Papermaking belt and method for manufacturing papermaking belt

Abstract

Provided is a papermaking belt in which resin peeling of a resin layer is inhibited during use, and a method for manufacturing the papermaking belt. The papermaking belt according to an embodiment of the present invention is a papermaking belt for a papermaking machine, and the papermaking belt is provided with at least one resin layer containing resin, and the total number of protrusions having a height of 50 μm or more and cracks having a length of 10 mm or more on at least one surface of the resin layer is 1.0 per m 2 Furthermore, the papermaking belt according to another aspect of the present invention is a papermaking belt for a papermaking machine, and the papermaking belt is provided with at least one resin layer containing resin, and the resin layer is formed using a resin composition containing an aqueous dispersion of urethane resin, the resin composition containing an organic solvent having a boiling point of 100°C or more at 1 atm.

Description

TECHNICAL FIELD

[0001] The present application relates to a papermaking belt and a method for manufacturing 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 the purpose of conveying and pressing the wet paper. 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 use of the wet paper conveying belt to transfer the wet paper in the press section, at present, as a papermaking machine, a closed-draught papermaking machine is known, which transfers the wet paper by closed-draught for the purpose of running the wet paper. 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 section in which the wet paper is run alone, so that paper breakage is prevented. Thus, the closed-draught papermaking machine is excellent in terms of the adaptability to high-speed running and the stability of the operation.

[0005] On the other hand, in order to properly transfer the wet paper in the closed-draught papermaking machine, the wet paper conveying belt is required to have a function of conveying the wet paper in an attached state (wet paper adhesion property), and a function of smoothly separating the wet paper when the wet paper is transferred to the subsequent stage (wet paper peeling property). Thus, in order to achieve such 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] Patent Documents 1 and 2 disclose a wet paper conveying belt in which the wet paper-carrying surface of the resin layer that carries the wet paper has an arithmetic surface roughness within a prescribed range depending on 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] However, in a papermaking machine, wet paper is continuously transported at a high speed, for example, 1000 m / min or more. In such a severe environment, as the papermaking belt runs, the resin constituting the papermaking belt falls off due to friction, bending fatigue, and the like. If the resin of the papermaking belt falls off in this way, the intended performance of the papermaking belt, for example, in the case of a wet paper transporting belt, wet paper adhesion and wet paper peelability change, making it difficult for the papermaking belt to be used for a long period of time.

[0012] Also, in Patent Documents 1 and 2, wet paper adhesion and wet paper peelability are adjusted by adjusting the surface roughness of the resin layer and the swelling rate of the resin with respect to water. However, when the swelling rate of the resin with respect to water increases, the strength of the resin decreases, and the resin often falls off.

[0013] Therefore, an object of the present application is to provide a papermaking belt in which the resin of the resin layer falls off is inhibited and a manufacturing method of the papermaking belt.

[0014] Solution to the problem

[0015] In order to achieve the above object, the present inventors conducted intensive studies, as a result of which it was found that the resin falls off with cracks and raised portions of the surface of the papermaking belt of a prescribed size or more as a starting point, and that, if the number of cracks and raised portions per surface area of the surface of the papermaking belt is a prescribed number or less, the resin can be prevented from falling off. Furthermore, it was found that, when forming the resin layer of the papermaking belt, cracks and raised portions of the surface of the papermaking belt can be inhibited by using a resin composition containing an aqueous urethane resin dispersion and an organic solvent having a boiling point of a prescribed value or more. Moreover, through further studies, the present application was completed.

[0016] The gist of the present application is as follows:

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

[0018] the total number of raised portions having a height of 50 μm or more and cracks having a length of 10 mm or more on at least one side surface of the resin layer is 1.0 / m 2 the following papermaking machine.

[0019] [2] The papermaking belt according to [1], wherein the resin layer contains an aqueous urethane resin.

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

[0021] the resin layer is formed using a resin composition containing an aqueous urethane resin dispersion, the resin composition being used in a papermaking machine containing an organic solvent having a boiling point of 100°C or more at 1 atm.

[0022] [4] The papermaking belt according to [3], wherein the content of the organic solvent in the resin composition is 5.0 mass% or more and 30 mass% or less.

[0023] [5] The papermaking belt according to [3] or [4], wherein the organic solvent includes an organic solvent having a boiling point of 170°C or higher at 1 atm.

[0024] [6] The papermaking belt according to any one of [3] to [5], wherein the vapor pressure of the organic solvent at 20°C is 200 Pa or lower.

[0025] [7] The papermaking belt according to any one of [3] to [6], wherein the organic solvent includes one or more selected from the group consisting of 1-methyl-2-pyrrolidinone, 1-ethyl-2-pyrrolidinone, dipropylene glycol dimethyl ether, 3-methoxy-N,N-dimethylpropanamide, and 3-butoxy-N,N-dimethylpropanamide.

[0026] [8] The papermaking belt according to any one of [3] to [6], wherein the organic solvent includes an organic solvent having a boiling point of 205°C or higher at 1 atm.

[0027] [9] The papermaking belt according to [8], wherein the organic solvent includes one or more selected from the group consisting of 1-ethyl-2-pyrrolidinone, 3-methoxy-N,N-dimethylpropanamide, and 3-butoxy-N,N-dimethylpropanamide.

[0028]

[10] The papermaking belt according to any one of [1] to [9], which is a wet paper conveyance belt.

[0029]

[11] The papermaking belt according to any one of [1] to [9], which is a shoe press belt.

[0030]

[12] A method for manufacturing a papermaking belt, comprising a step of forming at least one resin layer using a resin composition including an aqueous dispersion of urethane resin, the resin composition including an organic solvent having a boiling point of 100°C or higher at 1 atm.

[0031] Effects of the Invention

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

[0033] Figure 1 FIG. 1 is a schematic cross-sectional view of a papermaking belt according to an embodiment of the present application in the machine transverse direction.

[0034] Figure 2FIG. 1 is a photograph showing a bulging portion on a wet paper carrying surface of a wet paper conveying belt.

[0035] Figure 3 FIG. 2 is a cross-sectional view of a first resin layer showing a measuring method of a height of a bulging portion generated on a wet paper carrying surface of a wet paper conveying belt.

[0036] Figure 4 FIG. 3 is a schematic view for explaining a preferred embodiment of a manufacturing method of a papermaking belt of the present application.

[0037] Figure 5 FIG. 4 is a schematic view for explaining a preferred embodiment of a manufacturing method of a papermaking belt of the present application.

[0038] Figure 6 FIG. 5 is a schematic view for explaining a preferred embodiment of a manufacturing method of a papermaking belt of the present application.

[0039] Figure 7 FIG. 6 is a schematic view for explaining a preferred embodiment of a manufacturing method of a papermaking belt of the present application.

[0040] Figure 8 FIG. 7 is a schematic view for explaining an example of a papermaking machine to which a papermaking belt of the present application is applied.

[0041] Figure 9 FIG. 8 is a schematic view of a bending fatigue testing device used when a resin drop test is performed.

[0042] Figure 10 FIG. 9 is a cross-sectional view of a bulging portion formed on a wet paper conveying belt of Comparative Example 2. DETAILED DESCRIPTION

[0043] Hereinafter, a preferred embodiment of a papermaking belt of the present application and a manufacturing method of a papermaking belt will be explained in detail with reference to the accompanying drawings.

[0044] 1. Papermaking belt

[0045] First, a papermaking belt of a preferred embodiment of the present application will be explained.

[0046] Figure 1 FIG. 1 is a photograph showing a bulging portion on a wet paper carrying surface of a wet paper conveying belt.

[0047] Figure 1 A wet paper conveying belt (papermaking belt) 1 shown in FIG. 1 is a device for conveying and transferring a wet paper W in a press section of a papermaking machine. The wet paper conveying belt 1 is formed as a endless belt. That is, the wet paper conveying belt 1 is a ring-shaped belt. Further, the wet paper conveying belt 1 is usually arranged in such a manner that its circumferential direction is along a machine direction (MD) of a papermaking system.

[0048] The wet paper conveying belt 1 has a reinforcing fiber base material layer 13, a first resin layer (wet paper carrying side resin layer) 11 provided on one main surface of the reinforcing fiber base material layer 13 on the outer surface side, and a second resin layer (roll side resin layer) 15 provided on the other main surface on the inner surface side of the reinforcing fiber base material layer 13, which are stacked to form. Further, the first resin layer is a layer that forms an outer side surface (outer peripheral surface) of a ring formed by the wet paper conveying belt 1.

