Press sleeve or conveyor belt for shoe press with improved characteristics

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, particularly for a shoe press press roll for dewatering fiber webs, especially paper webs, cardboard webs, tissue paper webs or pulp webs, and more particularly to a conveyor belt for a machine for manufacturing or processing fiber webs, particularly a paper machine, cardboard machine or tissue paper machine, wherein the press sleeve or conveyor belt comprises at least one layer containing polyurethane. Furthermore, the present invention relates to a method for manufacturing the press sleeve or conveyor belt, a corresponding press sleeve and a corresponding conveyor belt.

[0002] Press rolls are used in various types of presses, for example, in the form of shoe rolls in shoe presses, which are used particularly for dewatering fibrous webs such as paper webs. This type of shoe press consists of a shoe roll and a counter roll, with a press nip formed between them. Here, the shoe roll consists of a fixed, i.e., non-rotating press element, i.e., the shoe, and a flexible press sleeve surrounding the shoe. Typically, the shoe is supported by a yoke that holds it in place and is pressed against the surrounding press sleeve by a hydraulic press element. Here, an oil film is usually formed between the shoe and the press sleeve for lubrication. Because the shoe is designed to be concave on the side facing the counter roll, the press nip is relatively long, about 20 times longer than that of a conventional press consisting of two rotating rolls.

[0003] During the operation of the shoe press, the fiber web is guided through the press nip along with one or two press felts. The pressure acting on the fiber web within the press nip causes a liquid to be expelled from the web. This liquid, in addition to water, contains dissolved and undissolved compounds such as fibers, fiber fragments, fillers, and / or additives. This liquid is temporarily absorbed into recesses provided on the press felt and press sleeve surfaces. After exiting the press nip, the liquid absorbed by the press sleeve is released from the press sleeve, which then re-enters the press nip. Additionally, water absorbed by the press felt is removed by a suction element after exiting the press nip. Due to the relatively long press nip created by the concave design of the shoe, such a shoe press achieves much better dewatering of the fiber web compared to a press consisting of two rotating rolls, resulting in a correspondingly shorter subsequent heat drying time. In this way, particularly gentle dewatering of the fiber web is achieved.

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

[0005] To at least partially satisfy these diverse requirements, such press sleeves are typically made of fiber-reinforced polyurethane, i.e., composite materials in which fiber laid webs or fiber fabrics are embedded in a matrix of cross-linked polyurethane. In this case, both single-layer press sleeves and corresponding multi-layer press sleeves are known.

[0006] International Publication No. 2015 / 086555 describes a press sleeve containing polyurethane, which is obtained by the reaction of a prepolymer formed from phenylenediisocyanate and polytetramethylene glycol. This reaction is carried out in the presence of a crosslinking agent component, which may include one or more of several different compounds.

[0007] From European Patent Application Publication No. 2284314, 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 a reaction product of a prepolymer made from an isocyanate component containing 55-100 mol% p-phenylenediisocyanate and a polyol, and a crosslinking agent component containing 65-100 mol% of one or more specific polyamines. The polyol is preferably polytetramethylene glycol.

[0008] From European Patent No. 2737124, a press sleeve or conveyor belt for shoe pressing is known, the press sleeve or conveyor belt comprising at least one layer containing crosslinked polyurethane, the crosslinked polyurethane can be obtained by a process of reacting a prepolymer, which is a reaction product of an isocyanate component containing methylenediphenyl diisocyanate and a polyol component containing a polycarbonate polyol, with a crosslinking agent component containing at least one polyol having a weight-average molecular weight of more than 1,000 g / mol.

[0009] International Publication No. 2017 / 129328 describes a press sleeve for shoe presses, comprising at least one layer containing a crosslinked polyurethane, the crosslinked polyurethane comprising a prepolymer formed from phenylenediisocyanate and a polyol, the prepolymer being crosslinked by reaction with a crosslinking agent component, the crosslinking agent component comprising 1,4-butanediol or 1,4-hydroquinone bis(2-hydroxyethyl) ether, and further aliphatic diamines and alkanolamines.

