Papermaking belt and method of manufacturing a papermaking belt

Abstract

The present invention provides a papermaking belt and a manufacturing method thereof, which suppresses changes in the properties of the surface of a resin layer during use. A papermaking belt for a papermaking machine has at least one resin layer containing a resin, and the surface of the resin layer is brought into contact with a metal plate having a surface roughness of 0.10 μm or less in a warm water bath at 70±5°C for 20 hours under a pressure of 100±3 Kg / cm 2 The surface roughness after the contact is 40% or more relative to the surface roughness of the surface of the resin layer before the contact.

Description

TECHNICAL FIELD

[0001] The present application relates to a papermaking belt and a manufacturing method of a papermaking belt. BACKGROUND

[0002] A papermaking machine is used to remove water from a paper stock, and generally has a wire section, a press section, and a drying section. The wire section, the press section, and the drying section are arranged in this order in the conveying direction of the wet paper.

[0003] In each section of such a papermaking machine, various papermaking belts are used for conveying the wet paper and pressing the wet paper, and the like. As such papermaking belts, for example, a wet paper conveying belt (conveyor belt) for conveying and transferring the wet paper, a shoe press belt used in a shoe press mechanism, and the like can be listed.

[0004] In terms of the press section using the wet paper conveying belt to transfer the wet paper, at present, as a papermaking machine, a closed-draught papermaking machine is known which transfers the wet paper by closed-draught. In the press section of the closed-draught papermaking machine, the wet paper is conveyed while being placed on a papermaking felt or a wet paper conveying belt, and thus there is no site where the wet paper travels alone, and thus paper breakage is prevented. Thus, the closed-draught papermaking machine is excellent in terms of high-speed running capability and stability of operation.

[0005] On the other hand, in order to properly transfer the wet paper in the closed-draught papermaking machine, it is required that the wet paper conveying belt has a function of conveying the wet paper in a state where the wet paper is stuck (wet paper adhesion), and a function of being able to smoothly peel the wet paper when transferring the wet paper to the rear section (wet paper peelability). Thus, in order to realize the above-mentioned opposite functions, the adhesion of the wet paper carrying surface of the wet paper conveying belt to the wet paper is an important factor.

[0006] In Patent Documents 1 and 2, a wet paper conveying belt is disclosed in which the wet paper contact surface of the resin layer carrying the wet paper has an arithmetic surface roughness within a prescribed range according to the basis weight of the raw paper of the wet paper and the swelling rate of the resin constituting the resin layer with respect to water.

[0007] Prior Art Documents

[0008] Patent Documents

[0009] Patent Document 1: Japanese Patent Application Publication No. 2014-62337

[0010] Patent Document 2: Japanese Patent Application Publication No. 2014-62338 SUMMARY

[0011] Problems to be Solved by the Invention

[0012] Further, in a papermaking machine, wet paper is continuously transported at a high speed (for example, at a speed of 1000 m / min or more). In such a severe environment, the papermaking belt is worn out as it travels on the wet paper transporting belt, or is pressed in a press mechanism, thereby causing a change in the properties of the surface thereof. In addition, dirt is attached to the papermaking belt as it is used. As a result, the wet paper adhesion and the wet paper peelability of the papermaking belt change from the initial state. In this case, if the wet paper transporting belt is used for a long period of time, a problem can occur in that the wet paper cannot be properly transferred. In the conventional papermaking belt, there is room for improvement in this regard.

[0013] Therefore, an object of the present application is to provide a papermaking belt and a manufacturing method thereof, which suppresses a change in the properties of the surface of a resin layer during use.

[0014] Approach to solving the problem

[0015] The present inventors have made intensive studies in order to achieve the above object, and as a result, have focused on the use of a papermaking belt in a wet state in a papermaking machine. Further, the present inventors have found that the amount of change in the surface roughness of a resin layer of a papermaking belt in a wet state is related to a change in the properties of the surface of the resin layer. Further, it has been found that the use of a polycarbodiimide contributes to the maintenance of the surface roughness of the resin layer of a papermaking belt in a wet state, and the present application has been completed as a result of further studies.

[0016] The gist of the present application is as described below.

[0017] [1] A papermaking belt for a papermaking machine, having at least one resin layer containing a resin,

[0018] The surface of the resin layer is brought into abutment with a metal plate having a surface roughness of 0.10 μm or less in a warm water bath at 70 ± 5°C for 20 hours at a pressure of 100 ± 3 Kg / cm 2 The surface roughness after the abutment is 40% or more relative to the surface roughness of the surface of the resin layer before the abutment.

[0019] [2] The papermaking belt according to [1], wherein the resin of at least the vicinity of the surface of the resin layer is crosslinked by a polycarbodiimide.

[0020] [3] A papermaking belt for a papermaking machine, having at least one resin layer containing a resin,

[0021] The resin of at least the vicinity of the surface of the resin layer is crosslinked by a polycarbodiimide.

[0022] [4] The papermaking belt according to any one of [1] to [3], wherein the surface roughness of the surface of the resin layer in a wet state is 0.3 μm or more and 20 μm or less.

[0023] [5] The papermaking belt according to any one of [1] to [4], wherein the resin of at least the vicinity of the surface of the resin layer contains an N-acylurea bond and / or an isourea bond.

[0024] [6] The papermaking belt according to any one of [1] to [5], wherein the resin layer contains a polyurethane resin.

[0025] [7] The papermaking belt according to [6], wherein the polyurethane resin contains an aqueous polyurethane resin.

[0026] [8] The papermaking belt according to any one of [1] to [7], wherein the surface of the resin layer contains a wet paper contact surface.

[0027] [9] The papermaking belt according to any one of [1] to [8], wherein the papermaking belt is a wet paper conveying belt.

[0028]

[10] The papermaking belt according to any one of [1] to [8], wherein the papermaking belt is a shoe press belt.

[0029]

[11] A method for manufacturing a papermaking belt, comprising a step of forming at least one resin layer,

[0030] In the step, the resin of at least the vicinity of the surface of the resin layer formed is crosslinked by a polycarbodiimide.

[0031] Effects of the Invention

[0032] With the above configuration, it is possible to provide a papermaking belt and a method for manufacturing the papermaking belt, which suppresses changes in the properties of the surface of the resin layer during use. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 is a mechanical cross-sectional view showing a papermaking belt according to an embodiment of the present invention.

[0034] Figure 2 is a schematic view for explaining a preferred embodiment of a method for manufacturing a papermaking belt according to the present invention.

[0035] Figure 3 is a schematic view for explaining a preferred embodiment of a method for manufacturing a papermaking belt according to the present invention.

[0036] Figure 4 is a schematic view for explaining a preferred embodiment of a method for manufacturing a papermaking belt according to the present invention.

[0037] Figure 5 is a schematic view for explaining a preferred embodiment of a method for manufacturing a papermaking belt according to the present invention.

[0038] Figure 6 is a schematic view for explaining an example of a papermaking machine to which the papermaking belt according to the present application is applied.

[0039] Figure 7 is a schematic view for explaining an abutment process at the time of measuring the roughness retention rate of the surface of the resin layer.

[0040] Figure 8 is a schematic view of a device for evaluating the wet paper conveyability of a wet paper conveyance belt.

[0041] Explanation of Reference Numerals

[0042] 1: Wet paper conveyance belt

[0043] 11: First resin layer

[0044] 111: Wet paper contact surface

[0045] 13: Fiber-reinforced base material layer

[0046] 131: Fiber-reinforced base material

[0047] 15: Second resin layer

[0048] 151: Roll contact surface

[0049] 113, 133, 153: Resin DETAILED DESCRIPTION

[0050] Hereinafter, preferred embodiments of a papermaking belt and a manufacturing method of a papermaking belt according to the present application will be described in detail with reference to the drawings.

[0051] 1. Papermaking belt

[0052] First, a papermaking belt according to the preferred embodiments of the present application will be described.

[0053] Figure 1 is a mechanical cross-sectional view showing an example of a papermaking belt according to the preferred embodiments of the present application. Note that in the drawing, the sizes of the components are appropriately enlarged for convenience of explanation, and are not shown in accordance with the actual ratios and sizes of the components. Here, the above-mentioned cross machine direction (Cross Machine Direction) is also referred to as "CMD", and the machine direction (Machine Direction) is also referred to as "MD". In addition, although a wet paper conveyance belt is described as an example of a papermaking belt in the present embodiment, the papermaking belt according to the present application is not limited thereto.

