Boot-shaped press belt and method for producing a boot-shaped press belt

Abstract

This invention provides a boot-shaped press belt with suppressed strength imbalances between components and excellent strength, as well as a method for preparing the boot-shaped press belt. A boot-shaped press belt for a paper machine has at least one resin layer comprising a polyurethane resin containing an isocyanate prepolymer cured by a curing agent having active hydrogen groups. The urethane prepolymer is obtained by reacting a polyisocyanate compound containing 4,4'-methylenebis(phenyl isocyanate) with a polyol compound containing polytetramethylene ether diol. The curing agent comprises polycarbonate diol.

Description

Technical Field

[0001] This invention relates to a boot-shaped press belt and a method for preparing the boot-shaped press belt. Background Technology

[0002] Paper machines that remove moisture from paper raw materials typically include a wire section, a press section, and a drying section. These sections are arranged sequentially along the direction of the wet paper's transport.

[0003] The wet paper is sequentially transferred to each papermaking tool in the wire section, press section, and drying section, and moisture is removed during the conveying process, with final drying taking place in the drying section. In each of these sections, papermaking tools are used that correspond to each function, such as wet paper dewatering (wire section), press water removal (press section), and drying (drying section).

[0004] The press section typically includes one or more press units arranged in series along the feed direction of the wet paper. Each press unit is equipped with an annular felt, or an annular felt formed by connecting felt to the ends of the paper machine. Furthermore, each press unit has a roll pressing mechanism consisting of a pair of opposing rolls, or a boot-shaped press mechanism with an annular press belt sandwiched between concave boots facing the rolls. The felt, on which the wet paper is placed, is pressed by moving along the feed direction of the wet paper and passing through the roll pressing mechanism or the boot-shaped press mechanism, causing the felt to continuously absorb moisture or to discharge moisture through the interior of the felt to the exterior, thereby squeezing moisture from the wet paper.

[0005] In boot-shaped press belts, a reinforcing substrate is typically embedded in the resin, which forms an outer peripheral layer that contacts the felt and an inner peripheral layer that contacts the boot. Furthermore, because the boot-shaped press belt reciprocates between the pressurized roller and the boot, the resin used in the boot-shaped press belt is required to have excellent durability.

[0006] Patent Document 1 provides a boot-shaped press belt. In the boot-shaped press belt with drainage grooves, a reinforcing substrate is embedded in polyurethane for the purpose of preventing breakage or damage to the welded area constituting the drainage grooves and suppressing the generation of cracks. The boot-shaped press belt is integrally formed by the polyurethane and the reinforcing substrate. At least the polyurethane constituting the outer peripheral surface of the boot-shaped press belt is a thermosetting polyurethane obtained by curing a urethane prepolymer using a curing agent. The urethane prepolymer includes a first urethane prepolymer, which is obtained by reacting a polyol component containing a specified linear aliphatic polycarbonate diol with an aromatic diisocyanate.

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: Japanese Patent Application Publication No. 2016-199813 Summary of the Invention

[0010] Technical issues

[0011] The boot-shaped press belt with a polyurethane layer containing a component of linear aliphatic polycarbonate diol as a urethane prepolymer exhibits excellent strength. However, the inventors have discovered that when using linear aliphatic polycarbonate diol as a component of the urethane prepolymer, an uneven strength occurs between the components of the resulting boot-shaped press belt. If this uneven strength exists between the components of the boot-shaped press belt, damage and deterioration begin in the weaker sections, making it difficult to improve the durability of the boot-shaped press belt.

[0012] Therefore, the object of the present invention is to provide a boot-shaped press belt with excellent strength and suppressed strength imbalance between components, and a method for preparing the boot-shaped press belt.

[0013] Solution to the problem

[0014] As a result of intensive research to achieve the above objectives, the inventors discovered that the strength of the polyurethane layer constituting the boot-shaped press belt can be improved and the uneven strength can be suppressed by using a curing agent containing polycarbonate diol to cure a polyurethane prepolymer obtained by reacting a polyisocyanate compound containing 4,4'-methylene bis(phenyl isocyanate) with a polyol compound containing polytetramethylene ether diol. This led to the completion of the present invention.

[0015] The gist of this invention is as follows.

[0016] [1] A boot-shaped press belt for a paper machine,

[0017] Having at least one resin layer,

[0018] The aforementioned resin layer comprises a polyurethane resin containing isocyanate groups cured by a curing agent with active hydrogen groups onto a urethane prepolymer.

[0019] The above-mentioned urethane prepolymer is obtained by reacting a polyisocyanate compound containing 4,4'-methylene bis(phenyl isocyanate) with a polyol compound containing polytetramethylene ether diol.

[0020] The curing agent mentioned above contains polycarbonate diol.

[0021] [2] According to the boot-shaped press belt described in [1],

[0022] The curing agent described above contains polycarbonate diol X containing one or more units A represented by the following formula (1).

[0023] Chemical Formula 1:

[0024] In equation (1),

[0025] R 1 It is a branched alkylene group having 3 or more but less than 20 carbon atoms.

[0026] [3] According to the boot-shaped press belt described in [2], R 1 The group consisting of 3-methylpentenyl, 2,2-dimethylpropenyl, 2-methyloctenyl, 2-butyl-2-ethylpropenyl and 2,2,4-trimethyl-1,6-hexenyl is selected.

[0027] [4] According to the boot-shaped press belt described in [2] or [3],

[0028] The aforementioned polycarbonate diol X further comprises one or more units B represented by the following formula (2),

[0029] Chemical formula 2:

[0030] In equation (2),

[0031] R 2 It is a straight-chain alkylene group having 1 or more but less than 20 carbon atoms.

[0032] [5] The boot-shaped press belt according to any one of [1] to [4],

[0033] The curing agent described above contains one or more polycarbonate diols Y represented by the following formula (3),

[0034] Chemical formula 3: HO-Cm-Dn-R 3 OH (3),

[0035] In equation (3),

[0036] C and D are distinct units represented by the following equation (4).

[0037] Chemical formula 4:

[0038] R 3 It is a straight-chain, branched, or cyclic alkylene group having 1 or more but less than 20 carbon atoms.

[0039] m and n are independent integers greater than 1 and less than 46.

[0040] In equation (4), R 4 It is a straight-chain alkylene group having 1 or more but less than 20 carbon atoms.

[0041] [6] According to the boot-shaped press belt described in [5],

[0042] In the above formula (3),

[0043] In C, R 4 It is n-propenyl, and in D, R 4 It is n-butenyl, or

[0044] In C, R 4 It is n-butenyl, and in D, R 4 It is n-hexenyl or n-decenyl, or

[0045] In C, R 4 It is n-pentenyl, and in D, R 4 It is n-hexenyl, or

[0046] In C, R 4 It is n-hexenyl, and in D, R 4 It is n-undecenyl or n-dodecenyl, or

[0047] In C, R 4 It is an undecenyl group, and in D, R 4 It is n-dodecenyl.

[0048] [7] According to any one of [1] to [6], the resin layer constitutes the outer peripheral surface of the boot-shaped press belt and has a layer containing the polyurethane resin.

[0049] [8] According to any one of [1] to [7], the resin layer constitutes the inner circumferential surface of the boot-shaped press belt and has a layer containing the polyurethane resin.

[0050] [9] A method for preparing a boot-shaped press belt for a paper machine.

[0051] The process includes the step of curing an isocyanate prepolymer with a curing agent having active hydrogen groups to form a resin layer.

[0052] The above-mentioned urethane prepolymer is obtained by reacting a polyisocyanate compound containing 4,4'-methylene bis(phenyl isocyanate) (MDI) with a polyol compound containing polytetramethylene ether diol.