[0010] The press sleeves known from the last listed publications have relatively high resistance to water and chemicals, but there is room for improvement in their mechanical properties, particularly their hardness, modulus of elasticity, abrasion resistance, wear resistance, and swelling in water.

[0011] Therefore, the object of the present invention is to provide a press sleeve or conveyor belt having improved mechanical properties, in particular improved hardness, improved modulus of elasticity, improved abrasion resistance, improved wear resistance, and improved swelling in water.

[0012] According to the present invention, the problem is a press sleeve or conveyor belt for a press roll of a shoe press for dewatering a press roll of a press roll, in particular for dewatering a press roll of a press roll of a press roll, in particular for dewatering a press roll of a press roll of a press roll of a press roll, in particular for a press roll of a press roll of a press roll of a press roll of a press roll of a press roll, in particular for a press roll of a press roll of a press roll of a press roll of a press roll, in particular for a press roll of a press roll of a press roll of a press roll, in particular for a press roll of a press roll of a press roll of a press roll, in particular for a press roll of a press roll of a press roll of a press roll, in particular for a press roll of a press roll of a press roll of a press roll, in particular for a press roll of a press roll of a press roll of a press roll, in particular for a press roll of a press roll of a press roll of a press roll, in particular for a press roll of a press roll of a press roll of a press roll, in particular for dewatering dewatering a press roll of a press roll of a press roll of a press roll, in particular for 6~14 This is solved by providing a press sleeve or conveyor belt containing diol.

[0013] Surprisingly, within the scope of the present invention, a prepolymer formed from the reaction product of PPDI and a polyol component comprising at least one polyether polyol and / or at least one polycarbonate polyol is made into a prepolymer with at least one relatively long-chain diol, i.e., C 6~14It was found that polyurethane layers obtained by crosslinking with a crosslinking agent component containing a diol, for example, 1,6-hexanediol, exhibited improved hardness, improved modulus of elasticity, improved abrasion resistance, improved wear resistance, and improved (i.e., lower) swelling in water and hydrogen peroxide compared to the corresponding conventional polyurethane layers crosslinked with 1,4-butanediol. Furthermore, it was surprising that such polyurethane layers also exhibited good other required properties, such as excellent crack resistance, excellent crack growth resistance, and high resistance to chemicals, particularly water, oil, acids, bases, and solvents. Indeed, in addition to 1,4-butanediol and other crosslinking agents, hexanediol, heptanediol, octanediol, etc., are occasionally listed in publications as possible crosslinking agents for polyurethanes based on, for example, 4,4'-methylenediphenyl isocyanate (MDI), but there is no mention 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 know that long-chain crosslinking agents, i.e., C, such as 1,6-hexanediol, are also useful. 6~14 The aforementioned advantages are particularly surprising, as one would expect that the diol would worsen the separation of hard and soft segments compared to 1,4-butanediol, thus lowering the density of the hard segments, resulting in lower hardness, increased swelling in water, and consequently worsening the abrasion resistance of the polyurethane produced from it. While we do not wish to be bound by any theory, the aforementioned favorable properties are due to the longer chain of C compared to 1,4-butanediol. 6~14 This is thought to be due to the diol increasing the proportion of hard segments in the polyurethane.

[0014] According to the present invention, the crosslinking agent component of the polyurethane in 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 It contains a diol. Therefore, C 6~14The diol can be the corresponding diol having only terminal hydroxyl groups, the corresponding diol having only internal hydroxyl groups, or the corresponding diol having one terminal hydroxyl group and one internal hydroxyl group.

[0015] However, particularly, good results are obtained when the crosslinking agent component of the polyurethane is the corresponding diol having only terminal hydroxyl groups, i.e., the diol according to formula (I) HO-(CH2) x -OH (I) 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 the general formula (I) is an integer that is a multiple of 2, i.e., 6, 8, 10, 12 or 14. Most preferably, x in the general formula (I) is 6, i.e., the diol is 1,6 - hexanediol.

