Papermaking belt and method for manufacturing a papermaking belt

Abstract

[Problem] To provide a belt which is for papermaking and in which a resin in a resin layer is inhibited from coming off during use, and a method for producing the belt for papermaking. [Solution] A belt for papermaking according to an embodiment of the present invention is to be used in a paper-making machine, and has at least one resin layer containing a resin. The total number of bulges having a height of at least 50 μm and cracks having a length of at least 10 mm is at most 1.0 / m2 in at least one surface of the resin layer. A belt for papermaking according to another embodiment of the present invention is to be used in a paper-making machine, and has at least one resin layer containing a resin. The resin layer is formed using a resin composition containing an aqueous urethane resin dispersion. The resin composition contains an organic solvent having a boiling point of 100°C or higher under a pressure of 1 atm.

Description

Technical Field

[0001] The present invention relates to a papermaking belt and a method for manufacturing the same.

Background Art

[0002] A paper-making machine that removes moisture from paper raw materials generally includes a wire part, a press part, and a dryer part. These wire part, press part, and dryer part are arranged in this order along the conveyance direction of the wet paper.

[0003] In each part of such a paper-making machine, various papermaking belts are used for the purpose of conveying wet paper, squeezing wet paper, etc. Examples of such papermaking belts include a wet paper conveyance belt (transfer belt) for conveying and delivering wet paper, a shoe press belt used in a shoe press mechanism, and the like.

[0004] Regarding the delivery of wet paper using a wet paper conveyance belt in the press part, currently, as a paper-making machine, a closed draw paper-making machine that performs the delivery of wet paper in a closed draw is known. In the press part of the closed draw paper-making machine, since the wet paper is conveyed while being placed on a papermaking felt or a wet paper conveyance belt, there is no place where the wet paper runs alone, and the occurrence of paper breakage is prevented. Therefore, the closed draw paper-making machine is excellent in terms of high-speed operation suitability and operation stability.

[0005] On the other hand, in order to appropriately perform the delivery of wet paper in a closed draw paper-making machine, the wet paper conveyance belt is required to have a function of conveying the wet paper in a state where the wet paper is attached (wet paper adhesion), and a function of smoothly detaching the wet paper when delivering the wet paper to the subsequent stage (wet paper peelability). Therefore, in order to realize such contradictory functions, the adhesion of the wet paper carrying surface of the wet paper conveyance 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 contact surface of the resin layer supporting the wet paper has an arithmetic surface roughness within a predetermined range depending on the basis weight of the base paper of the wet paper and the swelling rate of the resin constituting the resin layer with respect to water. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2014-62337 [Patent Document 2] Japanese Patent Publication No. 2014-62338 [Overview of the project] [Problems that the invention aims to solve]

[0008] Incidentally, in paper machines, wet paper is transported at high speed, for example, continuously at speeds of 1000 m / min or more. Under such harsh conditions, the resin that makes up the papermaking belt falls off due to friction and bending fatigue as it travels. When the resin of the papermaking belt falls off in this way, the intended performance of the papermaking belt changes, for example, the wet paper adhesion and wet paper release properties in the case of a wet paper transport belt, making it difficult to use the papermaking belt over a long period of time. Furthermore, in Patent Documents 1 and 2, the adhesion to wet paper and the release properties of wet paper are adjusted by adjusting the surface roughness of the resin layer as well as the swelling rate of the resin in relation to water. However, if the swelling rate of the resin in relation to water is increased, the strength of the resin decreases, and the resin detaches more frequently.

[0009] Therefore, the object of the present invention is to provide a papermaking belt in which the shedding of resin from the resin layer during use is suppressed, and a method for manufacturing the papermaking belt. [Means for solving the problem]

[0010] The inventors diligently studied to achieve the above objectives and found that resin detachment occurs starting from cracks and blisters of a predetermined size or larger on the surface of the papermaking belt, and that resin detachment can be prevented if the number of cracks and blisters per unit area of ​​the surface of the papermaking belt is below a predetermined number. Furthermore, they found that cracks and blisters on the surface of the papermaking belt can be suppressed by using a resin composition containing a urethane resin aqueous dispersion and an organic solvent with a boiling point above a predetermined level when forming the resin layer of the papermaking belt. As a result of further studies, they arrived at the present invention.

[0011] The gist of this invention is as follows: [1] Having at least one resin layer containing resin, On at least one surface of the resin layer, the total number of blisters with a height of 50 μm or more and cracks with a length of 10 mm or more is 1.0 per square meter. 2 The following is a papermaking belt used in a paper machine. [2] The papermaking belt according to [1], wherein the resin layer comprises a water-based urethane resin. [3] Having at least one resin layer containing resin, The aforementioned resin layer is formed using a resin composition containing an aqueous dispersion of urethane resin. The resin composition is a papermaking belt used in a paper machine, comprising an organic solvent with a boiling point of 100°C or higher at 1 atmosphere. [4] The papermaking belt according to [3], wherein the content of the organic solvent in the resin composition is 5.0% by mass or more and 30% by mass or less. [5] The papermaking belt according to [3] or [4], wherein the organic solvent comprises an organic solvent having a boiling point of 170°C or higher at 1 atmosphere. [6] The organic solvent has a vapor pressure of 200 Pa or less at 20°C, and is used for papermaking belts according to any one of [3] to [5]. [7] The papermaking belt according to any one of [3] to [6], wherein the organic solvent comprises one or more selected from the group consisting of 1-methyl-2-pyrrolidone, 1-ethyl-2-pyrrolidone, dipropylene glycol dimethyl ether, 3-methoxy-N,N-dimethylpropanamide, and 3-butoxy-N,N-dimethylpropanamide. [8] The papermaking belt according to any one of [3] to [6], wherein the organic solvent is an organic solvent having a boiling point of 205°C or higher at 1 atmosphere. [9] The papermaking belt according to [8], wherein the organic solvent comprises one or more selected from the group consisting of 1-ethyl-2-pyrrolidone, 3-methoxy-N,N-dimethylpropanamide, and 3-butoxy-N,N-dimethylpropanamide.

[10] A wet paper conveying belt, which is a papermaking belt as described in any one of items [1] to [9].

[11] A shoe press belt, which is a papermaking belt as described in any one of items [1] to [9].

[12] The process includes a step of forming at least one resin layer using a resin composition containing an aqueous dispersion of urethane resin, The resin composition comprises an organic solvent having a boiling point of 100°C or higher at 1 atmosphere, and is a method for manufacturing a belt for papermaking. [Effects of the Invention]

[0012] With the above configuration, it is possible to provide a papermaking belt in which the shedding of resin from the resin layer during use is suppressed, and a method for manufacturing the papermaking belt. [Brief explanation of the drawing]

[0013] [Figure 1] Figure 1 is a machine-cross-sectional view showing a papermaking belt according to one embodiment of the present invention. [Figure 2] Figure 2 is a magnified photograph illustrating the bulging on the wet paper carrying surface of the wet paper conveying belt. [Figure 3] Figure 3 is a schematic cross-sectional view of the first resin layer to illustrate the method for measuring the height of blister formations on the wet paper carrying surface of the wet paper conveying belt. [Figure 4] Figure 4 is a schematic diagram for explaining a preferred embodiment of the method for manufacturing a paper-making belt according to the present invention. [Figure 5] Figure 5 is a schematic diagram for explaining a preferred embodiment of the method for manufacturing a paper-making belt according to the present invention. [Figure 6] Figure 6 is a schematic diagram for explaining a preferred embodiment of the method for manufacturing a paper-making belt according to the present invention. [Figure 7] Figure 7 is a schematic diagram for explaining a preferred embodiment of the method for manufacturing a paper-making belt according to the present invention. [Figure 8] Figure 8 is a schematic diagram for explaining an example of a paper-making machine to which the paper-making belt according to the present invention is applied. [Figure 9] Figure 9 is a schematic diagram of a flexural fatigue testing apparatus used in conducting a resin peeling test. [Figure 10] Figure 10 is a cross-sectional photograph of a bulge formed on the wet paper conveying belt according to Comparative Example 2.

