Roll cover, roll shell, press shell or conveyor belt based on polyurethane containing naphthylene-1,5-diisocyanate

Abstract

The present invention relates to a component part for a machine for producing and / or treating a fibrous web, in particular for a paper machine, cardboard machine or tissue machine, wherein the component part comprises a roll shell for a roll, a roll cover for a roll, a conveyor belt or a press shell for a press roll, in particular for a press roll of a shoe press, and comprises at least one polyurethane-containing layer, wherein the polyurethane is formed by reacting a prepolymer and a cross-linking component, wherein the prepolymer is a reaction product of an isocyanate component and a polyol component, wherein i) the isocyanate component contains naphthylene-1,5-diisocyanate (NDI) in an amount of at least 50 wt.% and ii) the polyol component contains at least one polyol selected from the group consisting of polycarbonate polyols, polyether polycarbonate polyols and any mixtures thereof in an amount of at least 50 wt.%.

Description

Material handling, roller shell, press shell or conveyor belt based on polyurethane containing naphthylene-1,5-diisocyanate The present invention relates to a component for a machine for producing and / or treating a fibrous web, in particular for a paper, cardboard, or tissue machine, wherein the component is a roller shell for a roller, a roller cover for a roller, a conveyor belt, or a press shell for a press roller, in particular for a press roller of a shoe press. The present invention further relates to a method for manufacturing one of the aforementioned components. Finally, the present invention relates to a press roller, in particular a press roller of a shoe press, a conveyor belt, a roller cover for a roller, and / or a roller shell for a roller. Rollers, press rollers and conveyor belts are important components of machines for the production and / or treatment of a fibrous web, such as paper, cardboard and tissue machines. For example, rollers, and especially rollers with an elastic surface, are used in numerous process steps during papermaking. The latter are used, for instance, in sheet formation in the wire section of the paper machine, in dewatering in the press section, and in coating, drying, and smoothing in the finishing section. In such cases, the radially outermost surface of such a roller is in almost constant contact with the paper web in certain positions within the paper machine. These rollers are therefore subjected to high mechanical stresses during operation. Furthermore, they must exhibit low susceptibility to cracking, high impact resistance, good tear strength, high tear propagation resistance, high compressive strength, and sufficient hardness.At the same time, the rollers must be sufficiently abrasion-resistant and wear-resistant to ensure the longest possible service life. To give the roller surfaces the application-specific properties required for their use, rollers are typically provided with a roller covering or shell arranged on a roller core, the material of which is formulated with regard to the required application-specific properties. Press rollers, in turn, are used in a variety of presses, for example, in the form of shoe rollers in shoe presses, which are used particularly for dewatering fibrous webs such as paper webs. Such shoe presses consist of a shoe roller and a counter roller with a press gap between them. Shoe rollers comprise a stationary, i.e., non-rotating, press element, namely the shoe, and a flexible press sleeve that surrounds the shoe. The shoe is typically supported by a yoke and pressed against the surrounding press sleeve by hydraulic press elements. An oil film is usually built up between the shoe and the press sleeve for lubrication.Due to the concave design of the shoe on its side opposite the counter roller, a comparatively long press gap is created, approximately 20 times longer than that of conventional presses consisting of two rotating rollers. During operation of the shoe press, a fiber web is guided through the press gap along with one or two press felts. The liquid that escapes from the fiber web due to the pressure exerted on it within the press gap, containing dissolved and undissolved compounds such as fibers, fiber fragments, fillers, and / or additives in addition to water, is temporarily absorbed by the press felt and by recesses provided in the surface of the press shell. After exiting the press gap, the liquid absorbed by the press shell is flung off before the press shell re-enters the press gap.Furthermore, the water absorbed by the press felt is removed by suction elements after it leaves the press gap. Due to the comparatively long press gap resulting from the concave design of the shoe, such a shoe press achieves significantly better dewatering of the fiber web compared to a press consisting of two rotating rollers, thus allowing for a correspondingly shorter subsequent thermal drying process. This results in particularly gentle dewatering of the fiber web. Ideally, the press shell of such a shoe press must meet a variety of requirements to achieve optimal results. Firstly, such a press shell must be sufficiently flexible to be guided around the shoe. At the same time, the press shell must be sufficiently hard and rigid to prevent excessive deformation and deformation under the pressing load in the press gap.Furthermore, a press jacket must exhibit high wear resistance, good abrasion resistance, high resistance to crack formation, good resistance to crack propagation, and high resistance to chemicals, especially water, oil, acids, bases, and solvents. In particular, a press jacket must be characterized by very high hydrophobicity on the paper side. Conveyor belts are used particularly in paper, cardboard, and tissue machines. These belts must meet at least some of the aforementioned requirements and, in particular, must exhibit very high hydrophobicity on their paper side. For example, such conveyor belts are used in the press section of these machines to transport a fiber web through the press gap and then to a transfer point where the fiber web is handed over to the subsequent drying section. These conveyor belts typically include at least a polymer coating providing the paper side of the belt, into which a load-bearing textile structure is embedded. To meet these diverse requirements, at least in part, such components are usually made of fiber-reinforced polyurethane, i.e., a composite material in which a fiber mat or woven fabric is embedded in a polyurethane matrix.Both single-layer and multi-layer polyurethane molds are known. The polyurethane is typically formed by crosslinking a prepolymer, which is created by reacting an isocyanate component containing one or more diisocyanates with a polyol component containing one or more polyols. However, the properties of these polyurethanes often require improvement, or the polyurethanes that meet the required properties require expensive raw materials. The object of the present invention is therefore to provide a component for a machine for the production and / or treatment of a fibrous web, in particular for a paper, cardboard or tissue machine, wherein the component is a roller shell for a roller, a roller cover for a roller, a conveyor belt or a press shell for a press roller, in particular for a press roller of a shoe press, wherein the component has excellent mechanical properties and its polyurethane component can be produced from readily available and inexpensive raw materials. According to the invention, this problem is solved by a component according to claim 1. A component is provided for a machine for the production and / or treatment of a fibrous web, in particular for a paper, cardboard or tissue machine, which is a roller shell for a roller, a roller cover for a roller, a conveyor belt or a press shell for a press roller, in particular for a press roller of a shoe press, and comprises at least one polyurethane-containing layer, wherein the polyurethane is formed by reacting a prepolymer and a crosslinking component, wherein the prepolymer is a reaction product of an isocyanate component and a polyol component, wherein i) the isocyanate component is naphthylene-1,5-diisocyanate (NDI) in an amount of at least 50 wt.