Papermaking belt and method for manufacturing a papermaking belt

Abstract

The present invention provides a papermaking belt that exhibits excellent abrasion resistance and crack resistance simultaneously, as well as a method for manufacturing the papermaking belt. [Solution] The papermaking belt according to the present invention is a papermaking belt used in a paper machine, and has a resin layer containing a polyurethane resin, the polyurethane resin is obtained by reacting a urethane prepolymer having isocyanate groups with a curing agent having active hydrogen groups, the urethane prepolymer is obtained by reacting an isocyanate compound containing 1,5-naphthalene diisocyanate with a polyol compound containing polyoxyalkylene glycol, and the total content of polycarbonate polyol and polyether polycarbonate polyol as constituent components is 5.0% by mass or less.

Description

Technical Field

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

Background Art

[0002] A paper-making machine that removes moisture from the raw material of paper 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 conveying direction of the wet paper.

[0003] The wet paper is conveyed while being successively passed to the papermaking devices provided in each of the wire part, press part, and dryer part, and moisture is removed, and finally it is dried in the dryer part. In each of these parts, papermaking devices corresponding to functions such as dewatering the wet paper (wire part), squeezing the water (press part), and drying (dryer part) are used.

[0004] For example, in each part of the paper-making machine, various paper-making belts and paper-making rolls are used as papermaking devices for the purpose of conveying the wet paper and squeezing the wet paper. Examples of such paper-making belts include a wet paper conveying belt (transfer belt) for conveying and transferring the wet paper, a shoe press belt used in a shoe press mechanism, etc. Examples of paper-making rolls include a press roll used in a roll press mechanism.

[0005] Specifically, the press section typically includes one or more press devices arranged in series along the direction of transport of the wet paper. Each press device is equipped with an endless felt, or a felt formed by connecting ended felts on the paper machine to create an endless felt. Each press device has a roll press mechanism consisting of a pair of opposing rolls, or a shoe press mechanism in which an endless shoe press belt is interposed between the rolls and a concave shoe facing the rolls. As the wet paper is placed on the felt, it moves along the direction of transport of the wet paper, passing through the roll press mechanism or shoe press mechanism, and is pressurized. This causes the felt to continuously absorb the moisture, or the moisture to pass through the felt and be discharged to the outside, thereby squeezing the moisture out of the wet paper.

[0006] A shoe press belt generally consists of a resin with a reinforcing base material embedded within it. This resin forms an outer layer that contacts the felt and an inner layer that contacts the shoe. The shoe press belt then repeatedly travels between a pressurized roll and the shoe.

[0007] Furthermore, regarding the transfer of wet paper using a wet paper conveyor belt in the press section, currently, closed-draw paper machines, which transfer wet paper in a closed-draw manner, are known as paper machines. In the press section of a closed-draw paper machine, wet paper is transported while resting on papermaking felt or a wet paper conveyor belt, so there are no sections where wet paper travels independently, preventing paper breaks. For this reason, closed-draw paper machines are superior in terms of suitability for high-speed operation and operational stability.

[0008] On the other hand, paper machines operate at high speeds, and consequently, the papermaking belts, which also travel at high speeds, are constantly and severely exposed to mechanical loads such as contact with other components of the paper machine, repeated bending, and continuous tension due to high-speed operation. Therefore, these papermaking belts require excellent durability, such as abrasion resistance and bending resistance.

[0009] Patent Document 1 proposes a press sleeve comprising at least one first polymer layer and a second polymer layer, wherein the first polymer layer and the second polymer layer each contain or are manufactured from polyurethane, the polyurethane is formed from a prepolymer and a crosslinking agent, and the prepolymer of the first polymer layer is a reaction product of naphthalene-1,5-diisocyanate as an isocyanate and at least one polyol selected from polycarbonate polyol, polyether polycarbonate polyol or a mixture thereof. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] Japanese Patent Publication No. 2020-526681 [Overview of the Initiative] [Problems that the invention aims to solve]

[0011] Incidentally, abrasion resistance and crack resistance in papermaking belts are important performance characteristics that determine the lifespan of the belt. On the other hand, the inventors' research has shown that abrasion resistance and crack resistance in papermaking belts are conflicting characteristics, but that they can be achieved simultaneously. Conventional papermaking belts have not been able to achieve a high level of both abrasion resistance and crack resistance.

[0012] Therefore, the object of the present invention is to provide a papermaking belt that is simultaneously excellent in wear resistance and crack resistance, and a method for manufacturing the papermaking belt. [Means for solving the problem]

[0013] The inventors, through diligent research to achieve the above objective, discovered that using naphthalene-1,5-diisocyanate as the isocyanate component in a polyurethane resin layer improves abrasion resistance. However, when naphthalene-1,5-diisocyanate is used, the inventors encountered a problem where crack resistance tends to decrease. To further solve this problem, the inventors conducted research and arrived at the present invention.

[0014] The gist of this invention is as follows: [1] A papermaking belt used in a paper machine, Having a resin layer containing polyurethane resin, The polyurethane resin is obtained by reacting a urethane prepolymer having isocyanate groups with a curing agent having active hydrogen groups. The urethane prepolymer is obtained by reacting an isocyanate compound containing 1,5-naphthalene diisocyanate with a polyol compound containing polyoxyalkylene glycol. A papermaking belt in which the total content of polycarbonate polyol and polyether polycarbonate polyol as constituent components is 5.0% by mass or less. [2] The papermaking belt according to [1], wherein the polyoxyalkylene glycol comprises a polyoxyalkylene glycol obtained by polymerizing one or more alkylene glycols having 2 to 8 carbon atoms. [3] The papermaking belt according to [1], wherein the polyoxyalkylene glycol comprises one or more selected from the group consisting of polyethylene glycol, polytrimethylene ether glycol, polyhexamethylene ether glycol, and polytetramethylene ether glycol. [4] The papermaking belt according to [1], wherein the number average molecular weight of the polyoxyalkylene glycol is 500 or more and 3000 or less. [5] forming a ring, The papermaking belt according to [1], wherein the resin layer is an outer peripheral resin layer located on the outer peripheral side. [6] Furthermore, it has an inner circumferential resin layer located on the inner circumferential side and containing a second polyurethane resin, The papermaking belt according to [4], wherein the second polyurethane resin comprises 1,5-naphthalene diisocyanate and / or p-phenylene diisocyanate as constituent components. [7] The second polyurethane resin is obtained by reacting a second urethane prepolymer having isocyanate groups with a second curing agent having active hydrogen groups. The second urethane prepolymer is obtained by reacting an isocyanate compound containing 1,5-naphthalene diisocyanate and / or p-phenylene-diisocyanate with a polyol compound containing polyoxyalkylene glycol, as described in [5], for a papermaking belt. [8] Furthermore, the resin layer and the inner circumferential resin layer are disposed between the resin layer and the reinforcing fiber base layer, and the reinforcing fiber base layer includes a reinforcing fiber base layer and a third polyurethane resin impregnated into the reinforcing fiber base layer, The papermaking belt according to [5], wherein the third polyurethane resin comprises 2,4-trylene-diisocyanate, 2,6-trylene-diisocyanate and / or 1,5-naphthalene diisocyanate as constituent components. [9] forming a ring, The resin layer is an inner circumferential resin layer located on the inner circumferential side, as described in any one of [1] to [4], for a papermaking belt.