Embodiments for Carrying out the Invention

[0014] Hereinafter, preferred embodiments of the paper-making belt and the method for manufacturing the paper-making belt according to the present invention will be described in detail with reference to the drawings.

[0015] <1. Paper-making Belt> First, the paper-making belt according to a preferred embodiment of the present invention will be described. Figure 1 is a cross-sectional view in the machine cross direction showing an example of the paper-making belt according to a preferred embodiment of the present invention. In the figure, the size of each member is emphasized appropriately for ease of explanation, and the ratio and size of each actual member are not shown here. Here, the above machine cross direction (Cross Machine Direction) is also referred to as "CMD", and the machine direction (Machine Direction) is also referred to as "MD". In addition, in the present embodiment, the wet paper conveying belt will be described as an example of the paper-making belt, but the paper-making belt of the present invention is not limited thereto.

[0016] The wet paper conveying belt (papermaking belt) 1 shown in Figure 1 is used in the press section of a paper machine for conveying and transferring wet paper W. The wet paper conveying belt 1 is an endless, strip-like body; that is, the wet paper conveying belt 1 is an annular belt. The wet paper conveying belt 1 is usually positioned so that its circumferential direction aligns with the machine direction (MD) of the papermaking system.

[0017] The wet paper conveying belt 1 comprises a reinforcing fiber base layer 13, a first resin layer (wet paper supporting side resin layer) 11 provided on one main surface on the outer surface side of the reinforcing fiber base 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 reinforcing fiber base layer 13, and these layers are laminated to form the belt. The first resin layer is the layer that forms the outer surface (outer peripheral surface) of the ring formed by the wet paper conveying belt 1.

[0018] The first resin layer 11 is a layer provided on one main surface of the reinforcing fiber base material layer 13, and is mainly composed of resin 113. The first resin layer 11 has a main surface opposite to the main surface that is joined to the reinforcing fiber base material layer 1 that contacts the wet paper and forms a wet paper supporting surface 111 for supporting the wet paper W. In other words, the wet paper conveying belt 1 can convey the wet paper W by supporting it on the wet paper supporting surface 111 of the first resin layer 11.

[0019] In this embodiment, the total number of blisters with a height of 50 μm or more and cracks with a length of 10 mm or more on the wet paper-supported surface 111 of the first resin layer 11 is 1.0 per square meter. 2 The following is the result. This suppresses the shedding of resin from the first resin layer 11. The inventors have found that the shedding of resin from the first resin layer 11 is often caused by blistering and cracking of a certain size or larger on the wet paper-supported surface 111. Furthermore, the inventors have found that by keeping the number of such blistering and cracking below a certain level, the shedding of resin from the first resin layer 11 can be suppressed.

[0020] The height of the blister on the wet paper carrying surface of the wet paper conveying belt can be measured as follows. Figure 2 is an enlarged photograph illustrating the blister on the wet paper carrying surface of the wet paper conveying belt, and Figure 3 is a schematic cross-sectional diagram of the first resin layer illustrating the method for measuring the height of the blister on the wet paper carrying surface of the wet paper conveying belt. First, the blister is searched for visually and tactilely on the wet paper carrying surface of the wet paper conveying belt as shown in Figure 2. For visual search, a microscope may be used, but visual inspection is the simplest method. Also, relatively tall blisters can be easily identified by touch.

[0021] Next, a cross-sectional observation is performed on the first resin layer of the wet paper conveying belt where the bulge is present, and the height of the bulge is measured. Here, the cross-sectional observation can be performed using an optical microscope such as a digital microscope. For example, in Figure 3, a bubble X is formed in the first resin layer 11 of the wet paper conveying belt 1, and as a result, the resin 113 of the first resin layer 11 is pushed out toward the wet paper supporting surface 111 by the bubble X, resulting in a bulge Y. Here, we assume a straight line α that passes through the region of the wet paper supporting surface 111 other than the bulge Y. Next, we assume a tangent line β that passes through the vertex YP of the bulge Y and is parallel to the straight line α. Then, the distance h between the straight line α and the tangent line β is defined as the height of the bulge.

[0022] Furthermore, cracks can be identified and observed by visually inspecting the wet paper-supported surface 111. The length of the crack is then obtained by measuring the length along the shape of the crack. In this case, the length of the crack is not the straight-line distance between the endpoints, but the length along the shape of the crack, and if the crack is branched, the length of the branched portion of the crack is also included in the length of the crack.

[0023] The total number of blisters with a height of 50 μm or more and cracks with 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 piece / m 2 Below, more precisely, 0.50 pieces / m 2The following is the result. This further suppresses the shedding of resin from the first resin layer 11 of the wet paper conveying belt 1.

[0024] Furthermore, the arithmetic mean roughness Ra of the wet paper supporting surface 111 according to JIS B0601 is not particularly limited, but is preferably 0.3 to 20 μm, more preferably 0.5 to 12.0 μm, and even more preferably 1.0 to 10.0 μm. This ensures that the adhesion and release properties of the wet paper W to the wet paper conveying belt 1 are more reliably excellent.

[0025] Furthermore, in this embodiment, the resin 113 constituting the first resin layer 11 is formed using a resin composition containing a urethane resin aqueous dispersion, and this resin composition contains an organic solvent with a boiling point of 100°C or higher at 1 atmosphere. This suppresses the occurrence of blistering and cracking, and makes it easy to achieve the number of blisters with a height of 50 μm or more and cracks with a length of 10 mm or more as described above. The reason why blistering and cracking can be suppressed in this way is not clear, but it is presumed to be as follows.

[0026] As described above, by including a relatively high-boiling point organic solvent in the resin composition, the organic solvent remains even when water and other low-boiling point solvents in the resin composition evaporate during the formation of the first resin layer 11. This suppresses the rapid increase in viscosity of the resin composition and the formation of a surface coating that inhibits drying. As a result, even if bubbles are generated due to the evaporation of water and other low-boiling point solvents, these bubbles are removed from the resin composition, suppressing the occurrence of blistering. Furthermore, even after the evaporation of water and other low-boiling point solvents, the resin composition maintains its flexibility due to the inclusion of a relatively high-boiling point organic solvent, making it less susceptible to cracking caused by shrinkage of the resin composition due to the evaporation of water and other low-boiling point solvents. It is believed that these phenomena suppress the occurrence of blistering and cracking in the first resin layer 11.

[0027] Furthermore, the resin composition forming the resin 113 includes an aqueous urethane resin dispersion. The aqueous urethane resin dispersion contains an aqueous urethane resin and can form a first resin layer 11 composed of the aqueous urethane resin. Because the wet paper supporting surface 111 of the first resin layer 11 is composed of such an aqueous urethane resin, the wet paper supporting surface 111 becomes hydrophilic, improving the adhesion of the wet paper W to the wet paper supporting surface 111. This makes it easy to control the adhesion and release properties of the wet paper W by adjusting the surface roughness of the wet paper supporting surface 111 to control unevenness. In addition, because the wet paper supporting surface 111 of the first resin layer 11 is hydrophilic, dirt is less likely to adhere to it when the wet paper conveying belt 1 is in use.

[0028] On the other hand, forming a water-based urethane resin requires the use of an aqueous urethane resin dispersion. In this case, as mentioned above, there was a problem that blistering and cracking were likely to occur due to the water, low-boiling point organic solvent, or other solvent or dispersion medium contained in the aqueous urethane resin dispersion. However, in this embodiment, the resin composition contains a relatively high-boiling point organic solvent, thereby suppressing the occurrence of problems caused by the aqueous urethane resin dispersion.

