JP3803106B2 - Papermaking belt and method for producing papermaking belt - Google Patents

Description

  The present invention relates to a papermaking belt. More specifically, the present invention relates to an improvement in polyurethane in a papermaking belt in which a reinforcing substrate and a thermosetting polyurethane are integrated. The present invention also relates to an improvement in a method for manufacturing a papermaking belt in which a reinforcing base material and a thermosetting polyurethane are integrated. In particular, the present invention is used for shoe press belts, calender belts and sheet transfer belts used in the paper industry.

  In recent years, in the press part of the papermaking process, in order to enhance the dewatering effect of wet paper, one side of the wet paper placed on the felt running at high speed is pressed with a press roll, and the other side is passed through an endless belt. A so-called shoe press that dehydrates wet paper by pressurizing with a pressure shoe has become widespread. In shoe presses, a belt formed by integrating a reinforcing base material and a thermosetting polyurethane into an endless structure has been conventionally used. In recent years, the use of an elastic belt as described above has also been studied in a calendar process for smoothing the surface of paper and imparting gloss. Furthermore, in the case of making paper at high speed, it has been studied to use the elastic belt as described above for sheet transfer for preventing paper breakage and stably transporting wet paper. As a typical structure of such a papermaking belt, those in which both sides of a base fabric are covered with an elastic material are disclosed in Japanese Utility Model Laid-Open No. 59-54598, Japanese Patent No. 2889341, Japanese Patent No. 3045975, and the like. . Another typical structure is disclosed in Japanese Patent No. 2542250 and the like in which a reinforcing yarn is embedded in an elastic material.

  As an elastic material for a papermaking belt, thermosetting polyurethane obtained by mixing and curing a urethane prepolymer and a curing agent is disclosed in Japanese Patent No. 2889341, Japanese Patent Laid-Open No. 6-287885, Japanese Patent No. 3045975, and Japanese Patent No. 3053374. No. 1, JP-A-11-247086 and the like, and the thermosetting polyurethane used for papermaking belts is 4,4′-methylene as a curing agent. -Bis- (2-chloroaniline) (hereinafter referred to as “MOCA”) was used.

Conventionally, in a shoe press, severe bending and pressurization of the belt are repeated between the press roll and the pressure shoe, so that cracking in the polyurethane constituting the belt has been a major problem. . This crack mainly occurs on the outer peripheral surface of the belt in contact with the felt or paper. Further, in a dewatering press belt used in a press part, in order to increase dewatering efficiency, a drainage groove is generally formed on the outer peripheral surface thereof. However, the crack is particularly generated from a bottom edge and an upper edge of the drainage groove. It was easy to occur. Cracks that have occurred once tend to develop into large cracks as the belt is used. When the crack progresses, the lubricating oil between the inner peripheral surface of the belt and the pressure shoe leaks to the outside and adversely affects the paper or causes delamination of the belt. Thus, the occurrence and development of cracks cause a reduction in the life of the belt. For this reason, in papermaking belts used in shoe presses and the like, there has been a strong demand for suppressing the occurrence of cracks and the development of cracks. Furthermore, apart from the occurrence of cracks, delamination may occur due to weak adhesive strength between the base fabric and polyurethane, and it has been anxious to prevent delamination between the base fabric and polyurethane.
Japanese Utility Model Publication No.59-54598 Japanese Patent No. 2889341 Japanese Patent No. 3045975 Japanese Patent No. 2542250 Japanese Patent Laid-Open No. 6-287885 Japanese Patent No. 3053374 Japanese Patent Laid-Open No. 11-247086

  The present invention solves the above-described problems, and provides a papermaking belt that can prevent the occurrence of cracks in a papermaking belt in which a reinforcing base and a thermosetting polyurethane are integrated. Another object of the present invention is to suppress the development of a crack in a papermaking belt in which a reinforcing base material and a thermosetting polyurethane are integrated, even if a crack occurs in the papermaking belt. It is to provide a papermaking belt that can be used. Another object of the present invention is to make a papermaking belt in which a reinforcing base material and a thermosetting polyurethane are integrated, and for papermaking which can suppress the occurrence of delamination between the reinforcing base material and the polyurethane. To provide a belt. Another object of the present invention is to provide a method for producing the papermaking belt described above.

The papermaking belt according to the present invention comprises a reinforcing base material and a thermosetting polyurethane integrated together as described in claim 1 , wherein the reinforcing base material is embedded in the polyurethane, In the papermaking belt comprising the outer polyurethane bonded to the outer peripheral surface of the inner polyurethane, the inner polyurethane and the outer polyurethane are urethane prepolymer having an isocyanate group at the terminal and active at the terminal. Each of the compositions formed from a composition containing a curing agent having a hydrogen group and forming the inner polyurethane has an equivalent ratio of the active hydrogen group (H) of the curing agent to the isocyanate group (NCO) of the urethane prepolymer. The urethane prepolymer and the curing agent are mixed in such a ratio that (H / NCO) is 0.85 ≦ H / NCO <1. In the composition forming the outer polyurethane, the urethane prepolymer and the curing agent are mixed in a ratio such that the equivalent ratio (H / NCO) is 1 <H / NCO <1.15. It is a papermaking belt. In the present invention, the equivalent ratio is a stoichiometric equivalent ratio.

