Papermaking belt and method for manufacturing papermaking belt

Abstract

To provide a papermaking belt with suppressed changes in characteristics of a resin layer surface during use and a manufacturing method of a papermaking belt.SOLUTION: A papermaking belt for use in a papermaking machine includes at least one resin layer involving a resin, and has a surface roughness of a surface of the resin layer after 20 hours of contact with a metal plate having a surface roughness of 0.10 μm or lower under a pressure of 100±3 Kg / cm2 in a hot water bath of 70±5°C being 40% or over of a surface roughness of the surface of the resin layer before the contact.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] A papermaking machine that removes moisture from paper stock generally includes a wire part, a press part, and a dryer part, which are arranged in this order along the transport direction of the wet paper.

[0003] In each part of such a papermaking machine, various types of papermaking belts are used for the purpose of transporting wet paper, squeezing wet paper, etc. Examples of such papermaking belts include a wet paper transport belt (transfer belt) for transporting and transferring wet paper, and a shoe press belt used in a shoe press mechanism.

[0004] Regarding the transfer of wet paper using a wet paper transport belt in the press part, currently known paper machines are closed draw paper machines that transfer wet paper in a closed draw. In the press part of a closed draw paper machine, the wet paper is transported while being placed on a papermaking felt or a wet paper transport belt, so there is no place where the wet paper runs alone, and the occurrence of paper breaks is prevented. For this reason, closed draw paper machines are excellent in terms of suitability for high-speed operation and operational stability.

[0005] On the other hand, in order to properly transfer the wet web in a closed draw paper machine, the wet web transfer belt is required to have the function of transporting the wet web with it attached (wet web adhesion) and the function of smoothly releasing the wet web when transferring it to the subsequent stage (wet web releasability). Therefore, in order to achieve these conflicting functions, the adhesion of the wet web carrying surface of the wet web transfer belt to the wet web is an important factor.

[0006] Patent documents 1 and 2 disclose wet paper transfer belts in which the wet paper contact surface of a resin layer supporting the wet paper has an arithmetic surface roughness within a predetermined range depending on the base paper weight of the wet paper and the swelling rate of the resin constituting the resin layer in water. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2014-62337 A [Patent Document 2] JP 2014-62338 A Summary of the Invention [Problem to be solved by the invention]

[0008] In a papermaking machine, the wet paper web is continuously transported at high speed, for example, at a speed of 1000 m / min or more. In such a harsh environment, the surface properties of a papermaking belt, such as a wet paper web transfer belt, change due to wear as it travels and pressure from a press mechanism. In addition, the papermaking belt becomes dirty with use. As a result, the wet paper web adhesion and wet paper web release properties of the papermaking belt change from the initial ones. In this case, if the wet paper web transfer belt is used for a long period of time, a problem may occur in which the wet paper web is not transferred properly. In conventional papermaking belts, there is room for further improvement in this regard.

[0009] Therefore, an object of the present invention is to provide a papermaking belt in which changes in the properties of the resin layer surface during use are suppressed, and a method for producing said papermaking belt. [Means for solving the problem]

[0010] As a result of intensive research to achieve the above object, the present inventors have focused on the fact that a papermaking belt is used in a wet state in a papermaking machine. The present inventors have found that the change in the surface roughness of the resin layer of the papermaking belt in a wet state is related to the change in the properties of the resin layer surface. Furthermore, the present inventors have found that using polycarbodiimide is effective in maintaining the surface roughness of the resin layer of the papermaking belt in a wet state, and as a result of further research, they have arrived at the present invention.

[0011] The gist of the present invention is as follows. [1] At least one resin layer containing a resin; In a hot water bath at 70±5℃, a metal plate with a surface roughness of 0.10μm or less is subjected to a load of 100±3Kg / cm 2 a surface roughness of the resin layer after the belt is brought into contact with the surface of the resin layer at a pressure of 1000 g for 20 hours is 40% or more of the surface roughness of the resin layer before the belt is brought into contact with the surface of the resin layer. [2] The papermaking belt according to [1], wherein the resin in at least the vicinity of the surface of the resin layer is crosslinked with polycarbodiimide. [3] At least one resin layer containing a resin; A papermaking belt for use in a papermaking machine, wherein the resin in at least the vicinity of the surface of the resin layer is crosslinked with polycarbodiimide. [4] The papermaking belt according to any one of [1] to [3], wherein the surface roughness of the surface of the resin layer in a wet state is 0.3 μm or more and 20 μm or less. [5] The papermaking belt according to any one of [1] to [4], wherein the resin in at least the vicinity of the surface of the resin layer contains an N-acylurea bond and / or an isourea bond. [6] The papermaking belt according to any one of [1] to [5], wherein the resin layer contains a urethane resin. [7] The papermaking belt according to [6], wherein the urethane resin contains a water-based urethane resin. [8] The papermaking belt according to any one of [1] to [7], wherein the surface of the resin layer includes a wet paper web contact surface. [9] The papermaking belt according to any one of [1] to [8], which is a wet paper web transfer belt.

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

[11] A method for manufacturing a semiconductor device comprising the steps of: In the above step, the resin in at least the vicinity of the surface of the resin layer to be formed is crosslinked with polycarbodiimide. Effect of the Invention

[0012] With the above-mentioned configuration, it is possible to provide a papermaking belt in which changes in the properties of the resin layer surface during use are suppressed, and a method for manufacturing the papermaking belt. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a cross-machine direction sectional view showing a papermaking belt according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic diagram for explaining a preferred embodiment of a method for producing a papermaking belt according to the present invention. [Diagram 3] FIG. 3 is a schematic diagram for explaining a preferred embodiment of a method for producing a papermaking belt according to the present invention. [Figure 4] FIG. 4 is a schematic diagram for explaining a preferred embodiment of a method for producing a papermaking belt according to the present invention. [Diagram 5] FIG. 5 is a schematic diagram for explaining a preferred embodiment of a method for producing a papermaking belt according to the present invention. [Figure 6] FIG. 6 is a schematic diagram for explaining an example of a papermaking machine to which the papermaking belt according to the present invention is applied. [Figure 7] FIG. 7 is a schematic diagram for explaining the contact treatment when measuring the roughness retention rate of the resin layer surface. [Figure 8] FIG. 8 is a schematic diagram for explaining an apparatus for evaluating the wet paper web transport performance of a wet paper web transfer belt. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of a papermaking belt and a method for manufacturing a papermaking belt according to the present invention will be described in detail with reference to the drawings.

[0015] <1. Paper-making belts> First, a papermaking belt according to a preferred embodiment of the present invention will be described. FIG. 1 is a cross-machine direction cross-sectional view showing an example of a papermaking belt according to a preferred embodiment of the present invention. In the drawing, the size of each member is appropriately exaggerated for ease of explanation, and the actual ratio and size of each member are not shown. Here, the cross-machine direction is also called "CMD", and the machine direction is also called "MD". In this embodiment, a wet paper web transfer belt is described as an example of a papermaking belt, but the papermaking belt of the present invention is not limited thereto.

[0016] The wet paper web transfer belt (papermaking belt) 1 shown in Fig. 1 is used for transporting and transferring a wet paper web W in the press part of a papermaking machine. The wet paper web transfer belt 1 is an endless belt. In other words, the wet paper web transfer belt 1 is a circular belt. The wet paper web transfer belt 1 is usually arranged so that its circumferential direction is along the machine direction (MD) of the papermaking system.

[0017] The wet paper web transfer belt 1 has a reinforcing fiber substrate layer 13, a first resin layer (wet paper web support side resin layer) 11 provided on one main surface on the outer surface side of the reinforcing fiber substrate 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 substrate layer 13, and is formed by laminating these layers. The first resin layer is a layer that forms the outer surface (outer peripheral surface) of the ring formed by the wet paper web transfer belt 1.