[0054] Figure 1The wet paper conveying belt (papermaking belt) 1 shown in FIG. 1 is used for conveying and transferring the wet paper W in the press section of a papermaking machine. The wet paper conveying belt 1 is formed as an endless belt-like body. That is, the wet paper conveying belt 1 is a belt in a ring shape. Also, the wet paper conveying belt 1 is generally arranged in the machine direction (MD) of the papermaking system in the circumferential direction.

[0055] The wet paper conveying belt 1 has a fiber-reinforced base material layer 13, a first resin layer (wet paper carrying-side resin layer) 11 provided on one main surface on the outer surface side of the fiber-reinforced base material layer 13, and a second resin layer (roll-side resin layer) 15 provided on the other main surface on the inner surface side of the fiber-reinforced base material layer 13, and these layers are laminated to form the wet paper conveying belt 1. In addition, the first resin layer is a layer that forms the outer surface (outer circumferential surface) of the ring formed by the wet paper conveying belt 1.

[0056] The first resin layer 11 is a layer mainly composed of a resin 113, and is provided on one main surface of the fiber-reinforced base material layer 13.

[0057] The first resin layer 11 constitutes a wet paper carrying surface 111 for contacting and carrying the wet paper W on the main surface on the side opposite to the main surface engaged with the fiber-reinforced base material layer 13. That is, the wet paper conveying belt 1 is capable of carrying and conveying the wet paper W on the wet paper carrying surface 111 of the first resin layer 11.

[0058] In this embodiment, the wet paper carrying surface 111 of the first resin layer 11 is abutted against a metal plate 20 having a surface roughness of 0.10 μm or less in a warm water bath at 70 ± 5°C for 20 hours under a pressure of 100 ± 3 Kg / cm 2 The surface roughness of the wet paper carrying surface 111 after the abutment is 40% or more of the surface roughness of the wet paper carrying surface 111 of the first resin layer 11 before the abutment. Hereinafter, the ratio of the surface roughness of the wet paper carrying surface 111 after the abutment to the surface roughness of the wet paper carrying surface 111 of the first resin layer 11 before the abutment will be referred to as the roughness retention rate. The present inventors have found that the roughness retention rate of the wet paper carrying surface 111 in the wet state as above is related to the change in the properties of the wet paper carrying surface 111, and that if the roughness retention rate is 40% or more, the change in the properties of the wet paper carrying surface 111 of the wet paper conveying belt 1 can be suppressed.

[0059] Specifically, the surface roughness of the wet paper carrying surface 111 affects the function of conveying the wet paper in a state where the wet paper is attached (wet paper adhesion), the function of smoothly peeling the wet paper when transferring the wet paper to the rear section (wet paper peelability), and the like. On the other hand, generally, the surface roughness of the wet paper carrying surface 111 is measured immediately after production and before wetting. The present inventors have found that the surface roughness of the wet paper carrying surface 111 before wetting as described above is not actually equivalent to the surface roughness of the wet paper carrying surface 111 in the wet state when the wet paper conveyor belt 1 is used; and that the surface roughness of the wet paper carrying surface 111 changes over time when used, and that this is focused on. Further, it has been found that the retention rate of the roughness of the wet paper carrying surface 111 in the wet state as described above can be used as an index to grasp the change in the properties of the wet paper carrying surface 111 when used (specifically, the change in the wet paper adhesion and the wet paper peelability). Further, by making the retention rate of the roughness of the wet paper carrying surface 111 in the wet state 40% or more, the change in the wet paper adhesion and the wet paper peelability of the wet paper conveyor belt 1 can be suppressed, and thus the wet paper can be transferred stably for a long period of time.

[0060] The retention rate of the roughness of the wet paper carrying surface 111 of the wet paper conveyor belt 1 can be obtained as follows.

[0061] First, the surface roughness (arithmetic average roughness Ra) of the wet paper carrying surface 111 of the wet paper conveyor belt 1 before the abutting treatment described later is measured. The surface roughness of the wet paper carrying surface 111 of the wet paper conveyor belt 1 before the abutting treatment is measured in a wet state. First, a sample of the wet paper conveyor belt 1 is immersed in a constant-temperature water tank at 70 ± 5°C for 20 hours. Then, the surface roughness of the wet paper carrying surface 111 in the wet state is measured. The surface roughness can be measured using any method, such as contact measurement using a contact-type roughness meter, an atomic force microscope, or the like, and non-contact measurement using a white light interferometer, a laser microscope, or the like. Among these, contact measurement is preferable. Note that the temperature of the constant-temperature water tank can be within ± 5°C of 70°C.

[0062] Next, the wet paper carrying surface 111 of the first resin layer 11 is caused to abut against a metal plate having a surface roughness of 0.10 μm or less in a warm water bath at 70 ± 5°C for 20 hours under a pressure of 100 ± 3 Kg / cm 2 Note that the temperature of the warm water bath can be within ± 5°C of 70°C. In addition, the surface roughness of the metal plate can be 0.10 μm or less, and the material of the metal plate is not particularly limited.

[0063] Next, the surface roughness of the wet paper carrying surface 111 of the wet paper conveyance belt 1 after the abutment treatment is measured. This measurement can be performed in the same manner as the measurement of the surface roughness of the wet paper carrying surface 111 of the wet paper conveyance belt 1 before the abutment treatment. Note that the surface roughness can be measured directly after the abutment treatment without any special treatment. Alternatively, the sample of the wet paper conveyance belt 1 can be immersed in a constant-temperature water tank at 70 ± 5°C for 30 minutes, and then the surface roughness can be measured.

[0064] The retention rate of the roughness can be calculated using the following equation.

[0065] Roughness retention rate (%) = (surface roughness of the wet paper carrying surface 111 after the abutment treatment) / (surface roughness of the wet paper carrying surface 111 before the abutment treatment) x 100

[0066] The roughness retention rate of the wet paper carrying surface 111 of the wet paper conveyance belt 1 is preferably 40% or more, more preferably 50% or more, and even more preferably 60% or more. Thus, the adhesion and the peelability of the wet paper conveyance belt 1 to the wet paper W can be further suppressed from changing, and thus the wet paper W can be conveyed more stably for a longer period of time.

[0067] In addition, the arithmetic mean roughness Ra of the wet paper carrying surface 111 in the wet state based on JIS B0601 is not particularly limited, and is preferably 0.3 to 20 μm, more preferably 0.5 to 12.0 μm, and even more preferably 1 to 10 μm. Thus, the adhesion and the peelability of the wet paper conveyance belt 1 to the wet paper W are more excellent.

[0068] As the material of the resin 113 constituting the first resin layer 11, one or two or more kinds of thermosetting resins such as a polyurethane resin, an epoxy resin, an acrylic resin, or a thermoplastic resin such as a polyamide resin, a polyarylate resin, or a polyester resin can be used alone or in combination, and preferably a polyurethane resin can be used.

[0069] The polyurethane resin used in the resin 113 constituting the first resin layer 11 is not particularly limited, and for example, a polyurethane resin obtained by reacting a polyisocyanate compound with a polyol to obtain an urethane prepolymer having an isocyanate group at the terminal, and curing the urethane prepolymer together with a curing agent having an active hydrogen group can be used. In addition, anionic, nonionic, cationic, self-emulsifying, or forced-emulsifying water-based polyurethane resins can also be used.

[0070] In the above, the resin 113 constituting the first resin layer 11 preferably uses a water-based polyurethane resin. The water-based polyurethane resin is a resin formed using a water dispersion of a polyurethane resin. By constituting the wet paper carrying surface 111 of the first resin layer 11 using such a water-based polyurethane resin, the wet paper carrying surface 111 is made hydrophilic, and the adhesion of the wet paper W to the wet paper carrying surface 111 is improved. Thus, it is easier to control the adhesion and the peelability of the wet paper W by adjusting the surface roughness of the wet paper carrying surface 111 to control the unevenness. In addition, since the wet paper carrying surface 111 of the first resin layer 11 is hydrophilic, dirt is less likely to adhere when the wet paper conveyor belt 1 is used, and the change in the properties of the wet paper carrying surface 111 of the wet paper conveyor belt 1 is further suppressed.

[0071] In addition, in the present embodiment, the resin 113 constituting the first resin layer 11 is crosslinked by a crosslinking agent containing a polycarbodiimide. In this way, by crosslinking the resin in the vicinity of the wet paper carrying surface 111 using a crosslinking agent containing a polycarbodiimide, the water resistance and the durability of the wet paper carrying surface 111 can be improved, and the roughness retention rate of the wet paper carrying surface 111 can be easily achieved.

[0072] Hereinafter, the polyurethane resin and the crosslinking agent containing a polycarbodiimide used therein will be described in detail.