[0049] The first resin layer 11 is a layer provided on one main surface of the reinforcing fiber base material layer 13 and mainly composed of a resin 113.

[0050] The first resin layer 11 contacts the wet paper on the main surface on the opposite side of the main surface bonded to the reinforcing fiber base material layer 13 and constitutes a wet paper carrying surface 111 for carrying the wet paper W. 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.

[0051] In the present embodiment, the total number of the protrusion portions having a height of 50 μm or more and the cracks having a length of 10 mm or more on the wet paper carrying surface 111 of the first resin layer 11 is 1.0 per m 2 or less. Thus, the resin is inhibited from peeling off from the first resin layer 11. The present inventors have found that the resin peeling off from the first resin layer 11 is mostly caused by the protrusion portions and the cracks having a size of the prescribed level or more on the wet paper carrying surface 111. Further, the present inventors have found that the resin peeling off from the first resin layer 11 is inhibited by keeping the number of such protrusion portions and cracks at a certain level or less.

[0052] Further, the height of the protrusion portion generated on the wet paper carrying surface of the wet paper conveying belt can be measured as follows. Figure 2 is an enlarged photograph for illustrating the protrusion portion on the wet paper carrying surface of the wet paper conveying belt, Figure 3 is a cross-sectional pattern view of the first resin layer for a measurement method of the height of the protrusion portion generated on the wet paper carrying surface of the wet paper conveying belt. First, for the wet paper carrying surface of the wet paper conveying belt as shown in Figure 2 the protrusion portion is explored by vision and touch. In the exploration by vision, a microscope or the like can be used, but the judgment by visual observation is simple. Further, the above relatively high protrusion portion can also be easily judged by touch.

[0053] Next, the first resin layer of the wet paper conveying belt having the protrusions is subjected to cross-sectional observation, and the height of the protrusions is measured. The cross-sectional observation can be performed using, for example, an optical microscope such as a digital microscope. For example, in the case where a bubble X is generated in the first resin layer 11 of the wet paper conveying belt 1, at the same time, the resin 113 of the first resin layer 11 is pushed out to the wet paper carrying surface 111 side by the bubble X, and as a result, a protrusion Y is generated. Here, a straight line a passing through a region of the wet paper carrying surface 111 other than the protrusion Y is assumed. Next, a tangent line β passing through an apex YP of the protrusion Y and parallel to the straight line a is assumed. Further, a distance h between the straight line a and the tangent line β is defined as the protrusion height. Figure 3

[0054] Further, the cracks can be specified and observed by visually observing the wet paper carrying surface 111. Further, the length of the cracks can be obtained by measuring the length along the crack shape. In this case, the length of the cracks is not the straight line distance between the end points, but the length along the crack shape, and in the case where the cracks are bifurcated, the length of the bifurcated portions of the cracks is also included in the length of the cracks.

[0055] The total number of the protrusions having a height of 50 μm or more and the cracks having a length of 10 mm or more on the wet paper carrying surface 111 of the wet paper conveying belt 1 is preferably 1.0 per m2or less, more preferably 0.50 per m2or less, and further more preferably 0.20 per m2or less. By this, the protrusions and the cracks can be further inhibited from being generated on the wet paper carrying surface 111 of the wet paper conveying belt 1. 2 2 By this, the adhesion and the peeling properties of the above wet paper W on the wet paper conveying belt 1 are further more excellent.

[0056] Further, the arithmetic average roughness Ra of the wet paper carrying surface 111 based on JIS B0601 is not particularly limited, but is preferably 0.3 to 20 μm, more preferably 0.5 to 12.0 μm, and further more preferably 1.0 to 10.0 μm. By this, the adhesion and the peeling properties of the above wet paper W on the wet paper conveying belt 1 are further more excellent.

[0057] Further, in the present embodiment, the resin 113 constituting the first resin layer 11 is formed using a resin composition containing an aqueous urethane resin dispersion, and the resin composition contains an organic solvent having a boiling point of 100°C or more at 1 atm. By this, the generation of the protrusions and the cracks can be inhibited, and the number of the protrusions having a height of 50 μm or more and the cracks having a length of 10 mm or more can be more easily achieved as described above. The reason why the generation of the protrusions and the cracks can be inhibited in this way is not clear, but it is presumed as follows:

[0058] ​​As described above, since the resin composition contains the organic solvent having a relatively high boiling point, when the water and other low-boiling-point solvents contained in the resin composition are volatilized during the formation of the first resin layer 11, the organic solvent also remains, which can suppress a sharp rise in the viscosity of the resin composition and prevent the formation of a dry surface coating film. As a result, even if a bubble is generated by the volatilization of water or other low-boiling-point solvents, the bubble can be removed from the resin composition to suppress the occurrence of the protrusions. Also, the resin composition remains flexible even after the volatilization of water or other low-boiling-point solvents by containing the relatively high-boiling-point organic solvent, and is less likely to cause cracks due to the shrinkage of the resin composition caused by the volatilization of water or other low-boiling-point solvents. It is considered that the occurrence of the protrusions and cracks in the first resin layer 11 is suppressed by the above-described phenomena.

[0059] Also, the resin composition for forming the resin 113 contains the urethane resin aqueous dispersion. The urethane resin aqueous dispersion contains the aqueous urethane resin, which can form the first resin layer 11 composed of the aqueous urethane resin. Since the wet paper-carrying surface 111 of the first resin layer 11 is composed of such an aqueous urethane resin, the wet paper-carrying surface 111 has a hydrophilic property, and the adhesion of the wet paper-carrying surface 111 to the wet paper W is improved. Thus, by adjusting the surface roughness of the wet paper-carrying surface 111 to control the concavities and convexities, the adhesion and the peelability of the wet paper W can be easily controlled. Also, since the wet paper-carrying surface 111 of the first resin layer 11 has a hydrophilic property, the wet paper conveyor belt 1 is less likely to attach dirt during use.

[0060] On the other hand, in order to form the aqueous urethane resin, it is necessary to use the urethane resin aqueous dispersion, and in this case, as described above, there is a problem that the protrusions or cracks are easily generated due to the solvent or the dispersion medium such as water or a low-boiling-point organic solvent contained in the urethane resin aqueous dispersion. However, in the present embodiment, the resin composition contains the relatively high-boiling-point organic solvent, thereby suppressing the problems caused by the urethane resin aqueous dispersion.

[0061] Hereinafter, the resin composition for forming the resin 113 will be described. The resin composition contains an organic solvent having a boiling point of 100°C or higher at least 1 atm (hereinafter, simply referred to as "high-boiling-point solvent") and a urethane resin aqueous dispersion.

[0062] As the high-boiling solvent, there is no particular limitation as long as it is an organic solvent having a boiling point of 100°C or higher at 1 atm, and a known organic solvent can be used alone or in combination of two or more. As such a high-boiling solvent, there is no particular limitation, and for example, includes a lactam ring-containing solvent such as 1-methyl-2-pyrrolidinone (204°C), 1-ethyl-2-pyrrolidinone (218°C), and the like, an amide solvent such as 3-methoxy-N,N-dimethylpropionamide (215°C), dimethylformamide (153°C), dimethylacetamide (165°C), 3-butoxy-N,N-dimethylpropionamide (252°C), and the like, an acid ether ester solvent such as 3-ethoxypropyl acetate (165°C), and the like, a ketone solvent such as diisobutyl ketone (168°C), isophorone (215°C), and the like, a sulfoxide solvent such as dimethyl sulfoxide (189°C), and the like, a glycol solvent such as ethylene glycol (197°C), 1,3-butanediol (207°C), and the like, a glycol ester solvent such as 1,4-butanediol diacetate (230°C), 1,3-butanediol diacetate (232°C), diethylene glycol monobutyl ether acetate (247°C), 1,6-hexanediol diacetate (260°C), and the like, a glycol ether solvent such as diethylene glycol monoethyl ether (196°C), diethylene glycol monobutyl ether (230°C), triethylene glycol monobutyl ether (278°C), dipropylene glycol dimethyl ether (175°C), dipropylene glycol n-propyl ether (212°C), dipropylene glycol methyl n-propyl ether (203°C), dipropylene glycol n-butyl ether (230°C), dipropylene glycol methyl n-butyl ether (227°C), tripropylene glycol methyl ether (241°C), tripropylene glycol n-butyl ether (276°C), dipropylene glycol phenyl ether (243°C), dipropylene glycol methyl ether acetate (209°C), diethylene glycol monoethyl ether acetate (218°C), and the like, an alcohol solvent such as benzyl alcohol (205°C), and the like, and an ester solvent such as triacetin (259°C), dimethyl glutarate (214°C), γ-butyrolactone (204°C), and the like. Also, each temperature in parentheses represents the boiling point of each compound at 1 atm.

