Press sleeve or conveyor belt for a shoe press having improved properties

Abstract

The present invention relates to a press sleeve for a press roll, in particular for a press roll of a shoe press for dewatering a fibrous web, in particular a paper web, a paperboard web, a tissue web or a pulp web, or a conveyor belt, in particular a conveyor belt of a machine for producing or processing a fibrous web, in particular a paper machine, a paperboard machine or a tissue machine, wherein the press sleeve or conveyor belt comprises at least one layer comprising a polyurethane, the polyurethane being formed by reacting a prepolymer with a crosslinker component, the prepolymer being the reaction product of 1,4-phenylenediisocyanate (PPDI) and a polyol component comprising at least one polyether polyol and / or at least one polycarbonate polyol, the crosslinker component being a C 6~14 The present invention relates to a press sleeve or conveyor belt comprising a diol.

Description

[Technical field]

[0001] The present invention relates to a press sleeve or conveyor belt for a press roll, in particular for a press roll of a shoe press for dewatering a fibrous web, in particular a paper, paperboard, tissue or pulp web, in particular a conveyor belt of a machine for producing or processing a fibrous web, in particular a paper, board or tissue machine, in which the press sleeve or conveyor belt comprises at least one layer comprising polyurethane.Furthermore, the present invention relates to a method for producing said press sleeve or conveyor belt, a corresponding press sleeve and a corresponding conveyor belt.

[0002] Press rolls are used in various presses, for example in the form of shoe rolls in shoe presses, which are used in particular for the dewatering of fiber webs, such as paper webs. Shoe presses of this kind consist of a shoe roll and a counter roll, between which a press nip is formed. Here, the shoe roll consists of a fixed, i.e. non-rotating press element, i.e. a shoe, and a flexible press sleeve surrounding the shoe. The shoe is usually supported by a yoke, which supports the shoe, and is pressed by a hydraulic press element against the press sleeve surrounding the shoe. Here, an oil film is usually formed between the shoe and the press sleeve for lubrication. The shoe is designed with a concave shape on the side facing the counter roll, so that the press nip is relatively long, about 20 times longer than in a conventional press consisting of two rotating rolls.

[0003] During the operation of the shoe press, the fiber web is guided through a press nip together with one or two press felts, in which the liquid which leaves the fiber web due to the pressure acting on the fiber web in the press nip contains, in addition to water, dissolved and undissolved compounds, such as, for example, fibers, fiber fragments, fillers and / or additives, and is temporarily absorbed in the recesses provided in the press felt and press sleeve surfaces. After leaving the press nip, the liquid absorbed in the press sleeve is released from the press sleeve, which then re-enters the press nip. Also, the water absorbed in the press felt is removed by suction elements after leaving the press nip. Due to the relatively long press nip due to the concave design of the shoe, a much better dewatering of the fiber web is achieved with such a shoe press compared to a press consisting of two rotating rolls, so that the subsequent thermal drying can be correspondingly shorter. In this way, a particularly gentle dewatering of the fiber web is achieved.

[0004] Ideally, the press sleeve of such a shoe press must meet a number of requirements to obtain optimal results. On the one hand, such a press sleeve must be sufficiently flexible to allow guidance around the shoe. At the same time, the press sleeve must be sufficiently hard and rigid so as not to deform and distort excessively under the press load in the press nip. In addition, the press sleeve must have high abrasion resistance, good wear resistance, low swelling in water, as well as other properties such as high crack resistance, good crack growth resistance, and high resistance to chemicals, especially water, oil, acids, bases and solvents.

[0005] In order to at least partially meet these various requirements, such press sleeves are usually made of fiber-reinforced polyurethane, i.e. a composite material in which a fiber laid web or woven fiber is embedded in a matrix of crosslinked polyurethane, whereby both single-layer and corresponding multi-layer press sleeves are known.

[0006] WO 2015 / 086555 describes a press sleeve comprising a polyurethane obtained by reaction of a prepolymer formed from phenylene diisocyanate and polytetramethylene glycol, the reaction being carried out in the presence of a crosslinker component, which may comprise one or more of a number of different compounds.

[0007] From EP 2 284 314 A1 a press sleeve for a shoe press is known which is composed of one or more layers of crosslinked polyurethane embedded in a textile fabric. In this case the crosslinked polyurethane is the reaction product of a prepolymer made from an isocyanate component comprising 55-100 mol % of p-phenylenediisocyanate and a polyol, with a crosslinker component comprising 65-100 mol % of one or more specific polyamines. The polyol is preferably polytetramethylene glycol.

