Two-component polyurethane compositions with high hydrophobicity and adjustable pot life

Abstract

The present invention relates to a polyurethane composition comprising a first component A and a second component B. The first component A comprises 30% to 99% by weight, based on component A, of a polyol mixture P, the polyol mixture P comprising 100 parts by weight of at least one hydrophobic polyol P1, 10 to 75 parts by weight of at least one hydrophilic polyol P2, and 0 to 25 parts by weight of at least one diol P3 having two hydroxyl groups bonded via a C2 to C9 carbon chain, and at least one compound T having at least one thiol group; and the second component B comprises at least one polyisocyanate I, wherein at least one of the two components further comprises at least one metal catalyst K for the reaction of hydroxyl groups with isocyanate groups, the metal catalyst being capable of forming a thio complex, and the molar ratio of all thiol groups of the at least one compound T to all metal atoms of the at least one metal catalyst K is in the range of 1:1 to 250:1. Such compositions allow for the full adjustment of the cure time of the hydrophobic polyurethane composition within a specific range, and can achieve long cure times followed by very rapid cure of the composition. The compositions of the present invention are particularly suitable as hydrophobic structural adhesives for bonding two components or as matrices in composite materials.

Description

[Technical Field]

[0001] The present invention relates to the field of two-component (two-part) polyurethane compositions and their use, in particular as adhesives or as matrices in composite materials. [Background technology]

[0002] Two-component polyurethane compositions based on polyols and polyisocyanates have been used for a long time. Two-component polyurethane compositions have the advantage over one-component compositions that they can cure quickly after mixing, and thus can absorb and transmit greater forces in a very short time. When used as structural adhesives or as matrices (binders) in composite materials, these compositions must meet high requirements for strength and adhesion, since they are components of load-bearing structures. In particular, these compositions, when cured, must have good mechanical properties, such as a high modulus of elasticity with low elongation values and high tensile and tensile shear strengths, but at the same time must not be brittle. For example, in industrial production, it is further desirable for such compositions to cure as quickly as possible, thereby reducing processing times.

[0003] To achieve the desired mechanical properties and, in particular, rapid curing, it is advantageous for such compositions to contain a high proportion of isocyanate, present as one of the two components in the form of free or polymer-bound polyisocyanate, which cures to form a polymer network after mixing with the other component containing the polyol. However, high isocyanate content can cause problems. In particular, the use of crosslinking catalysts, which are important for selective and optimal crosslinking and curing, can make such two-part systems uncontrollably fast and have a pot life that is too short for use, for example, as a structural adhesive. For use as a binder in composites, the pot life must also be long enough to allow uniform embedding of fibers in the matrix.

[0004] For the use of two-component polyurethane compositions, it is generally desirable to be able to combine a sufficiently long pot life with subsequent very rapid cure and very rapid strength development. However, this is difficult to achieve with current two-component compositions. Either the pot life is too short for compositions with rapid cure and strength development, or the cure and strength development is slow when dealing with compositions with long pot life.

[0005] Thus, two-component polyurethane compositions have been developed that have a long pot life that can be adjusted within certain limits, allowing the processing of larger components or manufacturing parts, but that cure very quickly after application, for example, within a few hours to a few days, and also exhibit strength and elasticity in the sense of structural adhesion. One such two-component polyurethane composition is disclosed in WO 2019 / 002538 A1. This publication teaches a special catalyst system comprising a metal catalyst and a compound containing a thiol group, which allows an adjustable long pot life and also allows the composition to cure very quickly.

[0006] Similar two-component polyurethane compositions containing such catalyst systems are disclosed in U.S. Patent No. 5,587,448 A. The two-component polyurethane compositions taught therein are mostly based on various polypropylene glycol-based polyether polyols and are particularly suitable as coatings.

[0007] In the case of two-component polyurethane compositions, a wider spectrum of mechanical properties can be achieved, ranging from soft elastic to highly structured properties, by appropriately combining the individual components.

[0008] Furthermore, two-component polyurethane compositions and the aforementioned rapid strength development can be achieved exclusively from hydrophobic raw materials, especially by using polymers containing isocyanate groups, with the added advantage of being based on hydrophobic polyols. This is much less likely with one-component polyurethanes that are cured by atmospheric moisture, because the diffusion of water in hydrophobic compositions is very limited. As a result of their hydrophobicity, adhesives obtained from such two-component compositions generally absorb very little water after curing and exhibit improved aging resistance. Mechanical properties are also often very good. Furthermore, the development of adhesive strength on low-energy surfaces, such as polyolefins or polycarbonates, is significantly improved compared to polyurethanes based on polar units.

[0009] An example of a polyurethane adhesive based on hydrophobic polybutadiene is described in U.S. Pat. No. 4,812,524 A. The adhesive disclosed in U.S. Pat. No. 4,812,524 A is based on a combination of amine-terminated and hydroxyl-terminated polybutadienes, which are reacted with polyisocyanates to give polyurethanes. The adhesive described is believed to be characterized by excellent adhesive properties and strong bonds to steel substrates.

[0010] Another two-component hydrophobic polyurethane adhesive is taught in WO 2017 / 017089 A1. The composition disclosed therein is based on a hydrophobic polybutadiene polyol and a hydrophobic diol selected from polybutadiene diols, polyester diols, polycarbonate diols, and polyether diols having at least 4 carbon atoms in the repeat unit. Mercaptosilanes are also taught, but only as adhesion promoters.

[0011] CN 110 669 469 A also teaches hydrophobic two-component structural polyurethane adhesives based on, for example, polybutadiene polyols and polyester polyols, and again teaches mercaptosilanes, but only as silane crosslinkers.

[0012] WO 2019 / 195045 A1 also teaches hydrophobic two-component polyurethane compositions as adhesives, particularly for polypropylene substrates. These compositions are based on a hydrophobic polyol selected from poly(butylene oxide) polyol, polybutadiene polyol, and acrylate polyol. Dioctyltin dimercaptide catalyst is used in the examples.

[0013] However, such hydrophobic two-component polyurethane compositions containing isocyanate groups and hydrophobic polyol-based polymers have very low compatibility with the special catalyst systems that have the aforementioned adjustable long pot life and rapid cure. It has been found that such hydrophobic two-component polyurethane compositions cannot be easily catalyzed, for example, by the systems taught in WO 2019 / 002538 A1. The effect of rapid cure after the end of the pot life is much weaker than that of hydrophilic polyurethane compositions such as those disclosed in WO 2019 / 002538 A1.

[0014] It would therefore be desirable to have a hydrophobic two-component polyurethane composition that has all the advantages of such hydrophobic compositions described above, but further includes a catalyst system that exhibits a long and controllable pot life followed by very rapid curing. Summary of the Invention [Problem to be solved by the invention]

[0015] It is therefore an object of the present invention to provide a hydrophobic two-component polyurethane composition which cures very quickly to form a mechanically excellent mass suitable as a structural adhesive or as a matrix for composite materials, and at the same time has a sufficiently long pot life which can be adjusted within certain limits, allowing it to be handled without problems. [Means for solving the problem]

[0016] Surprisingly, this object is achieved by the polyurethane composition of the present invention, as claimed in claim 1. It comprises, in a first component, a polyol mixture containing at least one hydrophobic polyol and at least one hydrophilic polyol, optionally including a short-chain diol, and at least one compound having a thiol group, and in a second component, a polyisocyanate. To cure the composition, the composition further comprises a metal catalyst capable of forming a thiocomplex, where the ratio of thiol groups to metal atoms is fixed. Upon curing, the composition exhibits very high strength and good elasticity. After mixing the components, and after a sufficiently long pot life that can be adjusted within certain limits, it cures very quickly, achieving very good mechanical properties within a very short time, for example, from a few hours to a day.