[0017] In order to obtain the above effects of the present invention at a particularly high level, it is proposed in a development form of the concept of the present invention that the crosslinking agent component contains 2 to 15% by weight, preferably 3 to 11% by weight, more preferably 4 to 10% by weight, particularly preferably 5 to 7% by weight of C 6~14 diol, preferably the diol according to the general formula (I). Particularly, it is preferable that the crosslinking agent component contains 2 to 15% by weight, preferably 3 to 11% by weight, more preferably 4 to 10% by weight, particularly preferably 5 to 7% by weight of 1,6 - hexanediol.

[0018] The stoichiometric H / NCO, i.e., the molar ratio of the crosslinking agent component to the prepolymer, is advantageously 1.15 to 0.85, particularly preferably 1.1 to 1.0.

[0019] To adjust the viscosity of the newly crosslinked polyurethane to a viscosity suitable for the production of press sleeves or conveyor belts, particularly a viscosity sufficiently high for the workability to form press sleeves or conveyor belts, the crosslinking agent component is C 6~14 It is proposed in a development of the concept of the present invention that, in addition to the diol, at least one alkanolamine is included.

[0020] Particularly, good results are obtained when at least one alkanolamine is a C 1~6 alkyl monohydroxy monoamine.

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

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

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

[0024] Advantageously, the crosslinking agent component contains 0.01 to 15 mol%, preferably 5 to 10 mol% of alkanolamine based on the total weight of the crosslinking agent component.

[0025] To adjust the viscosity of the newly crosslinked polyurethane to a viscosity suitable for the manufacture of press sleeves or conveyor belts, particularly a viscosity sufficiently high for processability in forming press sleeves or conveyor belts, it is also possible to add at least one aliphatic diamine to the crosslinking agent component instead of the aforementioned alkanolamine. Furthermore, to adjust the desired viscosity, the crosslinking agent component may contain both at least one alkanolamine and at least one aliphatic diamine.

[0026] Examples of suitable aliphatic diamines are aliphatic 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), and mixtures thereof.

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

[0028] According to a more preferred embodiment of the present invention, the crosslinking agent component comprises an aliphatic diamine in an amount of 0.01 to 2% by weight, preferably 0.05 to 1% by weight, and particularly preferably 0.1 to 0.5% by weight, based on the total weight of the polyurethane.

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

[0030] In an advanced form of the present invention, the crosslinking agent component is C 6~14 It is proposed that the mixture include at least one catalyst in addition to the diol. The addition of at least one catalyst is preferable to achieve sufficiently rapid crosslinking of the polyurethane, so that the polyurethane does not remain liquid for an excessively long time during processing and no corrugation occurs on the surface of the press sleeve or conveyor belt. The addition of a catalyst to the crosslinking agent component is preferable because the crosslinking agent component contains at least one C 6~14It is preferable whether or not it 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 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), triethylamine, and mixtures thereof. Similarly good results are obtained when at least one catalyst includes 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 preferred is at least one catalyst, which is 1,4-diazabicyclo(2.2.2)octane (DABCO) and / or bismuth neodecanoate.

[0034] According to a more preferred embodiment of the present invention, the crosslinking agent component comprises a tertiary amine compound and / or organometallic compound in an amount of 0.01 to 1% by weight, preferably 0.02 to 0.5% by weight, and particularly preferably 0.05 to 0.2% by weight, based on the total weight of the polyurethane.

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

[0036] In an advanced form of the present invention, the crosslinking agent component is at least one C 6~14 In addition to the diol, it is proposed that the mixture include at least one polyether polyol and / or polycarbonate polyol. This addition is because the crosslinking agent component is at least one C 6~14It is preferable whether or not the diol contains at least one alkanolamine and / or at least one aliphatic diamine and / or at least one catalyst. The hardness of the polyurethane can be finely adjusted by adding a polyether polyol or a polycarbonate polyol.