[0008] From EP 2 737 124 a press sleeve or conveyor belt for a shoe press is known, which press sleeve or conveyor belt comprises at least one layer comprising a crosslinked polyurethane which is obtainable by a process in which a prepolymer which is the reaction product of an isocyanate component comprising methylene diphenyl diisocyanate and a polyol component comprising a polycarbonate polyol is reacted with a crosslinker component which comprises at least one polyol having a weight average molecular weight of more than 1,000 g / mol.

[0009] WO 2017 / 129328 describes a press sleeve for a shoe press, the press sleeve comprising at least one layer comprising a crosslinked polyurethane, the crosslinked polyurethane being composed of a prepolymer formed from phenylene diisocyanate and a polyol, the prepolymer being crosslinked by reaction with a crosslinker component comprising 1,4-butanediol or 1,4-hydroquinone bis(2-hydroxyethyl) ether, and further aliphatic diamines and alkanolamines.

[0010] Although the press sleeve known from the last-mentioned publication has a relatively high resistance to water and chemicals, its mechanical properties leave room for improvement, in particular its hardness, elastic modulus, abrasion resistance, wear resistance and swelling in water.

[0011] It is therefore an object of the present invention to provide a press sleeve or conveyor belt which has improved mechanical properties, in particular improved hardness, improved elastic modulus, improved abrasion resistance, improved wear resistance and improved swelling in water.

[0012] According to the invention, the object is to provide a press sleeve for a press roll, in particular for a press roll of a shoe press for dewatering a fibrous web, in particular a paper, paperboard, tissue or pulp web, or a conveyor belt, in particular a machine for producing or processing a fibrous web, in particular a conveyor belt of a paper, board or tissue machine, in which the press sleeve or conveyor belt comprises at least one layer comprising a polyurethane, the polyurethane being formed by reacting a prepolymer with a crosslinker component, the prepolymer being the reaction product of 1,4-phenylenediisocyanate (PPDI) with a polyol component comprising at least one polyether polyol and / or at least one polycarbonate polyol, the crosslinker component being a C 6~14 The solution is provided by providing a press sleeve or conveyor belt comprising a diol.

[0013] Surprisingly, within the scope of the present invention, a prepolymer formed from the reaction product of PPDI with a polyol component comprising at least one polyether polyol and / or at least one polycarbonate polyol is preferably prepared by the addition of at least one relatively long-chain diol, i.e., C 6~14It has been found that layers of polyurethane obtained by crosslinking with a crosslinker component comprising a diol, for example 1,6-hexanediol in particular, have improved hardness, improved elastic modulus, improved abrasion resistance, improved wear resistance, and improved (i.e. lower) swelling in water and hydrogen peroxide, compared to corresponding layers of conventional polyurethanes crosslinked with 1,4-butanediol. It was also surprising that such polyurethane layers are nevertheless characterized by other desired properties such as good crack resistance, good crack growth resistance, and high resistance to chemicals, in particular water, oil, acids, bases and solvents. Indeed, in addition to 1,4-butanediol and other crosslinkers, hexanediol, heptanediol, octanediol, etc. are sometimes catalogued in publications as possible crosslinkers for polyurethanes based on, for example, 4,4'-methylenediphenylisocyanate (MDI), but without any indication of their advantageous properties compared to 1,4-butanediol, much less the aforementioned advantageous properties compared to 1,4-butanediol. Those skilled in the art will recognize that long-chain crosslinkers, i.e., C 2H 3H 4H 5H 6H 8H 9H 10H , in particular 1,6-hexanediol, are not particularly suitable for use as crosslinkers. 6~14 The aforementioned advantages are particularly surprising since one would expect that the diol would have poorer separation of the hard and soft segments compared to 1,4-butanediol, and therefore a lower density of the hard segments, resulting in lower hardness, higher swelling in water, and poorer abrasion resistance of the polyurethanes made therefrom. Without wishing to be bound by any theory, it is believed that the aforementioned advantageous properties are due to the longer chain C diols than 1,4-butanediol. 6~14 This is believed to be due to the fact that the proportion of hard segments in the polyurethane increases due to the diol.

[0014] According to the present invention, the crosslinker component of the polyurethane of the press sleeve or conveyor belt is C 6~14 Regardless of the positions of the two hydroxyl groups in the diol, C 6~14 Contains diol. Therefore, C 6~14The diol can be a corresponding diol having only terminal hydroxyl groups, a corresponding diol having only internal hydroxyl groups, or a corresponding diol having one terminal hydroxyl group and one internal hydroxyl group.