-% and ii) the polyol component contains at least one polyol selected from the group consisting of polycarbonate polyols, polyether polycarbonate polyols and any mixtures thereof in an amount of at least 50% by weight. This solution is based on the surprising finding that a layer of polyurethane – obtained by crosslinking a prepolymer formed from the reaction product of NDI and a polyol component based on polycarbonate polyol and / or polyether polycarbonate polyol – can not only be produced from commercially available and inexpensive raw materials, but also exhibits excellent mechanical properties and is therefore ideally suited as a material for the aforementioned component of a machine for the production and / or treatment of a fibrous web, in particular for a paper, board or tissue machine. According to the invention, the isocyanate component, from which the prepolymer has been formed by reaction with the polyol component, contains at least 50 wt% naphthylene-1,5-diisocyanate (NDI). Particularly good results are obtained when the isocyanate component contains at least 80 wt%, preferably at least 90 wt%, more preferably at least 95 wt%, and most preferably at least 99 wt% NDI, and most preferably consists entirely of NDI.Unless the isocyanate component consists entirely of NDI, it may contain other common isocyanates, such as one or more isocyanates selected from the group consisting of toluene diisocyanates (TDI) – in particular toluene-2,4-diisocyanate and toluene-2,6-diisocyanate –, methylenediphenyl isocyanates (MDI), hexamethylene diisocyanates (HDI), isophorone diisocyanates (IPDI), cyclohexane diisocyanates (CHDI), phenylene diisocyanates (PPDI), 1,3-xylylene diisocyanate (m-XDI), 1,4-xylylene diisocyanate (p-XDI), 1,4-bis(isocyanatomethyl)cyclohexane (p-HeXDI), 1,3-bis(isocyanatomethyl)cyclohexane (m-HeXDI), 3,3'-dimethyl-4,4'-biphenyl diisocyanate (TODI) and mixtures of two or more of the aforementioned compounds. However, as explained above, it is particularly preferred that the isocyanate component consists entirely or at least almost entirely of NDI. According to the present invention, the polyol component of the component containing the at least one polyurethane-containing layer comprises at least one polyol selected from the group consisting of polycarbonate polyols, polyether polycarbonate polyols, and any mixtures thereof, in an amount of at least 50% by weight. For the purposes of this invention, polyols are understood to be all alcohols having at least two hydroxyl groups and preferably a weight-averaged molecular weight of 400 to 10,000 g / mol. For the purposes of this invention, polycarbonate polyols are understood to be polyols having exclusively carbonate and hydroxyl groups, whereas polyether polycarbonate polyols have ether groups in addition to carbonate and hydroxyl groups.In addition to polycarbonate polyol and / or polyether polycarbonate polyol, the polyol component may contain one or more other polyols, such as polyether polyols, such as polytetramethylene glycol (PTMEG). Good mechanical properties are particularly achieved for the component when the polyol component consists entirely or at least predominantly of one or more polycarbonate polyols. Accordingly, it is preferred that the polyol component contains at least 70 wt.%, preferably at least 80 wt.%, more preferably at least 90 wt.%, and most preferably at least 95 wt.% of one or more polycarbonate polyols, and most preferably consists of one or more polycarbonate polyols. Preferably, the polycarbonate polyol contains only terminal hydroxyl groups and carbonate groups. The polyol component can contain one or more homopolycarbonate polyols and / or one or more copolycarbonate polyols. Homopolycarbonate polyol refers to a polycarbonate polyol consisting of only one repeating building block. a monomer is built up, whereas a copolycarbonate polyol is built up from two or more repeating building blocks or monomers. For the purposes of the present invention, an alkylene group is understood to be a CnH2n hydrocarbon group, i.e., a hydrocarbon group with two terminal radicals. Good results are obtained in particular if in the general formula (I) R 1 an alkylene group with an even number of carbon atoms, i.e., a Cx alkylene group, where x is an even integer. Particularly good results are obtained with a Ce alkylene group, a Cs alkylene group, a Cw alkylene group, and a Ci2 alkylene group. R is preferred. 1 a Ce alkylene group. In a further development of the inventive concept, it is proposed that the weight-averaged molecular weight of the at least one homopolycarbonate polyol is 400 to 10,000 g / mol, preferably 600 to 5,000 g / mol, particularly preferably 700 to 4,000 g / mol, and most preferably 1,500 to 3,000 g / mol. The molecular weight can be determined by gel permeation chromatography against a polystyrene standard. However, according to the present invention, it is preferred to determine the weight-averaged molecular weight of the structural units via the hydroxyl number, i.e., via the amount of potassium hydroxide in milligrams that is equivalent to the amount of acetic acid bound during the acetylation of 1 g of substance. The hydroxyl number can be determined by back titration according to DIN 53240 and is expressed in mg KOH / g. The weight-averaged molecular weight can then be determined, in the case of diols for example by dividing 112,200 by the hydroxyl number. According to a preferred embodiment of the present invention, the polyol component of the component containing the at least one polyurethane-containing layer comprises at least one copolycarbonate polyol. The at least one copolycarbonate polyol can be any type of copolymer, such as a statistical copolymer, an alternating copolymer, or a block copolymer. For example, the polyol component of the component containing at least one polyurethane-containing layer may contain at least one copolycarbonate polyol which contains one or more different structural units according to the following general formula (II), -OR 2 -OC(O)OR 3 -O- (II), in which all R 2 and R 3 the one or more different structural units linear Ci-C2o alkylene groups and branched Ci-C2o alkylene groups. Preferably, the average chain length of all groups is R 2 and R 3 6 carbon atoms or more. The copolycarbonate polyol can be composed of a variety of structural units according to general formula (II), wherein the individual structural units according to general formula (II) can be linked to each other via a -C(O) group and the terminal groups are linked to a H atom, for example, in the case of a composition of two structural units linked to each other via a -C(O) group according to general formula (II), a copolycarbonate polyol according to formula H-OR is formed. 