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

[0038] In particular, the crosslinking agent component is of general formula (III): -(OR 1 -OC(O)) n2 -O- (III) Good results are obtained when the mixture contains at least one polycarbonate polyol having the following properties, where R 1 is a linear C1-C 20 Alkylene group and branched C1-C 20 Selected from alkylene groups, n² is an integer between 3 and 30.

[0039] According to an alternative embodiment, the polycarbonate polyol may also have different alkylene groups, for example, two, three, or four different alkylene groups. For example, the polycarbonate polyol may have a first C1-C 20 Alkylene group A, for example, a linear C3 alkylene group, and a second C1-C group different from the first alkylene group. 20 It may have an alkylene group B, for example, a linear C6 alkylene group. In that case, these two groups can be arranged alternately, in blocks, or randomly, for example, ABAB, AAAB, AABB, BBAA, or BAAA.

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

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

[0042] In an advanced form of the present invention, the crosslinking agent component is, relative to the total weight of the polyurethane - 2-15% by weight of C 6~14 Diol, - 0.01-2% by weight of alkanolamines, - 0.01-2% by weight of aliphatic diamines, - 0.001 to 1% by weight of tertiary amine compounds and / or organometallic compounds, and - 0.1 to 15% by weight of polyether polyols and / or polycarbonate polyols It is proposed that this be included.

[0043] In particular, the crosslinking agent component is proportional to the total weight of the polyurethane. - 2-15% by weight of 1,6-hexanediol, - 0.01-2% by weight of C 1~6 Alkyl monohydroxymonoamine, - 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 - 0.1-15% by weight of polyether polyol Good results are obtained when it is included.

[0044] Particularly preferably, the crosslinking agent component is in proportion to the total weight of the polyurethane. - 2-15% by weight of 1,6-hexanediol, - 0.01-2% by weight of monoethanolamine, - 0.01-2% 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 particularly preferred embodiment of the present invention, the crosslinking agent component of the polyurethane press sleeve or conveyor belt is free of aliphatic triol compounds, preferably free of triol compounds such as trimethylenepropane (TMP) altogether. The addition of triol compounds leads to a decrease in the elastic modulus of the polyurethane, a decrease in crack resistance, a decrease in tear propagation resistance, and a lack of abrasion resistance, presumably because these compounds interfere with the formation of hard segments in the polyurethane.

[0046] According to the present 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, like any polyether polyol of the crosslinking agent component, can be selected from the group consisting of polytetramethylene ether glycol (PTMEG), polypropylene glycol (PPG), polyethylene glycol (PEG), polyhexamethylene ether glycol, and mixtures thereof.

[0047] According to a more 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. PPDI, PTMEG and C as a crosslinking agent. 6~14Specific combinations with diols provide particularly good improvements and balances in the hardness, modulus of elasticity, abrasion resistance, wear resistance, and swelling properties of polyurethane press sleeves or conveyor belts.

[0048] In particular, good results are obtained when PTMEG has a weight-average molecular weight of 100 to 10,000 g / mol, preferably 500 to 5,000 g / mol, especially preferably 1,000 to 3,000 g / mol, and most preferably 1,000 to 2,500 g / mol. The molecular weight can be determined by gel permeation chromatography against a polystyrene standard. However, according to the present invention, it is preferable to determine the weight-average molecular weight of the structural unit by its hydroxyl value, that is, by the amount of potassium hydroxide in milligrams equivalent to the amount of acetic acid bound when acetylating 1 g of the substance. The hydroxyl value can be determined by back titration in accordance with DIN 53240 and is given in mg KOH / g units. The weight-average molecular weight can be obtained by dividing 112,200 by the hydroxyl value.

