POLYURETHANE REACTIVE SYSTEM FOR PULTRUSION

Description

[0001] The present invention relates to polyurethane reactive systems for the production of pultrudates with reinforcing fibers and their use.

[0002] Pultrusion, also known as the pultrusion process, is a continuous process for producing fiber-reinforced profiles with a constant cross-section. A pultrusion system typically consists of an impregnation unit and a heated mold, as well as a haul-off system that keeps the process running. The fibers are impregnated in an open bath or in a closed injection box. Closed injection boxes are preferred for thermosetting reactive resins, such as polyurethanes. The injection boxes can be installed as a separate unit in front of the actual mold or integrated into the mold ("direct injection"). The composite is then formed and cured in the heated mold. The finished profile is pulled from the mold using a haul-off system and then cut to the desired lengths.

[0003] To make the pultrusion process as efficient as possible, high process speeds are aimed for, along with excellent mechanical properties of the pultrudate and a high surface quality. Last but not least, low peel forces of < 3 kN reflect a fluid process. Various patents present different solutions for an effective pultrusion process with PU resins.

[0004] US2008 / 090966 A1 discloses a reaction system for producing a fiber-reinforced composite according to the pultrusion process, which is made from a continuous fiber-reinforcing material and an immiscible polyurethane formulation containing a polyisocyanate component containing at least one polyisocyanate and an isocyanate-reactive component containing at least one isocyanate-reactive compound. It is described that an improved pultrusion process can be achieved by incompatibility of the polyether polyols used within the isocyanate-reactive compound and / or incompatibility between the isocyanate-reactive compound and the isocyanate.

[0005] Typically, insoluble solids are added to the isocyanate-reactive component as additives to fulfill specific functions that cannot be equally fulfilled by single-phase isocyanate-reactive components. Consequently, these are multiphase isocyanate-reactive components. Multiphase is defined as the presence of more than one phase at room temperature within 6 months. Solids are used, for example, as water binders (e.g., WO 2011 / 067246 A1, WO2018 / 192927 A1, WO2013 / 127850 A1, US 2008 / 0090921 A1), fillers such as chalk, quartz sand, gypsum (EP3380539 A1), or encapsulated catalysts (WO 2018 / 162519 A1) to control the reaction. In addition to the liquid / solid multiphase mentioned above, a liquid / liquid multiphase also frequently occurs, similar to that observed in an oil / water mixture.In various publications, this phase instability is even described as necessary to achieve low peel forces (e.g. US 2008 / 090966 A1).

[0006] WO 2016 / 188805 discloses a process for producing polyurethane-polyisocyanurate compounds that can be used to manufacture vehicle parts or rotor blades for wind turbines. Neither a pultrusion process nor the use of a water binder B5) according to the invention nor the use of the polyols B2) or B3) according to the invention are disclosed, let alone in the quantitative ratios according to the invention.

[0007] In addition to the advantages of multi-phase systems (solid / liquid and / or liquid / liquid) already outlined, there are also the following disadvantages. For example, the logistics involved in filling and transporting a multi-phase isocyanate-reactive component poses a major challenge, as it is necessary to ensure that a homogeneous mixture is present despite the multi-phase nature. Continuous, sufficient mixing must also be ensured on the pultrusion system in order to achieve a consistent composition and consequently profile quality in the pultrusion process. Last but not least, filters are installed in the dosing unit to separate impurities from the impregnation resin, for example. These filters can become clogged by solids in the formulation and thus bring the process to a standstill. The pumps used are also sensitive to the use of solids.

[0008] The object of the present invention was therefore to develop a pultrusion process in which the disadvantages of the known processes, such as, for example, a multi-phase nature of the isocyanate-reactive component and / or only partially satisfactory mechanical properties of the resulting pultrudate, are at least partially overcome without unduly impairing the efficiency of these processes. Furthermore, the transport of the reactive system to the pultrusion plant is to be improved, and the processability of the reactive system is to be simplified, for example by exposing pumps and filters to no solids. This object was surprisingly achieved by the process according to the invention, with which the polyurethane pultrudates according to the invention were obtained using the polyurethane reactive system according to the invention, in accordance with the appended claims.

