for example, by the catalyst content, the reactivity of the isocyanates present, and their quantity. The lower limit of the pot life is the pot life obtained in a given composition using a specific amount of catalyst without the addition of compound T.

[0130] The upper limit of the adjustable pot life is therefore the pot life that would be achieved without the use of a catalyst due to the uncatalyzed isocyanate-hydroxyl reaction. This reaction begins to start eventually after mixing the two components, even without a catalyst. However, without a catalyst, the reaction proceeds more slowly and results in the hardened material exhibiting inferior mechanical properties.

[0131] The key advantage achieved by the inventive two-component polyurethane composition is an exceptionally fast-curing and strength-building system that simultaneously exhibits a sufficiently long pot life for user-friendly processing. This allows, for example, structural bonding to be carried out even on larger substrates, which can be subjected to mechanical stress very soon after the adhesive is applied. This leads, for instance, to a significant reduction in cycle times in industrial manufacturing. A further advantage of the inventive polyurethane compositions is the ability to adjust the pot life as described above.This is particularly advantageous for automated applications and can, for example, enable further optimization of cycle times in industrial manufacturing, as the pot life can be adjusted to the desired application.

[0132] Flame retardant F

[0133] The composition according to the invention contains at least one flame retardant F. Suitable flame retardants F are solid or liquid. In a preferred embodiment, the polyurethane composition is characterized in that the flame retardant F is solid under standard conditions.

[0134] Particularly preferred are phosphorus-based flame retardants F, especially organophosphorus compounds such as organophosphoric acid esters such as triethyl phosphate, tricresyl phosphate, triphenyl phosphate, diphenylcresyl phosphate, isodecyldiphenyl phosphate, tris(1,3-dichloro-2-propyl) phosphate, tris(2-chloroethyl) phosphate, tris(2-ethylhexyl) phosphate, tris(chloroisopropyl) phosphate, tris(chloropropyl) phosphate, isopropylated triphenyl phosphate, mono-, bis- or tris(isopropylphenyl) phosphates of varying degrees of isopropylation, resorcinol bis(diphenyl phosphate), bisphenol A bis(diphenyl phosphate) or ammonium polyphosphates.

[0135] Trialkyl and / or triaryl phosphate flame retardants F such as tris-(2-ethylhexyl) phosphate (marketed by Lanxess under the trade name Disflamoll® TOF), cresyldiphenyl phosphate, tricresyl phosphate and triphenyl phosphate (all marketed by Lanxess under the trade name Disflamoll®) are preferred.

[0136] Aliphatic phosphoramidates, which are particularly preferred when present as solids under standard conditions, are especially favored. Particularly preferred are aliphatic phosphoramidates such as N,N'-bis(5,5-dimethyl-1,3,2-dioxaphosphinane-2-oxide-2-yl)ethane-1,2-diamine (for example, marketed by Daihachi Chemical under the trade name Daiguard-850) or fine-grained ammonium polyphosphate (for example, marketed by Clariant under the trade name Exolit® AP 422).

[0137] Also suitable as flame retardants (F) are flame-retardant fillers such as hydroxides or hydrates that release water under heat, in particular hydroxides or hydrates of aluminum, for example, aluminum hydroxides and / or magnesium hydroxides, as well as boron nitride. Aluminum hydroxides such as precipitated aluminum hydroxide (for example, marketed by Huber Advanced Materials under the trade name Martinal OL-104 LEO) are particularly preferred.

[0138] In a preferred embodiment, the polyurethane composition is characterized in that the flame retardant F comprises an organophosphorus compound, in particular phosphoramidates and / or phosphates, methane hydroxides, in particular aluminium hydroxides.

[0139] The composition according to the invention contains at least 10 wt.%, based on the total polyurethane composition, of a flame retardant F. In particularly preferred embodiments, the composition according to the invention contains at least 15 wt.%, particularly preferably at least 20 wt.%, and most preferably 30 wt.%, based on the total polyurethane composition, of a flame retardant F.

