Polyurethane composition having good adhesion to plastics

Abstract

The present invention relates to a moisture-curable polyurethane composition comprising: (i) at least one linear isocyanate group-containing polymer (P1) having an NCO content ranging from 0.3 to 3.3% by weight, the polymer being obtained by reacting at least one aromatic diisocyanate monomer with a polyether diol having an OH value ranging from 5 to 37 mg KOH / g; (ii) at least one branched isocyanate group-containing polymer (P2) having an NCO content ranging from 1 to 10% by weight, the polymer being obtained by reacting at least one aromatic diisocyanate monomer with at least one polyether triol having an average OH functionality of at least 2.2 and an OH value ranging from 16 to 380 mg KOH / g; and (iii) a softener content of up to 15% by weight, based on the total composition, wherein the polymers (P1) and (P2) are present in a weight ratio ranging from 80 / 2 to 95 / 5. The present invention also relates to the use of the composition as an elastic adhesive, sealant, or coating. The compositions according to the present invention provide high elongation, surprisingly high strength and surprisingly good adhesion to plastic substrates, even when the compositions are formulated to have very low diisocyanate monomer content, and therefore provide an attractive EHS classification.

Description

[Technical Field]

[0001] The present invention relates to moisture-curable polyurethane compositions having good adhesion to plastic substrates and their use as elastic adhesives. [Background technology]

[0002] Polyurethane compositions, which crosslink and cure to elastomers by the reaction of isocyanate groups with moisture or water, are used particularly in the construction and manufacturing industries as elastic adhesives or sealants, for example, to join components in assemblies or to fill joints. Due to their adhesive and elastic properties, they can gently dampen and buffer forces acting on substrates, such as those caused by vibrations or temperature changes. Plasticizers promote high flexibility here, but are detrimental to the development of good adhesion to plastic substrates.

[0003] Polyurethane compositions contain a polymer containing isocyanate groups as a binder, which is prepared by reacting diisocyanate monomers with polyols. Due to chain extension reactions, the resulting polymers typically have residual diisocyanate monomer contents ranging from 1% to 3% by weight. Diisocyanate monomers can be harmful to health. In particular, formulations containing diisocyanate monomers at concentrations greater than 0.1% by weight must provide hazard symbols and warning messages on labels and data sheets, and may be subject to restrictions on sale and use in some countries. Therefore, interest is growing in polyurethane compositions with low monomer contents, particularly below 0.1% by weight. An attractive route to isocyanate-containing polymers with low diisocyanate monomer contents is to use an excess of diisocyanate monomer in the polymer preparation and then remove most of the unconverted diisocyanate monomer by distillation. This route is particularly easy to implement with low-molecular-weight, and therefore volatile, diisocyanate monomers, such as hexanediisocyanate. However, polymers based on it have slower cure times and lower mechanical strength. Polymers based on diphenylmethane 4,4'-diisocyanate (4,4'-MDI) allow for rapid and reliable cure, resulting in high strength combined with high modulus. However, the low volatility of 4,4'-MDI makes distillation of the monomeric diisocyanates quite challenging to manufacture.

[0004] Elastic adhesives for bonding plastic substrates are increasingly needed in the industry, for example, for bonding headlamp housings or panoramic roofs in automobiles, organic glass in ships or trains, or various parts of trailers. The adhesives herein cure quickly and reliably, are highly elastic while having high strength, and have high bond strength even under heat and water stress without complex pre-treatment of the plastic substrate. However, adhesives based on polymers with low monomer levels show weaknesses in enhancing adhesion to plastic substrates, especially since they are substantially devoid of diisocyanate monomers. Summary of the Invention [Problem to be solved by the invention]

[0005] Therefore, it is an object of the present invention to provide a moisture-curable polyurethane composition that cures rapidly and reliably and that enhances good adhesion to plastic substrates, along with high elongation and strength, even at low diisocyanate monomer contents. [Means for solving the problem]

[0006] This object is achieved by the composition described in claim 1, which contains a combination of a linear long-chain polymer P1 and a branched polymer P2 in a weight ratio ranging from 80 / 20 to 95 / 5, and a plasticizer content of up to 15% by weight. Surprisingly, compositions with the inventive weight ratios of polymers P1 and P2 exhibit excellent adhesion to substrates, especially polycarbonates, even after heat and water stress. Corresponding compositions with a high proportion of branched polymer P2 exhibit significantly poorer adhesion, while even at lower branched polymer P2 contents, the tensile strength of the cured compositions drops significantly and sharply, becoming insufficient. What is particularly surprising about the inventive compositions is the fact that, despite low branched polymer P2 contents and even at very low diisocyanate monomer contents, products with high strength (tensile strength and modulus) are obtained.

[0007] The compositions of the present invention allow for elastic adhesives with good storage stability when excluding moisture, long open times, combined with rapid cure and high elongation, surprisingly high strength and surprisingly good adhesion to plastic substrates, along with a more attractive EHS classification.

[0008] 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

[0009] The present invention provides a moisture-curable polyurethane composition comprising: (i) at least one linear polymer P1 containing isocyanate groups and having an NCO content ranging from 0.3% to 3.3% by weight, obtained from the reaction of at least one aromatic diisocyanate monomer with a polyether diol having an OH value ranging from 5 to 37 mg KOH / g, (ii) at least one branched polymer P2 containing isocyanate groups and having an NCO content ranging from 1% to 10% by weight, obtained from the reaction of at least one aromatic diisocyanate monomer with at least one polyether triol having an average OH functionality of at least 2.2 and an OH number ranging from 16 to 380 mg KOH / g, (iii) a plasticizer content of 15% by weight or less based on the total composition; wherein the polymer P1 and the polymer P2 are present in a weight ratio ranging from 80 / 20 to 95 / 5; A moisture-curable polyurethane composition is provided.

[0010] "Diisocyanate monomer" means an organic compound having two isocyanate groups separated by a divalent hydrocarbyl group having from 4 to 15 carbon atoms.

[0011] By "aromatic" isocyanate groups is meant groups that are directly bonded to aromatic carbon atoms. Isocyanates that have predominantly aromatic isocyanate groups are accordingly called "aromatic isocyanates."

[0012] By "aliphatic" isocyanate group is meant a group that is directly bonded to an aliphatic or alicyclic carbon atom. Isocyanates having predominantly aliphatic isocyanate groups are accordingly called "aliphatic isocyanates."

[0013] The term "aromatic diisocyanate monomer" means a diisocyanate monomer having an aromatic isocyanate group.

[0014] "NCO content" means the content of isocyanate groups in % by weight.

[0015] "Plasticizer" means a substance that is liquid at room temperature and that remains unchanged in a composition after its hardening, plasticizing the hardened composition.

[0016] "Molecular weight" means the molar mass (grams / mole) of a molecule or molecular residue. "Average molecular weight" means the average molecular weight (M n ) It is determined by gel permeation chromatography (GPC) against polystyrene as a standard.

[0017] A substance or composition is said to be "storage-stable" or "storable" if it can be stored at room temperature in a suitable container for an extended period of time, usually at least 3 months, preferably up to 6 months or more, without this storage resulting in any change in its application or use characteristics to an extent relevant to its use.

[0018] "Plastic" means an organic material based on macromolecules.

[0019] "Room temperature" means a temperature of 23°C.

[0020] All industry standards and criteria mentioned herein relate to the version in effect on the date of first filing.

[0021] Weight percentage, abbreviated as wt. %, unless otherwise specified, means the ratio (by mass) of a component of a composition or molecule relative to the entire composition or molecule. The terms "mass" and "weight" are used interchangeably herein.

[0022] The polymer P1 preferably has an NCO content in the range from 0.5% to 2.6% by weight, in particular from 0.7% to 2.0% by weight, more preferably from 0.9% to 2.0% by weight.