[0009] The invention relates to a polyurethane reactive system comprisingan isocyanate component A), an isocyanate-reactive component B) comprising 3 - 13 wt.% of a polyether polyol B1) having a hydroxyl number (OHN) of 20 to 50 mg KOH / g, obtainable from the reaction of a first H-functional starter compound having a functionality f of ≥2 to ≤4 with ethylene oxide and propylene oxide, 15 - 37 wt.% of a polyether polyol B2) having a hydroxyl number (OHN) of 900 - 1100 mg KOH / g, obtainable from the reaction of a second H-functional starter compound having a functionality f of ≥2 to ≤4 with a second alkylene oxide, 50 - 72 wt.% of a polyether polyol B3) having a hydroxyl number (OHN) > 50 to < 900 mg KOH / g, obtainable from the reaction of a third H-functional starter compound with a third alkylene oxide, one or several catalysts B4) and a drying agent B5) which is a trialkyl orthoformate, a p-toluenesulfonyl isocyanate, an oxazolidine or mixtures thereof, wherein the sum of the weights-% of components B1) and B2) ≤ 40 wt.%, based on the sum of the amounts of B), C) and D), and the sum of the wt.% of components B1), B2), B3), B4) and B5) ≥ 90 wt.%, based on the sum of the amounts of B), C) and D), an internal release agent C), and optionally further auxiliaries and additives D), wherein the sum of the wt.% of components B), C) and optionally D) is 100 wt.%, and wherein the hydroxyl numbers (OHN) of the polyether polyols B1), B2) and B3) were determined by means of ISO 14900. .

[0010] In one embodiment of the invention, components A), B), C) and optionally D) are used in amounts such that the ratio of the number of NCO groups in (A) to the sum of the number of isocyanate-reactive groups in (B), (C) and (D) multiplied by 100 (the so-called index or key figure) has a value of 100-150.

[0011] An isocyanate-reactive component within the meaning of this application is a component which comprises compounds which can react with the isocyanate group, e.g. hydroxyl groups (-OH), amine groups (-NH 2 or -NRH, where R is an organic radical) or thio groups (-SH).

[0012] The hydroxyl number (OHN) for the purposes of this application is the hydroxyl number, i.e., the amount of potassium hydroxide in milligrams that is equivalent to the amount of acetic acid bound during acetylation of one gram of substance. The OHN was determined for this application in accordance with ISO 14900.

[0013] The polyisocyanate component A) preferably comprises at least one of monomeric methylenedi(phenyl isocyanate) (MDI), oligomeric MDI, polymeric MDI and mixtures thereof.

[0014] The NCO content of polyisocyanate component A) is preferably above 25 wt.%, more preferably above 30 wt.%, particularly preferably above 31.5 wt.%. The functionality of polyisocyanate component A) is preferably between 2.1 and 2.9. The viscosity of polyisocyanate component A) is preferably ≤ 500 mPas (at 25 °C), measured according to DIN 53019-1.

[0015] In addition, the usual aliphatic, cycloaliphatic, araliphatic di- and / or polyisocyanates and in particular aromatic isocyanates, which are known from polyurethane chemistry, can be used. Examples of such suitable polyisocyanates are ethylene diisocyanate, 1,4-butylene diisocyanate, 1,5-pentane diisocyanate, 1,6-hexamethylene diisocyanate (HDI), 1,12-dodecane diisocyanate, cyclobutane-1,3-diisocyanate, cyclohexane-1,3- and -1,4-diisocyanate and mixtures of these isomers, isophorone diisocyanate (IPDI), 2,4- and 2,6-hexahydrotoluene diisocyanate and mixtures of these isomers, 2,2,4- and / or 2,4,4-trimethylhexamethylene diisocyanate, bis(4,4'-, 2,4'- and 2,2'-isocyanatocyclohexyl)methane or mixtures of these isomers, and aromatic isocyanates of the general formula R(NCO)z, where R is a polyvalent organic radical which has an aromatic ring, and z is an integer of at least 2 is.Examples of these are 1,3-diisocyanato-xylene, 1,3-diisocyanato-p-xylene, 1,3-diisocyanato-m-xylene, 2,4-diisocyanato-1-chlorobenzene, 2,4-diisocyanato-1-nitrobenzene, 2,5-diisocyanato-1-nitrobenzene, m-phenylene diisocyanate, p-phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, mixtures of 2,4- and 2,6-tolylene diisocyanate, 1,5-naphthalene diisocyanate, 1-methoxy-2,4-phenylene diisocyanate, 4,4'-biphenylene diisocyanate, 3,3'-dimethyl-4,4'-diphenylmethane diisocyanate, and 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate; Triisocyanates, such as 4,4',4"-triphenylmethane triisocyanate and 2,4,6-toluene triisocyanate, and tetraisocyanates, such as 4,4'-dimethyl-2,2'-5,5'-diphenylmethane tetraisocyanate and 1,3- and / or 1,4-bis-(2-isocyanato-prop-2-yl)-benzene (TMXDI), 1,3-bis-(isocyanatomethyl)benzene (XDI).

[0016] In addition to the isocyanates mentioned above, modified isocyanates, such as those with uretdione, isocyanurate, carbodiimide, uretonimine, allophanate or biuret structure, can also be used, as well as modified isocyanates in the form of prepolymers, obtainable from the reaction of one or more polyisocyanates with one or more polyols. It is possible that the isocyanate is a prepolymer which is obtainable by reacting an isocyanate with an NCO functionality of ≥ 2 and polyols with a molecular weight of ≥ 62 g / mol to ≤ 8000 g / mol and OH functionalities of ≥ 1.5 to ≤ 6.