[0063] Among the above, the high-boiling solvent preferably includes one or more selected from the group consisting of a lactam ring-containing solvent, an amide solvent, and a glycol ether solvent; more preferably includes one or more selected from the group consisting of 1-methyl-2-pyrrolidinone, 1-ethyl-2-pyrrolidinone, dipropylene glycol dimethyl ether, 3-methoxy-N,N-dimethylpropionamide, and 3-butoxy-N,N-dimethylpropionamide; more preferably includes one or more selected from the group consisting of 1-ethyl-2-pyrrolidinone, dipropylene glycol dimethyl ether, 3-methoxy-N,N-dimethylpropionamide, and 3-butoxy-N,N-dimethylpropionamide; and further preferably includes one or more selected from the group consisting of 1-ethyl-2-pyrrolidinone, 3-methoxy-N,N-dimethylpropionamide, and 3-butoxy-N,N-dimethylpropionamide.

[0064] Further, the boiling point of each of the organic solvents constituting the high-boiling-point solvent at 1 atm can be 100°C or higher, and the high-boiling-point solvent preferably includes an organic solvent having a boiling point of 170°C or higher; more preferably includes an organic solvent having a boiling point of 200°C or higher at 1 atm; and further preferably includes an organic solvent having a boiling point of 205°C or higher at 1 atm. Thus, the above effects of the high-boiling-point solvent can be more effectively exerted, and as a result, the occurrence of the protrusions and cracks can be further suppressed.

[0065] Further, the vapor pressure of the high-boiling-point solvent at 20°C is not particularly limited, but is, for example, 200 Pa or lower; preferably 150 Pa or lower; and more preferably 100 Pa or lower. Thus, the above effects of the high-boiling-point solvent can be more effectively exerted, and as a result, the occurrence of the protrusions and cracks can be further suppressed.

[0066] Further, the content of the high-boiling-point solvent in the resin composition is not particularly limited, but is, for example, 1 mass% or more and 40 mass% or less; preferably 5 mass% or more and 30 mass% or less; and more preferably 7 mass% or more and 25 mass% or less.

[0067] The urethane resin aqueous dispersion is a dispersion in which an aqueous urethane resin is dispersed in an aqueous dispersion medium. As the urethane resin aqueous dispersion, there are anionic, nonionic, or cationic self-emulsified urethane resin aqueous dispersion emulsified by self-emulsification, and a forcedly emulsified urethane resin aqueous dispersion emulsified by forced emulsification using an emulsifier or the like, and one of them can be used, or both of them can be used in combination. The urethane resin aqueous dispersion contains at least an aqueous urethane resin and an aqueous dispersion medium.

[0068] The aqueous urethane resin is formed using a polyisocyanate compound, a polyol, and a curing agent (as needed). Therefore, the polyisocyanate compound, the polyol, and the curing agent constituting the urethane resin are described below.

[0069] As the polyisocyanate compound, aromatic polyisocyanate compounds and aliphatic polyisocyanate compounds can be exemplified, and one of these can be used alone or two or more kinds thereof can be used in combination. As the aromatic polyisocyanate compound, 2,4-toluene diisocyanate (2,4-TDI), 2,6-toluene diisocyanate (2,6-TDI), 4,4'-methylenebis(isocyanatophenyl) (MDI), p-phenylene diisocyanate (PPDI), dimethyl diphenyl diisocyanate (TODI), 1,5-naphthalene diisocyanate (NDI), 4,4-dibenzyl diisocyanate (DBDI), xylylene diisocyanate (XDI), tetramethyl xylylene diisocyanate (TMXDI), polymeric methylene polyphenyl polyisocyanate (polymeric MDI), and the like can be exemplified. The aliphatic polyisocyanate compound is not particularly limited, but chain aliphatic polyisocyanate compounds such as 1,6-hexamethylene diisocyanate (HDI), 1,5-pentamethylene diisocyanate, and the like, or alicyclic polyisocyanate compounds such as 1-isocyanato-3-isocyanatomethyl-3,5,5-trimethylcyclohexane (IPDI), dicyclohexylmethane-4,4'-diisocyanate (H12MDI), 1,3-cyclohexyl diisocyanate, 1,4-cyclohexyl diisocyanate (CHDI), and 1,3-bis(isocyanatomethyl)cyclohexane, 1,4-bis(isocyanatomethyl)cyclohexane (H6XDI), and the like can be exemplified, and one of these can be used alone or two or more kinds thereof can be used in combination.

[0070] Further, the aqueous urethane resin generally contains an aliphatic polyisocyanate compound. Among the above, the aqueous urethane resin preferably contains one or more selected from the group consisting of 1-isocyanato-3-isocyanatomethyl-3,5,5-trimethylcyclohexane (IPDI), dicyclohexylmethane-4,4'-diisocyanate (H12MDI), and 1,6-hexamethylene diisocyanate (HDI).

[0071] As the polyol compound, there is no particular limitation, and long-chain polyol compounds such as polyester polyols such as polycaprolactone polyol, polyethylene adipate, and the like, polyether polyols such as polyethylene glycol, polyoxypropylene glycol, polyhexamethylene ether glycol, polytetramethylene ether glycol (PTMG), and the like, polycarbonate polyols such as polycarbonate diol, and the like, silicone polyols such as polyether carbonate diol, trimethylolpropane, polybutadiene polyol, perfluoropolyether polyol, silicone diol, and the like can be exemplified, and one of these can be used alone or two or more kinds thereof can be used in combination.

[0072] Further, the polycarbonate polyol is not particularly limited, but for example, a polycarbonate polyol synthesized from a polycarbonate polyol raw material polyol and a polycarbonate source can be exemplified. Further, the polycarbonate polyol raw material polyol is not particularly limited, but for example, a linear or branched alkylene glycol having 2 to 20 carbon atoms, a hydroxyl group-containing cyclic hydrocarbon having 3 to 20 carbon atoms, or the like can be exemplified, and one of these can be used alone, or two or more of these can be used in combination. As the linear alkylene glycol, for example, ethylene glycol, propylene glycol, butylene glycol, pentylene glycol, hexylene glycol, heptylene glycol, octylene glycol, nonylene glycol, decylene glycol, undecylene glycol, dodecylene glycol, or the like can be exemplified. As the branched alkylene glycol, for example, 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2-methyl-1,8-octanediol, or the like can be exemplified. As the hydroxyl group-containing cyclic hydrocarbon, for example, 1,3-cyclohexanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, or the like can be exemplified.

[0073] The curing agent having an active hydrogen group is not particularly limited, and one or two or more compounds selected from the group consisting of a polyol compound and a polyamine can be used.

[0074] As the polyol compound that can be contained in the curing agent, various aliphatic polyol compounds and various alicyclic or aromatic polyol compounds can be used in addition to the above-described long-chain polyol compound.

[0075] The aliphatic polyol compound is not particularly limited, and for example, an alkylene glycol compound such as 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, 1,13-tridecanediol, 1,14-tetradecanediol, 1,16-hexadecanediol, 1,18-octadecanediol, 1,20-eicosanediol, 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, or the like, or glycerol, ditrimethylolpropane, trimethylolpropane (TMP), pentaerythritol, dihydroxymethylpropionic acid (DHPA), or the like can be exemplified.

[0076] The alicyclic polyol compound is not particularly limited, and for example, 1,4-cyclohexanedimethanol, hydrogenated bisphenol A, or the like can be exemplified.