[0017] Further aspects of the invention are the subject of further independent claims. Particularly preferred embodiments of the invention are the subject of the dependent claims. DETAILED DESCRIPTION OF THE INVENTION

[0018] The present invention provides a polyurethane composition comprising a first component A and a second component B, - the first component A comprises: 30% to 99% by weight, based on component A, of a polyol mixture P comprising: 100 parts by weight of at least one hydrophobic polyol P1, - 10 to 75 parts by weight of at least one hydrophilic polyol P2, - 0 to 25 parts by weight of at least one diol P3 having two hydroxyl groups linked via a C2 to C9 carbon chain, and - at least one compound T having at least one thiol group; and the second component B comprises: - at least one polyisocyanate I; one of the two components further comprises at least one metal catalyst K for the reaction of hydroxyl groups capable of forming thio complexes with isocyanate groups, and the molar ratio of the total thiol groups in the at least one compound T to the total metal atoms in the at least one metal catalyst K is 1:1 to 250:1; The present invention relates to a polyurethane composition.

[0019] In this document, the prefix "poly" in the names of substances such as "polyols," "polyisocyanates," "polyethers," or "polyamines" indicates that the respective substance formally contains more than one of the functional groups appearing in the name per molecule.

[0020] The term "polymer" in this document includes, firstly, a population of chemically uniform macromolecules that differ in degree of polymerization, molar mass, and chain length, said population being produced by "poly" reactions (polymerization, polyaddition, polycondensation). Secondly, the term also includes derivatives of such a population of macromolecules resulting from "poly" reactions, i.e., compounds that are obtained by reaction, for example addition or substitution, of functional groups on a given macromolecule, and that may be chemically uniform or chemically heterogeneous. The term also includes so-called prepolymers, i.e., reactive oligomeric initial adducts whose functional groups are involved in the formation of a macromolecule.

[0021] The term "polyurethane polymer" includes all polymers produced by the so-called diisocyanate polyaddition process. This also includes polymers that are substantially or completely free of urethane groups. Examples of polyurethane polymers are polyether polyurethanes, polyester polyurethanes, polyether polyureas, polyureas, polyester polyureas, polyisocyanurates, and polycarbodiimides.

[0022] "Molecular weight" is understood in this document to mean the molar mass (in grams / mole) of a molecule or molecular residue. "Average molecular weight" is the number-average M of a polydisperse mixture of oligomeric or polymeric molecules or molecular residues. n which is typically determined by gel permeation chromatography (GPC) against polystyrene as a standard.

[0023] Weight percentages, abbreviated as wt. %, mean the proportion by mass of a component in a composition based on the total composition, unless otherwise specified. The terms "mass" and "weight" are used interchangeably herein.

[0024] "Primary hydroxyl group" means an OH group bonded to a carbon atom bearing two hydrogens.

[0025] In this document, "pot life" means the time within which the polyurethane composition can be processed after mixing of the two components before the viscosity generated by the crosslinking reaction becomes too high for further processing.

[0026] In this document, the term "strength" refers to the strength of the cured composition, where strength means in particular tensile strength and modulus in the range of elongation of 0.05% to 0.25%, or in the range of 0.5 to 5.0%.

[0027] In this document, "room temperature" means a temperature of 23°C.

[0028] 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 relatively long period of time, typically at least 3 months up to 6 months or more, without its application or use properties, particularly viscosity and crosslinking rate, changing upon storage to an extent relevant to its use.

[0029] All industry standards and regulations referred to in this document relate to the editions in effect on the date of original filing.

[0030] "Average OH functionality" is 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 remaining 50% contain three hydroxyl groups, the resulting average OH functionality is 2.5. Average OH functionality is related to, among other things, the hydroxyl number and the molecular weight M determined by GPC. nIt can be calculated from

[0031] The polyurethane composition of the present invention comprises a first component A and a second component B, which are mixed only when the polyurethane composition is to be applied, and which are stored in separate packaging materials prior to this.

[0032] The first component A is a polyol mixture P of 30% by weight to 99% by weight based on the component A, 100 parts by weight of at least one hydrophobic polyol P1, - 10 to 75 parts by weight of at least one hydrophilic polyol P2, - 0 to 25 parts by weight of at least one diol P3 having two hydroxyl groups linked via a C2 to C9 carbon chain, and at least one compound T having at least one thiol group.

[0033] The first component A therefore initially comprises at least one hydrophobic polyol P1, which is present in the polyol mixture P present in the composition of the invention in a content of between 30% and 90% by weight, based on component A.

[0034] The polyol mixture P preferably has a content in component A of between 40% and 80% by weight, in particular between 45% and 75% by weight, most preferably between 50% and 70% by weight, based on component A.

[0035] The polyol mixture P comprises 100 parts by weight of at least one hydrophobic polyol P1.

[0036] The hydrophobic polyol P1 preferably has an OH functionality in the range from 1.5 to 4 and an average molecular weight in the range from 250 to 15000 g / mol.

[0037] The term "hydrophobic" in relation to polyol P1 is understood to mean that the parent polymer of the polyol is not significantly modified with hydrophilic functional groups, for example, in the form of polar functional groups on the main chain or attached side chains formed from hydrophilic polyethers such as polyethylene glycol and polypropylene glycol, because such modification significantly reduces the hydrophobicity. Therefore, in the context of the present invention, it is preferred when the parent polymer of polyol P1 consists of the aforementioned materials, namely, polybutadiene, polyester, polycarbonate, and polyethers having repeating units with at least 4 carbon atoms. Polyethers having at least 4 carbon atoms in the repeating unit, such as poly(butylene oxide) polyol or poly(tetramethylene glycol), or poly(butylene glycol), are considered hydrophobic polyols.

[0038] Suitable hydrophobic polyols P1 are in particular polybutadiene polyols, hydrophobic polyester polyols, hydrophobic polycarbonate polyols, polyester polyols based on dimer fatty acids, and hydrophobic polyether polyols having repeating units with at least 4 carbon atoms between the two ether oxygens, such as poly(butylene oxide) polyols.

[0039] In a preferred embodiment, the hydrophobic polyol P1 is a polybutadiene polyol, a polyester polyol based on dimer fatty acid, a polytetramethylene oxide diol, or a mixture of the above polyols.

[0040] As hydrophobic polyol P1, polybutadiene polyols having an average molecular weight in the range of 2000 to 10000 g / mol and an average OH functionality in the range of 2.1 to 4 are preferred.

[0041] The average molecular weight of the polybutadiene polyol is preferably in the range of 2000 to 4000 g / mol, particularly in the range of 2500 to 3000 g / mol.

[0042] The average OH functionality of the polybutadiene polyol is preferably in the range of 2.1 to 2.9, in particular in the range of 2.3 to 2.7.

[0043] Such polybutadiene polyols can be obtained by simple processes, have relatively low viscosities and provide good processability of the compositions.

[0044] Suitable polybutadiene polyols can be obtained in particular by polymerization of 1,3-butadiene and allyl alcohol in suitable ratios, or by oxidation of suitable polybutadienes or their hydrogenation products.

[0045] Suitable polybutadiene polyols in particular comprise structural elements of formula (I) and optionally structural elements of formula (II) or (III). [ka]

[0046] One preferred polybutadiene polyol is 40 to 80%, in particular 55% to 65%, of structural elements of formula (I), 0 to 30%, in particular 15% to 25%, of structural elements of formula (II), 0 to 30%, in particular 15% to 25%, of structural elements of formula (III), Includes.

[0047] A particularly suitable polybutadiene polyol is PolyBD® R-45 HTLO or PolyBD® R-45M (both manufactured by Cray Valley).

[0048] Also suitable as polymers P1 are polyhydrocarbon polyols, also called oligohydrocarbonols, such as 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-butadiene or diene mixtures, with vinyl monomers, such as styrene, acrylonitrile, or isobutylene, or polyhydroxy-functional polybutadiene polyols, such as those produced by copolymerization of 1,3-butadiene and allyl alcohol, which may also be hydrogenated.

[0049] Also suitable as polymer P1 are, for example, polyhydroxy-functional acrylonitrile / butadiene copolymers, such as those that can be prepared 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.

[0050] Also suitable are hydrophobic polyols P1 having an average molecular weight in the range of 500 to 5000 g / mol, selected from the group consisting of polybutadiene diols, polyester diols, polycarbonate diols, and polyether diols having repeating units with at least 4 carbon atoms, where the polyether diol having repeating units with at least 4 carbon atoms is preferably polytetramethylene oxide diol.