[0029] The resin composition for forming resin 113 will be described below. The resin composition comprises an organic solvent having a boiling point of 100°C or higher at least 1 atmosphere (hereinafter also simply referred to as "high-boiling point solvent") and an aqueous dispersion of urethane resin.

[0030] As a high-boiling point solvent, any known organic solvent with a boiling point of 100°C or higher at 1 atmosphere can be used alone or in combination of two or more. Such high-boiling point solvents are not particularly limited and include, for example, lactam ring-containing solvents such as 1-methyl-2-pyrrolidone (204°C) and 1-ethyl-2-pyrrolidone (218°C), amide solvents such as 3-methoxy-N,N-dimethylpropanamide (215°C), dimethylformamide (153°C), dimethylacetamide (165°C), and 3-butoxy-N,N-dimethylpropanamide (252°C), acid ether ester solvents such as ethyl-3-ethoxypropionate (165°C), and diisobutyl ketone (168°C). Ketone solvents such as isophorone (215°C), sulfoxide solvents such as dimethyl sulfoxide (189°C), glycol solvents such as ethylene glycol (197°C), 1,3-butylene glycol (207°C), glycol ester solvents such as 1,4-butanediol diacetate (230°C), 1,3-butylene glycol diacetate (232°C), diethylene glycol monobutyl ether acetate (247°C), 1,6-hexanediol diacetate (260°C), diethylene glycol mono Ethyl 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 Examples include glycol ether solvents such as ether (241°C), tripropylene glycol-n-butyl ether (276°C), dipropylene glycol phenyl ether (243°C), dipropylene glycol methyl ether acetate (209°C), and diethylene glycol monoethyl ether acetate (218°C); alcohol solvents such as benzyl alcohol (205°C); and ester solvents such as triacetin (259°C), dimethyl glutarate (214°C), and γ-butyrolactone (204°C).The temperatures in parentheses represent the boiling points of each compound at 1 atmosphere.

[0031] Among those described above, the high-boiling point solvent preferably includes one or more selected from the group consisting of lactam ring-containing solvents, amide solvents, and glycol ether solvents; more preferably one or more selected from the group consisting of 1-methyl-2-pyrrolidone, 1-ethyl-2-pyrrolidone, dipropylene glycol dimethyl ether, 3-methoxy-N,N-dimethylpropanamide, and 3-butoxy-N,N-dimethylpropanamide; more preferably one or more selected from the group consisting of 1-ethyl-2-pyrrolidone, dipropylene glycol dimethyl ether, 3-methoxy-N,N-dimethylpropanamide, and 3-butoxy-N,N-dimethylpropanamide; even more preferably one or more selected from the group consisting of 1-ethyl-2-pyrrolidone, 3-methoxy-N,N-dimethylpropanamide, and 3-butoxy-N,N-dimethylpropanamide.

[0032] Furthermore, while the boiling point of each organic solvent constituting the high-boiling-point solvent should be 100°C or higher at 1 atmosphere, the high-boiling-point solvent preferably includes an organic solvent with a boiling point of 170°C or higher, more preferably an organic solvent with a boiling point of 200°C or higher at 1 atmosphere, and even more preferably an organic solvent with a boiling point of 205°C or higher at 1 atmosphere. This makes the above-mentioned effects of the high-boiling-point solvent even more effective, and as a result, the occurrence of blistering and cracking can be further suppressed. Furthermore, the vapor pressure of the high-boiling point solvent at 20°C is not particularly limited, but is, for example, 200 Pa or less, preferably 150 Pa or less, and more preferably 100 Pa or less. This allows the aforementioned effects of the high-boiling point solvent to be obtained more effectively, and as a result, the occurrence of blistering and cracking can be further suppressed.

[0033] Furthermore, the content of the high-boiling point solvent in the resin composition is not particularly limited, but for example, it is 1% by mass or more and 40% by mass or less, preferably 5% by mass or more and 30% by mass or less, and more preferably 7% by mass or more and 25% by mass or less.

[0034] A urethane resin aqueous dispersion is a dispersion in which a water-based urethane resin is dispersed in an aqueous dispersion medium. Examples of urethane resin aqueous dispersions include anionic, nonionic, or cationic self-emulsifying urethane resin aqueous dispersions that are emulsified by self-emulsification, and forced-emulsifying urethane resin aqueous dispersions that are emulsified by adding an emulsifier or the like. Either one may be used, or both may be used in combination. A urethane resin aqueous dispersion contains at least a water-based urethane resin and an aqueous dispersion medium.

[0035] Water-based urethane resins are formed using polyisocyanate compounds, polyols, and, if necessary, curing agents. Therefore, the polyisocyanate compounds, polyols, and curing agents that constitute urethane resins will be described below.

[0036] Examples of polyisocyanate compounds include aromatic polyisocyanate compounds and aliphatic polyisocyanate compounds, which can be used individually or in combination of two or more. Examples of aromatic polyisocyanate compounds include 2,4-trylene-diisocyanate (2,4-TDI), 2,6-trylene-diisocyanate (2,6-TDI), 4,4'-methylenebis(phenylisocyanate) (MDI), p-phenylene-diisocyanate (PPDI), dimethylbiphenyl diisocyanate (TODI), naphthalene-1,5-diisocyanate (NDI), 4,4-dibenzyl diisocyanate (DBDI), xylylene diisocyanate (XDI), tetramethylxylylene-diisocyanate (TMXDI), and polymethylene polyphenyl polyisocyanate (polymeric MDI). The aliphatic polyisocyanate compounds are not particularly limited, but examples include linear aliphatic polyisocyanates such as 1,6-hexamethylene diisocyanate (HDI) and 1,5-pentamethylene diisocyanate, and alicyclic polyisocyanates such as 1-isocyanate-3-isocyanate-methyl-3,5,5-trimethylcyclohexane (IPDI), dicyclohexylmethane-4,4'-diisocyanate (H12MDI), 1,3-cyclohexyl diisocyanate, 1,4-cyclohexyl diisocyanate (CHDI), and 1,3-bis-(isocyanate-methyl)cyclohexane and 1,4-bis-(isocyanate-methyl)cyclohexane (H6XDI). One of these can be used alone or in combination of two or more.

[0037] Water-based urethane resins generally contain aliphatic polyisocyanate compounds. Among those mentioned above, water-based urethane resins preferably contain one or more selected from the group consisting of 1-isocyanate-3-isocyanatemethyl-3,5,5-trimethylcyclohexane (IPDI), dicyclohexylmethane-4,4'-diisocyanate (H12MDI), and 1,6-hexamethylene diisocyanate (HDI).

[0038] The polyol compound is not particularly limited and includes long-chain polyol compounds such as polycaprolactone polyol, polyester polyols such as polyethylene adipate, polyether polyols such as polyethylene glycol, polyoxypropylene glycol, polyhexamethylene ether glycol, and polytetramethylene ether glycol (PTMG), polycarbonate polyols such as polycarbonate diol, polyether carbonate diol, trimethylolpropane, polybutadiene polyol, perfluoropolyether polyol, and silicone polyols such as silicone diol. One of these can be used alone or in combination of two or more.