[0023] Suitable aromatic diisocyanate monomers are in particular diphenylmethane 4,4'-diisocyanate, optionally with a fraction of diphenylmethane 2,4'- and / or 2,2'-diisocyanate (MDI), its mixture with tolylene 2,4-diisocyanate or tolylene 2,6-diisocyanate (TDI), phenylene 1,4-diisocyanate (PDI), 2,3,5,6-tetramethyl-1,4-diisocyanatobenzene, naphthalene 1,5-diisocyanate (NDI) or 3,3'-dimethyl-4,4'-diisocyanatodiphenyl (TODI). Among these, diphenylmethane 4,4'-diisocyanate, tolylene 2,4-diisocyanate or phenylene 1,4-diisocyanate are preferred.

[0024] A particularly preferred aromatic diisocyanate monomer is diphenylmethane 4,4'-diisocyanate (4,4'-MDI). This 4,4'-MDI is a quality containing only a small proportion of diphenylmethane 2,4'- and / or 2,2'-diisocyanate and is solid at room temperature. It allows for particularly rapid curing and particularly high strength polyurethane compositions, combined with high elongation and elasticity. 4,4'-MDI is preferably distilled and has a purity of at least 95%, particularly at least 97.5%. Commercially available diphenylmethane 4,4'-diisocyanate of this quality is, for example, Desmodur® 44MC (Covestro), or Lupranat® MRS or ME (BASF), or Suprasec® 1400 (Huntsman).

[0025] The polyether diol preferably contains repeating units selected from the group consisting of 1,2-ethyleneoxy, 1,2-propyleneoxy, 1,3-propyleneoxy, 1,2-butyleneoxy, and 1,4-butyleneoxy. 1,2-propyleneoxy groups with or without a specific proportion of 1,2-ethyleneoxy groups are preferred.

[0026] More specifically, the polyether diol contains 80 to 100% by weight of 1,2-propyleneoxy groups and 0 to 20% by weight of 1,2-ethyleneoxy groups. When the polyether diol contains 1,2-ethyleneoxy groups, the 1,2-propyleneoxy groups and the 1,2-ethyleneoxy groups preferably form uniform blocks, with the poly(1,2-ethyleneoxy) blocks at the ends of the chains.

[0027] The polyether diols preferably have an OH number in the range from 6 to 33 mg KOH / g, in particular from 9 to 30 mg KOH / g, in particular from 12 to 30 mg KOH / g.

[0028] The polyether diol preferably has an average molecular weight M in the range of 3,000 to 20,000 g / mol, more preferably 3,500 to 18,000 g / mol, in particular 4,000 to 12,000 g / mol, most preferably 4,000 to 9,000 g / mol. n It has.

[0029] The polyetherdiol preferably has an average OH functionality of at least 1.8, in particular at least 1.9. As a result of its production, commercially available polyetherdiols contain a certain content of monools, and as a result, the average OH functionality is usually slightly below 2.

[0030] The polyether diol preferably has an unsaturation level of less than 0.02 meq / g, in particular less than 0.01 meq / g, measured according to ASTM D-2849-69. Polyether diols having an unsaturation level of less than 0.01 meq / g are particularly prepared using catalysts known as double metal cyanide complex catalysts (DMC catalysts).

[0031] The polyether diol more preferably has an OH number in the range of 6 to 33 mg KOH / g, preferably 9 to 30 mg KOH / g, in particular 12 to 30 mg KOH / g, and an average OH functionality of at least 1.9.

[0032] Suitable polyether diols are commercially available, for example, as Acclaim® Polyol 4200, Acclaim® Polyol 8200N, Acclaim® Polyol 12200N or Acclaim® Polyol 18200N (all Covestro), Lupranol® 1005 / 1 (BASF), Voranol® P4000 (Dow) or Preminol® S4013F (Asahi Glass Co., Ltd.).

[0033] Preferably, the polymer P1 has an average molecular weight M in the range of 4,000 to 40,000 g / mol, determined by gel permeation chromatography (GPC) against polystyrene as standard using tetrahydrofuran as mobile phase and a refractive index detector. n More preferably, the average molecular weight M n is in the range of 4,500 to 30,000 g / mol, particularly 5,000 to 25,000 g / mol, and more preferably 5,000 to 15,000 g / mol.

[0034] The reaction of aromatic diisocyanate monomers with polyether diols to prepare the linear polymers P1 is preferably carried out at temperatures ranging from 20 to 160°C, in particular from 40 to 140°C, optionally in the presence of a suitable catalyst, with the exclusion of water.

[0035] The reaction is preferably carried out at an NCO / OH ratio ranging from 1.3 / 1 to 20 / 1. The diisocyanate monomers remaining in the reaction mixture after reaction of the OH groups can be removed, in particular by distillation.

[0036] In one embodiment of the present invention, the diisocyanate monomers are not removed from the polymer. In that case, the NCO / OH ratio in the reaction is preferably in the range of 1.3 / 1 to 2.5 / 1. Such polymer P1 preferably contains not more than 3.5% by weight of diisocyanate monomers.

[0037] Preferably, the polymer P1 is prepared so that the NCO / OH ratio in the reaction is at least 4 / 1, and the majority of the aromatic diisocyanate monomers are subsequently removed by a suitable separation process, so that the resulting polymer P1 containing isocyanate groups after distillation contains not more than 0.5% by weight, in particular not more than 0.3% by weight, of diisocyanate monomers. Such polymer P1 allows for polyurethane compositions with a particularly attractive EHS classification.

[0038] The NCO / OH ratio is preferably in the range of 5 / 1 to 15 / 1.

[0039] A preferred separation method for removing the aromatic diisocyanate monomer is a distillation method, in particular thin film distillation or short path distillation, preferably applying a reduced pressure.

[0040] Particularly preferred is a multistage process in which the aromatic diisocyanate monomer is removed in a short-path evaporator using a jacket temperature in the range of 120-200°C and a pressure of 0.001-0.5 mbar. In the case of 4,4'-MDI, which is the preferred aromatic diisocyanate monomer, the distillative removal is particularly demanding. For example, it must be ensured that the condensate does not solidify and block the system. It is preferred to operate at a jacket temperature in the range of 160-200°C at 0.001-0.5 mbar and condense the removed monomer at a temperature in the range of 40-60°C.

[0041] It is preferred to react the aromatic diisocyanate monomer with the polyether diol and then remove most of the diisocyanate monomer remaining in the reaction mixture without using a solvent or entraining agent. It is preferred to subsequently recycle the aromatic diisocyanate monomer removed after the reaction, i.e., to use it again to prepare a polymer containing isocyanate groups.

[0042] The linear polymer P1 is liquid at room temperature and has a relatively low viscosity. It preferably has a viscosity at 20°C of 60 Pa.s or less, more preferably 45 Pa.s or less, in particular 30 Pa.s or less. Viscosity is measured here at a shear rate of 10 s -1 is determined using a cone and plate viscometer.

[0043] In this reaction, the OH groups of the polyether diol react with the isocyanate groups of the aromatic diisocyanate monomer. This also results in a reaction called chain extension, in that there is a reaction of the OH groups and / or isocyanate groups of the reaction product of the diol and the diisocyanate monomer. The higher the NCO / OH ratio selected, the lower the level of chain extension that occurs, the lower the polydispersity, and therefore the lower the viscosity of the resulting polymer. A measure of the rate of chain extension is the average molecular weight of the polymer or the width and distribution of the peaks in GPC analysis. If unconverted diisocyanate monomer is removed from the polymer by distillation, the effective NCO content of the polymer relative to the theoretical NCO content calculated from the reaction of all OH groups with the aromatic diisocyanate monomer is a further measure of the rate of chain extension.