2 -OC(O)OR 3 -OC(O)-OR 2 -OC(O)OR 3 to form -OH. Alternatively, the copolycarbonate polyol can contain other structural units besides one or more structural units according to the general formula (II). According to a further preferred embodiment of the present invention, the at least one copolycarbonate polyol contains one or more structural units according to the following general formula (Ha) and one or more structural units according to the following general formula (Hb) in any order: -R 2 -OC(O)O- (Ha) -R 3 -OC(O)O- (Hb), in which all R 2 and R 3 The structural units according to the general formulas (Ha) and (Hb) as defined above are therefore different from each other and are selected from linear Ci-C2o alkylene groups and branched C1-C20 alkylene groups. Preferably, the average chain length of all groups is R 2 and R 36 carbon atoms or more. The structural units according to the general formulas (Ha) and (Hb) can be statistically distributed, alternately arranged, or arranged in blocks in the copolycarbonate polyol, such that the copolycarbonate polyol is a statistical copolymer, an alternating copolymer, or a block copolymer. Good results are obtained if the polyol component of the component containing at least one polyurethane-containing layer contains at least one copolycarbonate polyol according to the general formula (III): HO-(R 4 -OC(O)O)n2-(R 5 -OC(O)O)n3-R x -OH (III), wherein R 4 and R 5 are different from each other and are independently selected from linear Ci-C2o alkylene groups and branched C1-C20 alkylene groups, R X =R 4 or R 5is and n2 and ns, independently of each other, are an integer of at least 1. Preferably the groups R 4 and R 5 in the general formula (III) are different from each other and are independently selected from linear Ce-C2o alkylene groups and branched Ce-C2o alkylene groups, preferably from linear Ce-Cu alkylene groups, further preferably from linear C6-C12 alkylene groups and particularly preferably from linear Ce-Cw alkylene groups. In a further development of the inventive concept, it is proposed that the weight-averaged molecular weight of the at least one copolycarbonate polyol is 400 to 10,000 g / mol, preferably 600 to 5,000 g / mol and particularly preferably 700 to 4,000 g / mol. According to the invention, the polyol component of the component containing the at least one polyurethane-containing layer comprises two or more different polycarbonate polyols, of which i) one is a homopolycarbonate polyol according to the general formula (I): HO-(R 1 -OC(O)O)mR 1 -OH (I), in which R 1 a linear Ce-Ci2 alkylene group, preferably a linear C6-C10 alkylene group and particularly preferably a linear Ce alkylene group is and n 1 an integer of at least 2, and of which (ii) another is a homopolycarbonate polyol different from the above according to the general formula (I), wherein R 1 a linear Ce-Cu alkylene group, preferably a linear Ce-Ci2 alkylene group and particularly preferably a linear Cα-Ci2 alkylene group is and n 1 an integer of at least 2, or is a copolycarbonate polyol. For example, the copolycarbonate polyol ii) can contain one or more different structural units according to the following general formula (II), -OR 2 -OC(O)OR 3-O- (II), in which R 2 and R 3 as defined above, i.e., all R 2 and R 3 the one or more different structural units according to general formula (II) are different from each other and are selected from linear C1-C20 alkylene groups and branched Ci-C2o alkylene groups, wherein the average chain length of all groups R 2 and R 3 preferably 6 carbon atoms or more, further preferably 6 to 10 carbon atoms, particularly preferably 7 to 9 carbon atoms and most particularly preferably 7.5 to 8.5 carbon atoms. According to a further preferred embodiment of the present invention, the copolycarbonate polyol ii) contains one or more structural units according to the following general formula (Ha) and one or more structural units according to the following general formula (Hb) in any order: -R 2 -OC(O)O- (Ila) -R 3-OC(O)O- (Hb), in which all R 2 and R 3 the structural units are defined according to the general formulas (Ha) and (Hb) as above. Preferably the aforementioned copolycarbonate polyol ii) is one according to the general formula (III): HO-(R 4 -OC(O)O)n2-(R 5 -OC(O)O)n3-R x -OH (III), in which R 4 and R 5 are different from each other and are independently selected from linear C6-C2o alkylene groups, preferably from linear Ce-Ci4 alkylene groups and particularly preferably from linear Ce-C alkylene groups, R X =R 4 or R 5 is and n2 and ns, independently of each other, are an integer of at least 1. Within the scope of the present invention, it was surprisingly found that a component containing at least one polyurethane-containing layer exhibits particularly excellent mechanical properties and, in particular, improved crack resistance, particularly low swelling, particularly good retention after hydrolysis, and an optimal tan ΔT when the polyurethane prepolymer, in addition to an isocyanate component containing at least 50 wt% NDI and preferably consisting thereof, contains a polyol component which contains a mixture of the two aforementioned polycarbonate polyols and preferably consists thereof. Preferably, the polyol component of the polyurethane of the component containing the at least one polyurethane-containing layer consists of two different polycarbonate polyols i) and ii), wherein the polyol component consists of 20 to 80 mol%, more preferably 30 to 70 mol%, particularly preferably 40 to 60 mol%, such as in particular about 50 mol%, polycarbonate polyol i) and the remainder up to 100 mol% polycarbonate polyol ii). Particularly good results are obtained if the polyol component of the polyurethane of the component containing the at least one polyurethane-containing layer consists of two different polycarbonate polyols, of which i) one is a homopolycarbonate polyol according to the general formula (I), wherein R 1 a linear Ce alkylene group and of which ii) the other is a homopolycarbonate polyol according to the general formula (I), wherein R 1a linear Cα-Ci2 alkylene group, or is a copolycarbonate polyol according to general formula (II), a copolycarbonate polyol containing in any order one or more structural units according to general formula (Ha) and one or more structural units according to general formula (Hb), or is a copolycarbonate polyol according to general formula (III), wherein R 4 and R 5 are different from each other and are independently selected from linear Ce-Cw alkylene groups. Most preferably, the isocyanate component of the polyurethane of the layer of the component containing at least one polyurethane consists of NDI and the polyol component comprises the aforementioned two or more different polycarbonate polyols or the polyol component consists of the aforementioned two or more different polycarbonate polyols. In a further development of the inventive concept, it is proposed that the prepolymer of the component layer containing at least one polyurethane has a stoichiometry of 0.85 to 1.15, where stoichiometry denotes the molar ratio of reactive hydrogen of the crosslinker to the isocyanate groups in the one or more isocyanates of the isocyanate