[0053] The curing agent mentioned above contains polycarbonate diol.

[0054] The effects of the invention

[0055] The above structure provides a boot-shaped press belt with suppressed strength imbalance between components and excellent strength, as well as a method for preparing the boot-shaped press belt. Attached Figure Description

[0056] Figure 1 A cross-sectional view of a machine for illustrating a boot-shaped press belt according to an embodiment of the present invention.

[0057] Figure 2 A cross-sectional view of a machine for illustrating a boot-shaped press belt according to another embodiment of the present invention.

[0058] Figure 3 This is a simplified diagram illustrating a preferred embodiment of the method for preparing the boot-shaped press belt according to the present invention.

[0059] Figure 4 This is a simplified diagram illustrating a preferred embodiment of the method for preparing the boot-shaped press belt according to the present invention.

[0060] Figure 5 This is a simplified diagram illustrating a preferred embodiment of the method for preparing the boot-shaped press belt according to the present invention.

[0061] Explanation of reference numerals in the attached figures

[0062] 1.1A: Boot-shaped press belt

[0063] 10: Reinforcing fiber substrate layer

[0064] 11: Reinforced fiber substrate

[0065] 13: Resin

[0066] 20, 20A: First resin layer

[0067] 21: Peripheral surface

[0068] 23: Resin

[0069] 25: Drainage ditch

[0070] 30: Second resin layer

[0071] 31: Inner peripheral surface

[0072] 33: Resin Detailed Implementation

[0073] Hereinafter, preferred embodiments of the boot-shaped press belt and the method for preparing the boot-shaped press belt according to the present invention will be described in detail with reference to the accompanying drawings.

[0074] 1. Boot-shaped press belt

[0075] First, the boot-shaped press belt according to a preferred embodiment of the present invention will be described.

[0076] Figure 1This is a cross-sectional view of a machine illustrating an example of a boot-shaped press belt according to a preferred embodiment of the present invention. In the figure, the size of each component is appropriately emphasized for ease of explanation, but the actual proportions and sizes of each component are not shown. The cross-machine direction is also referred to as "CMD," and the machine direction is also referred to as "MD."

[0077] Figure 1 The boot-shaped press belt 1 shown is used in the press section of a paper machine, more specifically in the boot-shaped press mechanism, to transport wet paper and squeeze moisture from the wet paper in cooperation with the felt. The boot-shaped press belt 1 forms an annular belt. That is, the boot-shaped press belt 1 is an annular belt. Moreover, the boot-shaped press belt 1 is generally configured such that its circumferential direction is along the machine longitudinal direction (MD) of the paper machine.

[0078] Figure 1 The boot-shaped press belt 1 shown includes a reinforcing fiber substrate layer 10, a first resin layer 20 disposed on one main surface of the reinforcing fiber substrate layer 10, and a second resin layer 30 disposed on another main surface of the reinforcing fiber substrate layer 10, and is formed by stacking these layers.

[0079] 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 to fill the gaps between the fibers in the reinforcing fiber substrate 11. That is, a portion of the resin 13 is impregnated in the reinforcing fiber substrate 11, while the reinforcing fiber substrate 11 is embedded in the resin 13.

[0080] The reinforcing fiber substrate 11 is not particularly limited; for example, a fabric in which warp and weft yarns are woven on a loom or similar means is commonly used. Furthermore, a lattice-like material obtained by overlapping warp and weft rows without weaving can also be used. Alternatively, two or more fabrics and lattice-like materials can be used in combination.

[0081] The fineness of the fibers constituting the reinforcing fiber substrate 11 is not particularly limited. For example, it can be 300 to 10,000 dtex, and preferably 500 to 6,000 dtex.

[0082] Furthermore, the fineness of the fibers constituting the reinforcing fiber substrate 11 can vary depending on the part where the fibers are used. For example, the warp and weft yarns of the reinforcing fiber substrate 11 can also have different finenesses.

[0083] As the reinforcing fiber substrate 11, two or more types of materials can be used alone or in combination, such as polyester (polyethylene terephthalate and polybutylene terephthalate, etc.), aliphatic polyamide (polyamide 6, polyamide 11, polyamide 12 and polyamide 612, etc.), aromatic polyamide (aromatic polyamide), polyvinylidene fluoride, polypropylene, polyether ether ketone, polytetrafluoroethylene, polyethylene, wool and cotton, and metals, etc.

[0084] Furthermore, resin 13 will be described below.

[0085] The first resin layer 20 is a resin layer disposed on a main surface located on the outer surface side of the reinforcing fiber substrate layer 10, and is composed of resin 23. The first resin layer 20 forms the outer peripheral surface 21, on which wet paper is carried and conveyed by a felt blanket when the boot-shaped press belt 1 is used.

[0086] The second resin layer 30 is a resin layer disposed on another main surface located on the inner surface side of the reinforcing fiber substrate layer 10, and is composed of resin 33. The second resin layer 30 forms an inner peripheral surface 31, which is configured to contact the boot of the boot-shaped pressing mechanism (not shown) when the boot-shaped pressing belt 1 is used.

[0087] The resin 13 in the reinforcing fiber substrate layer 10 of the boot-shaped press belt 1, the resin 23 constituting the first resin layer 20, and the resin 33 constituting the second resin layer 30 will be explained.

[0088] Furthermore, in this embodiment, at least one of the reinforcing fiber substrate layer 10, the first resin layer 20, and the second resin layer 30 of the boot-shaped press belt 1 comprises a polyurethane resin P containing an isocyanate prepolymer cured by a curing agent having active hydrogen groups. Moreover, the urethane prepolymer used to prepare the polyurethane resin P is obtained by reacting a polyisocyanate compound containing 4,4'-methylenebis(phenyl isocyanate) with a polyol compound containing polytetramethylene ether diol, and the curing agent comprises polycarbonate diol.

[0089] Furthermore, since resins 13, 23, and 33 can have the same composition, resin 23 of the first resin layer 20 will be described in detail below as representative. In the following description, the case where resin 23 includes the aforementioned polyurethane resin P will be emphasized.

[0090] As described above, the polyurethane resin P constituting resin 23 comprises a polyurethane resin P containing an isocyanate prepolymer cured by a curing agent having active hydrogen groups. Furthermore, the urethane prepolymer used to prepare the polyurethane resin P is obtained by reacting a polyisocyanate compound containing 4,4'-methylenebis(phenyl isocyanate) with a polyol compound containing polytetramethylene ether diol, and the curing agent comprises polycarbonate diol. Thus, in the first resin layer 20 composed of resin 23, the strength of the first resin layer 20 is increased while suppressing strength imbalance; as a result, the strength of the boot-shaped press belt 1 is increased while suppressing strength imbalance between its components.

[0091] The polyurethane layer containing linear aliphatic polycarbonate diol as a component of urethane prepolymer exhibits excellent strength. However, the inventors have discovered that when using linear aliphatic polycarbonate diol as a component of urethane prepolymer, strength imbalance occurs between the components of the resulting boot-shaped press belt. If strength imbalance exists between the components of the boot-shaped press belt, damage and deterioration begin at the weakest points, making it difficult to improve the durability of the boot-shaped press belt.

[0092] Furthermore, through dedicated research to explain the cause, the inventors discovered that if a linear aliphatic polycarbonate diol is used alone to prepare the urethane prepolymer, the viscosity of the polyurethane composition containing the urethane prepolymer, curing agent, and the urethane prepolymer increases significantly, making it difficult to uniformly distribute the polyurethane composition when preparing the boot-shaped press belt. In this case, it is difficult to form a uniform polyurethane layer.