[10] The papermaking belt according to [1], wherein the polycarbonate polyol and the polyether polycarbonate polyol are not included as constituent components.

[11] A shoe press belt, the papermaking belt described in [1].

[12] A sleeve roll belt, the papermaking belt described in [1].

[13] A method for manufacturing a papermaking belt used in a paper machine, The process includes a step of forming a resin layer containing polyurethane resin by reacting a urethane prepolymer having isocyanate groups with a curing agent having active hydrogen groups. The urethane prepolymer is obtained by reacting an isocyanate compound containing 1,5-naphthalene diisocyanate with a polyol compound containing polyoxyalkylene glycol. The method for manufacturing a papermaking belt is characterized in that, as a constituent component, the total content of polycarbonate polyol and polyether polycarbonate polyol is 5.0% by mass or less.

Advantages of the Invention

[0015] With the above configuration, it is possible to provide a papermaking belt that is simultaneously excellent in wear resistance and crack resistance, and a method for manufacturing the same.

Brief Description of the Drawings

[0016] [Figure 1] FIG. 1 is a cross-sectional view taken in the machine transverse direction showing a papermaking belt according to an embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view taken in the machine transverse direction showing a papermaking belt according to another embodiment of the present invention. [Figure 3] FIG. 3 is a schematic diagram for explaining a preferred embodiment of the method for manufacturing a papermaking belt according to the present invention. [Figure 4] FIG. 4 is a schematic diagram for explaining a preferred embodiment of the method for manufacturing a papermaking belt according to the present invention. [Figure 5] FIG. 5 is a schematic diagram for explaining a preferred embodiment of the method for manufacturing a papermaking belt according to the present invention. [Figure 6] FIG. 6 is a schematic diagram for explaining the configuration of a flexural fatigue test apparatus used for evaluating crack resistance. [Figure 7] FIG. 7 is a schematic diagram for explaining the configuration of a wear test apparatus used for evaluating wear resistance.

Embodiments for Carrying Out the Invention

[0017] Hereinafter, preferred embodiments of the papermaking belt and the method for manufacturing the papermaking belt according to the present invention will be described in detail with reference to the drawings. In the following description, a shoe press belt will be described as an example of a papermaking belt, but it goes without saying that the papermaking belt according to the present invention is not limited to a shoe press belt.

[0018] <1. Shoe Press Belt> First, a shoe press belt, as an example of a papermaking belt according to a preferred embodiment of the present invention, will be described. Figure 1 is a machine-cross-sectional view showing an example of a papermaking belt (shoe press belt) according to a preferred embodiment of the present invention. Note that in the figure, the size of each component is exaggerated for ease of explanation, and the actual proportions and sizes of each component are not shown. Here, the machine-cross direction (Cross Machine Direction) is also referred to as "CMD," and the machine direction is also referred to as "MD."

[0019] The shoe press belt 1 shown in Figure 1 is used in the press section of a paper machine, more specifically in the shoe press mechanism, to transport wet paper in cooperation with felt and to extract moisture from the wet paper. The shoe press belt 1 is an endless, strip-like body; that is, the shoe press belt 1 is an annular belt. The shoe press belt 1 is usually positioned so that its circumferential direction aligns with the machine direction (MD) of the paper machine.

[0020] The shoe press belt 1 shown in Figure 1 has a reinforcing fiber base layer 10, a first resin layer 20 provided on one main surface on the outer surface side of the reinforcing fiber base layer 10, and a second resin layer 30 provided on the other main surface on the inner surface side of the reinforcing fiber base layer 10, and these layers are laminated to form the belt.

[0021] The reinforcing fiber substrate layer 10 is composed of a reinforcing fiber substrate 11 and a resin 13. The resin 13 is present in the reinforcing fiber substrate layer 10 so as to fill the gaps between the fibers in the reinforcing fiber substrate 11. That is, a portion of the resin 13 is impregnated into the reinforcing fiber substrate 11, while the reinforcing fiber substrate 11 is embedded in the resin 13.

[0022] The reinforcing fiber base material 11 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 without weaving can be used. Or, two or more types of materials, such as woven fabric and grid-like material, may be used in combination. The fineness of the fibers constituting the reinforcing fiber base material 11 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 11 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 11 may differ.

[0023] The reinforcing fiber base material 11 can be made from one or more of the following materials: 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. The resin 13 will be discussed later.

[0024] The first resin layer 20 is a resin layer provided on one main surface on the outer surface side of the reinforcing fiber base material layer 10, and is composed of resin 23. The first resin layer 20 is the felt-side resin layer (outer surface resin layer) that constitutes the outer surface 21, and when the shoe press belt 1 is in use, the wet paper is supported and conveyed on the outer surface 21 via the felt.

[0025] The second resin layer 30 is a resin layer provided on the other main surface located on the inner surface side of the reinforcing fiber base material layer 10, and is composed of resin 33. The second resin layer 30 constitutes the inner circumferential surface 31, and is a shoe-side resin layer (inner circumferential resin layer) that is positioned so as to contact the shoe of the shoe press mechanism (not shown) when the shoe press belt 1 is in use.

[0026] Furthermore, one or more of the reinforcing fiber base layer 10, the first resin layer 20, and the second resin layer 30 are water-impermeable, and the shoe press belt 1 as a whole is water-impermeable. Typically, the reinforcing fiber base layer 10, the first resin layer 20, and the second resin layer 30 are all water-impermeable.

[0027] Here, we will describe the resin 13 in the reinforcing fiber base layer 10 of the shoe press belt 1, the resin 23 in the first resin layer 20, and the resin 33 that constitutes the second resin layer 30.

[0028] In this embodiment, at least one of the reinforcing fiber base layer 10, the first resin layer 20, and the second resin layer 30 of the shoe press belt 1 contains polyurethane resin. The polyurethane resin is obtained by reacting a urethane prepolymer X having isocyanate groups with a curing agent having active hydrogen groups. The urethane prepolymer X is obtained by reacting an isocyanate compound containing 1,5-naphthalene diisocyanate with a polyol compound containing polyoxyalkylene glycol.

[0029] Since the compositions of resins 13, 23, and 33 can be the same, the resin 23 of the first resin layer 20 will be described in detail below as a representative example. Furthermore, the following description will focus on the case where resin 23 includes a polyurethane resin containing the above-mentioned urethane prepolymer X as a constituent component.

[0030] The polyurethane resin constituting the resin 23 contains the above-mentioned urethane prepolymer X as a constituent component. As a result, the first resin layer 20 composed of the resin 23 has excellent abrasion resistance and crack resistance simultaneously.

[0031] To explain in more detail, as mentioned above, the crack resistance and abrasion resistance of papermaking belts are inversely related, and it has been difficult to achieve both simultaneously. The inventors of the present invention have found that abrasion resistance can be improved by including 1,5-naphthalene diisocyanate (NDI) in an isocyanate compound. On the other hand, simply including 1,5-naphthalene diisocyanate in an isocyanate compound leads to a problem in which crack resistance decreases, as has been known from conventional research. Faced with this problem, the inventors of the present invention conducted intensive research and found that by using a prepolymer obtained by reacting 1,5-naphthalene diisocyanate with an isocyanate compound and a polyol compound containing polyoxyalkylene glycol, it is possible to improve the crack resistance of papermaking belts while obtaining the abrasion resistance improvement effect of 1,5-naphthalene diisocyanate.