component. With regard to the composition of the crosslinker component of the polyurethane in the component layer containing at least one polyurethane, the present patent application is not particularly limited. For example, the crosslinker component can contain at least one diol and / or one diamine. The diol is preferably an aliphatic diol or an aromatic diol, whereas aliphatic diamines, cycloaliphatic diamines, and aromatic diamines are equally suitable as diamines. Suitable examples of aliphatic diols suitable as crosslinking agents are those according to the general formula (IV): HO-(CH2)X-OH (IV), wherein x is an integer between 2 and 14. Particularly preferably, x is an integer of 2, 4, 6, 8, 10, 12 or 14 and most preferably of 2, 4 or 6. Suitable examples of diols are 1,2-ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,4-butanediol, 1,3-propanediol, 1,5-pentanediol, 1,6-hexanediol, N-N'-bis-(2-hydroxypropylaniline), hydroquinone bis-(2-hydroxyethyl ether) (HQEE), 1,3-bis(2-hydroxyethyl)resorcinol and any mixtures of two or more of the aforementioned compounds. Suitable examples of aliphatic diamines suitable as crosslinking agents are diamines selected from the group consisting of ethylenediamine (EDA), 2,2,4-trimethyl-1,6-hexanediamine, 2,4,4-trimethyl-1,6-hexanediamine, hexamethylenediamine (HMDA), 1,4-diaminocyclohexane, 1,2-diaminocyclohexane and mixtures thereof.Suitable examples of aromatic diamines suitable as crosslinking agents are bis(4-amino-2-chloro-3,5-diethylphenyl)methane (MCDEA), 4,4'-methylene-bis-2,6-diethyl-3-chloroaniline, 4,4'-methylene-bis-2-chloroaniline, 4,4'-methylene-bis-2-ethylbenzeneamine (MBOEA), 4,4'-methylene-bis-2,6-diethylaniline, 4,4'-diaminodicyclohexylmethane (PACM), 4,4'-diaminodiphenylmethane, polytetramethylene oxide di-p-aminobenzoate, polytetramethylene-3-methyl-tetramethylene ether-glycol-bis-4-aminobenzoate, trimethylene-bis-4-aminobenzoate, o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, and isophorone diamine. isobutyl-3,5-diamino-4-chlorobenzoate, 3,5-dimethylthio-2,4- or -2,6-toluenediamine (available under the trade name Ethacure 300) and 3,5-diethyltoluene-2,4-diamine as well as 3,5-diethyltoluene-2,6-diamine (available under the trade name Ethacure 100). Suitable examples of cycloaliphatic diamines suitable as crosslinkers are 4,4'-diaminodicyclohexylmethane, which is available under the trade name Amicure PACM, and 4,4'-diamino-3,3'-dimethyl-dicyclohexylmethane. In addition to aliphatic diol and / or aromatic diol and / or aliphatic diamine and / or cycloaliphatic diamine and / or aromatic diamine, or instead of aliphatic diol and / or aliphatic diamine and / or aromatic diamine, the crosslinking component may contain at least one alkanolamine, wherein the at least one alkanolamine is preferably a Ci-6-alkylmonohydroxymonoamine and particularly preferably monoethanolamine. Furthermore, the crosslinking component can contain a polyol, which can be, for example, a polyether, a polycarbonate polyol, or a polyether carbonate polyol. This polyol can also be one that is present in the prepolymer. Suitable examples of polyethers are polyethylene glycol, polypropylene glycol, polybutylene glycol, polytetrahydrofuran, polyhexamethylene glycol, polyoctamethylene glycol, and polydecamethylene glycol. Additionally, the crosslinking component can contain a triol. The crosslinking component particularly preferably contains 1,2-ethylene glycol, 1,6-hexanediol, 1,4-butanediol, hydroquinone bis-2-hydroxyethyl ether (HQEE) and / or bis(4-amino-2-chloro-3,5-diethylphenyl)methane (MCDEA). Furthermore, it is preferred, but not essential, that the crosslinking component additionally contains at least one catalyst, which is preferably a tertiary amine compound and / or an organometallic compound. Particularly good results are obtained if the at least one catalyst is a tertiary amine compound selected from the group consisting of 1,4-diazabicyclo(2,2,2)octane (DABCO), also known as triethylenediamine (TEDA), bis(2-dimethylaminoethyl) ether, alkylmorpholine, N,N-alkylbenzylamine, 1,2-dimethylimidazole, N,N-dimethylcyclohexylamine, N,N,N',N'-tetramethylethylenediamine, triethylamine, and mixtures thereof. Equally good results are obtained if at least one catalyst contains an organometallic compound with a metal selected from the group consisting of bismuth, mercury, aluminium, zirconium, iron, calcium, sodium, potassium, lead, tin, titanium, zinc, cobalt, cadmium and mixtures thereof.Particularly preferred is at least one catalyst 1,4-diazabicyclo(2.2.2)-octane (DABCO), bismuth neodecanoate, dibutyltin dilaurate, zinn octoate, dioctyltin diacetate, dibutyltin mercaptide, dibutyltin oxide, dimethyltin mercaptide, dioctyltin mercaptide or dimethyltin carboxylate. To further increase abrasion resistance, an additive such as silicone oil can be added to the polyurethane in an amount of 0.1 to 3 wt.%, and preferably 0.1 to 1.0 wt.%, based on the total weight of the polyurethane. Furthermore, it is preferred if the at least one polyurethane layer of the component comprises only one polyurethane, i.e., a polyurethane formed solely from a prepolymer by reacting the prepolymer with a crosslinking component. However, it is also possible to form the at least one polyurethane layer of the component from two or more different polyurethanes. The component according to the invention can be designed as a single layer or as multiple layers. In a multi-layered design, at least the outermost layer is at least partially composed of the polyurethane described above. In a further development of the inventive concept, it is proposed to design the component in multiple layers, wherein the outermost layer is composed of the polyurethane described above and the inner layer(s) are composed of one or more other polyurethanes, wherein the polyurethane of an inner layer forms the matrix in which a fiber mat or a fiber fabric is embedded. A further object of the present invention is a method for manufacturing the aforementioned component. Since NDI-based prepolymers are not stable in storage, but rather are unstable after their synthesis, so that the properties of the polyurethane produced therefrom deteriorate after a few hours of storage of the prepolymer, particularly with regard to hardness and modulus of elasticity, it is provided according to the invention to crosslink the polyurethane of the component's layer containing at least one polyurethane layer from freshly produced prepolymer, i.e., immediately after synthesis of the prepolymer, and to cast it into the required mold. Accordingly, the method for manufacturing the aforementioned component according to the present invention comprises the following steps: a) Melting the polyol component, b) at one or more mixing points, mixing the molten polyol component with the isocyanate component to produce the prepolymer, c) Passing the mixture obtained in step b), which reacts to form the prepolymer, through a feeder from the first mixing point to a second mixing point, d) at the second mixing point, mixing the prepolymer with the crosslinking component and e) Casting the mixture of prepolymer and crosslinking component to produce the component. Preferably, in step b) of mixing the molten polyol component with the isocyanate component, a first mass stream of the polyol component is continuously mixed with a second mass stream of the isocyanate component to form a prepolymer mass