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

[0050] Advantageously, the polycarbonate polyol component, whether used alone or in combination with a polyether polyol, is governed by general formula (IV): -(OR 2 -OC(O)) n3 -O- (IV) It is, and here, R 2 is a linear C1-C 20 Alkylene group and branched C1-C 20 Selected from 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, two, three, or four different alkylene groups. For example, the polycarbonate polyol may have a first C1-C 20 Alkylene group A, for example, a linear C3 alkylene group, and a second C1-C group different from the first alkylene group. 20 It may have an alkylene group B, for example, a linear C6 alkylene group. In that case, these two groups can be arranged alternately, in blocks, or randomly, for example, ABAB, AAAB, AABB, BBAA, or BAAA.

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

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

[0054] For the reasons stated above, it is preferable that neither the crosslinking agent component nor the polyurethane itself contains aliphatic triol compounds, and more preferably, it is preferable that the polyurethane itself does not contain triol compounds.

[0055] Furthermore, it is preferable that the polyurethane layer of the press sleeve or conveyor belt, and, if multiple polyurethane layers exist, all polyurethane layers, contain only one type of polyurethane, that is, only polyurethane formed from a prepolymer by the reaction of the prepolymer with a crosslinking agent component.

[0056] The press sleeve or conveyor belt according to the present invention may be designed as a single-layer or double-layer structure. In the case of a double-layer structure, at least the outer layer is made of the aforementioned polyurethane.

[0057] In an advanced form of the present invention, it is proposed that a press sleeve or conveyor belt is constructed of two layers, wherein the outer layer is made of the aforementioned polyurethane, and the inner layer is made of another polyurethane, and the polyurethane of the inner layer forms a matrix into which a fiber laid web or fiber fabric is embedded.

[0058] A further subject of the present invention is a shoe press for dewatering fibrous webs, particularly paper webs, cardboard webs, tissue paper webs or pulp webs, the shoe press comprising the aforementioned press sleeve.

[0059] Furthermore, the present invention relates to a machine for manufacturing or processing fiber webs, in particular a paper machine, a cardboard machine, or a thin paper machine, which is equipped with the aforementioned conveyor belt.

[0060] Finally, the present invention relates to a method for manufacturing the aforementioned press sleeve or conveyor belt, and furthermore: a) A step of providing at least one rotatably mounted winding mandrel, b) A step of providing the aforementioned crosslinking agent component, c) A step of providing a prepolymer as a reaction product of PPDI and the aforementioned polyol component, d) A process of mixing a prepolymer and a crosslinking agent component to produce polyurethane, e) A step of spreading a mixture of prepolymer and crosslinking agent on the surface of a winding mandrel to form at least one polymer layer of a press sleeve or conveyor belt, f) A step of curing at least one polymer layer, g) The process of removing the press sleeve or conveyor belt manufactured in this manner from the winding mandrel. Regarding methods including

[0061] The present invention will be described below merely illustratively, with reference to the accompanying drawings, based on advantageous embodiments. [Brief explanation of the drawing]

[0062] [Figure 1] This is a schematic diagram of a shoe press equipped with a press sleeve according to one embodiment of the present invention. [Figure 2] This is a schematic diagram of the press section of a paper machine equipped with a shoe press and a conveyor belt, according to an example of one embodiment of the present invention.

[0063] Figure 1 shows a shoe press 10, which comprises a shoe roll 12 and a counter roll 14. The counter roll 14 consists of a rotating cylindrical roll, while the shoe roll 12 consists of a shoe 16, a stationary yoke 18 that supports 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). Because the shoe 16 is designed to be concave on the side facing the counter roll 14, the press nip 22 is relatively long.