The papermaking belt according to the present invention, as described in claim 2, in the invention according to the first aspect, the adhesive surface of the polyurethane of the outer polyurethane of the inner, inside the reinforcing substrate The urethane prepolymer of the inner polyurethane contains a urethane prepolymer obtained by reacting a polyol and diphenylmethane diisocyanate (MDI), and the urethane prepolymer of the outer polyurethane is composed of a polyol and tolylene diisocyanate. It is a papermaking belt containing a urethane prepolymer obtained by reacting with (TDI).

The papermaking belt according to the present invention, as described in claim 3, in the invention of claim 2, wherein the polyurethane of the inner, or 50 wt% of the curing agent is a papermaking belt is a polyol.

The papermaking belt according to the present invention, as described in claim 4, in the invention of claim 2 or 3, wherein the reinforcing base material, for papermaking are those containing a multiple-woven has been woven It is a belt.

Moreover, the papermaking belt according to the present invention is as described in claim 5 , in the invention according to any one of claims 1 to 4 , the outer polyurethane adheres to the outer peripheral surface of the inner polyurethane. And a papermaking belt formed from a composition comprising a urethane prepolymer having an isocyanate group at a terminal and a curing agent containing dimethylthiotoluenediamine, which constitutes the outer peripheral surface of the papermaking belt. .

The papermaking belt according to the present invention, as described in claim 6, in the invention described in any one of claims 1 to 4, wherein the polyurethane has an inner polyurethane, the outer circumferential surface of the polyurethane of the inner And a polyurethane preliminarily having an isocyanate group at a terminal thereof. The polyurethane constituting the outer peripheral surface of the papermaking belt is located on the outer side of the outer polyurethane. And a curing agent containing dimethylthiotoluenediamine, a papermaking belt.

Further, the papermaking belt according to the present invention is as described in claim 7 , in the invention according to claim 6 , the polyurethane composition constituting the outer peripheral surface is an active hydrogen group (H) of the curing agent. The urethane prepolymer and the curing agent are mixed in such a ratio that the equivalent ratio (H / NCO) of the urethane prepolymer to the isocyanate group (NCO) of the urethane prepolymer is 1 <H / NCO <1.15. It is a papermaking belt.

The papermaking belt according to the present invention, as described in claim 8, in the invention according to any one of claims 1 to 7 as the polyurethane is cured at a temperature of 120 ° C. to 140 ° C. This is a papermaking belt.

The papermaking belt according to the present invention, as described in claim 9, in the invention of any one of claims 1-8, a papermaking belt which drainage grooves on the outer peripheral surface is formed.

Further, according to the method for manufacturing a papermaking belt according to the present invention, the reinforcing substrate and the thermosetting polyurethane are embedded by embedding the reinforcing substrate in the thermosetting polyurethane as described in claim 10. A method for producing a papermaking belt comprising an inner polyurethane and an outer polyurethane bonded to the outer peripheral surface of the inner polyurethane, wherein the inner polyurethane is a urethane prepolymer having an isocyanate group at the terminal And a curing agent having an active hydrogen group at the end, the value of the equivalent ratio (H / NCO) of the active hydrogen group (H) of the curing agent to the isocyanate group (NCO) of the urethane prepolymer is 0.85 ≦ First, a liquid mixture obtained by mixing a urethane prepolymer and a curing agent at a ratio of H / NCO <1 is cured at a temperature of 70 ° C. to 100 ° C. and molded. A urethane prepolymer having an isocyanate group at the terminal and a curing agent having an active hydrogen group at the terminal, and an equivalent ratio of the active hydrogen group (H) of the curing agent to the isocyanate group (NCO) of the urethane prepolymer. A second step of applying a mixed liquid in which a urethane prepolymer and a curing agent are mixed at a ratio of (H / NCO) of 1 <H / NCO <1.15 on the outer peripheral surface of the inner polyurethane; The whole is heated to a temperature of 120 ° C to 140 ° C to cure the mixed liquid applied on the outer peripheral surface of the inner polyurethane to form the outer polyurethane, and the inner polyurethane and the outer polyurethane are bonded and integrated. And a third step of manufacturing the papermaking belt.