[0018] The first resin layer 11 is a layer provided on one main surface of the reinforcing fiber substrate layer 13 and composed mainly of a resin 113 . The first resin layer 11, on the main surface opposite to the main surface bonded to the reinforcing fiber substrate layer 1, constitutes a wet paper support surface 111 for contacting the wet paper and supporting the wet paper W. That is, the wet paper transfer belt 1 can support the wet paper W on the wet paper support surface 111 of the first resin layer 11 and transport the wet paper W.

[0019] In this embodiment, in a warm water bath at 70°C ±5, a metal plate with a surface roughness of 0.10 μm or less is subjected to a load of 100 ± 3 kg / cm 2 The surface roughness of the wet paper web supporting surface 111 after the wet paper web supporting surface 111 of the first resin layer 11 is contacted at a pressure of 1000 MPa for 20 hours is 40% or more of the surface roughness of the wet paper web supporting surface 111 of the first resin layer 11 before contact. Hereinafter, the ratio of the surface roughness of the wet paper web supporting surface 111 after the wet paper web supporting surface 111 of the first resin layer 11 is contacted to the surface roughness of the wet paper web supporting surface 111 of the first resin layer 11 before contact is referred to as roughness retention. The inventors have found that the roughness retention of the wet paper web supporting surface 111 in a wet state is related to changes in the properties of the wet paper web supporting surface 111, and that if the roughness retention is 40% or more, changes in the properties of the wet paper web supporting surface 111 of the wet paper web transfer belt 1 can be suppressed.

[0020] Specifically, the surface roughness of the wet paper web carrying surface 111 affects the function of transporting the wet paper web with the wet paper web attached (wet paper web adhesion), the function of smoothly releasing the wet paper web when transferring the wet paper web to the subsequent stage (wet paper web releasability), etc. On the other hand, the surface roughness of the wet paper web carrying surface 111 is generally measured immediately after manufacture and before wetting. The inventors of the present invention have found that the surface roughness of the wet paper web carrying surface 111 before wetting cannot be regarded as the same as the surface roughness of the wet paper web carrying surface 111 in a wet state when the wet paper web transfer belt 1 is actually used, and that the surface roughness of the wet paper web carrying surface 111 changes over time during use, and have focused on this fact. Then, they have found that the change in the properties of the wet paper web carrying surface 111 during use, specifically the change in wet paper web adhesion and wet paper web releasability, can be grasped using the roughness retention rate of the wet paper web carrying surface 111 in the above-mentioned wet state as an index. It was also found that by making the roughness retention rate of the wet paper supporting surface 111 in a wet state 40% or more, changes in the wet paper adhesion and wet paper peeling properties of the wet paper transport belt 1 can be suppressed, making it possible to stably transfer the wet paper over a long period of time.

[0021] The roughness retention rate of the wet paper web supporting surface 111 of the wet paper web transfer belt 1 can be obtained as follows. First, the surface roughness (arithmetic mean roughness Ra) of the wet paper web carrying surface 111 of the wet paper web transfer belt 1 before the contact process described below is measured. The surface roughness of the wet paper web carrying surface 111 of the wet paper web transfer belt 1 before the contact process is measured in a wet state. First, a sample of the wet paper web transfer belt 1 is immersed in a thermostatic water bath at 70±5°C for 30 minutes. Next, the surface roughness of the wet paper web carrying surface 111 is measured. The surface roughness may be measured by any method, such as contact measurement using a contact roughness meter or atomic force microscope, or non-contact measurement using a white light interferometer or laser microscope. However, it is preferable to adopt contact measurement. The temperature of the thermostatic water bath may be within ±5°C of 70°C.

[0022] Next, in a hot water bath at 70±5℃, a metal plate with a surface roughness of 0.10μm or less is subjected to a load of 100±3Kg / cm 2The wet paper supporting surface 111 of the first resin layer 11 is brought into contact with the wet paper for 20 hours at a pressure of 1000 MPa. The temperature of the hot water bath may be within ±5° C. of 70° C. The surface roughness of the metal plate may be 0.10 μm or less, and the material of the metal plate is not particularly limited.

[0023] Next, the surface roughness of the wet paper web carrying surface 111 of the wet paper web transfer belt 1 after the contact process is measured. This measurement can be performed in the same manner as the measurement of the surface roughness of the wet paper web carrying surface 111 of the wet paper web transfer belt 1 before the contact process described above. That is, a sample of the wet paper web transfer belt 1 is immersed in a thermostatic water bath at 70±5°C for 30 minutes, and then the surface roughness is measured.

[0024] The roughness retention can be calculated using the following formula: Roughness retention rate (%)=(surface roughness of the wet paper web supporting surface 111 after contact treatment) / (surface roughness of the wet paper web supporting surface 111 before contact treatment)×100

[0025] The roughness retention rate of the wet paper web supporting surface 111 of the wet paper web transfer belt 1 may be 40% or more, but is preferably 50% or more, and more preferably 60% or more. This makes it possible to further suppress changes in the wet paper web adhesion and wet paper web peeling properties of the wet paper web transfer belt 1, and enables stable wet paper web transfer over a longer period of time.

[0026] The arithmetic mean roughness Ra of the wet paper web supporting surface 111 in a wet state 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 even more preferably 1 to 10 μm, which ensures that the above-mentioned adhesion and releasability of the wet paper web W to the wet paper web transfer belt 1 are more excellent.

[0027] The material of the resin 113 constituting the first resin layer 11 may be a thermosetting resin such as a urethane resin, an epoxy resin, or an acrylic resin, or a thermoplastic resin such as a polyamide resin, a polyarylate resin, or a polyester resin, either singly or in combination of two or more kinds, and preferably a urethane resin can be used.

[0028] The urethane resin used for the resin 113 constituting the first resin layer 11 is not particularly limited, but may be, for example, a urethane resin obtained by curing a urethane prepolymer having an isocyanate group at the end obtained by reacting a polyisocyanate compound with a polyol together with a curing agent having an active hydrogen group. In addition, anionic, nonionic, or cationic self-emulsifying or forced emulsifying water-based urethane resins may be used.

[0029] Among the above, it is preferable to use an aqueous urethane resin as the resin 113 constituting the first resin layer 11. The aqueous urethane resin is a resin formed by using an aqueous dispersion of a urethane resin. By forming the wet paper web supporting surface 111 of the first resin layer 11 with such an aqueous urethane resin, the wet paper web supporting surface 111 has hydrophilicity, and the adhesion of the wet paper web W to the wet paper web supporting surface 111 is improved. This makes it easier to control the adhesion and peelability of the wet paper web W by adjusting the surface roughness of the wet paper web supporting surface 111 to control the unevenness. In addition, since the wet paper web supporting surface 111 of the first resin layer 11 has hydrophilicity, dirt is less likely to adhere to the wet paper web transfer belt 1 during use, and changes in the properties of the wet paper web supporting surface 111 of the wet paper web transfer belt 1 are further suppressed.

[0030] In this embodiment, the resin 113 constituting the first resin layer 11 is cross-linked with a cross-linking agent containing polycarbodiimide. In this way, by cross-linking the resin near the wet paper web supporting surface 111 with a cross-linking agent containing polycarbodiimide, the water resistance and durability of the wet paper web supporting surface 111 can be improved, and the roughness retention rate of the wet paper web supporting surface 111 described above can be easily achieved. The urethane resin and the crosslinking agent containing polycarbodiimide used therein will be described in detail below.