[0093] On the other hand, the inventors have discovered that when using a urethane prepolymer obtained by reacting a polyisocyanate compound containing 4,4'-methylene bis(phenyl isocyanate) with a polyol compound containing polytetramethylene ether diol, even when a curing agent containing polycarbonate diol is mixed in, the viscosity increase of the resulting polyurethane composition can be suppressed, forming a uniform resin layer of polyurethane resin P. Furthermore, it has been found that when a resin layer is formed using polyurethane resin P obtained in this manner, not only is the strength imbalance between components of the boot-shaped press belt suppressed, but the overall strength of the boot-shaped press belt is also improved.

[0094] Furthermore, in this specification, unless otherwise stated, "between components" refers to any component in the planar direction of the resin layers constituting the boot-shaped press belt, that is, any component in the resin layers formed of the same material. For example, in the boot-shaped press belt 1 according to this embodiment, any component in the planar direction of each resin layer can be compared in each reinforcing fiber substrate layer 10, the first resin layer 20, and the second resin layer 30. Moreover, the strength imbalance between components in each resin layer has a complex effect on the boot-shaped press belt, resulting in a strength imbalance between the components constituting the boot-shaped press belt itself.

[0095] Specifically, in this invention, the curing agent contains polycarbonate diol. When polycarbonate diol is used as a component of the urethane prepolymer, the viscosity of the reaction solution increases during the synthesis of the urethane prepolymer. In this case, the urethane prepolymer itself becomes non-uniform, and the viscosity of the urethane prepolymer increases. As a result, even when mixing the urethane prepolymer, it cannot be uniformly mixed, and the non-uniformity of the obtained polyurethane composition increases. On the other hand, in this invention, by including the aforementioned polycarbonate diol in the curing agent, the viscosity increase of the urethane prepolymer is suppressed while making the composition of the urethane prepolymer uniform, and it is not necessary to include polycarbonate diol in the urethane prepolymer. Furthermore, by mixing the urethane prepolymer and the curing agent, which suppress the viscosity increase, the urethane prepolymer and the curing agent are mixed more uniformly, and a more uniform polyurethane composition with suppressed viscosity increase is obtained.

[0096] In particular, the inventors have discovered that urethane prepolymers obtained by reacting an isocyanate compound containing 4,4'-methylene bis(phenyl isocyanate) with a polyol containing polytetramethylene ether glycol are difficult to increase the viscosity of the polyurethane composition even when mixed with polycarbonate diol. Therefore, in this embodiment, the uneven strength between the components of the first resin layer 20, which is a polyurethane resin layer formed using the polyurethane composition, is suppressed.

[0097] Furthermore, by including polycarbonate diol in the curing agent, the strength of the first resin layer 20, which forms the polyurethane resin layer, is improved.

[0098] Furthermore, the first resin layer 20 forms the outer peripheral surface 21 of the boot-shaped press belt 1. In the boot-shaped press belt 1, the outer peripheral surface 21 is a region prone to wear and tear due to contact friction with felt or the like during use, and to cracking or other damage due to bending fatigue. Therefore, the first resin layer 20 forming the outer peripheral surface 21 of the boot-shaped press belt 1 improves the durability of the boot-shaped press belt 1 by including a polyurethane resin P formed using a curing agent containing polycarbonate diol.

[0099] The components of resin 23 will be described below. As described above, resin 23 comprises a polyurethane resin P, which is a urethane prepolymer having isocyanate groups, cured by a curing agent having active hydrogen groups.

[0100] A urethane prepolymer with isocyanate groups can be obtained by reacting a polyisocyanate compound with a polyol compound. The polyisocyanate compound contains 4,4'-methylenebis(phenylisocyanate), and the polyol compound contains polytetramethylene ether glycol. This process suppresses the viscosity increase of the urethane prepolymer and even the polyurethane composition, and helps to prevent strength imbalances between the components of the resulting boot-shaped press belt 1.

[0101] Furthermore, the polyisocyanate compound may also include polyisocyanate compounds other than 4,4'-methylenebis(phenylisocyanate). In this case, there is no particular limitation on the polyisocyanate compound; for example, one or more polyisocyanate compounds selected from aromatic and aliphatic polyisocyanates may be used. Preferably, it may include 2,4-toluene diisocyanate (2,4-TDI), 2,6-toluene diisocyanate (2,6-TDI), p-phenylene diisocyanate (PPDI), dimethyl biphenyl diisocyanate (TODI), naphthalene-1,5-diisocyanate (NDI), 4,4-dibenzyl diisocyanate (DBDI), and 1,6-hexamethylene diisocyanate. Methyl diisocyanate (HDI), 1,5-pentamethylene diisocyanate, 1-isocyanate-3-isocyanate methyl-3,5,5-trimethylcyclohexane (IPDI), dicyclohexylmethane-4,4'-diisocyanate (H12MDI), xylene diisocyanate (XDI), cyclohexane diisocyanate (CHDI), 1,4-bis-(isocyanate methyl)cyclohexane (H6XDI), tetramethylxylene diisocyanate (TMXDI), polymethylene polyphenyl polyisocyanate (Polymeric MDI), and polyisocyanate compounds having compounds selected from these mixtures.

[0102] Furthermore, the polyol compound may also include polyol compounds other than polytetramethylene ether glycol. There are no particular limitations on the polyol compound; for example, examples include polyester polyols such as polycaprolactone polyol and polyvinyl adipate, polyether polyols such as polyethylene glycol, polyoxypropylene glycol, and polyhexamethylene ether glycol, and long-chain polyols such as linear aliphatic polycarbonate glycol, polyether carbonate glycol, trimethylolpropane, polybutadiene polyol, perfluoropolyether polyol, and silicone glycol. One of these compounds may be used alone or in combination of two or more.

[0103] Examples of linear aliphatic polycarbonate diols include 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.

[0104] As described above, the curing agent contains polycarbonate diol. There is no particular limitation on the polycarbonate diol, but the curing agent preferably contains, for example, a polycarbonate diol X containing unit A represented by the following formula (1) as the polycarbonate diol.

[0105] Chemical formula 5:

[0106] In equation (1),

[0107] R 1 It is a branched alkylene group having 3 or more but less than 20 carbon atoms.

[0108] Because this polycarbonate diol X contains branched alkylene groups, it has low crystallinity. This further suppresses the viscosity increase of the polyurethane composition and further suppresses the strength imbalance between the components of the boot-shaped press belt 1.

[0109] In the above equation (1), R 1 It is a branched alkylene group having 3 or more but less than 20 carbon atoms, and the same or different each time it appears. Specifically, R 1 It can be an alkylene group having 3 or more and 20 or less carbon atoms, as represented by the following formula (5).

[0110] Chemical Formula 6:

[0111] In equation (5), R 5 It is a straight-chain or branched alkyl group.

[0112] R 6 It is H or a straight-chain or branched alkyl group.

[0113] R 7 It is a straight-chain or branched alkylene group.

[0114] A is an integer greater than or equal to 0.

[0115] In R 5 and R 6 Examples of straight-chain alkyl groups include methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, and n-dodecyl. Furthermore, in R... 5 and R 6 Examples of branched alkyl groups include isopropyl, tert-butyl, and isobutyl.

[0116] R 5 Preferably, it is a straight-chain or branched alkyl group having 1 or more and 4 or less carbon atoms, more preferably it is selected from the group consisting of methyl, ethyl, n-propyl, n-butyl and isopropyl, and even more preferably it is methyl, ethyl or n-butyl.

[0117] R 6 Preferably, it is H or a straight-chain or branched alkyl group having 1 or more and 4 or less carbon atoms, more preferably one selected from the group consisting of H, methyl, ethyl, n-propyl and isopropyl, and even more preferably H, methyl or ethyl.