The paper manufacturing belt manufacturing method according to the present invention is as described in claim 11 , wherein in the invention according to claim 10 , the inner polyurethane is provided on the one side of the reinforcing base. From the other side of the reinforcing base, the inner polyurethane is impregnated into the reinforcing base from the other side of the reinforcing base. It is a manufacturing method of the papermaking belt which is impregnated to the position.

In the papermaking belt manufacturing method according to the present invention, as described in claim 12 , in the invention described in claim 11 , the reinforcing base material includes a multi-woven fabric. It is a manufacturing method of the belt.

A papermaking belt manufacturing method according to the present invention, as described in claim 13 , is the invention according to claim 10 , wherein on the outer peripheral surface of the inner polyurethane before or after the inner polyurethane is cured. It is a manufacturing method of the papermaking belt including the process of winding the said reinforcement base material around.

  The papermaking belt according to the present invention is formed of a composition comprising a urethane prepolymer having an isocyanate group at the terminal and a curing agent containing dimethylthiotoluenediamine in the polyurethane constituting the outer peripheral surface, The generation of cracks could be prevented. Further, the papermaking belt according to the present invention is formed of a composition comprising a urethane prepolymer having an isocyanate group at a terminal and a curing agent having an active hydrogen group at a terminal in the polyurethane constituting the outer peripheral surface, In the composition, the ratio of the equivalent ratio (H / NCO) of the active hydrogen group (H) of the curing agent to the isocyanate group (NCO) of the urethane prepolymer is 1 <H / NCO <1.15. Since the urethane prepolymer and the curing agent are mixed, it is possible to prevent the generated crack from progressing even if the crack occurs in the papermaking belt. In the papermaking belt according to the present invention, the composition forming the inner polyurethane has an equivalent ratio (H / NCO) of the active hydrogen group (H) of the curing agent and the isocyanate group (NCO) of the urethane prepolymer. The composition in which the urethane prepolymer and the curing agent are mixed at a ratio of 0.85 ≦ H / NCO <1, and the composition forming the outer polyurethane has an equivalent ratio (H / NCO) value. Since the urethane prepolymer and the curing agent were mixed at a ratio of 1 <H / NCO <1.15, it was possible to suppress the occurrence of delamination between the reinforcing base material and the polyurethane.

  FIG. 1 shows an example of a shoe press apparatus used in a press part of a paper making process. In FIG. 1, a flexible cylindrical dehydrating press belt 2 is provided below the press roll 1. A felt 3 and a wet paper web 4 are passed between the belt 2 and the press roll 1. The outer peripheral surface of the belt 2 and the felt 3 are in direct contact. A pressure shoe 5 is pressed against the inner peripheral surface of the belt 2 toward the press roll side. Lubricating oil is supplied between the pressure shoe 5 and the belt 2 in order to make the belt 2 run smoothly. The belt 2 travels while sliding on the pressure shoe 5 due to friction with the felt 3. The surface of the pressure shoe 5 has a concave shape corresponding to the surface of the press roll 1. A wide pressure dewatering portion P is formed between the press roll 1 and the pressure shoe 5. The wet paper web 4 is dehydrated by the pressure dehydration unit.

  FIG. 2 is a partial cross-sectional view showing an example of the belt 2. This belt is endless, and is formed by integrating a base fabric 6 serving as a reinforcing base and a thermosetting polyurethane 7. The base fabric 6 is made of organic fibers such as polyamide and polyester. The base fabric 6 is impregnated and coated with a single layer of polyurethane 7. The outer peripheral surface and inner peripheral surface of the belt are made of polyurethane 7.

  In order to manufacture the belt shown in FIG. 2, an endless base fabric 6 having a relatively coarse opening that allows liquid polyurethane to pass therethrough is used as a reinforcing substrate. Here, a plain weave base cloth of 10 to 100 mesh can be used as the rough base cloth. The mesh is the number of yarns per inch width. Then, the base fabric 6 is arranged on the mandrel with a gap between the mandrel and the polyurethane 7 is poured from above, so that the base fabric 6 and the polyurethane 7 are integrated, and the base fabric 6 becomes the polyurethane. The papermaking belt embedded in 7 can be manufactured.

  FIG. 3 shows an example in which reinforcing yarns 8 and 9 are used as reinforcing base materials in place of the belt base fabric 6 shown in FIG. In the belt shown in FIG. 3, the reinforcing yarns 8 and 9 are embedded in a thermosetting polyurethane 7 composed of a single layer. The reinforcing substrate is composed of a yarn 8 in the belt running direction (hereinafter referred to as “MD direction”) and a yarn 9 in a direction perpendicular to the yarn 8 (hereinafter referred to as “CMD direction”). A large number of MD-direction yarns 8 and CMD-direction yarns 9 are arranged at almost equal intervals. As the material for the yarn, for example, polyamide, aromatic polyamide, polyester, or the like can be used. The belt shown in FIG. 3 can be manufactured by placing the yarns 8 and 9 in the longitudinal and lateral directions with a gap between the mandrel and the mandrel, and pouring the polyurethane 7 from above. That is, it is possible to manufacture a papermaking belt in which the reinforcing base material using the reinforcing yarns 8 and 9 and the polyurethane 7 are integrated, and the reinforcing base material using the reinforcing yarns 8 and 9 is embedded in the polyurethane 7. it can.