[0031] As described above, the urethane resin includes, for example, a urethane resin obtained by curing a urethane prepolymer having an isocyanate group at the end, which is obtained by reacting a water-based urethane resin and / or a polyisocyanate compound with a polyol, together with a curing agent having an active hydrogen group. Note that any urethane resin is formed using a polyisocyanate compound, a polyol, and, if necessary, a curing agent. Therefore, the polyisocyanate compound, polyol, and curing agent that constitute the urethane resin will be described below.

[0032] Examples of the polyisocyanate compound include aromatic polyisocyanate compounds and aliphatic polyisocyanate compounds, and one of these can be used alone or two or more can be used in combination. Examples of the aromatic polyisocyanate compound include 2,4-tolylene diisocyanate (2,4-TDI), 2,6-tolylene diisocyanate (2,6-TDI), 4,4'-methylenebis(phenylisocyanate) (MDI), p-phenylene diisocyanate (PPDI), dimethylbiphenylene diisocyanate (TODI), naphthalene-1,5-diisocyanate (NDI), 4,4-dibenzyl diisocyanate (DBDI), xylylene diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI), polymethylene polyphenyl polyisocyanate (polymeric MDI), etc. The aliphatic polyisocyanate compound is not particularly limited, but examples thereof include chain aliphatic polyisocyanates such as 1,6-hexamethylene diisocyanate (HDI) and 1,5-pentamethylene diisocyanate, and alicyclic polyisocyanates such as 1-isocyanate-3-isocyanatemethyl-3,5,5-trimethylcyclohexane (IPDI), dicyclohexylmethane-4,4'-diisocyanate (H12MDI), 1,3-cyclohexyl diisocyanate, 1,4-cyclohexyl diisocyanate (CHDI), and 1,4-bis-(isocyanatemethyl)cyclohexane (H6XDI). Among these, one type may be used alone, or two or more types may be used in combination.

[0033] In addition, the water-based urethane resin generally contains an aliphatic polyisocyanate compound. Among the above, the urethane resin preferably contains 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).

[0034] The polyol compound is not particularly limited, and examples thereof include long-chain polyol compounds, for example, polyester polyols such as polycaprolactone polyol and 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. Among these, one type can be used alone, or two or more types can be used in combination.

[0035] The polycarbonate polyol is not particularly limited, but may be, for example, a polycarbonate polyol synthesized from a polycarbonate polyol raw material polyol and a polycarbonate source. The polycarbonate polyol raw material polyol is not particularly limited, but may be, for example, a linear or branched alkylene glycol having a carbon number of 2 to 20, or a hydroxyl-containing cyclic hydrocarbon having a carbon number of 2 to 20, and may be used alone or in combination of two or more. The linear alkylene glycol may be, for example, ethylene glycol, propanediol, butanediol, pentanediol, hexanediol, heptanediol, octanediol, nonanediol, decanediol, undecanediol, dodecanediol, etc. Examples of the branched alkylene glycol include 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2-methyl-1,8-octanediol, etc. Examples of the hydroxyl group-containing cyclic hydrocarbon include hydroxyl group-containing alicyclic alkanes such as 1,3-cyclohexanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, etc.

[0036] 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.

[0037] As the polyol compound that can be contained in the curing agent, in addition to the above-mentioned long-chain polyol compounds, various aliphatic polyol compounds and various alicyclic or aromatic polyol compounds can be used.

[0038] The aliphatic polyol compound is not particularly limited, and examples thereof include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,5-hexanediol, 1,6-hexanediol, 2,5-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1, Examples of suitable alkylene glycol compounds include 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).

[0039] The alicyclic polyol compound is not particularly limited, and examples thereof include 1,4-cyclohexanedimethanol, hydrogenated bisphenol A, and the like. The aromatic polyol compound is not particularly limited, and examples thereof include 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, and alkylene oxide adducts of bisphenol S.

[0040] The polyamine is not particularly limited, and examples thereof 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.

[0041] The above-mentioned isocyanate compound, polyol and / or curing agent may be substituted with one or more hydrophilic groups. That is, the urethane resin may have one or more hydrophilic groups. This makes it easy to self-disperse in water, and makes it easy to obtain a water-based urethane resin. In addition, the urethane resin has a hydrophilic group, which improves the hydrophilicity of the wet paper support surface 111 of the wet paper transfer belt 1, and improves the adhesion of the wet paper. Such hydrophilic groups are not particularly limited, but include carboxyl groups, sulfo groups, phosphoric acid groups, hydroxyl groups, phenolic hydroxyl groups, amino groups, and the like. One of these hydrophilic groups may be substituted, or two or more may be substituted. Two or more compounds may be substituted with hydrophilic groups, and in this case, the hydrophilic groups to be substituted may be the same or different in these compounds.

[0042] Among the above, carboxyl groups, sulfo groups, phosphoric acid groups, hydroxyl groups, phenolic hydroxyl groups, amino groups, and the like can serve as crosslinking points for reacting with polycarbodiimide described below, and contribute to improving the roughness retention rate and improving the water resistance and durability of the first resin layer 11. Therefore, the isocyanate compound, polyol, and / or curing agent preferably contain one or more groups selected from the group consisting of carboxyl groups, sulfo groups, phosphoric acid groups, hydroxyl groups, phenolic hydroxyl groups, and amino groups.

[0043] The crosslinking agent crosslinks the polyurethane polymers in the urethane resin, improving the water resistance and durability of the first resin layer 11. In this embodiment, the crosslinking agent includes polycarbodiimide. By crosslinking the polymers in the resin 113 with polycarbodiimide, the water resistance and durability of the wet paper web support surface 111 can be improved, and the roughness retention rate of the wet paper web support surface 111 described above can be easily achieved.

[0044] Polycarbodiimide contains multiple carbodiimide bonds, and can bond to surrounding resins by reacting the carbodiimide bonds with functional groups such as hydroxyl groups, carboxyl groups, etc. The polycarbodiimide may be any polycarbodiimide that contains multiple carbodiimide bonds, and examples of the polycarbodiimide include compounds having a structure as shown in the following formula (1).

[0045] [ka]

[0046] In the above formula (1), R 1 is, independently at each occurrence, a substituted or unsubstituted divalent hydrocarbon group having from 1 to 20 carbon atoms, and n is a number average of 2.0 or greater.

[0047] Such polycarbodiimide represented by formula (1) has many carbodiimide bonds, each of which can react with the functional group of the surrounding resin polymer. The polycarbodiimide having the structure of formula (1) reacts with, for example, a hydroxyl group contained in the resin polymer to form an isourea bond, and the resin polymer and polycarbodiimide are bonded via the isourea bond. The polycarbodiimide having the structure of formula (1) reacts with, for example, a carboxyl group contained in the resin polymer to form an N-acylurea bond, and the resin polymer and polycarbodiimide are bonded via the N-acylurea bond. Therefore, when the polycarbodiimide represented by formula (1) is used, the resin 113 of the first resin layer 11 can be strongly crosslinked, and the water resistance and durability can be sufficiently improved. In addition, the roughness retention rate of the wet paper support surface 111 can be made sufficiently high.

[0048] In the above formula (1), R 1 Specifically, may be a linear, branched or cyclic substituted or unsubstituted alkylene group, a substituted or unsubstituted arylene group, or a combination of two or more of these groups.