[0118] R 7 Examples of straight-chain alkylene groups include methylene, vinyl, n-propenyl, n-butenyl, n-pentenyl, n-hexenyl, n-heptenyl, and n-octenyl, which are straight-chain alkylene groups having 1 or more but less than 10 carbon atoms. 7 Branched alkylene groups can be exemplified by 1-methylpropenyl, 2-methylpropenyl, 1,1-dimethylpropenyl, 1,2-dimethylpropenyl, 1,3-dimethylpropenyl, 2,2-dimethylpropenyl, 1,2,3-trimethylpropenyl, 1,1,2-trimethylpropenyl, 1,2,2-trimethylpropenyl, 1,1,3-trimethylpropenyl, 1-methylbutenyl, 2-methylbutenyl, 1,1-dimethylbutenyl, 1,2-dimethylbutenyl It includes 1,3-dimethylbutenyl, 1,4-dimethylbutenyl, 2,2-dimethylbutenyl, 2,3-dimethylbutenyl, 1,2,3-trimethylbutenyl, 1,2,4-trimethylbutenyl, 1,1,2-trimethylbutenyl, 1,2,2-trimethylbutenyl, 1,3,3-trimethylbutenyl, 1-methylpentenyl, 2-methylpentenyl, 3-methylpentenyl, 1-methylhexenyl, 2-methylhexenyl, and 3-methylhexenyl, etc.

[0119] R 7 Preferably, it is a straight-chain alkylene group having 1 or more and 10 or less carbon atoms, more preferably a straight-chain alkylene group having 1 or more and 8 or less carbon atoms, and even more preferably a group selected from the group consisting of methylene, vinyl and n-hexenyl.

[0120] In the above formula (5), a is an integer greater than or equal to 0. a is preferably greater than or equal to 1. The upper limit of A is a number that makes the number of carbon atoms in formula (5) 20, and is less than or equal to 17. a is preferably less than or equal to 6, and more preferably less than or equal to 3.

[0121] Particularly preferred, R 1The components are selected from 3-methylpentenyl, 2,2-dimethylpropenyl, 2-methyloctenyl, 2-butyl-2-ethylpropenyl, and 2,2,4-trimethyl-1,6-hexenyl. This further reduces the viscosity of the obtained polyurethane composition and further reduces imbalances between components of the boot-shaped press belt 1, while also further improving the strength of the boot-shaped press belt 1.

[0122] Furthermore, polycarbonate diol X may further comprise one or more units B represented by the following formula (2),

[0123] Chemical Formula 7:

[0124] In equation (2),

[0125] R 2 It is a straight-chain alkylene group having 1 or more but less than 20 carbon atoms.

[0126] Therefore, the viscosity increase of the obtained polyurethane composition can be suppressed, the strength imbalance between the components of the boot-shaped press belt 1 can be suppressed, and the strength of the boot-shaped press belt 1 can be further improved.

[0127] As mentioned above, R 2 It is a straight-chain alkylene group having 1 or more but less than 20 carbon atoms. R 2 Examples include methylene, vinyl, propenyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, dodecenyl, tridecenyl, tetradecenyl, pentadecenyl, hexadecenyl, heptadecenyl, octadecenyl, nonadecenyl, and icosenoyl.

[0128] As mentioned above, R 2 The carbon number is 1 or more and 20 or less, but to suppress excessive viscosity increase in the obtained polyurethane composition, it is preferably 2 or more, more preferably 3 or more. Furthermore, to improve the strength of the obtained polyurethane resin, R... 2 The number of carbon atoms is preferably 15 or less, more preferably 12 or less.

[0129] Particularly preferred, R 2 The group consisting of n-butenyl, n-hexenyl, n-nonenyl, n-decenyl, n-undecenyl, and n-dodecenyl is selected. This allows for the suppression of excessive viscosity in the obtained polyurethane composition while further improving the strength of the obtained polyurethane resin.

[0130] Furthermore, the ratio of unit B to unit A is, for example, a copolymerization ratio of 5% or more and 95% or less (unit B / unit A (Mol / Mol)), preferably 10% or more and 90% or less.

[0131] Polycarbonate diol X having the above-mentioned unit A and unit B is represented, for example, by the following formula (6).

[0132] Chemical formula 8: HO-A k -B / -R 8 OH (6),

[0133] In equation (6), A independently represents unit A in each occurrence, B independently represents unit B in each occurrence, K and l are mutually independent integers greater than 1 and less than 40, and R 8 For R 1 Or R 2 .

[0134] K and l are preferably integers of 1 or more and 34 or less, and more preferably integers of 1 or more and 29 or less.

[0135] Furthermore, the ratio of K to l represents the ratio (number ratio) of groups A and B. There is no particular limitation on k / l, for example, it is 0.01 or more and 30 or less, preferably 0.02 or more and 19 or less, and more preferably 0.1 or more and 10 or less.

[0136] Furthermore, in the polycarbonate diol X represented by formula (6), there are no particular limitations on the arrangement of unit A and unit B. That is, the polycarbonate diol X represented by formula (6) can be a random copolymer, an alternating copolymer, or a block copolymer. Moreover, the polycarbonate diol X represented by formula (6) may also contain multiple types of unit A and / or multiple types of unit B.

[0137] Furthermore, in addition to units A and B mentioned above, polycarbonate diol X may also contain units with cyclic alkylene groups. Such cyclic alkylene groups may be a group having an alicyclic group such as a cyclopentane ring, cyclohexane ring, cycloheptane ring, or cyclooctane ring. In this case, the cyclic alkylene group is bonded directly from the alicyclic group or through an alkylene group having 1 to 3 carbon atoms substituted by an alicyclic group to an adjacent oxygen atom. Examples of such cyclic alkylene groups include 1,4-cyclohexanedimethylbis(methylene).

[0138] The number-average molecular weight of the polycarbonate diol X is not particularly limited; for example, it can be 250 or more and 4000 or less, preferably 500 or more and 3000 or less. Furthermore, the number-average molecular weight of the polycarbonate diol can be calculated, for example, by measuring the hydroxyl value.

[0139] Specifically, firstly, the hydroxyl value of polycarbonate diol X is measured. The hydroxyl value of polycarbonate diol X can be measured according to JIS K1557-1:2007. Alternatively, the hydroxyl value (MgKOH / g) of polycarbonate diol X can also be expressed as Formula I below.

[0140] (Hydroxyl value of polycarbonate diol X (MgKOH / g)) = 56110 / (Number average molecular weight of polycarbonate diol X) × (Average number of hydroxyl groups per molecule of polycarbonate diol X) (I)

[0141] The average number of hydroxyl groups per molecule of polycarbonate diol X is estimated to be 2.0. Therefore, the number-average molecular weight of polycarbonate diol X can be expressed as follows (II).

[0142] (Number-average molecular weight of polycarbonate diol X) = 112220 / (Hydroxy value of polycarbonate diol X (MgKOH / g)) (II)

[0143] In formula (II) above, the number-average molecular weight of polycarbonate diol X can be calculated by substituting the hydroxyl value of polycarbonate diol X obtained in the hydroxyl value measurement. Furthermore, polycarbonate diols other than polycarbonate diol X can be calculated in the same manner.

[0144] Furthermore, the curing agent may also contain polycarbonate diol Y represented by the following formula (3). The polycarbonate diol Y described below can suppress the viscosity increase of the polyurethane composition and further suppress the strength imbalance between the components of the obtained boot-shaped press belt 1.