  4 to 6 show a structure in which the polyurethane 7 of the belt shown in FIG. 2 is composed of two layers.

  In FIG. 4, a base fabric 6 is embedded in a polyurethane layer 10 constituting an inner peripheral surface, and a polyurethane layer 11 constituting an outer peripheral surface is further coated thereon to be integrated. In order to manufacture the belt shown in FIG. 4, the base fabric 6 having a relatively coarse mesh is disposed on the mandrel with a gap between the mandrel and the mandrel according to the belt manufacturing method of FIG. The polyurethane 10 is poured. By pouring the polyurethane 10 from above, the base fabric 6 and the polyurethane 10 are integrated, and a polyurethane layer in which the base fabric 6 is embedded in the polyurethane 10 is formed. And it can manufacture by coating the polyurethane layer 11 which comprises an outer peripheral surface from it further.

The belt shown in FIG. 5 is formed by impregnating and covering two layers of polyurethane 12 and 13 from both sides of the base fabric 6 so that the base fabric 6 and the polyurethane 12 and 13 are integrated. , 13 is obtained. When manufacturing this belt, the polyurethane layer 12 constituting the inner peripheral surface is coated from the top of the base fabric 6 whose front and back are reversed, and then the back and front of the base fabric is reversed, and further the polyurethane layer constituting the outer peripheral surface 13 is coated. In this case, as the base fabric 6 as the reinforcing base material, a fabric that is fine enough to prevent liquid polyurethane from passing therethrough is used. As the fine base fabric, a multi-woven base fabric having an air permeability of 200 to 20 cm ³ / sec / cm ² can be used.

  As another manufacturing method, after molding the polyurethane layer 12 constituting the inner peripheral surface on the mandrel, by winding the base fabric 6 on the surface and further coating the polyurethane layer 13 constituting the outer peripheral surface from above, The base fabric 6 and the polyurethanes 12 and 13 are integrated to obtain a papermaking belt in which the base fabric 6 is embedded in the polyurethanes 12 and 13.

  In FIG. 6, the polyurethane layer 14 constituting the inner peripheral surface is covered and integrated under the polyurethane layer 15 constituting the outer peripheral surface in which the base fabric 6 is embedded. In order to manufacture this belt, the polyurethane layer 15 constituting the outer peripheral surface in which the base fabric is embedded is formed in accordance with the belt manufacturing method of FIG. 2, and the inner peripheral surface is subsequently formed on the inner peripheral surface. The polyurethane layer 14 is coated. As another method, a polyurethane layer 14 constituting an inner peripheral surface is previously formed on a mandrel, and a polyurethane layer 15 constituting an outer peripheral surface in which a base fabric is embedded in accordance with the belt manufacturing method of FIG. Is molded.

  FIGS. 7 to 9 correspond to the examples shown in FIGS. 4 to 6, respectively, and show examples in which the reinforcing yarns 8 and 9 are used as the reinforcing base instead of the base cloth 6.

  In order to manufacture the belt shown in FIG. 7, the polyurethane layer 16 constituting the inner peripheral surface in which the reinforcing yarns 8 and 9 are embedded is formed in accordance with the manufacturing method of the belt of FIG. What is necessary is just to coat the polyurethane layer 17 to comprise.

  In order to manufacture the belt shown in FIG. 8, after forming the polyurethane layer 18 constituting the inner peripheral surface on the mandrel, the yarns 8 and 9 are wound on the surface in the vertical and horizontal directions, and the outer peripheral surface is further formed thereon. What is necessary is just to coat the polyurethane layer 19 which comprises.

  To manufacture the belt shown in FIG. 9, the polyurethane layer 21 constituting the outer peripheral surface in which the reinforcing yarns 8 and 9 are embedded is formed in accordance with the method of manufacturing the belt of FIG. 3, and further on the inner peripheral surface, Later, the polyurethane layer 20 constituting the inner peripheral surface is coated. As another method, after forming the polyurethane layer 20 constituting the inner peripheral surface on the mandrel in advance, the outer peripheral surface in which the reinforcing yarns 8 and 9 are embedded according to the belt manufacturing method of FIG. The polyurethane layer 21 to be formed is molded.