[0039] The polycarbonate polyol is not particularly limited, but examples include polycarbonate polyols synthesized from a polycarbonate polyol raw material and a polycarbonate source. The polycarbonate polyol raw material is not particularly limited, but examples include linear or branched alkylene glycols having 2 to 20 carbon atoms, hydroxyl group-containing cyclic hydrocarbons having 3 to 20 carbon atoms, etc., and one of these can be used alone or in combination of two or more. Examples of the linear alkylene glycols include ethylene glycol, propanediol, butanediol, pentanediol, hexanediol, heptanediol, octanediol, nonanediol, decanediol, undecanediol, dodecanediol, etc. Examples of the branched-chain alkylene glycols mentioned above include 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, and 2-methyl-1,8-octanediol. Examples of the hydroxyl-containing cyclic hydrocarbons mentioned above include hydroxyl-containing alicyclic alkanes such as 1,3-cyclohexanediol, 1,4-cyclohexanediol, and 1,4-cyclohexanedimethanol.

[0040] The curing agent having an active hydrogen group is not particularly limited, and one or more compounds selected from the group consisting of polyol compounds and polyamines can be used.

[0041] In addition to the long-chain polyol compounds mentioned above, various aliphatic polyol compounds and various alicyclic or aromatic polyol compounds can be used as polyol compounds that may be included in the curing agent.

[0042] The aliphatic polyol compounds are not particularly limited, and include, for example, 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, Examples include alkylene glycol compounds such as 12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,16-hexadecanediol, 1,18-octadecanediol, 1,20-icosanediol, 2-methyl-1,3-propanediol, neopentyl glycol, 2-butyl-2-ethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, and 2-methyl-1,8-octanediol, as well as glycerin, ditrimethylolpropane, trimethylolpropane (TMP), pentaerythritol, and dihydroxymethylpropionic acid (DHPA).

[0043] The alicyclic polyol compound is not particularly limited and examples include 1,4-cyclohexanedimethanol and hydrogenated bisphenol A. The aromatic polyol compounds are not particularly limited and include, for example, hydroquinone bis-β-hydroxyethyl ether (HQEE), hydroxyphenyl ether resorcinol (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, and the like.

[0044] Examples of polyamines are not particularly limited and include hydrazine, ethylenediamine, 4,4'-methylene-bis-(2-chloroaniline) (MOCA), dimethylthiotoluenediamine (DMTDA), diethyltoluenediamine (DETDA), trimethylene glycol 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, xylylenediamine, phenylenediamine, toluene-2,4-diamine, t-butyltoluenediamine, 1,2-bis(2-aminophenylthioethane), and 2-(2-aminoethylamino)ethanol.

[0045] Furthermore, the isocyanate compound, polyol, and / or curing agent described above may be substituted with one or more hydrophilic groups. That is, the water-based urethane resin may have one or more hydrophilic groups. This facilitates self-dispersion in water, making it easier to obtain an aqueous dispersion of urethane resin. In addition, the presence of hydrophilic groups in the water-based urethane resin improves the hydrophilicity of the wet paper carrying surface 111 of the wet paper conveying belt 1, thereby improving the adhesion of the wet paper. Such hydrophilic groups are not particularly limited, but examples include carboxyl groups, sulfo groups, phosphate groups, hydroxyl groups, phenolic hydroxyl groups, amino groups, etc. One of these hydrophilic groups may be substituted, or two or more may be substituted. Also, two or more compounds may be substituted with hydrophilic groups, and in this case, the substituted hydrophilic groups may be the same or different in these compounds.

[0046] Furthermore, among those mentioned above, carboxyl groups, sulfo groups, phosphate groups, hydroxyl groups, phenolic hydroxyl groups, amino groups, etc., can serve as crosslinking points for the crosslinking agent described later, contributing to the improvement of the water resistance and durability of the first resin layer 11. Therefore, it is preferable that the isocyanate compound, polyol and / or curing agent contain one or more selected from the group consisting of carboxyl groups, sulfo groups, phosphate groups, hydroxyl groups, phenolic hydroxyl groups, and amino groups.

[0047] Furthermore, when using polyols having three or more hydroxyl groups, such as glycerin, ditrimethylolpropane, trimethylolpropane (TMP), and pentaerythritol, or polyols having hydrophilic groups other than hydroxyl groups, such as dihydroxymethylpropionic acid (DHPA), it becomes easier to introduce hydrophilic groups into water-based urethane resins.

[0048] The aqueous dispersion medium mainly contains water and optionally contains an organic solvent. The organic solvent is not particularly limited and includes, for example, alcohol-based solvents such as methanol, ethanol, 1-propanol, isopropyl alcohol, 1-butyl alcohol, 2-butanol, isobutyl alcohol, tert-butyl alcohol, and benzyl alcohol; glycol-based solvents such as methanediol, 1,2-ethanediol (ethylene glycol), 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol (1,3-butylene glycol), 1,4-butanediol, 2,3-butanediol, 2-butene-1,4-diol, 1,4-butanediol, and diethylene glycol; other polyhydric alcohol-based solvents such as 3-methoxy-1,2-propanediol and glycerin; 1,4-butanediol diacetate, 1,3-butylene glycol diacetate, diethylene glycol monobutyl ether acetate, 1,Glycol ester solvents such as 6-hexanediol diacetate, 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 other glycol ether solvents, acetone, methyl ethyl ketone, methyl propyl ketone, methyl isobutyl ketone, diethyl ketone, dipropyl ketone, diisobutyl ketone Ketone solvents such as ton, cyclohexanone, diacetone alcohol, isophorone, etc., 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, etc., 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, etc. Ester solvents, acid ether ester solvents such as ethyl-3-ethoxypropionate, carbonate ester solvents such as dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, halogen solvents such as methylene chloride, trichloroethylene, perchloroethylene, 1-bromopropane, chloroform, carbon tetrachloride, lactam ring-containing solvents such as 2-pyrrolidone, 1-methyl-2-pyrrolidone, 1-ethyl-2-pyrrolidone, 3-methoxy-N,N-dimethylpropanamide, dimethylformamide, dimethylacetamide, 3-butoxy-N,Examples include amide solvents such as N-dimethylpropanamide, sulforane, morpholine, acetonitrile, and propionitrile, which can be used individually or in combination of two or more.

[0049] Furthermore, as listed above, the aqueous dispersion medium may also contain the high-boiling point solvent described above as an organic solvent. In this case, the step of separately adding the high-boiling point solvent to the resin composition can be omitted.

[0050] Furthermore, the urethane resin aqueous dispersion may contain an emulsifier. Any emulsifier can be used individually or in combination of two or more.

[0051] The urethane resin aqueous dispersion described above contains, for example, an aqueous urethane resin in the resin composition at a concentration of 5% to 90% by mass, preferably 10% to 70% by mass, and more preferably 15% to 50% by mass.

[0052] Furthermore, the resin composition may also contain a crosslinking agent. The inclusion of a crosslinking agent in the resin composition crosslinks the water-based urethane resin, contributing to an improvement in the strength of the first resin layer 11. Such crosslinking agents are not particularly limited and include, for example, carbodiimide-based crosslinking agents, melamine-based crosslinking agents, epoxy-based crosslinking agents, isocyanate-based crosslinking agents, and the like.

[0053] The content of the crosslinking agent in the resin composition is not particularly limited, but is, for example, 0.1% by mass or more and 30% by mass or less, preferably 0.5% by mass or more and 20% by mass or less, and more preferably 1.0% by mass or more and 10% by mass or less.

[0054] Furthermore, the resin composition may optionally contain pH adjusters such as ammonia, leveling agents such as nonionic acetylene glycol, defoaming agents such as fragrance oils, metal soaps, and nonionic surfactants, and viscosity modifiers such as acrylic resin emulsions.

[0055] Furthermore, the resin composition may further contain thermosetting resins other than water-based urethane resins, such as urethane resins, epoxy resins, acrylic resins, or thermoplastic resins such as polyamide resins, polyarylate resins, and polyester resins.

[0056] Furthermore, the resin 113 constituting the first resin layer 11 may contain one or more inorganic fillers, such as titanium dioxide, kaolin, clay, talc, diatomaceous earth, calcium carbonate, calcium silicate, magnesium silicate, silica, and mica. In other words, the resin composition may contain the above-mentioned inorganic fillers.

