High TG polyurethanes for HP-RTM

Abstract

Disclosed is a method for producing a molded polyurethane-polyisocyanurate-fiber composite part, the method comprising obtaining a reaction mixture by mixing: (A) an isocyanate-reactive component comprising: a polyol having an average functionality of 1.8 to 5.0 and a hydroxyl number of 200 to 500; and an alkali metal catalyst obtainable by introducing an alkali metal salt or an alkaline earth metal salt into a carbamate group-containing compound R-NH-CO-R ', where R is not hydrogen and / or is not COR' '; and (B) an isocyanate component comprising: at least one isocyanate compound, and a compound comprising one or more epoxy groups; and molding the reaction mixture at a temperature between 75 DEG C and 220 DEG C, at a pressure of 50 bar or more, to obtain the molded polyurethane-polyisocyanurate-fiber composite part.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to polyurethane formulations and systems for high pressure resin transfer molding (HP-RTM) applications, especially automotive applications. The systems and formulations of the present disclosure provide improved stability, higher temperature performance, overall high mechanical performance, high temperature stability and fast curing features with high glass transition temperatures exceeding 200°C. BACKGROUND

[0002] HP RTM is a process to produce composite materials by compression molding with resin injection at elevated temperature. Typically, a dry fiber preform is inserted into a mold and once the mold is closed and reaches a certain temperature, resin is injected at pressures up to 200 bar, thereby filling the mold and flowing through the entire preform.

[0003] Currently, in the automotive industry, composite materials with high temperature performance for EV battery and other applications are of interest. After such processes, the parts need to retain their mechanical performance and existing polyurethane molded parts are not suitable for those applications. In addition, the components must be stable enough to withstand storage for weeks or months. Therefore, there is a need for polyurethane systems with stable high temperature performance for such applications. SUMMARY

[0004] The present disclosure relates to a process for producing a polyurethane-polyisocyanurate-fiber composite part, the process comprising: obtaining a reaction mixture by mixing an isocyanate-reactive component with an isocyanate component, the isocyanate-reactive component comprising a polyol having an average functionality of 1.8 to 5.0 and a hydroxyl number of 200 to 500 and an alkali metal catalyst, which is obtainable by introducing an alkali metal salt or an alkaline earth metal salt into a compound R-NH-CO-R’ containing a urethane group, wherein R is not hydrogen and / or not COR”, the isocyanate component comprising at least one isocyanate compound and a compound containing one or more epoxy groups; and impregnating at least one fibrous reinforcing agent with the reaction mixture, preferably under pressure, to obtain a molded polyurethane-polyisocyanurate-fiber composite part. The present disclosure also relates to a polyurethane-polyisocyanurate-fiber composite part producible by such a process. BRIEF DESCRIPTION OF DRAWINGS

[0005] Figure 1A FTIR spectra of pure isocyanate, isocyanate / epoxide mixture at immediate mixing, 30 minutes after mixing and 14 days after mixing are shown; b) pure isocyanate and isocyanate / epoxide mixture after 50 days.

[0006] Figure 1BFTIR spectra of pure isocyanate and isocyanate / epoxide mixture after 50 days are shown.

[0007] Figure 2 A graph showing NCO content of exemplary compositions (diamonds) compared to a control formulation (triangles) is shown.

[0008] Figure 3 A graph showing gel time aging of exemplary compositions is shown.

[0009] Figure 4A DMA of Tg stability of exemplary compositions after 48 hours is shown.

[0010] Figure 4B DMA of Tg stability of exemplary compositions after 4 months is shown. Figure 4A

[0011] Figure 5 A graph showing flexural modulus of exemplary compositions over 180 days is shown.

[0012] Figure 6 A graph showing flexural strength of exemplary compositions over 180 days is shown. DETAILED DESCRIPTION

[0013] The present disclosure relates to a unique polyurethane formulation and system that includes a two-part catalyst that includes an alkali metal catalyst and a compound containing one or more epoxy groups, the alkali metal catalyst is obtainable by introducing an alkali metal salt or an alkaline earth metal salt into a compound containing a carbamate group, R-NH-CO-R’, wherein R is not hydrogen and / or is not COR”. It was surprisingly found that the alkali metal catalyst can side destabilize isocyanate and can cure isocyanate after a short time (weeks to months). The inventors found that including an alkali metal catalyst on the isocyanate reactive side and including a compound containing one or more epoxy groups on the isocyanate side can provide improved stability and long-term storage while also providing excellent physical properties.

[0014] The formulations and methods described herein provide the following advantages:

[0015] - high glass transition, thus maintaining mechanical properties at elevated temperatures. For example, the polyurethane formulations and systems of the present disclosure advantageously allow for the production of composite parts containing up to 80% glass fiber while having a glass transition above up to 230°C and without glass fiber up to 275°C. In contrast, conventional formulations typically have a maximum glass transition at about 150°C and are more costly.

[0016] ​- allows the automotive industry to embed parts made from the formulation into the body of a car and to subject them to an electrocoating process at high temperature for at least 20 minutes.

[0017] - allows to manufacture parts used in the vicinity of exhaust devices and to replace metal parts.

[0018] - allows to use in battery trays, where all materials need to perform at high temperatures in case of fire.

[0019] - the reactivity and the thermo-mechanical properties of the system for the manufacture of molded parts remain stable for more than 6 months.

[0020] The present disclosure provides a process for producing a molded polyurethane-polyisocyanurate-fiber composite part, the process comprising obtaining a reaction mixture by mixing:

[0021] an isocyanate-reactive component, the isocyanate-reactive component comprising:

[0022] a polyol having an average functionality of 1.8 to 5.0 and a hydroxyl number of 200 to 500, and

[0023] an alkali metal catalyst, the alkali metal catalyst being obtainable by introducing an alkali metal salt or an alkaline earth metal salt into a compound R-NH-CO-R’ containing a urethane group, wherein R is not hydrogen and / or not COR”;

[0024] an isocyanate component, the isocyanate component comprising:

[0025] at least one isocyanate compound, and

[0026] a compound containing one or more epoxy groups; and

[0027] molding the reaction mixture at a temperature between 75 °C and 220 °C under a pressure of 50 bar or more to obtain the molded polyurethane-polyisocyanurate-fiber composite part.