[0049] Examples of linear alkylene groups include methylene, ethylene, n-propylene, n-butylene, n-pentylene, n-hexylene, n-heptylene, n-octylene, n-nonylene, n-decylene, n-undecylene, n-dodecylene, n-tridecylene, n-tetradecylene, n-pentadecylene, n-hexadecylene, n-heptadecylene, n-octadecylene, n-nonadecylene, and n-icosylene. Examples of branched alkylene groups include 1-methylpropylene group, 2-methylpropylene group, 1,1-dimethylpropylene group, 1,2-dimethylpropylene group, 1,3-dimethylpropylene group, 2,2-dimethylpropylene group, 1,2,3-trimethylpropylene group, 1,1,2-trimethylpropylene group, 1,2,2-trimethylpropylene group, 1,1,3-trimethylpropylene group, 1-methylbutylene group, 2-methylbutylene group, 1,1-dimethylbutylene group, 1,2-dimethylbutylene group, 1 Examples of the cyclic alkylene group include, but are not limited to, a cyclopentane ring, a cyclohexane ring, a cycloheptane ring, a cyclooctane ring, and an alicyclic group such as a cyclopentane ring, a cyclohexane ring, a cycloheptane ring, or a cyclooctane ring. R 1 may be bonded to the adjacent oxygen atom directly from the alicyclic group or via an alkylene group having 1 to 3 carbon atoms substituted with the alicyclic group. Examples of such cyclic alkylene groups include 1,4-cyclohexanediylbismethylene groups. Examples of arylene groups include monocyclic aromatic groups such as phenylene groups, condensed polycyclic aromatic groups such as naphthylene groups, and non-condensed polycyclic aromatic groups such as biphenylene groups.

[0050] The compound having the structure represented by the above formula (1) can be obtained by polymerizing a polyisocyanate compound. 1 may be a residue obtained by removing an isocyanate group from a polyisocyanate compound. In such a case, R 1 can be, for example, a residue of the above-mentioned polyisocyanate compound, specifically, a residue obtained by removing an isocyanate group from 2,4-tolylene diisocyanate (2,4-TDI), 2,6-tolylene diisocyanate (2,6-TDI), 4,4'-methylenebis(phenylisocyanate) (MDI), 1,6-hexamethylene diisocyanate (HDI), dicyclohexylmethane-4,4'-diisocyanate (H12MDI), 1-isocyanate-3-isocyanatomethyl-3,5,5-trimethylcyclohexane (IPDI), tetramethylxylylene diisocyanate (TMXDI), triisopropylidenephenyl diisocyanate, etc. Specifically, such R 1 Examples of such alkyl ethers include 1-methylbenzene-2,4-diyl, 1-methylbenzene-2,6-diyl, diphenylmethane-4,4'-diyl, 1,6-hexylene, dicyclohexylmethane-4,4'-diyl, 3,5,5-trimethyl-3-methylenecyclohexan-1-yl, benzene-1,3-dimethylene, and triisopropylidenephenyl-diyl.

[0051] R 1 The substituent is not particularly limited, and examples thereof include linear or branched alkyl groups having 1 to 10 carbon atoms, linear or branched hydroxyalkyl groups, aromatic groups, and hydrophilic groups described below. Examples of linear alkyl groups include methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, and n-nonyl groups. Examples of branched alkyl groups include i-propyl, t-butyl, and i-butyl groups. Examples of hydroxyalkyl groups include the linear and branched alkyl groups described above in which one or more hydrogen atoms have been substituted with a hydroxyl group. Examples of aromatic groups include a phenyl group.

[0052] Furthermore, n in the formula may be any number as long as it is 2.0 or more on the number average, and is, for example, 2.0 or more and 20.0 or less, preferably 3.0 or more and 15.0 or less on the number average.

[0053] The terminal structure of the polycarbodiimide compound having the structure represented by the above formula (1) is not particularly limited. For example, when the compound is produced by polymerization of a polyisocyanate compound, the terminal structure may be a residue of the polyisocyanate compound, (-R 1 -N=C=O or -N=C=O), or a urethane bond, a urea bond, an amide bond, or the like derived therefrom.

[0054] The polycarbodiimide compound represented by formula (1) may have a hydrophilic group. Examples of such a hydrophilic group include, but are not limited to, a carboxyl group, a sulfo group, a phosphoric acid group, a hydroxyl group, a phenolic hydroxyl group, and an amino group. One or more of these hydrophilic groups may be substituted. In addition, the above-mentioned R 1 may be partially substituted with a hydrophilic group, or a terminal structure may be partially substituted with a hydrophilic group. Alternatively, the polycarbodiimide compound may have a hydrophobic group. 1 may be partly substituted with a hydrophobic group, or a terminal structure may be partly substituted with a hydrophobic group.

[0055] In the above description, the polycarbodiimide compound has been mainly described as a linear polycarbodiimide compound. However, the polycarbodiimide compound that can be used in the present embodiment is not limited to this, and for example, a polycarbodiimide compound having a branched chain can also be used.

[0056] In addition, the amount of polycarbodiimide used in resin 113 is not particularly limited, but is, for example, 0.3 parts by mass or more and 90 parts by mass or less, preferably 0.6 parts by mass or more and 80 parts by mass or less, and more preferably 1.0 parts by mass or more and 30 parts by mass or less, per 100 parts by mass of resin.

[0057] The crosslinking agent may further include a melamine-based, epoxy-based, isocyanate-based, or other crosslinking agent. The crosslinking agent may be a crosslinking agent composition including a solvent, a dispersant, a surfactant, or the like, and may be a liquid (e.g., a solution, a dispersion, or an emulsion). When the crosslinking agent is in a solution form, the crosslinking agent may be an aqueous solution.

[0058] The above-mentioned crosslinking agent may be used by mixing with materials for forming the urethane resin, such as a urethane prepolymer and a curing agent, or may be used by mixing with a dispersion of an aqueous urethane resin. Alternatively, the crosslinking agent may be used by applying a solution of the crosslinking agent onto the wet paper web support surface 111 after the first resin layer 11 is formed and allowing it to react.

[0059] In addition, the resin 113 constituting the first resin layer 11 may contain one or a combination of two or more inorganic fillers such as titanium oxide, kaolin, clay, talc, diatomaceous earth, calcium carbonate, calcium silicate, magnesium silicate, silica, and mica.

[0060] The composition and type of the resin material and inorganic filler in the first resin layer 11 may be different for each portion in the first resin layer 11 or may be the same. Moreover, the first resin layer 11 preferably has a property of not allowing water to pass therethrough, that is, the first resin layer 11 is preferably water-impermeable.

[0061] 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 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.

[0062] Although there is no particular limitation on the reinforcing fiber substrate 131, for example, a woven fabric made by weaving warp threads and weft threads on a loom or the like is commonly used. Also, a lattice-shaped material made by overlapping rows of warp threads and rows of weft threads without weaving can be used. The fineness of the fibers constituting the reinforcing fiber substrate 131 is not particularly limited, but may be, for example, 300 to 10,000 dtex, and preferably 500 to 6,000 dtex. Furthermore, the fineness of the fibers constituting the reinforcing fiber base 131 may differ depending on the portion in which the fibers are used. For example, the fineness of the warp yarns and the weft yarns of the reinforcing fiber base 131 may differ.

[0063] The material for the reinforcing fiber substrate 131 may be 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., which may be used alone or in combination of two or more.

[0064] The material of the resin 133 is not particularly limited, and for example, the various resins that can be used for the resin 113 of the first resin layer 11 described above can be used alone or in combination of two or more. The resin 133 may be the same as or different from the resin 113 constituting the first resin layer 11 in terms of type and composition.

[0065] The composition and type of the resin 133 in the reinforcing fibrous substrate layer 13 may be different for each portion in the reinforcing fibrous substrate layer 13, or may be the same for each portion.

[0066] The second resin layer (roll surface side resin layer) 15 is a layer provided on one main surface of the reinforcing fiber substrate layer 13, and is mainly composed of a resin 153. The second resin layer 15 constitutes a roll contact surface 151 for contacting a roll described later on the main surface opposite to the main surface bonded to the reinforcing fiber substrate layer 13. When the wet paper web transfer belt 1 is in use, the roll contact surface 151 comes into contact with the roll, so that the wet paper web transfer belt 1 can obtain power for transporting the wet paper web from the roll.