[0077] The aromatic polyol compound is not particularly limited, and examples thereof include hydroquinone bis-β-hydroxyethyl ether (HQEE), hydroxyquinone resorcinol (HER), 1,3-bis(2-hydroxyethoxybenzene), 1,4-bis(2-hydroxyethoxybenzene), bisphenol A, an alkylene oxide adduct of bisphenol A, bisphenol S, an alkylene oxide adduct of bisphenol S, and the like.

[0078] The polyamine is not particularly limited, and examples thereof include hydrazine, ethylenediamine, 4,4'-methylene-bis-(2-chloroaniline) (MOCA), dimethylthioltoluenediamine (DMTDA), diethyltoluenediamine (DETDA), trimethyleneglycol bis(p-aminobenzoate) (TMAB), 4,4'-methylene-bis-(3-chloro-2,6-diethyl aniline) (MCDEA), 4,4'-methylene-bis-(2,6-diethyl aniline) (MDEA), triisopropanolamine (TIPA), p-bis(aminocyclohexyl)methane (PACM), 1,5-naphthalenediamine, phenylenediamine, benzidine, toluene-2,4-diamine, t-butyltoluene diamine, 1,2-bis(2-amino phenylsulfidoethane), 2-(2-aminoethylamino)ethanol, and the like.

[0079] Further, the isocyanate compound, the polyol, and / or the curing agent described above can also be substituted with one or more hydrophilic groups. That is, the aqueous urethane resin can also have one or more hydrophilic groups. Thereby, it is easy to self-disperse in water, and it is easy to obtain a urethane resin aqueous dispersion. Further, since the aqueous urethane resin has a hydrophilic group, it is possible to improve the hydrophilicity of the wet paper carrying surface 111 of the wet paper conveyor belt 1, and to improve the adhesion of the wet paper. The hydrophilic group is not particularly limited, but examples thereof include a carboxyl group, a sulfo group, a phosphoric acid group, a hydroxyl group, a phenolic hydroxyl group, an amino group, and the like. One of these hydrophilic groups can be substituted, or two or more of them can be substituted. Further, two or more compounds can be substituted with a hydrophilic group, and in this case, the hydrophilic groups that are substituted can be the same or different among the compounds.

[0080] Further, among the above, the carboxyl group, the sulfo group, the phosphoric acid group, the hydroxyl group, the phenolic hydroxyl group, the amino group, and the like can serve as a crosslinking point of the crosslinking agent described below, and contribute to improving the water resistance and durability of the first resin layer 11. Therefore, the isocyanate compound, the polyol, and / or the curing agent preferably include one or more selected from the group consisting of a carboxyl group, a sulfo group, a phosphoric acid group, a hydroxyl group, a phenolic hydroxyl group, and an amino group.

[0081] Further, when a polyol having three or more hydroxyl groups such as glycerin, ditrimethylolpropane, trimethylolpropane (TMP), pentaerythritol, or the like, or a polyol having a hydrophilic group other than a hydroxyl group such as dimethylolpropionic acid (DHPA) or the like is used, it is possible to easily introduce a hydrophilic group into the aqueous urethane resin.

[0082] The aqueous dispersion medium mainly contains water, and further optionally contains an organic solvent. There is no particular limitation as to the organic solvent, and for example, alcoholic solvents such as methanol, ethanol, 1-propanol, isopropanol, 1-butanol, 2-butanol, isobutanol, tert-butanol, benzyl alcohol, and the like; glycol solvents such as methanediol, 1,2-ethanediol (ethylene glycol), 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol (1,3-butanediol), 1,4-butanediol, 2,3-butanediol, 2-buten-1,4-diol, 1,4-butanediol, diethylene glycol, and the like; other polyvalent alcoholic solvents such as 3-methoxy-1,2-propanediol, glycerol, and the like; glycol ester solvents such as 1,4-butanediol diacetate, 1,3-butanediol diacetate, diethylene glycol monobutyl ether acetate, 1,6-hexanediol diacetate, and the like; glycol ether solvents such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, dipropylene glycol dimethyl ether, propylene glycol monomethyl ether propionate, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, dipropylene glycol dimethyl ether, dipropylene glycol n-propyl ether, dipropylene glycol methyl n-propyl ether, dipropylene glycol n-butyl ether, dipropylene glycol methyl n-butyl ether, tripropylene glycol methyl ether, tripropylene glycol n-butyl ether, dipropylene glycol phenyl ether, dipropylene glycol methyl ether acetate, diethylene glycol monoethyl ether acetate, and the like; ketone solvents such as acetone, methyl ethyl ketone, methyl propyl ketone, methyl isobutyl ketone, diethyl ketone, dipropyl ketone, diisobutyl ketone, cyclohexanone, diacetone alcohol, isophorone, and the like; ether solvents such as dimethyl ether, diethyl ether, di-n-propyl ether, diisopropyl ether, di-n-butyl ether, di-t-butyl ether, t-butyl methyl ether, 1,4-dioxane, tetrahydrofuran, and the like; ester solvents such as ethyl acetate, methyl acetate, butyl acetate, sec-butyl acetate, methoxybutyl acetate, amyl acetate, n-propyl acetate, isopropyl acetate, methyl lactate, ethyl lactate, butyl lactate, triacetin, γ-butyrolactone, dimethyl glutarate, and the like; acid ether ester solvents such as 3-ethoxypropyl acetate and the like; carbonate solvents such as dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, and the like; halogenated solvents such as dichloromethane, trichloroethylene, perchloroethylene, 1-bromopropane, chloroform, carbon tetrachloride, and the like; solvents containing a lactam ring such as 2-pyrrolidone, 1-methyl-2-pyrrolidone, 1-ethyl-2-pyrrolidone, and the like; amide solvents such as 3-methoxy-N,N-dimethylpropanamide, dimethylformamide, dimethylacetamide, 3-butoxy-N,N-dimethylpropanamide, and the like; sulfolane; morpholine; acetonitrile; propionitrile; and the like can be used alone or in combination of two or more.

[0083] Further, as listed above, the aqueous dispersion medium can further contain the above-mentioned high-boiling-point solvent as the organic solvent. In this case, the work of separately adding the high-boiling-point solvent to the resin composition can be omitted.

[0084] Further, the urethane resin aqueous dispersion can further include an emulsifier. As the emulsifier, any emulsifier can be used alone or two or more kinds of emulsifiers can be used in combination.

[0085] The urethane resin aqueous dispersion described above includes, in the resin composition, for example, 5 mass% or more and 90 mass% or less; preferably 10 mass% or more and 70 mass% or less; more preferably 15 mass% or more and 50 mass% or less of the aqueous urethane resin.

[0086] Further, the resin composition can further include a crosslinking agent. Since the resin composition includes the crosslinking agent, the aqueous urethane resin is crosslinked, and the strength of the first resin layer 11 is improved. As such a crosslinking agent, there is no particular limitation, and for example, a carbodiimide-based crosslinking agent, a melamine-based crosslinking agent, an epoxy-based crosslinking agent, an isocyanate-based crosslinking agent, and the like can be exemplified.

[0087] The content of the crosslinking agent in the resin composition is not particularly limited, and for example, is 0.1 mass% or more and 30 mass% or less; preferably 0.5 mass% or more and 20 mass% or less; more preferably 1.0 mass% or more and 10 mass% or less.

[0088] Further, the resin composition can optionally include a pH adjustor such as ammonia or the like, a leveling agent such as a nonionic acetylene diol or the like, a defoaming agent such as sesame oil, a metal soap, a nonionic surfactant, or the like, a viscosity adjustor such as an acrylic resin emulsion or the like.

[0089] Further, the resin composition can further include a thermosetting resin such as a urethane resin other than the aqueous urethane resin, an epoxy resin, an acrylic resin, or the like, or a thermoplastic resin such as a polyamide resin, a polyarylate resin, a polyester resin, or the like.

[0090] Further, the resin 113 constituting the first resin layer 11 can include a combination of one or more kinds of inorganic fillers such as titanium oxide, kaolin, clay, talc, diatomaceous earth, calcium carbonate, calcium silicate, magnesium silicate, silicon dioxide, mica, and the like. That is, the resin composition can also include the above inorganic fillers.

[0091] Further, the composition and type of the resin material and the inorganic filler in the first resin layer 11 can be different for each portion in the first resin layer 11, or can be the same.

[0092] Further, the first resin layer 11 preferably has a water-impermeable property. That is, the first resin layer 11 is preferably water-impermeable.