[0032] The reason why such papermaking belts can achieve both abrasion resistance and crack resistance is not clear, but the inventors believe it to be as follows. First, 1,5-naphthalene diisocyanate has a naphthalene skeleton, and its π electrons allow the planes of the naphthalene skeleton to overlap, enabling high-density overlapping of molecules. Also, when 1,5-naphthalene diisocyanate is used as a component of polyurethane resin, that is, when used as a polymer monomer, it is a component that forms a relatively linear skeleton. Furthermore, 1,5-naphthalene diisocyanate, derived from its naphthalene skeleton, is a component that imparts rigid physical properties to polyurethane resin. Polyurethane resin using such 1,5-naphthalene diisocyanate tends to have relatively high hardness and high tensile strength. Moreover, 1,5-naphthalene diisocyanate functions as a hard segment in the polyurethane resin as a whole, and phase separation from the soft segment is easier as described above. On the other hand, due to its rigid physical properties, such resins tend to crack easily.

[0033] On the other hand, polyoxyalkylene glycol also has a relatively linear chemical structure and has reactive groups at both ends. By using polyoxyalkylene glycol instead of 1,5-naphthalene diisocyanate, the resulting prepolymer (urethane prepolymer) also has a relatively linear structure. As a result, the polyurethane polymer chains tend to align regularly within the resulting resin 23, and the tensile strength and hardness improvement effects of 1,5-naphthalene diisocyanate are fully realized. Furthermore, the regular alignment of the polyurethane polymer chains reduces the distance between them, resulting in intermolecular interactions and improved crack resistance. Moreover, due to the ether bonds in polyoxyalkylene glycol, polyoxyalkylene glycol is relatively easy to stretch and contract. This stretching and contracting action of polyoxyalkylene glycol mitigates the rigidity of 1,5-naphthalene diisocyanate and imparts appropriate flexibility to the resin. This imparting of flexibility to the resin by polyoxyalkylene glycol also contributes to the improvement of the resin's crack resistance. In addition, polyoxyalkylene glycol functions as a soft segment within the polyurethane resin as a whole, and phase separation from the hard segment is facilitated as described above. In other words, the soft segment and the hard segment do not inhibit each other's phase separation. It is believed that the combined effects of 1,5-naphthalene diisocyanate and polyoxyalkylene glycol result in both excellent abrasion resistance and crack resistance. The following describes each component.

[0034] As described above, the isocyanate compound constituting the resin 23 contains 1,5-naphthalene diisocyanate. The content of 1,5-naphthalene diisocyanate in the isocyanate compound is not particularly limited, but is, for example, 50% by mass or more, preferably 70% by mass or more, and more preferably 90% by mass or more, relative to the isocyanate compound. The isocyanate compound is more preferably composed of essentially 1,5-naphthalene diisocyanate, and even more preferably composed of 1,5-naphthalene diisocyanate.

[0035] Furthermore, the isocyanate compound may include isocyanate compounds other than 1,5-naphthalene diisocyanate. In this case, the isocyanate compound is not particularly limited, and for example, one or more polyisocyanate compounds selected from aromatic polyisocyanates and aliphatic polyisocyanates can be used, preferably 2,4-trylene-diisocyanate (2,4-TDI), 2,6-trylene-diisocyanate (2,6-TDI), 4,4'-methylenebis(phenylisocyanate) (MDI), p-phenylene-diisocyanate (PPDI), dimethylbphenylene diisocyanate (TODI), 4,4-dibenzyle diisocyanate (DBDI), 1,6-hexamethylene diisocyanate (HDI), 1 The polyisocyanate compound may contain compounds selected from ,5-pentamethylene diisocyanate, 1-isocyanate-3-isocyanate-methyl-3,5,5-trimethylcyclohexane (IPDI), dicyclohexylmethane 4,4'-diisocyanate (H12MDI), xylylene diisocyanate (XDI), cyclohexane diisocyanate (CHDI), 1,4-bis(isocyanate-methyl)cyclohexane (H6XDI), tetramethylxylylene-diisocyanate (TMXDI), and polymethylene polyphenyl polyisocyanate (polymeric MDI), as well as mixtures thereof.

[0036] Furthermore, as mentioned above, polyol compounds include polyoxyalkylene glycol. Polyoxyalkylene glycol is a polyol that is polymerized by ether bonding between the hydroxyl groups of alkylene glycol.

[0037] The alkylene glycols that make up polyoxyalkylene glycols are 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 above-mentioned linear alkylene glycols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,5-hexanediol, 1,6-hexanediol, 2,5-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,16-hexadecanediol, 1,18-octadecanediol, and 1,20-icosanediol. 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.

[0038] Furthermore, the polyoxyalkylene glycol preferably includes a polyoxyalkylene glycol polymerized from one or more alkylene glycols having 2 to 8 carbon atoms, and more preferably a polyoxyalkylene glycol polymerized from one or more alkylene glycols having 3 to 6 carbon atoms. Such polyoxyalkylene glycols offer an excellent balance between the durability and flexibility of the resin 23.

[0039] Among those mentioned above, polyoxyalkylene glycol preferably includes linear alkylene glycol. Linear alkylene glycol contributes to improving the linearity of the prepolymer and, consequently, the backbone of the resulting polyurethane resin, and contributes to the regular arrangement of polymers in the resin 23. The polyoxyalkylene glycol, as the linear alkylene glycol mentioned above, preferably includes one or more selected from the group consisting of ethylene glycol, 1,2-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, and 1,8-octanediol; more preferably, one or more selected from the group consisting of ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol; and even more preferably, one or more selected from the group consisting of 1,3-propanediol and 1,4-butanediol. These linear alkylene glycols, due to the substitution positions of the hydroxyl groups, utilize all carbon atoms in the urethane prepolymer as a linear chain, contributing to the regular arrangement of the polymer in resin 23. Furthermore, because of the appropriate number of carbon atoms, the resin 23 using these glycols exhibits an excellent balance of durability and flexibility.

[0040] Examples of typical polyoxyalkylene glycols include polyethylene glycol, polytrimethylene ether glycol, polytetramethylene ether glycol (PTMG), polyoxypentylene glycol, and polyhexamethylene ether glycol, which are suitably used. Specifically, polyoxyalkylene glycol comprises one or more selected from the group consisting of polyethylene glycol, polytrimethylene ether glycol, polyhexamethylene ether glycol, and polytetramethylene ether glycol.

[0041] The polyol compound may contain one type of polyoxyalkylene glycol, or it may contain multiple types. Furthermore, the polyol compound may contain multiple polyoxyalkylene glycols of the same type but with different molecular weights.

[0042] The number-average molecular weight of polyoxyalkylene glycol described above is not particularly limited, but can be, for example, 250 to 5000, preferably 500 to 3000, and more preferably 600 to 2100. This allows the functions of polyoxyalkylene glycol described above to be fully exhibited. In the case of polyol compounds containing multiple types of polyoxyalkylene glycol, the number-average molecular weight measured and calculated by combining these can be used as the number-average molecular weight described above.