  The outer peripheral surface of each belt shown in FIGS. 2 to 9 is made of polyurethane. The polyurethane layers 7, 11, 13, 15, 17, 19, and 21 constituting the outer peripheral surface include a urethane prepolymer having an isocyanate group (NCO) at the terminal and a curing agent having an active hydrogen group (H) at the terminal. Formed from the containing composition. A urethane prepolymer is obtained by reacting a polyol and a phenylene isocyanate derivative.

  The polyol for obtaining the urethane prepolymer of polyurethane 7, 11, 13, 15, 17, 19, 21 constituting the outer peripheral surface is selected from polyether polyol and polyester polyol. Examples of the polyether polyol include polyethylene glycol (PEG), polypropylene glycol (PPG), and polytetramethylene glycol (PTMG). Examples of the polyester polyol include polycaprolactone ester, polycarbonate, polyethylene adipate, polybutylene adipate, and polyhexene adipate. These can be used alone or in admixture or polymerization of two or more kinds, and these modified products can also be used.

  Examples of phenylene isocyanate derivatives for obtaining urethane prepolymers of polyurethanes 7, 11, 13, 15, 17, 19, and 21 constituting the outer peripheral surface include tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), and m-xylene. Examples thereof include diisocyanate (m-XDI) and naphthalene diisocyanate (NDI). These can be used alone or in admixture of two or more.

  As a curing agent for the polyurethane 7, 11, 13, 15, 17, 19, and 21 constituting the outer peripheral surface, a curing agent such as a polyol, aromatic diol, or aromatic diamine is generally used. As the polyol-based curing agent, polytetramethylene glycol (PTMG), polypropylene glycol (PPG), or the like can be used. Moreover, hydroquinone di (beta-hydroxyethyl) ether (HQEE) etc. can be used as an aromatic diol type hardening | curing agent. As the aromatic diamine-based curing agent, 4,4′-methylene-bis- (2-chloroaniline) (MOCA), trimethylene-bis (4-aminobenzoate) (CUA-4), diethyltoluenediamine (DETDA), dimethylthiotoluenediamine (DMTDA), etc. can be used. Among these, as one feature of the present invention, it is preferable to use a curing agent containing dimethylthiotoluenediamine which is a kind of aromatic diamine-based curing agent. As dimethylthiotoluenediamine, 3,5-dimethylthio-2,4-toluenediamine represented by Formula 1 can be used.

  Further, 3,5-dimethylthio-2,6-toluenediamine represented by Formula 2 can be used as dimethylthiotoluenediamine.

  Moreover, 3,5-dimethylthio-2,4-toluenediamine or 3,5-dimethylthio-2,6-toluenediamine can be used alone or as a mixture. A particularly preferred curing material is a mixture of 3,5-dimethylthio-2,4-toluenediamine and 3,5-dimethylthio-2,6-toluenediamine, which is commercially available as “ETHACURE 300” from Albemarle. .

  When the curing agent for polyurethane 7, 11, 13, 15, 17, 19, 21 constituting the outer peripheral surface contains the dimethylthiotoluenediamine, a polyol-based, aromatic diol-based, aromatic diamine-based, etc. One type or two or more types of curing agents may be mixed. The content of the dimethylthiotoluenediamine in the curing agent of polyurethane 7, 11, 13, 15, 17, 19, 21 constituting the outer peripheral surface is 50% or more of the number of active hydrogen groups (H) of the curing agent. It is preferable to occupy. The polyurethane 7, 11, 13, 15, 15, 17 constituting the outer peripheral surface of the belt is obtained by containing dimethylthiotoluenediamine as the curing agent of the polyurethane 7, 11, 13, 15, 17, 19, 21 constituting the outer peripheral surface. , 19 and 21 can be prevented from cracking.

  From another point of view, the polyurethane layers 7, 11, 13, 15, 17, 19, and 21 constituting the outer peripheral surface are formed by the active hydrogen group (H) of the curing agent and the isocyanate group (NCO) of the urethane prepolymer. The urethane prepolymer and the curing agent are mixed in such a ratio that the value of the equivalent ratio (H / NCO) is 1 <H / NCO <1.15. By adopting such a configuration, even if a small crack occurs in the polyurethane 7, 11, 13, 15, 17, 19, 21 that constitutes the outer peripheral surface of the belt, the generated crack can be developed into a large crack. Can be suppressed. The polyurethane layers 7, 11, 13, 15, 17, 19, and 21 constituting the outer peripheral surface are urethanes at a ratio such that the equivalent ratio (H / NCO) value is 1.01 ≦ H / NCO ≦ 1.14 It is also possible to mix the prepolymer and the curing agent. In such a case, even if a small crack is generated, it is possible to prevent the generated crack from developing into a large crack. When the H / NCO value of the polyurethanes 7, 11, 13, 15, 17, 19, and 21 constituting the outer peripheral surface is 1 or less, a large crack is likely to develop when a crack occurs. On the other hand, when the H / NCO value of polyurethane 7, 11, 13, 15, 17, 19, 21 constituting the outer peripheral surface is 1.15 or more, the polyurethane becomes brittle and cracks are likely to occur.