[0028] A. Isocyanate Component

[0029] The isocyanate component can comprise at least one isocyanate compound, such as a polyisocyanate and a compound containing one or more epoxy groups.

[0030] 1. Isocyanate Compound

[0031] Suitable isocyanates (which can also be referred to herein as polyisocyanates) encompass all aliphatic, cycloaliphatic and aromatic isocyanates known for the preparation of polyurethanes. They preferably have an average functionality of less than 2.5. Examples include 2,2'-, 2,4'- and 4,4'-diphenylmethane diisocyanate, mixtures of monomeric diphenylmethane diisocyanate with higher polycyclic homologues of diphenylmethane diisocyanate (polymeric MDI), isophorone diisocyanate (IPDI) or oligomers thereof, 2,4- or 2,6-toluene diisocyanate (TDI) or mixtures thereof, tetramethylene diisocyanate or oligomers thereof, hexamethylene diisocyanate (HDI) or oligomers thereof, naphthylene diisocyanate (NDI), or mixtures thereof.

[0032] As polyisocyanate, it is preferred to use monomeric diphenylmethane diisocyanate, such as 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate or mixtures thereof. Here, the diphenylmethane diisocyanates can also be used as mixtures with derivatives thereof. In this case, the diphenylmethane diisocyanates can particularly preferably contain up to 10% by weight, further particularly preferably up to 5% by weight, of carbodiimide-, uretdione- or uretonimine-modified diphenylmethane diisocyanates, in particular carbodiimide-modified diphenylmethane diisocyanates.

[0033] The polyisocyanates can also be used in the form of polyisocyanate prepolymers. These polyisocyanate prepolymers can be obtained by reacting an excess of the above-mentioned polyisocyanates with one or more polyols at a temperature of, for example, from 30°C to 100°C, preferably about 80°C, to give prepolymers.

[0034] The NCO content of the polyisocyanate prepolymers is preferably from 5% to 33% by weight NCO, more preferably from 15% to 28% by weight NCO. Suitable polyisocyanate prepolymers can include, for example, those described in U.S. Patent No. 3,883,571, WO 02 / 10250 and U.S. Patent No. 4,229,347, each of which is incorporated herein by reference in its entirety.

[0035] Polyols are known to those skilled in the art and are described, for example, in “Kunststoffhandbuch, 7, Polyurethane”, Carl Hanser-Verlag, 3rd edition 1993, section 3.1. As polyols, it is possible, for example, to use polyetherols or polyesterols. Preferred polyols comprise secondary OH groups, such as polypropylene oxide. These polyols preferably have a functionality of from 2 to 6, more preferably from 2 to 4 and more particularly from 2 to 3. Particularly preferably, the polyols comprise polyesterols containing hydrophobic substances, as described below.

[0036] Particularly preferably used as polyisocyanate is diphenylmethane diisocyanate or a polyisocyanate prepolymer based on monomeric 4,4'-diphenylmethane diisocyanate or a mixture of 4,4'-diphenylmethane diisocyanate and its derivatives and polypropylene oxide having a functionality of 2 to 4 and optionally dipropylene glycol or monomeric polyisocyanate prepolymers.

[0037] Optionally, a chain extender may be added to the reaction to form a polyisocyanate prepolymer. Suitable chain extenders for the prepolymer are dihydric or trihydric alcohols, examples being dipropylene glycol and / or tripropylene glycol, or adducts of dipropylene glycol and / or tripropylene glycol with an alkylene oxide, preferably dipropylene glycol.

[0038] 2. Compound Containing One or More Epoxy Groups

[0039] Compounds containing one or more epoxy groups include compounds containing one, two, three or more epoxy groups per molecule and may be epoxy resins. Suitable compounds containing one or more epoxy groups may include monofunctional or polyfunctional oxiranes. Examples of monofunctional compounds containing one or more epoxy groups are, for example, glycidyl ethers of aliphatic and alicyclic monohydroxy compounds, typically having 2 to 20 carbon atoms, or ethylhexyl glycidyl ether and glycidyl esters of aliphatic or alicyclic monocarboxylic acids, typically having 2 to 20 carbon atoms. The epoxide functionality, i.e. the number of epoxy groups per molecule, is typically 1 to 3, in particular in the range of 1.2 to 2.5. Particularly preferred are glycidyl ethers of aliphatic or alicyclic alcohols, preferably having 1, 2, 3 or 4 OH groups and 2 to 20 or 4 to 20 C atoms, and glycidyl ethers of aliphatic polyether alcohols, preferably having 4 to 20 C atoms. Suitable examples include:

[0040] Glycidyl ethers of saturated alkanols having 2 to 20 C atoms, for example C2-C20-alkyl glycidyl ethers, such as 2-ethylhexyl glycidyl ether;

[0041] Glycidyl ethers of saturated alkane polyols having 2 to 20 carbon atoms, such as glycidyl ethers of 1,4-butanediol, 1,6-hexanediol, trimethylolpropane or pentaerythritol, wherein the above-mentioned glycidyl ether compounds generally have an epoxy functionality in the range of 1 to 3.0 and preferably in the range of 1, 2 to 2.5; glycidyl ethers of polyether alcohols having 4 to 20 carbon atoms, such as glycidyl ethers of diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol or tripropylene glycol;

[0042] Glycidyl ethers of cycloaliphatic alcohols having 5 to 20 C atoms, for example bisglycidyl ether of cyclohexane-1,4-diyl, bisglycidyl ether of cyclic hydrogenated bisphenol A or bisphenol F,

[0043] glycidyl ethers of polyalkylene oxides having 2 to 4 carbon atoms, such as polyethylene oxide or polypropylene oxide;

[0044] and mixtures of the aforementioned substances.