[0140] In a particularly preferred embodiment, the polyurethane composition is characterized in that the flame retardant F comprises a combination of aliphatic phosphoramidate, preferably in a range of 5 to 20 wt.%, fine-grained ammonium polyphosphate, preferably in a range of 10 to 30 wt.%, and precipitated aluminum hydroxide, preferably in a range of 20 to 60 wt.%, all based on the first component A.

[0141] The composition according to the invention preferably contains in component A between 15 and 80 wt.%, preferably between 20 and 65 wt.%, in particular between 30 and 60 wt.%, based on the total composition, at least one flame retardant F.

[0142] Additive

[0143] In addition to the components already mentioned, the polyurethane composition may contain further additives, such as those known to those skilled in the art of two-component polyurethane chemistry. These may be present in only one component or in both.

[0144] In a preferred embodiment, the polyurethane composition is characterized in that the polyurethane composition additionally contains at least one compound selected from the list of solvents, plasticizers, fillers and stabilizers.

[0145] Preferred additives include inorganic and organic fillers FS, such as, in particular, natural, ground or precipitated calcium carbonates (chalk), which may be coated with fatty acids, especially stearic acid, barite (barytes), talcs, quartz flours, quartz sand, dolomites, wollastonites, kaolins, calcined kaolins, mica (potassium aluminum silicate), molecular sieves, silicic acids, industrially produced carbon black, graphite, metal powders such as aluminum, copper, iron, silver or steel, PVC powder or hollow spheres.

[0146] It can be advantageous to use a mixture of different fillers (FS). Combinations of ground calcium carbonates or calcined kaolins and carbon black are most preferred.

[0147] Preferably, the composition according to the invention does not contain any filler FS, apart from any flame-retardant fillers which are read under the flame retardant F.

[0148] The filler content FS in the composition is preferably in the range of 0 to 40 wt.%, in particular 0 to 35 wt.%, especially preferably 0 to 30 wt.%, based on the total composition.

[0149] The filler content FS in the first component A is preferably in the range of 0 to 50 wt.%, more preferably 0 to 40 wt.%, and in particular 0 to 30 wt.%, filler FS, based on component A. The filler content FS in the second component B is preferably in the range of 0 to 50 wt.%, more preferably 0 to 40 wt.%, and in particular 0 to 30 wt.%, filler FS, based on the second component B.

[0150] Other components that can be used include solvents such as polyether glycol (marketed by Arkema under the trade name Ensoline PHP).

[0151] Other ingredients that can be used include, in particular, plasticizers such as castor oil.

[0152] Other additives may include, in particular, extenders, pigments, rheology modifiers such as amorphous silicas, drying agents such as zeolites, adhesion promoters such as organofunctional trialkoxysilanes, stabilizers against oxidation, heat, light and UV radiation, as well as surfactants, especially wetting agents and defoamers.

[0153] Preferred rheology modifiers may include amorphous silicas, in particular highly dispersed silicas from pyrolysis processes, especially fumed silica treated with polysiloxanes (marketed by Evonik under the trade name Aerosil® 202).

[0154] Preferred stabilizers may include primary phenolic antioxidants and heat stabilizers (marketed by BASF under the trade name Irganox 1035) and phenolic benzotriazoles as UV absorbers (marketed by BASF under the trade name Tinuvin 928).

[0155] In a preferred embodiment, the polyurethane composition is characterized in that the first component A is always related to the total composition of component A.

[0156] 10 to 40 wt% polyol P; 1 to 5 wt% diol O;

[0157] 0.1 to 5 wt.% compound T;

[0158] 0.01 to 2.5 wt.% metal catalyst K;

[0159] 15 to 80 wt.% flame retardant F;

[0160] 0 to 8 wt% solvent LM;

[0161] 0 to 10 wt.% plasticizer WM;

[0162] 0 to 40 wt.% filler FS;

[0163] And that the second component B refers to the entire composition of component B.