[0064] The shoe press 10 is particularly suitable for dewatering fibrous webs 24, such as paper webs. During operation of the shoe press, the fibrous web 24 is guided through the press nip 22 along with one or two press felts 26,26', and the liquid that comes out of the fibrous web 24 due to the pressure acting on it within the press nip 22 contains not only water but also dissolved and undissolved compounds such as fibers, fiber fragments, fillers and / or additives, and this liquid is temporarily absorbed by the press felts 26,26' and recesses (not shown) provided on the surface of the press sleeve. After coming out of the press nip 22, the liquid absorbed by the press sleeve 20 is released from the press sleeve 20, and then the press sleeve 20 re-enters the press nip 22. In addition, the water absorbed by the press felts 26,26' is removed by a suction element after coming out of the press nip 22.

[0065] Due to the concave design of the shoe 16 on the side facing the counter roll 14, the press nip 22 is relatively long. As a result, such a shoe press 10 achieves significantly better dewatering of the fiber web 24 compared to a press consisting of two rotating rolls, and consequently, the subsequent heat drying can be shortened. In this way, particularly gentle dewatering of the fiber web 24 is achieved.

[0066] Figure 2 shows a cross-section of the press section of a paper machine equipped with a shoe press 10. Here, similar to the embodiment shown in Figure 1, the shoe press 10 comprises a shoe roll 12 having a press sleeve 20 and a press element or shoe 16, and a counter roll 14, with a press nip formed between the shoe 16 and the counter roll 14. Furthermore, this part of the paper machine is equipped with two suction rolls 28, 28' and two deflection rolls 30, 30'. During operation of the paper machine, the felt 26 guided by the suction rolls 28, 28' picks up the fiber web 24 with the suction rolls 28 and guides it through the press nip. Furthermore, below the felt 26 guiding the fiber web 24, a conveyor belt or transport belt 32 guided by the deflection rolls 30, 30' is guided through the press nip, in which case the transport belt 32 takes over the fiber web 24 from the felt 26 at the press nip and removes it from the press nip with the deflection rolls 30'. The pressure acting on the fiber web 24 within the press nip causes liquid to be discharged from the fiber web. This liquid, in addition to water, contains dissolved and undissolved compounds such as fibers, fiber fragments, fillers, and / or additives, and is temporarily absorbed into recesses provided on the felt 26 and the surface of the press sleeve. After leaving the press nip, the liquid absorbed by the press sleeve 20 is released from the press sleeve 20, and then the press sleeve 20 re-enters the press nip. The water absorbed by the felt 26 is removed by a suction element provided on the suction roll 28' after leaving the press nip. Due to the relatively long press nip created by 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 rolls, and consequently, the subsequent heat drying can be shortened. In this way, particularly gentle dewatering of the fiber web 24 is achieved.

[0067] The present invention will be described merely illustratively below, with reference to non-limiting embodiments for the sole purpose of explanation, based on advantageous embodiments.

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

[0069] Furthermore, the crosslinking agent component was prepared with the following composition: 84.9 mol% of 1,6-hexanediol (equivalent to 72.3% by weight of the crosslinking agent component), 1.3 mol% PTMEG, 2000 g / mol (equivalent to 19.4% by weight of the crosslinking agent component), 1.6 mol% DABCO (equivalent to 1.3 wt% of the crosslinking agent component), 8.0 mol% monoethanolamine (equivalent to 3.5% by weight of the crosslinking agent component), 4.2 mol% hexamethylenediamine (equivalent to 3.5% by weight of the crosslinking agent component).

[0070] As is publicly known and described, for example, in German Patent Application Publication No. 102017115084, a press sleeve is manufactured using a rotatable winding mandrel, in which a prepolymer and a crosslinking agent component are supplied separately to a casting device equipped with a mixing chamber and a casting nozzle downstream thereof, the prepolymer and the crosslinking agent component are continuously mixed together in the mixing chamber, and the mixture thus produced is then continuously applied to the rotating winding mandrel by the casting nozzle. Here, the prepolymer and the crosslinking agent component are mixed together at a ratio of 9.89 g of crosslinking agent component per 100 g of prepolymer.