[0057] Furthermore, the composition and type of resin material and inorganic filler in the first resin layer 11 may differ or be the same for each part of the first resin layer 11. Furthermore, it is preferable that the first resin layer 11 has the property of not allowing water to pass through. That is, it is preferable that the first resin layer 11 is water-impermeable.

[0058] The reinforcing fiber substrate layer 13 is composed of a reinforcing fiber substrate 131 and a resin 133. The resin 133 is present in the reinforcing fiber substrate layer 13 so as to fill the gaps between the fibers in the reinforcing fiber substrate 131. That is, a portion of the resin 133 is impregnated into the reinforcing fiber substrate 131, while the reinforcing fiber substrate 131 is embedded in the resin 133.

[0059] The reinforcing fiber base material 131 is not particularly limited, but for example, a woven fabric made by weaving warp and weft threads on a loom is commonly used. Alternatively, a grid-like material made by overlapping warp and weft rows can be used without weaving. The fineness of the fibers constituting the reinforcing fiber base material 131 is not particularly limited, but can be, for example, 300 to 10,000 dtex, preferably 500 to 6,000 dtex. Furthermore, the fineness of the fibers constituting the reinforcing fiber base material 131 may differ depending on the part in which the fibers are used. For example, the fineness of the warp threads and weft threads of the reinforcing fiber base material 131 may differ.

[0060] The reinforcing fiber base material 131 can be made from polyester (polyethylene terephthalate, polybutylene terephthalate, etc.), aliphatic polyamides (polyamide 6, polyamide 11, polyamide 12, polyamide 612, etc.), aromatic polyamides (aramid), polyvinylidene fluoride, polypropylene, polyether ether ketone, polytetrafluoroethylene, polyethylene, wool, cotton, metal, etc., either individually or in combination of two or more.

[0061] The material of resin 133 is not particularly limited, and for example, various resins that can be used for resin 113 of the first resin layer 11 described above can be used individually or in combination of two or more. Alternatively, resin 133 may include thermosetting resins such as urethane resins other than water-based urethane resins, epoxy resins, acrylic resins, or thermoplastic resins such as polyamide resins, polyarylate resins, polyester resins, etc. Resin 133 may be the same as or different from resin 113 constituting the first resin layer 11 in terms of type and composition.

[0062] Furthermore, the composition and type of resin 133 in the reinforcing fiber base material layer 13 may differ or be the same for each part of the reinforcing fiber base material layer 13.

[0063] The second resin layer (roll surface side resin layer) 15 is a layer provided on one main surface of the reinforcing fiber base material layer 13, and is mainly composed of resin 153. The second resin layer 15 has a main surface opposite to the main surface that is joined to the reinforcing fiber base material layer 13, which constitutes a roll contact surface 151 for contacting the roll, which will be described later. When the wet paper conveying belt 1 is in use, the roll contact surface 151 comes into contact with the roll, thereby enabling it to obtain power for conveying the wet paper from the roll.

[0064] The resin 153 constituting the second resin layer 15 can be a combination of one or more resin materials that can be used in the first resin layer 11 or the reinforcing fiber base layer 13 as described above. The resin 153 constituting the second resin layer 15 may 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 layer 13 in terms of type and composition.

[0065] In particular, urethane resin is preferred as the resin 153 constituting the second resin layer 15 from the viewpoint of mechanical properties, wear resistance, and flexibility. Furthermore, the second resin layer 15 may contain one or more inorganic fillers, similar to the first resin layer 11. Furthermore, the composition and type of resin material and inorganic filler in the second resin layer 15 may differ or be the same for each part of the second resin layer 15.

[0066] The dimensions of the wet paper conveying belt 1 described above are not particularly limited and can be set as appropriate according to the application. For example, the width of the wet paper conveying belt 1 is not particularly limited, but can be 700 to 13500 mm, preferably 2500 to 12500 mm. For example, the length (circumference) of the wet paper conveying belt 1 is not particularly limited, but can be 4 to 35 m, preferably 10 to 30 m.

[0067] Furthermore, the thickness of the wet paper conveying belt 1 is not particularly limited, but can be, for example, 1.5 to 7.0 mm, preferably 2.0 to 6.0 mm. Furthermore, the wet paper transport belt 1 may have different thicknesses in each section, or it may be the same thickness in each section.

[0068] The wet paper conveying belt 1 described above can be manufactured, for example, by the method for manufacturing a wet paper conveying belt according to this embodiment, which will be described later.

[0069] In summary, in the wet paper conveying belt 1 according to this embodiment, the total number of blisters with a height of 50 μm or more and cracks with a length of 10 mm or more on the wet paper supporting surface 111 of the first resin layer 11 is 1.0 per meter. 2 The following is the result. This suppresses the shedding of resin from the first resin layer 11. Furthermore, in this embodiment, the first resin layer 11 of the wet paper conveying belt 1 is formed using a resin composition containing a urethane resin aqueous dispersion, and this resin composition contains an organic solvent with a boiling point of 100°C or higher at 1 atmosphere. This suppresses the occurrence of blistering and cracking, and makes it easy to achieve the number of blisters with a height of 50 μm or more and cracks with a length of 10 mm or more as described above.

[0070] As a modification of the wet paper conveying belt 1 described above, an embodiment is provided in which butt fibers are needled into the wet paper carrying side and / or roll side of the reinforcing fiber base material 131, and the butt fibers have a layer impregnated with the resin material described above. As for the material of the butt fibers, one type of material that can be used for the reinforcing fiber base material 131 can be used alone or in combination of two or more types.

[0071] <2. Method for manufacturing papermaking belts> Next, an example of a preferred embodiment of the papermaking belt manufacturing method of the present invention described above will be explained. Figures 4 to 7 are schematic diagrams showing an example of a preferred embodiment of the papermaking belt manufacturing method of the present invention.

[0072] The present invention relates to a method for manufacturing a papermaking belt, comprising the step of forming at least one resin layer using a resin composition containing an aqueous dispersion of urethane resin, wherein the resin composition contains an organic solvent with a boiling point of 100°C or higher at 1 atmosphere. Hereinafter, as an example of a papermaking belt, the wet paper conveying belt 1 described above will be explained as an example. Therefore, the method for manufacturing the wet paper conveying belt 1 of this embodiment comprises the step of forming an annular laminate 1' having a second resin layer (roll-side resin layer) 15 as the innermost layer and a first resin layer (wet paper-supporting side resin layer) 11 as the outermost layer (lamination step).

[0073] In this lamination process, an annular and strip-shaped laminate 1' is formed, having a second resin layer 15 as the innermost layer and a precursor 11' of the first resin layer as the outermost layer. The laminate 1' can be formed by any method, but in this embodiment, first, a reinforcing fiber substrate layer 13 is formed by applying the resin material (resin composition) of the second resin layer 15 to the reinforcing fiber substrate 131 so that the resin material penetrates the reinforcing fiber substrate 131, and at the same time, the second resin layer 15 is formed inside the reinforcing fiber substrate layer 13. Next, the precursor 11' of the wet paper supporting resin layer is formed by applying the resin composition of the wet paper supporting resin layer 11 to the outer surface of the formed reinforcing fiber substrate layer 13.