[0015] However, in particular, it is preferred that the crosslinker component of the polyurethane is a corresponding diol having only terminal hydroxyl groups, i.e. HO-(CH2) x -OH (I) Good results are obtained when the diol comprises a diol according to the formula: where x is an integer from 6 to 14. Advantageously, x is an integer from 6 to 12, particularly preferably an integer from 6 to 10 and very particularly preferably an integer from 6 to 8.

[0016] Preferably, x in general formula (I) is an integer multiple of 2, i.e., 6, 8, 10, 12 or 14. Most preferably, x in general formula (I) is 6, i.e., the diol is 1,6-hexanediol.

[0017] In order to obtain the above-mentioned effects of the present invention at a particularly high level, the crosslinking agent component is preferably 2 to 15% by weight, more preferably 3 to 11% by weight, further preferably 4 to 10% by weight, and particularly preferably 5 to 7% by weight of C based on the total weight of the polyurethane. 6~14 It is proposed in a development of the inventive concept to include a diol, preferably a diol according to the general formula (I). In particular, it is preferred that the crosslinker component comprises 2 to 15% by weight, preferably 3 to 11% by weight, further preferably 4 to 10% by weight, particularly preferably 5 to 7% by weight, of 1,6-hexanediol, based on the total weight of the polyurethane.

[0018] The stoichiometry H / NCO, ie the molar ratio between crosslinker component and prepolymer, is advantageously between 1.15 and 0.85, particularly preferably between 1.1 and 1.0.

[0019] In order to adjust the viscosity of the newly crosslinked polyurethane to a viscosity suitable for the manufacture of press sleeves or conveyor belts, in particular a viscosity sufficiently high for processability for forming press sleeves or conveyor belts, the crosslinker component is 6~14 It is proposed in a development of the inventive concept to include at least one alkanolamine in addition to the diol.

[0020] In particular, at least one alkanolamine is 1~6 Good results are obtained with alkyl monohydroxy monoamines.

[0021] Advantageously, the at least one alkanolamine has the general formula (II): HO-(CH2) n1 -NH2(II) wherein n1 is an integer from 1 to 6, preferably from 1 to 4.

[0022] Most preferably, the at least one alkanolamine is monoethanolamine.

[0023] According to a further preferred embodiment of the present invention, the crosslinker component contains 0.01 to 2 wt %, more preferably 0.05 to 1 wt %, and particularly preferably 0.1 to 0.5 wt % of alkanolamine, based on the total weight of the polyurethane.

[0024] Advantageously, the crosslinker component comprises from 0.01 to 15 mol %, preferably from 5 to 10 mol %, of alkanolamine relative to the total weight of the crosslinker component.

[0025] In order to adjust the viscosity of the freshly crosslinked polyurethane to a viscosity suitable for the manufacture of press sleeves or conveyor belts, in particular a viscosity sufficiently high for processability for forming press sleeves or conveyor belts, it is also possible to add at least one aliphatic diamine to the crosslinker component instead of the aforementioned alkanolamines. It is also possible for the crosslinker component to contain both at least one alkanolamine and at least one aliphatic diamine in order to adjust the desired viscosity.

[0026] Examples of suitable aliphatic diamines are those selected from the group consisting of ethylenediamine (EDA), 2,2,4-trimethyl-1,6-hexanediamine, 2,4,4-trimethyl-1,6-hexanediamine, hexamethylenediamine (HMDA), and mixtures thereof.

[0027] In particular, good results are obtained when the at least one aliphatic diamine is hexamethylenediamine (HMDA).

[0028] According to a further preferred embodiment of the present invention, the crosslinker component contains 0.01 to 2% by weight, preferably 0.05 to 1% by weight, particularly preferably 0.1 to 0.5% by weight of an aliphatic diamine, based on the total weight of the polyurethane.

[0029] Advantageously, the crosslinker component comprises 0.1 to 10 mol %, preferably 2 to 8 mol %, of an aliphatic diamine relative to the total weight of the crosslinker component.

[0030] In a further development of the inventive concept, the crosslinker component is 6~14 It is proposed to include at least one catalyst in addition to the diol. The addition of at least one catalyst is preferred in order to achieve sufficiently rapid crosslinking of the polyurethane, so that the polyurethane does not remain liquid for too long during processing and does not cause corrugations on the surface of the press sleeve or conveyor belt. The addition of a catalyst to the crosslinker component is preferred in order to achieve a crosslinking of the polyurethane sufficiently quickly, so that the polyurethane does not remain liquid for too long during processing and does not cause corrugations on the surface of the press sleeve or conveyor belt. 6~14It is preferred whether or not the composition contains at least one alkanolamine and / or at least one aliphatic diamine in addition to the diol.