[0051] The hydrophobic polyol P1 is, in a further preferred embodiment, preferably an aliphatic or cycloaliphatic polyol having an average OH functionality between 2 and 4 and no aromatic components.

[0052] Among these, preference is given to aliphatic or alicyclic polyols, preferably polytetramethylene oxide diol, or polycarbonate diols based on 3-methylpentane-1,5-diol and hexane-1,6-diol, or polyester carbonate diols based on hexane-1,6-diol and ε-caprolactone, or polyester diols based on 3-methylpentane-1,5-diol and adipic acid or sebacic acid.

[0053] One particularly suitable polyester polyol is the condensation product of 3-methylpentane-1,5-diol and adipic acid or sebacic acid. Polyester polyols of this type are available, for example, from Kuraray under the trade name Kuraray® P-2010.

[0054] One particularly suitable aliphatic polycarbonate polyol based on 3-methylpentane-1,5-diol and hexane-1,6-diol is available, for example, from Kuraray under the trade name Kuraray® C-2050.

[0055] One particularly suitable aliphatic polyestercarbonate polyol based on hexane-1,6-diol and ε-caprolactone is available under the trade name Desmophen® C 1200 from Bayer Material Science.

[0056] Particularly preferred as hydrophobic polyols P1 are polyester polyols based on dimer fatty acids obtained from oily (renewable) raw materials.

[0057] Polyester polyols based on dimer fatty acids of this type are preferably liquid at room temperature, and in particular have an OH number in the range of 28 to 120 mg KOH / g.

[0058] Such polyester polyols based on dimeric fatty acids have an average molecular weight in the range of 950 to 4000 g / mol, are usually predominantly linear, and have an average OH functionality of about 2, in particular between 2 and 2.5.

[0059] The dimer fatty acid based polyester polyols are preferably amorphous.

[0060] Dimer fatty acid-based polyester diols suitable as polymers P1 are obtainable in particular by esterification of at least one dimer fatty alcohol, such as ethylene glycol or butanediol, and / or a dicarboxylic acid, such as adipic acid, with at least one dimer fatty acid and / or diol, in a stoichiometry such that the product is amorphous, liquid at room temperature, and has an OH number in the range of 28 to 120 mg KOH / g.

[0061] The polyester polyol based on dimer fatty acid preferably has a content of carbon atoms from renewable resources in the range of 50 to 100%, preferably 60 to 95%, and in particular 70 to 90%, based on the total carbon content, in accordance with ASTM D6866. Such polyester polyols are amorphous and hydrophobic and have particularly good compatibility in polyurethane adhesives.

[0062] The polyester polyols based on dimeric fatty acids used as polymer P1 preferably have an OH number in the range of 34 to 120 mg KOH / g, in particular 52 to 60 mg KOH / g. Such polyester polyols based on dimeric fatty acids have an average molecular weight in the range of 950 to 3300 g / mol, in particular 1900 to 2200 g / mol. Such polymers allow polyurethane compositions to have a particularly attractive combination of good developability, good adhesive properties, and high strength.

[0063] Particularly suitable are commercially available polyester polyols based on amorphous dimer fatty acids, in particular those available under the trade name Priplast® such as grades Priplast® 1837, 1838, 3187, 3196, 3197, 3199 or 3238 (Croda). Preferred among these is Priplast® 1838. Also suitable are VASF's Solvermol® grades, in particular Solvermol® RC 1005 and Solvermol® 805.

[0064] The hydrophobic polyol P1 in all embodiments preferably has an average molecular weight in the range of 400 to 3500 g / mol, in particular 500 to 3250 g / mol, more preferably 750 to 3000 g / mol, most preferably 1000 to 3000 g / mol.

[0065] The hydrophobic polyol P1 in all embodiments preferably has an average OH functionality in the range from 2 to 4, in particular from 2 to 3.5, more preferably from 2 to 3, most preferably from 2 to 2.5.

[0066] The hydrophobic polyol P1 in all embodiments has a hydroxyl number in the range from 45 to 600 mg KOH / g, in particular from 50 to 500 mg KOH / g, more preferably from 50 to 250 mg KOH / g, most preferably from 50 to 200 mg KOH / g.

[0067] The first component A further comprises at least one hydrophilic polyol P2, which is present in the polyol mixture P.

[0068] The polyol mixture P comprises 10 to 75 parts by weight of at least one hydrophilic polyol P2.

[0069] If the amount of hydrophilic polyol P2 per 100 parts by weight of hydrophobic polymer P1 is less than 10 parts by weight, the long pot life and subsequent rapid curing obtained according to the invention can no longer be fully realized.

[0070] Conversely, if the amount of hydrophilic polyol P2 per 100 parts by weight of hydrophobic polymer P1 exceeds 75 parts by weight, the hydrophobicity of the overall composition can no longer be sufficiently adjusted.

[0071] Generally, the higher the proportion of hydrophilic polyol P2, the more rapidly the effect of the present invention, i.e., the curing after the end of the pot life, tends to proceed. On the other hand, the lower the proportion of hydrophilic polyol P2, the more improved the practical hydrophobic properties (e.g., lower water absorption, improved aging resistance, better adhesion to low-energy substrates) and the more improved the mechanical properties. Therefore, depending on the desired field of use and the related desired properties, the ratio of polyols P1 and P2 can be adjusted as needed within certain limits. Furthermore, the above properties can also be influenced by further components in the composition, such as fillers and diol P3 described below, which means that there are further options for influencing the properties of the composition by formulation means.

[0072] Suitable hydrophilic polyols P2 are in principle all common hydrophilic polyols used for the preparation of polyurethane polymers that can be used in conventional one-component (single-liquid) polyurethane compositions that cure with atmospheric moisture. Particularly suitable are hydrophilic polyether polyols, hydrophilic polyester polyols, hydrophilic poly(meth)acrylate polyols, and hydrophilic polycarbonate polyols, as well as mixtures of the aforementioned polyols.

[0073] Suitable polyether polyols, also called polyoxyalkylene polyols or oligoetherols, as polymers P2 are in particular the polymerization products of ethylene oxide, 1,2-propylene oxide, oxetane, or mixtures thereof, optionally with initiator molecules having two or more active hydrogen atoms, such as water, ammonia, or compounds having several OH or NH groups, such as ethane-1,2-diol, propane-1,2-diol and -1,3-diol, neopentyl glycol, diethylene glycol, triethylene glycol, The polymerization products are those prepared using glycol, isomeric dipropylene glycol and tripropylene glycol, isomeric butanediol, pentanediol, hexanediol, heptanediol, octanediol, nonanediol, decanediol, undecanediol, cyclohexane-1,3-dimethanol and -1,4-dimethanol, bisphenol A, hydrogenated bisphenol A, 1,1,1-trimethylolethane, 1,1,1-trimethylolpropane, glycerol, aniline, and mixtures of the above compounds. For example, polyoxyalkylene polyols with low unsaturation (measured in accordance with ASTM D-2849-69 and expressed in milliequivalents of unsaturation per gram of polyol (mEq / g)) prepared using a so-called double metal cyanide complex catalyst (DMC catalyst) can be used, or polyoxyalkylene polyols with relatively high unsaturation prepared using an anionic catalyst such as NaOH, KOH, CsOH, or an alkali metal alkoxide.

[0074] Particularly suitable as polyols P2 are polyoxyethylene polyols and polyoxypropylene polyols, in particular polyoxyethylene diols, polyoxypropylene diols, polyoxyethylene triols, and polyoxypropylene triols.

[0075] Particularly suitable as polyols P2 are polyoxyalkylene diols or polyoxyalkylene triols having a degree of unsaturation of less than 0.02 mEq / g and a molecular weight in the range of 1000 to 15000 g / mol, for example polyoxyethylene diols, polyoxyethylene triols, polyoxypropylene diols and polyoxypropylene triols having a molecular weight of 400 to 15000 g / mol.