[0043] The number-average molecular weight of polyoxyalkylene glycol can be calculated, for example, by measuring its hydroxyl value. Specifically, first, the hydroxyl value of polyoxyalkylene glycol is measured. The hydroxyl value of polyoxyalkylene glycol can be measured in accordance with JIS K 1557-1:2007. On the other hand, the hydroxyl value (mgKOH / g) of polyoxyalkylene glycol can also be expressed as shown in the following formula I. (Hydroxyl value of polyoxyalkylene glycol (mgKOH / g)) = 56110 / (Number-average molecular weight of polyoxyalkylene glycol) × (Average number of hydroxyl groups per molecule of polyoxyalkylene glycol) (I)

[0044] Here, the average number of hydroxyl groups per molecule of polyoxyalkylene glycol is estimated to be 2.0. Therefore, the number-average molecular weight of polyoxyalkylene glycol can be expressed as shown in equation (II) below. (Number-average molecular weight of polyoxyalkylene glycol) = 112,220 / (Hydroxy value of polyoxyalkylene glycol (mgKOH / g)) (II)

[0045] In the above equation (II), the number-average molecular weight of polyoxyalkylene glycol can be determined by substituting the hydroxyl value of polyoxyalkylene glycol obtained in the measurement of hydroxyl value.

[0046] The content of polyoxyalkylene glycol in the polyol compound is not particularly limited, but is, for example, 50% by mass or more, preferably 70% by mass or more, and more preferably 90% by mass or more, relative to the polyol compound. The polyol compound is more preferably composed of polyoxyalkylene glycol in essence, and even more preferably composed of polyoxyalkylene glycol. This allows the functions of the polyoxyalkylene glycol described above to be fully exhibited. If the polyol compound contains multiple types of polyoxyalkylene glycol, the above-mentioned content may be the total content of the multiple types of polyoxyalkylene glycol.

[0047] Furthermore, the polyol compound may include polyol compounds other than polyoxyalkylene glycol. Such polyol compounds are not particularly limited and include, for example, polyester polyols such as polycaprolactone polyol and polyethylene adipate, polycarbonate diols such as polymethylene carbonate diol, polyethylene carbonate diol, polypropylene carbonate diol, polybutylene carbonate diol, polypentamethylene carbonate diol, polyhexamethylene carbonate diol, polyheptamethylene carbonate diol, and polyoctamethylene carbonate diol, polyether carbonate diol, trimethylolpropane, polybutadiene polyol, perfluoropolyether polyol, and silicon polyols such as silicon diol. One of these can be used alone or in combination of two or more.

[0048] In the polyol compound, the total content of polycarbonate polyol and polyether polycarbonate polyol is preferably 20% by mass or less, more preferably 5.0% by mass or less, and even more preferably 1.0% by mass or less. The polyol compound is even more preferably essentially free of polycarbonate polyol and polyether polycarbonate polyol, and does not contain polycarbonate polyol and polyether polycarbonate polyol. Depending on the type and content of polycarbonate polyol and polyether polycarbonate polyol, the effects of the above-mentioned combination of 1,5-naphthalene diisocyanate and polyoxyalkylene glycol may not be fully exhibited.

[0049] Furthermore, the polyurethane resin described above is obtained by reacting a urethane prepolymer X having an isocyanate group with a curing agent having an active hydrogen group. The curing agent having an active hydrogen group is not particularly limited, and a curing agent containing one or more compounds selected from the group consisting of polyol compounds and polyamines can be used.

[0050] In addition to the various polyol compounds mentioned above, the following aliphatic polyol compounds and various alicyclic or aromatic polyol compounds can be used as polyol compounds that may be included in the curing agent.

[0051] 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).

[0052] 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.

[0053] Examples of polyamines are not limited to hydrazine, but include hydrazine, ethylenediamine, 4,4'-methylene-bis-(2-chloroaniline) (MOCA), dimethylthiotoluenediamine (DMTDA), diethylthiotoluenediamine, 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 others.

[0054] Among those described above, the curing agent preferably includes one or more selected from the group consisting of aliphatic polyol compounds and aromatic polyol compounds, more preferably one or more selected from aliphatic polyol compounds, even more preferably one or more selected from 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, and 1,6-hexanediol, and particularly preferably one or more selected from 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol. These curing agents react with the prepolymer to form linear polyurethane resin polymers and contribute to the regular arrangement of the polyurethane resin polymers. As a result, the effects of the urethane prepolymer X described above are fully realized, and the resin 23 has even better abrasion resistance and crack resistance.

[0055] Furthermore, the resin 23 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 combination.

[0056] The hardness of the first resin layer 20 formed from the polyurethane resin described above, as measured using a spring-type hardness tester (Type A) in accordance with JIS K 6301:1995, is not particularly limited, but for example, at 22°C, it is 90 HS JISA or higher and 98 HS JISA or lower, preferably 91 HS JISA or higher and 97 HS JISA or lower. This allows for a sufficiently high abrasion resistance of the first resin layer 20.

[0057] The resin 33 constituting the second resin layer 30 can be one or more resin materials that can be used in the first resin layer 20 as described above. The resin 33 constituting the second resin layer 30 may be the same as or different from the resin 23 constituting the first resin layer 20 in terms of type and composition.

[0058] In particular, the resin 33 constituting the second resin layer 30 preferably contains 1,5-naphthalene diisocyanate and / or p-phenylene-diisocyanate as constituent components, and more preferably is obtained by reacting a second urethane prepolymer Y having isocyanate groups with a second curing agent having active hydrogen groups, and the second urethane prepolymer Y is obtained by reacting an isocyanate compound containing 1,5-naphthalene diisocyanate and / or p-phenylene-diisocyanate with a polyol compound containing polyoxyalkylene glycol. This further improves the crack resistance of the second resin layer 30.

[0059] In this case, the curing agent preferably includes one or more selected from the group consisting of aliphatic polyol compounds and aromatic polyol compounds, more preferably one or more selected from aliphatic polyol compounds, even more preferably one or more selected from 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, and 1,6-hexanediol, and particularly preferably one or more selected from 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol. This allows the effects of the urethane prepolymer Y described above to be fully exhibited, and the resin 33 has even better crack resistance.

[0060] Furthermore, it is preferable that the resin 33 constituting the second resin layer 30 be the same as the resin 23 of the first resin layer 20, from the viewpoint of improving the durability of the second resin layer 30 and improving the efficiency of resin production.

[0061] The resin 13 constituting the reinforcing fiber base layer 10 can be one or more resin materials that can be used in the first resin layer 20 as described above. The resin 13 constituting the reinforcing fiber base layer 10 may be the same as or different from the resin 23 constituting the first resin layer 20 in terms of type and composition. In particular, from the viewpoint of improving resin manufacturing efficiency, the resin 13 constituting the reinforcing fiber base layer 10 may be the same as the resin 23 of the first resin layer 20.

[0062] Furthermore, the resin 13 constituting the reinforcing fiber base layer 10 preferably contains 2,4-trylene-diisocyanate, 2,6-trylene-diisocyanate, and / or 1,5-naphthalene diisocyanate as constituent components. In particular, the resin 13 constituting the reinforcing fiber base layer 10 is more preferably obtained by reacting a third urethane prepolymer Z having isocyanate groups with a third curing agent having active hydrogen groups, and the third urethane prepolymer Z is obtained by reacting an isocyanate compound containing 2,4-trylene-diisocyanate, 2,6-trylene-diisocyanate, and / or 1,5-naphthalene diisocyanate with a polyol compound containing polyoxyalkylene glycol. As a result, the reinforcing fiber base layer 10 firmly supports the adjacent first resin layer 20 and second resin layer 30, further improving the durability of the shoe press belt 1, such as abrasion resistance and crack resistance.