[0074] Specifically, as shown in Figure 4, an annular and strip-shaped reinforcing fiber base material 131 is placed in contact with two parallel-arranged rolls 21. Next, as shown in Figure 5, a resin composition constituting the second resin layer 15 is applied to the outer surface of the reinforcing fiber substrate 131. The resin composition may be applied by any method, but in this embodiment, it is applied to the reinforcing fiber substrate 131 by discharging the resin composition from the resin discharge port 25 while rotating the reinforcing fiber substrate 131 with a roll 21. At the same time, the applied resin composition is uniformly coated onto the reinforcing fiber substrate 131 using a coater bar 23. The resin composition applied at this time can penetrate the reinforcing fiber substrate 131. Therefore, in this embodiment, it is possible to form not only the resin 133 contained in the reinforcing fiber substrate 131 but also the resin 153 constituting the second resin layer 15, and it is possible to form the reinforcing fiber substrate layer 13 and the second resin layer 15 simultaneously.

[0075] Next, as shown in Figure 6, the resin composition constituting the first resin layer 11 is applied to the outer surface of the formed reinforcing fiber base material layer 13. The resin composition may be applied by any method, but in this embodiment, it is done by rotating the formed reinforcing fiber base material layer 13 and the second resin layer 15 with a roll 21 while discharging the resin composition from a resin discharge port 25 to apply the resin material to the outer surface of the reinforcing fiber base material layer 13. At the same time, the applied resin composition is uniformly coated using a coater bar 23. The resin composition constituting each layer may be applied as a mixture with the inorganic filler described above.

[0076] As described above, in this embodiment, the resin 113 of the first resin layer 11 is formed in this step using the resin composition described above, which contains a high-boiling point solvent. Then, as shown in Figure 6, the resin composition constituting the first resin layer 11 is applied to the outer surface of the reinforcing fiber base material layer 13. This suppresses the occurrence of blistering and cracking when forming the first resin layer 11. That is, because the resin composition contains a relatively high-boiling point organic solvent, the organic solvent remains even when water or other low-boiling point solvents contained in the resin composition volatilize during the formation of the first resin layer 11, suppressing the rapid increase in viscosity of the resin composition and the formation of a surface coating that inhibits drying. As a result, even if bubbles are generated due to the volatilization of water or other low-boiling point solvents, these bubbles are removed from the resin composition, suppressing the occurrence of blistering. Furthermore, even after the water or other low-boiling point solvents evaporate, the resin composition maintains its flexibility due to the inclusion of a relatively high-boiling point organic solvent, making it less likely for cracks to occur due to shrinkage of the resin composition accompanying the volatilization of water or other low-boiling point solvents.

[0077] Next, the applied resin composition is dried and crosslinked. This yields a laminate 1' in which the precursor 11' of the first resin layer, the reinforcing fiber base layer 13, and the second resin layer 15 are laminated in this order from the outer surface. The drying and crosslinking method of the resin material is not particularly limited, but can be carried out by heating, ultraviolet irradiation, etc.

[0078] Furthermore, when drying and crosslinking the resin composition by heating, methods such as far-infrared heaters and hot air can be used. Furthermore, when drying and crosslinking the resin composition by heating, the heating temperature of the resin composition is preferably 60 to 150°C, and more preferably 90 to 140°C. The heating time can be, for example, 0.5 to 30 hours, preferably 1 to 25 hours.

[0079] Next, the surface roughness of the outer surface of the precursor 11' of the wet paper-supporting resin layer is adjusted to form a wet paper-supporting resin layer 11 having a wet paper-supporting surface 111 (roughness adjustment step). This results in a wet paper conveying belt 1 for papermaking, with the wet paper-supporting surface 111 formed thereon.

[0080] The surface roughness of the outer surface can be adjusted, for example, by polishing and / or buffing. Specifically, as shown in Figure 5, this is done by bringing a polishing device 27 or a buffing device (not shown) into contact with the laminate 1' while it is suspended on two rolls 21. This makes it possible to achieve the desired arithmetic mean roughness of the wet paper-supported surface 111. Furthermore, if the wet paper carrying surface 111 of the wet paper conveying belt 1 is in the desired state before polishing or buffing, polishing and / or buffing can be omitted.

[0081] In the above-described method for manufacturing a papermaking belt, the roll-side resin composition was passed through the outer surface of the reinforcing fiber substrate 131 to form a second resin layer 15 on the inner surface (penetration method). However, it is also possible to apply the resin composition constituting the second resin layer 15 to the outer surface of the reinforcing fiber substrate 131, forming the second resin layer 15 laminated with the reinforcing fiber substrate layer 13 on the outer surface, and then inverting it to form a precursor 11' of the first resin layer by applying the resin composition of the first resin layer 11 to the outer surface (the inner surface before inversion) of the reinforcing fiber substrate layer 13 (inversion method).

[0082] Furthermore, as a variation of the above-described method for manufacturing the papermaking belt, there is a method in which a reinforcing fiber base material is used in which butt fibers are needled into the wet paper-carrying side and / or roll side of the reinforcing fiber base material, instead of the above-described reinforcing fiber base material 131. This makes it possible to obtain a wet paper conveying belt (papermaking belt) having a first resin layer and / or a second resin layer in which the above-described butt fiber layer is impregnated with a resin composition.

[0083] <3.Paper machine> Next, an example of a paper machine to which the papermaking belt of the present invention is applied will be described. Figure 8 is a schematic diagram illustrating an example of a paper machine to which the papermaking belt of the present invention is applied. The paper machine shown in Figure 8 is equipped with a wire part 30, a press part 40, and a dryer part 50. In the figure, the wet paper W, indicated by the dashed line, is conveyed in the order of wire part 30 to press part 40 and then to dryer part 50, and during the conveying process, it is dewatered, squeezed, and dried to become paper. Furthermore, the following paper machine is a so-called closed-draw paper machine. Therefore, in the transfer of the wet paper W to the press part 40, it is carried on either the press felt 41, 42, 43 or the wet paper conveying belt 1, and there is no place where the wet paper W travels alone.

[0084] The wire part 30 holds the pulp slurry on the wire 31 and dewaters it to form a sheet of wet paper W. The wire part 30 has a known configuration, so a description of its main parts will be omitted. The wet paper W dewatered in the wire part 30 is conveyed by the wire 31, which is supported by the guide roll 33, and transferred to the press felt 41 of the press part 40.

[0085] The press section 40 consists of a roll press section 40A and a shoe press section 40B. The roll press section 40A mainly consists of press felts 41 and 42, press rolls 44A and 44B, suction rolls 45A and 45B, and a guide roll 48.

[0086] The press felts 41 and 42 are endless strip-shaped bodies that carry and transport the wet paper W. The press felts 41 and 42 are arranged to pass between the press rolls 44A and 44B and are supported by multiple guide rolls 48 and suction rolls 45A and 45B. The suction roll 45A is positioned so that the press felt 41 supported on the front side in the transport direction (flow direction) of the wet paper W is in contact with the wire 31. The wet paper W is transferred from the wire 31 to the press felt 41 by the suction roll 45A as it is sucked up.

[0087] Press rolls 44A and 44B constitute the roll press mechanism 44 and press the wet paper W together with press felts 41 and 42 to drain the water from the wet paper W. Suction roll 45B is positioned at the far end in the conveying direction (flow direction) of the wet paper W to support the press felt 42 and sucks up the wet paper W carried on the press felts 41 and 42, separating it from the press felt 41 and leaving it only on the press felt 42.

[0088] The shoe press section 40B mainly consists of a wet paper conveying belt 1, a press felt 43, a shoe press mechanism 46, a suction roll 47, and a guide roll 48. The wet paper conveying belt 1 is as described above. The press felt 43 is an endless strip that carries and conveys the wet paper W. The wet paper conveying belt 1 and the press felt 43 are arranged to pass through the shoe press mechanism 46 and are supported by a plurality of guide rolls 48 and suction rolls 47.

[0089] The suction roll 47 is positioned so that the supporting press felt 43 is in contact with the press felt 42 on the front side in the conveying direction (flow direction) of the wet paper W. The wet paper W is then transferred from the press felt 42 to the press felt 43 by the suction roll 47.