[0076] Likewise, particularly suitable polyols P2 are so-called ethylene oxide-terminated (EO end-capped) polyoxypropylene polyols. These are special polyoxypropylene polyoxyethylene polyols, obtained, for example, when pure polyoxypropylene polyols, especially polyoxypropylene diols and triols, are further alkoxylated with ethylene oxide after the polypropoxylation reaction is complete, thereby carrying primary hydroxyl groups. In this case, polyoxypropylene polyoxyethylene diols and polyoxypropylene polyoxyethylene triols are preferred.

[0077] Suitable polyether-based polymers P2 of this type are available, for example, from Covestro under the trade names Acclaim® and Desmophen®, in particular Acclaim® 4200, Desmophen® 5034, Desmophen® 1381 BT, and Desmophen® 28HS98, from Dow under the trade name Voranol®, in particular Voranol® EP 1900 and Voranol® CP 4755, and from Arkema under the trade name Dianol®, in particular Dianol® 3130 HP.

[0078] Also suitable are styrene-acrylonitrile graft polyether polyols, such as those commercially available under the trade name Lupranol® from Elastogran GmbH, Germany.

[0079] Suitable hydrophilic polyester polyols are, in particular, polyesters having at least two hydroxyl groups and prepared by known methods, in particular by polycondensation of hydroxycarboxylic acids or of aliphatic and / or aromatic polycarboxylic acids with dihydric or polyhydric alcohols.

[0080] Particularly suitable are polyester polyols prepared from dihydric to trihydric alcohols, such as ethane-1,2-diol, diethylene glycol, propane-1,2-diol, dipropylene glycol, or mixtures of the aforementioned alcohols, and 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 formed from lactones, such as ε-caprolactone.

[0081] Particularly suitable are hydrophilic polyester diols, in particular those prepared from adipic acid, phthalic acid, isophthalic acid, and terephthalic acid as dicarboxylic acids, or from lactones such as ε-caprolactone, and from ethylene glycol, diethylene glycol, neopentyl glycol, butane-1,4-diol, hexane-1,6-diol, and cyclohexane-1,4-dimethanol as dihydric alcohols.

[0082] Examples of suitable hydrophilic polyester polyols are those available from Kuraray under the Kuraray® trade name, particularly Kuraray® F-510, and from King Industries under the K-Flex® trade name, particularly K-Flex® 188.

[0083] Suitable hydrophilic polycarbonate polyols include those obtainable by reacting the aforementioned alcohols, which are also used to form polyester polyols, with dialkyl carbonates, such as dimethyl carbonate, diaryl carbonates, such as diphenyl carbonate, or phosgene.Polycarbonates obtainable by copolymerizing CO2 with epoxides, such as ethylene oxide and propylene oxide, are also suitable.Polycarbonate diols, especially amorphous polycarbonate diols, are particularly suitable.

[0084] Further suitable polyols are hydrophilic poly(meth)acrylate polyols.

[0085] Particularly suitable polyols P2 are hydrophilic polyester polyols, particularly preferably hydrophilic polyether polyols, in particular polyoxyethylene polyols, polyoxypropylene polyols and polyoxypropylene polyoxyethylene polyols, preferably polyoxyethylene diols, polyoxypropylene diols, polyoxyethylene triols, polyoxypropylene triols, polyoxypropylene polyoxyethylene diols and polyoxypropylene polyoxyethylene triols.

[0086] Most preferably, the hydrophilic polyol P2 is a polyether polyol, in particular a polyether polyol having an average OH functionality of at least 2.5 and preferably having propylene glycol repeat units in the polymer backbone.

[0087] The hydrophilic polyol P2 in all embodiments preferably has an average molecular weight in the range of 400 to 6000 g / mol, in particular 450 to 5500 g / mol, more preferably 500 to 5000 g / mol, most preferably 550 to 5000 g / mol.

[0088] The hydrophilic polyol P2 in all embodiments preferably has an average OH functionality in the range of 2 to 4, in particular 2 to 3.5, more preferably 2 to 3.

[0089] The hydrophilic polyol P2 in all embodiments has a hydroxyl number in the range of 20 to 500 mg KOH / g, in particular 25 to 400 mg KOH / g, more preferably 25 to 250 mg KOH / g.

[0090] The first component A preferably further comprises at least one diol P3 having two hydroxyl groups linked via a C2-C9 carbon chain, which is present in the polyol mixture P.

[0091] The polyol mixture P comprises 0 to 25 parts by weight of at least one diol P3 having two hydroxyl groups linked via a C2 to C9 carbon chain.

[0092] To be effective according to the invention, it is not necessary for a diol P3 to be present in the polyol mixture P. However, the presence of such a diol P3 can be advantageous, especially for the mechanical properties of the polyurethane composition according to the invention.

[0093] Thus, preferred embodiments of the composition of the invention preferably comprise between 5 and 25 parts by weight, in particular between 10 and 20 parts by weight, of diol P3 per 100 parts by weight of hydrophobic polymer P1.

[0094] Suitable diols P3 are linear or branched alkylenediols having two primary or secondary hydroxyl groups, alkylenediols having one primary and one secondary hydroxyl group, and cycloaliphatic diols.

[0095] The diol P3 is preferably a linear aliphatic diol having two primary hydroxyl groups linked via a C4-C9 carbon chain. Such diols have the advantage that polyurethanes with particularly high moduli are obtained, for example in the low elongation range between 0 and 5%, which is particularly advantageous for structural adhesives.

[0096] In particular, diol P3 is ethylene glycol, propane-1,3-diol, butane-1,4-diol, pentane-1,5-diol, hexane-1,6-diol, heptane-1,7-diol, octane-1,8-diol, nonane-1,9-diol, butane-1,3-diol, butane-2,3-diol, 2-methylpropane-1,3-diol, pentane-1,2-diol, pentane-2,4-diol, 2-methylbutane-1,4-diol, 2,2-dimethylpropane-1,3-diol (neopentylglycerol), ethanol), hexane-1,2-diol, butane-1,4-diol, 3-methylpentane-1,5-diol, octane-1,2-diol, octane-3,6-diol, 2-ethylhexane-1,3-diol, 2,2,4-trimethylpentane-1,3-diol, 2-butyl-2-ethylpropane-1,3-diol, 2,7-dimethyloctane-3,6-diol, cyclohexane-1,4-diol, cyclohexane-1,3-dimethanol, and cyclohexane-1,4-dimethanol.

[0097] The diol P3 is particularly preferably selected from the group consisting of butane-1,4-diol, pentane-1,5-diol, hexane-1,6-diol, heptane-1,7-diol, octane-1,8-diol and nonane-1,9-diol.

[0098] Diol P3 is most preferably selected from the group consisting of butane-1,4-diol, pentane-1,5-diol, hexane-1,6-diol, and nonane-1,9-diol, which are readily commercially available and which, when cured, give polyurethanes with particularly high moduli at low elongations.

[0099] In addition to the polyols P1 and P2 and diols P3 described above, it is possible to include small amounts of other low molecular weight dihydric or polyhydric alcohols, such as diethylene glycol, triethylene glycol, isomeric dipropylene glycol and tripropylene glycol, isomeric decanediol and undecanediol, hydrogenated bisphenol A, dimeric fatty alcohols, 1,1,1-trimethylolethane, 1,1,1-trimethylolpropane, glycerol, pentaerythritol, sugar alcohols such as xylitol, sorbitol, or mannitol, sugars such as sucrose, other higher polyhydric alcohols, low molecular weight alkoxylation products of the above dihydric and polyhydric alcohols, and mixtures of the above alcohols. Furthermore, polyols containing other heteroatoms, such as methyldiethanolamine or thioglycol, may also be present.

[0100] The first component A further comprises at least one compound T having at least one thiol group. Suitable are any compounds having at least one thiol or mercapto group that can be incorporated into the compositions of the present invention. In this specification, a thiol group is understood to mean an -SH group bonded to an organic group, for example an aliphatic, alicyclic, or aromatic carbon group.

[0101] Preferred are compounds having 1 to 6, particularly 1 to 4, and most preferably 1 or 2 thiol groups. Compounds having thiol groups have the advantage that they do not form complexes with the metal catalyst K which tend to be insufficiently soluble, and the pot life can be adjusted particularly precisely. Compounds having two thiol groups have the advantage that the mechanical properties of the composition when cured are improved.