[0164] 25 to 75 wt.% polyol P;

[0165] 15 to 70 wt% polyisocyanate I;

[0166] 0 to 6% by weight of adhesion promoter HV;

[0167] Contains 0 to 40 wt% filler FS, and may also contain other components.

[0168] The first component A and the second component B are advantageously formulated such that their mixing ratio in parts by volume or parts by weight is in the range of 10:1 to 1:10, preferably 5:1 to 1:5, in particular 2:1 to 1:2.

[0169] In the mixed polyurethane composition, the ratio between the number of isocyanate groups and the number of isocyanate-reactive groups before curing is preferably in the range of 1.2 to 1, more preferably 1.15 to 1.05. However, it is also possible, although usually not preferred, that a substoichiometric proportion of isocyanate groups compared to isocyanate-reactive groups is present.

[0170] The two components, A and B, are manufactured separately and preferably in the absence of moisture. Both components are typically stored in their own containers. Suitable containers for storing each component include, in particular, a drum, a pail, a bag, a bucket, a can, a cartridge, or a tube. Both components are stable for storage, meaning they can be kept for several months up to a year or longer before use without any significant change in their respective properties relevant to their application.

[0171] The two components are stored separately before the composition is mixed and only combined during or immediately before use. They are advantageously contained in packaging consisting of two separate compartments.

[0172] In another aspect, the invention comprises a package consisting of a package with two separate chambers, each containing the first component A and the second component B of the composition, respectively.

[0173] Mixing is typically carried out using static or dynamic mixers. During mixing, it is important to ensure that the two components are mixed as homogeneously as possible. If the two components are not mixed completely, local deviations from the advantageous mixing ratio will occur, which can result in a deterioration of the mechanical properties.

[0174] Upon contact of the first component A with the second component B, curing begins through a chemical reaction. In this process, the hydroxyl groups and any other substances reactive towards isocyanate groups react with the isocyanate groups. Excess isocyanate groups react primarily with moisture. As a result of these reactions, the polyurethane composition cures into a solid material. This process is also known as cross-linking. A further aspect of the invention is therefore a cured polyurethane composition, or articles, obtained from the curing of the polyurethane composition, or the process described in this document. The cured polyurethane composition is characterized by having a flammability classification of VO as measured according to UL94.

[0175] Proceedings

[0176] The invention therefore also relates to a method for bonding a first substrate to a second substrate,

[0177] In a preferred embodiment, the method for bonding a first substrate to a second substrate is characterized in that it comprises the following steps: i) mixing the first and second components of the polyurethane composition according to the invention; ii) applying the mixed polyurethane composition to at least one of the substrate surfaces to be bonded; iii) joining the substrates to be bonded within the pot life; iv) curing the polyurethane composition.

[0178] The invention therefore also relates to a method for filling

[0179] Joints and gaps between two substrates, which includes the steps: i) Mixing the previously described first and second components, ii) Applying the mixed polyurethane composition into the joint or gap, iii) Curing the polyurethane composition.

[0180] In these processes for bonding or filling joints and gaps, suitable substrates are particularly important.

[0181] - Glass, glass ceramics, glass mineral fiber mats;

[0182] - Metals and alloys, such as aluminium, iron, steel and non-ferrous metals, as well as surface-treated metals and alloys, such as galvanised or chromium-plated metals; aluminium alloys such as EN AW-5083, AIMg4.5Mn, especially plasma-treated aluminium, are particularly preferred;

[0183] - coated and painted substrates, such as powder-coated metals or alloys and painted sheets;

[0184] - Plastics such as polyvinyl chloride (rigid and flexible PVC), acrylonitrile butadiene styrene copolymers (ABS), polycarbonate (PC), polyamide (PA), poly(methyl methacrylate) (PMMA), polyesters, epoxy resins, in particular epoxy-based thermosets, polyurethanes (PUR), polyoxymethylene (POM), polyolefins (PO), polyethylene (PE) or polypropylene (PP), ethylene / propylene copolymers (EPM) and ethylene / propylene / diene terpolymers (EPDM), wherein the plastics may preferably be surface-treated by plasma, corona or flame;