[0073] As described above, the polyurethane resin includes, for example, a polyurethane resin obtained by reacting a water-based polyurethane resin and / or a polyisocyanate compound with a polyol to obtain an urethane prepolymer having an isocyanate group at the terminal, and curing the urethane prepolymer together with a curing agent having an active hydrogen group to obtain a polyurethane resin. Note that the polyurethane resin is formed using a polyisocyanate compound, a polyol, and a curing agent as needed. Therefore, hereinafter, the polyisocyanate compound, the polyol, and the curing agent constituting the polyurethane resin will be described.

[0074] As the polyisocyanate compound, aromatic polyisocyanate compounds and aliphatic polyisocyanate compounds can be exemplified, and one kind thereof alone or two or more kinds thereof in combination can be used. As the aromatic polyisocyanate compound, for example, 2,4-toluene diisocyanate (2,4-TDI), 2,6-toluene diisocyanate (2,6-TDI), 4,4'-methylenebis(phenyl isocyanate) (MDI), p-phenylene diisocyanate (PPDI), dimethyl diphenyl diisocyanate (TODI), 1,5-naphthalene diisocyanate (NDI), 4,4-dibenzyl diisocyanate (DBDI), xylylene diisocyanate (XDI), tetramethyl m-xylylene diisocyanate (TMXDI), polymethylene polyphenyl polyisocyanate (polymeric MDI), and the like can be exemplified. The aliphatic polyisocyanate compound is not particularly limited, and for example, 1,6-hexamethylene diisocyanate (HDI), chain aliphatic polyisocyanates such as 1,5-pentamethylene diisocyanate, and alicyclic polyisocyanates such as isophorone diisocyanate (IPDI), dicyclohexylmethane-4,4'-diisocyanate (H12MDI), 1,3-cyclohexyl diisocyanate, 1,4-cyclohexyl diisocyanate (CHDI), and 1,4-bis-(isocyanatomethyl)cyclohexane (H6XDI) can be exemplified, and one kind thereof alone or two or more kinds thereof in combination can be used.

[0075] Note that the aqueous polyurethane resin is usually composed of an aliphatic polyisocyanate compound. In the above, the polyurethane resin preferably contains one or more selected from the group consisting of isophorone diisocyanate (IPDI), dicyclohexylmethane-4,4'-diisocyanate (H12MDI), and 1,6-hexamethylene diisocyanate (HDI).

[0076] The polyol compound is not particularly limited, and for example, long-chain polyol compounds such as polycaprolactone polyol, polyester polyols such as polyethylene adipate, polyether polyols such as polyethylene glycol, polypropylene glycol, polyhexamethylene ether glycol, and polytetramethylene ether glycol (PTMG), polycarbonate polyols such as polycarbonate diol, polyether carbonate diol, trimethylolpropane, polybutadiene polyol, perfluoropolyether polyol, and silicon glycol can be exemplified, and one kind thereof alone or two or more kinds thereof in combination can be used.

[0077] It should be noted that polycarbonate polyols are not particularly limited, and examples include polycarbonate polyols synthesized from polycarbonate polyol raw material polyols and polycarbonate sources. Furthermore, polycarbonate polyol raw material polyols are not particularly limited, and examples include straight-chain or branched alkylene glycols with 2 or more but less than 20 carbon atoms, and hydroxyl-containing cyclic hydrocarbons with 2 or more but less than 20 carbon atoms, etc., and one or more of these can be used alone or in combination. Examples of straight-chain alkylene glycols include ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, heptanediol, octanediol, nonanediol, decanediol, undecanediol, dodecanediol, etc. Examples of branched alkylene glycols include 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2-methyl-1,8-octanediol, etc. Examples of hydroxyl-containing cyclic hydrocarbons include 1,3-cyclohexanediol, 1,4-cyclohexanediol, and 1,4-cyclohexanediethanol.

[0078] Curing agents with active hydrogen groups are not particularly limited and can use one or more compounds selected from the group consisting of polyol compounds and polyamines.

[0079] In addition to the long-chain polyol compounds mentioned above, various aliphatic polyol compounds and various alicyclic or aromatic polyol compounds can also be used as polyol compounds that can be included in the curing agent.

[0080] Aliphatic polyol compounds are not particularly limited, and examples include: ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,5-hexanediol, 1,6-hexanediol, 2,5-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol. Alcohols, 1,13-tetanediol, 1,14-tetradecanediol, 1,16-hexadecanediol, 1,18-octadecanediol, 1,20-eicosenediol, 2-methyl-1,3-propanediol, neopentyl glycol, 2-butyl-2-ethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, 2-methyl-1,8-octanediol and other alkylene glycol compounds; and glycerol, trimethylolpropane, trimethylolpropane (TMP), pentaerythritol, dimethylolpropionic acid (DHPA), etc.

[0081] Alicyclic polyols are not particularly limited, and examples include 1,4-cyclohexanediethanol and hydrogenated bisphenol A.

[0082] Aromatic polyol compounds are not particularly limited, and examples include: hydroquinone-bis(β-hydroxyethyl) ether, hydroquinone dihydroxyethyl ether (HQEE), resorcinol di(2-hydroxyethyl) ether (HER), 1,3-bis(2-hydroxyethoxybenzene), 1,4-bis(2-hydroxyethoxybenzene), bisphenol A, alkylene oxide adducts of bisphenol A, bisphenol S, alkylene oxide adducts of bisphenol S, etc.

[0083] Polyamines are not specifically limited and can be listed as follows: hydrazine, ethylenediamine, 4,4'-methylenedi(2-chloroaniline) (MOCA), dimethylthiotoluenediamine (DMTDA), diethyltoluenediamine (DETDA), trimethylenediol di(p-aminobenzoate) (TMAB), 4,4'-methylene-bis-(3-chloro-2,6-diethylaniline) (MCDEA), 4,4'-methylene-bis-(2,6-diethylaniline) (MDEA), triisopropanolamine (TIPA), p-bis(aminocyclohexyl)methane (PACM), naphthalene-1,5-diamine, xylenediamine, phenylenediamine, toluene-2,4-diamine, tert-butyltoluenediamine, 1,2-bis(2-aminophenylthioethane), 2-(2-aminoethylamino)ethanol, etc.

[0084] It should be noted that the aforementioned isocyanate compounds, polyols, and / or curing agents can be replaced by one or more hydrophilic groups. That is, the polyurethane resin can have one or more hydrophilic groups. This facilitates self-dispersion in water, thereby easily obtaining a waterborne polyurethane resin. Furthermore, by giving the polyurethane resin hydrophilic groups, the hydrophilicity of the wet paper bearing surface 111 of the wet paper conveyor belt 1 can be improved, and the adhesion of the wet paper can be enhanced. Such hydrophilic groups are not particularly limited and can be listed as: carboxyl, sulfonyl, phosphate, hydroxyl, phenolic hydroxyl, amino, etc. One or more of these hydrophilic groups can be substituted. Additionally, two or more compounds can be substituted by hydrophilic groups; in this case, the substituted hydrophilic groups in these compounds can be the same or different.

[0085] Furthermore, the carboxyl, sulfonyl, phosphate, hydroxyl, phenolic hydroxyl, and amino groups mentioned above can form crosslinking points for reaction with the polycarbodiimide described later, which helps to improve the roughness retention rate and the water resistance and durability of the first resin layer 11. Therefore, the isocyanate compound, polyol, and / or curing agent preferably include one or more groups selected from the group consisting of carboxyl, sulfonyl, phosphate, hydroxyl, phenolic hydroxyl, and amino groups.

[0086] A crosslinking agent crosslinks the polyurethane polymers in the polyurethane resin with each other, thereby improving the water resistance and durability of the first resin layer 11. In this embodiment, the crosslinking agent comprises polycarbodiimide. By utilizing polycarbodiimide to crosslink the polymers in the resin 113 with each other, the water resistance and durability of the wet paper bearing surface 111 can be improved, and the roughness retention rate of the aforementioned wet paper bearing surface 111 can be easily achieved.

[0087] Polycarbodiimide contains multiple carbodiimide bonds, which react with functional groups such as hydroxyl and carboxyl groups to bond with surrounding resins. Polycarbodiimide only needs to contain multiple carbodiimide bonds, and examples include compounds with the structure represented by the following formula (1).

[0088] Chemical Formula 1

[0089]

[0090] In the above formula (1), R 1 Each occurrence is an independent substituted or unsubstituted divalent hydrocarbon group with 1 or more carbon atoms and less than 20 carbon atoms, and n is a number with a number average of 2.0 or more.