[0102] Examples of suitable compounds T having a thiol group are 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropane-1,2-diol, 2-mercaptotoluimidazole, or 2-mercaptobenzothiazole.

[0103] Examples of suitable compounds T having two or more thiol groups are ethylene glycol di(3-mercaptopropionate), ethylene glycol dimercaptoacetate, dipentaerythritol hexa(3-mercaptopropionate), 2,3-dimercapto-1,3,4-thiadiazole, or pentaerythritol tetrakis(3-mercaptopropionate).

[0104] Compound T is preferably selected from the group consisting of ethylene glycol di(3-mercaptopropionate), ethylene glycol dimercaptoacetate, dipentaerythritol hexa(3-mercaptopropionate), and 3-mercaptopropyltrimethoxysilane.

[0105] The molar ratio of all thiol groups in at least one compound T to all metal atoms in at least one metal catalyst K (total thiol groups in at least one compound T:total metal atoms in at least one metal catalyst K) should be between 1:1 and 250:1. It is preferably between 2:1 and 150:1, in particular between 5:1 and 100:1. This quantitative ratio allows the pot life to be adjusted within the limits inherent in a particular composition, for example, due to the catalyst content, the reactivity of the isocyanates present, and their amount. The lower limit of the pot life is the pot life obtained for a particular composition when a defined amount of catalyst is used without the addition of compound T. In many situations suitable for use according to the invention as a structural adhesive or composite matrix, in the presence of a catalyst but without compound T, no actual pot life is realized at all, as a result of the large number of isocyanate groups, and the composition begins to cure almost immediately after mixing the two components.

[0106] Therefore, the upper limit of the adjustable pot life is the pot life achieved by the uncatalyzed isocyanate-hydroxyl reaction when no catalyst is used. Even without a catalyst, this reaction will begin at some point after the two components are mixed. However, the uncatalyzed reaction will proceed more slowly and the development of mechanical properties in the cured material will be poorer.

[0107] An important advantage realized by the two-component polyurethane composition of the present invention is that it is a system that cures and develops strength very quickly, while at the same time having a sufficiently long pot life that allows for easy processing. This means, for example, that even relatively large substrates can be structurally bonded, which may be exposed to mechanical stress only a short time after application of the adhesive. This significantly reduces processing time, for example, in industrial production. A further advantage of the polyurethane composition of the present invention is the aforementioned adjustable pot life. This is particularly advantageous in automated application, for example, as it allows the pot life to be tailored to the desired application, further optimizing processing time in industrial production.

[0108] The amount of compound T in the first component A is preferably in the range of 0.1% to 5% by weight, preferably 0.2% to 2.5% by weight, in particular 0.25% to 1.0% by weight, based on component A.

[0109] The amount of compound T based on the total polyurethane composition is preferably in the range of 0.04% to 2.0% by weight, preferably 0.08% to 1.0% by weight, in particular 0.1% to 0.4% by weight, based on the total polyurethane composition.

[0110] The second component B primarily comprises at least one polyisocyanate I.

[0111] The polyisocyanate I is preferably present in a large amount, which is highly advantageous for the development of mechanical properties that are sufficiently good for use as a structural adhesive or matrix for composite materials.

[0112] The second component B preferably comprises sufficient polyisocyanate I so that there are at least 5% by weight, especially at least 6% by weight, preferably at least 7.5% by weight, of isocyanate groups, based on the total polyurethane composition.

[0113] The polyisocyanates I used to prepare the polyurethane polymers in the compositions of the invention can be any commercially available polyisocyanates, especially diisocyanates, suitable for the preparation of polyurethanes.

[0114] Suitable polyisocyanates are in particular monomeric di- or triisocyanates, as well as oligomers, polymers and derivatives of monomeric di- or triisocyanates, and any desired mixtures thereof.

[0115] Suitable aromatic monomeric di- or triisocyanates are in particular tolylene 2,4- and 2,6-diisocyanate and any desired mixtures of these isomers (TDI), diphenylmethane 4,4'-, 2,4'-, and 2,2'-diisocyanate and any desired mixtures of these isomers (MDI), mixtures of MDI and MDI homologues (polymeric MDI or PMDI), 1,3- and 1,4-phenylene diisocyanates. nate, 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.

[0116] Suitable aliphatic monomeric di- or triisocyanates are, in particular, tetramethylene 1,4-diisocyanate, 2-methylpentamethylene 1,5-diisocyanate, hexamethylene 1,6-diisocyanate (HDI), 2,2,4- and 2,4,4-trimethylhexamethylene 1,6-diisocyanate (TMDI), decamethylene 1,10-diisocyanate, dodecamethylene 1,12-diisocyanate, lysine diisocyanate and lysine ester diisocyanate. , cyclohexane 1,3- and 1,4-diisocyanate, 1-methyl-2,4-diisocyanatocyclohexane and -2,6-diisocyanatocyclohexane and any desired mixtures of these isomers (HTDI or H6TDI), 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (=isophorone diisocyanate or IPDI), perhydrodiphenylmethane 2,4'- and 4,4'-diisocyanate (HMDI or H 12 MDI), 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-tetramethylxylylene 1,3- and 1,4-diisocyanate (m- and p-TMXDI), bis(1-isocyanato-1-methylethyl)naphthalene, dimeric and trimeric fatty acid isocyanates such as 3,6-bis(9-isocyanatononyl)-4,5-di-(1-heptenyl)cyclohexene (dimethyl diisocyanate), and α,α,α',α',α'',α''-hexamethyl-1,3,5-mesitylene triisocyanate.

[0117] Among these, MDI, TDI, HDI, and IPDI are preferred.

[0118] Suitable oligomers, polymers, and derivatives of the monomeric di- and triisocyanates mentioned are, in particular, those derived from MDI, TDI, HDI, and IPDI. Particularly suitable among these are commercially available grades, in particular HDI biurets, such as Desmodur® N 100 and N 3200 (manufactured by Covestro), Tolonate® HDB and HDB-LV (manufactured by Vencorex), and Duranate® 24A-100 (manufactured by Asahi Kasei); HDI isocyanurates, such as Desmodur® N 3300, N 3600, and N 3790 BA (all manufactured by Covestro), Tolonate® HDT, HDT-LV, and HDT-LV2 (manufactured by Vencorex), Duranate® TPA-100 and THA-100 (manufactured by Asahi Kasei), and Coronate® HX (manufactured by Nippon Polyurethane); HDI uretdiones, such as Desmodur® N 3400 (Covestro); HDI iminooxadiazinediones, such as Desmodur® XP 2410 (Covestro); HDI allophanates, such as Desmodur® VP LS 2102 (Covestro); IPDI isocyanurates, either in solution, such as Desmodur® Z 4470 (Covestro), or in solid form, such as Vestanat® T1890 / 100 (Evonik); TDI oligomers, such as Desmodur® IL (Covestro); and mixed isocyanurates based on TDI / HDI, such as Desmodur® HL (Covestro).Forms of MDI that are liquid at room temperature (so-called "modified MDI"), which are mixtures of MDI and MDI derivatives, such as in particular MDI carbodiimides or MDI uretonimines or MDI urethanes, and are known under the trade names Desmodur® CD, Desmodur® PF, Desmodur® PC (all from Covestro) or Isonate® M 143 (from Dow), as well 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 Lupranate® M 10 Also particularly suitable are mixtures of MDI and MDI homologues (polymeric MDI or PMDI), available under trade names such as BASF®. The oligomeric polyisocyanates described above are in fact typically mixtures of substances with different degrees of oligomerization and / or chemical structures. They preferably have an average NCO functionality of 2.1 to 4.0.

[0119] The polyisocyanate is preferably selected from the group consisting of MDI, TDI, HDI, and IPDI, as well as oligomers, polymers, and derivatives of the mentioned isocyanates, and mixtures thereof.

[0120] The polyisocyanate preferably contains isocyanurate groups, iminooxadiazinedione groups, uretdione groups, biuret groups, allophanate groups, carbodiimide groups, uretonimine groups, or oxadiazinetrione groups.