[0185] - Fiber-reinforced plastics, such as carbon fiber reinforced plastics (CFRP), glass fiber reinforced plastics (GFRP) and sheet moulding compounds (SMC);

[0186] - Wood, bonded with resins, for example phenolic, melamine or epoxy resins, wood-based materials, resin-textile composites and other so-called polymer composites; as well as

[0187] - Concrete, mortar, bricks, plaster and natural stones such as granite, limestone and sandstone or marble.

[0188] In these processes, one or both substrates are preferably a metal or a glass ceramic or a glass or a glass fiber reinforced plastic or a carbon fiber reinforced plastic or an epoxy-based thermoset.

[0189] The substrates can be pretreated, if necessary, before applying the composition. Such pretreatments include, in particular, physical and / or chemical cleaning processes, as well as the application of an adhesion promoter, an adhesion promoter solution, or a primer.

[0190] In a preferred embodiment, this is a method for bonding a first substrate to a second substrate, characterized in that the substrate is a metal and / or a metal alloy, in particular aluminum. In a further aspect, the invention therefore comprises a method for filling joints and gaps in a substrate, comprising the steps i) mixing the first component and the second component of a two-component polyurethane composition as described above, ii) applying the mixed polyurethane composition to the joint to be bridged between two substrates or to the gap to be filled on the surface of a substrate, iii) curing the polyurethane composition in the joint or gap.

[0191] Suitable substrates include metal, plastic, wood, glass, ceramics, and fiber-reinforced plastics, especially metals and metal alloys and fiber-reinforced plastics. In a further aspect, the invention therefore also comprises a filled article which has been filled according to the method described above.

[0192] The polyurethane composition is further preferably used as a matrix in composite materials. In this context, the polyurethane composition serves as a binder into which fibers or other reinforcing structures are embedded. In a further aspect, the invention therefore encompasses the use of a two-component polyurethane composition as a matrix in composite materials.

[0193] Article

[0194] This article is, in particular, a sandwich element of a lightweight structure, a building, for example a bridge, an industrial good or a consumer good, in particular a window, a rotor blade of a wind turbine, or a means of transport, in particular a vehicle, preferably an automobile, particularly preferably an electric car, also a battery, in particular a battery for a vehicle, a bus, a truck, a rail vehicle or a ship, as well as an aircraft or a helicopter; or an attachment of such an article. A further object of the invention is an article produced by the described bonding methods, in which the polyurethane composition bonds two substrates together.

[0195] The described polyurethane composition is characterized by high strength and elasticity, which remain fairly constant over a wide temperature range from -35 to 85 °C, and by good, largely temperature-independent adhesion properties to metallic substrates. Due to these properties, it is particularly suitable as a structural adhesive for bonding applications subjected to outdoor ambient temperatures.

[0196] Another object of the invention is therefore the use of the described polyurethane composition as a structural adhesive for bonding two substrates.

[0197] use

[0198] The invention also relates to the use of the polyurethane composition.

[0199] Another object of the invention is the use of the polyurethane composition according to the invention as a structural adhesive for bonding two substrates, in particular in automotive applications or as a sealant or as a potting compound.

[0200] The described polyurethane composition can also be used advantageously as a potting compound, in particular as a potting compound for filling gaps and joints, for repair purposes, as a ballast leveling compound or for protecting electronic components.

[0201] The polyurethane composition is further preferably used as a potting compound, in particular as an electrical potting compound. In a further aspect, the invention therefore comprises the use of a two-component polyurethane composition as a potting compound, in particular as an electrical potting compound.

[0202] Examples

[0203] The following are exemplary embodiments intended to further illustrate the described invention. Of course, the invention is not limited to these described embodiments.