[0091] The polycarbodiimide represented by formula (1) above has multiple carbodiimide bonds, which can react with the functional groups of the surrounding resin polymer. The polycarbodiimide having the structure of formula (1) reacts with, for example, hydroxyl groups contained in the resin polymer to form isourea bonds, and the resin polymer and the polycarbodiimide are bonded via isourea bonds. Furthermore, the polycarbodiimide having the structure of formula (1) reacts with, for example, carboxyl groups contained in the resin polymer to form N-acylurea bonds, and the resin polymer and the polycarbodiimide are bonded via N-acylurea bonds. Therefore, when using the polycarbodiimide represented by formula (1), the resin 113 of the first resin layer 11 can be firmly cross-linked, thereby significantly improving water resistance and durability. In addition, the roughness retention rate of the wet paper bearing surface 111 can also be significantly improved.

[0092] In the above equation (1), specifically, R 1 It can be a straight-chain, branched, or cyclic substituted or unsubstituted alkylene or substituted or unsubstituted arylene, or a combination of two or more of these groups.

[0093] Examples of linear alkylene compounds include: methylene, ethylene, n-propylene, n-butylene, n-pentylene, n-hexylene, n-heptylene, n-octylene, n-decylene, n-undecylene, n-dodecylene, n-tridecylene, n-tetradecylene, n-pentadecanylene, n-hexadecylene, n-heptadecylene, n-octadecylene, n-nonadecanylene, and n-eicosylene. Examples of branched alkylene groups include: 1-methylpropylidene, 2-methylpropylidene, 1,1-dimethylpropylidene, 1,2-dimethylpropylidene, 1,3-dimethylpropylidene, 2,2-dimethylpropylidene, 1,2,3-trimethylpropylidene, 1,1,2-trimethylpropylidene, 1,2,2-trimethylpropylidene, 1,1,3-trimethylpropylidene, 1-methylbutylidene, 2-methylbutylidene, 1,1-dimethylbutylidene, and 1,2-dimethylbutylidene. The alkylene group includes, but is not particularly limited to, groups having an alicyclic form such as cyclopentane, cyclohexane, cycloheptane, or cyclooctane rings. R 1 It can bond directly or via an alkylene group having 1 to 3 carbon atoms substituted with an alicyclic group to the oxygen atom adjacent to the alicyclic group. Examples of such cyclic alkylene groups include, for example, 1,4-cyclohexanedimethylbis(methylene). Examples of aryl groups include: monocyclic aromatic groups such as phenylene, condensed polycyclic aromatic groups such as naphthylene, and non-condensed polycyclic aromatic groups such as biphenylene.

[0094] It should be noted that the compound having the structure represented by formula (1) as described above can be obtained by polymerizing a polyisocyanate compound. Therefore, R 1 This can be the residue remaining after removing the isocyanate group from a polyisocyanate compound. In such a case, R 1 For example, residues of the aforementioned polyisocyanate compounds, specifically, residues obtained by removing the isocyanate group from 2,4-toluene diisocyanate (2,4-TDI), 2,6-toluene diisocyanate (2,6-TDI), 4,4'-methylene bis(phenyl isocyanate) (MDI), 1,6-hexamethylene diisocyanate (HDI), dicyclohexylmethane-4,4'-diisocyanate (H12MDI), isophorone diisocyanate (IPDI), tetramethyl-methylene diisocyanate (TMXDI), triisopropylidene phenyl diisocyanate, etc. Specifically, as such R... 1Examples include: 1-methylbenzene-2,4-diyl, 1-methylbenzene-2,6-diyl, diphenylmethane-4,4'-diyl, 1,6-hexene, dicyclohexylmethane-4,4'-diyl, 3,5,5-trimethyl-3-methylenecyclohexane-1-yl, benzene-1,3-dimethylene, triisopropylphenyl-diyl, etc.

[0095] R 1 The substituents are not particularly limited, and examples include: straight-chain or branched alkyl groups having 1 to 10 carbon atoms, straight-chain or branched hydroxyalkyl groups, aromatic groups, and hydrophilic groups described later. Examples of straight-chain alkyl groups include: methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, and n-nonyl. Examples of branched alkyl groups include: isopropyl, tert-butyl, and isobutyl. Examples of hydroxyalkyl groups include: groups formed by substituting one or more hydrogen atoms of the above-mentioned straight-chain or branched alkyl groups with a hydroxyl group. Examples of aromatic groups include: phenyl.

[0096] In addition, in the formula, n can be a number with a mean of 2.0 or higher, for example, a mean of 2.0 or higher and 20.0 or lower, preferably 3.0 or higher and 15.0 or lower.

[0097] Furthermore, the terminal structure of the polycarbodiimide compound having the structure represented by formula (1) above is not particularly limited. For example, in the case of manufacturing by polymerization of a polyisocyanate compound, the terminal structure can be a residue (-R) of the polyisocyanate compound. 1 -N=C=O or -N=C=O), or urethane groups, urea groups, amide groups, etc. derived from these.

[0098] Furthermore, the polycarbodiimide compound represented by formula (1) can have a hydrophilic group. Such a hydrophilic group is not particularly limited and can be listed as: carboxyl, sulfonyl, phosphate, hydroxyl, phenolic hydroxyl, amino, etc. It can be substituted by one or more of these hydrophilic groups. Alternatively, it can be the aforementioned R... 1 A portion of it is replaced by a hydrophilic group, or a portion of the terminal structure is replaced by a hydrophilic group.

[0099] Alternatively, the polycarbodiimide compound can have a hydrophobic group. It can be the aforementioned R... 1 A portion of it is replaced by a hydrophobic group, or a portion of the terminal structure is replaced by a hydrophobic group.

[0100] It should be noted that although the above description focuses on linear polycarbodiimide compounds, the polycarbodiimide compounds that can be used in this embodiment are not limited to this, and branched polycarbodiimide compounds may also be used.

[0101] Furthermore, the amount of polycarbodiimide used relative to resin 113 is not particularly limited, but is, for example, 0.3 parts by mass or more and 90 parts by mass or less relative to 100 parts by mass of resin, preferably 0.6 parts by mass or more and 80 parts by mass or less, and more preferably 1.0 parts by mass or more and 30 parts by mass or less.

[0102] Furthermore, the crosslinking agent may further include melamine-based, epoxy-based, isocyanate-based, and other crosslinking agents. Moreover, the crosslinking agent can be a crosslinking agent composition containing solvents, dispersants, surfactants, etc., or it can be a liquid (e.g., solution, dispersion, emulsion).

[0103] In addition, when the crosslinking agent is in solution form, the crosslinking agent is an aqueous solution.

[0104] The aforementioned crosslinking agent can be used after being mixed with materials used to form polyurethane resins, such as urethane prepolymers and curing agents, or after being mixed with a dispersion of aqueous polyurethane resin. Alternatively, it can be used by coating a solution of the crosslinking agent onto the wet paper carrier surface 111 after the first resin layer 11 is formed and allowing it to react.

[0105] In addition, the resin 113 constituting the first resin layer 11 may also contain one or more inorganic fillers such as titanium oxide, kaolin, clay, talc, diatomaceous earth, calcium carbonate, calcium silicate, magnesium silicate, silicon dioxide, and mica.

[0106] It should be noted that the composition and type of resin material and inorganic filler in the first resin layer 11 may be different or the same in different parts of the first resin layer 11.

[0107] Furthermore, the first resin layer 11 preferably has water-impermeable properties. That is, the first resin layer 11 is preferably water-impermeable.

[0108] The fiber-reinforced substrate layer 13 is composed of a fiber-reinforced substrate 131 and a resin 133.

[0109] The resin 133 exists in the fiber-reinforced substrate layer 13 in such a way that it fills the gaps between the fibers in the fiber-reinforced substrate 131. That is, a portion of the resin 133 is impregnated in the fiber-reinforced substrate 131, while the fiber-reinforced substrate 131 is embedded in the resin 133.

[0110] The fiber-reinforced substrate 131 is not particularly limited; for example, it can be a textile typically woven using warp and weft yarns on a loom. Alternatively, a checkered material formed by overlapping warp and weft rows without weaving can also be used.

[0111] The fineness of the fibers constituting the fiber-reinforced substrate 131 is not particularly limited, and can be, for example, 300 to 10000 dtex, preferably 500 to 6000 dtex.

[0112] Furthermore, the fineness of the fibers constituting the fiber-reinforced substrate 131 can vary depending on the part where the fiber is used. For example, the fineness of the fibers may differ in the warp and weft threads of the fiber-reinforced substrate 131.