[0121] Particularly preferred polyisocyanates are MDI forms that are liquid at room temperature. These are in particular so-called polymeric MDI and MDI containing a certain proportion of oligomers or their derivatives. The content of MDI (=diphenylmethane 4,4'-, 2,4'- or 2,2'-diisocyanate, and any desired mixtures of these isomers) in such liquid MDI forms is in particular 50% to 95% by weight, in particular 60% to 90% by weight.

[0122] Particularly preferred as polyisocyanates are polymeric MDI and MDI grades which are liquid at room temperature and contain a proportion of MDI carbodiimide or an adduct thereof.

[0123] These polyisocyanates provide particularly good processing properties and particularly high strengths.

[0124] The polyisocyanate of the second component B can contain a proportion of a polyurethane polymer having isocyanate groups. Either the second component can contain a separately produced polyurethane polymer having isocyanate groups, or the polyisocyanate is mixed with at least one polyol, in particular a polyether polyol, so that the isocyanate groups are present in stoichiometric excess relative to the OH groups.

[0125] In the second component B of the composition of the present invention, the polyisocyanate I is preferably present in an amount of 25% to 100% by weight, in particular 30% to 90% by weight, more preferably 40% to 75% by weight, based on the second component B.

[0126] The first component A and / or the second component B further comprise at least one metal catalyst K for the reaction of hydroxyl groups capable of forming thio complexes with isocyanate groups. Suitable metal catalysts K are, for example, any metal catalysts which can be used as crosslinking catalysts in polyurethane chemistry and which are simultaneously capable of forming thio complexes with thiols in the presence thereof.

[0127] The metal catalyst K is preferably present only in the first component A. This has the advantage of achieving better storage stability.

[0128] In this embodiment, the amount of metal catalyst K in the first component A is preferably in the range of 0.05% to 2.5% by weight, preferably 0.1% to 2.0% by weight, in particular 0.2% to 1.5% by weight, and more preferably 0.25% to 1.0% by weight, based on the first component A.

[0129] When a catalyst is present in a second component B, the same preferred amount ranges as above apply, but with component B as the reference.

[0130] The amount of metal catalyst K based on the total polyurethane composition is preferably in the range of 0.02% to 1.0% by weight, preferably 0.025% to 0.8% by weight, particularly 0.08% to 0.6% by weight, more preferably 0.1% to 0.5% by weight, based on the total polyurethane composition.

[0131] Examples of suitable metal catalysts are compounds of bismuth, zinc, tin, or zirconium, such as complexes and salts of these metals.

[0132] The metal catalyst K preferably comprises a bismuth compound, in particular a bismuth(III) compound. In addition to the desirable properties of a catalyst capable of forming a thio complex, bismuth compounds have the advantage of low acute toxicity.

[0133] Several conventional bismuth catalysts can be used as the bismuth compound, examples being bismuth carboxylates such as bismuth acetate, bismuth oleate, bismuth octoate, or bismuth neodecanoate, bismuth nitrate, bismuth halides such as bromides, chlorides, or iodides, bismuth sulfide, bismuth basic carboxylates such as bismuth neodecanoate, bismuth subgallate, or bismuth subsalicylate, and mixtures thereof.

[0134] In a preferred embodiment, the metal catalyst K is a bismuth(III) complex containing at least one 8-hydroxyquinoline-based ligand. Such a complex is described in EP 1 551 895. It is preferably a bismuth(III) carboxylate containing one molar equivalent of the 8-hydroxyquinoline ligand.

[0135] In a further preferred embodiment, the metal catalyst K is a bismuth(III) complex containing at least one 1,3-ketoamide-based ligand. Such complexes are described in EP 2791153. They are preferably bismuth(III) carboxylates containing 1 to 3 molar equivalents of the 1,3-ketoamide ligand.

[0136] In addition to the components already described, the polyurethane composition may contain additional components known to those skilled in the art of two-component (two-part) polyurethane chemistry, which may be present in only one component or in both components.

[0137] Preferred further constituents are inorganic or organic fillers F, for example in particular natural, ground or precipitated calcium carbonate, optionally coated with fatty acids, in particular stearic acid, barite (baryte), talc, quartz flour, silica sand, dolomite, wollastonite, kaolin, calcined kaolin, mica (potassium aluminum silicate), molecular sieves, aluminum oxide, aluminum hydroxide, magnesium hydroxide, silica, such as pyrogenically obtained finely divided silica, industrially produced carbon black, graphite, metal powders, such as aluminum, copper, iron, silver or steel, PVC powder or hollow spheres, and also flame-retardant fillers, such as hydroxides or hydrates, in particular aluminum hydroxide or hydrate, preferably aluminum hydroxide.

[0138] Preferably, the composition of the present invention comprises at least one filler F in the first component A, in the second component B, or in both components.

[0139] The addition of filler F is advantageous in that it increases the strength of the cured polyurethane composition.

[0140] The polyurethane composition preferably contains at least one filler F selected from the group consisting of calcium carbonate, carbon black, kaolin, baryte, talc, quartz powder, dolomite, wollastonite, kaolin, calcined kaolin, and mica. Particularly preferred fillers F are ground calcium carbonate, calcined kaolin, and carbon black.

[0141] It may be advantageous to use a mixture of different fillers, with ground calcium carbonate or calcined kaolin in combination with carbon black being most preferred.

[0142] The content of filler F in the composition is preferably within a range of 5 to 50% by weight, particularly 10 to 40% by weight, and more preferably 15 to 35% by weight, based on the total composition.

[0143] The content of filler F in the first component A is preferably in the range of 10% to 60% by weight, more preferably 15% to 50% by weight, particularly 20% to 45% by weight, based on component A.

[0144] The content of filler F in the second component B is preferably in the range of 0% to 60% by weight, preferably in the range of 10% to 50% by weight, and particularly 10% to 45% by weight, based on component B.

[0145] Further components may also be present, in particular solvents, plasticizers and / or extenders, pigments, rheology modifiers such as amorphous silica, in particular zeolites, adhesion promoters such as organofunctional trialkoxysilanes, stabilizers against oxidation, heat, light and UV radiation, flame retardants, and surface-active substances such as wetting agents and defoamers, in particular.

[0146] The polyurethane composition preferably contains less than 0.5 wt. %, especially less than 0.1 wt. %, of a carboxylic acid, based on the total composition, excluding any carboxylate ligands introduced via a metal catalyst.

[0147] One preferred polyurethane composition comprises a first component A, which, based on component A, comprises: - 30% to 80% by weight, preferably 40% to 75% by weight, in particular 50% to 70% by weight, of a polyol mixture P, - 0.1% to 5% by weight, preferably 0.2% to 2.5% by weight, in particular 0.25% to 1.0% by weight, of a compound T having at least one thiol group, - 0.05% to 2.5% by weight, preferably 0.1% to 2.0% by weight, in particular 0.2% to 1.5% by weight, more preferably 0.25% to 1.0% by weight of a metal catalyst K, - 10% to 60% by weight, preferably 15% to 50% by weight, in particular 20% to 45% by weight, of filler F, optional further components; The first component A comprises:

[0148] The same or another preferred polyurethane composition may comprise a second component B, which, based on component B, comprises: - 25% to 100% by weight, preferably 30% to 75% by weight, in particular 40% to 60% by weight, of polyisocyanates I, - 0% to 60% by weight, preferably 10% to 50% by weight, in particular 20% to 40% by weight of a polyol, preferably a hydrophilic polyol P2, - 0% to 60% by weight, preferably 10% to 50% by weight, in particular 10% to 45% by weight, of filler F, optional further components; The second component B comprises:

[0149] It is advantageous if the first component A and the second component B are blended in a mixing ratio in parts by volume or parts by weight within the range of 10:1 to 1:10, preferably 5:1 to 1:5, and particularly 2:1 to 1:2.

[0150] The ratio between the number of isocyanate groups and the number of isocyanate-reactive groups in the mixed polyurethane composition before curing is preferably in the range of approximately 1.2 to 1, preferably 1.15 to 1.05. However, although not usually preferred, it is possible for the ratio of isocyanate groups to isocyanate-reactive groups to be substoichiometric.