[0045] The compound containing one or more epoxy groups is preferably liquid at 25 °C. Mixtures of such compounds, which are also preferably liquid at 25 °C, can also be used.

[0046] In some aspects, the compound containing one or more epoxy groups can be used in an amount such that the equivalent ratio of epoxy groups to isocyanate groups in the isocyanate component is 0.1 to 2.0, more preferably 0.25 to 1.75, or more preferably 0.5 to 1.5.

[0047] The compound containing one or more epoxy groups can preferably include one or more epoxy diluents. Commercially available examples suitable for use as epoxy diluents for the compound containing one or more epoxy groups include Araldite DY-E from Huntsman and DER 721 from Olin.

[0048] The compound containing one or more epoxy groups is preferably used in an amount of 0.3 to 15 wt.%, preferably 0.5 to 10 wt.%, more particularly 0.8 to 5 wt.%, based on the total weight of the compound containing one or more epoxy groups and the isocyanate compound.

[0049] B. Isocyanate-Reactive Component

[0050] The isocyanate-reactive component includes reactive components such as polyols having an average functionality of 1.8 to 5.0 and a hydroxyl number of 200 to 500, and an alkali metal catalyst, which is obtainable by introducing an alkali metal salt or an alkaline earth metal salt into a compound containing a urethane group R-NH-CO-R’, wherein R is not hydrogen and / or not COR”.

[0051] 1. Alkali Metal Catalyst

[0052] The alkali metal catalyst is a mixture obtainable by introducing an alkali metal salt or an alkaline earth metal salt into a compound comprising a urethane group. The alkali metal catalyst used herein is a compound that reacts with the compound containing one or more epoxy groups to chemically form an active species at high temperatures (> 75 °C) resulting in a PU / PIR reaction mechanism.

[0053] Specifically, the alkali metal salt or alkaline earth metal salt compounds of the alkali metal catalyst include sodium, lithium, magnesium and potassium, as well as ammonium compounds, preferably salts of lithium or magnesium with any desired anion, preferably with anions of organic acids, such as carboxylates, and more preferably with anions of inorganic acids, such as nitrates, halides, sulfates, sulfites and phosphates, still more preferably with anions of monobasic acids, such as nitrates or halides, especially nitrates, chlorides, bromides or iodides. Particularly preferred is the use of lithium chloride, lithium bromide and magnesium dichloride, especially lithium chloride. The alkali metal or alkaline earth metal salts of the present application can be used individually or as a mixture.

[0054] The compounds comprising urethane groups are to be understood as any desired compounds which are liquid or solid at 20°C and comprise at least one urethane group R-NH-CO-R', wherein R is not hydrogen and / or is not COR". In the alkali metal catalyst, the compounds comprising urethane groups are here preferably obtainable by the reaction of a polyisocyanate with a compound having at least one OH group, preferably at least two OH groups. The polyisocyanate can be the same or different from the polyisocyanate used as the at least one isocyanate compound. For example, a first polyisocyanate can be used as the at least one isocyanate compound, and the compounds comprising urethane groups in the alkali metal catalyst can be the reaction product of a second polyisocyanate with a compound having OH groups.

[0055] Preferred here are compounds which are liquid at 50°C, and more preferably those which are liquid at room temperature. A substance or component is referred to as "liquid" in the context of the present application if it has a viscosity of not more than 10 Pas at the stated temperature. In the absence of a stated temperature, the data are based on 20°C. In this context, the measurement is carried out in accordance with ASTM D445-11.

[0056] The compounds comprising urethane groups preferably have at least two urethane groups. The molecular weight of these compounds comprising urethane groups is preferably in the range from 200 g / mol to 15000 g / mol, more preferably from 300 g / mol to 10000 g / mol and more particularly from 500 g / mol to 1300 g / mol. The compounds comprising urethane groups can be obtained, for example, by reaction of the above-mentioned isocyanates as second isocyanates with compounds having at least one hydrogen atom which is reactive towards isocyanates, such as alcohols, examples being monohydric alcohols, such as methanol, ethanol, propanol, butanol, pentanol, hexanol, or longer-chain propoxylated or ethoxylated monohydric alcohols, such as poly(ethylene oxide) monomethyl ether, such as, for example, the monofunctional Products, diols, such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, butylene glycol, hexylene glycol, and / or reaction products of the isocyanates with the following polyols and / or chain extenders (alone or in mixtures).

[0057] To prepare compounds comprising urethane groups, not only isocyanates, but also polyols in stoichiometric excess can be used. In the case of the use of monohydric alcohols, isocyanate groups and OH groups can also be used in stoichiometric ratio. When the compounds comprising urethane groups have two or more isocyanate groups per molecule, they can be replaced in whole or in part by polyisocyanates.

[0058] The reaction can generally be carried out at temperatures between 20 °C and 120 °C, for example at 80 °C. The second isocyanate for preparing the compounds comprising urethane groups is preferably an isomer or homolog of diphenylmethane diisocyanate. More preferably, the second isocyanate is a monomeric diphenylmethane diisocyanate, for example 2,2’-diphenylmethane diisocyanate, 2,4’-diphenylmethane diisocyanate, 4,4’-diphenylmethane diisocyanate or mixtures thereof. The diphenylmethane diisocyanate can also be used as a mixture with derivatives thereof. In this case, the diphenylmethane diisocyanate can particularly preferably contain up to 10 % by weight, further particularly preferably up to 5 % by weight, of carbodiimide-, uretdione- or isocyanatoimine-modified diphenylmethane diisocyanates, in particular carbodiimide-modified diphenylmethane diisocyanates. In a particularly preferred embodiment, the first isocyanate and the second isocyanate for preparing the compounds comprising urethane groups are identical.