[0093] The reinforcing fiber base material layer 13 is composed of a reinforcing fiber base material 131 and a resin 133. The resin 133 is present in the reinforcing fiber base material layer 13 in a manner to fill the interstices of the reinforcing fiber base material 131. That is, a part of the resin 133 is impregnated into the reinforcing fiber base material 131, and on the other hand, the reinforcing fiber base material 131 is embedded in the resin 133.

[0094] The reinforcing fiber base material 131 is not particularly limited, but a fabric obtained by weaving warp and weft yarns by a loom or the like is generally used. Also, a lattice-shaped material made by overlapping warp and weft yarns can be used without weaving.

[0095] The fineness of the fiber constituting the reinforcing fiber base material 131 is not particularly limited, but for example, it can be 300 to 10,000 dtex; preferably, it can be 500 to 6,000 dtex.

[0096] Also, the fineness of the fiber constituting the reinforcing fiber base material 131 can be different depending on the position of use of the fiber. For example, the warp and weft yarns of the reinforcing fiber base material 131 can have different finenesses.

[0097] As the material of the reinforcing fiber base material 131, 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. can be used alone or two or more kinds thereof can be used in combination.

[0098] The material of the resin 133 is not particularly limited, and for example, various resins that can be used for the resin 113 of the above-described first resin layer 11 can be used alone or two or more kinds thereof can be used in combination. Alternatively, the resin 133 can also include a thermosetting resin such as an urethane resin other than a waterborne urethane resin, an epoxy resin, an acrylic resin, etc., or a thermoplastic resin such as a polyamide resin, a polyarylate resin, a polyester resin, etc. The kind and composition of the resin 133 can be the same as or different from the resin 113 constituting the first resin layer 11.

[0099] Also, the kind and composition of the resin 133 in the reinforcing fiber base material layer 13 can be different at each position in the reinforcing fiber base material layer 13 or can be the same.

[0100] The second resin layer (roller surface side resin layer) 15 is a layer provided on one main surface of the reinforcing fiber base material layer 13 and mainly composed of a resin 153.

[0101] The second resin layer 15 constitutes a roll contact surface 151 for contacting a roll described below on a main surface opposite to the main surface joined to the reinforcing fiber base material layer 13. The wet paper conveying belt 1 can obtain a power for conveying wet paper from a roll by contacting the roll contact surface 151 with the roll during use.

[0102] As the resin 153 constituting the second resin layer 15, a resin material that can be used for the first resin layer 11 or the reinforcing fiber base material layer 13 described above can be used alone or two or more kinds thereof can be used in combination. The kind 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 reinforcing fiber base material layer 13.

[0103] In particular, as the resin 153 constituting the second resin layer 15, a urethane resin is preferable from the viewpoint of mechanical properties, wear resistance, and softness.

[0104] Also, like the first resin layer 11, the second resin layer 15 can contain one or more kinds of inorganic fillers.

[0105] Also, the composition and kind of the resin material and the inorganic filler in the second resin layer 15 can be different or the same among each part of the second resin layer 15.

[0106] The size of the wet paper conveying belt 1 described above is not particularly limited and can be appropriately set according to the use.

[0107] For example, the width of the wet paper conveying belt 1 is not particularly limited but can be 700 to 13500 mm; preferably, can be 2500 to 12500 mm.

[0108] Also, for example, the length (circumferential length) of the wet paper conveying belt 1 is not particularly limited but can be 4 to 35 m; preferably, can be 10 to 30 m.

[0109] Also, the thickness of the wet paper conveying belt 1 is not particularly limited but, for example, can be 1.5 to 7.0 mm; preferably, can be 2.0 to 6.0 mm.

[0110] Also, the thickness of each part of the wet paper conveying belt 1 can be different or the same.

[0111] For example, the wet paper conveying belt 1 described above can be manufactured by the wet paper conveying belt manufacturing method of the present embodiment described below.

[0112] In the wet paper conveying belt 1 of the present embodiment described above, the total number of the protrusion parts having a height of 50 μm or more and the cracks having a length of 10 mm or more on the wet paper carrying surface 111 of the first resin layer 11 is 1.0 per m 2The resin is thus inhibited from peeling off from the first resin layer 11. Furthermore, in the present embodiment, the first resin layer 11 of the wet paper conveying belt 1 is formed using a resin composition containing an aqueous urethane resin dispersion, the resin composition containing an organic solvent having a boiling point of 100°C or higher at 1 atm. The generation of the protrusions and the cracks can thus be inhibited, and the protrusions having a height of 50 μm or more and the cracks having a length of 10 mm or more as described above can be more easily achieved.

[0113] As a modification of the wet paper conveying belt 1 described above, the reinforcing fiber base material 131 can be needle-punched on the wet paper-carrying side and / or the roll side with a fiber that has a layer impregnated with the resin material described above in its interfacing fiber. Furthermore, as the material of the interfacing fiber, a material that can be used for the reinforcing fiber base material 131 can be used alone or in combination with two or more.

[0114] <2. Method for manufacturing papermaking belt>

[0115] Next, one example of a preferred embodiment of the method for manufacturing the papermaking belt of the present application will be described. Figures 4 to 7 FIG. 1 is a schematic view showing one example of a preferred embodiment of the method for manufacturing the papermaking belt of the present application.

[0116] The method for manufacturing the papermaking belt of the present application includes a step of forming at least one resin layer using a resin composition containing an aqueous urethane resin dispersion, the resin composition containing an organic solvent having a boiling point of 100°C or higher at 1 atm. Hereinafter, the wet paper conveying belt 1 will be described as one example of the papermaking belt. The method for manufacturing the wet paper conveying belt 1 of the present embodiment thus includes a step (laminating step) of forming a ring-shaped laminated body 1' having the second resin layer (roll side resin layer) 15 as the innermost layer and the first resin layer (wet paper-carrying side resin layer) 11 as the outermost layer.

[0117] In the laminating step, the ring-shaped belt-shaped laminated body 1' having the second resin layer 15 as the innermost layer and the precursor of the first resin layer 11' as the outermost layer is formed. The laminated body 1' can be formed using any method, but in the present embodiment, first, the reinforcing fiber base material layer 13 is formed by applying the resin material (resin composition) of the second resin layer 15 to the reinforcing fiber base material 131 in such a manner that the resin material penetrates through the reinforcing fiber base material 131, and, at the same time, the second resin layer 15 is formed on the inner side of the reinforcing fiber base material layer 13. Next, the precursor of the wet paper-carrying side resin layer 11' is formed by applying the resin composition of the wet paper-carrying side resin layer 11 to the outer surface of the formed reinforcing fiber base material layer 13.

[0118] Specifically, as shown in FIG. 1, the precursor of the wet paper-carrying side resin layer 11' is formed by applying the resin composition of the wet paper-carrying side resin layer 11 to the outer surface of the reinforcing fiber base material layer 13. Figure 4As shown, the annular strip-shaped reinforcing fiber substrate 131 is placed in contact with two rollers 21 arranged side by side.

[0119] Next, as Figure 5 As shown, a resin composition constituting the second resin layer 15 is applied to the outer surface of the reinforcing fiber substrate 131. Any method can be used to apply the resin composition, but in this embodiment, the resin composition is applied to the reinforcing fiber substrate 131 by discharging it from the resin outlet 25 while rotating the reinforcing fiber substrate 131 using a roller 21. Furthermore, the simultaneously applied resin composition is uniformly coated onto the reinforcing fiber substrate 131 using a coating rod 23. At this time, the coated resin composition can penetrate the reinforcing fiber substrate 131. Therefore, in this embodiment, not only can the resin 133 contained in the reinforcing fiber substrate 131 be formed, but also the resin 153 constituting the second resin layer 15 can be formed, and the reinforcing fiber substrate layer 13 and the second resin layer 15 can be formed simultaneously.

[0120] Next, as Figure 6 As shown, a resin composition constituting the first resin layer 11 is applied to the outer surface of the formed reinforcing fiber substrate layer 13. The resin composition can be applied using any method; in this embodiment, it is applied to the outer surface of the reinforcing fiber substrate layer 13 by discharging the resin composition from the resin outlet 25 while rotating the formed reinforcing fiber substrate layer 13 and the second resin layer 15 using a roller 21. The simultaneously applied resin composition is then uniformly coated using a coating rod 23. Furthermore, the resin composition constituting each layer can also be applied as a mixture with the aforementioned inorganic filler.