[0151] The two components A and B are prepared separately, preferably with the exclusion of moisture. These two components are typically stored in separate containers. The additional components of the polyurethane composition can be present as components of the first or second component, with the additional component reactive with isocyanate groups preferably being a component of the first component. Suitable containers for storing each component are, in particular, drums, tin cans, bags, buckets, cans, cartridges, or tubes. Both components are storage-stable, meaning that they can be stored for several months to a year or more before use without their properties changing to a degree suitable for use.

[0152] The two components are kept separate until the composition is mixed and are mixed together only at or shortly before use, and are advantageously present in a packaging material consisting of two separate chambers.

[0153] In a further aspect, the present invention comprises a pack consisting of a packaging material having two separate chambers containing a first component A and a second component B of the composition, respectively.

[0154] Mixing is typically carried out by a static mixer or by a dynamic mixer. During mixing, care must be taken to ensure that the two components are mixed as uniformly as possible. If the two components are not mixed completely, local deviations from the favorable mixing ratio may occur, which may cause a decrease in mechanical properties.

[0155] When the first component, A, comes into contact with the second component, B, curing begins through a chemical reaction. This involves the reaction of the isocyanate groups with hydroxyl groups and any other substances present that are reactive towards the isocyanate groups. Excess isocyanate groups react primarily with moisture. As a result of these reactions, the polyurethane composition cures to form a solid material. This process is also known as crosslinking.

[0156] Thus, the present invention further provides a cured polyurethane composition obtainable by curing the polyurethane composition described herein.

[0157] The described two-component polyurethane compositions can be advantageously used as structural adhesives, potting compounds, or matrices in composite materials.

[0158] Accordingly, the present invention also relates to a method of adhesively bonding a first substrate to a second substrate, comprising the steps of: - mixing said first and second components; - applying the mixed polyurethane composition to at least one of the substrate surfaces to be bonded; - joining the substrates to be bonded within the pot life; - Curing the polyurethane composition.

[0159] The two substrates can be made of the same material or different materials.

[0160] The present invention therefore also relates to a method for filling joints and gaps between two substrates, comprising the steps of: - mixing said first and second components; - applying (spraying) the mixed polyurethane composition to the joint or gap; - Curing the polyurethane composition.

[0161] In these methods for adhesive bonding or for filling joints and gaps, suitable substrates are in particular: - Glass, glass-ceramic and glass-mineral fiber mats; - metals and alloys, such as aluminium, iron, steel and non-ferrous metals, as well as surface-finished metals and alloys, such as galvanised or chrome-plated metals; - Coated and painted substrates, such as powder-coated metals or alloys and painted metal sheets; 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), where the plastics may be surface-treated, preferably by plasma, corona or flame; - Fiber reinforced plastics, such as carbon fiber reinforced plastics (CFRP), glass fiber reinforced plastics (GFRP), and sheet molding compounds (SMC); - wood, wood-based materials bonded with resins, such as phenolic, melamine or epoxy resins, resin-fabric composites and so-called polymer composites; and - Concrete, mortar, brick, plaster, and natural stone such as granite, limestone, sandstone, or marble.

[0162] In these methods, one or both substrates are preferably metal or glass ceramic or glass or glass fiber reinforced plastic or carbon fiber reinforced plastic or epoxy based thermosetting resin.

[0163] The substrate can be pretreated, if necessary, before applying the composition, including, inter alia, physical and / or chemical cleaning processes and the application of an adhesion promoter, adhesion promoter solution, or primer.

[0164] The adhesive bonding methods described result in an article in which two substrates are bonded together by a composition.

[0165] The article is in particular a lightweight construction sandwich element, an erected structure, such as a bridge, an industrial or consumer product, in particular a window, a wind turbine rotor, or a form of transport, in particular a vehicle, preferably a car, bus, truck, rail vehicle, or ship, or an aircraft or helicopter, or a construction material to which such an article can be attached.

[0166] The polyurethane compositions described are characterized by very constant high strength and elasticity over a wide temperature range from -35°C to 85°C, and by good, temperature-independent adhesion properties to metal substrates. These properties make them highly suitable as structural adhesives for bonds exposed to outdoor stresses at ambient temperatures.

[0167] The present invention therefore further provides the use of the described polyurethane compositions as structural adhesives for adhesively bonding two substrates.

[0168] The polyurethane compositions described can likewise be used advantageously as potting compounds, in particular for filling gaps and joints, for repair purposes as ballast compensation compounds, or for the protection of electronic components.

[0169] The polyurethane composition is further preferably used as a casting compound, in particular as an electrical potting compound. Thus, in a further aspect, the present invention includes the use of a two-component polyurethane composition as a potting compound, in particular as an electrical potting compound.

[0170] In a further aspect, the present invention includes a method of filling joints and gaps in a substrate, comprising the steps of: (a) mixing the first and second components of the two-component polyurethane composition; (b) applying the mixed polyurethane composition to a joint between two substrates or to a gap on the surface of a substrate; (c) curing the polyurethane composition in the joint or gap;

[0171] Particularly suitable substrates are metal, plastic, wood, glass, ceramic and fiber-reinforced plastic, especially metal and fiber-reinforced plastic. Thus, in a further aspect, the present invention also includes a filled article that has been embedded by the method described above.

[0172] The polyurethane composition is preferably used as a matrix in a composite material, where the polyurethane composition functions as a binder in which fibers or other reinforcing structures are embedded. Thus, in a further aspect, the present invention includes the use of a two-component polyurethane composition as a matrix in a composite material. [Example]

[0173] Substances used:

[0174] [Table 1]

[0175] Preparation of Polyurethane Composition For each composition, the specified amount (in parts by weight or % by weight) of the first component A listed in the table was processed into a homogeneous paste using a vacuum dissolver with moisture exclusion and stored. The second component B listed in the table was processed and stored in the same manner. The two components were then processed for 30 seconds in a SpeedMixer® (DAC 150 FV, Hauschild) to form a homogeneous paste, which was immediately tested as follows:

[0176] To determine the mechanical properties, the adhesives were molded into dumbbell shapes according to ISO 527, Part 2, 1B, at 23°C and 50% RH (relative humidity) for the times specified in the table (1 and 7 days), followed by a 7-day storage / cure at 90°C. After a 24-hour conditioning period at 23°C and 50% RH, the modulus of elasticity, tensile strength, and elongation at break of the thus prepared test specimens in the elongation range of 0.05-0.25% were measured on a Zwick Z020 tensile testing machine according to DIN EN ISO 527 at 23°C and 50% RH with a test speed of 10 mm / min.

[0177] To measure the tensile shear strength, various test specimens were prepared in each case by applying the adhesive 1 minute after the end of the mixing time to an overlapping area of 15 x 45 mm with a layer thickness of 2 mm between two heptane-degreased and cathodically electroplated steel plates. These test specimens were then stored / cured for 24 hours at 23°C ("cold conditions"). Some of the samples were then further stored / cured for 10 days under hot and humid conditions (40°C and 100% relative humidity). After a conditioning period of 24 hours at 23°C and 50% RH, the tensile shear strength was measured according to DIN EN 1465.

[0178] The viscosity was measured on an MCR302 parallel plate rheometer (Anton Paar) with a plate diameter of 25 mm and a plate distance of 1 mm at 10 s -1 at a frequency of 100 Hz and a temperature of 20° C. This was done by first manually mixing the two components with a spatula in a beaker for 30 seconds and then immediately applying them to a measuring plate.

[0179] The measurement results are shown in the table.

[0180] In the table, compositions according to the invention are identified with "I" (I-1 to I-11) and reference compositions not according to the invention are identified with "R" (R-1 to R-4).

[0181] [Table 2]

[0182] [Table 3]

[0183] The viscosity measurements in Tables 2-5 show that the compositions of the present invention continue to have low viscosity for a relatively long time (time t1) and then cure very rapidly (times t2 and t3, especially the difference between times t2 and t3).