[0090] The shoe press mechanism 46 includes 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 together with the press roll 46A via the shoe press belt 46C, it compresses the wet paper W carried on the wet paper conveying belt 1 and the press felt 43. Here, the wet paper W carried on the press felt 43 and transported to the shoe press mechanism 46 is configured to be carried on the wet paper conveying belt 1 after passing through the shoe press mechanism 46.

[0091] In the dryer part 50, the wet paper W is dried. The dryer part 50 has a known configuration, and a description of its main parts will be omitted. The dryer fabric 53 of the dryer part 50 is supported by a suction roll 51 and contacts the wet paper conveying belt 1. The wet paper W is then transferred from the wet paper conveying belt 1 to the dryer fabric 53 by suction of the wet paper W by the suction roll 51.

[0092] Here, we will explain the movement of the wet paper W in the paper machine described above. Since the wet paper W is naturally a continuous structure, we will explain the movement of a portion of the wet paper W. First, the wet paper W passes sequentially through the wire 31 of the wire part 30, the press felt 41 of the press part 40, and the roll press mechanism 44, and is passed from the press felt 42 to the press felt 43. Then, the press felt 43 transports it 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 transport belt 1, and is pressed by the shoe 46B via the shoe press belt 46C and the press roll 46A.

[0093] In this configuration, the press felt 43 has high water permeability, while the wet paper transport belt 1 has very low water permeability. Therefore, in the shoe press mechanism 46, moisture from the wet paper W is transferred to the press felt 43. Immediately after exiting the shoe press mechanism 46, the pressure is rapidly released, causing the volume of the press felt 43, wet paper W, and wet paper conveyor belt 1 to expand. Due to this expansion and the capillary action of the pulp fibers that make up the wet paper W, some of the moisture in the press felt 43 migrates to the wet paper W, resulting in a phenomenon known as re-wetting.

[0094] However, as mentioned above, the wet paper conveying belt 1 is constructed to have very low water permeability, so it does not retain moisture inside. Therefore, re-wetting hardly occurs from the wet paper conveying belt 1, and the wet paper conveying belt 1 contributes to improving the dewatering efficiency of the wet paper. The wet paper W that has left the shoe press mechanism 46 is conveyed by the wet paper conveying belt 1. The wet paper W is then adsorbed by the suction roll 51 and conveyed to the dryer part 50 by the dryer fabric 53.

[0095] Here, the wet paper conveying belt 1 is required to have two functions: the ability to convey the wet paper W with the wet paper attached to the wet paper carrying surface (outer surface) 111 of the wet paper carrying side resin layer (first resin layer) 11 after it has left the shoe press mechanism 46 (wet paper adhesion); and the ability to smoothly detach the wet paper W when transferring it to the next part (wet paper release). Thus, the wet paper conveying belt 1 is required to have these conflicting functions, and it is necessary to strictly control the adhesion of the wet paper carrying surface 111 of the wet paper conveying belt 1 to the wet paper W.

[0096] However, when using conventional wet paper conveying belts, the resin that makes up the belt falls off due to friction and bending fatigue as it runs. When the resin of the papermaking belt falls off in this way, the intended performance of the papermaking belt, for example, the wet paper adhesion and wet paper release properties in the case of a wet paper conveying belt, changes, making it difficult to use the papermaking belt over a long period of time. However, in this embodiment, the wet paper carrying surface 111 of the wet paper conveying belt 1 has a limit on the amount of blistering and cracking above a predetermined size, thereby suppressing the shedding of resin. As a result, the wet paper carrying surface 111 of the wet paper conveying belt 1 is protected from changes in wet paper adhesion and wet paper release properties.

[0097] Although the present invention has been described in detail above based on preferred embodiments, the present invention is not limited thereto, and each component can be replaced with any component that can perform a similar function, or any component can be added.

[0098] Furthermore, although the above description used a wet paper conveying belt as an example of a papermaking belt, the present invention is not limited to this. For example, the papermaking belt of the present invention may be a shoe press belt or any other type of papermaking belt. Also, for example, the papermaking belt of the present invention may be manufactured at 1 atmosphere without using an organic solvent with a boiling point of 100°C or higher, as long as the blistering and cracking exceeding a predetermined size are below a certain level, as described above. [Examples]

[0099] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0100] 1. Manufacturing of wet paper conveying belts First, the wet paper conveying belts of Examples 1-4 and Comparative Examples 1-2 were manufactured using the following configuration. <Reinforced fiber base material> The reinforcing fiber base materials used for the wet paper conveying belts in Examples 1-4 and Comparative Examples 1 and 2 were as follows. Upper warp: 2000 dtex twisted monofilament made of polyamide 6 Lower warp thread: 2000 dtex twisted monofilament made of polyamide 6 Weft: 1400dtex twisted monofilament made of polyamide 6 Structure: Upper and lower warp threads 40 / 5cm, weft threads 40 / 5cm, double warp structure

[0101] <Formation of laminates> The fiber-reinforced substrate was placed on two rolls, and then the resin composition constituting the resin layer on each roll side was applied to the outer surface of each reinforcing fiber substrate, impregnated, and laminated to form the reinforcing fiber substrate layer and the roll side resin layer. Next, the resin composition for forming each wet paper-carrying side resin layer was applied to the outer surface of each formed reinforcing fiber substrate layer, and the wet paper-carrying side resin layer was laminated. Starting from the outermost layer, the laminates consisting of the wet paper-carrying side resin layer, the reinforcing fiber substrate layer, and the roll side resin layer were dried and crosslinked to obtain a semi-finished wet paper conveying belt. The drying and crosslinking of the laminates were performed by heating with hot air at 145°C for 24 hours.

[0102] The resin compositions used to form each layer in Examples 1-4 and Comparative Examples 1 and 2 are shown in Tables 1 and 2, respectively. In the table, the crosslinking agent "MF" is melamine formaldehyde resin ("Resimene® 747", manufactured by INEOS Melamines LLC). In each of Examples 1 to 4 and Comparative Examples 1 and 2, the catalyst used was p-toluenesulfonic acid amine salt ("BYK-CATALYST 450", manufactured by BYK Chemie Japan Co., Ltd.), the leveling agent was nonionic acetylenediol ("Surfinol 104PA", manufactured by Nisshin Chemical Industry Co., Ltd.), the defoaming agent was a mixture of mineral oil, metal soap, and polyether-type nonionic surfactant ("Nopco DF-122-NS", manufactured by Sunnopco Co., Ltd.), and the thickening agent was acrylic resin emulsion (acrylic resin, "Primal® ASE-60", manufactured by Dow Chemical Japan Ltd.) diluted to 15% by mass with water. The ammonia water used was "Ammonia Water (28%)", manufactured by Junsei Chemical Co., Ltd.

[0103] Table 2 shows the compositions of the urethane resin aqueous dispersions PUD1 to PUD5 in Table 1. 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), "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). Furthermore, PU1 to PU5 in the urethane resin aqueous dispersions PUD1 to PUD5 are all urethane resins corresponding to the above-mentioned products, and although they are different from each other, they are all thought to contain aliphatic isocyanates and polycarbonate-based diols as components.

[0104] In the table, "NEP" is 1-ethyl-2-pyrrolidone (boiling point 218°C at 1 atm, vapor pressure 18 Pa at 20°C), "MDMPA" is 3-methoxy-N,N-dimethylpropanamide (boiling point 215°C at 1 atm, vapor pressure 76 Pa at 20°C), "NMP" is 1-methyl-2-pyrrolidone (boiling point 204°C at 1 atm, vapor pressure 39 Pa at 20°C), "DMM" is dipropylene glycol dimethyl ether (boiling point 175°C at 1 atm, vapor pressure 80 Pa at 20°C), and "MEK" is 2-butanone (boiling point 80°C at 1 atm, vapor pressure 105,000 Pa at 20°C).