[0121] Furthermore, as described above, in this embodiment, in this process, the resin 113 of the first resin layer 11 is formed from the resin composition described above containing a high-boiling-point solvent. Moreover, as... Figure 6 As shown, a resin composition constituting the first resin layer 11 is applied to the outer surface of the reinforcing fiber substrate layer 13. This suppresses bulges or cracks that occur during the formation of the first resin layer 11. Specifically, since the resin composition contains a relatively high-boiling-point organic solvent, organic solvents remain even after water or other low-boiling-point solvents in the resin composition evaporate during the formation of the first resin layer 11. This suppresses a sharp increase in the viscosity of the resin composition and prevents the formation of a drying surface coating. Consequently, even if bubbles are generated due to the evaporation of water or other low-boiling-point solvents, these bubbles are removed from the resin composition, thereby suppressing the formation of bulges. Furthermore, after the water or other low-boiling-point solvents evaporate, the resin composition remains flexible due to the presence of a relatively high-boiling-point organic solvent, making it less prone to cracking caused by shrinkage of the resin composition due to the evaporation of water or other low-boiling-point solvents.

[0122] Next, the coated resin composition is dried and crosslinked. Thus, a laminate 1'in which the precursor 11'of the first resin layer, the reinforcing fiber base material layer 13, and the second resin layer 15 are sequentially stacked from the outer surface is obtained. The method of drying and crosslinking the resin material is not particularly limited, but can be performed by, for example, heating, UV irradiation, or the like.

[0123] Also, when the resin composition is dried and crosslinked by heating, for example, a far infrared heater, a hot air method, or the like can be used.

[0124] Also, when the resin composition is dried and crosslinked by heating, the heating temperature of the resin composition is preferably 60 to 150°C; more preferably 90 to 140°C. Also, for example, the heating time can be 0.5 to 30 hours; preferably 1 to 25 hours.

[0125] Next, the surface roughness of the outer surface of the precursor 11'of the wet paper carrying side resin layer is adjusted, and a wet paper carrying side resin layer 11 having a wet paper carrying surface 111 is formed (roughness adjustment step). Thus, a wet paper conveyor belt 1 as a papermaking belt in which the wet paper carrying surface 111 is formed is obtained.

[0126] For example, the surface roughness of the outer surface can be adjusted by grinding processing and / or polishing processing. Specifically, as shown in FIG. 6, this is performed by bringing a grinding device 27 or a polishing processing device (not shown) into contact with the laminate 1'placed in a state between the two rollers 21. Thus, the arithmetic mean roughness of the wet paper carrying surface 111 can be set to a desired value. Figure 5

[0127] Also, when the wet paper carrying surface 111 of the wet paper conveyor belt 1 is in a desired state before the grinding processing or the polishing processing, the grinding processing and / or the polishing processing can be omitted.

[0128] Also, in the above-described method of manufacturing a papermaking belt, the roller side resin composition is made to penetrate from the outer surface of the reinforcing fiber base material 131, and the second resin layer 15 is formed on the inner surface (penetration manufacturing method). However, the resin composition constituting the second resin layer 15 is given to the outer surface of the reinforcing fiber base material 131, and after the second resin layer 15 that is laminated to the reinforcing fiber base material layer 13 and the outer surface is formed, the resin composition of the first resin layer 11 can also be applied to the outer surface of the reinforcing fiber base material layer 13 (which is the inner surface before the turning) by turning the inside and outside thereof, to form the precursor 11'of the first resin layer (turning manufacturing method).

[0129] ​Further, as a modification of the above method of manufacturing the papermaking belt, there is a method of using a reinforcing fiber base material in which the wet paper carrying side and / or the roll side of the reinforcing fiber base material is needle punched with interfacing fibers. Thus, a wet paper conveyor belt (papermaking belt) having a first resin layer and / or a second resin layer in which the interfacing fiber layer is impregnated with a resin composition can be obtained.

[0130] 3. Papermaking machine

[0131] Next, an example of a papermaking machine using the papermaking belt according to the present application will be described. Figure 8 FIG. 1 is a schematic view of an example of a papermaking machine using a papermaking belt according to the present application for illustrating the present application. Figure 8 The illustrated papermaking machine is provided with a wire section 30, a press section 40, and a dryer section 50. In the drawing, the wet paper W shown by the broken line is carried from the wire section 30 to the press section 40 and the dryer section 50 in this order, and is dehydrated, squeezed, and dried to become paper in the process of being carried. Further, the following papermaking machine is a so-called closed-draft papermaking machine. Therefore, in the conveyance of the wet paper W in the press section 40, the wet paper W is carried by any one of the wet paper conveyor belt 1 and the press felts 41, 42, 43, and there is no part that is operated alone.

[0132] The wire section 30 holds the paper pulp on the wire 31 and dehydrates it to form a sheet-shaped wet paper W. The wire section 30 has a well-known structure, and the description of the main part thereof will be omitted. The wet paper W dehydrated in the wire section 30 is carried by the wire 31 supported by the guide roll 33 and carried to the press felt 41 of the press section 40.

[0133] The press section 40 is composed of a roll press section 40A and a shoe press section 40B. The roll press section 40A mainly includes the press felts 41, 42, press rolls 44A, 44B, suction rolls 45A, 45B, and guide rolls 48.

[0134] The press felts 41, 42 are endless belt-like bodies that carry and convey the wet paper W. The press felts 41, 42 are arranged so as to pass between the press rolls 44A and 44B and are supported by the plurality of guide rolls 48 and the suction rolls 45A, 45B. The suction roll 45A is arranged so that the press felt 41 supported on the front side in the direction of conveyance (flow direction) of the wet paper W abuts against the wire 31. The wet paper W is attracted by the suction roll 45A, and thereby the wet paper W is conveyed from the wire 31 to the press felt 41.

[0135] The press rolls 44A, 44B constitute a roll press mechanism 44 that, together with the press felts 41, 42, presses and squeezes the wet paper W and squeezes out the water from the wet paper W. The suction roll 45B is arranged so as to support the press felt 42 on the inner side in the direction of conveyance (flow direction) of the wet paper W, and to attract the wet paper W carried on the press felts 41, 42, peel off from the press felt 41, and be carried only on the press felt 42.

[0136] The shoe press section 40B mainly includes the wet paper conveying belt 1, a press felt 43, a shoe press mechanism 46, a suction roll 47, and guide rolls 48. The wet paper conveying belt 1 is as described above. The press felt 43 is an endless belt-like body that carries and conveys the wet paper W. The wet paper conveying belt 1 and the press felt 43 are arranged so as to pass through the shoe press mechanism 46, supported by the plurality of guide rolls 48 and the suction roll 47.

[0137] The suction roll 47 is arranged so that the press felt 43 supported on the front side in the conveying direction (flow direction) of the wet paper W is in contact with the press felt 42. Also, the wet paper W is attracted by the suction roll 47, and thus the wet paper W is conveyed from the press felt 42 to the press felt 43.

[0138] The shoe press mechanism 46 has a press roll 46A, a shoe 46B, and a shoe press belt 46C. The shoe 46B has a recess corresponding to the shape of the press roll 46A, and presses the wet paper W carried on the wet paper conveying belt 1 and the press felt 43 together with the press roll 46A via the shoe press belt 46C. Among them, the wet paper W carried on the press felt 43 conveyed to the shoe press mechanism 46 is arranged so as to be carried on the wet paper conveying belt 1 after passing through the shoe press mechanism 46.

[0139] In the drying section 50, the wet paper W is dried. The drying section 50 has a well-known configuration, and the main part thereof is omitted from the description. The drying section fabric 53 of the drying section 50 is supported by the suction roll 51 and abuts against the wet paper conveying belt 1. Also, the wet paper W is attracted by the suction roll 51, and thus the wet paper W is conveyed from the wet paper conveying belt 1 to the drying section fabric 53.

[0140] Among them, the running state of the wet paper W in the above-described paper machine is described. Also, of course, since the wet paper W has a continuous structure, the moving state of a part of the wet paper W is described.