[0067] The resin 153 constituting the second resin layer 15 may be one or a combination of two or more of the above-mentioned resin materials that can be used for the first resin layer 11. 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 substrate layer 13 in terms of type and composition.

[0068] In particular, the resin 153 constituting the second resin layer 15 is preferably a urethane resin from the viewpoints of mechanical properties, abrasion resistance, and flexibility. Similarly to the first resin layer 11, the second resin layer 15 may contain one or more types of inorganic fillers. The composition and type of the resin material and inorganic filler in the second resin layer 15 may be different for each portion in the second resin layer 15 or may be the same.

[0069] The dimensions of the wet paper web transfer belt 1 as described above are not particularly limited, and can be appropriately set according to the application. For example, the width of the wet paper web transfer belt 1 is not particularly limited, but can be set to 700 to 13,500 mm, preferably 2,500 to 12,500 mm. For example, the length (circumferential length) of the wet paper web transfer belt 1 is not particularly limited, but may be 4 to 35 m, and preferably 10 to 30 m.

[0070] The thickness of the wet paper web transfer belt 1 is not particularly limited, but may be, for example, 1.5 to 7.0 mm, and preferably 2.0 to 6.0 mm. Furthermore, the thickness of each portion of the wet paper web transfer belt 1 may be different or the same.

[0071] The above-described wet web transfer belt 1 can be manufactured, for example, by a manufacturing method for a wet web transfer belt according to this embodiment, which will be described later.

[0072] As described above, the wet paper web transfer belt 1 according to this embodiment can suppress changes in wet paper web adhesion and wet paper web peeling properties of the wet paper web transfer belt 1 by making the roughness retention rate of the wet paper web support surface 111 in a wet state 40% or more, and can stably transfer the wet paper web over a long period of time. In other words, the wet paper web transfer belt 1 suppresses changes in the properties of the wet paper web support surface 111 during use.

[0073] As a modified example of the above-mentioned wet paper web transfer belt 1, there may be mentioned an embodiment in which batt fibers are needled on the wet paper web support side and / or the roll side of the reinforcing fiber substrate 131, and the batt fibers have a layer impregnated with the above-mentioned resin material. Note that as the material for the batt fibers, any of the materials usable for the reinforcing fiber substrate 131 may be used alone or in combination of two or more kinds.

[0074] <2. Manufacturing method of papermaking belts> Next, an example of a preferred embodiment of the method for producing the above-mentioned papermaking belt of the present invention will be described. Figures 2 to 5 are schematic diagrams showing an example of a preferred embodiment of the method for producing the papermaking belt of the present invention.

[0075] The method for producing a papermaking belt of the present invention includes a step of forming at least one resin layer, In the above-mentioned step, the resin at least near the surface of the resin layer to be formed is crosslinked with polycarbodiimide. Hereinafter, the above-mentioned wet paper web transfer belt 1 will be described as an example of a papermaking belt. Therefore, the manufacturing method of the wet paper web transfer belt 1 of this embodiment includes a step (lamination step) of forming a ring-shaped laminate 1' having the second resin layer (roll side resin layer) 15 as the innermost layer and the first resin layer (wet paper web carrying side resin layer) 11 as the outermost layer, and in the lamination step, the resin 113 at least near the wet paper web carrying surface 111 of the first resin layer 11 is crosslinked with polycarbodiimide.

[0076] In this lamination step, a ring-shaped and strip-shaped laminate 1' is formed having the second resin layer 15 as the innermost layer and the precursor 11' of the first resin layer as the outermost layer. Any method may be used to form the laminate 1', but in this embodiment, a resin material is first applied to the reinforcing fiber substrate 131 so that the resin material of the second resin layer 15 penetrates the reinforcing fiber substrate 131 to form the reinforcing fiber substrate layer 13, and at the same time, a second resin layer 15 is formed inside the reinforcing fiber substrate layer 13. Next, the resin material of the wet paper web support side resin layer 11 is applied to the outer surface of the formed reinforcing fiber substrate layer 13 to form the precursor 11' of the wet paper web support side resin layer.

[0077] Specifically, as shown in FIG. 2, a ring-shaped, strip-shaped reinforcing fiber base 131 is wound around two rolls 21 arranged in parallel so as to come into contact with the base. Next, as shown in FIG. 3, the resin material of the second resin layer 15 is applied to the outer surface of the reinforcing fiber substrate 131. The application of the resin material may be performed by any method, but in this embodiment, the resin material is applied to the reinforcing fiber substrate 131 by discharging the resin material from the resin discharge port 25 while rotating the reinforcing fiber substrate 131 by the roll 21. In addition, the applied resin material is uniformly applied to the reinforcing fiber substrate 131 using the coater bar 23. The applied resin material 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 at the same time.

[0078] Next, as shown in FIG. 4, the resin material of the first resin layer 11 is applied to the outer surface of the formed reinforcing fiber substrate layer 13. The application of the resin material may be performed by any method, but in this embodiment, the resin material is applied to the outer surface of the reinforcing fiber substrate layer 13 by discharging the resin material from the resin discharge port 25 while rotating the formed reinforcing fiber substrate layer 13 and the second resin layer 15 with a roll 21. At the same time, the applied resin material is uniformly applied using a coater bar 23. The resin material constituting each layer may be applied as a mixture with the above-mentioned inorganic filler.

[0079] As described above, in this embodiment, in this step, the resin 113 in at least the vicinity of the wet paper support surface 111 of the first resin layer 11 is crosslinked by polycarbodiimide. Crosslinking of the resin 113 by polycarbodiimide is preferably performed, for example, by adding a crosslinking agent containing polycarbodiimide to the resin material (resin composition) for forming the first resin layer 11 and performing crosslinking while drying as described below, because it is simple and reliable. For example, when the resin composition for forming the first resin layer 11 contains a water-based urethane resin, the crosslinking agent is mixed into the aqueous dispersion of the water-based urethane resin. Then, as shown in FIG. 4, the resin material of the first resin layer 11 is applied to the outer surface of the reinforcing fiber substrate layer 13.

[0080] Alternatively, a crosslinking agent may be applied onto the precursor 11' of the first resin layer after formation, and crosslinked by drying as described below. For example, this method can be used when it is difficult to mix a crosslinking agent into the resin material for forming the first resin layer 11.

[0081] Next, the applied resin material is dried and crosslinked. This results in a laminate 1' in which the precursor 11' of the first resin layer, the reinforcing fiber substrate layer 13, and the second resin layer 15 are laminated in this order from the outer surface. The method for drying and crosslinking the resin material is not particularly limited, but can be performed by, for example, heating, ultraviolet irradiation, etc.

[0082] When the resin material is dried and crosslinked by heating, for example, a method using a far-infrared heater, hot air, or the like can be used. Furthermore, when the resin material is dried and crosslinked by heating, the heating temperature of the resin material 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, and preferably 1 to 25 hours.

[0083] Next, the surface roughness of the outer surface of the precursor 11' of the wet paper web supporting side resin layer is adjusted to form the wet paper web supporting side resin layer 11 having the wet paper web supporting surface 111 (roughness adjusting step). In this way, a wet paper web transfer belt 1 as a papermaking belt having the wet paper web supporting surface 111 is obtained.

[0084] The surface roughness of the outer surface can be adjusted, for example, by polishing and / or buffing. Specifically, as shown in Fig. 3, this is done by contacting a polishing device 27 or a buffing device (not shown) with the laminate 1' hung between two rolls 21. This allows the arithmetic mean roughness of the wet paper web support surface 111 to be adjusted to the desired value. When the wet paper web supporting surface 111 of the wet paper web transfer belt 1 is in a desired state before the polishing or buffing process, the polishing and / or buffing process can be omitted.