[0017] The polyisocyanate component A) particularly preferably consists of at least one of monomeric MDI, oligomeric MDI, polymeric MDI and mixtures thereof.

[0018] The polyether polyol B1) according to the invention having a hydroxyl number (OHN) of 20 to 50 mg KOH / g is obtainable from the reaction of a first H-functional starter compound having a functionality f of ≥2 to ≤4 with ethylene oxide and propylene oxide.

[0019] The polyether polyol B1) can be one or more polyol(s).

[0020] The first H-functional starter compound is preferably one or more compound(s) selected from the group consisting of ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol, 1,4-butanediol, 1,6-hexanediol, glycerol, trimethylolpropane, pentaerythritol, ethylenediamine and triethanolamine, particularly preferably 1,2- and 1,3-propylene glycol, diethylene glycol, glycerol, trimethylolpropane and very particularly preferably glycerol and trimethylolpropane.

[0021] In one embodiment of the invention, the mass fraction of propylene oxide for the polyether polyol B1) is 60 to 90 wt.%, preferably 70 to 85 wt.%, based on the sum of ethylene oxide and propylene oxide used.

[0022] In a preferred embodiment of the invention, the polyether polyol B1) is the polyether polyol B1) obtainable by i) Reaction of the first H-functional starter compound with propylene oxide in the presence of a first catalyst to form a first intermediate ii) Reaction of the first intermediate with ethylene oxide to form a block copolymer.

[0023] In an alternative, less preferred embodiment of the invention, the polyether polyol B1) is obtainable by copolymerization of ethylene oxide and propylene oxide with the first H-functional starter compound in the presence of a first catalyst to form a copolymer.

[0024] In one embodiment of the invention, the first catalyst is potassium hydroxide, sodium hydroxide, cesium hydroxide, a double metal cyanide catalyst (DMC catalyst) and / or an amine, preferably potassium hydroxide.

[0025] The polyether polyol B2) according to the invention having a hydroxyl number (OHN) of 900 - 1100 mg KOH / g is obtainable from the reaction of a second H-functional starter compound having a functionality f of ≥2 to ≤4 with a second alkylene oxide.

[0026] The polyether polyol B2) can be one or more polyol(s).

[0027] The second H-functional starter compound is preferably one or more compound(s) selected from the group consisting of ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol, 1,4-butanediol, 1,6-hexanediol, glycerol, trimethylolpropane, pentaerythritol, ethylenediamine and triethanolamine, particularly preferably 1,2- and 1,3-propylene glycol, diethylene glycol, glycerol, trimethylolpropane and very particularly preferably glycerol and trimethylolpropane.

[0028] In one embodiment of the invention, the polyether polyol B2) is obtainable by copolymerization of the second alkylene oxide with the second H-functional starter compound in the presence of a second catalyst.

[0029] In one embodiment of the invention, the second catalyst is potassium hydroxide, sodium hydroxide, cesium hydroxide, a double metal cyanide catalyst (DMC catalyst) and / or an amine, preferably potassium hydroxide.

[0030] In one embodiment of the invention, the second alkylene oxide is propylene oxide and / or ethylene oxide, preferably propylene oxide.

[0031] The polyether polyol B3) according to the invention having a hydroxyl number (OHN) of > 50 to < 900 mg KOH / g is obtainable from the reaction of a third H-functional starter compound with propylene oxide.

[0032] The polyether polyol B3) can be one or more polyol(s).

[0033] In one embodiment, the third H-functional starter compound has a functionality f of ≥2 to ≤4.

[0034] The third H-functional starter compound is preferably one or more compound(s) selected from the group consisting of ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol, 1,4-butanediol, 1,6-hexanediol, glycerol, trimethylolpropane, pentaerythritol, ethylenediamine and triethanolamine, particularly preferably 1,2- and 1,3-propylene glycol, diethylene glycol, glycerol, trimethylolpropane and very particularly preferably 1,2-propylene glycol, glycerol and trimethylolpropane.

[0035] In one embodiment of the invention, the polyether polyol B3) is obtainable by copolymerization of the third alkylene oxide with the third H-functional starter compound in the presence of a third catalyst.

[0036] In one embodiment of the invention, the third catalyst is potassium hydroxide, sodium hydroxide, cesium hydroxide, a double metal cyanide catalyst (DMC catalyst) and / or an amine, preferably potassium hydroxide.

[0037] In one embodiment of the invention, the third alkylene oxide is propylene oxide and / or ethylene oxide, preferably propylene oxide.