[0071] Furthermore, to measure the properties of polyurethane, prepolymer and crosslinking agent components were mixed together, and polyurethane sheets were manufactured by casting the resulting mixture 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 increase in water in %, weight increase in hydrogen peroxide, N / mm 2Modulus of elasticity (E-Modul) in units (measured according to DIN 53504) and N / mm 2 The F (10%) in units was measured (according to DIN 53504). The measurement results are summarized in the table below.

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

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

[0074] Comparative Example 2 The procedure was the same as in Example 1, except that the following crosslinking agent 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 mol% 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 Rolls 16 Shoe 18 Stationary yoke 20 Press Sleeves 22 Pressnips 24 Textile Web 26,26' Press Felt 28,28' Suction Roll 30,30' Deflection Roll 32 Conveyor belts / transport belts

Claims

1. Press sleeves or conveyor belts for press rolls of shoe presses, particularly for dewatering fiber webs, especially paper webs, cardboard webs, tissue paper webs or pulp webs, especially conveyor belts for machines for manufacturing or processing fiber webs, particularly paper machines, cardboard machines or tissue paper machines, wherein the press sleeve or conveyor belt comprises at least one layer comprising polyurethane, the polyurethane being formed by reacting a prepolymer with a crosslinking agent component, the prepolymer being a reaction product of 1,4-phenylenediisocyanate (PPDI) with a polyol component comprising at least one polyether polyol and / or at least one polycarbonate polyol, and the crosslinking agent component being C ６～１４ Contains diol, The aforementioned crosslinking agent component is of formula (I) HO-(CH 2 ) x -OH (I) It contains a diol by which, where X is an integer from 6 to 14, The aforementioned crosslinking agent component does not contain a triol compound. Press sleeve or conveyor belt.

2. The press sleeve or conveyor belt according to claim 1, wherein X is 6, 8, 10, 12, or 14.

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

4. The crosslinking agent component is C according to formula (I) in an amount of 2 to 15% by weight relative to the total weight of the polyurethane. ６～１４ A press sleeve or conveyor belt according to claim 1, comprising a diol.

5. The press sleeve or conveyor belt according to claim 1, wherein the crosslinking agent component further comprises at least one alkanolamine.

6. The press sleeve or conveyor belt according to claim 1, wherein the crosslinking agent component further comprises at least one aliphatic diamine.

7. The press sleeve or conveyor belt according to claim 1, wherein the crosslinking agent component further comprises at least one catalyst.

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

9. The press sleeve or conveyor belt according to claim 1, wherein the polyol component comprises polytetramethylene glycol as a polyether polyol.

10. The press sleeve or conveyor belt according to claim 9, wherein the polytetramethylene glycol has a weight-average molecular weight of 100 to 10,000 g / mol.

11. The crosslinking agent component is, relative to the total weight of the polyurethane. - 2 to 15% by weight of the above C ６～１４ Diol, - 0.01 to 2% by weight of alkanolamines, - 0.01 to 2% by weight of aliphatic diamines, - 0.001 to 1% by weight of tertiary amine compounds and / or organometallic compounds, and - 0.1 to 15% by weight of polyether polyols and / or polycarbonate polyols A press sleeve or conveyor belt according to claim 1, comprising:

12. The crosslinking agent component is, relative to 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 monohydroxymonoamine, - 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 organometallic compounds, and - 0.1 to 15% by weight of polyether polyol A press sleeve or conveyor belt according to claim 11, including the above.

13. The crosslinking agent component is, relative to 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 organometallic compounds, and - 0.1 to 15% by weight of polytetramethylene ether glycol A press sleeve or conveyor belt according to claim 11, including the above.

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

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

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

17. A shoe press for dewatering a fiber web, in particular a paper web, a cardboard web, a tissue paper web or a pulp web, comprising a press roll having a press sleeve according to any one of claims 1 to 16.

18. A machine for manufacturing or processing fiber webs, in particular a paper machine, a cardboard machine or a thin paper machine, comprising a conveyor belt according to any one of claims 1 to 16.

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