[0044] Preferably, the polymer P1 from which the diisocyanate monomer has been removed by distillation contains only a low content of chain-extended components, the NCO content of which is preferably at least 90%, in particular at least 95%, of the theoretical NCO content calculated from the addition of one mole of diisocyanate monomer per mole of OH group of the polyether diol.

[0045] The polymer P2 preferably has an NCO content in the range from 1.2% to 7% by weight, in particular from 1.4% to 3.5% by weight.

[0046] Suitable aromatic diisocyanate monomers are in particular diphenylmethane 4,4'-diisocyanate, optionally with a fraction of diphenylmethane 2,4'- and / or 2,2'-diisocyanate (MDI), its mixture with tolylene 2,4-diisocyanate or tolylene 2,6-diisocyanate (TDI), phenylene 1,4-diisocyanate (PDI), 2,3,5,6-tetramethyl-1,4-diisocyanatobenzene, naphthalene 1,5-diisocyanate (NDI) or 3,3'-dimethyl-4,4'-diisocyanatodiphenyl (TODI). Among these, diphenylmethane 4,4'-diisocyanate, tolylene 2,4-diisocyanate or phenylene 1,4-diisocyanate are preferred.

[0047] A particularly preferred aromatic diisocyanate monomer is diphenylmethane 4,4'-diisocyanate (4,4'-MDI). The 4,4'-MDI is preferably distilled and has a purity of at least 95%, especially at least 97.5%.

[0048] The polyether triol preferably contains repeating units selected from the group consisting of 1,2-ethyleneoxy, 1,2-propyleneoxy, 1,3-propyleneoxy, 1,2-butyleneoxy, and 1,4-butyleneoxy, with 1,2-propyleneoxy groups with or without a specific proportion of 1,2-ethyleneoxy groups being preferred.

[0049] More specifically, the polyether triol has 80% to 100% by weight of 1,2-propyleneoxy groups and 0% to 20% by weight of 1,2-ethyleneoxy groups, based on all repeating units.

[0050] The polyether triol preferably has an OH number in the range from 21 to 160 mg KOH / g, in particular from 25 to 60 mg KOH / g.

[0051] The polyether triol preferably has an average OH functionality in the range of 2.3 to 3. As a result of its production, commercially available polyether triols contain a certain content of monools, and as a result, the average OH functionality is usually slightly below 3. Thus, polyether triols usually contain trifunctional and monofunctional components.

[0052] The polyether triols preferably have an average molecular weight M in the range of 450 to 10,000 g / mol, more preferably 1,000 to 8,000 g / mol, especially 2,800 to 6,500 g / mol. n It has.

[0053] The polyether triol is preferably initiated by trimethylolpropane or, especially, glycerol.

[0054] Suitable polyether triols are, for example, Desmophen® 3061BT, Desmophen® 4042BT, Desmophen® 5031BT, Desmophen® 5034BT or Acclaim® Polyol 6300 (all Covestro), Lupranol® 2004 / 1 or Lupranol® 2095 (BASF), Voranol® CP450, Voranol® CP755, Voranol® CP It is commercially available as Voranol® CP1050, Voranol® CP3055, Voranol® CP4755, Voranol® 5815 or Voranol® CP6001 (Dow), Caradol® ET34-08 or Caradol® ET28-03 (Shell), or Preminol® 7001K or Preminol® S3011 (Asahi Glass Co., Ltd.).

[0055] Preferably, the polymer P2 has an average molecular weight M in the range of 1,200 to 40,000 g / mol, determined by gel permeation chromatography (GPC) against polystyrene as standard using tetrahydrofuran as the mobile phase and a refractive index detector. n More preferably, the average molecular weight M n is in the range of 2,000 to 30,000 g / mol, particularly 4,000 to 20,000 g / mol.

[0056] The reaction of aromatic diisocyanate monomers with polyether triol to prepare the branched polymer P2 is preferably carried out at temperatures ranging from 20 to 160°C, in particular from 40 to 140°C, optionally in the presence of a suitable catalyst, with the exclusion of water. The reaction is preferably carried out at an NCO / OH ratio ranging from 1.7 / 1 to 20 / 1. The diisocyanate monomers remaining in the reaction mixture after the reaction of the OH groups can be removed, in particular by distillation.

[0057] In a preferred embodiment of the present invention, the diisocyanate monomer is not removed from the polymer. In that case, the NCO / OH ratio in the reaction is preferably in the range of 1.9 / 1 to 2.5 / 1. Such polymers P2 preferably contain not more than 3.5% by weight of diisocyanate monomer. In preparing such polymers P2 together with polyethertriols, it is possible to use specific ratios of polyetherdiols, in particular those having OH values ​​in the range of 25 to 115 mg KOH / g, preferably 25 to 60 mg KOH / g. The ratio of polyethertriol to polyetherdiol is preferably selected herein so that the average NCO functionality of polymer P2 ultimately is at least 2.2.

[0058] More preferably, the polymer P2 is prepared so that the NCO / OH ratio in the reaction is at least 4 / 1, particularly in the range of 5 / 1 to 10 / 1, and most of the aromatic diisocyanate monomers are subsequently removed by a suitable separation process, so that the resulting polymer P2 containing isocyanate groups after distillation contains 0.5% by weight or less, particularly 0.3% by weight or less of diisocyanate monomers. Such polymer P2 is a particularly low viscosity polymer, which contributes to the attractive EHS classification of the polyurethane composition.

[0059] Preferably, the aromatic diisocyanate monomers for preparing the two polymers P1 and P2 are the same aromatic diisocyanate monomers.

[0060] Preferably, the aromatic diisocyanate monomer for the two polymers P1 and P2 is 4,4'-MDI.

[0061] Preferred polymers enable polyurethane compositions to have a particularly advantageous combination of high strength and good adhesion to plastic substrates.

[0062] Polymer P1 and polymer P2 are present in the moisture-curable polyurethane composition in a weight ratio ranging from 80 / 20 to 95 / 5, at which weight ratio there is a surprising combination of good adhesion to plastic substrates and high strength.

[0063] The weight ratio of the polymers P1 and P2 is preferably in the range of 84 / 16 to 93 / 7.

[0064] If the polyetherdiol for the preparation of polymer P1 has an OH number in the range from 22 to 37 mg KOH / g, in particular from 25 to 33 mg KOH / g, the weight ratio of polymers P1 and P2 is preferably in the range from 88 / 12 to 93 / 7.

[0065] If the polyetherdiol for the preparation of polymer P1 has an OH number in the range from 5 to 21 mg KOH / g, in particular from 6 to 19 mg KOH / g, the weight ratio of polymers P1 and P2 is preferably in the range from 84 / 16 to 91 / 9.

[0066] At the preferred weight ratios, the combination of good adhesion and high strength is particularly advantageous.

[0067] Preferably, the moisture-curable polyurethane composition has a total content of polymer P1 and polymer P2 in the range of 20% to 80% by weight, in particular 30% to 70% by weight, more preferably 40% to 60% by weight, based on the total composition.

[0068] In addition to polymers P1 and P2, the moisture-curable polyurethane composition may contain at least one further polymer containing isocyanate groups that does not correspond to polymers P1 or P2. Suitable polymers are polyether-based polymers with aliphatic isocyanate groups and polymers containing polyester polyols, polycarbonate polyols, poly(meth)acrylate polyols, polyhydroxy-functional fats or oils, polyhydrocarbon polyols or further polyols.

[0069] The moisture-curable polyurethane composition preferably contains a total content of diisocyanate monomers of less than 0.1% by weight.

[0070] The moisture-curable polyurethane composition optionally contains a plasticizer, in which case the plasticizer is present in an amount of 15% by weight or less based on the total composition. Plasticizers are likely to have a detrimental effect on the adhesion of plastic substrates because too much is used. Preferably, the moisture-curable polyurethane composition contains 10% by weight or less, particularly 5% by weight or less, of plasticizer.