stream such that exactly the weight of prepolymer required per minute for the casting process is formed. Particularly good results are obtained if, in this process, both the first mass flow rate of the polyol component and the second mass flow rate of the isocyanate component, and thus the resulting prepolymer mass flow rate, remain essentially constant throughout the entire casting process for manufacturing the component. For example, the prepolymer mass flow rate is between 1 kg / min and 10 kg / min, more preferably between 1.5 kg / min and 5.0 kg / min, and most preferably between 2.0 kg / min and 4.5 kg / min. Particularly good results are obtained if, in the process, the feed line from the first mixing point to the second mixing point is dimensioned such that the prepolymer mass flow rate for this path takes between 5 minutes and 40 minutes, and particularly preferably between 8 minutes and 30 minutes. In a further development of the inventive concept, it is proposed that the crosslinking component be added to the prepolymer mass stream only shortly before step e) of casting. The following is particularly preferred: The crosslinking component is added to the prepolymer mass stream less than 30 seconds, most preferably less than 10 seconds and most preferably less than 2 seconds before step e). Furthermore, it is preferred that the casting step lasts at least 1 hour and is particularly preferred to last between 0.5 and 2.5 hours. the changing dome. As an alternative to casting the polyurethane as a coating, for example of a roller, in the process according to the invention the polyurethane produced according to the preceding steps a) to d) can also be cast in the form of a strand in step e), which is then cut and used as thermoplastic polyurethane (TPU) pellets. Another object of the present invention is a shoe press for dewatering a fibrous web, in particular a paper, cardboard, tissue or cellulose web, which comprises a previously described component as a press jacket. Finally, the present invention relates to a machine for producing or treating a fibrous web, in particular a paper, board or tissue machine, which comprises a previously described component, wherein the component is a conveyor belt, a roller covering of a roller and / or a roller shell of a roller. The present invention is described below by way of example only, with reference to advantageous embodiments and the accompanying drawings. This shows: Fig. 1: a schematic view of a shoe press with a press jacket according to an embodiment of the present invention and Fig. 2: a schematic view of a press section of a paper machine comprising a shoe press according to an embodiment of the present invention. Figure 1 shows a shoe press 10 comprising a shoe roller 12 and a counter roller 14. While the counter roller 14 consists of a rotating, cylindrical roller, the shoe roller 12 is composed of a shoe 16, a stationary yoke 18 supporting it, and a press shell 20. The shoe 16 is supported by the yoke 18 and pressed against the rotating press shell 20 by hydraulic pressing elements (not shown). Due to the concave shape of the shoe 16 on its side opposite the counter roller 14, a comparatively long pressing gap 22 is created. The shoe press 10 is particularly suitable for dewatering fibrous webs 24, such as paper webs. During operation of the shoe press, a fibrous web 24 with one or two press films 26, 26' is guided through the press gap 22. The liquid that escapes from the fibrous web 24 due to the pressure exerted on it in the press gap 22, containing dissolved and undissolved compounds such as fibers, fiber fragments, fillers, and / or additives in addition to water, is temporarily absorbed by the press felt(s) 26, 26' and by recesses (not shown) provided in the surface of the press jacket. After exiting the press gap 22, the liquid absorbed by the press jacket 20 is flung off before the press jacket 20 re-enters the press gap 22. In addition, the water absorbed by the press felt 26, 26' is removed by suction elements after leaving the press gap 22. Due to the comparatively long press gap 22 on the side opposite the counter roller 14, resulting from the concave design of the shoe 16, a significantly better dewatering of the fiber web 24 is achieved with such a shoe press 10 compared to a press consisting of two rotating rollers, so that the subsequent thermal drying can be correspondingly shorter. In this way, a particularly gentle dewatering of the fiber web 24 is achieved. Figure 2 shows a section of the press section of a paper machine, which includes a shoe press 10. As in the embodiment shown in Figure 1, the shoe press 10 comprises a shoe roller 12 having a press shell 20 and a press element or shoe 16, and a counter roller 14, with a press gap formed between the shoe 16 and the counter roller 14. This part of the paper machine also includes two suction rollers 28, 28' and two deflection rollers 30, 30'. During operation of the paper machine, a felt 26, guided by the suction rollers 28, 28' and which receives the fiber web 24 on the suction roller 28, is guided through the press gap. A conveyor belt, guided by the deflection rollers 30, 30', is also positioned below the felt 26, which carries the fiber web 24.The transfer belt 32 is guided through the press gap, taking the fiber web 24 from the felt 26 within the press gap and guiding it out of the press gap via the deflecting roller 30'. Due to the pressure exerted on the fiber web 24 in the press gap, liquid escapes from the fiber web. This liquid contains dissolved and undissolved compounds, such as fibers, fiber fragments, fillers, and / or additives, in addition to water. This liquid is temporarily absorbed by the felt 26 and by recesses provided in the surface of the press jacket. After exiting the press gap, the liquid absorbed by the press jacket 20 is flung off before the press jacket 20 re-enters the press gap. Furthermore, the water absorbed by the felt 26 after exiting the press gap is removed by suction elements provided on the suction roller 28'.Due to the comparatively long press gap resulting from the concave design of the shoe 16, such a shoe press achieves significantly better dewatering of the fiber web 24 compared to a press consisting of two rotating rollers, so that the subsequent thermal drying can be correspondingly shorter. In this way, a particularly gentle dewatering of the fiber web 24 is achieved. The present invention is described below by way of example with reference to advantageous embodiments and the following purely illustrative and non-limiting examples. Comparative example and examples 1 to 4 Using the method described above, three different NDI-based polyurethanes were produced and their mechanical properties were investigated. After casting, all polyurethanes were left at room temperature for 24 hours according to step e) of the method described above, before being stored or tempered at 120°C for 12 hours. After tempering, the polyurethanes were stored at room temperature for one month and then analyzed for their mechanical properties. The stoichiometry of all four polyurethanes was 1.05. The five different polyurethanes were each composed as follows: This means: Polyol “X”: A copolycarbonate polyol according to general formula (II) with an average chain length of all groups R 2 and R 3 of approximately 8 with a weight-averaged molecular weight of 2,000 g / mol, as stated in the paragraph