[0184] The subtraction of time t3 minus time t2 indicates the curing speed. The smaller this value, the faster the composition cures. To indicate a sufficient curing speed according to the present invention, the value of t3-t2 should be less than 5, preferably less than 4.5. In a particularly preferred embodiment, the value of t3-t2 is less than 2, in particular less than 1.5.

[0185] [Table 4]

[0186] [Table 5]

[0187] [Table 6]

[0188] Table 5 shows that for Experiments 1 to 10, a too high application temperature affects the curing speed and pot life, which means that the application and curing of the composition can also be further affected by the application temperature.

[0189] Table 6 shows the results of the synthesis of the diol P3 (in this case butane-1,4-diol from Example I-11). It has been found that the use of It shows. The present disclosure includes the following aspects. <Aspect 1> A polyurethane composition consisting of a first component A and a second component B, - said first component A comprises: 30% to 99% by weight, based on component A, of a polyol mixture P comprising: 100 parts by weight of at least one hydrophobic polyol P1, - 10 to 75 parts by weight of at least one hydrophilic polyol P2, - 0 to 25 parts by weight of at least one diol P3 having two hydroxyl groups linked via a C2 to C9 carbon chain, and - at least one compound T having at least one thiol group; and - said second component B comprises: - at least one polyisocyanate I; one of the two components further comprises at least one metal catalyst K for the reaction of hydroxyl groups capable of forming thio complexes with isocyanate groups, and the molar ratio of the total thiol groups in the at least one compound T to the total metal atoms in the at least one metal catalyst K is 1:1 to 250:1; Polyurethane composition. <Aspect 2> 2. The polyurethane composition of claim 1, wherein the metal catalyst K comprises a bismuth(III) compound, preferably a bismuth(III) carboxylate. <Aspect 3> 3. The polyurethane composition of aspect 2, wherein the bismuth(III) compound further comprises an 8-hydroxyquinoline ligand or a 1,3-ketoamide ligand. <Aspect 4> Aspect 4. The polyurethane composition of any one of aspects 1 to 3, wherein the diol P3 is a linear aliphatic diol having two primary hydroxyl groups linked via a C4 to C9 carbon chain, and in particular selected from the group consisting of butane-1,4-diol, pentane-1,5-diol, hexane-1,6-diol, and nonane-1,9-diol. <Aspect 5> Aspect 5. The polyurethane composition of any one of aspects 1 to 4, wherein the at least one compound T comprises a polythiol compound having 2 to 6 thiol groups or a mercaptosilane. <Aspect 6> 6. The polyurethane composition of claim 5, wherein the at least one compound T is selected from the group consisting of ethylene glycol di(3-mercaptopropionate), ethylene glycol dimercaptoacetate, dipentaerythritol hexa(3-mercaptopropionate), and 3-mercaptopropyltrimethoxysilane. <Aspect 7> 7. The polyurethane composition of any one of aspects 1 to 6, wherein the molar ratio of total thiol groups in the at least one compound T to total metal atoms in the at least one metal catalyst K is from 5:1 to 100:1. <Aspect 8> Aspect 8. The polyurethane composition according to any one of aspects 1 to 7, wherein the metal catalyst K is present in the first component A. <Aspect 9> 9. The polyurethane composition according to any one of the preceding aspects, wherein the hydrophilic polyol P2 is a polyether polyol, in particular a polyether polyol having an average OH functionality of at least 2.5 and preferably having propylene glycol repeat units in the polymer backbone. <Aspect 10> Aspects 1 to 9. Polyurethane composition according to any one of aspects 1 to 9, characterized in that the polyisocyanate I is in the form of diphenylmethane 4,4'-, 2,4'- or 2,2'-diisocyanate, which is liquid at room temperature, or any desired mixture of these isomers (MDI), in the form of polymeric MDI or oligomers or derivatives, in particular MDI containing a proportion of carbodiimides. <Aspect 11> Aspect 11. The polyurethane composition according to any one of aspects 1 to 10, wherein the second component B comprises a polyurethane polymer containing an isocyanate group. <Aspect 12> 12. The polyurethane composition according to any one of the preceding aspects, wherein the hydrophobic polyol P1 is a polybutadiene polyol, a polyester polyol based on dimer fatty acid, a polytetramethylene oxide diol, or a mixture of said polyols, and wherein the polyol P1 has an average OH functionality of 2 to 2.5. <Aspect 13> 1. A method of adhesively bonding a first substrate to a second substrate, comprising: - mixing the first component and the second component of the polyurethane composition according to any one of aspects 1 to 12; - applying the mixed polyurethane composition to at least one of the substrate surfaces to be bonded; - joining the substrates to be bonded within an open time; - curing said polyurethane composition. <Aspect 14> 14. An article obtainable by the adhesive bonding method according to embodiment 13. <Aspect 15> 13. Use of the polyurethane composition according to any of aspects 1 to 12 as a structural adhesive for adhesive bonding of two substrates or as a matrix in a composite material.

Claims

1. A polyurethane composition comprising a first component A and a second component B, said first component A comprises: 30% to 99% by weight, based on component A, of a polyol mixture P comprising: 100 parts by weight of at least one polyol P1, - 10 to 75 parts by weight of at least one polyol P2, - 0 to 25 parts by weight of at least one diol P3 having two hydroxyl groups linked via a C2 to C9 carbon chain, and at least one compound T having at least one thiol group; and said second component B comprises: at least one polyisocyanate I; one of the two components further comprises at least one metal catalyst K for the reaction of hydroxyl groups capable of forming thio complexes with isocyanate groups, and the molar ratio of total thiol groups in said at least one compound T to total metal atoms in said at least one metal catalyst K is from 1:1 to 250:1; the polyol P1 is different from the polyol P2 and is a polybutadiene polyol, a polyester polyol based on dimer fatty acid, a polytetramethylene oxide diol, or a mixture of the above polyols, the polyol P1 having an average OH functionality of 2 to 2.5, the polyol P2 is a polyether polyol having an average OH functionality of at least 2.5; Polyurethane composition.

2. 2. The polyurethane composition of claim 1, wherein the metal catalyst K comprises a bismuth(III) compound.

3. 3. The polyurethane composition of claim 2, wherein the bismuth(III) compound further comprises an 8-hydroxyquinoline ligand or a 1,3-ketoamide ligand.

4. 4. The polyurethane composition according to claim 1, wherein the diol P3 is a linear aliphatic diol having two primary hydroxyl groups linked via a C4-C9 carbon chain.

5. 5. The polyurethane composition according to claim 1, wherein the at least one compound T comprises a polythiol compound having 2 to 6 thiol groups or a mercaptosilane.

6. 6. The polyurethane composition according to claim 5, characterized in that the at least one compound T is selected from the group consisting of ethylene glycol di(3-mercaptopropionate), ethylene glycol dimercaptoacetate, dipentaerythritol hexa(3-mercaptopropionate), and 3-mercaptopropyltrimethoxysilane.

7. 7. The polyurethane composition according to claim 1, wherein the molar ratio of all thiol groups in the at least one compound T to all metal atoms in the at least one metal catalyst K is from 5:1 to 100:

1.

8. 8. The polyurethane composition according to claim 1, wherein the metal catalyst K is present in the first component A.

9. 9. Polyurethane composition according to any one of claims 1 to 8, characterized in that the polyisocyanate I is in the form of diphenylmethane 4,4'-, 2,4'- or 2,2'-diisocyanate, which is liquid at room temperature, or any desired mixture of these isomers (MDI), in the form of polymeric MDI or MDI containing a proportion of oligomers or derivatives.

10. 10. The polyurethane composition according to claim 1, wherein the second component B comprises a polyurethane polymer containing isocyanate groups.

11. 1. A method of adhesively bonding a first substrate to a second substrate, comprising: - mixing the first and second components of the polyurethane composition according to any one of claims 1 to 10, applying the mixed polyurethane composition to at least one of the surfaces of the substrate to be bonded; - joining the substrates to be bonded within the open time; - curing said polyurethane composition.

12. 12. An article obtainable by the adhesive bonding method according to claim 11.

13. Use of a polyurethane composition according to any one of claims 1 to 10 as a structural adhesive for adhesively bonding two substrates or as a matrix in a composite material.

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