[0031] Advantageously, the catalyst is at least one tertiary amine compound and / or at least one organometallic compound.

[0032] In particular, good results are obtained when 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 called triethylenediamine (TEDA), triethylamine, and mixtures thereof. Similarly good results are obtained when the at least one catalyst comprises an organometallic compound having a metal selected from the group consisting of bismuth, mercury, aluminum, zirconium, iron, calcium, sodium, potassium, lead, tin, titanium, and mixtures thereof.

[0033] Particularly preferably, the at least one catalyst is 1,4-diazabicyclo(2.2.2)octane (DABCO) and / or bismuth neodecanoate.

[0034] According to a further preferred embodiment of the present invention, the crosslinker component contains 0.01 to 1 wt %, preferably 0.02 to 0.5 wt %, particularly preferably 0.05 to 0.2 wt %, of a tertiary amine compound and / or an organometallic compound, based on the total weight of the polyurethane.

[0035] Advantageously, the crosslinker component comprises 0.01 to 5 mol %, preferably 1 to 3 mol %, of a tertiary amine compound relative to the total weight of the crosslinker component.

[0036] In a development of the inventive concept, the crosslinker component is 6~14 In addition to the diol, it is proposed to include at least one polyether polyol and / or polycarbonate polyol. This addition is necessary because the crosslinker component contains at least one C 6~14It is preferred whether or not, in addition to the diol, it contains at least one alkanolamine and / or at least one aliphatic diamine and / or at least one catalyst. By adding polyether polyols or polycarbonate polyols, the hardness of the polyurethane can be fine-tuned.

[0037] Suitable examples of polyether polyols are those selected from the group consisting of polytetramethylene ether glycol (PTMEG), polypropylene glycol (PPG), polyethylene glycol (PEG), polyhexamethylene ether glycol and mixtures. Polytetramethylene ether glycol (PTMEG) is particularly preferred.

[0038] In particular, the crosslinker component has the general formula (III): -(OR 1 -OC(O) n2 -O- (III) Good results are obtained when the composition contains at least one polycarbonate polyol having the formula R 1 is a linear C1-C 20 Alkylene groups and branched C1-C 20 alkylene groups, n2 is an integer from 3 to 30.

[0039] According to an alternative embodiment, the polycarbonate polyol may also have different alkylene groups, for example in particular 2, 3 or 4 different alkylene groups. For example, the polycarbonate polyol may have a first C1-C 20 An alkylene group A, for example a linear C3 alkylene group, and a second C1-C 20 and an alkylene group B, for example a linear C6 alkylene group, in which case the two groups can be arranged alternatingly, in blocks or randomly, for example ABAB, AAAB, AABB, BBAA or BAAA.

[0040] According to a further preferred embodiment of the present invention, the crosslinker component comprises 0.1 to 15% by weight, preferably 0.5 to 10% by weight, particularly preferably 1 to 5% by weight, of polyether polyol and / or polycarbonate polyol, based on the total weight of the polyurethane.

[0041] Advantageously, the crosslinker component comprises 0.1 to 15 mol %, preferably 0.5 to 10 mol %, of polyether polyol and / or polycarbonate polyol relative to the total weight of the crosslinker component.

[0042] In a further development of the inventive concept, the crosslinker component is - 2 to 15% by weight C 6~14 Diol, - 0.01 to 2% by weight of alkanolamines, - 0.01 to 2% by weight of an aliphatic diamine, - 0.001 to 1% by weight of a tertiary amine compound and / or an organometallic compound, and - 0.1 to 15% by weight of polyether polyols and / or polycarbonate polyols It is proposed to include:

[0043] In particular, the crosslinking agent component is - 2 to 15% by weight of 1,6-hexanediol, - 0.01 to 2% by weight C 1~6 Alkyl monohydroxy monoamines, - 0.01 to 2% by weight of an aliphatic diamine selected from the group consisting of ethylenediamine, 2,2,4-trimethyl-1,6-hexanediamine, 2,4,4-trimethyl-1,6-hexanediamine and hexamethylenediamine, - 0.001 to 1% by weight of 1,4-diazabicyclo(2.2.2)octane (DABCO) and / or organometallic compounds, and - 0.1 to 15% by weight of polyether polyol Good results are obtained when the

[0044] Particularly preferably, the crosslinker component is - 2 to 15% by weight of 1,6-hexanediol, - 0.01 to 2% by weight of monoethanolamine, 0.01 to 2% by weight of hexamethylenediamine, - 0.001 to 1% by weight of 1,4-diazabicyclo(2.2.2)octane (DABCO) and / or organometallic compounds, and - 0.1 to 15% by weight of polytetramethylene ether glycol Includes.