[0059] The compounds comprising urethane groups can also be obtained by alternative reaction pathways, for example by reacting carbonates with monamines to form urethane groups. To this end, for example, a slight excess (1.1 equivalents) of propylene glycol carbonate is reacted with a monamine, for example M 600 at 100 °C. The resulting urethanes can likewise be used as compounds comprising urethane groups.

[0060] The mixture comprising the alkali metal or alkaline earth metal salt and the compound comprising a urethane group can be obtained, for example, by mixing the alkali metal or alkaline earth metal salt into the compound comprising a urethane group at room temperature or at elevated temperatures above room temperature. This can be done using any mixer, such as a single stirrer. In this case, the alkali metal or alkaline earth metal salt can be used as a pure substance or in the form of a solution in a monofunctional or polyfunctional alcohol, for example such as methanol, ethanol, or a chain extender or water. In a particularly preferred embodiment, a commercially available isocyanate based on a prepolymer is mixed directly with the dissolved salt. Suitable for this purpose, for example, are isocyanate prepolymers with an NCO content of 15% to 30%, which are based in particular on diphenylmethane diisocyanate and polyether polyols. Such isocyanates are available, for example, under the trade name MP 102 is commercially available from BASF.

[0061] In a particularly preferred embodiment of the application, the alkali metal or alkaline earth metal salt is dissolved in a compound having hydrogen atoms which are reactive towards isocyanates, and the solution is subsequently mixed with the isocyanate, optionally at elevated temperature.

[0062] It is particularly preferred that the compound comprising a urethane group is prepared using a monohydric alcohol having a molecular weight of 30 g / mol to 15 000 g / mol, preferably 100 g / mol to 900 g / mol, and in a particularly preferred variant 400 g / mol to 600 g / mol.

[0063] In each case, the amount of alkali metal or alkaline earth metal ions per urethane group in the alkali metal catalyst is 0.0001 to 3.5, preferably 0.01 to 1.0, more preferably 0.05 to 0.9, and more particularly 0.1 to 0.8, based on the number of alkali metal or alkaline earth metal ions and urethane groups (per equivalent of urethane group).

[0064] In each case, the amount of alkali metal or alkaline earth metal ions per isocyanate group in the isocyanate component and, if present, in the alkali metal catalyst, is preferably 0.0001 to 0.3, more preferably 0.0005 to 0.02, and more particularly 0.001 to 0.01 equivalents, based on the number of alkali metal or alkaline earth metal ions and isocyanate groups.

[0065] In each case, the amount of alkali metal or alkaline earth metal ions per epoxy group of the compound containing one or more epoxy groups is preferably greater than 0.00001, and more preferably 0.00005 to 0.3, based on the number of alkali metal or alkaline earth metal ions and epoxy groups.

[0066] A thermoreversible interaction between the alkali metal or alkaline earth metal salt in the alkali metal catalyst and the compound comprising a urethane group is preferably present at 25°C, while the catalytically active compound is in free form at temperatures above 50°C, preferably from 60°C to 200°C and more particularly from 80°C to 200°C. For the purposes of the present disclosure, a thermoreversible interaction is assumed to be present when the open time of the reaction mixture at 25°C is at least 5 times, more preferably at least 10 times and more particularly at least 20 times as long as at 80°C. The open time is defined here as the time until the viscosity of the reaction mixture at constant temperature increases to such an extent that the required stirring force exceeds the given stirring force of a Schyodu gel timer (model 100, version 2012). To this end, in each case 200 g of the reaction mixture are prepared, mixed in a Speedmixer at 1950 rpm for 1 minute and stirred in an oven at room temperature or at an elevated reaction temperature using a Schyodu gel timer (model 100, version 2012) and the associated wire mesh stirrer at 20 rpm with 130 g of the mixture in a PP beaker with a diameter of 7 cm until the viscosity and thus the required stirring force of the reaction mixture exceeds the stirring force of the gel timer.

[0067] 2. Polyol

[0068] The isocyanate-reactive component comprises a polyol, such as a polyol having an average functionality of from 1.8 to 5.0 and a hydroxyl number of from 200 to 500.

[0069] As polyetherols having an average functionality of from 1.8 to 5.0, preferably from 1.9 to 4.8 and more preferably from 1.95 to 4.4, and a hydroxyl number of from 200 to 500, preferably from 250 to 450 and more particularly from 300 to 400 mg KOH / g, conventional polyetherols having these parameters can be used. As isocyanate-reactive groups, groups such as OH, SH and NH groups can be present. The polyol preferably has essentially OH groups, more preferably only OH groups as isocyanate-reactive groups.

[0070] In a preferred embodiment, the polyol has at least 40%, preferably at least 60%, more preferably at least 80% and more particularly at least 95% of secondary OH groups, based on the number of isocyanate-reactive groups. In another preferred embodiment, the polyol has at least 60%, more preferably at least 80% and more particularly at least 95% of primary OH groups, based on the number of isocyanate-reactive groups. Here, the calculation of the average OH number and the average functionality is based on all polyetherols used.

[0071] The polyetherols are obtained by known methods in the presence of a catalyst, for example by anionic polymerization of alkylene oxides, with the addition of at least one starter molecule which comprises 2 to 4, preferably 2 to 3 and more preferably 2 reactive hydrogen atoms in bound form. The catalysts used can be alkali metal hydroxides, such as sodium hydroxide or potassium hydroxide, or alkali metal alkoxides, such as sodium methylate, sodium ethylate or potassium ethylate or potassium isopropylate, or in the case of cationic polymerization, Lewis acids, such as antimony pentachloride, boron trifluoride in diethyl ether or bleaching earth are used as catalysts. As catalyst, in addition, double metal cyanide compounds, known as DMC catalysts, can be used. For polyetherols with a hydroxyl number > 200 mg KOH / g, tertiary amines, such as imidazole, can also be used as catalyst. Such polyols are described in WO 2011 / 107367, the entire contents of which are incorporated herein by reference.