[0141] First, the wet paper W passes through the wire 31 of the wire section 30, the press felt 41 of the press section 40, and the roll press mechanism 44 in this order, and is conveyed from the press felt 42 to the press felt 43. Also, it is conveyed to the shoe press mechanism 46 via the press felt 43. In the shoe press mechanism 46, the wet paper W is pressed by the shoe 46B via the shoe press belt 46C and the press roll 46A in a state of being sandwiched by the press felt 43 and the wet paper conveying belt 1.

[0142] At this time, the press felt 43 has high water permeability, and the wet paper conveying belt 1 has very low water permeability. Due to this, in the shoe press mechanism 46, the moisture from the wet paper W is transferred to the press felt 43.

[0143] After leaving the shoe press mechanism 46, the press felt 43, the wet paper W, and the wet paper conveyer 1 expand in volume due to the abrupt release of pressure. Due to the expansion and the capillary phenomenon of the pulp fibers constituting the wet paper W, a part of the moisture in the press felt 43 is transferred to the wet paper W, and a so-called rewetting phenomenon occurs.

[0144] However, as described above, since the wet paper conveyer 1 has a very low water permeability, the inside thereof does not retain moisture. Thus, the wet paper conveyer 1 is less likely to undergo the rewetting phenomenon, and the wet paper conveyer 1 contributes to the improvement of the wet paper dewatering efficiency. Also, the wet paper W leaving the shoe press mechanism 46 is conveyed by the wet paper conveyer 1. Further, the wet paper W is sucked by the suction roll 51 and conveyed by the dryer fabric 53 to the dryer 50.

[0145] Among the wet paper-carrying surface (outer circumferential surface) 111 of the wet paper-carrying-side resin layer (first resin layer) 11, the wet paper conveyer 1 requires the following functions: a function of conveying in a state of being attached to the wet paper W after leaving the shoe press mechanism 46 (wet paper adhesiveness) and a function of smoothly separating the wet paper W when conveying the wet paper W to the next stage (wet paper peelability). As such, the wet paper conveyer 1 needs to have opposite functions, and it is necessary to strictly control the adhesiveness of the wet paper W to the wet paper-carrying surface 111 of the wet paper conveyer 1.

[0146] However, when a conventional wet paper conveyer is used, the resin constituting the wet paper conveyer is peeled off due to friction or bending fatigue and the like while the wet paper conveyer is running. If the resin of the papermaking belt is peeled off in this way, the intended performance of the papermaking belt, such as the wet paper adhesiveness and the wet paper peelability in the case of the wet paper conveyer, will change, and it becomes difficult to use the papermaking belt for a long period of time. However, the wet paper-carrying surface 111 of the wet paper conveyer 1 of the present embodiment has protrusions of a prescribed size or more and cracks of a certain degree or less, thereby suppressing the peeling of the resin. Thus, the wet paper-carrying surface 111 of the wet paper conveyer 1 suppresses changes in the wet paper adhesiveness and the wet paper peelability.

[0147] Although the present application has been described in detail based on the preferred embodiments, the present application is not limited thereto, and each structure can be replaced with any structure capable of exerting similar functions, and any structure can be added.

[0148] Also, in the above description, the papermaking belt is described taking the wet paper conveyer as an example, but the present application is not limited thereto. For example, the papermaking belt of the present application can be a shoe press belt or another papermaking belt. Also, for example, the papermaking belt of the present application can be manufactured without using an organic solvent having a boiling point of 100°C or more at 1 atm, as long as it has protrusions of a prescribed size or more and cracks of a certain degree or less as described above.

[0149] Example

[0150] The present application will be described more specifically below by way of examples, but the present application is not limited to these examples.

[0151] 1. Manufacture of wet paper conveying belt

[0152] First, the wet paper conveying belts of Examples 1 to 4 and Comparative Examples 1 and 2 were manufactured according to the following configurations.

[0153] Reinforcing fiber base material

[0154] The reinforcing fiber base material of the wet paper conveying belts of Examples 1 to 4 and Comparative Examples 1 and 2 was used as follows.

[0155] Upper warp yarn: 2000 dtex twisted monofilament composed of polyamide 6

[0156] Lower warp yarn: 2000 dtex twisted monofilament composed of polyamide 6

[0157] Weft yarn: 1400 dtex twisted monofilament composed of polyamide 6

[0158] Weave: 40 upper and lower warp yarns / 5 cm, 40 weft yarns / 5 cm, double warp weave

[0159] Formation of laminate

[0160] The fiber reinforcing base material was placed on two rolls, and then a resin composition constituting the resin layer on each roll side was applied to the outer surface of each reinforcing fiber base material, impregnated and laminated to form a reinforcing fiber base material layer and a resin layer on the roll side. Next, a resin composition for forming a resin layer on the wet paper carrying side was applied to the outer surface of each reinforcing fiber base material layer formed, and a resin layer on the wet paper carrying side was laminated. Drying and cross-linking were performed by heating at 145°C for 24 hours using hot air to obtain a semi-finished product of the wet paper conveying belt, in which the laminate was in the order of the resin layer on the wet paper carrying side, the reinforcing fiber base material layer, and the resin layer on the roll side from the outermost layer. Furthermore, drying and cross-linking of the laminate were performed by heating at 145°C for 24 hours using hot air.

[0161] Further, as the resin composition used for forming each layer of Examples 1 to 4 and Comparative Examples 1 and 2, the resin compositions shown in Tables 1 and 2 were used, respectively. In the tables, the crosslinking agent "MF" is melamine formaldehyde resin ("Resimene (registered trademark) 747", manufactured by INEOS Melamines LLC), and, in each of Examples 1 to 4 and Comparative Examples 1 and 2, as the catalyst, an amine salt of p-toluenesulfonic acid ("BYK-CATALYST 450", manufactured by BYK-Chemie Japan K.K.) was used; as the leveling agent, a nonionic acetylene diol ("Surfynol 104PA", manufactured by Nippon Shokubai Co., Ltd.) was used; as the defoaming agent, a mixture of mineral oil, metal soap, and a polyether-type nonionic surfactant ("Nopco DF-122-NS", manufactured by San Nopco Corporation) was used; as the thickening agent, an acrylic resin emulsion (acrylic resin, "Primal (registered trademark) ASE-60", manufactured by Dow Chemical Japan Co., Ltd.) was used; and, as the aqueous ammonia diluted with water to 15 mass percent, "ammonia water (28%)" (manufactured by Junsei Chemical Co., Ltd.) was used.

[0162] Further, Table 2 shows the compositions of the urethane resin aqueous dispersions PUD1 to PUD5 in Table 1. Further, in the table, "PUD1" is a urethane resin aqueous dispersion ("ETERNACOLL (registered trademark) UW-1005E", manufactured by Ube Industries, Ltd.); "PUD2" is a urethane resin aqueous dispersion ("ETERNACOLL (registered trademark) UW-1005A", manufactured by Ube Industries, Ltd.); "PUD3" is a polyurethane aqueous dispersion ("Bayhydrol (registered trademark) 124", manufactured by Covestro Co.); "PUD4" is a urethane resin aqueous dispersion ("ETERNACOLL (registered trademark) UW-1005D-C1", manufactured by Ube Industries, Ltd.); and "PUD5" is a urethane resin aqueous dispersion ("Hydran (registered trademark) WLS-210", manufactured by DIC Corporation). Further, PU1 to PU5 in the urethane resin aqueous dispersions PUD1 to PUD5 are all urethane resins corresponding to the above products, and are different from each other, but on the other hand, are all considered to contain an aliphatic isocyanate and a polycarbonate-based diol as components.

[0163] Further, in the table, "NEP" is 1-ethyl-2-pyrrolidinone (boiling point at 1 atm 218°C, vapor pressure at 20°C 18 Pa); "MDMPA" is 3-methoxy-N,N-dimethylpropanamide (boiling point at 1 atm 215°C, vapor pressure at 20°C 76 Pa); "NMP" is 1-methyl-2-pyrrolidinone (boiling point at 1 atm 204°C, vapor pressure at 20°C 39 Pa); "DMM" is dipropylene glycol dimethyl ether (boiling point at 1 atm 175°C, vapor pressure at 20°C 80 Pa); and "MEK" is 2-butanone (boiling point at 1 atm 80°C, vapor pressure at 20°C 105000 Pa).