[0045] According to a further particularly preferred embodiment of the present invention, the crosslinker component of the polyurethane of the press sleeve or conveyor belt does not contain any aliphatic triol compounds, preferably does not contain any triol compounds such as trimethylenepropane (TMP). The addition of triol compounds leads to a decrease in the modulus of the polyurethane, a decrease in crack resistance, a decrease in tear propagation resistance and a lack of abrasion resistance, possibly because these compounds interfere with the formation of hard segments in the polyurethane.

[0046] According to the invention, the polyol component of the prepolymer comprises at least one polyether polyol and / or at least one polycarbonate polyol. In principle, the polyether polyol of the polyol component, as well as any polyether polyol of the crosslinker component, can be selected from the group consisting of polytetramethylene ether glycol (PTMEG), polypropylene glycol (PPG), polyethylene glycol (PEG), polyhexamethylene ether glycol and mixtures.

[0047] According to a further very particularly preferred embodiment of the present invention, the polyol component comprises polytetramethylene glycol (PTMEG) as at least one polyether polyol or the polyol component consists entirely of PTMEG. 6~14The particular combination with the diol provides a particularly good improvement and balance of hardness, modulus, abrasion resistance, wear resistance and swell properties of the polyurethane of the press sleeve or conveyor belt.

[0048] In particular, good results are obtained when the PTMEG has a weight-average molecular weight of 100 to 10,000 g / mol, preferably 500 to 5,000 g / mol, particularly preferably 1,000 to 3,000 g / mol, most preferably 1,000 to 2,500 g / mol. The molecular weight can be determined by gel permeation chromatography against polystyrene standards. However, according to the invention, it is preferred to determine the weight-average molecular weight of the structural units by the hydroxyl number, i.e. the amount of potassium hydroxide in milligrams that corresponds 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 given in mg KOH / g. The weight-average molecular weight can be calculated by dividing 112,200 by the hydroxyl number.

[0049] Good results are also obtained when the polyol component comprises a mixture of a polyether polyol, preferably polytetramethylene glycol, and a polycarbonate polyol, and particularly preferred is a mixture of a polyether polyol, preferably polytetramethylene glycol, and a polycarbonate polyol.

[0050] Advantageously, the polycarbonate polyol of the polyol component, whether it is used alone or in admixture with a polyether polyol, has the general formula (IV): -(OR 2 -OC(O) n3 -O- (IV) where: R 2 is a linear C1-C 20 Alkylene groups and branched C1-C 20 alkylene groups, n3 is an integer of at least 3.

[0051] According to an alternative embodiment, the polycarbonate polyol may also have different alkylene groups, for example in particular 2, 3 or 4 different alkylene groups. For example, the polycarbonate polyol may have a first C1-C 20 An alkylene group A, for example a linear C3 alkylene group, and a second C1-C 20 and an alkylene group B, for example a linear C6 alkylene group, in which case the two groups can be arranged alternatingly, in blocks or randomly, for example ABAB, AAAB, AABB, BBAA or BAAA.

[0052] Advantageously, the H / NCO ratio of the polyurethane is between 1.1 and 1.0.

[0053] To further enhance the abrasion resistance, silicone oil as an additive may be added to the polyurethane in an amount of 0.1 to 3% by weight, preferably 0.5 to 1.5% by weight, based on the total weight of the polyurethane.

[0054] For the reasons stated above, it is preferred that not only the crosslinker component but also the polyurethane itself does not contain an aliphatic triol compound, and preferably does not contain a triol compound.

[0055] Furthermore, it is preferred that the polyurethane layer of the press sleeve or conveyor belt, and all polyurethane layers if more than one polyurethane layer is present, comprise only one type of polyurethane, i.e., polyurethane formed from a prepolymer by reaction of said prepolymer with a crosslinker component.

[0056] The press sleeve according to the invention or the conveyor belt according to the invention can be designed in a single layer or in a double layer, in which case at least the outer layer is made of the abovementioned polyurethane.

[0057] In a development of the concept of the invention, it is proposed that the press sleeve or conveyor belt is made of two layers, with an outer layer made of the aforementioned polyurethane and an inner layer made of another polyurethane, the polyurethane of the inner layer forming a matrix in which the fiber laid web or fiber woven fabric is embedded.