[0072] As alkylene oxide, one or more compounds having 2 to 4 carbon atoms in the alkylene group are preferably used, such as tetrahydrofuran, 1,2-epoxypropane or 1,2- and / or 2,3-epoxybutane, in each case individually or in mixtures, and 1,2-epoxypropane, 1,2-epoxybutane and / or 2,3-epoxybutane, especially 1,2-epoxypropane, are preferably used.

[0073] The starter molecules considered include, for example, ethylene glycol, diethylene glycol, glycerol, trimethylolpropane, pentaerythritol, sucrose, methylamine, ethylamine, isopropylamine, butylamine, benzylamine, aniline, toluidine, toluenediamine, naphthylamine, ethylenediamine, diethanolamine, triethanolamine and other starter molecules, especially diols.

[0074] C. Fibrous Reinforcing Agent

[0075] The fibrous reinforcing agent can be fibers, such as glass fibers, aramid fibers, carbon fibers or fibers made of plastic. Reinforcing agents of these kinds are known and are generally used for the production of fiber-reinforced plastics. The fibrous reinforcing agent is preferably used in the form of a ply. Such fiber plies are obtained, for example, by joining individual fibers together. In a preferred embodiment, the fibrous reinforcing agent consists of a unidirectional scrim, a woven fabric or a knitted fabric based on glass fibers, aramid fibers, carbon fibers or fibers made of plastic. Reinforcing agent plies of these types are known and are commercially available. In particular, glass fiber mats are employed.

[0076] In some aspects, the at least one fibrous reinforcing agent can be used in an amount in the range of 25% to 80% by weight of the reaction mixture comprising the isocyanate-reactive components and the isocyanate components. More preferably, the at least one fibrous reinforcing agent can be used in an amount in the range of 30% to 75% by weight of the reaction mixture, or 35% to 70% by weight of the reaction mixture.

[0077] D. Additional Components

[0078] Either or both of the isocyanate-reactive component or the isocyanate component can comprise one or more additional components as desired. In order to vary the mechanical properties, such as the hardness, it can prove advantageous to add chain extenders, crosslinkers or optionally mixtures of these. In the case of production of composites, chain extenders can be used. However, it is also possible to use no chain extenders.

[0079] When low-molecular-weight chain extenders are used, known chain extenders related to polyurethane production can be used. These are preferably aliphatic and cycloaliphatic and / or araliphatic or aromatic diols and optionally triols having 2 to 14, preferably 2 to 10, carbon atoms, such as ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 1,10-decanediol and bis(2-hydroxyethyl)hydroquinone, 1,2-, 1,3- and 1,4-dihydroxy cyclohexane, diethylene glycol, dipropylene glycol, tripropylene glycol, triols such as 1,2,4- and 1,3,5-trihydroxy cyclohexane, glycerol and trimethylolpropane.

[0080] Preferably, in addition to the polyols of the isocyanate-reactive component and the chain extenders, less than 50% by weight, particularly preferably less than 30% by weight, more preferably less than 10% by weight, of additional compounds having isocyanate-reactive hydrogen atoms, in particular no additional compounds, such as polyester or polycarbonate diols, are used, based on the total weight of the polyols, chain extenders and further compounds having isocyanate-reactive hydrogen atoms of the isocyanate-reactive component.

[0081] Furthermore, water-absorbing additives can be used. The preferred water-absorbing additives used are aluminosilicates selected from the group comprising sodium aluminosilicate, potassium aluminosilicate, calcium aluminosilicate, cesium aluminosilicate, barium aluminosilicate, magnesium aluminosilicate, strontium aluminosilicate, sodium aluminophosphate, potassium aluminophosphate, calcium aluminophosphate, and mixtures thereof. It is particularly preferred that a mixture of sodium aluminosilicate, potassium aluminosilicate and calcium aluminosilicate in castor oil carrier is used.

[0082] The water-absorbing additives preferably have an average particle size of not more than 200 pm, more preferably not more than 150 pm and in particular not more than 100 pm. The pore size of the water-absorbing additives of the present application is preferably 2 to 5 angstroms. In addition to inorganic water-absorbing additives, known organic water-absorbing additives can also be used, such as orthoformates, an example being triisopropyl orthoformate.

[0083] If water-absorbing additives are added, their amount is preferably greater than 1 part by weight, more preferably in the range from 1.2 to 2 parts by weight, based on the total weight of the polyisocyanurate system.

[0084] The polyurethane system preferably comprises less than 0.5 wt.-%, more preferably less than 0.3 wt.-% of water, based on the total weight of the components of the reaction mixture.

[0085] If a polyurethane foam is to be prepared, instead of the water scavenger, also chemical and / or physical blowing agents commonly used in polyurethane chemistry can be used. Chemical blowing agents are to be understood as compounds which form gaseous products due to a reaction with isocyanates, such as, for example, water or formic acid. Physical blowing agents are to be understood as compounds which are present in solution or emulsion in the ingredients for the preparation of the polyurethane and which evaporate under the conditions of the polyurethane formation. Examples are hydrocarbons, halogenated hydrocarbons and other compounds such as, for example, perfluoroalkanes such as perfluorohexane, fluorochlorocarbons and ethers, esters, ketones, acetals or mixtures thereof, for example (cyclo)aliphatic hydrocarbons having 4 to 8 carbon atoms, or hydrofluorocarbons such as HFC-365mfc from Solvay Fluoride LLC. 365. Preferably no blowing agent is added.