[0009] described in EP 3502 158 A1. Polyol UH200: ETERNACOLL UH200 manufactured by UBE Corporation, Tokyo, Japan, a homopolycarbonate polyol according to general formula (I) with R 1 = Ce alkylene group with a weight-averaged molecular weight of 2,000 g / mol. Polyol PH200: ETERNACOLL PH200 manufactured by UBE Corporation, Tokyo, Japan, a copolycarbonate polyol according to general formula(III) with R 4 = Cs alkylene group and R 5 = Ce alkylene group with a weight-averaged molecular weight of 2,000 g / mol. Polyol NL2000D: Benebiol NL2000D manufactured by Mitsubishi Chemical Corporation, Tokyo, Japan, a homopolycarbonate polyol according to general formula (I) with R 1 = Cw alkylene group with a weight-averaged molecular weight of 2,000 g / mol. 1,4-BDO: 1,4-Butanediol The following results were obtained: Crack resistance was measured by first making a cut in a sample using a standardized blade, then bending the sample with 1 million cycles, and then measuring whether and how far a crack had propagated from the cut. The tear strength was measured according to DIN 53515. Abrasion resistance was measured according to DIN 53516 and ISO 4649. Weight gain in water was measured after storage in distilled water for 4 days at 110°C. The Young's modulus, the F-10% (i.e., the force required to stretch the specimen by 10%), and the tensile strength were determined in a tensile test according to DIN 53504 / ISO 1977 before and after hydrolysis. The retention percentage is the percentage remaining after hydrolysis, i.e., after storage in distilled water for 4 days at 110°C. For example, if the Young's modulus before hydrolysis is 100 N / mm², the retention of the Young's modulus is [value missing in original text]. 2 and after hydrolysis 75 N / mm 2 The amount was 75 / 100*100%= 75%. The results show that samples NDI 2 and NDI 3, each containing a polyurethane based on NDI as an isocyanate and a polyol component (a mixture of two different polycarbonate polyols), exhibited improved properties, particularly with regard to crack resistance, weight gain, and retention after storage in distilled water for 4 days at 110°C. Reference list 10 shoe press 12 shoe roller 14 Counter roller 16 shoes 18 standing yoke 20 Pressed jacket 22 Press gap 24 Fiber web 26, 26' Pressed felt 28, 28' suction rollers 30, 30' deflection rollers 32 T ransportband / T ransferband