[0038] In addition to the polyols B1), B2), and B3) used in the isocyanate-reactive component B), further polyether polyols, further polyester polyols, further polyether ester polyols, and / or further polycarbonate polyols can be used according to the invention. Preferably, further polyether polyols and / or further polyester polyols are used in B), particularly preferably further polyether polyols.

[0039] The other polyols used in the isocyanate-reactive component B) may contain, in addition to the OH function, other isocyanate-reactive hydrogen atoms (= active hydrogen atoms), such as NH groups and NH 2 groups. Where such other active hydrogen atoms are present, preferably more than 90%, in particular more than 95%, particularly preferably more than 99%, and most preferably 100% of all isocyanate-reactive hydrogen atoms in the isocyanate-reactive component originate from OH functions.

[0040] Such polyols are described, for example, by Ionescu in "Chemistry and Technology of Polyols for Polyurethanes", Rapra Technology Limited, Shawbury 2005, p. 31 ff. (Chapter 3: The General Characteristics of Oligo-Polyols), p. 55 ff. (Chapter 4: Oligo-Polyols for Elastic Polyurethanes), p. 263 ff. (Chapter 8: Polyester Polyols for Elastic Polyurethanes) and in particular on p. 321 ff. (Chapter 13: Polyether Polyols for Rigid Polyurethane Foams) and p. 419 ff. (Chapter 16: Polyester Polyols for Rigid Polyurethane Foams).

[0041] Preferably, polyols are used in the isocyanate-reactive component B), which can be prepared in a conventional manner by polyaddition of alkylene oxides such as propylene oxide and / or ethylene oxide to H-functional starter compounds in the presence of catalysts. The polyhydroxypolyethers are preferably prepared from an H-functional starter compound having an average of 2 to 8 active hydrogen atoms and one or more alkylene oxides, e.g. ethylene oxide, butylene oxide and / or propylene oxide. Preferred starter compounds are molecules having two to eight hydroxyl groups per molecule, such as water, ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol, 1,4-butanediol, 1,6-hexanediol, glycerol, trimethylolpropane, pentaerythritol, sorbitol and sucrose, and amine starter compounds such as ethylenediamine and triethanolamine. The starter compounds can be used alone or in a mixture.Particularly preferred are 1,2- and 1,3-propylene glycol, diethylene glycol, sorbitol, glycerol, trimethylolpropane, sucrose, and mixtures of the above-mentioned products. Representatives of the isocyanate-reactive component B) are described, for example, in the Kunststoff-Handbuch (Plastics Handbook), Volume VII "Polyurethanes," 3rd edition, Carl Hanser Verlag, Munich / Vienna, 1993, pages 57-67 and pages 88-90.

[0042] The polyester polyols are polyhydroxyl compounds containing ester groups, such as castor oil or polyhydroxypolyesters, which are obtainable by polycondensation of excess amounts of simple polyhydric alcohols of the type just mentioned as examples with preferably dibasic carboxylic acids or their anhydrides, such as adipic acid, phthalic acid or phthalic anhydride.

[0043] As catalyst B4), for example, the known polyurethane catalysts can be used, e.g. organic metal compounds, such as potassium or sodium salts of organic carboxylic acids, e.g. potassium acetate; also tin(II) salts of organic carboxylic acids, e.g. tin(II) acetate, tin(II) octoate, tin(II) ethylhexanoate and tin(II) laurate and the dialkyltin(IV) salts of organic carboxylic acids, e.g.Dibutyltin diacetate, dibutyltin dilaurate, dimethyltin dilaurate, dibutyltin maleate and dioctyltin diacetate, furthermore, for example, diisooctyl 2,2'-[(dioctylstannylene)bis(thio)]diacetate, di-n-butyl-bis(dodecylthio)tin, monooctyltin isooctylthioglycolate, isooctyl mercaptoacetate, 2-ethylhexyl 4,4'-dibutyl-10-ethyl-7-oxo-8-oxa-3,5-dithia-4-stannatetradecanoate, dimethyltin dithioglycolate and / or strongly basic amines such as 2,2,2-diazabicyclooctane, N,N-dimethylaminopropylamine, N,N-bis(3-dimethylaminopropyl)-N-isopropanolamine, triethylamine, triethylenediamine, tetramethylhexamethylenediamine, Pentamethyldiethylenetriamine, N,N-dimethylcyclohexylamine or bis(N,N-dimethylaminoethyl) ether, N,N-dimethylbenzylamine, N,N-methyldibenzylamine, and N-methylimidazole, and latent catalysts. Latent catalysts and their mechanism of action are described, for example, in EP 2531538 A1, pages 1-4 and page 9, line 26 to page 10, line 2.Typical latent catalysts are blocked amine and amidine catalysts, e.g., catalysts from Air Products (such as Polycat®< SA-1 / 10, Dabco KTM 60) and Tosoh Corporation (such as Toyocat®< DB 2, DB 30, DB 31, DB 40, DB 41, DB 42, DB 60, DB 70). Further examples of catalysts and details on their mode of action are described in the Kunststoff-Handbuch (Plastics Handbook), Volume VII "Polyurethanes," 3rd edition, Carl Hanser Verlag, Munich / Vienna, 1993, pages 104-110.