[0063] In this case, the curing agent preferably comprises one or more selected from the group consisting of aliphatic polyol compounds and aromatic polyol compounds, more preferably one or more selected from aliphatic polyol compounds, and even more preferably one or more selected from ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,5-hexanediol, and 1,6-hexanediol, and particularly preferably one or more selected from 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol. As a result, the reinforcing fiber base layer 10 firmly supports the adjacent first resin layer 20 and second resin layer 30, further improving the durability of the shoe press belt 1, such as its abrasion resistance and crack resistance.

[0064] Here, the shoe press belt 1 described above has a total content of polycarbonate polyol and polyether polycarbonate polyol as constituent components of 5.0% by mass or less. When the inventors used 1,5-naphthalene diisocyanate as the resin component of the shoe press belt, they encountered the fact that if the shoe press belt contained a large amount of polycarbonate polyol and polyether polycarbonate polyol, the crack resistance of the shoe press belt 1 tended to decrease. They then found that in order to make the shoe press belt both crack-resistant and abrasion-resistant, the amount of polycarbonate polyol and polyether polycarbonate polyol should be kept below a certain level. The total content of polycarbonate polyol and polyether polycarbonate polyol in the shoe press belt 1 should be 5.0% by mass or less, preferably 3.0% by mass or less, and more preferably 1.0% by mass or less. The shoe press belt 1 is more preferably essentially free of polycarbonate polyols and polyether polycarbonate polyols, and particularly preferably free of polycarbonate polyols and polyether polycarbonate polyols.

[0065] In this specification, the total content of polycarbonate polyol and polyether polycarbonate polyol in the shoe press belt described above refers to the total content of polycarbonate polyol and polyether polycarbonate polyol relative to the mass of the entire shoe press belt, i.e., including not only the resins 13, 23, and 33 but also the reinforcing fiber base material 11.

[0066] The dimensions of the shoe press belt 1 described above are not particularly limited and can be set as appropriate according to its intended use. For example, the width of the shoe press belt 1 is not particularly limited, but can be 700mm to 13500mm, preferably 2500mm to 12500mm. For example, the length (circumference) of the shoe press belt 1 is not particularly limited, but can be 150cm to 1500cm, preferably 200cm to 1100cm.

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

[0068] As described above, in the shoe press belt 1 according to this embodiment, at least one of the resin 13 of the reinforcing fiber base material layer 10, the resin 23 of the first resin layer 20, and the resin 33 of the second resin layer 30 contains polyurethane resin. The polyurethane resin is obtained by reacting a urethane prepolymer X having isocyanate groups with a curing agent having active hydrogen groups. The urethane prepolymer X is obtained by reacting an isocyanate compound containing 1,5-naphthalene diisocyanate with a polyol compound containing polyoxyalkylene glycol. The shoe press belt 1 has a total content of polycarbonate polyol and polyether polycarbonate polyol as constituent components of 5.0% by mass or less. As a result, the shoe press belt 1 has excellent abrasion resistance and crack resistance simultaneously.

[0069] In particular, in the embodiment described above, the first resin layer 20 contains urethane prepolymer X as a constituent component. The first resin layer 20 is the outer circumferential resin layer of the shoe press belt 1, and its surface is constantly exposed to friction, and is a part where stress tends to concentrate and cracks are likely to occur. By including urethane prepolymer X as a constituent component in such a first resin layer 20, the wear resistance and crack resistance of the shoe press belt 1 are more reliably improved.

[0070] In the embodiments described above, the first resin layer 20 was described as containing urethane prepolymer X as a constituent component, but the present invention is not limited thereto. For example, the resin 13 of the reinforcing fiber base layer 10 or the resin 33 of the second resin layer 30 may contain urethane prepolymer X as a constituent component.

[0071] For example, the resin 33 of the second resin layer 30 may contain urethane prepolymer X as a component. The second resin layer 30 is also the inner circumferential resin layer of the shoe press belt 1, and is a part that is constantly subjected to friction with roll members and is prone to cracking. By including urethane prepolymer X as a component in the resin 33 of such a second resin layer 30, the wear resistance and crack resistance of the shoe press belt 1 are more reliably improved.

[0072] In this case, the curing agent preferably includes one or more selected from the group consisting of aliphatic polyol compounds and aromatic polyol compounds, more preferably one or more selected from aliphatic polyol compounds, even more preferably one or more selected from 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, and 1,6-hexanediol, and particularly preferably one or more selected from 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol. This allows the effects of the urethane prepolymer X described above to be fully exerted, and the wear resistance and crack resistance of the shoe press belt 1 are more reliably improved.

[0073] In this case, the resin 23 of the first resin layer 20 may include, for example, the second urethane prepolymer Y described above. Such a resin 23 also exhibits relatively good abrasion resistance and crack resistance.

[0074] In this case, the curing agent preferably includes one or more selected from the group consisting of aliphatic polyol compounds and aromatic polyol compounds, more preferably one or more selected from aliphatic polyol compounds, even more preferably one or more selected from 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, and 1,6-hexanediol, and particularly preferably one or more selected from 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol. This allows the effects of the urethane prepolymer Y described above to be fully exerted, and the wear resistance and crack resistance of the shoe press belt 1 are more reliably improved.

[0075] Next, a papermaking belt according to another embodiment of the present invention will be described. Figure 2 is a machine-cross-sectional view showing a papermaking belt according to another embodiment of the present invention. The following description will focus on the differences from the embodiments described above, and similar matters will be omitted from the description.

[0076] As shown in Figure 2, the shoe press belt 1A, used as a papermaking belt, has multiple drainage grooves 25 formed on the outer surface 21 of the first resin layer 20A. The presence of drainage grooves 25 in the shoe press belt 1A allows for more moisture to be removed from the wet paper it carries when in use.

[0077] The form of the drainage groove 25 is not particularly limited, but typically, multiple continuous grooves are formed parallel to the machine direction of the shoe press belt 1A. For example, the groove width can be set to 0.5 mm to 2.0 mm, the groove depth to 0.4 mm to 2.0 mm, and the number of grooves to 5 to 20 grooves / inch. The cross-sectional shape of the drainage groove 25 can also be set as appropriate, such as rectangular, trapezoidal, U-shaped, or with rounded edges at the land portion and the contact points between the groove bottom and the groove wall.

[0078] Furthermore, the form of these drainage channels 25 may be the same in terms of width, depth, number, and cross-sectional shape, or they may be formed by combining different shapes. Moreover, these drainage channels 25 may be formed discontinuously, or they may be formed as multiple channels parallel to the machine's transverse direction.

[0079] In the shoe press belt 1A, at least one of the resins 13 of the reinforcing fiber base layer 10, the resin 23 of the first resin layer 20A, and the resin 33 of the second resin layer 30 contains polyurethane resin. This polyurethane resin is obtained by reacting a urethane prepolymer X having isocyanate groups with a curing agent having active hydrogen groups. This urethane prepolymer X is obtained by reacting an isocyanate compound containing 1,5-naphthalene diisocyanate with a polyol compound containing polyoxyalkylene glycol. Furthermore, the shoe press belt 1A has a total content of polycarbonate polyol and polyether polycarbonate polyol as constituent components of 5.0% by mass or less. As a result, the shoe press belt 1A has excellent abrasion resistance and crack resistance simultaneously.