[0145] Chemical formula 9: HO-Cm-Dn-R 3 OH (3),

[0146] In equation (3),

[0147] C and D are distinct units represented by the following equation (4).

[0148] Chemical Formula 10:

[0149] R 3 It is a straight-chain, branched, or cyclic alkylene group having 1 or more but less than 20 carbon atoms.

[0150] m and n are independent integers greater than 1 and less than 46.

[0151] In equation (4), R 4 It is a straight-chain alkylene group having 1 or more but less than 20 carbon atoms.

[0152] In equation (3) above, C and D are distinct groups represented by equation (4). In equation (4), R 4Examples include methylene, vinyl, propenyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, dodecenyl, tridecenyl, tetradecenyl, pentadecenyl, hexadecenyl, heptadecenyl, octadecenyl, nonadecenyl, and icosyl.

[0153] In C, R 4 Preferably, it is a straight-chain alkylene group having 2 or more and 18 or less carbon atoms, more preferably a straight-chain alkylene group having 3 or more and 11 or less carbon atoms. Similarly, in D, R 4 Preferably, it is a straight-chain alkylene group having 3 or more and 19 or less carbon atoms, more preferably a straight-chain alkylene group having 4 or more and 12 or less carbon atoms. Typically, in R... 4 When the polyurethane composition is a linear alkylene group, the viscosity tends to increase. However, in this embodiment, due to the presence of R in C and D... 4 Different types of polycarbonate diol Y are used as curing agents, thus suppressing the viscosity increase of the polyurethane composition. On the other hand, due to R... 4 It is a straight-chain alkylene group, thus further improving the strength of the resulting first resin layer 20.

[0154] Furthermore, since C and D are different, naturally, R... 4 The difference between C and D is that the absolute value of the difference between the number of carbon atoms in C and the number of carbon atoms in D is, for example, 1 or more and 8 or less, preferably 1 or more and 6 or less.

[0155] Furthermore, preferably, in C, R 4 The number of carbon atoms in D ranges from 2 to 18, and in D, R 4 The number of carbon atoms is 3 to 19, more preferably, in C, R 4 The number of carbon atoms in D ranges from 2 to 11, and in D, R 4 The number of carbon atoms is 4 to 12, more preferably, in C, R 4 The number of carbon atoms in D ranges from 3 to 11, and in D, R 4 The number of carbon atoms ranges from 4 to 12.

[0156] Particularly preferred are the following combinations of C and D.

[0157] In C, R 4 It is n-propenyl, and in D, R 4 It is n-butenyl, or

[0158] In C, R 4 It is n-butenyl, and in D, R 4 It is n-hexenyl or n-decenyl, or

[0159] In C, R 4 It is n-pentenyl, and in D, R 4 It is n-hexenyl, or

[0160] In C, R 4 It is n-hexenyl, and in D, R 4 It is n-undecenyl or n-dodecenyl, or

[0161] In C, R 4 It is an undecenyl group, and in D, R 4 It is an ortho-dodecenyl group.

[0162] m and n are independent integers of 1 or more and 46 or less. Preferably, m and n are independent integers of 1 or more and 40 or less, and more preferably, they are integers of 1 or more and 30 or less.

[0163] Furthermore, the ratio of m to n represents the ratio of C to D groups. There is no particular limitation on m / n, for example, it is 0.01 or more and 30 or less, preferably 0.02 or more and 19 or less, and more preferably 0.1 or more and 10 or less.

[0164] Furthermore, in equation (3), R 3 It is a straight-chain, branched, or cyclic alkylene group having 1 or more but less than 20 carbon atoms. Furthermore, typically, due to the preparation method, R... 3 It is a straight-chain alkylene group, more specifically an R corresponding to C or D. 4 Straight-chain alkylene groups can be exemplified by alkylene groups that are the same as C and D.

[0165] There is no particular limitation on branched alkylene groups; examples include 1-methylpropenyl, 2-methylpropenyl, 1,1-dimethylpropenyl, 1,2-dimethylpropenyl, 1,3-dimethylpropenyl, 2,2-dimethylpropenyl, 1,2,3-trimethylpropenyl, 1,1,2-trimethylpropenyl, 1,2,2-trimethylpropenyl, 1,1,3-trimethylpropenyl, 1-methylbutenyl, 2-methylbutenyl, 1,1-dimethylbutenyl, 1,2-dimethylbutenyl, 1,3-dimethylbutenyl, 1,4-dimethylbutenyl, 2,2-dimethylbutenyl, 2,3-dimethylbutenyl, 1,2,3-trimethylbutenyl, 1,1 2-Trimethylbutenyl, 1,2,2-Trimethylbutenyl, 1,3,3-Trimethylbutenyl, 1-Methylpentenyl, 2-Methylpentenyl, 3-Methylpentenyl, 2-Butyl-2-ethylpentenyl, 1-Methylhexenyl, 2-Methylhexenyl, 3-Methylhexenyl, 1-Methylheptenyl, 2-Methylheptenyl, 3-Methylheptenyl, 4-Methylheptenyl, 1-Methyloctenyl, 2-Methyloctenyl, 3-Methyloctenyl, 4-Methyloctenyl, 1-Methylnonenyl, 2-Methylnonenyl, 3-Methylnonenyl, 4-Methylnonenyl, 5-Methylnonenyl, 1-Methyldecenyl, 2-Methyldecenyl, 3-Methyldecenyl, 4-Methyldecenyl, 5-Methyldecenyl, etc.

[0166] There is no particular limitation on the cyclic alkylene group; for example, it can be a group having an alicyclic group such as a cyclopentane ring, a cyclohexane ring, a cycloheptane ring, or a cyclooctane ring. In this case, R 3 The cyclic alkylene group is bonded directly to an adjacent oxygen atom from an alicyclic group or an alkylene group having 1 to 3 carbon atoms substituted by an alicyclic group. Examples of such cyclic alkylene groups include 1,4-cyclohexanedimethylbis(methylene).

[0167] Furthermore, the polycarbonate diol Y represented by formula (3) may also contain units other than C and D. Examples of such units include esters based on branched or cyclic alkylene glycols and carbonates. Examples of alkylene compounds contained in such units include those in the aforementioned R... 1 Examples of branched or cyclic alkylene groups having 1 or more but less than 20 carbon atoms are listed.

[0168] Furthermore, in the polycarbonate diol Y represented by formula (3), there is no particular limitation on the sequence of units containing C and D. That is, polycarbonate diol Y can be a random copolymer, an alternating copolymer, or a block copolymer.

[0169] There is no particular limitation on the number average molecular weight of the polycarbonate diol Y. For example, it can be 250 or more and 4000 or less, preferably 500 or more and 3000 or less.

[0170] As described above, the curing agent with active hydrogen groups includes polycarbonate diol. However, the curing agent may also include curing agents other than polycarbonate diol. There is no particular limitation on such curing agent, and one or more compounds selected from the group consisting of polyol compounds and polyamines may be used.

[0171] In addition to the long-chain polyol compounds mentioned above, various aliphatic polyol compounds and various alicyclic or aromatic polyol compounds can also be used as polyol compounds that can be included in the curing agent.

[0172] There are no particular limitations on aliphatic polyol compounds; examples include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,5-hexanediol, 1,6-hexanediol, 2,5-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, and 1,12-dodecanediol. Alkyl glycol compounds such as alcohols, 1,13-tetrazanediol, 1,14-tetradecanediol, 1,16-hexadecanediol, 1,18-octadecanediol, 1,20-eicosenediol, 2-methyl-1,3-propanediol, neopentyl glycol, 2-butyl-2-ethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, and 2-methyl-1,8-octanediol, or glycerol, trimethylolpropane, trimethylolpropane (TMP), pentaerythritol, and dimethylolpropionic acid (DHPA).