[0085] In the above-mentioned method for manufacturing a papermaking belt, the roll-side resin material is penetrated from the outer surface of the reinforcing fiber substrate 131 to form the second resin layer 15 on the inner surface (penetration method). However, after providing the resin material constituting the second resin layer 15 on the outer surface of the reinforcing fiber substrate 131 to form the second resin layer 15 laminated on the outer surface with the reinforcing fiber substrate layer 13, the precursor 11' of the first resin layer can also be formed by inverting the surface and applying the resin material of the first resin layer 11 to the outer surface of the reinforcing fiber substrate layer 13 (the inner surface before inversion) (inversion method).

[0086] Furthermore, as a variation of the above-mentioned method for manufacturing a papermaking belt, there is a mode in which a reinforcing fiber substrate having batt fibers needled therein is used on the wet paper carrying side and / or roll side of the reinforcing fiber substrate instead of the above-mentioned reinforcing fiber substrate 131. This makes it possible to obtain a wet paper web transfer belt (papermaking belt) having a first resin layer and / or a second resin layer in which the above-mentioned batt fiber layer is impregnated with a resin material.

[0087] <3.Paper machine> Next, an example of a papermaking machine to which the papermaking belt of the present invention is applied will be described. FIG. 6 is a schematic diagram for explaining an example of a papermaking machine to which the papermaking belt of the present invention is applied. The papermaking machine shown in FIG. 6 includes a wire part 30, a press part 40, and a dryer part 50. In the figure, the wet paper W shown by the broken line is conveyed from the wire part 30 to the press part 40 and then to the dryer part 50 in that order, and is dehydrated, squeezed out, and dried during the conveyance to become paper. The following papermaking machine is a so-called closed-draw papermaking machine. Therefore, in the transfer of the wet paper W in the press part 40, there is no place where the wet paper W runs alone, supported by either the press felts 41, 42, 43 or the wet paper transfer belt 1.

[0088] The wire part 30 holds the pulp slurry on the wire 31 and dewaters it to form a sheet-like wet paper web W. The wire part 30 has a known configuration, and a description of the main parts thereof will be omitted. The wet paper web W dewatered in the wire part 30 is transported by the wire 31 supported by guide rolls 33 and delivered to a press felt 41 of the press part 40.

[0089] The press part 40 is composed of a roll press section 40A and a shoe press section 40B. The roll press section 40A is mainly composed of press felts 41, 42, press rolls 44A, 44B, suction rolls 45A, 45B, and a guide roll .

[0090] The press felts 41, 42 are endless bands that support and transport the wet paper web W. The press felts 41, 42 are arranged to pass between the press rolls 44A, 44B, and are supported by a plurality of guide rolls 48 and suction rolls 45A, 45B. The suction roll 45A is arranged so that the press felt 41 supported on the front side in the transport direction (flow direction) of the wet paper web W abuts against the wire 31. The wet paper web W is suctioned by the suction roll 45A, and the wet paper web W is transferred from the wire 31 to the press felt 41.

[0091] The press rolls 44A, 44B constitute a roll press mechanism 44, and together with the press felts 41, 42, press the wet paper W and squeeze out water from the wet paper W. The suction roll 45B is disposed so as to support the press felt 42 at the rear side in the conveying direction (flow direction) of the wet paper W, and sucks up the wet paper W supported by the press felts 41, 42, peeling it off from the press felt 41 and causing it to be supported only by the press felt 42.

[0092] The shoe press section 40B mainly comprises a wet paper web transfer belt 1, a press felt 43, a shoe press mechanism 46, a suction roll 47, and a guide roll 48. The wet paper web transfer belt 1 is as described above. The press felt 43 is an endless belt-like body that supports and transports the wet paper web W. The wet paper web transfer 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 the suction roll 47.

[0093] The suction roll 47 is disposed so that the supporting press felt 43 abuts against the press felt 42 on the front side in the conveying direction (flow direction) of the wet paper web W. The wet paper web W is transferred from the press felt 42 to the press felt 43 by the suction roll 47 sucking the wet paper web W.

[0094] 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 squeezes the wet paper web W carried on the wet paper web transfer belt 1 and the press felt 43 together with the press roll 46A via the shoe press belt 46C. Here, the wet paper web W carried on the press felt 43 and carried into the shoe press mechanism 46 is configured to be carried on the wet paper web transfer belt 1 after passing through the shoe press mechanism 46.

[0095] In the dryer part 50, the wet paper web W is dried. The dryer part 50 has a known configuration, and a description of the main parts thereof will be omitted. The dryer fabric 53 of the dryer part 50 is supported by a suction roll 51 and contacts the wet paper web transfer belt 1. The wet paper web W is then suctioned by the suction roll 51, whereby the wet paper web W is transferred from the wet paper web transfer belt 1 to the dryer fabric 53.

[0096] Here, a description will be given of the running state of the wet paper web W in the papermaking machine. Since the wet paper web W is of course a continuous structure, the movement state of a part of the wet paper web W will be described. First, the wet paper web W passes through the wire 31 of the wire part 30, the press felt 41 of the press part 40, and the roll press mechanism 44 in this order, and is transferred from the press felt 42 to the press felt 43. Then, the wet paper web W is transported to the shoe press mechanism 46 by the press felt 43. In the shoe press mechanism 46, the wet paper web W is sandwiched between the press felt 43 and the wet paper web transfer belt 1, and is pressed by the shoe 46B via the shoe press belt 46C and the press roll 46A.

[0097] At this time, the press felt 43 is configured to have high water permeability, while the wet paper web transfer belt 1 is configured to have very low water permeability. Therefore, in the shoe press mechanism 46, moisture from the wet paper web W is transferred to the press felt 43. Immediately after leaving the shoe press mechanism 46, the pressure is suddenly released, causing the volumes of the press felt 43, the wet paper web W, and the wet paper web transfer belt 1 to expand. Due to this expansion and the capillary phenomenon of the pulp fibers constituting the wet paper web W, a part of the moisture in the press felt 43 transfers to the wet paper web WW, causing a so-called rewetting phenomenon.

[0098] However, as described above, the wet paper web transfer belt 1 is configured to have very low water permeability, so it does not retain moisture inside. Therefore, rewetting hardly occurs in the wet paper web transfer belt 1, and the wet paper web transfer belt 1 contributes to improving the efficiency of squeezing water out of the wet paper web. The wet paper web W that has left the shoe press mechanism 46 is transported by the wet paper web transfer belt 1. The wet paper web W is then adsorbed by the suction roll 51 and transported to the dryer part 50 by the dryer fabric 53.

[0099] Here, the wet paper web transfer belt 1 is required to have the function of transporting the wet paper web W attached to the wet paper web supporting surface (outer peripheral surface) of the wet paper web supporting side resin layer after leaving the shoe press mechanism 46 (wet paper adhesion), and the function of smoothly releasing the wet paper web when transferring the wet paper web W to the next part (wet paper releasability). Thus, the wet paper web transfer belt 1 is required to have conflicting functions, and the adhesion of the wet paper web supporting surface 111 of the wet paper web transfer belt 1 to the wet paper web W must be strictly controlled.

[0100] On the other hand, the wet paper web transfer belt 1 deteriorates due to friction and the press pressure in the shoe press mechanism 46 during long-term continuous running. In addition, contaminant components contained in the wet paper web W, such as sizing agents, fillers, and their reaction products, adhere to and accumulate on the outer surfaces of the wet paper web carrying surface 111 of the wet paper web transfer belt 1. As such, it is not easy for the wet paper web transfer belt 1 to maintain the properties of its wet paper web carrying surface 111 during long-term continuous running. However, in the wet paper web transfer belt 1 of this embodiment, by setting the roughness retention rate of the wet paper web carrying surface 111 to a predetermined level or higher, changes in properties are suppressed, and changes in wet paper web adhesion and wet paper web peelability are suppressed.