[0105] [Table 1]

[0106] [Table 2]

[0107] <Polishing, buffing> The wet paper carrying surfaces of the wet paper conveying belts (semi-finished products) in Examples 1-4 and Comparative Examples 1 and 2 were polished using abrasive cloths ranging from #80 to #600, appropriately set in a polishing device. In addition, buffing was performed as appropriate to adjust the surface roughness of the wet paper contact surface, and the arithmetic mean roughness of the wet paper carrying surface of each wet paper conveying belt was set to 3.0 μm. The wet paper conveying belts were thus completed. The dimensions of the construction were set at 20.5m in height and 900mm in width.

[0108] 2. Evaluation of the wet paper conveyor belt <Exterior Evaluation> The wet paper carrying surface of the wet paper conveying belts in Examples 1-4 and Comparative Examples 1 and 2 was visually evaluated. Specifically, the presence and condition of blistering were observed on the wet paper carrying surface of the wet paper conveying belt using the method described above. In addition, the wet paper carrying surface was evaluated over a 1m² area. 2 We counted the number of blisters with a height of 50 μm or more on the surface of the wet paper-supported material.

[0109] Next, the presence and condition of cracks on the wet paper carrying surface of the wet paper conveying belt were observed according to the following criteria. Specifically, cracks were identified using a digital caliper by visually observing the wet paper carrying surface of the wet paper conveying belt. The length of each crack was then measured, and the wet paper carrying surface was measured over a 1m section. 2 We counted the number of cracks that were 10mm or longer per unit area. The results described above, along with the composition of the main components of the resin compositions used in each of Examples 1 to 4 and Comparative Examples 1 and 2, are shown in Table 3.

[0110] <Resin detachment test> First, for the resin shedding test, test pieces S were cut from the wet paper conveying belts of each of Examples 1 to 4 and Comparative Example 2. The dimensions of the test pieces S were 60 mm in width and 70 mm in length between grips. Furthermore, for the test pieces S of Example 3 and Comparative Example 2 that had blistering or cracking on the surface, the blistering was removed, the surface was roughened with sandpaper, and the resin composition constituting the test piece S was reapplied and dried to repair it.

[0111] The resin detachment test was performed using the bending fatigue testing apparatus shown in Figure 9, under conditions of 20°C and 52% relative humidity. In the bending fatigue testing apparatus shown in Figure 9, the lower grip 71 is connected to the drive shaft 73 via a rigid connecting rod 75, and as the drive shaft 73 rotates to reciprocate, the lower grip reciprocates in an arc shape as indicated by the arrow in 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. One end of the test piece S in the longitudinal direction of the wet paper conveying belt was gripped by the lower grip 71, and the upper grip 77 was attached to the other end of the test piece S in the longitudinal direction. The weight of the upper grip 77 was set to 400 g. As described above, test specimens S of the wet paper conveying belts according to Examples 1-4 and Comparative Examples 1 and 2 were placed in the bending fatigue testing apparatus, and the test specimens S were repeatedly moved back and forth 20,000 times under conditions of a travel distance of 161 for the lower grip 71 (one-way arc travel distance) and a reciprocating speed of 162 reciprocations / minute. The results were then evaluated according to the following criteria. The obtained results are shown in Table 3.

[0112] A: A resin detachment test was conducted without any repairs, and no resin detachment was observed. B: After repairs were made and a resin detachment test was conducted, no resin detachment was observed. C: After repairs were made and a resin detachment test was conducted, resin detachment was observed. D: The surface condition was such that it could not be used as a wet paper conveyor belt even after repair.

[0113] [Table 3]

[0114] As shown in Table 1, the wet paper conveying belts according to Examples 1 to 4 showed suppressed blistering and cracking of the wet paper supporting surface. Furthermore, no resin detachment was observed in the resin detachment test for the wet paper conveying belts according to Examples 1 to 4. In particular, the wet paper conveying belts according to Examples 1 to 3, which were formed using organic solvents with a boiling point of 200°C or higher, showed no blistering or cracking, and no resin detachment was observed in the resin detachment test even without repair.

[0115] In contrast, the wet paper conveying belt of Comparative Example 1 developed numerous cracks on the surface supporting the wet paper. This is presumed to be because, when removing liquids such as water from the resin composition, the resin composition contracted as it formed a resin layer, resulting in cracks on the surface. Furthermore, the wet paper conveying belt of Comparative Example 1 had numerous cracks, and even after repairs, it was not in a condition to withstand use without even needing to conduct a resin shedding test.

[0116] Furthermore, the wet paper conveying belt according to Comparative Example 2 developed numerous large blisters on the wet paper-supporting surface. Figure 10 shows a photograph of the blisters that occurred in the wet paper conveying belt according to Comparative Example 2. It is presumed that when removing liquids such as water and organic solvents from the resin composition, the low-boiling point organic solvent rapidly vaporized and expanded within the resin layer, resulting in the blisters. In addition, even after repairs, a large amount of resin detached from the wet paper conveying belt according to Comparative Example 2 in the resin detachment test.

[0117] Furthermore, Figure 10 is a cross-sectional photograph of the wet paper conveying belt according to Comparative Example 2, taken with a microscope. As shown in Figure 10, in the wet paper conveying belt according to Comparative Example 2, a void has formed near the wet paper carrying surface, causing a large bulge. It is easy to understand that the presence of such a bulge with a void will cause deterioration of the wet paper carrying surface of the wet paper conveying belt, starting from that point.

[0118] From the above, it can be understood that the wet paper conveying belts according to Examples 1 to 4 suppress resin shedding even during use, and that changes in the intended performance of the wet paper conveying belt, such as wet paper adhesion and wet paper release properties, are suppressed. [Explanation of symbols]

[0119] 1. Wet paper conveying belt 11 First resin layer 111 Wet paper contact surface 13 Fiber-reinforced base material layer 131 Fiber-reinforced base material 15. Second resin layer 151 Roll contact surface 113, 133, 153 resin

Claims

1. Having at least one resin layer containing resin, On at least one surface of the resin layer, the total number of blisters with a height of 50 μm or more and cracks with a length of 10 mm or more is 1.0 per meter. ２ The following is a papermaking belt used in a paper machine.

2. The papermaking belt according to claim 1, wherein the resin layer comprises a water-based urethane resin.

3. Having at least one resin layer containing resin, The aforementioned resin layer is water-impermeable. The aforementioned resin layer is formed using a resin composition containing an aqueous dispersion of urethane resin. The resin composition comprises an organic solvent with a boiling point of 100°C or higher at 1 atmosphere, and is used as a papermaking belt for a paper machine.

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

5. The papermaking belt according to claim 3, wherein the organic solvent includes an organic solvent having a boiling point of 170°C or higher at 1 atmosphere.

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

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

8. The papermaking belt according to claim 3, wherein the organic solvent includes an organic solvent having a boiling point of 205°C or higher at 1 atmosphere.

9. The papermaking belt according to claim 8, wherein the organic solvent comprises one or more selected from the group consisting of 1-ethyl-2-pyrrolidone, 3-methoxy-N,N-dimethylpropanamide, and 3-butoxy-N,N-dimethylpropanamide.

10. A papermaking belt according to any one of claims 1 to 3, which is a wet paper conveying belt.

11. A shoe press belt, the papermaking belt according to any one of claims 1 to 3.

12. The process includes a step of forming at least one resin layer using a resin composition containing an aqueous dispersion of urethane resin, The aforementioned resin layer is water-impermeable. The resin composition comprises an organic solvent having a boiling point of 100°C or higher at 1 atmosphere, and is a method for manufacturing a belt for papermaking.

Images