[0173] There are no particular limitations on alicyclic polyol compounds; for example, 1,4-cyclohexanediethanol and hydrogenated bisphenol A can be cited.

[0174] There are no particular limitations on aromatic polyol compounds. Examples include hydroquinone di-β-hydroxyethyl ether (HQEE), hydroxyphenyl ether resorcinol (HER), 1,3-bis(2-hydroxyethoxybenzene), 1,4-bis(2-hydroxyethoxybenzene), bisphenol A, alkyl oxide adducts of bisphenol A, bisphenol S, alkyl oxide adducts of bisphenol S, etc.

[0175] There are no particular limitations on polyamines, but examples include hydrazine, ethylenediamine, 4,4'-methylene-bis-(2-chloroaniline) (MOCA), dimethylthiotoluenediamine (DMTDA), diethylthiotoluenediamine, diethyltoluenediamine (DETDA), trimethylenediol di(p-aminobenzoate) (TMAB), 4,4'-methylene-bis-(3-chloro-2,6-diethylaniline) (MCDEA), 4,4'-methylene-bis-(2,6-diethylaniline) (MDEA), triisopropanolamine (TIPA), p-bis(aminocyclohexyl)methane (PACM), naphthalene-1,5-diamine, xylenediamine, phenylenediamine, toluene-2,4-diamine, tert-butyltoluenediamine, and 1,2-bis(2-aminophenylthioethane).

[0176] Furthermore, when the curing agent contains curing agents other than polycarbonate diol, the proportion of polycarbonate diol in the curing agent is, for example, 10% by mass or more and less than 100% by mass, preferably 50% by mass or more and less than 95% by mass.

[0177] Furthermore, resin 23 may also be combined with one or more inorganic fillers such as titanium dioxide, kaolin, clay, talc, diatomaceous earth, calcium carbonate, calcium silicate, magnesium silicate, silicon dioxide, mica, etc.

[0178] Furthermore, if either the resin 33 of the second resin layer 30 or the resin 13 of the reinforcing fiber substrate layer 10 contains polyurethane resin P, the first resin layer 20 may not contain the aforementioned polyurethane resin P. In this case, the material of the resin 23 of the first resin layer 20 may be a combination of one or more thermosetting resins such as polyurethane resin (however, in addition to the aforementioned polyurethane resin P), epoxy resin, and acrylic resin, or thermoplastic resins such as polyamide, polyarylate, and polyester.

[0179] The resin 33 constituting the second resin layer 30 may 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 also be the same as or different from the resin 23 constituting the first resin layer 20 in type and composition. In particular, from the viewpoint of improving the durability of the second resin layer 30 and improving resin production efficiency, the resin 33 constituting the second resin layer 30 is preferably the same as the resin 23 of the first resin layer 20.

[0180] Furthermore, the second resin layer 30 preferably comprises polyurethane resin P. The second resin layer 30 constitutes the inner peripheral surface 31 of the boot-shaped press belt 1. In the boot-shaped press belt 1, the inner peripheral surface 31 is a part that is prone to damage such as cracks due to friction with the boot or bending fatigue of the boot-shaped press belt 1 when it is used. Therefore, by making the second resin layer 30 constituting the inner peripheral surface 21 of the boot-shaped press belt 1 polyurethane resin P, the durability of the boot-shaped press belt 1 is improved.

[0181] The resin 13 constituting the reinforcing fiber substrate layer 10 may 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 substrate layer 10 may also 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 production efficiency, the resin 13 constituting the reinforcing fiber substrate layer 10 may also be the same as the resin 23 of the first resin layer 20.

[0182] Furthermore, the reinforcing fiber substrate layer 10 preferably comprises polyurethane resin P. This increases the strength of the reinforcing fiber substrate layer 10 and improves the durability of the boot-shaped press belt 1.

[0183] There are no particular limitations on the size of the boot-shaped press belt 1 as described above, and it can be set appropriately according to its application.

[0184] For example, the width of the boot-shaped pressing belt 1 is not particularly limited and can be 700mm to 13500mm, preferably 2500mm to 12500mm.

[0185] Furthermore, for example, the length (circumference) of the boot-shaped pressing belt 1 is not particularly limited, and can be 150cm to 1500cm, preferably 200cm to 1100cm.

[0186] Furthermore, there is no particular limitation on the thickness of the boot-shaped pressing belt 1. For example, it can be 1.5mm to 7.0mm, and preferably 2.0mm to 6.0mm.

[0187] Furthermore, the thickness of each part of the boot-shaped press belt 1 can be different or the same.

[0188] In the boot-shaped press belt 1 according to this embodiment, at least one of the resin 13 of the reinforcing fiber substrate layer 10, the resin 23 of the first resin layer 20, and the resin 33 of the second resin layer 30 contains polyurethane resin P. Therefore, the boot-shaped press belt 1 suppresses strength imbalance between components and exhibits excellent strength.

[0189] Next, another embodiment of the boot-shaped press belt according to this embodiment will be described. Figure 2This is a cross-sectional view of a machine with a boot-shaped pressing belt according to another embodiment of the present invention. Hereinafter, the differences from the embodiment described above will be highlighted, and descriptions of identical items will be omitted.

[0190] like Figure 2 As shown, the boot-shaped press belt 1A has a plurality of drainage grooves 25 formed on the outer peripheral surface 21 of the first resin layer 20A. Because the boot-shaped press belt 1A has drainage grooves 25, more moisture can be removed from the wet paper being held when the boot-shaped press belt 1A is used.

[0191] There are no particular limitations on the shape of the drainage ditch 25; however, it is generally formed as a plurality of continuous ditches parallel to the longitudinal direction of the machine, along the boot-shaped press belt 1A. For example, the width of the ditch can be set to 0.5 mm to 2.0 mm, the depth of the ditch can be set to 0.4 mm to 2.0 mm, and the number of ditches can be set to 5 to 20 per inch. Furthermore, the cross-sectional shape of the drainage ditch 25 can be appropriately set as rectangular, trapezoidal, U-shaped, or circular in the welded area and at the bottom of the ditch where it connects to the ditch wall.

[0192] Furthermore, these drainage ditches 25 can be identical in width, depth, number, and cross-sectional shape, or they can be combined to form different shapes. Moreover, these drainage ditches 25 can form multiple discontinuous or parallel ditches along the machine's transverse direction.

[0193] In the boot-shaped press belt 1A according to this embodiment, at least one of the resin 13 of the reinforcing fiber substrate layer 10, the resin 23 of the first resin layer 20A, and the resin 33 of the second resin layer 30 contains polyurethane resin P. Therefore, the boot-shaped press belt 1A suppresses strength imbalance between components and exhibits excellent strength.

[0194] 2. Preparation method of boot-shaped pressing belt

[0195] Next, a preferred embodiment of the method for preparing the boot-shaped press belt of the present invention will be described. Figures 3-5 A simplified diagram illustrating a preferred embodiment of the method for preparing a boot-shaped press belt.

[0196] The method for preparing the boot-shaped press belt according to the present invention is a method for preparing a boot-shaped press belt for a paper machine, comprising the step of forming a resin layer by curing an isocyanate prepolymer with an isocyanate group by a curing agent having an active hydrogen group.

[0197] The above-mentioned urethane prepolymer is obtained by reacting a polyisocyanate compound containing 4,4'-methylene bis(phenyl isocyanate) (MDI) with a polyol compound containing polytetramethylene ether diol.

[0198] The curing agent mentioned above contains polycarbonate diol.