[0086] The flame retardants which can be used are generally known from the prior art. Examples of suitable flame retardants are brominated ethers (Ixol B 251), brominated alcohols such as dibromoneopentyl alcohol, tribromoneopentyl alcohol and PHT-4 diol, and chlorinated phosphates such as, for example, tris(2-chloroethyl)phosphate, tris(2-chloroisopropyl)phosphate (TCPP), tris(1,3-dichloroisopropyl)phosphate, tris(2,3-dibromopropyl)phosphate and tetrakis(2-chloroethyl)ethylene diphosphate, or mixtures thereof.

[0087] In addition to the halogen-substituted phosphates already mentioned, inorganic flame retardants such as red phosphorus, preparations containing red phosphorus, expandable graphite, aluminium oxide hydrate, antimony trioxide, arsenic oxide, ammonium polyphosphate and calcium sulphate, or cyanuric acid derivatives such as melamine, or mixtures of at least two flame retardants, such as ammonium polyphosphate and melamine, and optionally starch, can also be used to impart flame retardancy to the rigid polyurethane foam prepared according to the application.

[0088] As further liquid halogen-free flame retardants, diethyl ethanephosphonate (DEEP), triethyl phosphate (TEP), dimethyl propylphosphonate (DMPP), diphenyl toluene phosphate (DPK) and the like can be used.

[0089] In the context of the present application, the flame retardants are preferably used in an amount of 0 to 60 wt.-%, more preferably 5 to 50 wt.-%, more particularly 5 to 40 wt.-%, based on the total weight of components (b) to (e).

[0090] Useful internal release agents are all release agents commonly used in the production of polyurethanes, examples being metal salts in diamine solution, such as zinc stearate, and derivatives of polyisobutylene succinic acid. Additional additives commonly used in polyurethane chemistry, such as stabilizers, UV absorbers or antioxidants, can also be used.

[0091] E. Polyurethane Systems and Methods

[0092] The molded polyurethane-polyisocyanurate-fiber composite part can be prepared by mixing the isocyanate-reactive component and the isocyanate component and optionally additional components to form a reaction mixture, applying the reaction mixture to the fibrous reinforcement to impregnate the fibrous reinforcement, passing the impregnated fibrous reinforcement under pressure through a die or mold, and completing the reaction to obtain the polyurethane-polyisocyanurate-fiber composite part. The reaction mixture can be molded at a temperature of 75°C to 220°C under a pressure of 50 bar or more to obtain the molded polyurethane-polyisocyanurate-fiber composite part.

[0093] Here, for the purposes of the present invention, the mixture of the isocyanate-reactive component and the isocyanate component is referred to as a reaction mixture having a reaction conversion of less than 90% based on isocyanate groups. The individual components can have been pre-mixed. The isocyanate-reactive component and the isocyanate component can be mixed in a ratio of about 1 :3, for example, a ratio of about 1 : 10 to a ratio of about 1 : 1.

[0094] The isocyanate-reactive component and the isocyanate component can be mixed at room temperature, but can also be mixed at elevated temperature. The reaction mixture is a temperature-activated formulation and it has a long shelf life of more than 10 hours at room temperature after mixing. The activation temperature is about 75-85°C.

[0095] The reaction mixture has a long open time at 25°C, for example more than 60 minutes, preferably more than 90 minutes and more preferably more than 120 minutes. As mentioned above, the open time here is determined by the increase in viscosity. Raising the temperature to a temperature of more than 60°C, preferably 70°C to 120°C, more preferably 70°C to 100°C and especially 75°C to 95°C, causes the reaction mixture of the present invention to cure quickly, for example in less than 50 minutes, preferably less than 30 minutes, more preferably less than 20 minutes and more particularly less than 10 minutes. For the purposes of the present disclosure, the curing of the reaction mixture means an increase in viscosity of a factor of ten from the initial viscosity. Here, the difference between the open time at 25°C and the open time at 80°C is preferably at least 40 minutes, more preferably at least 1 hour and very preferably at least 2 hours.

[0096] The isocyanate index of the inventive process is in the range of 100 to 450, preferably 125 to 425, more preferably 150 to 400, very preferably 175 to 375 and more particularly 200 to 350. In the context of the present invention, the isocyanate index refers to the stoichiometric ratio of isocyanate groups to isocyanate reactive groups multiplied by 100. Isocyanate reactive groups are all groups which react with isocyanates present in the reaction mixture, including chemical blowing agents and compounds having epoxy groups, but not the isocyanate groups themselves.

[0097] In some aspects of the present disclosure, preferably, a dense material is obtained; in other words, no blowing agent is added. Small amounts of blowing agents, for example small amounts of water condensed into the reaction mixture or starting components by atmospheric humidity during processing, are not included in the previous statement. A dense polyurethane-polyisocyanurate-fiber composite part refers to a polyurethane-polyisocyanurate-fiber composite part which is essentially free of gaseous inclusions. The density of the dense polyurethane-polyisocyanurate-fiber composite part is preferably greater than 0.8 g / cm3 3 , more preferably greater than 0.9 g / cm3 3 , and more particularly greater than 1.0 g / cm3 3 .

[0098] In addition to the alkali metal or alkaline earth metal salt used in the alkali metal catalyst, the formulation can not include the compounds used in the inventive process for accelerating the isocyanate-polyol reaction, such as the customary polyurethane catalysts based on compounds having tertiary amine groups. The polyurethane-polyisocyanurate-fiber composite parts of the present invention are of interest with outstanding mechanical properties, which can be varied within a wide range.

[0099] The inventive process allows for flawless, excellent wet-out and can be cured rapidly at 70 °C to 150 °C, preferably 70 °C to 100 °C and more particularly 75 °C to 95 °C. The resulting polyurethane-polyisocyanurate-fiber composite moldings have excellent mechanical properties and very good surfaces.