[0080] In the above description, the present invention was explained as an example in which the papermaking belt is a shoe press belt. However, the present invention is not limited to this, and any papermaking belt having a resin layer may be used. For example, the papermaking belt according to the present invention may be a wet paper transport belt (transfer belt) for transporting and transferring wet paper, a sleeve roll belt used in the sleeve roll of a wire section, and the like.

[0081] Here, the sleeve roll is a dewatering device positioned at the final part of the wire section. The sleeve roll includes a roll with protrusions and a flexible sleeve roll belt that surrounds the roll. As the wet paper web, held by the wire, passes through the sleeve roll, the wet paper web moves along the protrusions of the roll, removing moisture from the wet paper web as a splash. During this process, the sleeve roll belt moves together with the wet paper web and wire, reducing wear on the wire due to friction and facilitating the smooth movement of the wet paper web and wire on the sleeve roll. Preferred embodiments of the papermaking belt according to the present invention have been described above.

[0082] <2. Method for manufacturing papermaking belts> Next, preferred embodiments of the papermaking belt manufacturing method of the present invention will be described. Figures 3 to 5 are schematic diagrams illustrating preferred embodiments of the papermaking belt manufacturing method.

[0083] The present invention relates to a method for manufacturing a papermaking belt, which is a method for manufacturing a papermaking belt used in a paper machine. The process includes a step of forming a resin layer containing polyurethane resin by reacting a urethane prepolymer having isocyanate groups with a curing agent having active hydrogen groups. The urethane prepolymer is obtained by reacting an isocyanate compound containing 1,5-naphthalene diisocyanate with a polyol compound containing polyoxyalkylene glycol. The aforementioned papermaking belt has a total content of 5.0% by mass or less of polycarbonate polyol and polyether polycarbonate polyol as constituent components.

[0084] In this embodiment, a method for manufacturing a shoe press belt is described as an example of a belt for papermaking, but it goes without saying that the method for manufacturing a belt for papermaking according to the present invention is not limited to the method for manufacturing a shoe press belt. Furthermore, in this embodiment, the method for manufacturing a shoe press belt as a belt for papermaking includes a resin layer forming step of forming a first resin layer 20, a reinforcing fiber base material layer 10, and a second resin layer 30.

[0085] In the resin layer formation process, a resin layer is formed. Specifically, in this process, a laminate is formed in which a reinforcing fiber base material layer 10, in which an annular and strip-shaped reinforcing fiber base material 11 is embedded in resin 13, and a first resin layer 20 and a second resin layer 30 are laminated on both sides thereof.

[0086] Such a laminate can be formed by any method, but in this embodiment, a second resin layer 30 is formed. Next, a reinforcing fiber substrate 11 is placed on one surface of the second resin layer 30, and a resin material is applied, impregnated, and penetrated into the reinforcing fiber substrate 11 to form a laminate in which the reinforcing fiber substrate layer 10 and the second resin layer 30 are integrated. Next, a first resin layer 20 is formed on the surface of the reinforcing fiber substrate layer 10 that faces the adhesive surface between the reinforcing fiber substrate layer 10 and the second resin layer 30.

[0087] Specifically, for example, as shown in Figure 3, first, a resin material is applied to the surface of the mandrel 110, which has a release agent applied to its surface, to a thickness of 0.8 to 3.5 mm while rotating the mandrel 110 to form a resin precursor layer that will become the second resin layer 30. Next, the resin precursor layer is heated to 40 to 140°C and pre-cured for 0.5 to 1 hour to form the second resin layer 30.

[0088] Next, a reinforcing fiber substrate 11 (not shown) is placed on the pre-cured second resin layer 30, and as shown in Figure 4, a resin material to form the reinforcing fiber substrate layer 10 is applied to a thickness of 0.5 to 2.0 mm while rotating the mandrel 110, impregnating and penetrating the reinforcing fiber substrate and bonding it to the second resin layer 30, thereby forming a laminate in which the reinforcing fiber substrate layer 10 and the second resin layer 30 are integrated.

[0089] Subsequently, as shown in Figure 5, the resin material for forming the first resin layer 20 is applied and impregnated onto the surface of the reinforcing fiber base layer 10 to a thickness of 1.5 to 4 mm while rotating the mandrel 110 to form a resin precursor layer that will become the first resin layer 20. Next, the resin precursor layer is heat-cured at 70 to 140°C for 2 to 20 hours to form a laminate in which the first resin layer 20, the reinforcing fiber base layer 10, and the second resin layer 30 are stacked.

[0090] The resin material may be applied by any method, but in this embodiment, it is applied by rotating the mandrel 110 while discharging the resin material from the injection molding nozzle 130, and simultaneously applying the applied resin material uniformly using the coater bar 120.

[0091] Here, at least one of the resins 13 of the reinforcing fiber base layer 10, 23 of the first resin layer 20, and 33 of the second resin layer 30 contains a polyurethane resin. The polyurethane resin is obtained by reacting a urethane prepolymer X having isocyanate groups with a curing agent having active hydrogen groups. The urethane prepolymer X is obtained by reacting an isocyanate compound containing 1,5-naphthalene diisocyanate with a polyol compound containing polyoxyalkylene glycol. As a result, the shoe press belt 1 produced has excellent abrasion resistance and crack resistance simultaneously. The resin compositions of each resin 13, resin 23, and resin 33 can be the same as those described above. Furthermore, the components of the resin 13 of the reinforcing fiber base layer 10, the resin 23 of the first resin layer 20, and the resin 33 of the second resin layer 30 are set such that the total content of polycarbonate polyol and polyether polycarbonate polyol as constituent components in the resulting shoe press belt 1 is 5.0% by mass or less.

[0092] Furthermore, the heating method is not particularly limited, but for example, a method using a far-infrared heater can be used.

[0093] The resulting laminate is then polished or buffed on the outer surface 21 and inner surface 31 as needed, and the ends in the width direction are trimmed and trimmed as appropriate to form the shoe press belt 1. Thus, the shoe press belt 1 is manufactured.

[0094] Furthermore, when manufacturing the shoe press belt 1A, drainage grooves 25 may be formed on the outer surface 21 of the laminate formed in the resin layer formation process described above, as follows.

[0095] The drainage grooves 25 can be formed by any method, but for example, the outer surface of the laminate obtained above may be polished or buffed (not shown) to the desired thickness of the shoe press belt 1, and then, while rotating the mandrel 110, a groove processing device equipped with multiple disc-shaped rotating blades may be brought into contact with the outer surface 21 to form the drainage grooves 25.

[0096] As another embodiment of the method for manufacturing the shoe press belt in the above embodiment, for example, the following method can also be cited. First, weft threads are arranged at a fixed distance from the surface of the mandrel 110 and at regular intervals across the circumferential surface of the mandrel 110 so that their positional relationship with the mandrel 110 is fixed. Then, resin materials corresponding to the resin 33 of the second resin layer 30 and the resin 13 of the reinforcing fiber base material layer 10, and warp threads of the reinforcing fiber base material 11 are supplied to the rotating mandrel 110 to simultaneously form resin layer precursors for the second resin layer 30 and the reinforcing fiber base material layer 10. Then, while rotating the mandrel 110, the resin material for forming the first resin layer 20 is applied and impregnated onto the surface of the reinforcing fiber base material layer 10 to a thickness of 1.5 to 4 mm to form a resin precursor layer that will become the first resin layer 20. Next, the resin precursor layer is heat-cured at 70-140°C for 2-20 hours to form a laminate in which the first resin layer 20, the reinforcing fiber base layer 10, and the second resin layer 30 are laminated. The shoe press belt 1 can then be manufactured in the same manner as in the embodiment described above.