[0204] A temperature of 23±1 °C (room temperature) and a relative humidity of 50±5% are referred to as "standard climate" (NC).

[0205] Production of polyurethane compounds

[0206] For each composition, the ingredients listed in Tables 1 and 2, in the specified quantities, were processed into a homogeneous paste using a vacuum dissolver under exclusion of moisture and stored. Similarly, the ingredients listed in Tables 1 and 2 for the second component, B, were processed and stored. Subsequently, the two components were mixed into a homogeneous paste using a SpeedMixer® (DAC 150 FV, Hauschild) for 30 seconds and immediately tested as follows. The volume mixing ratio corresponds to a 1:1 mixture.

[0207] Test methods

[0208] To determine the mechanical properties, the adhesive was formed into a dumbbell shape according to ISO 527, Part 2, 1 B, and stored / cured for 7 days at 23°C and 50% relative humidity. The modulus of elasticity in the range of 0.05 to 0.25% elongation (“Young's modulus”) and the elongation at break of the specimens thus produced were measured according to DIN EN ISO 527 on a Zwick Z020 tensile testing machine at 23°C and 50% relative humidity and a testing speed of 10 mm / min.

[0209] To measure the tensile shear strength and fracture pattern, various test specimens were prepared. The adhesive was applied to an overlapping bonding surface of 16 x 25 mm between a heptane-degreased, E-coated steel sheet (100 mm x 25 mm x 0.8 mm) and an aluminum sheet (EN AW-5083, AIMg4.5Mn, 100 mm x 25 mm x 1.5 mm) in a layer thickness of 1.6 mm, one minute after the mixing time was complete. The test specimens were stored / cured for 24 hours at 23°C, and the tensile shear strength was then determined according to DIN EN 1465. The fracture pattern was evaluated based on the following properties:

[0210] SCF = Substrate-cohesive fracture

[0211] CF = Cohesive Fracture

[0212] AF = Adhesive fracture

[0213] Pot life was measured in a viscometer as the time until the viscosity after mixing the two components reached 500 Pa s. Viscosity was measured on a plate-plate rheometer MCR 101 (Anton Paar) with a plate diameter of 25 mm and a plate spacing of 0.2 mm at a frequency of 0.1 s. _1 and a temperature of 25°C. For this purpose, the two components were first mixed by hand for 30 seconds and then immediately applied to the plates for measurement.

[0214] Substances used

[0215] Table 1: Substances used. Polyurethane composition

[0216] Examples Z1 to Z3 are inventions according to the invention.

[0217] Compositions. In the comparative example Z4 (Ref.), the

[0218] Flame retardant F is replaced in the same quantity with filler FS (chalk). Table 2: Compositions. Material tests

[0219] The results in Table 3 show that the compositions Z1 to Z3 according to the invention exhibit particularly good adhesion to aluminum, as they produce a completely cohesive fracture pattern. In the comparative example Z4 (Ref.), which does not contain flame retardants F, the fracture pattern shows a completely adhesive fracture. This demonstrates that surprisingly, by omitting flame retardants F (and replacing them with a conventional filler) in the composition, a significantly weaker adhesion is achieved. With regard to the other mechanical properties, the compositions Z1 to Z3 according to the invention are superior to the comparative example Z4 (Ref.). Furthermore, Table 3 shows that the pot life can be adjusted by varying the amounts of compound T and metal catalyst K. Table 3: Material tests.

Claims

Patent claims 1. Polyurethane composition consisting of a first component A and a second component B, wherein - the first component A - at least one polyol P; - at least one diol O with an average molecular weight of less than 250 g / mol; - comprises at least one compound T, which has at least one thiol group; and - The second component B - optionally a polyol P; - comprising at least one polyisocyanate I; wherein one of the two components A and B additionally contains at least one metal catalyst K for the reaction of hydroxyl groups and isocyanate groups, which can form thiol complexes with compound T, and wherein the molar ratio of all thiol groups of the at least one compound T to all metal atoms of the metal catalyst K is between 1:1 and 250:1, and wherein the polyurethane composition additionally contains at least 10 wt%, based on the total polyurethane composition, of a flame retardant F.