[0100] A further subject of the present invention is the polyurethane-polyisocyanurate-fiber composite part obtainable by the inventive process, and the use of the polyurethane-polyisocyanurate-fiber composite part for the production of a large number of composite materials, for example for the production of a vehicle body assembly, a door or window frame or a honeycomb reinforcement assembly, or for vacuum-assisted resin infusion, for example for the production of a structural or semi-structural assembly of a vehicle or a wind turbine.

[0101] Furthermore, the composites with polyurethane-polyisocyanurate-fiber composite parts can be used for the production - mass production of e.g. vehicle parts, train parts, air and space travel parts, ship applications, wind turbines, structural parts, adhesives, packaging, encapsulants and insulators. The polyurethane-polyisocyanurate-fiber composite parts are preferably used for the production of structural or semi-structural components for wind turbines, vehicles such as bumper, fender or roof parts and ship applications such as rotor blades, coil springs or hulls. Here, structural components are understood to be those obtained using long fibers with an average fiber length of more than 10 cm, preferably more than 50 cm, while semi-structural components are understood to be those obtained using short fibers with an average fiber length of less than 10 cm, preferably less than 5 cm.

[0102] Examples

[0103] Comparative Example 1

[0104] The polyurethane-polyisocyanurate compositions were prepared according to Table 1.

[0105]

[0106] During the laboratory evaluation of Comparative Example 1, instability of the isocyanate mixture containing an alkali metal catalyst was observed. The instability in the laboratory manifested itself in the form of solid formation within a short time (weeks to months).

[0107] Example 1: Formulation Stability

[0108] The polyurethane-polyisocyanurate compositions were prepared according to Table 2 and their properties were analyzed.

[0109]

[0110] The system of Example 1 showed very good DMA properties. The resulting composition had a Tg higher than 265 °C and maintained a high elastic modulus as the temperature was raised to 210 °C. Considering the thermodynamic properties, the results indicate a very high temperature stable system.

[0111] The stability of the isocyanate component was checked to confirm that the system provides a stable shelf life. The FTIR spectra of the isocyanate and epoxide in the isocyanate component of Example 1 were checked to understand the possible reactions that can occur between the isocyanate and epoxide mixture over time. Figure 1A and Figure 1BResults are shown for different times after mixing the isocyanate and epoxy, compared to pure isocyanate (without the epoxy). The spectra of the mixture immediately after mixing, 30 minutes after mixing, 14 days after mixing, and 50 days after mixing all closely match the spectrum of the pure isocyanate. This indicates that there is little interaction between the isocyanate and epoxy at room temperature.

[0112] The NOC content of the isocyanate blends was also evaluated over a six-month period to see if there were any changes compared to the pure isocyanate. Figure 2 The results shown show that the epoxy compound does not change the NCO content of the mixture, and it remains stable when stored for up to six months. If the NCO content of the mixture is normalized to account for the 3.5% epoxide in the mixture, the difference between the NCO content of the pure isocyanate and the mixture is eliminated. Therefore, the NCO content does not change, indicating a stable mixture.

[0113] Additionally, the gel time of the system was evaluated after aging the mixture of Parts A and B over a six month storage period. Figure 3 The results in Figure 2 show that the gelation time at 120°C ranged from 190 to 220 seconds and did not change significantly after six months, further confirming the stability of the system.

[0114] Tg is measured at temperatures between 0 and 300°C. Figure 4A and Figure 4B The results in

[15] show that even after aging for up to four months, the Tg remains above 250°C.

[0115] Example 2: Test Panels

[0116] The test panels were prepared by mixing the isocyanate component and isocyanate-reactive component mixture of Example 1 in a vacuum high-speed mixer at 800 rpm and 14 torr for 5 minutes. The component mixture was also degassed and mixed at 2000 rpm for 10 seconds before casting in a hot mold. A book-shaped mold was used in the laboratory to cast the test panels. The mold was preheated in an oven at 120°C, then removed from the oven and the component mixture was poured under a fume hood. The mold was then quickly placed in the same oven and pre-cured at 120°C for 4 minutes, after which the entire mold was moved to another oven set at 200°C and fully cured for 5 minutes. The panel was then removed from the mold and allowed to cool to room temperature for future testing.

[0117] The physical properties of the test panels of Example 1 were measured according to the following protocol:

[0118]

[0119]

[0120] Figure 5 and Figure 6 The flexural properties of test panels prepared at different times over a six-month storage period were summarized. The flexural modulus and strength at room temperature and 80°C were consistent and essentially unchanged, indicating that the chemical properties were very stable.

[0121] The foregoing description of one or more aspects is merely exemplary in nature and is in no way intended to limit the scope of the application, its application, or uses, which are instead herein described being broadest possible. The present disclosure is provided with reference to the non-limiting examples and terms included herein. These definitions and terms are not designed to function as limitations, but rather as descriptive measures and are presented herein for purposes of describing and defining the present application. Although methods or compositions are described as separate steps or using particular materials, it will be appreciated that the steps or materials can be interchangeable, such that the description of the present application can include multiple parts or steps arranged in any order, as is readily understood by those skilled in the art.

[0122] It is to be understood that, although the terms “first,” “second,” “third,” and the like can be used herein to describe various elements, components, regions, and / or steps, these elements, components, regions, layers, and / or steps should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, or segment from another element, component, region, layer, or segment. Thus, “a first element,” “component,” “region,” “layer,” or “segment” discussed above could be termed a second (or other) element, component, region, layer, or segment without departing from the teachings herein.

[0123] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms, including “at least one,” unless the content clearly indicates otherwise. “Or” means “and / or.” As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items. It will be further understood that the terms “comprises” and / or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. The term “or its combinations” means including at least one of the elements.