[0097] This method is efficient because it allows for the simultaneous formation of the second resin layer 30 and the reinforcing fiber base material layer 10, and eliminates the need to bond or weave the warp and weft threads of the reinforcing fiber base material.

[0098] Furthermore, the method for manufacturing the shoe press belt in the above embodiment was described as a mandrel (single roll) method. However, as another embodiment, it is also possible to employ the following two-roll method. First, an annular reinforcing fiber base material 11 is placed on two parallel rolls, and resin is applied, impregnated, and laminated onto this reinforcing fiber base material 11 to form a second resin layer 30 together with the reinforcing fiber base material layer 10. Next, this is inverted, and a first resin layer 20 is formed on the surface of the reinforcing fiber base material layer 10 after inversion. This gives rise to the shoe press belt 1. The order in which each resin layer is formed can be arbitrary.

[0099] Furthermore, although the above description described a case where the papermaking belt is a shoe press belt as an example of the present invention, the present invention is not limited to this and may also relate to a method for manufacturing any papermaking belt having a resin layer. For example, the present invention may be a method for manufacturing a papermaking belt such as a wet paper conveying belt (transfer belt), or it may be a method for manufacturing a sleeve roll belt used in the sleeve roll of a wire section.

[0100] Even in the cases described above, at least one of the resins in the resin layer contains polyurethane resin, which is obtained by reacting a urethane prepolymer X having isocyanate groups with a curing agent having active hydrogen groups. The urethane prepolymer X is obtained by reacting an isocyanate compound containing 1,5-naphthalene diisocyanate with a polyol compound containing polyoxyalkylene glycol. Furthermore, the resulting shoe press belt 1 has a total content of 5.0% by mass or less of polycarbonate polyol and polyether polycarbonate polyol as constituent components. As a result, the papermaking belt produced has excellent abrasion resistance and crack resistance simultaneously.

[0101] 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. [Examples]

[0102] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0103] 1. Manufacturing of shoe press belts and polyurethane sheet test specimens Prior to the manufacture of the shoe press belt, resin materials (urethane compositions) with the compositions of Examples 1-5 and Comparative Examples 1-6 shown in Table 1 were first prepared. For all resin materials, the urethane prepolymer and curing agent were blended so that the amount of isocyanate groups ([NCO]) of the urethane prepolymer and the amount of active hydrogen groups ([H]) of the curing agent, calculated from the NCO% (mass basis content) shown in the table, were in an equivalent ratio of [H] / [NCO] = 0.95. The amount of active hydrogen groups ([H]) was defined as the total equivalent amount of hydrogen atoms contained in the hydroxyl and amino groups of the curing agent.

[0104] In Table 1, "NDI" represents 1,5-naphthalene diisocyanate, "PPDI" represents p-phenylene diisocyanate, "MDI" represents 4,4'-methylenebis(phenylisocyanate), "TDI" represents a mixture of 2,4-trylene diisocyanate and 2,6-trylene diisocyanate, "PTMG" represents polytetramethylene glycol (number average molecular weight 997), "PCD" represents polycarbonate diol (using 1,6-hexanediol as a monomer, number average molecular weight 1993), "BD" represents 1,4-butanediol, and "HD" represents 1,6-hexanediol.

[0105] Furthermore, regarding the number-average molecular weights of polytetramethylene glycol and polyether polycarbonate diol in Table 1, their hydroxyl values ​​were measured, and the number-average molecular weights were determined from the obtained hydroxyl values ​​using formula (II) above.

[0106] Next, shoe press belts were manufactured using the resin materials of Examples 1-5 and Comparative Examples 1-6 by the following method. On the surface of a 1500 mm diameter mandrel, which can be rotated by a drive mechanism as appropriate, the resin materials of Examples 1-5 and Comparative Examples 1-6 were applied to a thickness of 1.5 mm using an injection molding nozzle that can move parallel to the rotation axis of the mandrel, while the mandrel was rotating, forming an uncured shoe-side resin layer (second resin layer). The mandrel was then left at room temperature for 10 minutes while still rotating, and then heated to 140°C using a heating device attached to the mandrel, pre-curing the shoe-side resin layer at 140°C for 1 hour.

[0107] Next, a lattice-like material, in which warp threads are sandwiched between weft threads and the intersections of the weft and warp threads are joined by urethane resin adhesive, was arranged in a single layer without gaps on the outer surface of the shoe-side resin layer, with the weft threads aligned along the axial direction of the mandrel. Here, the weft threads of the lattice-like material were twisted multifilament yarns of polyethylene terephthalate fiber with a density of 6000 dtex, and the warp threads were multifilament yarns of polyethylene terephthalate fiber with a density of 550 dtex. The warp density was 1 thread / cm and the weft density was 4 threads / cm.

[0108] Next, 30 multifilament yarns of polyethylene terephthalate fiber with a density of 6700 dtex were wound spirally around the outer circumference of the lattice-like material at a 5 cm pitch to form a yarn winding layer, and a reinforcing fiber base material was formed using this lattice-like material and yarn winding layer. Subsequently, the resin material of the reinforcing fiber base material layer (the resin material of Examples 1-5 and Comparative Examples 1-6) was applied to fill the gaps in the reinforcing fiber base material, forming a laminate in which the reinforcing fiber base material layer and the shoe-side resin layer were integrated.

[0109] Next, while rotating the mandrel, the resin material for the felt-side resin layer (resin material for Examples 1-5 and Comparative Examples 1-6) was applied to a thickness of approximately 2.9 mm using an injection molding nozzle that could move parallel to the rotation axis of the mandrel, thereby forming an uncured felt-side resin layer (first resin layer). Next, the mandrel was left at room temperature for 40 minutes while rotating, and then heated to 140°C using the heating device attached to the mandrel. Each resin layer was then heat-cured at 140°C for 4 hours. This formed a laminate in which the felt-side resin layer, the reinforcing fiber base layer, and the shoe-side resin layer were integrated. Subsequently, the felt-contact surface of the felt-side resin layer was polished to obtain a laminate with a total thickness of 5.6 mm. Drainage grooves (grooves) with a trapezoidal cross-sectional shape extending in the direction of the machine were formed in the felt-side resin layer of this laminate, with a groove depth of 1.5 mm, an upper groove width of 1.3 mm, a bottom groove width of 0.85 mm, and a groove density of 7 grooves / inch.

[0110] Through the above process, shoe press belts according to Examples 1-5 and Comparative Examples 1-6 were obtained. The hardness of the obtained shoe press belts was evaluated. The hardness of the reinforcing fiber base layer was evaluated by preparing samples of the resin constituting the reinforcing fiber base layer and evaluating the hardness of these samples.

[0111] 2. Evaluation 2.1 Crack Resistance Evaluation First, to evaluate crack resistance, test specimens S were cut from shoe press belts according to each of Examples 1-5 and Comparative Examples 1-6. The dimensions of test specimen S were 60 mm in width and 70 mm in length between grips. At this time, the longitudinal direction of test specimen S was cut so that it was perpendicular to the direction in which the grooves of the shoe press belt were formed. Therefore, the direction in which the grooves of the shoe press belt were formed was the width direction of test specimen S.