[0101] The present invention has been described in detail above based on a preferred embodiment, but the present invention is not limited to this, and each component can be replaced with any component that can perform a similar function, or any component can be added.

[0102] In the above description, the papermaking belt is a wet paper web transfer belt, but the present invention is not limited thereto. For example, the papermaking belt of the present invention may be a shoe press belt or other papermaking belt. In the above description, the wet paper supporting surface 111 of the wet paper transfer belt 1 is described as being cross-linked with polycarbodiimide, but the papermaking belt of the present invention is not limited to this, and does not have to be cross-linked with polycarbodiimide as long as it has a predetermined roughness retention rate. EXAMPLES

[0103] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0104] 1. Manufacturing of wet paper transport belts First, wet paper web transfer belts of Examples 1 to 6 and Comparative Examples 1 and 2 were manufactured according to the following constitution. <Reinforcing fiber substrate> The reinforcing fiber base materials for the wet paper web transfer belts of Examples 1 to 6 and Comparative Examples 1 and 2 were as follows. Upper warp: 2000dtex twisted monofilament made of polyamide 6 Lower warp: 2000dtex 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

[0105] <Formation of Laminate> The fiber reinforced substrate was placed between two rolls, and then the resin material constituting each roll side resin layer was applied to the outer surface of each reinforcing fiber substrate, impregnated, and laminated to form a reinforcing fiber substrate layer and a roll side resin layer. Next, the resin material for each wet paper support side resin layer was applied to the outer surface of each formed reinforcing fiber substrate layer, and the wet paper support side resin layer was laminated. This laminate, which was the wet paper support side resin layer, the reinforcing fiber substrate layer, and the roll side resin layer in this order from the outermost layer, was heated and dried to obtain a semi-finished wet paper transfer belt.

[0106] The resin materials used to construct each layer in Examples 1 to 6 and Comparative Examples 1 and 2 were those shown in Tables 1 and 2, respectively. In the table, "PU1" indicates a polyurethane water dispersion ("ETERNACOLL (registered trademark) UW-1005D-C1" manufactured by Ube Industries, Ltd.), "PU2" indicates a polyurethane water dispersion ("ETERNACOLL (registered trademark) UW-1005E" manufactured by Ube Industries, Ltd.), "PU3" indicates a polyurethane water dispersion ("ETERNACOLL UW-1005A" manufactured by Ube Industries, Ltd.), and "PU4" indicates a polyurethane water dispersion ("Bayhydrol (registered trademark) 124" manufactured by COVESTRO). All of them are urethane resins produced using aliphatic polyisocyanate compounds and polyisocyanate diols. In the table, "CI1" represents a polycarbodiimide aqueous solution ("Carbodilite V-02-L2" manufactured by Nisshinbo Chemical Inc.), "CI2" represents a polycarbodiimide aqueous solution ("Carbodilite SV-02" manufactured by Nisshinbo Chemical Inc.), and "MF" represents a melamine formaldehyde resin ("Resimene (registered trademark) 747" manufactured by INEOS Melamines LLC).

[0107] In addition, the content of each material in the table is the solid content of only the target compound. For example, in the case of a polyurethane water dispersion, the solid content of the polyurethane resin is listed without considering the amount of water or additives in the water dispersion. The remainder of the resin material is basically water, but it also contains leveling agents, defoamers, pH adjusters, thickeners, and organic solvents derived from each material.

[0108] <Polishing and buffing> The wet paper web carrying surfaces of the wet paper web transfer belts (semi-finished products) of Examples 1 to 6 and Comparative Examples 1 and 2 were polished with a polishing device with an appropriate abrasive cloth of #80 to #600. In addition, in order to adjust the surface roughness of the wet paper web contact surface, appropriate buffing was performed, and the arithmetic mean roughness of the wet paper web carrying surface of the wet paper web transfer belt of each example was set to 0.3 to 20 μm. In this way, the wet paper web transfer belt was completed. The manufacturing dimensions were 20.5m in length and 900mm in width.

[0109] 2. Evaluation of wet paper transport belt 2.1. Roughness retention rate, surface roughness The roughness retention was measured for the wet paper web supporting surfaces of the wet paper web transfer belts of Examples 1 to 6 and Comparative Examples 1 and 2. The roughness retention was evaluated as follows. First, the surface roughness (arithmetic mean roughness) of the wet paper carrying surface of the wet paper transfer belt before the contact treatment described below was measured. The surface roughness of the wet paper carrying surface of the wet paper transfer belt before the contact treatment was measured in a wet state. Specifically, a sample of the wet paper transfer belt (disk-shaped with a diameter of 80 mm) was first immersed in a thermostatic water bath at 70°C for 20 hours. Next, the surface roughness of the wet paper carrying surface in the wet state was measured under the following conditions. Note that the surface roughness of the wet paper carrying surface was measured at any five points and averaged.

[0110] Testing machine: SURFCOM 480A (manufactured by Tokyo Seimitsu Co., Ltd.) Measurement conditions: Scanning speed 0.6 m / sec Trial length 8.0mm Cutoff value: 2.5mm

[0111] Next, a contact treatment was carried out on the sample of the wet paper web transfer belt. The contact treatment was carried out using the device shown in Fig. 7. As shown in Fig. 7, a stainless steel vat 63 was placed between press platens 61 and 62, and the metal vat 63 was filled with hot water 66 at 70°C ± 5°C to maintain the temperature. Next, a sample of the wet paper web transfer belt 1 was placed so that the wet paper web carrying surface 111 was in contact with the bottom surface of the metal container 63, and a press treatment was carried out with the press platen 61 from above, via a stainless steel plate 64 and eight sheets of newspaper 65. The pressing conditions were as follows:

[0112] Press pressure: 100±3Kg / cm 2 Press time: 20 hours Press temperature: 70±5℃ Surface roughness of the bottom of the metal container 63: 0.05μm

[0113] Next, the surface roughness of the wet paper web carrying surface of the wet paper web transfer belt after the contact treatment was measured in the same manner as the sample before the contact treatment. The results are shown in Tables 1 and 2.

[0114] 2.2. Evaluation of wet paper transportability The wet web transfer belts of Example 1 and Comparative Example 2 were operated for a long time, and the change in wet web transfer performance was evaluated. Using an evaluation device for wet paper web transfer belts shown in FIG. 8, a wet paper web W was passed through the press nip 12 under the following conditions, and the adhesion and peelability of the wet paper web W to the wet paper web transfer belt were evaluated. The evaluation device shown in FIG. 8 is equipped with a press part 40' equipped with a shoe press section 40B' and a dryer part 50'. The press part 40' has a configuration similar to that of the press part 40 shown in FIG. 6, except that the roll press section 40A is omitted. The press conditions, the configuration of the press felt 43, and the configuration of the wet paper web were as follows. The wet paper web transfer belt 1'' is a wet paper web transfer belt according to Example 1 or Comparative Example 2.

[0115] <Press conditions> Paper speed: 1200m / min Press pressure: 1050kN / m

[0116] <Composition of Press Felt 43> The press felt 43 was prepared by needling batt fibers on both sides of a base fabric to form a middle batt fiber layer (outer periphery) and a back batt fiber layer (inner periphery), and further by needling batt fibers on the outer periphery of the middle batt fiber layer to form a surface batt fiber layer. The structure of the base fabric and the conditions for forming each batt fiber layer are as follows. Three types of felts with different finenesses of surface batt fibers were prepared as the press felt 43. The fineness of the surface batt fibers of each press felt was 3.3 dtex, 6.6 dtex, or 11 dtex.