[0113] As the material for fiber-reinforced substrate 131, it can be used alone or in combination with one or more of the following: polyester (polyethylene terephthalate, polybutylene terephthalate, etc.), aliphatic polyamide (polyamide 6, polyamide 11, polyamide 12, polyamide 612, etc.), aromatic polyamide (aramid), polyvinylidene fluoride, polypropylene, polyether ether ketone, polytetrafluoroethylene, polyethylene, wool, cotton, metal, etc.

[0114] The material of resin 133 is not particularly limited. For example, one of various resins that can be used alone for resin 113 in the first resin layer 11 can be used alone, or two or more can be used in combination. The type and composition of resin 133 can be the same as or different from the resin 113 constituting the first resin layer 11.

[0115] It should be noted that the composition and type of resin 133 in the fiber-reinforced substrate layer 13 may be different or the same in different parts of the fiber-reinforced substrate layer 13.

[0116] The second resin layer (roller-side resin layer) 15 is a layer mainly composed of resin 153, which is disposed on one main surface of the fiber-reinforced substrate layer 13.

[0117] The second resin layer 15 forms the roller contact surface 151, which is used to contact the roller (described later) on the main surface opposite to the main surface that bonds to the fiber-reinforced substrate layer 13. When the wet paper conveyor belt 1 is used, the roller contact surface 151 contacts the roller, and the power for conveying the wet paper is obtained from the roller.

[0118] The resin 153 constituting the second resin layer 15 can be one resin material that can be used in the first resin layer 11 as described above, or a combination of two or more resin materials. The type and composition of the resin 153 constituting the second resin layer 15 can be the same as or different from the resin 113 constituting the first resin layer 11 or the resin 133 constituting the fiber-reinforced substrate layer 13.

[0119] In particular, polyurethane resin is preferred as the resin 153 constituting the second resin layer 15 from the viewpoints of mechanical properties, wear resistance, and flexibility.

[0120] In addition, the second resin layer 15 may contain one or more inorganic fillers, just like the first resin layer 11.

[0121] It should be noted that the composition and type of resin material and inorganic filler in the second resin layer 15 may be different or the same in different parts of the second resin layer 15.

[0122] The size of the wet paper conveyor belt 1 described above is not particularly limited and can be appropriately set according to its purpose.

[0123] For example, the width of the wet paper conveyor belt 1 is not particularly limited and can be 700–13500 mm, preferably 2500–12500 mm.

[0124] For example, the length (circumference) of the wet paper conveyor belt 1 is not particularly limited and can be 4 to 35 m, preferably 10 to 30 m.

[0125] In addition, the thickness of the wet paper conveyor belt 1 is not particularly limited, and can be, for example, 1.5 to 7.0 mm, preferably 2.0 to 6.0 mm.

[0126] In addition, the thickness of each part of the wet paper conveyor belt 1 can be different or the same.

[0127] The wet paper conveyor belt 1 described above can be manufactured by, for example, the wet paper conveyor belt manufacturing method described in this embodiment, which will be described later.

[0128] In summary, the wet paper conveyor belt 1 of this embodiment maintains a roughness retention rate of 40% or more on the wet paper bearing surface 111 in a wet state, thereby suppressing changes in the wet paper's adhesion and peelability, and thus enabling long-term stable transmission of wet paper. In other words, the wet paper conveyor belt 1 suppresses changes in the properties of the wet paper bearing surface 111 during use.

[0129] As a variation of the aforementioned wet paper conveyor belt 1, the following scheme can be listed: the wet paper conveyor belt 1 has a layer formed by knitting butt-joint fibers on the wet paper bearing side and / or roller side of the fiber-reinforced substrate 131, and impregnating the aforementioned resin material into the butt-joint fibers. It should be noted that, as the material for the butt-joint fibers, one or more materials that can be used for the fiber-reinforced substrate 131 can be used alone or in combination.

[0130] 2. Manufacturing method of papermaking tape

[0131] Next, an example of a preferred embodiment of the method for manufacturing the papermaking tape of the present invention will be described. Figures 2-5 This is a schematic diagram illustrating an example of a preferred embodiment of the method for manufacturing the papermaking tape of the present invention.

[0132] The method for manufacturing paper tape of the present invention includes a step of forming at least one resin layer.

[0133] In the aforementioned process, the resin near at least the surface of the formed resin layer is crosslinked with polycarbodiimide. Hereinafter, as an example of a paper conveyor belt, the wet paper conveyor belt 1 described above will be used as an example. Therefore, the manufacturing method of the wet paper conveyor belt 1 of this embodiment includes a process of forming an annular laminate 1' (lamination process), the laminate 1' having a second resin layer (roller-side resin layer) 15 as the innermost layer and a first resin layer (wet paper carrier-side resin layer) 11 as the outermost layer. In the lamination process, the resin 113 near at least the wet paper carrier surface 111 of the first resin layer 11 is crosslinked with polycarbodiimide.

[0134] In this lamination process, an annular and strip-shaped laminate 1' is formed, with a second resin layer 15 as the innermost layer and a precursor 11' having a first resin layer as the outermost layer. The laminate 1' can be formed by any method, but in this embodiment, firstly, resin material is applied to the fiber-reinforced substrate 131 such that the resin material of the second resin layer 15 penetrates the fiber-reinforced substrate 131, thereby forming the fiber-reinforced substrate layer 13, and simultaneously forming the second resin layer 15 on the inner side of the fiber-reinforced substrate layer 13. Next, the resin material of the wet paper carrier-side resin layer 11 is applied to the outer surface of the formed fiber-reinforced substrate layer 13, thereby forming the precursor 11' of the wet paper carrier-side resin layer.

[0135] Specifically, such as Figure 2 As shown, the annular and strip-shaped fiber-reinforced substrate 131 is hung in contact with two parallel rollers 21.

[0136] Next, as Figure 3 As shown, resin material for the second resin layer 15 is applied to the outer surface of the fiber-reinforced substrate 131. The resin material can be applied by any method. In this embodiment, the fiber-reinforced substrate 131 is rotated by a roller 21 while resin material is ejected from a resin nozzle 25, thereby applying resin material to the fiber-reinforced substrate 131. Additionally, the applied resin material is simultaneously and uniformly coated onto the fiber-reinforced substrate 131 using a coating rod 23. At this time, the coated resin material can penetrate the fiber-reinforced substrate 131. Therefore, in this embodiment, not only can the resin 133 contained in the fiber-reinforced substrate 131 be formed, but also the resin 153 constituting the second resin layer 15 can be formed, thereby simultaneously forming the fiber-reinforced substrate layer 13 and the second resin layer 15.

[0137] Next, as Figure 4As shown, the resin material of the first resin layer 11 is applied to the outer surface of the formed fiber-reinforced substrate layer 13. The resin material can be applied by any method. In this embodiment, the formed fiber-reinforced substrate layer 13 and the second resin layer 15 are rotated by a roller 21, while the resin material is ejected from the resin nozzle 25, thereby applying the resin material to the outer surface of the fiber-reinforced substrate layer 13. Additionally, the applied resin material is simultaneously coated uniformly using a coating rod 23. It should be noted that the resin material constituting each layer can be prepared as a mixture with the aforementioned inorganic filler before application.

[0138] It should be noted that, as described above, in this embodiment, in this process, the resin 113 near at least the wet paper bearing surface 111 of the first resin layer 11 is crosslinked with polycarbodiimide. When the resin 113 is crosslinked with polycarbodiimide, for example, if the resin material (resin composition) used to form the first resin layer 11 contains a crosslinking agent comprising polycarbodiimide, crosslinking is performed simultaneously with the drying process described later. This operation is simple and reliable, and is therefore preferred. For example, if the resin composition used to form the first resin layer 11 contains an aqueous polyurethane resin, a crosslinking agent is mixed into an aqueous dispersion of the aqueous polyurethane resin. Then, as... Figure 4 As shown, the resin material of the first resin layer 11 is applied to the outer surface of the fiber-reinforced substrate layer 13.

[0139] Alternatively, a crosslinking agent may be applied to the precursor 11' of the formed first resin layer, and crosslinked by drying as described later. This method can be used, for example, when it is difficult to mix the crosslinking agent into the resin material used to form the first resin layer 11.

[0140] Next, the coated resin material is dried and crosslinked. This yields a laminate 1' consisting of a first resin layer precursor 11', a fiber-reinforced substrate layer 13, and a second resin layer 15, sequentially stacked from the outer surface. The method for drying and crosslinking the resin material is not particularly limited; for example, it can be carried out by heating or ultraviolet irradiation.

[0141] In addition, when drying and cross-linking resin materials by heating, methods such as far-infrared heaters and hot air can be used.