[0071] Suitable plasticizers are in particular carboxylic acid esters, such as phthalates, in particular diisononyl phthalate (DINP), diisodecyl phthalate (DIDP) or di(2-propylheptyl)phthalate (DPHP), hydrogenated phthalates or cyclohexane-1,2-dicarboxylic acid esters, in particular hydrogenated diisononyl phthalate or diisononyl cyclohexane-1,2-dicarboxylate (DINCH), terephthalates, in particular bis(2-ethylhexyl)terephthalate (DOTP) or diisononyl terephthalate (DINT), hydrogenated terephthalates or cyclohexane-1,4-dicarboxylic acid esters, in particular hydrogenated bis(2-ethylhexyl)terephthalate, or Examples of suitable plasticizers include bis(2-ethylhexyl)cyclohexane-1,4-dicarboxylate, hydrogenated diisononyl terephthalate, diisononyl cyclohexane-1,4-dicarboxylate, isophthalate, trimellitate, adipate, especially dioctyl adipate, azelate, sebacate, benzoate, glycol ether, glycol ester, and plasticizers having a polyether structure, especially polypropylene oxide mono-, di-, or triol having blocked hydroxyl groups in the form of acetate groups, organic phosphoric or sulfonic acid esters, polybutene, polyisobutene, and plasticizers derived from natural fats or oils, especially epoxidized soybean or linseed oil. Preferred plasticizers are those having a phthalate, hydrogenated phthalate, adipate, or polyether structure.

[0072] The moisture-curable polyurethane composition preferably comprises at least one additional component selected from the group consisting of fillers, diisocyanate oligomers, blocked amines, catalysts, and stabilizers.

[0073] Suitable fillers are, in particular, ground or precipitated calcium carbonate, optionally coated with a fatty acid, in particular stearic acid, baryta, quartz flour, quartz sand, dolomite, wollastonite, calcined kaolin, layered silicates such as mica or talc, zeolites, aluminum hydroxide, magnesium hydroxide, silica, including finely divided silica obtained from pyrolysis processes, cement, gypsum, fly ash, industrially produced carbon black, graphite, metal powders such as aluminum, copper, iron, silver or steel, PVC powder or hollow beads. Calcium carbonate, optionally coated with a fatty acid, in particular stearic acid, calcined kaolin or industrially produced carbon black are preferred.

[0074] Suitable diisocyanate oligomers are, in particular, HDI biurets, such as Desmodur® N100 or N3200 (Covestro), Tolonate® HDB or HDB-LV (Vencorex) or Duranate® 24A-100 (Asahi Kasei Corporation); HDI isocyanurates, such as Desmodur® N3300, N3600 or N3790BA (all Covestro), Tolonate® HDT, HDT -LV or HDT-LV2 (Vencorex), Duranate® TPA-100 or THA-100 (Asahi Kasei Corporation) or Coronate® HX (Nippon Polyurethane Industry Co., Ltd.); HDI uretdiones, such as Desmodur® N3400 (Covestro); HDI iminooxadiazinediones, such as Desmodur® XP2410 (Covestro); HDI allophanates, such as Desmodur® VP LS2102 (Covestro); IPDI isocyanurates, such as Desmodur® Z4470 (Covestro) in solution or Vestanat® T1890 / 100 (Evonik) in solid form; TDI oligomers, such as Desmodur® IL (Covestro); or mixed isocyanurates based on TDI / HDI, such as Desmodur® HL (Covestro) (where "HDI" means hexane 1,6-diisocyanate, "IPDI" means isophorone diisocyanate, and "TDI" means tolylene 2,4-diisocyanate or its mixture with tolylene 2,6-diisocyanate). Preferably, the moisture-curable polyurethane composition contains a low content of diisocyanate oligomers, preferably less than 5% by weight, more preferably less than 3% by weight, and especially less than 1% by weight, based on the total composition.

[0075] Suitable blocked amines preferably have at least one aldimino or oxazolidinino group, which upon contact with moisture can be hydrolyzed and react with available isocyanate groups, releasing the amino group and promoting rapid, blister-free curing, a particularly non-stick surface, and / or particularly good mechanical properties.

[0076] Preferred oxazolidines are oxazolidines derived from bisoxazolidine, isobutyraldehyde, benzaldehyde or substituted benzaldehydes, especially benzaldehydes substituted in the para position with an optionally branched alkyl group having 10 to 14 carbon atoms. Bisoxazolidines obtained by reacting OH-functional monooxazolidines with diisocyanates, especially hexamethylene 1,6-diisocyanate, are preferred. Suitable monooxazolidines are in particular obtained by reacting diethanolamine with aldehydes, with the release and removal of water.

[0077] Suitable aldimines are in particular the diamines or trialdimines obtained by reacting commercially available primary diamines or triamines with non-enolizable aldehydes, which are aldehydes that do not have a hydrogen atom in the alpha position relative to the carbon atom of the aldehyde group.

[0078] Particularly preferred blocked amines are N,N'-bis(2,2-dimethyl-3-lauroyloxypropylidene)hexylene-1,6-diamine, N,N'-bis(2,2-dimethyl-3-acetoxypropylidene)-3-aminomethyl-3,5,5-trimethylcyclohexylamine, N,N'-bis(2,2-dimethyl-3-lauroyloxypropylidene)-3-aminomethyl-3,5,5-trimethylcyclohexylamine, N,N'-bis(benzylidene)-3-aminomethyl-3,5,5-trimethylcyclohexylamine, N,N'-bis(4-C 10~14 -alkylbenzylidene)-3-aminomethyl-3,5,5-trimethylcyclohexylamine, average molecular weight M in the range of 450-750 g / mol nN,N'-bis(2,2-dimethyl-3-acetoxypropylidene)polyoxypropylenediamine having an average molecular weight M in the range of 750 to 1,050 g / mol n N,N'-bis(2,2-dimethyl-3-lauroyloxypropylidene)polyoxypropylenediamine having an average molecular weight M in the range of 380 to 680 g / mol n N,N'-bis(benzylidene)polyoxypropylenediamine having an average molecular weight M in the range of 680 to 1,100 g / mol n N,N'-bis(4-C 10~14 -alkylbenzylidene)polyoxypropylenediamine, average molecular weight M in the range of 730-880 g / mol n N,N',N''-tris(2,2-dimethyl-3-acetoxypropylidene)polyoxypropylenetriamine having an average molecular weight M in the range of 1,150 to 1,300 g / mol n N,N',N''-tris(2,2-dimethyl-3-lauroyloxypropylidene)polyoxypropylenetriamine having the formula:

[0079] Suitable catalysts are those that promote the reaction of isocyanate groups, especially organotin(IV) compounds, such as dibutyltin diacetate, dibutyltin dilaurate, dibutyltin dichloride, dibutyltin diacetylacetonate, dimethyltin dilaurate, dioctyltin diacetate, dioctyltin dilaurate, or dioctyltin diacetylacetonate, bismuth(III) or zirconium(IV) complexes with ligands selected from alkoxides, carboxylates, 1,3-diketonates, oxinates, 1,3-ketostearates, and 1,3-ketoamidates, or compounds containing tertiary amino groups, such as 2,2'-dimorpholinodiethyl ether (DMDEE). When the moisture-curable polyurethane composition contains blocked amines, suitable catalysts are also catalysts for the hydrolysis of blocked amino groups, especially organic acids, especially aromatic carboxylic acids such as benzoic acid, 2-nitrobenzoic acid, or salicylic acid. Also, combinations of different catalysts are particularly suitable.

[0080] Suitable stabilizers are in particular stabilizers against oxidation, heat, light or UV radiation. The composition preferably comprises at least one UV stabilizer.