[0058] A further subject of the invention is a shoe press for dewatering a fibrous web, in particular a paper, paperboard, tissue or pulp web, which is provided with a press sleeve as described above.

[0059] Furthermore, the invention relates to a machine for producing or processing a fibrous web, in particular a paper, board or tissue machine, which is equipped with a conveyor belt as described above.

[0060] Finally, the present invention provides a method for producing the press sleeve or conveyor belt described above, comprising the steps of: a) providing at least one rotatably mounted winding mandrel; b) providing a crosslinker component as described above; c) providing a prepolymer as a reaction product of PPDI and the aforementioned polyol component; d) mixing the prepolymer with a crosslinker component to produce a polyurethane; e) spreading the prepolymer and crosslinker mixture onto a surface of a take-up mandrel to form at least one polymer layer of a press sleeve or conveyor belt; f) curing the at least one polymer layer; g) removing the press sleeve or conveyor belt thus produced from the winding mandrel; The present invention relates to a method comprising the steps of:

[0061] The invention will now be described, purely by way of example, with reference to preferred embodiments and with reference to the accompanying drawings, in which: [Brief description of the drawings]

[0062] [Figure 1] 1 is a schematic diagram of a shoe press equipped with a press sleeve according to an embodiment of the present invention; [Diagram 2] 1 is a schematic diagram of a press section of a papermaking machine including a shoe press and conveyor belt according to an example embodiment of the present invention.

[0063] 1 shows a shoe press 10, which comprises a shoe roll 12 and a counter roll 14. Whereas the counter roll 14 consists of a rotating cylindrical roll, the shoe roll 12 consists of a shoe 16, a stationary yoke 18 supporting the shoe 16, and a press sleeve 20. Here, the shoe 16 is supported by the yoke 18 and pressed against the press sleeve 20 surrounding the shoe 16 by a hydraulic press element (not shown). The shoe 16 is designed concave on the side facing the counter roll 14, so that the press nip 22 is relatively long.

[0064] The shoe press 10 is particularly suitable for dewatering a fibrous web 24, such as a paper web. During operation of the shoe press, the fibrous web 24 is guided through the press nip 22 together with one or two press felts 26, 26', in which liquid leaving the fibrous web 24 due to the pressure acting on the fibrous web 24 in the press nip 22, which liquid contains, in addition to water, dissolved and undissolved compounds, such as, for example, fibers, fiber fragments, fillers and / or additives, and which is temporarily absorbed in the press felts 26, 26' and in recesses (not shown) provided in the press sleeve surface. After leaving the press nip 22, the liquid absorbed in the press sleeve 20 is released from the press sleeve 20, which then re-enters the press nip 22. Also, the water absorbed in the press felts 26, 26' is removed by suction elements after leaving the press nip 22.

[0065] Due to the relatively long press nip 22 due to the concave design of the shoe 16 on the side facing the counter roll 14, a significantly better dewatering of the fibrous web 24 is achieved with such a shoe press 10 compared to a press consisting of two rotating rolls, so that the subsequent thermal drying can be correspondingly shorter. In this way, a particularly gentle dewatering of the fibrous web 24 is achieved.

[0066] In FIG. 2 a cross section of the press section of a papermaking machine with a shoe press 10 is shown. Here, similar to the embodiment shown in FIG. 1, the shoe press 10 comprises a shoe roll 12 with a press sleeve 20 and a press element or shoe 16, and a counter roll 14, between which a press nip is formed. Furthermore, this part of the papermaking machine comprises two suction rolls 28, 28' and two deflection rolls 30, 30'. During operation of the papermaking machine, a felt 26 guided by the suction rolls 28, 28' picks up the fiber web 24 at the suction roll 28 and is guided through the press nip. Furthermore, below the felt 26 guiding the fiber web 24, a conveyor or transport belt 32 guided by the deflection rolls 30, 30' is guided through the press nip, whereby the transport belt 32 takes over the fiber web 24 from the felt 26 in the press nip and removes it from the press nip by the deflection roll 30'. The pressure acting on the fibrous web 24 in the press nip expels liquid from the fibrous web, which in addition to water also contains dissolved and undissolved compounds, such as, for example, fibers, fiber fragments, fillers and / or additives, and which is temporarily absorbed in the recesses provided in the felt 26 and in the press sleeve surface. After leaving the press nip, the liquid absorbed in the press sleeve 20 is released from the press sleeve 20, which then re-enters the press nip. Also, the water absorbed in the felt 26 is removed by the suction elements provided in the suction roll 28' after leaving the press nip. Due to the relatively long press nip due to the concave design of the shoe 16, a significantly better dewatering of the fibrous web 24 is achieved with such a shoe press compared to a press consisting of two rotating rolls, so that the subsequent thermal drying can be correspondingly shorter. In this way, a particularly gentle dewatering of the fibrous web 24 is achieved.