[0199] Furthermore, the method for preparing the boot-shaped press belt according to an embodiment of the present invention includes a resin layer forming step of forming a first resin layer 20, a reinforcing fiber substrate layer 10, and a second resin layer 30.

[0200] In the resin layer forming step, a resin layer is formed. Specifically, in this step, a laminate is formed having an annular and strip-shaped reinforcing fiber substrate 11 embedded in the resin 13, and a first resin layer 20 and a second resin layer 30 serving as resin layers on both sides thereof.

[0201] Such a laminate can be formed by any method, but in this embodiment, firstly, a second resin layer 30 is formed. Next, a reinforcing fiber substrate 11 is disposed on one surface of the second resin layer 30, and a resin material is coated, impregnated, and permeated into the reinforcing fiber substrate 11, thereby forming a laminate integral with the reinforcing fiber substrate layer 10 and the second resin layer 30. Then, a first resin layer 20 is formed on the surface of the reinforcing fiber substrate layer 10 facing the contact surface with the second resin layer 30.

[0202] Specifically, for example, firstly, such as Figure 3 As shown, a resin precursor layer, serving as the second resin layer 30, is formed by applying a resin material to the surface of the mandrel 110, which is coated with a release agent on the rotating surface, to a thickness of 0.8 to 3.5 mm. Next, the temperature of the resin precursor layer is raised to 40 to 140°C and pre-cured for 0.5 to 1 hour to form the second resin layer 30.

[0203] Next, a reinforcing fiber substrate 11 (not shown) is disposed on the pre-cured second resin layer 30, as follows: Figure 4 As shown, the mandrel 110 is rotated, and the resin material forming the reinforcing fiber substrate layer 10 is coated to a thickness of 0.5 to 2.0 mm, impregnating and penetrating into the reinforcing fiber substrate, and contacting the second resin layer 30, thereby forming a laminate consisting of the reinforcing fiber substrate layer 10 and the second resin layer 30.

[0204] After that, as Figure 5 As shown, resin material, which forms the first resin layer 20 while rotating the mandrel 110, is applied to and impregnated onto the surface of the reinforcing fiber substrate layer 10 to form a thickness of 1.5 to 4 mm, thus forming a resin precursor layer as the first resin layer 20. Next, the resin precursor layer is heated and cured at 70 to 140°C for 2 to 20 hours to form a laminate of the first resin layer 20, the reinforcing fiber substrate layer 10, and the second resin layer 30.

[0205] Furthermore, the resin material can be applied by any method, but in this embodiment, the resin material is discharged from the injection molding nozzle 130 while the mandrel 110 is rotated, and the supplied resin material is uniformly applied using the coating rod 120 at the same time.

[0206] In this process, at least one of the resin 13 of the reinforcing fiber substrate layer 10, the resin 23 of the first resin layer 20, and the resin 33 of the second resin layer 30 forms a polyurethane resin P. As described above, when polycarbonate diol is mixed with a urethane prepolymer obtained by reacting a polyisocyanate compound containing 4,4'-methylene bis(phenyl isocyanate) (MDI) with a polyol compound containing polytetramethylene ether diol, the viscosity increase of the polyurethane composition (resin material) can be suppressed. Therefore, a polyurethane resin layer with excellent strength and suppressing strength imbalances between components can be formed.

[0207] Furthermore, there are no particular restrictions on the heating method; for example, far-infrared heaters can be used.

[0208] The obtained laminate is ground or polished on the outer peripheral surface 21 and the inner peripheral surface 31 as needed, and the ends in the width direction are appropriately cut and adjusted to obtain the boot-shaped press belt 1. The boot-shaped press belt 1 is prepared through the above steps.

[0209] Furthermore, in the case of preparing the boot-shaped press belt 1A, the laminate formed in the above-mentioned resin layer forming step may also form a drainage groove 25 on the outer peripheral surface 21 as shown in the following steps.

[0210] The drainage ditch 25 can be formed by any method, for example, grinding or polishing the outer surface of the laminate obtained above to give it the required thickness of the boot-shaped press belt 1 (not shown), and then, while rotating the mandrel 110, bringing the ditch processing device equipped with multiple disc-shaped rotating blades into contact with the outer peripheral surface 21 to form the drainage ditch 25.

[0211] Furthermore, the method for preparing the boot-shaped press belt in the above embodiments has been described as a method for preparing a mandrel (single roller). However, as another embodiment, a two-roller preparation method can be used as follows. First, a ring-shaped reinforcing fiber substrate 11 is suspended on two parallel rollers, and resin is applied, impregnated, and laminated onto the reinforcing fiber substrate 11 to form a second resin layer 30 together with the reinforcing fiber substrate layer 10. Next, it is reversed, and a first resin layer 20 is formed on the surface of the reversed reinforcing fiber substrate layer 10. Thus, the boot-shaped press belt 1 can be obtained. Furthermore, the formation order of each resin layer can be arbitrary.

[0212] Although the present invention has been described in detail above based on preferred embodiments, the present invention is not limited thereto. Each component may be replaced with any component that can perform the same function, or any component may be added.

[0213] Example

[0214] The present invention will be described in more detail below through embodiments, but the present invention is not limited to these embodiments.

[0215] 1. Preparation of boot-shaped press belt and polyurethane sheet samples

[0216] Before preparing the boot-shaped press belt, polycarbonate diol as shown in Table 1, polytetramethylene ether diol as shown in Table 2, and resin materials (polyurethane compositions) having the compositions of Examples 1-3 and Comparative Examples 1-4 as shown in Table 3 were first prepared. Furthermore, for all resin materials, urethane prepolymer and curing agent were added to achieve a [H] / [NCO] ratio of 0.95.

[0217] Next, boot-shaped press belts were prepared using the resin materials of Examples 1-3 and Comparative Examples 1-4 by the following method.

[0218] On the surface of a rotatable mandrel with a diameter of 1500 mm, the resin materials of Examples 1-3 and Comparative Examples 1-4 are applied to a thickness of 1.4 mm through an injection molding nozzle parallel to the rotation axis of the mandrel while the mandrel is rotating, to form an uncured bootside resin layer (second resin layer). The mandrel is then rotated continuously at room temperature for 10 minutes, heated to 140°C by a heating device mounted on the mandrel, and the bootside resin layer is pre-cured at 140°C for 1 hour.

[0219] Next, the warp yarns are clamped by the weft yarns, and a seamless layer of weft and warp yarn intersections is arranged on the outer periphery of the resin layer on the boot side. This is achieved by bonding a grid-like material with a polyurethane resin adhesive, aligning the weft yarns along the axial direction of the mandrel. The weft yarns of the grid-like material are 5000 dtex multifilament twisted polyethylene terephthalate (PET) fibers, and the warp yarns are 550 dtex multifilament PET fibers. Furthermore, the warp yarn density is 1 thread / cm, and the weft yarn density is 4 threads / cm.

[0220] Next, 6700 dtex multifilaments of polyethylene terephthalate fiber are spirally wound around the outer periphery of the lattice material at a spacing of 30 lines / 5 cm to form a filament winding layer. These lattice materials and the filament winding layer form a reinforcing fiber substrate. Then, a resin material identical to that used in the bootside resin layer is applied to seal the gaps in the reinforcing fiber substrate (the resin material used in Examples 1-3 and Comparative Examples 1-4), forming a laminate consisting of the reinforcing fiber substrate layer and the bootside resin layer.

[0221] Next, from above the reinforcing fiber substrate layer, while rotating the mandrel, a resin material (the same resin material as the reinforcing fiber substrate layer and the boot side resin layer, the resin material of Examples 1-3 and Comparative Examples 1-4) is applied to a thickness of about 2.5 mm through an injection molding nozzle that can move parallel to the rotation axis of the mandrel, forming an uncured felt side resin layer (first resin layer).