[0081] The moisture-curable polyurethane composition may contain further additives, in particular - inorganic or organic pigments, in particular titanium dioxide, chromium oxide or iron oxide; fibres, in particular glass fibres, carbon fibres, metal fibres, ceramic fibres, polymer fibres such as polyamide fibres or polyethylene fibres or natural fibres such as wool, cellulose, hemp or sisal; - fillers such as graphene or carbon nanotubes; - dye; desiccants, in particular molecular sieve powders, calcium oxide, highly reactive isocyanates such as p-tosylisocyanate, monooxazolidines or orthoformates such as Incozol® 2 (Incorez); adhesion promoters, in particular organoalkoxysilanes, in particular epoxysilanes, such as in particular 3-glycidoxypropyltrimethoxysilane or 3-glycidoxypropyltriethoxysilane, (meth)acrylosilanes, silane anhydrides, carbamatosilanes, alkylsilanes or iminosilanes or oligomeric forms of these silanes or titanates; - further catalysts that accelerate the reaction of isocyanate groups; rheology modifiers, in particular thickeners, in particular layered silicates, such as bentonite, derivatives of castor oil, hydrogenated castor oil, polyamides, polyamide waxes, polyurethanes, urea compounds, fumed silica, cellulose ethers or hydrophobically modified polyoxyethylene; solvents, in particular acetone, methyl acetate, tert-butyl acetate, 1-methoxy-2-propyl acetate, ethyl 3-ethoxypropionate, diisopropyl ether, diethylene glycol diethyl ether, ethylene glycol diethyl ether, ethylene glycol monobutyl ether, ethylene glycol mono-2-ethylhexyl ether, acetals such as propylal, butyral, 2-ethylhexylal, dioxolane, glycerol formal or 2,5,7,10-tetraoxaundecane (TOU), toluene, xylene, heptane, octane, naphtha, white spirit, petroleum ether or gasoline, in particular Solvesso™ grades (Exxon), and propylene carbonate, dimethyl carbonate, butyrolactone, N-methylpyrrolidone, N-ethylpyrrolidone, p-chlorobenzotrifluoride or benzotrifluoride; natural resins, fats or oils, such as rosin, shellac, linseed oil, castor oil or soybean oil; - non-reactive polymers, in particular homo- or copolymers of unsaturated monomers, in particular ethylene, propylene, butylene, isobutylene, isoprene, vinyl acetate or alkyl (meth)acrylates, in particular polymers from the group comprising polyethylene (PE), polypropylene (PP), polyisobutylene, ethylene / vinyl acetate copolymer (EVA) or atactic poly-α-olefins (APAO); - flame retardant substances, in particular the above-mentioned fillers aluminum hydroxide or magnesium hydroxide or organic phosphates; additives, in particular wetting agents, levelling agents, antifoaming agents, degassing agents or biocides; or Further materials commonly used in moisture-curable polyurethane compositions may contain

[0082] It may be advisable to chemically or physically dry certain materials before incorporating them into the composition.

[0083] If the polymer containing isocyanate groups is mixed with further components of the composition, in particular fillers, the content of diisocyanate monomers can be further reduced by reacting with the moisture present.

[0084] The moisture-curable polyurethane composition preferably comprises: - 30% to 70% by weight of a polymer containing isocyanate groups, - 20% to 60% by weight of fillers, - 0% to 15% by weight, in particular 0% to 5% by weight, of a plasticizer, and Optionally, further components, especially blocked amines or catalysts Contains:

[0085] The moisture-curable polyurethane composition after curing has high strength combined with high elongation. The tensile strength, determined as described in the examples, is preferably at least 1.5 MPa, more preferably at least 2 MPa, and especially at least 3 MPa. The modulus, determined as described in the examples, in the range of 0.05 to 5% elongation, is preferably in the range of 2.5 to 20 MPa, especially 3 to 15 MPa. The elongation at break, determined as described in the examples, is preferably at least 300%, especially at least 500%.

[0086] The moisture-curable polyurethane composition is in particular prepared with the exclusion of moisture and stored at ambient temperature in a moisture-tight container. Suitable moisture-tight containers are in particular made of optionally coated metal and / or plastic, in particular drums, shipping boxes, shipping containers, buckets, canisters, cans, bags, tubular bags, cartridges or tubes.

[0087] The moisture-curable polyurethane composition may take the form of a one-component composition or a multi-component, especially a two-component, composition.

[0088] A composition referred to as a "one-component" composition is one in which all components of the composition are in the same container and are shelf stable as is.

[0089] Compositions referred to as "two-component" compositions are those in which the components of the composition are present in two different components stored in separate containers and are not mixed with each other until just before or at the time of application of the composition.

[0090] Moisture-curable polyurethane compositions are preferably one-component compositions, and when properly packaged and stored, are generally shelf stable for periods ranging from several months to over a year.

[0091] Once the moisture-curable polyurethane composition is applied, the curing process begins, resulting in a cured composition.

[0092] In the case of a one-component composition, it is applied as is and then begins to harden under the influence of moisture or water. To accelerate hardening, accelerator components containing or releasing water and / or catalysts and / or hardeners can be mixed into the composition at the time of application or can be contacted with the composition after its application.

[0093] During the curing process, isocyanate groups react with each other under the influence of moisture. If the moisture-curable polyurethane composition contains a blocked amine, the isocyanate groups, when hydrolyzed, further react with the blocked amino groups. The overall reaction of isocyanate groups, which results in curing of the composition, is also called crosslinking.

[0094] The moisture necessary for curing a moisture-curable polyurethane composition preferably enters the composition by diffusion from the air (atmospheric moisture). In the process, a solid layer of cured composition ("skin") forms on the surface of the composition that comes into contact with the air. Curing proceeds in a diffusional direction from the outside to the inside, and the skin gradually thickens until it eventually covers the entire applied composition. Moisture can also enter the composition further or entirely from one or more substrates to which the composition is applied, and / or can originate from accelerator components that are mixed into the composition during application or that come into contact with it after application, for example, by painting or spraying.

[0095] The moisture-curable polyurethane composition is preferably applied at ambient temperature, in the range of about −10 to 50° C., preferably −5 to 45° C., especially 0 to 40° C. The moisture-curable polyurethane composition is preferably cured at ambient temperature as well.

[0096] Moisture-curable polyurethane compositions have long processing times (open times) and rapid cure. When moisture-curable polyurethane compositions contain blocked amines, the aldehyde used to block the amino groups is released during the crosslinking process. If this is primarily nonvolatile, it remains in the cured composition to act as a plasticizer.

[0097] The moisture-curable polyurethane composition is preferably used as an elastic adhesive, or an elastic sealant, or an elastic coating.

[0098] The moisture-curing polyurethane compositions as adhesives and / or sealants are particularly suitable for joining and sealing applications in construction and manufacturing or in automotive assembly, in particular for parquet, joining assemblies, joining attachable parts, joining modules, joining glazings, sealing joints, sealing body structures, sealing seams or sealing cavities. Elastic joining in vehicle manufacturing is, for example, the adhesive attachment of parts such as plastic covers, trim strips, flanges, fenders, joining glazings into other parts or bodies attachable to the driver's cabin or the painted body of the vehicle, said vehicle being more particularly a car, truck, bus, train or ship.

[0099] Moisture-curing polyurethane compositions are particularly suitable as sealants for all kinds of joints, seams, or cavities, especially joints in construction, such as expansion joints or connecting joints made of structural components, especially plastics, floor joints in civil engineering, and elastic sealing. Flexible and highly flexible at low temperatures, these sealants are particularly suitable for sealing expansion joints in building structures. As coatings, moisture-curing polyurethane compositions are suitable for protecting and / or sealing architectural structures, especially in the field of plastic materials, especially balconies, terraces, roofs, especially flat or slightly sloped roof sections or roof gardens, or in damp rooms or building interiors under kitchen tiles or ceramic plates, drip pans, conduits, shafts, silos, tanks, or wastewater treatment systems. They can also be used for repair purposes, for example, as seals or coatings for leaking roof membranes or floor coverings that are no longer suitable for their purpose, or as repair compounds for highly reactive spray seals.