[0142] Furthermore, when drying and crosslinking the resin material by heating, the heating temperature of the resin material is preferably 60–150°C, more preferably 90–140°C. The heating time is, for example, 0.5–30 hours, preferably 1–25 hours.

[0143] Next, the surface roughness of the outer surface of the precursor 11' of the wet paper carrier side resin layer is adjusted to form a wet paper carrier side resin layer 11 having a wet paper carrier surface 111 (roughness adjustment process). As a result, a wet paper conveyor belt 1, which has a wet paper carrier surface 111 formed thereon and serves as a papermaking belt, is obtained.

[0144] The surface roughness of the outer surface can be adjusted by, for example, grinding and / or polishing. Specifically, such as Figure 3 As shown, the grinding device 27 or polishing device (not shown) is brought into contact with the laminate 1', which is suspended on the two rollers 21, and adjustment is performed thereby. This allows the desired arithmetic mean roughness of the wet paper bearing surface 111 to be obtained.

[0145] It should be noted that if the wet paper bearing surface 111 of the wet paper conveyor belt 1 has reached the required state before grinding or polishing, grinding and / or polishing can be omitted.

[0146] It should be noted that in the above-described method for manufacturing paper tape, the roll-side resin material penetrates the fiber-reinforced substrate 131 from its outer surface, forming a second resin layer 15 on its inner surface (through-through method). However, it is also possible to apply the resin material constituting the second resin layer 15 to the outer surface of the fiber-reinforced substrate 131, forming the fiber-reinforced substrate layer 13 and the second resin layer 15 stacked on its outer surface, then reversing them inside out, and coating the outer surface of the fiber-reinforced substrate layer 13 (which was the inner surface before reversal) with the resin material of the first resin layer 11, thereby forming the precursor 11' of the first resin layer (reversal method).

[0147] Furthermore, as a variation of the above-described paper conveyor belt manufacturing method, a method is proposed whereby a fiber-reinforced substrate obtained by knitting butt-joint fibers on the wet paper bearing side and / or roll side of the fiber-reinforced substrate is used instead of the aforementioned fiber-reinforced substrate 131. This results in a wet paper conveyor belt (paper conveyor belt) having a first resin layer and / or a second resin layer impregnated with resin material in the aforementioned butt-joint fiber layer.

[0148] 3. Paper making machine

[0149] Next, an example of a paper machine to which the papermaking belt of the present invention is applied will be described. Figure 6 This is a schematic diagram illustrating an example of a papermaking machine to which the papermaking belt of the present invention is applicable. Figure 6The paper machine shown includes a wire section 30, a press section 40, and a drying section 50. Furthermore, in the figure, the wet paper W, indicated by the dashed lines, is sequentially conveyed from the wire section 30 to the press section 40 and then to the drying section 50, undergoing dewatering, pressing, and drying during the conveying process to form paper. Additionally, the paper machine described below is a so-called closed-loop traction paper machine. Therefore, when the wet paper W is conveyed in the press section 40, it is carried on any one of the press felts 41, 42, 43, or the wet paper conveyor belt 1; there is no section where the wet paper W travels independently.

[0150] The wire section 30 holds the pulp slurry on the wire 31 and dewaters it to form a sheet-like wet paper W. The wire section 30 is a known structure, and the description of its main parts is omitted. The wet paper W, after being dewatered by the wire section 30, is conveyed by the wire 31 supported by the guide roller 33 and then transferred to the press felt 41 of the press section 40.

[0151] The pressing section 40 consists of a roller pressing section 40A and a shoe pressing section 40B. The roller pressing section 40A mainly comprises pressing felts 41 and 42, pressing rollers 44A and 44B, suction rollers 45A and 45B, and guide rollers 48.

[0152] The press felts 41 and 42 are annular strips that carry and transport the wet paper W. The press felts 41 and 42 are configured to be supported by a plurality of guide rollers 48 and suction rollers 45A and 45B between press rollers 44A and 44B. The suction roller 45A is configured to bring the press felt 41, supported on the front side in the transport direction (flow direction) of the wet paper W, into contact with the wire 31. The wet paper W is drawn in by the suction roller 45A, thereby transferring the wet paper W from the wire 31 to the press felt 41.

[0153] Press rolls 44A and 44B constitute a roll press mechanism 44, which, together with press felts 41 and 42, press the wet paper W to remove water from the wet paper W. Suction roll 45B is configured to support the press felt 42 on the inner side in the conveying direction (flow direction) of the wet paper W, suck up the wet paper W carried on the press felts 41 and 42, peel it off from the press felt 41, and simultaneously ensure that it is carried only on the press felt 42.

[0154] The shoe press section 40B mainly comprises a wet paper conveyor belt 1, a press felt 43, a shoe press mechanism 46, suction rollers 47, and guide rollers 48. The wet paper conveyor belt 1 is as described above. The press felt 43 is an annular belt that carries and conveys the wet paper W. The wet paper conveyor belt 1 and the press felt 43 are configured to be supported by multiple guide rollers 48 and suction rollers 47 via the shoe press mechanism 46.

[0155] The suction roller 47 is configured to abut the supported press felt 43 against the press felt 42 on the front side of the wet paper W in the conveying direction (flow direction). Furthermore, the suction roller 47 draws in the wet paper W and transfers it from the press felt 42 to the press felt 43.

[0156] The boot press mechanism 46 includes a press roll 46A, a boot 46B, and a boot press belt 46C. The boot 46B has a recess corresponding to the shape of the press roll 46A, and together with the press roll 46A, it presses the wet paper W carried on the wet paper conveyor belt 1 and the press felt 43 via the boot press belt 46C. The wet paper W carried on the press felt 43 and fed into the boot press mechanism 46 is carried on the wet paper conveyor belt 1 after passing through the boot press mechanism 46.

[0157] The wet paper W is dried in the drying section 50. The drying section 50 has a known configuration, and the description of its main parts is omitted. The drying cloth 53 of the drying section 50 is supported by the suction roller 51 and abuts against the wet paper conveyor belt 1. The wet paper W is picked up by the suction roller 51 and transferred from the wet paper conveyor belt 1 to the drying cloth 53.

[0158] Here, the movement of the wet paper W in the aforementioned paper machine will be explained. It should be noted that, of course, since the wet paper W is a continuous structure, the movement of a portion of the wet paper W will be explained.

[0159] First, the wet paper W passes sequentially through the wire 31 of the wire section 30, the press felt 41 of the press section 40, and the roller press mechanism 44, and is transferred from the press felt 42 to the press felt 43. Next, it is conveyed through the press felt 43 to the shoe press mechanism 46. In the shoe press mechanism 46, the wet paper W is held between the press felt 43 and the wet paper conveyor belt 1 and is pressurized by the shoe 46B and the press roller 46A, wherein the shoe 46B is pressurized via the shoe press belt 46C.

[0160] At this point, the press felt 43 has high water permeability, while the wet paper conveyor belt 1 has very low water permeability. Therefore, in the boot press mechanism 46, moisture from the wet paper W is transferred to the press felt 43.

[0161] After disengaging from the boot press mechanism 46, the pressure is released rapidly, causing the press felt 43, wet paper W, and wet paper conveyor belt 1 to expand in volume. This expansion, along with the capillary action of the pulp fibers constituting the wet paper W, causes some of the moisture in the press felt 43 to transfer to the wet paper W, resulting in a phenomenon known as rewetting.

[0162] However, in summary, due to the very low permeability of the wet paper conveyor belt 1, it does not retain moisture inside. Therefore, rewetting from the wet paper conveyor belt 1 is almost nonexistent, and the wet paper conveyor belt 1 helps improve the dewatering efficiency of the wet paper. It should be noted that the wet paper W, after exiting the shoe press mechanism 46, is conveyed by the wet paper conveyor belt 1. Then, the wet paper W is adsorbed by the suction roller 51 and sent to the drying section 50 by the drying cloth 53.

[0163] Here, as a wet paper conveyor belt 1, the wet paper bearing surface (outer peripheral surface) of the resin layer on its wet paper bearing side is required to have the following functions: conveying the wet paper W in a state where it is adhered after disengaging from the boot-type press mechanism 46 (wet paper adhesion); and smoothly peeling off the wet paper when conveying the wet paper W to the next section (wet paper peelability). In this way, the wet paper conveyor belt 1 is required to have the opposite functions, and the adhesion of the wet paper bearing surface 111 of the wet paper conveyor belt 1 to the wet paper W needs to be strictly controlled.