[0067] The invention will now be described, purely by way of example, on the basis of advantageous embodiments and with reference to the following non-limiting, purely illustrative examples.

[0068] Example 1 As prepolymer, the commercial product LFP E560 from Lanxess AG (Cologne, Germany), which is a prepolymer of PPDI and PTMEG with an NCO content of 5.6%, was used.

[0069] Additionally, a crosslinker component was prepared with the following composition: 84.9 mol % 1,6-hexanediol (corresponding to 72.3 wt % of the crosslinker component); 1.3 mol % PTMEG, 2000 g / mol (corresponding to 19.4 wt % of the crosslinker component); 1.6 mol % DABCO (corresponding to 1.3 wt % of the crosslinker component); 8.0 mol % monoethanolamine (corresponding to 3.5 wt % of the crosslinker component); 4.2 mol % hexamethylenediamine (corresponding to 3.5 wt % of the crosslinker component).

[0070] As is known and described, for example, in DE 102017115084 A1, the press sleeve was produced by means of a rotatable winding mandrel, in which the prepolymer and the crosslinker component were fed separately from one another to a casting device with a mixing chamber and a casting nozzle downstream thereof, the prepolymer and the crosslinker component were continuously mixed with one another in the mixing chamber, and the mixture thus produced was then continuously applied to the rotating winding mandrel by means of the casting nozzle. Here, the prepolymer and the crosslinker component were mixed with one another in a ratio of 9.89 g of crosslinker component per 100 g of prepolymer.

[0071] Furthermore, to determine the polyurethane properties, polyurethane sheets were produced by mixing the prepolymer and crosslinker components with one another and then casting the mixture thus produced into sheets: Shore A hardness (measured according to DIN 53505-A), Shore A hardness after hydrolysis, abrasion value in mm (measured according to DIN 53516), abrasion value after hydrolysis in mm, weight gain in water in %, weight gain in hydrogen peroxide, N / mm 2Elastic modulus (E-Modul) in units (measured according to DIN 53504) and N / mm 2 The F(10%) in units (measured according to DIN 53504) was determined. The results are summarized in the table below.

[0072] Comparative Example 1 The same procedure was followed as in Example 1, except that the following crosslinker components were used: 84.9 mole % 1,2-ethylene glycol, 1.3 mol% PTMEG, 2000 g / mol; 1.6 mol% DABCO, 8.0 mol % monoethanolamine, 4.2 mole % hexamethylenediamine.

[0073] The measurement results are summarized in the table below.

[0074] Comparative Example 2 The same procedure was followed as in Example 1, except that the following crosslinker components were used: 84.9 mol% 1,4-butanediol, 1.3 mol% PTMEG, 2000 g / mol; 1.6 mol% DABCO, 8.0 mol % monoethanolamine, 4.2 mole % hexamethylenediamine.

[0075] The measurement results are summarized in the table below.

[0076] [Table 1]

[0077] [Table 2] [Explanation of symbols]

[0078] 10 Shoe Press 12 Shoe Roll 14 Counter Roll 16 Shoe 18 Stationary Yoke 20 Press Sleeve 22 Press nip 24 Fiber Web 26,26' Press Felt 28,28' Suction Roll 30,30' deflection roll 32 Conveyor belt / transport belt

Claims

1. A press sleeve for a press roll, particularly for dewatering a fibrous web, in particular a paper web, a cardboard web, a tissue web or a pulp web, or a conveyor belt, particularly a conveyor belt of a machine for manufacturing or processing a fibrous web, particularly a paper machine, a cardboard machine or a tissue machine, wherein the press sleeve or the conveyor belt comprises at least one layer containing polyurethane, and the polyurethane is formed by reacting a prepolymer with a crosslinking agent component, the prepolymer being a reaction product of 1,4-phenylene diisocyanate (PPDI) and a polyol component containing at least one polyether polyol and / or at least one polycarbonate polyol, and the crosslinking agent component is C ６～１４ A press sleeve or a conveyor belt containing a diol.

2. The press sleeve or conveyor belt according to claim 1, wherein the crosslinking agent component contains a diol of formula (I) HO-(CH ２ ) ｘ -OH (I) wherein X is an integer from 6 to 14, preferably 6, 8, 10, 12 or 14.

3. The press sleeve or conveyor belt according to claim 2, wherein the crosslinking agent component contains 1,6-hexanediol.