[0117] (Base fabric: Laminated base fabric) Top fabric base fabric Warp: 1400dtex monofilament made of nylon 6 Weft: 500dtex monofilament made of nylon 6 Weave: Warp threads 50 / 5cm, weft threads 40 / 5cm, 1 / 1 flat weave

[0118] Lower fabric base fabric Warp: 2000dtex twisted monofilament made of nylon 6 Weft: 1400dtex twisted monofilament made of nylon 6 Weave: 40 warp threads / 5cm, 40 weft threads / 5cm, 3 / 1 broken weave

[0119] (Bat fiber needled into base fabric) Surface layer batt fiber: 200g / m of nylon 6 batt fiber 2 Middle layer batt fiber: Nylon 6 20dtex batt fiber 300g / m 2 Back layer batt fiber: Nylon 6 20dtex batt fiber 100g / m 2

[0120] During the evaluation, a shower and a suction box (neither of which are shown) were used to set the moisture content of the felt 43 as follows: Felt moisture content: Felt moisture weight / (Felt moisture weight + Felt basis weight) = Adjusted by 30%

[0121] <Wet paper (handmade sheet)> Pulp: LBKP 100% csf 450mL Basis weight: 60g / m 2 Moisture content of wet paper before pressing: Moisture weight of wet paper before pressing / (Moisture weight of wet paper before pressing + Bone dry weight of wet paper) = Adjusted to 60% (Moisture content adjusted by sandwiching filter paper) Wet paper size: 200mm length x 200mm width

[0122] <Adhesion assessment> Under the above conditions, the adhesion of the wet paper web transfer belt 1'' was evaluated based on whether or not the wet paper web W was in close contact with the wet paper web transfer belt 1'' when the wet paper web W passed through the press nip of the shoe press mechanism 46. When evaluating the adhesion of the wet paper web transfer belt 1'', press felts 43 having surface batt fiber with different finenesses were used and the evaluation was performed according to the following criteria. The adhesion of the wet paper web transfer belt 1'' was evaluated immediately after the wet paper web transfer belt 1'' was laid and after operating the evaluation device for 7 days while replenishing water.

[0123] <Peeling Judgment> The releasability of the wet paper web transfer belt 1'' was evaluated based on whether or not the wet paper web W supported on the wet paper web transfer belt 1'' transferred to the dryer fabric 53. During the evaluation, the vacuum degree of the suction roll 51 was changed to -20 kPa, -30 kPa, and -40 kPa, and the presence or absence of the wet paper web W transferring to the dryer fabric 53 at each vacuum degree was confirmed, and the evaluation was performed according to the following criteria. The releasability of the wet paper web transfer belt 1'' was evaluated immediately after the wet paper web transfer belt 1'' was laid and after operating the evaluation device for 7 days while replenishing water.

[0124] <Evaluation> A: The wet paper web W adhered closely to the wet paper web transfer belt 1' regardless of the fineness of the surface batt fiber of the press felt 43. Also, the wet paper web W transferred to the dryer fabric 53 regardless of the vacuum degree of the suction roll 51. B: When the fineness of the surface batt fiber of the press felt 43 was 6.6 dtex and 11 dtex, the wet paper web W adhered closely to the wet paper web transfer belt 1'', while when the fineness of the surface batt fiber was 3.3 dtex, the wet paper web W did not adhere closely to the wet paper web transfer belt 1''. Also, when the vacuum degree of the suction roll 51 was -30 kPa and -40 kPa, the wet paper web W transferred to the dryer fabric 53, while when the vacuum degree of the suction roll 51 was -20 kPa, the wet paper web W did not transfer to the dryer fabric 53. C: When the fineness of the surface batt fiber of the press felt 43 was 11 dtex, the wet paper web W adhered closely to the wet paper web transfer belt 1', whereas when the fineness of the surface batt fiber was 3.3 dtex or 6.6 dtex, the wet paper web W did not adhere closely to the wet paper web transfer belt 1''. Also, when the vacuum degree of the suction roll 51 was -40 kPa, the wet paper web W transferred to the dryer fabric 53, whereas when the vacuum degree of the suction roll 51 was -20 kPa or -30 kPa, the wet paper web W did not transfer to the dryer fabric 53. D: Regardless of the fineness of the surface batt fiber of the press felt 43, the wet paper web W did not adhere closely to the wet paper web transfer belt 1''.

[0125] In addition, if the above evaluation is A to B, it can be said that the wet web conveying performance is good. In the evaluation after 7 days of operation, the smaller the decrease in the above evaluation is, the smaller the decrease in wet web conveying performance is. If the evaluation is A to B, it can be said that the wet web conveying performance of the wet web transfer belt 1'' is stable during long-term use.

[0126] [Table 1]

[0127] [Table 2]

[0128] As shown in Table 1, the wet paper web transfer belts of Examples 1 to 6 have a roughness retention rate of 40% or more on the wet paper web support surface, suppressing changes in the properties of the wet paper web support surface and allowing stable use over a long period of time.In contrast, the wet paper web transfer belt of Comparative Example 1, which did not use a crosslinking agent, and the wet paper web transfer belt of Comparative Example 2, which used a melamine formaldehyde resin as a crosslinking agent, have a roughness retention rate of less than 40%, not suppressing changes in the properties of the wet paper web support surface and not allowing stable use over a long period of time.

[0129] In fact, when the wet paper web conveying performance of the wet paper web transfer belts of Example 1 and Comparative Example 2 was evaluated, the wet paper web conveying performance of the wet paper web transfer belt of Example 1 was good and did not decrease even after 7 days of continuous operation. On the other hand, the wet paper web conveying performance of the wet paper web transfer belt of Comparative Example 2 decreased even after 7 days of continuous operation, making it difficult to use for a long period of time. [Explanation of symbols]

[0130] 1 Wet paper transport belt 11 First resin layer 111 Wet paper contact surface 13 Fiber reinforced base layer 131 Fiber-reinforced substrate 15 Second resin layer 151 Roll contact surface 113, 133, 153 Resin

Claims

1. At least one resin layer containing a resin, In a hot water bath at 70±5°C, a metal plate with a surface roughness of 0.10 μm or less is subjected to a load of 100±3 kg / cm ２ a surface roughness of the resin layer after the belt is brought into contact with the resin layer at a pressure of 1000 MPa for 20 hours is 40% or more of the surface roughness of the resin layer before the belt is brought into contact with the resin layer.

2. 2. The papermaking belt according to claim 1, wherein a resin at least in the vicinity of a surface of said resin layer is crosslinked with polycarbodiimide.

3. At least one resin layer containing a resin, A papermaking belt for use in a papermaking machine, wherein the resin in at least the vicinity of the surface of the resin layer is crosslinked with polycarbodiimide.

4. 4. The papermaking belt according to claim 1, wherein the surface roughness of the surface of said resin layer in a wet state is 0.3 μm or more and 20 μm or less.

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

6. The papermaking belt according to any one of claims 1 to 5, wherein the resin layer contains a urethane resin.

7. The papermaking belt according to claim 6, wherein the urethane resin includes a water-based urethane resin.

8. The papermaking belt according to any one of claims 1 to 7, wherein a surface of the resin layer includes a wet paper web contact surface.

9. The papermaking belt according to any one of claims 1 to 8, which is a wet paper web transfer belt.

10. The papermaking belt according to any one of claims 1 to 8, which is a shoe press belt.

11. The method includes a step of forming at least one resin layer, In the above step, the resin in at least the vicinity of the surface of the resin layer to be formed is crosslinked with polycarbodiimide.

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