Claims

Patent claims 1. Component for a machine for the production and / or treatment of a fibrous web, in particular for a paper, board or tissue machine, wherein the component is a roller shell for a roller, a roller cover for a roller, a conveyor belt or a press shell for a press roller, in particular for a press roller of a shoe press, and comprises at least one polyurethane-containing layer, wherein the polyurethane is formed by reacting a prepolymer and a crosslinking component, wherein the prepolymer is a reaction product of an isocyanate component and a polyol component, wherein i) the isocyanate component contains naphthylene-1,5-diisocyanate (NDI) in an amount of at least 50 wt.% and ii) the polyol component contains at least one polyol selected from the group consisting of polycarbonate polyols, polyether polycarbonate polyols and any mixtures thereof in an amount of at least 50 wt.%. wherein the polyol component contains two or more different polycarbonate polyols, of which i) one is a homopolycarbonate polyol according to the general formula (I): HO-(R 1 -OC(O)O)mR 1 -OH (I), in which R 1 a linear Ce-Ci2 alkylene group and n 1 an integer of at least 2, and of which ii) another is a homopolycarbonate polyol different from the above according to the general formula (I), wherein R 1 a linear Ce-Cu alkylene group and n 1 is an integer of at least 2, or is a copolycarbonate polyol.

2. Component according to claim 1, characterized in that the isocyanate component contains at least 80 wt.%, preferably at least 90 wt.%, further preferably at least 95 wt.% and particularly preferably at least 99 wt.% NDI and most preferably consists of NDI.

3. Component according to claim 1 or 2, characterized in that the polyol component contains at least 70 wt.%, preferably at least 80 wt.%, further preferably at least 90 wt.% and particularly preferably at least 95 wt.% of one or more polycarbonate polyols and most preferably consists of one or more polycarbonate polyols.

4. Component according to at least one of the preceding claims, characterized in that in the general formula (I) R 1 a Ce alkylene group, a Cs alkylene group, a Cw alkylene group or a Ci2 alkylene group, and preferably a Cs alkylene group.

5. Component according to one of the preceding claims, characterized in that the weight-averaged molecular weight of the at least one homopolycarbonate polyol is 400 to 10,000 g / mol, preferably 600 to 5,000 g / mol, particularly preferably 700 to 4,000 g / mol and most preferably 1,500 to 3,000 g / mol.