[0164] On the other hand, the wet paper conveyor belt 1 deteriorates due to friction and the pressing pressure in the shoe press mechanism 46 during long-term continuous travel. Furthermore, contaminants contained in the wet paper W, such as sizing agents, fillers, and their reactants, adhere to and accumulate on the outer surfaces of the wet paper conveyor belt 1, including the wet paper bearing surface 111. As a result, it is difficult for the wet paper conveyor belt 1 to maintain the properties of its wet paper bearing surface 111 during long-term continuous travel. However, the wet paper conveyor belt 1 according to this embodiment suppresses changes in properties and changes in wet paper adhesion and wet paper peelability by maintaining the roughness retention rate of the wet paper bearing surface 111 above a specified level.

[0165] The present invention has been described in detail above based on preferred embodiments, but the present invention is not limited thereto. Each component can be replaced with any component that can perform the same function, or any component can be added.

[0166] Furthermore, in the above description, a paper conveyor belt was used as an example of a papermaking belt, but the present invention is not limited thereto. For example, the papermaking belt of the present invention can also be a boot press belt, or other papermaking belts.

[0167] Furthermore, in the above description, the wet paper bearing surface 111 of the wet paper conveyor belt 1 was described as a surface cross-linked by polycarbodiimide. However, the papermaking belt of the present invention is not limited to this. As long as the specified roughness retention rate is achieved, cross-linking by polycarbodiimide may not be required.

[0168] Example

[0169] The present invention will be described in more detail below through embodiments, but the present invention is not limited to these embodiments.

[0170] 1. Manufacturing of wet paper conveyor belts

[0171] First, wet paper conveyor belts of Examples 1 to 6 and Comparative Examples 1 and 2 were manufactured according to the following configuration.

[0172] Fiber-reinforced substrates

[0173] The fiber-reinforced substrate of the wet paper conveyor belts in Examples 1-6 and Comparative Examples 1 and 2 uses the following substances.

[0174] Top warp: 2000 dtex twisted monofilament composed of polyamide 6

[0175] Bottom warp: 2000 dtex twisted monofilament composed of polyamide 6

[0176] Weft yarn: 1400 dtex twisted monofilament composed of polyamide 6

[0177] Fabric: 40 warp threads per 5cm, 40 weft threads per 5cm, double weft fabric.

[0178] Formation of stacked bodies

[0179] Fiber-reinforced substrates are hung on two rollers. Next, resin material constituting the roller-side resin layer is applied, impregnated, and layered onto the outer surface of each fiber-reinforced substrate, forming a fiber-reinforced substrate layer and a roller-side resin layer. Then, resin material for the wet paper carrier-side resin layer is applied to the outer surface of each fiber-reinforced substrate layer, and the wet paper carrier-side resin layer is layered. A laminate is formed, consisting of a wet paper carrier-side resin layer, a fiber-reinforced substrate layer, and a roller-side resin layer, starting from the outermost layer. The laminate is heated and dried to obtain a semi-finished wet paper conveyor belt.

[0180] It should be noted that the resin materials used to form each layer of Examples 1 to 6 and Comparative Examples 1 and 2 were the substances shown in Tables 1 and 2, respectively.

[0181] In the table, "PU1" represents a polyurethane aqueous dispersion ("ETERNACOLL (registered trademark) UW-1005D-C1", manufactured by Ube Industries, Ltd.); "PU2" represents a polyurethane aqueous dispersion ("ETERNACOLL (registered trademark) UW-1005E", manufactured by Ube Industries, Ltd.); "PU3" represents a polyurethane aqueous dispersion ("ETERNACOLLUW-1005A", manufactured by Ube Industries, Ltd.); and "PU4" represents a polyurethane aqueous dispersion ("Bayhydrol (registered trademark) 124", manufactured by COVESTRO). All of these are polyurethane resins manufactured using aliphatic polyisocyanate compounds and polycarbonate diols. Additionally, in the table, "CI1" represents an aqueous solution of polycarbodiimide ("CARBODILITE V-02-L2", manufactured by Nisshinbo Chemical Co., Ltd.); "CI2" represents an aqueous solution of polycarbodiimide ("CARBODILITE SV-02", manufactured by Nisshinbo Chemical Co., Ltd.); and "MF" represents melamine-formaldehyde resin ("Resimene (registered trademark) 747", manufactured by INEOSMELAMES LLC.

[0182] In addition, the contents of each material in the table record only the solid content of the target compound. For example, in the case of a polyurethane aqueous dispersion, the amount of water and additives in the aqueous dispersion is not considered; only the solid content of the polyurethane resin is recorded. The balance of the resin material is primarily water, but this balance also includes leveling agents, defoamers, pH adjusters, tackifiers, and organic solvents from each material.

[0183] Grinding and polishing

[0184] Using sandpaper of grit #80 to #600 appropriately mounted on a grinding device, the wet paper bearing surface of the wet paper conveyor belts (semi-finished products) of Examples 1 to 6 and Comparative Examples 1 and 2 was ground. Additionally, appropriate polishing was applied to adjust the surface roughness of the wet paper contact surface, so that the arithmetic mean roughness of the wet paper bearing surface of the wet paper conveyor belts in each example was 0.3 to 20 μm. Thus, the wet paper conveyor belt was completed.

[0185] It should be noted that the dimensions are 20.5m in length and 900mm in width.

[0186] 2. Evaluation of wet paper conveyor belts

[0187] 2.1. Roughness retention rate, surface roughness

[0188] The roughness retention rate of the wet paper carrier surface of the wet paper conveyor belts of Examples 1-6 and Comparative Examples 1 and 2 was measured. The roughness retention rate was evaluated as follows.

[0189] First, the surface roughness (arithmetic mean roughness) of the wet paper carrier surface of the wet paper conveyor belt before the contact treatment (described later) was measured. The surface roughness of the wet paper carrier surface of the wet paper conveyor belt before the contact treatment was measured under wet conditions. Specifically, first, a sample of the wet paper conveyor belt (a circular disc with a diameter of 80 mm) was immersed in a constant temperature water bath at 70°C for 20 hours. Next, the surface roughness of the wet paper carrier surface under wet conditions was measured. It should be noted that, as the surface roughness of the wet paper carrier surface under wet conditions, the surface roughness was measured at any 5 points, and the average value was taken.

[0190] Testing machine: SURFCOM480A (Tokyo Seimitsu Corporation)

[0191] Measurement conditions: Scanning speed 0.6 m / s

[0192] Test length 8.0 mm

[0193] Cutoff value 2.5mm

[0194] Next, the sample from the wet paper conveyor belt is subjected to contact treatment. Using... Figure 7 The device shown is used for contact processing. For example... Figure 7As shown, a stainless steel gasket 63 is placed between the press pans 61 and 62, and warm water 66 at 70±5°C is poured into the metal gasket 63 to maintain the temperature. Next, the sample of wet paper conveyor belt 1 is arranged such that the wet paper bearing surface 111 abuts against the bottom surface of the metal container 63, and is pressed by the press pans 61 from above, separated by a stainless steel plate 64 and eight sheets of newspaper 65. The pressing conditions are as follows.

[0195] Pressing pressure: 100±3Kg / cm 2

[0196] Pressing time: 20 hours

[0197] Pressing temperature: 70±5℃

[0198] Surface roughness of the bottom surface of metal container 63: 0.05 μm

[0199] Next, the surface roughness of the wet paper bearing surface of the wet paper conveyor belt after the contact treatment was measured in the same manner as the sample before the contact treatment. The results are shown in Tables 1 and 2.

[0200] 2.2 Evaluation of Wet Paper Transportability

[0201] The wet paper conveyor belts of Example 1 and Comparative Example 2 were run for an extended period of time to evaluate changes in wet paper conveyability.

[0202] use Figure 8 The evaluation device for the wet paper conveyor belt shown evaluates the adhesion and peelability of the wet paper conveyor belt to the wet paper W under the following conditions, by passing the wet paper W through the press zone 12. It should be noted that... Figure 8 The evaluation apparatus shown includes a pressing section 40' with a boot-type pressing section 40B' and a drying section 50'. Furthermore, the pressing section 40' and the drying section... Figure 6 The structure of the press section 40 shown is basically the same after omitting the roller press section 40A. Furthermore, the pressing conditions, the structure of the press felt 43, and the structure of the wet paper are described below. Additionally, the wet paper conveyor belt 1” is the wet paper conveyor belt involved in Example 1 or Comparative Example 2.