[0100] Moisture-curing polyurethane compositions can be formulated to have a paste-like consistency with structural viscosity. This type of composition is applied using a suitable device, such as a commercially available cartridge, barrel, or container, in the form of beads, which may have an essentially circular or triangular cross section. Moisture-curing polyurethane compositions are liquid and "self-leveling" or only slightly thixotropic, and can also be formulated so that they can be poured out for application. As a coating, it can then be evenly distributed to the desired layer thickness using, for example, a roller, a slide bar, a toothed applicator, or a trowel. In one operation, a layer thickness ranging from 0.5 to 3 mm, particularly from 1 to 2.5 mm, is typically applied.

[0101] The moisture-curable polyurethane composition is preferably used for bonding, sealing or coating at least one plastic substrate.

[0102] Suitable plastic substrates are in particular rigid and flexible PVC, polycarbonate, polystyrene, polyester, polyamide, PMMA, ABS, SAN, epoxy resins, phenolic resins, PUR, POM, TPO, PE, PP, EPM, EPDM or blends of polycarbonate with further plastics such as ABS and / or SAN, each of which may be in untreated form or in surface-treated form, for example treated with plasma, corona or flame, and may be fibre-reinforced plastics, such as in particular carbon fibre reinforced plastics (CFRP), glass fibre reinforced plastics (GFRP) or sheet moulding compounds (SMC).

[0103] Preferably, the plastic substrate is selected from the group consisting of rigid PVC, flexible PVC, polycarbonate, polystyrene, polyester, polyamide, PMMA, ABS, SAN, epoxy resins, phenolic resins, PUR, POM, TPO, PE, PP, EPM, EPDM, and blends of polycarbonate with further plastics, in particular ABS and / or SAN.

[0104] Among these, rigid PVC, polycarbonate, blends of polycarbonate with ABS and / or SAN, PMMA or ABS, especially polycarbonate or blends of polycarbonate, are preferred, as these plastics are particularly important for their good adhesion without complex pretreatment, especially when joining is frequently required.

[0105] Suitable further substrates which can be bonded or sealed or coated with the moisture-curable polyurethane composition are, in particular: - metals or alloys such as aluminium, copper, steel, non-ferrous metals, including surface-treated metals or alloys, for example zinc-plated or chrome-plated metals; - coated or painted substrates, in particular painted tiles, coated concrete, powder-coated metals or alloys or painted metal sheets; - paints or varnishes, especially automotive topcoats; - glass, glass ceramics, concrete, mortar, cement screed, fibre cement, in particular fibre cement board, brick, tile, gypsum, in particular gypsum board, or anhydrous screed, or natural stone such as granite or marble; - Repair or leveling compounds based on PCC (polymer-modified cement mortar) or ECC (epoxy resin-modified cement mortar); - Asphalt or bitumen; - Leather, textiles, paper, wood and wood materials bonded with resins such as phenolic, melamine or epoxy resins; further materials known as resin / textile composites or polymer composites; - Insulating foams, especially made of EPS, XPS, PUR, PIR, rock wool, glass wool or cellular glass is.

[0106] If necessary, the substrate can be pretreated before application, especially by physical and / or chemical cleaning methods or by application of an activator or primer.

[0107] It is possible to join and / or seal two of the same substrate or two different substrates.

[0108] The moisture-curable polyurethane composition is preferably used in a method of joining or sealing comprising the steps of: (i) combining a moisture-curable polyurethane composition described herein with - applying to a first substrate and contacting the composition with a second substrate within the open time of the composition; or - applied to a first and a second substrate and bonding the two substrates together within the open time of the composition; or - application between two substrates; (ii) curing the composition upon contact with moisture;

[0109] The moisture-curable polyurethane composition is also preferably used in a coating or sealing method comprising the steps of: (i) applying (spraying) a moisture-curable polyurethane composition described herein to a substrate; (ii) curing the composition upon contact with moisture;

[0110] In these methods, preferably at least one of the substrates is a plastic substrate, as described above.

[0111] Application (spreading) and curing of the moisture-curing polyurethane composition results in an article bonded, sealed or coated with the composition, which may be a building structure or part thereof, in particular a building structure in civil engineering above or below ground, a roof, a staircase or a facade, or an industrial or consumer product, in particular a window, a lamp, a traffic light, a household appliance or a means of transport, in particular a car, bus, caravan, truck, train, ship, aircraft or helicopter, or an attachable part thereof, such as a window, panoramic roof or lamp housing made of organic glass.

[0112] The present invention further provides a cured composition obtained from the moisture-curable polyurethane composition after contacting it with moisture.

[0113] The present invention further provides an adhesive bond comprising at least one plastic substrate and a composition cured by contact with moisture as described above.

[0114] Moisture-curable polyurethane compositions are characterized by their good storage stability when moisture is excluded, their rapid cure with long open times, and their outstanding elasticity after cure with high elongation, surprisingly high strength, and surprisingly good adhesion to plastic substrates, even when the compositions are formulated to have very low contents of diisocyanate monomers and therefore have an attractive EHS classification. [Example]

[0115] Examples are presented below and are intended to further illustrate the described invention. The invention is, of course, not limited to these described examples.

[0116] "Standard Climatic Conditions ("SCC")" means a temperature of 23±1°C and a relative air humidity of 50±5%. Unless otherwise specified, chemicals used were obtained from Sigma-Aldrich.

[0117] Viscosity was measured with a thermostated Rheotec RC30 cone-plate viscometer (cone diameter 25 mm, cone angle 1°, cone tip-plate distance 0.05 mm, shear rate 10 s -1 The diisocyanate monomer content was determined by HPLC (detection via photodiode array; 0.04 M sodium acetate / acetonitrile as mobile phase) before and after derivatization with n-propyl-4-nitrobenzylamine.

[0118] Polyols used: Acclaim® 4200: Polyoxypropylene diol, OH value 28 mg KOH / g (Covestro) Acclaim® 8200N: Polyoxypropylene diol, OH value 14 mg KOH / g (Covestro) Acclaim® 12200: Polyoxypropylene diol, OH value 10 mg KOH / g (Covestro) Desmophen® 5031BT: Ethylene oxide-terminated polyoxypropylene triol, OH value 28 mg KOH / g (Covestro) Voranol® CP4755: Ethylene oxide terminated polyoxypropylene triol, OH number 35.0 mg KOH / g (Dow).

[0119] Diisocyanate monomers used: Desmodur® 44MC L: diphenylmethane 44,4′-diisocyanate (Covestro) with an NCO content of 33.6% by weight.

[0120] Preparation of polymers containing isocyanate groups: Polymer L1 (linear): The reaction of 727 g of Acclaim® 4200 (0.36 equivalents of OH) and 273 g of Desmodur® 44MC L (2.18 equivalents of NCO) at 80°C by known methods yielded a polymer with an NCO content of 7.4 wt%, a viscosity of 5.2 Pa·s at 20°C, and a content of approximately 17 wt% diphenylmethane 4,4′-diisocyanate monomer. Subsequently, most of the volatile components, especially the diphenylmethane 4,4′-diisocyanate monomer, were removed by distillation in a short-path evaporator (jacket temperature 180°C, pressure 0.1-0.005 mbar, condensation temperature 47°C). The linear polymer thus obtained had an NCO content of 1.8 wt%, a viscosity of 13.3 Pa·s at 20°C, and a content of 0.08 wt% diphenylmethane 4,4′-diisocyanate monomer.