[0112] The crack resistance evaluation was performed using the bending fatigue testing apparatus shown in Figure 6, under an atmosphere of 22±3℃ and relative humidity of 50±10%. In the bending fatigue testing apparatus shown in Figure 6, 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 was 168 mm, the travel distance of the lower grip 71 was 161 mm, and the reciprocating speed of the lower grip 71 was 162 reciprocations / minute. One end of the shoe press belt test piece S in the longitudinal direction was gripped by this 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 220±5 g. Under these conditions, the bending motion was repeated, and the time until cracks occurred was observed using a video camera. Each sample was tested three times, and the average of these tests was used as the crack initiation time.

[0113] 2.2 Abrasion Resistance Evaluation The following abrasion tests were conducted to evaluate the abrasion resistance of the shoe press belts in Examples 1-5 and Comparative Examples 1-6. In the shoe press belts in Examples 1-5 and Comparative Examples 1-6, grooves are formed in the felt-side resin layer, and the belt samples after groove cutting tend to have a greater amount of abrasion than the flat sheet samples. Therefore, the test conditions were set as follows.

[0114] The abrasion test was conducted using the abrasion testing apparatus shown in Figure 7. The abrasion testing apparatus 80 shown in Figure 7 comprises a rotating roll 81 and a press board 83. The rotating roll 81 is configured to rotate, and a friction element 85 is arranged on its outer circumference. The friction element 85 is a nonwoven fabric with a surface layer made of Kevlar impregnated with epoxy resin (basis weight: 3000 ± 300 g / m²). 2The nonwoven fabric was made of Kevlar® with a thickness of 7±1mm, a fineness of 2.5dtex, and an epoxy resin of imidazole crosslinked bisphenol A. The epoxy impregnation amount was 2.5±0.5wt% of the nonwoven fabric. The press board 83 is a board positioned above the rotating roll 81 and facing the rotating roll 81, and supports the test piece S on the side facing the rotating roll 81. The press board 83 can then press the test piece S toward the rotating roll 81 with any load.

[0115] In this abrasion testing apparatus 80, first, the test piece S was attached to the lower part of the press board 83 so that the direction of groove formation was the same as the rotation direction of the rotating roll 81, that is, along the left-right direction of the paper in Figure 7. Next, the rotating roll 81 was rotated while the test piece S was pressed against the rotating roll 81 by the press board 83. At this time, the rotating roll pressed with a force of 6.6 kg per 1 cm belt width, the rotation speed of the rotating roll was set to 150 ± 3 m / min, and it was rotated for 45 seconds. Furthermore, while the rotating roll 81 was rotating, water at a water temperature of 20°C to 2°C was supplied to the test piece S by shower at a rate of 750 ± 50 cc / min. After rotation, the maximum value of the thickness reduction (amount of abrasion) of the test piece S was measured. For each of Examples 1 to 5 and Comparative Examples 1 to 6, the maximum value of the thickness reduction of the test piece S was measured twice, and the average value was taken as the amount of abrasion. The obtained results are shown in Table 1.

[0116] [Table 1]

[0117] As shown in Table 1, the shoe press belts according to Examples 1 to 5 exhibited excellent abrasion resistance and crack resistance simultaneously. In contrast, the shoe press belts according to Comparative Examples 1 to 6 had excellent abrasion resistance, but poor crack resistance, particularly in the felt-side resin layer. Cracks typically tend to occur in the felt-side resin layer, and from this, it can be understood that the shoe press belts according to Examples 1 to 5 have a significantly longer product life compared to the shoe press belts according to Comparative Examples 1 to 6. [Explanation of Symbols]

[0118] 1. 1A Papermaking belt (shoe press belt) 10 Reinforcement fiber base layer 11 Reinforcement fiber base material 13 Resin 20, 20A First resin layer 21 Outer surface 23 Resin 25 Drainage 30 Second resin layer 31 Inner surface 33 Resin

Claims

1. A papermaking belt used in a paper machine, Having a resin layer containing polyurethane resin, The polyurethane resin is obtained by reacting a urethane prepolymer having isocyanate groups with a curing agent having active hydrogen groups. The urethane prepolymer is obtained by reacting an isocyanate compound containing 1,5-naphthalene diisocyanate with a polyol compound containing polyoxyalkylene glycol. A papermaking belt in which the total content of polycarbonate polyol and polyether polycarbonate polyol as constituent components is 5.0% by mass or less.

2. The papermaking belt according to claim 1, wherein the polyoxyalkylene glycol comprises a polyoxyalkylene glycol obtained by polymerizing one or more alkylene glycols having 2 to 8 carbon atoms.

3. The papermaking belt according to claim 1, wherein the polyoxyalkylene glycol comprises one or more selected from the group consisting of polyethylene glycol, polytrimethylene ether glycol, polyhexamethylene ether glycol, and polytetramethylene ether glycol.

4. The papermaking belt according to claim 1, wherein the number average molecular weight of the polyoxyalkylene glycol is 500 or more and 3000 or less.

5. Forming a ring, The papermaking belt according to claim 1, wherein the resin layer is an outer peripheral resin layer located on the outer peripheral side.

6. Furthermore, it has an inner circumferential resin layer located on the inner circumferential side and containing a second polyurethane resin, The papermaking belt according to claim 5, wherein the second polyurethane resin comprises 1,5-naphthalene diisocyanate and / or p-phenylene diisocyanate as constituent components.

7. The second polyurethane resin is obtained by reacting a second urethane prepolymer having isocyanate groups with a second curing agent having active hydrogen groups. The papermaking belt according to claim 6, wherein the second urethane prepolymer is obtained by reacting an isocyanate compound containing 1,5-naphthalene diisocyanate and / or p-phenylene-diisocyanate with a polyol compound containing polyoxyalkylene glycol.

8. Furthermore, the material is disposed between the resin layer and the inner circumferential resin layer and comprises a reinforcing fiber base material and a reinforcing fiber base material layer containing a third polyurethane resin impregnated into the reinforcing fiber base material. The papermaking belt according to claim 6, wherein the third polyurethane resin comprises 2,4-trylene-diisocyanate, 2,6-trylene-diisocyanate and / or 1,5-naphthalene diisocyanate as constituent components.

9. Forming a ring, The papermaking belt according to any one of claims 1 to 4, wherein the resin layer is an inner circumferential resin layer located on the inner circumferential side.

10. The papermaking belt according to claim 1, wherein the polycarbonate polyol and the polyether polycarbonate polyol are not included as constituent components.

11. A papermaking belt according to claim 1, which is a shoe press belt.

12. A papermaking belt according to claim 1, which is a sleeve roll belt.

13. A method for manufacturing papermaking belts used in papermaking machines, The process includes a step of forming a resin layer containing polyurethane resin by reacting a urethane prepolymer having isocyanate groups with a curing agent having active hydrogen groups. The urethane prepolymer is obtained by reacting an isocyanate compound containing 1,5-naphthalene diisocyanate with a polyol compound containing polyoxyalkylene glycol. The method for manufacturing a papermaking belt, wherein the papermaking belt has a total content of polycarbonate polyol and polyether polycarbonate polyol as constituent components of 5.0% by mass or less.

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