[0124] Certain embodiments and features have been described using a set of numerical upper limits and a set of numerical lower limits. It should be understood that ranges including any combination of any two values, e.g., between any lower limit and any upper limit value, between any two lower limit values, and / or between any two upper limit values, are contemplated unless otherwise indicated. Certain lower limits, upper limits, and ranges appear in the claims below. All numerical values are "about" or "approximately" the indicated value, and take into account experimental error and variations.

[0125] Unless defined otherwise, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that, unless otherwise defined, terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure, and are not to be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0126] In addition to those shown and described herein, various modifications will be apparent to those skilled in the art of the field to which the application pertains. Such modifications are intended to fall within the scope of the claims that follow.

[0127] The patents, publications, and applications mentioned in the specification are indicative of the levels of those skilled in the art to which the application pertains. These patents, publications, and applications are incorporated herein by reference to the same extent as if each individual patent, publication, or application was specifically and individually incorporated herein by reference.

[0128] The foregoing description is of a particular aspect of the application, which is not intended to be limiting.

Claims

1. A process for producing a molded polyurethane-polyisocyanurate-fiber composite part, the process comprising: obtaining a reaction mixture by mixing: A) an isocyanate-reactive component, the isocyanate-reactive component comprising: i. a polyol having an average functionality of 1.8 to 5.0 and a hydroxyl number of 200 to 500, and ii. an alkali metal catalyst, the alkali metal catalyst being obtainable by introducing an alkali metal salt or an alkaline earth metal salt into a compound containing a carbamate group, R-NH-CO-R', wherein R is not hydrogen and / or not COR"; B) an isocyanate component, the isocyanate component comprising: i. at least one isocyanate compound, and ii. a compound containing one or more epoxy groups; and molding the reaction mixture at a temperature between 75 °C and 220 °C under a pressure of 50 bar or more to obtain the molded polyurethane-polyisocyanurate-fiber composite part.

2. The process according to claim 1, further comprising mixing a chain extender with at least one of the isocyanate-reactive component or the isocyanate component.

3. The process according to claim 1, wherein the amount of alkali metal ions or alkaline earth metal ions per carbamate group in the alkali metal catalyst is 0.0001 to 3.5, based on the number of alkali metal or alkaline earth metal ions and carbamate groups, the fraction of the compound containing one or more epoxy groups is 0.3 to 15% by weight, based on the total weight of the compound containing one or more epoxy groups and isocyanate of the isocyanate component, and the isocyanate index is 100 to 450.

4. The process according to claim 1, wherein the isocyanate index is 100 to 450.

5. The process according to claim 1, wherein a first polyisocyanate is used as the at least one isocyanate compound and the compound containing a carbamate group in the alkali metal catalyst is a reaction product of a second polyisocyanate with a compound having OH groups.

6. The process according to claim 1, wherein the at least one isocyanate compound is a polyisocyanate prepolymer having an NCO content of 5 to 33% by weight.

7. The process according to claim 1, wherein the alkali metal and the compound having at least two OH groups, the second isocyanate are used in stoichiometric excess.

8. The process according to claim 1, wherein the amount of alkali metal ions or alkaline earth metal ions per isocyanate group in the isocyanate component and in the alkali metal catalyst is 0.0001 to 0.3, based on the number of alkali metal or alkaline earth metal ions and isocyanate groups.

9. The process according to claim 1, wherein the compound containing epoxy groups in the epoxide catalyst comprises two, three or more epoxy groups per molecule.

10. The process according to claim 1, wherein the alkali metal salt or alkaline earth metal salt in the alkali metal catalyst is lithium chloride.

11. The process according to claim 1, wherein the compound containing one or more epoxy groups is used in an amount such that the equivalent ratio of epoxy groups to isocyanate groups in the isocyanate component is from 0.1 to 2.

0.

12. The process according to claim 1, wherein the compound containing one or more epoxy groups comprises C 12 -C 14 Monofunctional glycidyl ethers of mixtures of aliphatic alcohols.

13. A polyurethane-polyisocyanurate-fiber composite part obtainable by the process according to claim 1.

14. A polyurethane-polyisocyanurate-fiber composite part obtainable by the process according to claim 1, wherein the polyurethane-polyisocyanurate-fiber composite part has a glass transition of 200 °C or higher.

15. The polyurethane-polyisocyanurate-fiber composite part according to claim 14, having a glass transition of 230 °C or higher.

16. A system for producing a molded polyurethane-polyisocyanurate-fiber composite part, the system comprising: A. an isocyanate-reactive component, the isocyanate-reactive component comprising: i. a polyol having an average functionality of 1.8 to 5.0 and a hydroxyl number of 200 to 500, and ii. an alkali metal catalyst obtainable by introducing an alkali metal salt or an alkaline earth metal salt into a compound containing a carbamate group R-NH-CO-R', wherein R is not hydrogen and / or not COR"; B an isocyanate component, the isocyanate component comprising: i. at least one isocyanate compound, and ii. a compound containing one or more epoxy groups.

17. The system according to claim 16, further comprising a chain extender with at least one of the isocyanate-reactive component or the isocyanate component.

18. The system according to claim 16, wherein the amount of alkali metal ions or alkaline earth metal ions per carbamate group in the alkali metal catalyst is from 0.0001 to 3.5, based on the number of alkali metal or alkaline earth metal ions and carbamate groups, the fraction of the compound containing one or more epoxy groups is from 0.3 wt.% to 15 wt.%, based on the total weight of the compound containing one or more epoxy groups and isocyanate of the isocyanate component, and the isocyanate index is from 100 to 450.

19. The system according to claim 16, wherein the amount of alkali metal ions or alkaline earth metal ions per isocyanate group in the isocyanate component and in the alkali metal catalyst is from 0.0001 to 0.3, based on the number of alkali metal or alkaline earth metal ions and isocyanate groups.

20. The system according to claim 16, wherein the alkali metal salt or alkaline earth metal salt in the alkali metal catalyst is lithium chloride.

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