[0121] Polymer L2 (linear): An NCO-terminated polymer was prepared by reacting 400 g (0.20 equivalents of OH) of Acclaim® 4200 with 52 g (0.41 equivalents of NCO) of Desmodur® 44MC L at 80° C. by known methods. The linear polymer thus obtained had an NCO content of 1.8 wt %, a viscosity of 33 Pa·s at 20° C., and a diphenylmethane 4,4′-diisocyanate monomer content of approximately 2.5 wt %.

[0122] Polymer L3 (linear): The reaction of 757.7 g of Acclaim® 8200N (0.19 equivalents of OH) and 242.3 g of Desmodur® 44MC L (1.9 equivalents of NCO) at 80°C by known methods yielded a polymer with an NCO content of 7.2 wt%, a viscosity of 6.8 Pa·s at 20°C, and a diphenylmethane 4,4′-diisocyanate monomer content of approximately 20 wt%. Subsequently, most of the volatile components, especially the diphenylmethane 4,4′-diisocyanate monomer, were removed by distillation in a short-path evaporator (jacket temperature 180°C, pressure 0.1-0.005 mbar, condensation temperature 47°C). The linear polymer thus obtained had an NCO content of 1.0 wt%, a viscosity of 25.0 Pa·s at 20°C, and a diphenylmethane 4,4′-diisocyanate monomer content of 0.06 wt%.

[0123] Polymer L4 (linear): The reaction of 812.0 g of Acclaim® 12200N (0.15 equivalents of OH) and 188.0 g of Desmodur® 44MC L (1.5 equivalents of NCO) at 80°C by known methods yielded a polymer with an NCO content of 5.6 wt%, a viscosity of 13.9 Pa·s at 20°C, and a diphenylmethane 4,4′-diisocyanate monomer content of approximately 14 wt%. Subsequently, most of the volatile components, especially the diphenylmethane 4,4′-diisocyanate monomer, were removed by distillation in a short-path evaporator (jacket temperature 180°C, pressure 0.1-0.005 mbar, condensation temperature 47°C). The linear polymer thus obtained had an NCO content of 0.7 wt%, a viscosity of 29.4 Pa·s at 20°C, and a diphenylmethane 4,4′-diisocyanate monomer content of 0.04 wt%.

[0124] Polymer C1 (branched): The reaction of 725.0 g of Desmophen® 5031BT (0.36 equivalents of OH) and 275 g of Desmodur® 44MC L (2.2 equivalents of NCO) at 80°C by known methods yielded a polymer with an NCO content of 7.6 wt%, a viscosity of 6.5 Pa·s at 20°C, and a diphenylmethane 4,4′-diisocyanate monomer content of approximately 20 wt%. Subsequently, most of the volatile components, especially the diphenylmethane 4,4′-diisocyanate monomer, were removed by distillation in a short-path evaporator (jacket temperature 180°C, pressure 0.1-0.005 mbar, condensation temperature 47°C). The polymer thus obtained had an NCO content of 1.7 wt%, a viscosity of 19 Pa·s at 20°C, and a diphenylmethane 4,4′-diisocyanate monomer content of 0.04 wt%.

[0125] Polymer C2 (branched): By reacting 685 g of Voranol® CP4755, 115 g of Desmodur® 44MC L, and 200 g of diisodecyl phthalate at 80°C using a known method, a polymer with an NCO content of 2.0 wt. %, a viscosity of 55 Pa·s at 20°C, and a diphenylmethane 4,4′-diisocyanate monomer content of approximately 2.5 wt. % was obtained.

[0126] Moisture-curable polyurethane compositions: Compositions Z1~Z15: For each compound, the components specified in Tables 1 to 4 were mixed in the specified amounts (parts by weight) using a centrifugal mixer (SpeedMixer™ DAC 150, FlackTek Inc.) at 3000 rpm for 1 minute after excluding moisture, and the mixture was stored after excluding moisture. The compositions were tested as follows: The skin time (ST) was determined as a measure of the open time. For this purpose, a few grams of the composition were applied to a piece of cardboard in a layer approximately 2 mm thick, and the time was determined under standard climatic conditions after which an LDPE pipette used to gently tap the surface of the composition no longer left any residue.

[0127] The Shore A hardness was determined on test specimens cured for 14 days under standard climatic conditions in accordance with DIN 53505. To determine the mechanical properties, the compositions were applied to a silicone-coated release paper to obtain a 2 mm thick film, which was stored under standard climatic conditions for 14 days, and several dumbbells having a length of 75 mm with a bar length of 30 mm and a bar width of 4 mm were punched out of the film and these were tested for tensile strength (breaking force), elongation at break and 5% modulus (at elongation of 0.5 to 5%) according to DIN EN 53504 at a strain rate of 200 mm / min.

[0128] Adhesion to plastic substrates was determined by applying four parallel beads of the composition, each approximately 10 mm wide, 5 mm high, and 15 mm long, to each substrate and allowing them to cure for 7 days under standard climatic conditions. The cured composition's adhesion was then first tested by slitting the first bead at its narrow end directly above the joining surface, holding the cut end of the bead with round tweezers, and attempting to pull the bead away from the substrate. The bead was then re-slit downwards against the substrate, the detached portion was retracted with the round tweezers, and another attempt was made to detach the bead from the substrate. In this manner, the entire bead was excised by pulling it away from the substrate. Adhesion was then evaluated from the failure profile and reported in Tables 1, 2, or 3 under "7-Day SCC." A portion of the specimen was then immersed in deionized water for 7 days, then stored under standard climatic conditions for 2 hours, and then a second bead was detached from the substrate by pulling with round tweezers. Adhesion was evaluated from the failure profile and reported in Tables 1, 2, or 3 under "7-Day H2O." The specimens were then stored in an air circulating oven at 80°C for 24 hours, followed by two hours under standard climate conditions, and then a third bead was tested for adhesion as described and adhesion was assessed from the failure profile and reported in Tables 1, 2 or 3 under "1 day at 80°C". Finally, the specimens were stored at 70°C and 100% relative humidity for 7 days, followed by two hours under standard climate conditions, and a fourth bead was tested for adhesion as described and adhesion was assessed from the failure profile and reported in Tables 1, 2 or 3 under "7 days at 70°C / 100% relative humidity".

[0129] The plastic substrates used were the following plastic sheets (300 x 200 x 2 mm): PMMA: Plexiglas® XT 0A000 (Evonik Röhm) PC: Makrolon® GP clear099 (uncoated polycarbonate, Covestro) ABS:Metzoplast ABS / G(Metzeler Plastics GmbH) PVC: KoemaDur® ES (Koemmerling Kunststoffe) Adhesion was rated under the following scale: 100 represents greater than 95% cohesive failure, meaning very good adhesion. 70-90 indicates 70-90% cohesive failure, meaning good adhesion. 5 represents 5% cohesive failure, meaning poor adhesion. 0 represents 0% cohesive failure (100% adhesive failure), meaning poor adhesion.

[0130] The results are reported in Tables 1 to 4. Comparative examples are identified by (reference).