[0164]

[0165]

[0166] Grinding processing, polishing processing

[0167] Grinding paper of #80 to #600 was appropriately set in a grinder, and the wet paper carrying surface of the wet paper conveyor belt (semi-finished product) of Examples 1 to 4 and Comparative Examples 1 and 2 was ground. Further, polishing processing was appropriately performed in order to adjust the surface roughness of the wet paper contact surface, and the arithmetic average roughness of the wet paper carrying surface of the wet paper conveyor belt of each example was set to 3.0 μm. In this way, the wet paper conveyor belt was completed.

[0168] Further, a wet paper conveyor belt having a size of 20.5 m in length and 900 mm in width was manufactured.

[0169] 2. Evaluation of wet paper conveyor belt

[0170] Appearance evaluation

[0171] The wet paper carrying surface of the wet paper conveyor belt of Examples 1 to 4 and Comparative Examples 1 and 2 was subjected to appearance evaluation. Specifically, whether or not a raised portion was present on the wet paper carrying surface of the wet paper conveyor belt and the state thereof were observed using the above-described method. Further, the raised portion having a height of 50 μm or more on the wet paper carrying surface per 1 m 2 of the wet paper carrying surface was counted.

[0172] Next, whether or not a crack was present on the wet paper carrying surface of the wet paper conveyor belt and the state thereof were observed based on the following criteria. Specifically, the wet paper carrying surface of the wet paper conveyor belt was visually observed, and a crack was specified using a digital caliper. Further, the length of each crack was measured, and the crack having a length of 10 mm or more per 1 m 2 of the wet paper carrying surface was counted.

[0173] The above-described results are shown together with the composition of the main components of the resin composition used in each of Examples 1 to 4 and Comparative Examples 1 and 2 in Table 3.

[0174] Resin shedding test

[0175] First, in order to conduct a resin shedding test, test pieces S were cut from the wet paper conveyor belts of Examples 1-4 and Comparative Example 2. The dimensions of the test pieces S were set to be 60 mm wide and 70 mm between the handles. Furthermore, for the test pieces S of Examples 3 and Comparative Example 2, which had raised portions or cracks on the surface, after removing the raised portions, the surface was roughened with sandpaper, and the resin composition constituting the test piece S was recoated and dried to perform repair.

[0176] use Figure 9 The bending fatigue testing apparatus shown was used to conduct resin shedding tests at 20°C and 52% relative humidity. Figure 9 In the bending fatigue testing apparatus shown, the lower grip 71 is connected to the drive shaft 73 via a rigid connecting rod 75. The drive shaft 73 reciprocates, moving in an arc-shaped reciprocating motion as indicated by the arrow on the paper. The distance from the rotation center of the drive shaft 73 to the end of the lower grip 71 on the test piece S side is 168 mm. The test piece S of the wet paper conveyor belt is held in one longitudinal direction by its lower grip 71, and an upper grip 77 is installed in the other longitudinal direction of the test piece S. The weight of the upper grip 77 is set to 400 g. As described above, the test pieces S of the wet paper conveyor belts of Examples 1-4 and Comparative Examples 1 and 2 were arranged on the bending fatigue testing apparatus, and the test piece S was repeatedly reciprocated 20,000 times under the conditions of a moving distance (unidirectional arc-shaped moving distance) of 161 for the lower grip 71 and a reciprocating speed of 162 times / minute. Furthermore, the evaluation was performed based on the following criteria. The results are shown in Table 3.

[0177] A: No resin detachment was observed during the resin detachment test conducted without any repair.

[0178] B: A resin shedding test was conducted during the repair process, and no resin shedding was observed.

[0179] C: A resin shedding test was conducted during the repair process, and resin shedding was observed.

[0180] D: Even if repaired, its surface condition is such that it cannot be used as a wet paper conveyor belt.

[0181]

[0182] As shown in Table 1, the wet paper conveying belts of Examples 1 to 4 suppressed the generation of the raised portions and the cracks on the wet paper carrying surface. Further, the wet paper conveying belts of Examples 1 to 4 did not observe the resin peeling in the resin peeling test. In particular, the wet paper conveying belts of Examples 1 to 3 formed using the organic solvent having a boiling point of 200°C or higher did not observe the raised portions or the cracks, and even if the repair was not performed, the resin peeling was not observed in the resin peeling test.

[0183] On the other hand, in the wet paper conveying belt of Comparative Example 1, a large number of cracks were generated on the wet paper carrying surface. It is presumed that this is because when the liquid such as water is removed from the resin composition, the resin composition shrinks while becoming the resin layer, as a result of which the cracks are generated on the surface. Further, the wet paper conveying belt of Comparative Example 1 generated a large number of cracks, and even if the repair was performed, it was not able to achieve the usable state without the resin peeling test.

[0184] Further, in the wet paper conveying belt of Comparative Example 2, a large number of large raised portions were generated on the wet paper carrying surface. Figure 10 A photograph of the raised portions generated on the wet paper conveying belt of Comparative Example 2 is shown. It is presumed that this is because when the liquid such as water and the organic solvent is removed from the resin composition, the low-boiling-point organic solvent is sharply vaporized and expanded in the resin layer, as a result of which the raised portions are generated. Further, even if the repair was performed on the wet paper conveying belt of Comparative Example 2, a large amount of the resin peeling was observed in the resin peeling test.

[0185] Further, Figure 10 A cross-sectional photograph of the wet paper conveying belt of Comparative Example 2 taken with a microscope is shown. The raised portion site is indicated by an arrow. Figure 10 In the wet paper conveying belt of Comparative Example 2 shown in the photograph, a cavity was generated near the wet paper carrying surface, which resulted in the generation of the large raised portion. It is easily understood that if such a raised portion having a cavity exists, the wet paper carrying surface of the wet paper conveying belt will start to deteriorate from the same site.

[0186] From the above, it is understood that the wet paper conveying belts of Examples 1 to 4 suppress the resin peeling even during use, and suppress the change in the desired properties of the wet paper conveying belt, such as the wet paper adhesiveness and the wet paper peelability.

[0187] Explanation of Reference Numerals

[0188] 1: Wet paper conveying belt

[0189] 11: First resin layer

[0190] 111: Wet paper contact surface

[0191] 13: Fiber-reinforced base material layer

[0192] 131: Fiber-reinforced base material

[0193] 15: second resin layer

[0194] 151: roller contact surface

[0195] 113, 133, 153: resin

Claims

1. A papermaking belt for a paper machine, characterized by, having at least one resin layer containing a resin, the resin layer is formed using a resin composition containing an aqueous dispersion of urethane resin, the resin composition contains an organic solvent having a boiling point of 170°C or higher at 1 atm; The total number of protrusions having a height of 50 μm or more and cracks having a length of 10 mm or more on at least one side surface of the resin layer is 1.0 / m 2 The following.

2. The papermaking belt according to claim 1, characterized by the content of the organic solvent in the resin composition is 5.0 mass% or more and 30 mass% or less.

3. The papermaking belt according to claim 1, wherein the vapor pressure of the organic solvent at 20°C is 200 Pa or less.

4. The papermaking belt according to claim 1, wherein the organic solvent contains one or more selected from the group consisting of 1-methyl-2-pyrrolidinone, 1-ethyl-2-pyrrolidinone, dipropylene glycol dimethyl ether, 3-methoxy-N,N-dimethylpropanamide, and 3-butoxy-N,N-dimethylpropanamide.

5. The papermaking belt according to claim 1, wherein the organic solvent includes an organic solvent having a boiling point of 205°C or higher at 1 atm.

6. The papermaking belt according to claim 5, wherein the organic solvent contains one or more selected from the group consisting of 1-ethyl-2-pyrrolidinone, 3-methoxy-N,N-dimethylpropanamide, and 3-butoxy-N,N-dimethylpropanamide.

7. The papermaking belt according to claim 1, wherein it is a wet paper conveying belt.

8. The papermaking belt according to claim 1, wherein it is a shoe press belt.

9. A manufacturing method of a papermaking belt, characterized by, having a step of forming at least one resin layer using a resin composition containing an aqueous dispersion of urethane resin, the resin composition contains an organic solvent having a boiling point of 170°C or higher at 1 atm; The total number of protrusions having a height of 50 μm or more and cracks having a length of 10 mm or more on at least one side surface of the resin layer is 1.0 / m 2 The following.

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