[0222] Next, the mandrel is rotated and left at room temperature for 40 minutes. Then, it is heated to 140°C using a heating device mounted on the mandrel, and each resin layer is cured at 140°C for 4 hours. This forms a laminate consisting of an integral felt-side resin layer, a reinforcing fiber substrate layer, and a boot-side resin layer.

[0223] Next, the felt contact surface of the resin layer on the felt side is ground to make the total thickness 5.2 mm, thereby obtaining a laminate.

[0224] Boot-shaped press belts according to Examples 1-3 and Comparative Examples 1-4 were obtained through the above steps. The hardness of the obtained boot-shaped press belts was evaluated. Furthermore, in order to evaluate the breaking strength and unevenness in the tensile test, polyurethane sheet samples with a thickness of 1.0 mm were cut from any 20 locations of the resin layer on the felt side.

[0225] 2. Evaluation

[0226] 2.1. Prepolymer viscosity

[0227] The viscosities of the resin materials used in Examples 1-3 and Comparative Examples 1-4 were measured. For the viscosity of the prepolymer, a Type B viscometer (Toki Sangyo Co., Ltd., product name: TVB-10H) was used to measure the viscosity of the prepolymer at temperatures of 50°C and 80°C. Furthermore, using an H3 rotor, the rotational speeds were measured at 50 rpm at 200–2000 mPa·s and at 5 rpm at 2000–20000 mPa·s.

[0228] 2.2. Hardness Evaluation

[0229] The hardness of the outer peripheral surface of the boot-shaped press belts according to Examples 1-3 and Comparative Examples 1-4 was measured. Specifically, the surface hardness of the resin layer on the felt side was measured using a spring hardness tester type A according to JIS K 6301:1995.

[0230] 2.3. Evaluation of fracture strength by tensile test

[0231] For fracture strength, a universal tensile testing machine was used as the testing machine, with dumbbell No. 3 specimens as specified in JIS K 6251 as the sample shape, and the fracture strength was measured at a tensile speed of 500 mm / min. The stress (MPa) at specimen fracture was evaluated. Each example and comparative example was measured 20 times, and the average value is expressed.

[0232] 2.4. Evaluation of Uneven Fracture Strength

[0233] The unevenness of fracture strength was evaluated by calculating the standard deviation of the measured fracture strength values ​​from 20 tensile tests.

[0234] The above evaluation results, along with the composition of the resin materials of Examples 1-3 and Comparative Examples 1-4, are shown in Table 3. In Table 3, “MDI” represents 4,4'-methylenebis(phenyl isocyanate), “PPDI” represents p-phenylene diisocyanate, “TDI” represents a mixture of 2,4-toluene diisocyanate and 2,6-toluene diisocyanate, “BD” represents 1,4-butanediol, and “DMTDA” represents dimethylthiotoluene diamine.

[0235] Furthermore, regarding the number-average molecular weight of the polycarbonate diols in Table 1, the number-average molecular weight was calculated based on the obtained hydroxyl value and formula (II) above, while measuring the hydroxyl value of each polycarbonate diol. The same applies to the polytetramethylene ether diols in Table 2.

[0236] Table 1

[0237]

[0238] Table 2

[0239] Polytetramethylene ether diol Number average molecular weight Hydroxyl value (mg KOH / g) PTMG1 648 173.1 PTMG2 1039 108.0

[0240] Table 3

[0241]

[0242]

[0243] As shown in Table 3, compared with the boot-shaped press belts according to Comparative Examples 1, 2, and 4, the boot-shaped press belts according to Examples 1-3 suppress the strength imbalance between components and exhibit excellent strength. The boot-shaped press belt according to Comparative Example 3, which does not use polycarbonate, suppresses the strength imbalance between components, but its strength is significantly lower than that of the boot-shaped press belts according to Examples 1-3.

[0244] Furthermore, the boot-shaped press belt of Comparative Example 4, which uses various linear aliphatic polycarbonate diols as urethane prepolymers, exhibits excellent strength, but there is a significant imbalance in strength between its components. Therefore, the boot-shaped press belt of Comparative Example 4 may fail to improve its durability, potentially starting with the weakest parts.

Claims

1. A boot-shaped press belt for a paper machine, characterized in that, Having at least one resin layer, The aforementioned resin layer comprises a polyurethane resin containing isocyanate groups cured by a curing agent with active hydrogen groups onto a urethane prepolymer. The above-mentioned urethane prepolymer is obtained by reacting a polyisocyanate compound containing 4,4'-methylene bis(phenyl isocyanate) with a polyol compound composed of polytetramethylene ether diol. The above-mentioned curing agent contains more than 50% by mass of polycarbonate diol; The aforementioned resin layer constitutes the outer peripheral surface of the aforementioned boot-shaped press belt, and has a layer containing the aforementioned polyurethane resin.

2. The boot-shaped press belt according to claim 1, characterized in that, The curing agent described above contains polycarbonate diol X containing one or more units A represented by the following formula (1). Chemical Formula 1: In equation (1), R 1 It is a branched alkylene group having 3 or more but less than 20 carbon atoms.

3. The boot-shaped press belt according to claim 2, characterized in that, R 1 The group consisting of 3-methylpentenyl, 2,2-dimethylpropenyl, 2-methyloctenyl, 2-butyl-2-ethylpropenyl and 2,2,4-trimethyl-1,6-hexenyl is selected.

4. The boot-shaped press belt according to claim 2, characterized in that, The aforementioned polycarbonate diol X further comprises one or more units B represented by the following formula (2), Chemical formula 2: In equation (2), R 2 It is a straight-chain alkylene group having 1 or more but less than 20 carbon atoms.

5. The boot-shaped press belt according to claim 1, characterized in that, The above-mentioned curing agent contains one or more polycarbonate diols Y represented by the following formula (3), Chemical formula 3: HO-Cm-Dn-R3OH In equation (3), C and D are distinct units represented by the following equation (4). Chemical formula 4: R 3 It is a straight-chain, branched, or cyclic alkylene group having 1 or more but less than 20 carbon atoms. n and m are independent integers greater than 1 and less than 46. In equation (4), R 4 It is a straight-chain alkylene group having 1 or more but less than 20 carbon atoms.

6. The boot-shaped press belt according to claim 5, characterized in that, In the above formula (3), In C, R 4 It is n-propenyl, and in D, R 4 It is n-butenyl, or In C, R 4 It is n-butenyl, and in D, R 4 It is n-hexenyl or n-decenyl, or In C, R 4 It is n-pentenyl, and in D, R 4 It is n-hexenyl, or In C, R 4 It is n-hexenyl, and in D, R 4 It is n-undecenyl or n-dodecenyl, or In C, R 4 It is an undecenyl group, and in D, R 4 It is an ortho-dodecenyl group.

7. The boot-shaped press belt according to any one of claims 1 to 6, characterized in that, The aforementioned resin layer constitutes the inner circumferential surface of the aforementioned boot-shaped press belt, and has a layer containing the aforementioned polyurethane resin.

8. A method for preparing a boot-shaped press belt for a paper machine, characterized in that, The process includes the step of curing an isocyanate-containing urethane prepolymer with an isocyanate group by a curing agent having active hydrogen groups to form a resin layer constituting the outer peripheral surface of the aforementioned boot-shaped press belt. The above-mentioned urethane prepolymer is obtained by reacting a polyisocyanate compound containing 4,4'-methylene bis(phenyl isocyanate) with a polyol compound composed of polytetramethylene ether diol. The curing agent mentioned above contains more than 50% by mass of polycarbonate diol.

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