[0131] [Table 1]

[0132] [Table 2]

[0133] [Table 3]

[0134] [Table 4]

[0135] It is clear from Tables 1 to 4 that the compositions of the invention, in which the linear and branched polymers are present in the inventive ratio, show good mechanical properties and improved adhesion on plastic substrates compared to the respective reference compositions (Z1 / Z11 / Z15) in which the linear polymer content is too low, whereas the reference compositions (Z7 / Z14 / Z18) in which the linear polymer content is too high show good adhesion but have low tensile strengths which are undesirable for adhesives for elastic bonding. The present disclosure includes the following inventive aspects: <Aspect 1> 1. A moisture-curable polyurethane composition comprising: (i) at least one linear polymer P1 containing isocyanate groups and having an NCO content ranging from 0.3% to 3.3% by weight, obtained from the reaction of at least one aromatic diisocyanate monomer with a polyether diol having an OH value ranging from 5 to 37 mg KOH / g, (ii) at least one branched polymer P2 containing isocyanate groups and having an NCO content ranging from 1% to 10% by weight, obtained from the reaction of at least one aromatic diisocyanate monomer with at least one polyether triol having an average OH functionality ranging from at least 2.2 and an OH number ranging from 16 to 380 mg KOH / g, and (iii) a plasticizer content of 15% by weight or less based on the total composition; wherein the polymer P1 and the polymer P2 are present in a weight ratio ranging from 80 / 20 to 95 / 5; Moisture-curable polyurethane compositions. <Aspect 2> 2. The moisture-curable polyurethane composition according to embodiment 1, wherein polymer P1 has an NCO content in the range of 0.5% to 2.6% by weight. <Aspect 3> 3. The moisture-curable polyurethane composition of claim 1 or 2, wherein polymer P1 is prepared in such a way that the NCO / OH ratio in the reaction is at least 4 / 1, and the majority of the aromatic diisocyanate monomers are subsequently removed by a suitable separation process, so that the resulting polymer P1 containing isocyanate groups after distillation contains not more than 0.5 wt. % of diisocyanate monomers. <Aspect 4> 4. The moisture-curable polyurethane composition of any one of the preceding aspects, wherein the polyether diol has an OH number in the range of 6 to 33 mg KOH / g and an average OH functionality of at least 1.9. <Aspect 5> Aspect 5. The moisture-curable polyurethane composition of any one of aspects 1 to 4, wherein the aromatic diisocyanate monomer for both polymers P1 and P2 is diphenylmethane 4,4′-diisocyanate. <Aspect 6> 6. The moisture-curable polyurethane composition according to any one of aspects 1 to 5, wherein the total content of polymer P1 and polymer P2, based on the total composition, is in the range of 20% by weight to 80% by weight. <Aspect 7> 7. The moisture-curable polyurethane composition of any one of aspects 1 to 6, wherein the total content of diisocyanate monomers in the composition is less than 0.1 wt.%. <Aspect 8> 8. The moisture-curable polyurethane composition of any one of the preceding aspects, characterized in that at least one additional component is present selected from the group consisting of a filler, a diisocyanate oligomer, a blocked amine, a catalyst, and a stabilizer. <Aspect 9> 9. Use of the moisture-curable polyurethane composition according to any one of embodiments 1 to 8 as an elastic adhesive, or an elastic sealant, or an elastic coating. <Aspect 10> 10. The use according to aspect 9, characterized in that it is for bonding, sealing or coating at least one plastic substrate. <Aspect 11> 11. Use according to aspect 10, characterized in that the plastic substrate is selected from the group consisting of rigid PVC, flexible PVC, polycarbonate, polystyrene, polyester, polyamide, PMMA, ABS, SAN, epoxy resins, phenolic resins, PUR, POM, TPO, PE, PP, EPM, EPDM, and blends of polycarbonate with further plastics, in particular ABS and / or SAN. <Aspect 12> A method of joining or sealing, comprising the steps of: (i) a moisture-curable polyurethane composition according to any one of aspects 1 to 8, - applying to a first substrate and contacting the composition with a second substrate during the open time of the composition; or - applied to a first and a second substrate and bonding the two substrates together within the open time of the composition; or - application between two substrates, (ii) curing said composition upon contact with moisture. <Aspect 13> A method of coating or sealing comprising the steps of: (i) applying a moisture-curable polyurethane composition according to any one of embodiments 1 to 8 to a substrate; (ii) curing said composition upon contact with moisture. <Aspect 14> A cured composition obtained after contacting the moisture-curable polyurethane composition according to any one of embodiments 1 to 8 with moisture. <Aspect 15> A bonded composite comprising at least one plastic substrate and the polyurethane composition of any one of embodiments 1-8 cured by contact with moisture.

Claims

1. 1. A moisture-curable polyurethane composition comprising: (i) at least one aromatic diisocyanate monomer and an average molecular weight M of 3,500 g / mol to 18,000 g / mol having an OH number in the range of 5 to 30 mg KOH / g; ｎ at least one linear polymer P1 containing isocyanate groups and having an NCO content ranging from 0.3% to 3.3% by weight, obtained from the reaction of a polyether diol having the formula (ii) at least one branched polymer P2 containing isocyanate groups and having an NCO content in the range of 1% to 10% by weight, obtained from the reaction of at least one aromatic diisocyanate monomer with at least one polyether triol having an average OH functionality in the range of at least 2.2 and an OH number in the range of 16 to 380 mg KOH / g, and (iii) a plasticizer content of 15% by weight or less based on the total composition; wherein polymer P1 and polymer P2 are present in a weight ratio ranging from 84 / 16 to 95 / 5, Moisture-curable polyurethane compositions.

2. 2. Moisture-curable polyurethane composition according to claim 1, characterized in that the polymer P1 has an NCO content ranging from 0.5% to 2.6% by weight.

3. 3. The moisture-curable polyurethane composition according to claim 1, wherein the polymer P1 is prepared in such a way that the NCO / OH ratio in the reaction is at least 4 / 1, and the majority of the aromatic diisocyanate monomers are subsequently removed by a separation process which is a distillation method, so that the resulting polymer P1 containing isocyanate groups after distillation contains not more than 0.5% by weight of diisocyanate monomers.

4. 4. The moisture-curable polyurethane composition according to claim 1, wherein the polyether diol has an OH number in the range of 6 to 33 mg KOH / g and an average OH functionality of at least 1.

9.

5. Moisture-curable polyurethane composition according to any one of claims 1 to 4, characterized in that the aromatic diisocyanate monomer for both polymers P1 and P2 is diphenylmethane 4,4'-diisocyanate.

6. 6. The moisture-curable polyurethane composition according to claim 1, wherein the total content of polymer P1 and polymer P2, based on the total composition, is in the range of 20% to 80% by weight.

7. 7. The moisture-curable polyurethane composition according to any one of claims 1 to 6, wherein the content of diisocyanate monomers in the composition is less than 0.1% by weight in total.

8. 8. The moisture-curable polyurethane composition of claim 1, wherein at least one further component selected from the group consisting of fillers, diisocyanate oligomers, blocked amines, catalysts, and stabilizers is present.

9. Use of a moisture-curable polyurethane composition according to any one of claims 1 to 8 as an elastic adhesive, or an elastic sealant, or an elastic coating.

10. 10. Use according to claim 9, characterized in that it is for joining, sealing or coating at least one plastic substrate.

11. 11. Use according to claim 10, characterized in that the plastic substrate is selected from the group consisting of rigid PVC, flexible PVC, polycarbonate, polystyrene, polyester, polyamide, PMMA, ABS, SAN, epoxy resins, phenolic resins, PUR, POM, TPO, PE, PP, EPM, EPDM and blends of polycarbonate with further plastics.

12. A method of joining or sealing comprising the steps of: (i) a moisture-curable polyurethane composition according to any one of claims 1 to 8, - applied to a first substrate and contacting the composition with a second substrate within the open time of the composition; or - applied to a first and a second substrate and bonding the two substrates together within the open time of the composition; or - application between two substrates; (ii) curing the composition by contact with moisture.

13. A method of coating or sealing comprising the steps of: (i) applying a moisture-curable polyurethane composition according to any one of claims 1 to 8 to a substrate; (ii) curing the composition by contact with moisture.

14. A cured composition obtained after contacting the moisture-curable polyurethane composition of any one of claims 1 to 8 with moisture.

15. A bonded composite comprising at least one plastic substrate and the polyurethane composition of any one of claims 1 to 8 cured by contact with moisture.

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