  Polyurethanes 7, 11, 13, 15, 17, 19, and 21 constituting the outer peripheral surface use a curing agent containing dimethylthiotoluenediamine as a curing agent, and active hydrogen groups (H) of the curing agent and a urethane prepolymer. The outer peripheral surface of the belt is formed by mixing the urethane prepolymer and the curing agent at a ratio such that the value of the equivalent ratio (H / NCO) to the isocyanate group (NCO) of 1 <H / NCO <1.15. It is possible to suppress the occurrence of cracks in the polyurethane 7, 11, 13, 15, 17, 19, and 21, and even if a small crack occurs, it is possible to prevent the generated crack from developing into a large crack. it can. The content of dimethylthiotoluenediamine in the curing agent preferably occupies 50% or more of the number of active hydrogen groups (H) in the curing agent. The equivalent ratio (H / NCO) is preferably such that the urethane prepolymer and the curing agent are mixed at a ratio of 1.01 ≦ H / NCO ≦ 1.14.

  In order to increase the dewatering efficiency, the belt shown in FIGS. 2 to 9 is preferably formed with a large number of drain grooves 22 along the running direction of the belt as shown in FIG. According to the present invention, the occurrence of cracks in the papermaking belt and the development of cracks can be suppressed by the above configuration. Therefore, even if the drainage groove 22 is formed on the outer peripheral surface of the belt, Generation of cracks from the edge can be suppressed. A number of blind holes may be provided on the outer peripheral surface of the belt instead of the drain groove 22 or together with the drain groove 22.

  4 to 9, the polyurethane layer excluding the polyurethane layers 7, 11, 13, 15, 17, 19, and 21 constituting the outer peripheral surface is only one layer, but this outer peripheral surface is configured. The polyurethane layers 10, 12, 14, 16, 18, 20 excluding the polyurethane layer may be divided into a plurality of layers.

  Each belt has an endless shape as a whole, but each individual layer is not necessarily in the form of a layer. For example, a certain polyurethane may exist only in a part of the width direction of the belt.

  The positions of the reinforcing bases 6, 8, and 9 may be embedded in any single polyurethane layer or may extend over any plurality of polyurethane layers.

  The belt shown in FIGS. 4 to 9 includes inner polyurethane layers 10, 12, 14, 16, 18, 20 and outer polyurethane layers 11, 13, 15, 17, 19, 21.

  The inner polyurethane layers 10, 12, 14, 16, 18, and 20 are terminated with an isocyanate group (terminal) like the outer polyurethane layer (polyurethane layer constituting the outer peripheral surface) 11, 13, 15, 17, 19, and 21. NCO) is formed from a composition comprising a urethane prepolymer having NCO) and a curing agent having an active hydrogen group (H) at the terminal. A urethane prepolymer is obtained by reacting a polyol and a phenylene isocyanate derivative.

  The polyol and phenylene isocyanate derivative for obtaining the urethane prepolymer of the inner polyurethane layers 10, 12, 14, 16, 18, 20 are the outer polyurethane layers (polyurethane layers constituting the outer peripheral surface) 11, 13, 15, This is the same as described in the case of 17, 19, and 21. Curing agents for the inner polyurethane layers 10, 12, 14, 16, 18, and 20 can be selected from among curing agents such as polyols, aromatic diols, and aromatic diamines that can be generally used as curing agents for polyurethane. It can be used as one kind or a mixture of two or more kinds.

  The composition that forms the inner polyurethane layer 10, 12, 14, 16, 18, 20 has an equivalent ratio (H / NCO) of active hydrogen groups (H) of the curing agent to isocyanate groups (NCO) of the urethane prepolymer. The urethane prepolymer and the curing agent are mixed at a ratio of 0.85 ≦ H / NCO <1. In addition, the composition forming the inner polyurethane layers 10, 12, 14, 16, 18, and 20 is urethane in a ratio that the value of equivalent ratio (H / NCO) is 0.85 ≦ H / NCO ≦ 0.99. It is also possible for the prepolymer and the curing agent to be mixed.

  On the other hand, the composition forming the outer polyurethane layer 11, 13, 15, 17, 19, 21 has an equivalent ratio (H / H) of active hydrogen groups (H) of the curing agent and isocyanate groups (NCO) of the urethane prepolymer. The urethane prepolymer and the curing agent are mixed in such a ratio that the value of (NCO) is 1 <H / NCO <1.15. The equivalent ratio (H / NCO) is preferably such that the urethane prepolymer and the curing agent are mixed at a ratio of 1.01 ≦ H / NCO ≦ 1.14.