2. The polyurethane composition according to claim 1, characterized in that the polyol P comprises a medium OH functionality in the range of 2 to 4 and / or a number-average molecular weight M n , determined by gel permeation chromatography, in the range of 250 to 10,000 g / mol and / or has an OH number in the range of 250 to 600 mg KOH / g.

3. The polyurethane composition according to one of claims 1 to 2, characterized in that the polyol P comprises polybutadiene polyols, polycarbonate polyols, polyester polyols, polyether polyols, poly(meth)acrylate polyols or a mixture of these polyols.

4. Polyurethane composition according to one of claims 1 to 3, characterized in that the diol O is a linear aliphatic diol with two primary hydroxyl groups linked via a C2 to C9 carbon chain, in particular selected from the group consisting of 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol and 1,9-nonanediol.

5. Polyurethane composition according to any one of claims 1 to 4, characterized in that the polyisocyanate I is a liquid form at room temperature of 4,4'-, 2,4'- or 2,2'- diphenylmethane diisocyanate and any mixtures of these isomers (MDI) in the form of polymeric MDI or MDI with proportions of oligomers or derivatives, in particular carbodiimides.

6. Polyurethane composition according to one of claims 1 to 5, characterized in that the metal catalyst K comprises a tin(IV) compound and / or a bismuth(III) compound.

7. Polyurethane composition according to one of claims 1 to 6, characterized in that in the entire composition the ratio between the number of isocyanate groups and the number of groups reactive towards isocyanates before curing is in the range of 1.2 to 1.

8. Polyurethane composition according to any one of claims 1 to 7, characterized in that the flame retardant F is solid under standard conditions, wherein standard conditions denote a temperature of 25°C and a pressure of 1013 hPa.

9. Polyurethane composition according to one of claims 1 to 8, characterized in that the flame retardant F comprises an organophosphorus compound, in particular phosphoramidates and / or phosphates, and / or metal hydroxides, in particular aluminium hydroxides.

10. Polyurethane composition according to any one of claims 1 to 9, characterized in that the flame retardant F comprises a combination of aliphatic phosphoramidate, preferably in a range of 5 to 20 wt.%, fine-grained ammonium polyphosphate, preferably in a range of 10 to 30 wt.%, and precipitated aluminum hydroxide, preferably in a range of 20 to 60 wt.%, all based on the first component A.

11. Polyurethane composition according to one of claims 1 to 10, characterized in that the first component A is in each case related to the total composition of component A - 10 to 40 wt% polyol P; - 1 to 5 wt% Diol O; - 0.1 to 5 wt.% compound T; - 0.01 to 2.5 wt.% metal catalyst K; - 15 to 80 wt.% flame retardant F; - 0 to 8 wt% solvent LM; - 0 to 10 wt% plasticizer WM; - 0 to 40 wt.% filler FS; And that the second component B refers to the entire composition of component B. - 25 to 75 wt% polyol P; - 15 to 70 wt% polyisocyanate I; - 0 to 6 wt.% adhesion promoter HV; - Contains 0 to 40 wt% filler FS, and may also contain other components.

12. A method for bonding a first substrate to a second substrate comprises the steps of: i) mixing the first and second components of a polyurethane composition according to any one of claims 1 to 11; ii) applying the mixed polyurethane composition to at least one of the substrate surfaces to be bonded; iii) joining the substrates to be bonded within the pot life; iv) curing the polyurethane composition.

13. The method according to claim 12, characterized in that the substrate is a metal and / or a metal alloy, in particular aluminium.

14. An article produced by the bonding method according to one of claims 12 to 13.

15. Use of a polyurethane composition according to any one of claims 1 to 11 as a structural adhesive for bonding two substrates, particularly in automotive applications, or as a sealant or potting compound.

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