[0044] In one embodiment of the invention, the amount of catalyst B4) is 0.05 wt.% to 5 wt.%, preferably 0.05 wt.% to 2 wt.%, based on the sum of the amounts of B), C) and D).

[0045] As drying agents (B5), liquid drying agents (water binders) or dissolved drying agents (water binders) are preferably used at room temperature, i.e., 25 °C. For the purposes of this application, the terms "drying agent" and "water binder" are used synonymously.

[0046] In one embodiment of the invention, the amount of drying agent B5) is at most 5 wt.%, preferably at most 2 wt.%, in each case based on the sum of the amounts of B), C) and D.

[0047] In a preferred embodiment of the invention, the amount of drying agent B5) is 0.05 wt.% to 5 wt.%, preferably 0.05 wt.% to 2 wt.%, in each case based on the sum of the amounts of B), C) and D).

[0048] According to the present invention, the drying agent B5) is a trialkyl orthoformate, a p-toluenesulfonyl isocyanate, an oxazolidine or mixtures thereof, preferably an oxazolidine.

[0049] In a preferred embodiment, the drying agent B5) is an oxazolidine, and the oxazolidine is 3-ethyl-2-methyl-2-(3-methylbutyl)-1,3-oxazolidine and / or N-butyl-2(1-ethylpentyl)-1,3-oxazolidine, particularly preferably N-butyl-2(1-ethylpentyl)-1,3-oxazolidine.

[0050] All release agents commonly used in the production of polyurethanes can be used as internal release agents C), for example, long-chain monocarboxylic acids, in particular fatty acids such as stearic acid, amines of long-chain carboxylic acids such as stearamide, fatty acid esters, metal salts of long-chain fatty acids such as zinc stearate, or silicones. Particularly suitable are the internal release agents available specifically for pultrusion, e.g., MOLD WIZ INT-1948 MCH, MOLD WIZ INT-1947 MCH, MOLD WIZ INT-1960 MCH, available from Axel Plastics, or Luvotrent TL HB 550-D, Luvotrent TL HB 550, available from Lehmann&Voss. The internal release agents are used in amounts of 0.1-8 wt. %, preferably 0.1-6 wt. %, and particularly preferably 0.1-4 wt. %, based on the total weight of B).

[0051] As further auxiliaries and additives D), all auxiliaries and additives known for the production of polyurethanes can be used. Such substances are known and described, for example, in "Kunststoffhandbuch, Volume 7, Polyurethane," Carl Hanser Verlag, 3rd edition 1993, Chapters 3.4.4 and 3.4.6 to 3.4.11. Examples include surfactants, defoamers, emulsifiers, viscosity reducers, dyes, pigments, flame retardants, and adhesion promoters. The invention further relates to polyurethane composite materials comprising polyurethane obtainable from the polyurethane reactive system according to the invention and a fiber material.

[0052] Preferably, the fiber material is at least one of inorganic fiber material, organic fiber material, metallic fiber material, natural fiber material and combinations thereof, in particular glass fiber material and carbon fiber material or combinations thereof, particularly preferably carbon fiber material.

[0053] Another object of the invention is a process for producing the polyurethane pultrudates according to the invention comprising the steps i) Mixing components A), B), C) and optionally D) to obtain a polyurethane reactive system, ii) Conveying the polyurethane reactive system from step i) into an injection box, iii) simultaneously with process step ii) introducing fiber material through the injection box to obtain a fiber material impregnated with the polyurethane reactive system, iv) introducing the fiber material impregnated with the polyurethane reactive system into a heated curing tool, v) Curing the fiber material impregnated with the polyurethane reactive system in the curing tool to obtain a polyurethane pultrudate, vi) Pulling the polyurethane pultrudate from step v) out of the curing tool by means of a pulling mechanism, vii) Cutting the polyurethane pultrudate pulled from the curing tool to the desired length.

[0054] The mixing of components A), B), C), and optionally D) can be carried out in a manner customary for the preparation of polyurethane reactive mixtures, for example, using a high-pressure or low-pressure process. Preferably, components B), C), and optionally D) are premixed, and the resulting mixture is mixed with component A).

[0055] The temperature during impregnation of the fiber material in process step iii) is preferably 0-75 °C, particularly preferably 10-50 °C, and most preferably 15-35 °C. The curing step v) preferably takes place at a curing tool temperature of 140-220 °C, wherein the curing tool preferably has several, for example 3 or 4, zones of different temperatures.