  The mixing ratio of the curing agent and the urethane prepolymer is 0.85 ≦ H / NCO <1 for the inner polyurethane layers 10, 12, 14, 16, 18, 20 and the outer polyurethane layers 11, 13, 15, 17 , 19 and 21 are set such that 1 <H / NCO <1.15, so that the inner polyurethane 10, 12, 14, 16, 18, 20 and the outer polyurethane 11, 13, 15, 17, 19, 21 Adhesive force is improved, and generation of delamination can be suppressed. The reason is that the inner polyurethane 10, 12, 14, 16, 18, 20 has a composition in which NCO groups remain stoichiometrically because 0.85 ≦ H / NCO <1, and this remains. Isocyanate group (NCO) reacts with surplus active hydrogen groups (H) of outer polyurethane 11, 13, 15, 17, 19, and 21 with 1 <H / NCO <1.15 to firmly adhere and integrate. It is thought that. The mixing ratio of the curing agent and the urethane prepolymer is 0.85 ≦ H / NCO ≦ 0.99 for the inner polyurethane layers 10, 12, 14, 16, 18, 20 and the outer polyurethane layers 11, 13 15, 17, 19, and 21 can more preferably suppress the occurrence of delamination when 1.01 ≦ H / NCO ≦ 1.14.

  The belt shown in FIG. 5 is integrated by impregnating and covering two layers of polyurethane from both sides of the base fabric 6. The adhesive surface between the inner polyurethane layer 12 and the outer polyurethane layer 13 is inside the base fabric 6. For this reason, in addition to the adhesive force, an anchor effect is obtained between the base fabric 6 and the two polyurethane layers 12 and 13, so that a strong adhesive force can be obtained and delamination of the belt can be prevented. it can.

  As a preferred embodiment of the belt shown in FIG. 5, the urethane prepolymer of the inner polyurethane 12 contains an MDI-based urethane prepolymer obtained by reacting a polyol with diphenylmethane diisocyanate (MDI), and the outer polyurethane. 13 urethane prepolymers include a TDI urethane prepolymer obtained by reacting a polyol with tolylene diisocyanate (TDI).

  Polyurethanes using MDI-based prepolymers have a relatively fast reaction and a short curing time. For this reason, when the inner polyurethane 12 is coated on the base fabric 6 at the stage of manufacturing a belt by using an MDI-based prepolymer as a main component as the inner polyurethane 12 prepolymer, 12 can be prevented from passing to the opposite surface of the base fabric 6, and the impregnation position can be stopped inside the base fabric 6. On the other hand, polyurethane using a TDI-based prepolymer has a relatively slow reaction and a long curing time. For this reason, as a prepolymer of the outer polyurethane 13, the outer polyurethane 13 can be sufficiently permeated to a position where the inner polyurethane 12 is impregnated by using a TDI-based prepolymer as a main component. Therefore, an adhesive surface between the inner polyurethane layer 12 and the outer polyurethane layer 13 can be formed inside the base fabric 6.

  Further, the inner polyurethane 12 preferably contains 50 wt% or more of the curing agent as a polyol with respect to the MDI urethane prepolymer. By doing in this way, it becomes easy to adjust the hardening time of polyurethane, and the impregnation position to the base fabric 6 can be adjusted. The polyol-based curing agent is selected from polyether polyols and polyester polyols. Examples of the polyether polyol include polyethylene glycol (PEG), polypropylene glycol (PPG), and polytetramethylene glycol (PTMG). Examples of the polyester polyol include polycaprolactone ester, polycarbonate, polyethylene adipate, polybutylene adipate, and polyhexene adipate. These can be used alone or in admixture or polymerization of two or more kinds, and these modified products can also be used. As the curing agent for the inner polyurethane 12, 50 wt% or more of the curing agent may be a polyol, and one or two or more curing agents of an aromatic diol type or aromatic diamine type may be mixed therewith.

  A further preferred embodiment of the belt shown in FIG. 5 is shown in FIG. The belt shown in FIG. 11 uses the base fabric 23 made of a woven fabric that is multi-woven in the belt shown in FIG. In order to increase the degree of impregnation of polyurethane, the base fabric 23 preferably includes a large number of voids. The use of the multi-woven base fabric 23 not only provides excellent strength of the base fabric 23 itself, but also provides the following effects. That is, by using the base fabric 23 made of multi-woven fabric, the polyurethane can be sufficiently penetrated into the base fabric 23, and the adhesive surface between the inner polyurethane layer 24 and the outer polyurethane layer 25 can be obtained. Can be formed inside the base fabric 23. In addition, a sufficient anchor effect can be obtained between both the polyurethane layers 24 and 25 and the base fabric 23. Therefore, a strong adhesive force is obtained between the inner polyurethane layer 24 and the outer polyurethane layer 25, and delamination of the belt can be prevented. Examples of the multi-weave include a four-fold weave and a three-fold weave. The polyurethane used for the belt shown in FIG. 11 is the same as that shown in FIG. A number of drain grooves 26 are formed on the outer peripheral surface of the belt shown in FIG. 11 along the traveling direction in order to increase the dewatering efficiency.