[0203] Pressing conditions

[0204] Copying speed: 1200m / min

[0205] Pressing pressure: 1050kN / m

[0206] Composition of press felt 43

[0207] Double-sided knitted butt-joint fibers are used to form a middle butt-joint fiber layer (outer periphery) and a back butt-joint fiber layer (inner periphery). Butt-joint fibers are then knitted on the outer periphery of the middle butt-joint fiber layer to form a surface butt-joint fiber layer, which is used as press felt 43. It should be noted that the composition of the base fabric and the formation conditions of each butt-joint fiber layer are described below. Furthermore, as press felt 43, three types of felts with different fineness of the surface butt-joint fibers are prepared. The fineness of the surface butt-joint fibers of each press felt is 3.3 dtex, 6.6 dtex, or 11 dtex.

[0208] Base fabric: Pressed base fabric

[0209] Upper fabric base fabric

[0210] Warp: 1400 dtex monofilament made of nylon 6

[0211] Weft yarn: 500 dtex monofilament composed of nylon 6

[0212] Weave: 50 warp threads / 5cm, 40 weft threads / 5cm, 1 / 1 plain weave

[0213] Base fabric

[0214] Warp: 2000 dtex twisted monofilaments made of nylon 6

[0215] Weft yarn: 1400dtex twisted monofilament composed of nylon 6

[0216] Tissue: 40 warp threads / 5cm, 40 weft threads / 5cm, 3 / 1 collapsed tissue

[0217] Knitted on the base fabric with butt fibers

[0218] Surface bonding fiber: 200g / m² bonding fiber composed of nylon 6 2

[0219] Middle layer butt-joint fiber: 20dtex butt-joint fiber composed of nylon 6, 300g / m 2

[0220] Backing fiber: 20dtex nylon 6 backing fiber, 100g / m² 2

[0221] It should be noted that during the evaluation, a shower head and a water tank (not shown in the figure) were used, and the water content of the felt 43 was set as follows.

[0222] Felt moisture content: Felt moisture weight / (felt moisture weight + felt weight) = 30% adjustment

[0223] Wet paper (handwritten sheet material)

[0224] Pulp: LBKP 100% CSF 450mL

[0225] Weight: 60g / m 2

[0226] Moisture content of wet paper before pressing: Weight of wet paper before pressing / (Weight of wet paper before pressing + Absolute dry weight of wet paper)

[0227] =60% adjustment (clamping the filter paper for moisture adjustment)

[0228] Wet paper size: 200mm (length) x 200mm (width)

[0229] Fit determination

[0230] Under the above conditions, the sealing performance of the wet paper conveyor belt 1” is evaluated based on whether the wet paper W is tightly sealed to the wet paper conveyor belt 1” after passing through the pressing zone of the boot-type press mechanism 46. It should be noted that when evaluating the sealing performance of the wet paper conveyor belt 1”, press felts 43 with different fineness of surface-jointed fibers are used, and the evaluation is conducted according to the following standards. Furthermore, the evaluation of the sealing performance of the wet paper conveyor belt 1” is performed immediately after it is attached and again after running the evaluation device for 7 days while replenishing water.

[0231] Peelability determination

[0232] When evaluating the peelability of the wet paper conveyor belt 1", the judgment is made based on whether the wet paper W carried on the wet paper conveyor belt 1” is transferred to the drying cloth 53. It should be noted that during the evaluation, the vacuum degree of the suction roller 51 is changed to -20kPa, -30kPa, and -40kPa. Under each vacuum degree, it is confirmed whether the wet paper W is transferred to the drying cloth 53, and the evaluation is carried out according to the following standards. In addition, the peelability evaluation of the wet paper conveyor belt 1” is carried out immediately after the wet paper conveyor belt 1” is attached and after 7 days of running the evaluation device while adding water.

[0233] evaluate

[0234] A: Regardless of the fineness of the surface-joined fibers of the press felt 43, the wet paper W is always in close contact with the wet paper conveyor belt 1'. In addition, regardless of the vacuum level of the suction roller 51, the wet paper W is always transferred to the drying cloth 53.

[0235] B: When the fineness of the surface-joined fibers of the press felt 43 is 6.6 dtex or 11 dtex, the wet paper W is tightly bonded to the wet paper conveyor belt 1”. However, when the fineness of the surface-joined fibers is 3.3 dtex, the wet paper W is not tightly bonded to the wet paper conveyor belt 1”. In addition, when the vacuum degree of the suction roller 51 is -30 kPa or -40 kPa, the wet paper W is transferred to the drying fabric 53. However, when the vacuum degree of the suction roller 51 is -20 kPa, the wet paper W is not transferred to the drying fabric 53.

[0236] C: When the fineness of the surface-joined fibers of the press felt 43 is 11 dtex, the wet paper W is in close contact with the wet paper conveyor belt 1'. However, when the fineness of the surface-joined fibers is 3.3 dtex or 6.6 dtex, the wet paper W is not in close contact with the wet paper conveyor belt 1'. In addition, when the vacuum degree of the suction roller 51 is -40 kPa, the wet paper W is transferred to the drying cloth 53. However, when the vacuum degree of the suction roller 51 is -20 kPa or -30 kPa, the wet paper W is not transferred to the drying cloth 53.

[0237] D: Regardless of the fineness of the surface-joined fibers of the press felt 43, the wet paper W does not fit tightly with the wet paper conveyor belt 1”.

[0238] It should be noted that in the above evaluation, if the result is A to B, the wet paper conveying performance is considered to be good. Furthermore, when evaluating after 7 days of operation, the less the above evaluation result decreases, the less the decrease in wet paper conveying performance is considered. If the result is A to B, the wet paper conveying performance of the 1” wet paper conveyor belt is considered to be stable over long-term use.

[0239] Table 1

[0240]

[0241]

[0242] Table 2

[0243]

[0244] As shown in Table 1, the wet paper conveyor belts of Examples 1-6 exhibit a wet paper bearing surface roughness retention rate of over 40%, suppressing changes in the properties of the wet paper bearing surface and enabling long-term stable use. In contrast, the wet paper conveyor belts of Comparative Example 1 (which did not use a crosslinking agent) and Comparative Example 2 (which used melamine-formaldehyde resin as a crosslinking agent) exhibited a wet paper bearing surface roughness retention rate of less than 40%, failing to suppress changes in the properties of the wet paper bearing surface and thus not enabling long-term stable use.

[0245] In fact, after evaluating the wet paper conveying performance of the wet paper conveyor belts of Example 1 and Comparative Example 2, the wet paper conveyor belt involved in Example 1 maintained good wet paper conveying performance even after 7 days of continuous operation, without any decrease. In contrast, the wet paper conveyor belt involved in Comparative Example 2 showed decreased wet paper conveying performance after 7 days of continuous operation, making it difficult to use for a long period of time.

Claims

1. A papermaking belt for a paper machine, having at least one resin layer comprising resin, The resin comprises an aqueous polyurethane resin; In a warm water bath at 70±5℃, at a concentration of 100±3Kg / cm 2 Under pressure, the surface of the resin layer is pressed against a metal plate with a surface roughness of less than 0.10 μm for 20 hours. The arithmetic mean roughness of the surface of the resin layer after pressing is more than 40% higher than the arithmetic mean roughness of the surface of the resin layer before pressing.

2. The papermaking belt according to claim 1, wherein, The resin near at least the surface of the resin layer is crosslinked by a polycarbodiimide having the structure shown in formula (1); In the above formula (1), R 1 Each occurrence is an independent divalent hydrocarbon group with 1 or more carbon atoms and less than 20, either substituted or unsubstituted, and n is a number with a number average of 2.0 or more.

3. The papermaking belt according to any one of claims 1 to 2, wherein, The arithmetic mean surface roughness of the resin layer in a wet state is greater than 0.3 μm and less than 20 μm.

4. The papermaking belt according to any one of claims 1 to 2, wherein, The resin near at least the surface of the resin layer contains N-acylurea bonds and / or isourea bonds.

5. The papermaking belt according to any one of claims 1 to 2, wherein, The surface of the resin layer includes a wet paper contact surface.

6. The papermaking belt according to any one of claims 1 to 2, wherein, The papermaking belt is a wet paper conveyor belt.

7. The papermaking belt according to any one of claims 1 to 2, wherein, The papermaking belt is a boot-type press belt.

8. A method for manufacturing papermaking tape according to any one of claims 1-7, comprising a step of forming at least one resin layer. The resin comprises an aqueous polyurethane resin; In the process, the resin near at least the surface of the formed resin layer is crosslinked by a polycarbodiimide having the structure shown in formula (1); In the above formula (1), R 1 Each occurrence is an independent divalent hydrocarbon group with 1 or more carbon atoms and less than 20, either substituted or unsubstituted, and n is a number with a number average of 2.0 or more.

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