[0056] The fiber material is in the form of continuous fibers. For the purposes of this application, continuous fibers mean fibers known to those skilled in the art, e.g., inorganic fibers, organic fibers, metallic fibers, natural fibers, preferably glass fibers, and carbon fibers, particularly preferably carbon fibers. Continuous fibers are understood to mean fiber material that is at least several meters long. These are unwound, for example, from rolls or spools. Individual fibers, so-called fiber rovings, braided fibers, fiber mats, fiber scrims, and fiber fabrics can be used as the fiber material. Particularly in fiber composites such as braided fibers, twisted fibers, or fiber fabrics, the individual fibers contained in these fiber composites can also contain shorter individual fibers. However, the fiber composite itself must be in the form of continuous material. In a preferred embodiment of the invention, the fibers are used in the form of fiber rovings.

[0057] In a further preferred embodiment of the invention, in process step iii), in addition to the fiber material, peel plies are guided through the injection box in such a way that they preferably form at least two outer sides of the finished polyurethane pultrudate. During further processing of the polyurethane pultrudates according to the invention, this peel ply can be removed to form at least two rough surfaces on the outer sides, which, for example, facilitates bonding of the polyurethane pultrudates.

[0058] The polyurethane pultrudates according to the invention can be used, for example, for the production of reinforcement profiles or structural elements in vehicle construction, aircraft construction, or wind turbines. Such lightweight reinforcement profiles can be used, for example, for the production of so-called "spar caps" in rotor blades of wind turbines.

[0059] The invention will be explained in more detail in the following examples. Examples

[0060] A pultrusion system was used with a heatable mold with internal dimensions of 60 mm x 5 mm and an injection box mounted in front of the mold. Accordingly, rectangular profiles with a width of 60 mm and a wall thickness of 5 mm were produced. Carbon fiber rovings (Pyrofil®< TRW 40 50L KNA from Mitsubishi Rayon Co. Ltd.) were used as fiber material and pulled through the injection box and the mold. The fiber concentration in the finished profile was approximately 65 vol. The polyol mixtures listed in Table 1 were each mixed with the specified amount of internal release agent and stirred thoroughly. These mixtures were each mixed using a low-pressure mixer with a static mixer at 23 °C with sufficient isocyanate to achieve the respective NCO index specified in Table 1, and the resulting polyurethane reactive system was continuously injected into the injection box.The impregnated reinforcing fibers were continuously drawn through the heated mold using the pultrusion system's haul-off mechanism and cured. The mold's temperature control was divided into three zones, with temperatures of 170 °C in Zone 1 (mold inlet in the haul-off direction), 200 °C in Zone 2 (mold center), and 220 °C in Zone 3 (mold exit). The finished profiles were then continuously cut to the desired length.

[0061] The following starting materials were used: Isocyanate component A) MDI 1: Polymeric MDI with an NCO content of 32.4 wt.%, a monomeric MDI content of 80 wt.%; the content of 2,4'-MDI and 2,2'-MDI is a total of 25 wt.% from Covestro Deutschland AG. Isocyanate-reactive component B) Polyether polyol B1) Polyol 6: Polyether polyol with an OHN = 29 mg KOH / g and a propylene oxide (PO) content of 78.1 wt.% based on the mass of PO and EO used and an ethylene oxide (EO) content of 21.9 wt.%.-% based on the mass of PO and EO used, obtainable by reacting glycerol (F=3) with propylene oxide in the presence of a KOH catalyst and subsequent reaction of the propoxylated intermediate with ethylene oxide to form a polyether polyol block copolymer Polyether polyol B2) Polyol 2: Glycerol-initiated triol, propoxylated, OHZ = 1050 mg KOH / g Polyether polyol B3) Polyol 1: Glycerol-initiated triol, propoxylated, OHZ = 235 mg KOH / g Polyol 3: Glycerol-initiated triol, propoxylated, OHZ = 400 mg KOH / g Polyol 5: Propylene glycol-initiated diol, propoxylated, OHZ = 515 mg KOH / g Other polyether polyols Polyol 4: Propylene glycol-initiated diol, propoxylated, OHZ = 28 mg KOH / g Polyol 7: Polyether monol with an OHN = 33 mg KOH / g and a propylene oxide (PO) content of 52.9 wt.% based on the mass of PO and EO used and an ethylene oxide (EO) content of 47.1 wt.-% based on the mass of PO and EO used, obtainable by reacting butyldiglycol (F=1) with propylene oxide and ethylene oxide in the presence of a KOH catalyst and subsequently reacting this intermediate with propylene oxide to form a polyether monol block copolymer. Catalysts B4) Catalyst: Diisooctyl 2,2'-[(dioctylstannylene)bis(thio)]diacetate Drying agent B5) as water binder Water binder 1: MOLSIV ®< L - powder from UOP Water binder 2: Incozol-2 (N-butyl-2(1-ethylpentyl)-1,3-oxazolidine) from Incorez Release agent C) Internal release agent (IMR): Luvotrent ®< TL HB 550 from Lehmann&Voss for pultrusion.