4. The press sleeve or conveyor belt according to claim 1, wherein the crosslinking agent component contains 2 to 15% by weight of C ６～１４ diol, preferably the diol according to the general formula (I), particularly preferably 1,6-hexanediol, based on the total weight of the polyurethane.

5. The press sleeve or conveyor belt according to claim 1, wherein the crosslinking agent component further contains at least one alkanolamine, and the at least one alkanolamine is preferably C １～６The press sleeve or conveyor belt according to claim 1, which is an alkyl monohydroxy monoamine, particularly preferably monoethanolamine.

6. The crosslinking agent component further comprises at least one aliphatic diamine, and the aliphatic diamine is preferably selected from the group consisting of ethylenediamine (EDA), 2,2,4-trimethyl-1,6-hexanediamine, 2,4,4-trimethyl-1,6-hexanediamine, hexamethylenediamine (HMDA) and mixtures thereof, particularly preferably hexamethylenediamine (HMDA). The press sleeve or conveyor belt according to claim 1.

7. The crosslinking agent component further comprises at least one catalyst, and the catalyst is preferably a tertiary amine compound and / or an organometallic compound. The press sleeve or conveyor belt according to claim 1.

8. The crosslinking agent component further comprises at least one polyether polyol and / or polycarbonate polyol. The press sleeve or conveyor belt according to claim 1.

9. The crosslinking agent component does not contain an aliphatic triol compound, preferably does not contain a triol compound. The press sleeve or conveyor belt according to claim 1.

10. The polyol component contains polytetramethylene glycol as a polyether polyol. The press sleeve or conveyor belt according to claim 1.

11. The polytetramethylene glycol has a weight average molecular weight of 100 to 10,000 g / mol, preferably 500 to 5,000 g / mol, particularly preferably 1,000 to 3,000 g / mol, and most preferably 1,000 to 2,500 g / mol. The press sleeve or conveyor belt according to claim 10.

12. The crosslinking agent component is based on the total weight of the polyurethane - 2 to 15% by weight of C ６～１４ diol, - 0.01 to 2% by weight of an alkanolamine, - 0.01 to 2% by weight of an aliphatic diamine, - 0.001 to 1% by weight of a tertiary amine compound and / or an organometallic compound, and - 0.1 to 15% by weight of a polyether polyol and / or a polycarbonate polyol The press sleeve or conveyor belt according to claim 1, comprising the same.

13. The crosslinking agent component is based on the total weight of the polyurethane - 2 to 15% by weight of 1,6 - hexanediol, - 0.01 to 2% by weight of C １～６ alkyl monohydroxy monoamine, - 0.01 to 2% by weight of an aliphatic diamine selected from the group consisting of ethylenediamine, 2,2,4 - trimethyl - 1,6 - hexanediamine, 2,4,4 - trimethyl - 1,6 - hexanediamine and hexamethylenediamine, - 0.001 to 1% by weight of 1,4 - diazabicyclo(2.2.2)octane and / or an organometallic compound, and - 0.1 to 15% by weight of a polyether polyol The press sleeve or conveyor belt according to claim 12, comprising the same.

14. The crosslinking agent component is based on the total weight of the polyurethane - 2 to 15% by weight of 1,6 - hexanediol, - 0.01 to 2% by weight of monoethanolamine, - 0.01 to 2% by weight of hexamethylenediamine, - 0.001 to 1% by weight of 1,4 - diazabicyclo(2.2.2)octane and / or an organometallic compound, and - 0.1 to 15% by weight of polytetramethylene ether glycol The press sleeve or conveyor belt according to claim 12, comprising the same.

15. The press sleeve or conveyor belt according to claim 1, wherein the polyol component contains at least one polycarbonate polyol.

16. The polycarbonate polyol has the general formula (IV): -(O-R １ -O-C(O)) ｎ３ -O- (IV) where R １ is selected from a linear C １ - C ２０ alkylene group and a branched C １ - C ２０ alkylene group, and n ３ is an integer of at least 3, the press sleeve or conveyor belt according to claim 14.

17. The press sleeve or conveyor belt according to claim 1, wherein the polyurethane does not contain an aliphatic triol compound, preferably does not contain a triol compound.

18. A shoe press for dewatering a fiber web, particularly a paper web, cardboard web, tissue web or pulp web, comprising a press roll having a press sleeve according to any one of claims 1 to 17.

19. A machine for manufacturing or processing a fiber web, particularly a paper machine, cardboard paper machine or tissue paper machine, comprising a conveyor belt according to any one of claims 1 to 17.

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