6. Component according to at least one of the preceding claims, characterized in that the polyol component contains at least one copolycarbonate polyol which: i) contains one or more different structural units according to the following general formula (II), -OR 2 -OC(O)OR 3 -O- (II), in which all R 2 and R 3 the one or more different structural units according to the general formula (II) are different from each other and are selected from linear C1-C20 alkylene groups and branched Ci-C2o alkylene groups, wherein preferably the average chain length of all groups R 2 and R 3 6 carbon atoms or more, or ii) contains one or more structural units according to the following general formula (Ha) and one or more structural units according to the following general formula (Hb) in any order: -R 2-OC(O)O- (Ha) -R 3 -OC(O)O- (Hb), in which all R 2 and R 3 the structural units according to the general formulas (Ha) and (Hb) are different from each other and are selected from linear Ci-C2o alkylene groups and branched C1-C20 alkylene groups, wherein preferably the average chain length of all groups R 2 and R 3 6 carbon atoms or more, or iii) according to the general formula (III) is: HO-(R 4 -OC(O)O)n2-(R 5 -OC(O)O)n3-R x -OH (III), in which R 4 and R 5 are different from each other and are independently selected from linear Ci-C2o alkylene groups and branched Ci-C2o alkylene groups, R X =R 4 or R 5 is and n2 and ns, independently of each other, are an integer of at least 1.

7. Component according to claim 6, characterized in that in the general formula (III) R 4 and R 5 are different from each other and are independently selected from linear Ce-C2o alkylene groups and branched C6-C20 alkylene groups, preferably from linear Ce-Cu alkylene groups, more preferably from linear Ce-Ci2 alkylene groups and particularly preferably from linear Ce-Cw alkylene groups.

8. Component according to claim 6 or 7, characterized in that the weight-averaged molecular weight of the at least one copolycarbonate polyol is 400 to 10,000 g / mol, preferably 600 to 5,000 g / mol and particularly preferably 700 to 4,000 g / mol.

9. Component according to at least one of the preceding claims, characterized in that the polyol component contains two or more different polycarbonate polyols, of which i) one is a homopolycarbonate polyol according to the general formula (I): HO-(R 1-OC(O)O)mR 1 -OH (I), in which R 1 a linear Ce-Cw alkylene group and preferably a linear Ce-alkylene group is and n 1 an integer of at least 2, and of which ii) another is a homopolycarbonate polyol different from the above according to the general formula (I), wherein R 1 a linear Ce-Ci2 alkylene group and preferably a linear C7-C12 alkylene group and n 1 an integer of at least 2, preferably of 5 to 20 and particularly preferably of 5 to 16, or is a copolycarbonate polyol.

10. Component according to at least one of the preceding claims, characterized in that the other polycarbonate polyol ii) is a copolycarbonate polyol which i) contains one or more distinct structural units according to the following general formula (II), -OR 2 -OC(O)OR 3 -O- (II), in which all R 2 and R3 the one or more different structural units according to the general formula (II) are different from each other and are selected from linear C1-C20 alkylene groups and branched Ci-C2o alkylene groups, wherein preferably the average chain length of all groups R 2 and R 3 6 carbon atoms or more, preferably 6 to 10 carbon atoms, particularly preferably 7 to 9 carbon atoms and most preferably 7.5 to 8.5 carbon atoms, or ii) contains in any order one or more structural units according to the following general formula (Ha) and one or more structural units according to the following general formula (Hb): -R 2 -OC(O)O- (Ha) -R 3 -OC(O)O- (Hb), in which all R 2 and R 3the structural units according to the general formulas (Ha) and (Hb) are different from each other and are selected from linear Ci-C2o alkylene groups and branched C1-C20 alkylene groups, wherein preferably the average chain length of all groups R 2 and R 3 6 carbon atoms or more, or iii) according to the general formula (III) is: HO-(R 4 -OC(O)O)n2-(R 5 -OC(O)O)n3-R x -OH (III), in which R 4 and R 5 are different from each other and are independently selected from linear Ce-C2o alkylene groups, preferably from linear Ce-Cu alkylene groups and particularly preferably from linear Ce-Cw alkylene groups, R X =R 4 or R 5 is and n2 and ns, independently of each other, are an integer from 1 to 50, preferably from 2 to 25 and particularly preferably from 3 to 20.

11. Component according to at least one of the preceding claims, characterized in that the isocyanate component consists of NDI and the polyol component comprises or consists of two or more different polycarbonate polyols.

12. Component according to at least one of the preceding claims, characterized in that the prepolymer has a stoichiometry of 0.85 to 1.

15.

13. Component according to at least one of the preceding claims, characterized in that the crosslinking component contains 1,2-ethylene glycol, 1,6-hexanediol, 1,4-butanediol, hydroquinone bis-2-hydroxyethyl ether (HQEE) and / or bis(4-amino-2-chloro-3,5-diethylphenyl)methane (MCDEA).

14. A method for producing a component according to at least one of the preceding claims, comprising the following steps: a) melting the polyol component, b) mixing the melted polyol component with the isocyanate component at a first or more mixing points to produce the prepolymer, c) Passing the mixture obtained in step b), which reacts to form the prepolymer, through a feed line from the first mixing point to a second mixing point, d) at the second mixing point, mixing the prepolymer with the crosslinking component and e) Casting the mixture of prepolymer and crosslinking component to produce the component.

15. Shoe press for dewatering a fibrous web, in particular a paper, cardboard, tissue or cellulose web, which comprises as a press shell a component according to at least one of claims 1 to 13.

16. Machine for the production or treatment of a fibrous web, in particular a paper, cardboard or tissue machine, comprising a component according to at least one of claims 1 to 13, wherein the component is a conveyor belt, a roller covering of a roller and / or a roller shell of a roller.

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