[0062] All quantities in Table 1 are given in parts by weight. The mechanical properties were determined using the following methods: Bending stress transverse: DIN EN ISO 14125 Bending stress axial: DIN EN ISO 178 Interlaminar shear strength (ILSS) transverse: DIN EN ISO 14130 ILSS axial: DIN EN ISO 14130

[0063] In addition, during the production of the polyurethane pultrudates, the peel force and the peel speed on the pultrusion line were determined, and the fiber impregnation, surface quality and the occurrence of abrasion were visually evaluated.

[0064] The single-phase nature of the isocyanate-reactive components used was also tested visually. For this purpose, the isocyanate-reactive components used in Examples 1-6 were stored in transparent plastic containers at room temperature for 6 months and visually inspected at regular intervals. Multiphase nature describes the occurrence of any inhomogeneity, such as phase separation, turbidity, and droplet formation. Accordingly, a single-phase isocyanate-reactive component exhibits none of these effects over a period of 6 months at room temperature. A single-phase isocyanate-reactive component is a homogeneous, clear liquid. Furthermore, a single-phase isocyanate-reactive component also exhibits none of the aforementioned effects of multiphase nature when centrifuged at 6000 rpm for 30 minutes. Table 1 Example 1 Example 2 (cf.) Example 3 (cf.) Example 4 (cf.) Example 5 (cf.) Example 6 (cf.) Polyol 1 26.47 28.47 26.47 28.47 28.47 27.90 Polyol 2 26.53 26.00 26.53 26.00 26.00 25.48 Polyol 3 29.80 23.81 29.80 23.81 23.81 23.34 Polyol 4 9.79 9.79 9.79 Polyol 5 8.90 9.26 8.897 9.26 9.26 9.08 Polyol 6 7.30 7.30 Polyol 7 11.88 Water Binder 1 2.00 Water Binder 2 0.50 0.50 0.50 Catalyst 1 0.50 0.67 0.50 0.67 0.67 1.47 IMR 4 4 4 4 4 4 Isocyanate MDI 1 MDI 1 MDI 1 MDI 1 MDI 1 MDI 1 index 115 115 115 115 115 115 Solid in the polyol No Yes No No No No Single-phase polyol Yes No Yes No No Yes Pull-off force < 3 kN Yes Yes No No No No Trigger speed 1.5 m / min 1.5 m / min max 0.9 m / min max 0.9 m / min max. 1.1 m / min max. 1.3 m / min Fiber impregnation very good very good good good very good very good surface very good very good streaky, matte streaky, matte good very good Abrasion No No Yes Yes No No Bending stress transversely >130 MPa Yes Yes No No No No Bending stress axial > 1100 MPa Yes Yes No No No Yes ILSS transverse > 14 MPa Yes Yes No No No No ILSS axial > 70 MPa Yes Yes No No No No

[0065] Example 1 corresponds to the composition according to the invention. The isocyanate-reactive component is solid-free and single-phase, resulting in good processability and good mechanical properties of the pultrudate.

[0066] Example 2 represents a known system composition based on a zeolite-based (water binder 1), i.e. a solid-containing and thus phase-unstable isocyanate-reactive component. The reactive system according to the invention has the advantage over this known composition that pumps and filters are not exposed to solids and that transport and processability are simpler and better.

[0067] Examples 3 and 4 show that systems 1 and 2 exhibit poorer processability and mechanical properties without the use of a water binder. This demonstrates that solid-free, single-phase reactive systems per se are not sufficient to combine good processability with good mechanical properties of the resulting pultrudates.

[0068] Example 5 shows that a simple replacement of water binder 1 with water binder 2, with an otherwise identical composition of the isocyanate-reactive component to Example 2, results in a solids-free system, but this does not guarantee good processability and mechanical properties of the pultrudate. Furthermore, due to the polyether composition, the system remains multiphase, with the processing disadvantages already mentioned above.

[0069] Example 6 also shows a solids-free, single-phase system. However, it is clear that only a composition of component B) according to the invention also leads to pultrudates with good mechanical properties.

Claims

1. Polyurethane reactive system comprising an isocyanate component A), an isocyanate-reactive component B) comprising 3-13% by weight of a polyether polyol B1) having a hydroxyl number (OHN) of 20 to 50 mg KOH / g obtainable by reaction of a first H-functional starter compound having a functionality f of ≥2 to ≤4 with ethylene oxide and propylene oxide, 15-37% by weight of a polyether polyol B2) having a hydroxyl number (OHN) of 900-1100 mg KOH / g obtainable by reaction of a second H-functional starter compound having a functionality f of ≥2 to ≤4 with a second alkylene oxide, 50-72% by weight of a polyether polyol B3) having a hydroxyl number (OHN) > 50 to < 900 mg KOH / g obtainable by reaction of a third H-functional starter compound with a third alkylene oxide, one or more catalysts B4) and a drying agent B5) which is a trialkyl orthoformate, a p-toluenesulfonyl isocyanate, an oxazolidine or mixtures thereof, wherein the sum of the % by weight of the components B1) and B2) is ≤ 40% by weight based on the sum of the amounts of B), C) and D) and the sum of the % by weight of the components B1), B2), B3), B4) and B5) is ≥ 90% by weight based on the sum of the amounts of B), C) and D), an internal release agent C), and optionally further auxiliary and additive substances D), wherein the % by weight of the components B), C) and optionally D) sum to 100% by weight, and wherein the hydroxyl numbers (OHN) of the polyether polyols B1), B2) and B3) were determined using ISO 14900.

2. Polyurethane reactive system according to Claim 1, wherein the components A), B), C) and optionally D) are employed in amounts such that the ratio of the number of NCO groups in (A) to the sum of the number of OH isocyanate-reactive groups in (B), (C) and (D) multiplied by 100 has a value of 100-150.

3. Polyurethane reactive system according to Claim 1 or 2, wherein the amount of drying agent B5) is not more than 5% by weight, preferably not more than 2% by weight, in each case based on the sum of the amounts of B), C) and D).

4. Polyurethane reactive system according to any of Claims 1 to 3, wherein the amount of drying agent B5) is 0.05% by weight to 5% by weight, preferably 0.05% by weight to 2% by weight, based on the sum of the amounts of B), C) and D).

5. Polyurethane reactive system according to any of Claims 1 to 4, wherein the drying agent B5) is an oxazolidine.

6. Polyurethane reactive system according to Claim 5, wherein the oxazolidine is 3-ethyl-2-methyl-2-(3-methylbutyl)-1,3-oxazolidine and / or N-butyl-2-(1-ethylpentyl)-1,3-oxazolidine, particularly preferably N-butyl-2-(1-ethylpentyl)-1,3-oxazolidine.

7. Polyurethane reactive system according to any of Claims 1 to 7, wherein for the polyether polyol B1) the mass fraction of propylene oxide is 60% to 90% by weight, preferably 70% to 85% by weight, based on the sum of ethylene oxide and propylene oxide employed.

8. Polyurethane reactive system according to any of Claims 1 to 7, wherein the polyether polyol B1) is obtainable by i) reacting the first H-functional starter compound with propylene oxide in the presence of a first catalyst to form a first intermediate ii) reacting the first intermediate with ethylene oxide.

9. Polyurethane reactive system according to Claim 8, wherein the first catalyst is potassium hydroxide, sodium hydroxide, cesium hydroxide, a double metal cyanide catalyst (DMC catalyst) and / or an amine, preferably potassium hydroxide.

10. Polyurethane reactive system according to any of Claims 1 to 9, wherein the second alkylene oxide is propylene oxide and / or ethylene oxide, preferably propylene oxide.

11. Polyurethane reactive system according to any of Claims 1 to 10, wherein the third alkylene oxide is propylene oxide and / or ethylene oxide, preferably propylene oxide.

12. Polyurethane reactive system according to any of Claims 1 to 11, wherein the amount of the catalyst B4) is 0.05% by weight to 5% by weight, preferably 0.05% by weight to 2% by weight, based on the sum of the amounts of B), C) and D).

13. Polyurethane composite material comprising polyurethane obtainable from the polyurethane reactive system according to any of Claims 1 to 12 and a fiber material.

14. Pultrusion process for producing a polyurethane composite material according to Claim 13, comprising the steps of i) mixing the components A), B), C) and optionally D) to obtain a polyurethane reactive system according to any of Claims 1 to 3, ii) conveying the polyurethane reactive system from step i) into an injection box, iii) simultaneously with process step ii) introducing fiber material through the injection box to obtain a fiber material impregnated with the polyurethane reactive system, iv) introducing the fiber material impregnated with the polyurethane reactive system into a heated curing mold, v) curing the fiber material impregnated with the polyurethane reactive system in the curing mold to obtain a polyurethane pultrudate, vi) pulling the polyurethane pultrudate from step v) out of the curing mold using a pulling mechanism, vii) cutting the polyurethane pultrudate pulled from the curing mold to the desired length.

15. Use of a polyurethane composite material according to Claim 13 for the production of reinforcing profiles or structural components or structural elements in vehicle construction, aircraft construction or of wind power plants.