  4 to 9 and 11, the outer polyurethane layers 11, 13, 15, 17, 19, 21, 25 are all the inner polyurethane layers 10, 12, 14, 16, 18, It adheres to the outer peripheral surfaces 20 and 24 and constitutes the outer peripheral surface of the papermaking belt. In these belts, the outer polyurethane 11, 13, 15, 17, 19, 21, 25 includes, as described above, a urethane prepolymer having an isocyanate group at the terminal and a curing agent mainly composed of dimethylthiotoluenediamine. It is preferable that it is formed from the composition containing this. By using dimethylthiotoluenediamine as the main component of the curing agent of the outer polyurethane layers 11, 13, 15, 17, 19, 21, 25 including the outer peripheral surface, cracks are generated on the outer peripheral surface of the belt as described above. Can be suppressed.

  Further, as described above, the belts shown in FIGS. 4 to 9 and 11 each have a composition for forming the outer polyurethane layers 11, 13, 15, 17, 19, 21, 25 including the outer peripheral surface. The urethane prepolymer and the curing agent at a ratio such that the equivalent ratio (H / NCO) of the active hydrogen group (H) of the curing agent to the isocyanate group (NCO) of the urethane prepolymer is 1 <H / NCO <1.15. It is assumed that the agent is mixed. For this reason, even if a small crack occurs in the polyurethane 11, 13, 15, 17, 19, 21, 25 constituting the outer peripheral surface of the belt, it is possible to prevent the generated crack from developing into a large crack. In addition, it is assumed that small cracks are generated by assuming that the urethane prepolymer and the curing agent are mixed at a ratio of equivalent ratio (H / NCO) of 1.01 ≦ H / NCO ≦ 1.14. However, it is possible to prevent the generated crack from developing into a large crack more accurately.

  Furthermore, another embodiment is shown in FIG. The belt shown in FIG. 12 is impregnated and coated with an inner polyurethane layer 27 and an outer polyurethane layer 28 from both sides of a base fabric made of a multi-woven fabric, and on the outer side of the outer polyurethane layer 28, A polyurethane layer 29 constituting the surface is integrally covered. The adhesive surface between the inner polyurethane layer 27 and the outer polyurethane layer 28 is inside the base fabric 23. One or more polyurethane layers may be formed between the outer polyurethane layer 28 and the polyurethane layer 29 constituting the outer peripheral surface. In the example of FIG. 12, the position of the interface between the outer polyurethane layer 28 and the polyurethane layer 29 constituting the outer peripheral surface coincides with the surface of the base fabric 23. However, the position of the interface between the outer polyurethane layer 28 and the polyurethane layer 29 constituting the outer peripheral surface is not limited to this, and may be shifted vertically from the surface of the base fabric 23. A large number of drain grooves 26 are also formed on the outer peripheral surface of the belt shown in FIG. 12 along the traveling direction in order to increase the dewatering efficiency.

  In the belt shown in FIG. 12, the polyurethane layer 29 constituting the outer peripheral surface is formed from a composition containing a urethane prepolymer having an isocyanate group at the terminal and a curing agent mainly composed of dimethylthiotoluenediamine. . Also in this example, by using dimethylthiotoluenediamine as the main component of the curing agent of the polyurethane layer 29 constituting the outer peripheral surface, it is possible to suppress the occurrence of cracks on the outer peripheral surface of the belt as described above.

  In the belt shown in FIG. 12, the polyurethane 29 constituting the outer peripheral surface has an equivalent ratio (H / NCO) of an active hydrogen group (H) of the curing agent and an isocyanate group (NCO) of the urethane prepolymer of 1 < It is preferable that the urethane prepolymer and the curing agent are mixed at a ratio of H / NCO <1.15. By setting it as such a structure, even if a small crack generate | occur | produces in the polyurethane 29 which comprises the outer peripheral surface of a belt, it can suppress that the generated crack progresses to a large crack. In addition, it is more preferable that the urethane prepolymer and the curing agent are mixed in such a ratio that the value of the equivalent ratio (H / NCO) is 1.01 ≦ H / NCO ≦ 1.14.

  The belt shown in FIG. 12 has an outer polyurethane layer 28 between the inner polyurethane layer 27 and the polyurethane layer 29 constituting the outer peripheral surface, and therefore does not contain bubbles that cause damage or delamination. can do.

  When manufacturing a belt, first, the front and back of the base fabric 23 are reversed. Then, the inner polyurethane layer 27 is coated from the surface which becomes the back surface of the base fabric 23, and the polyurethane penetrates partway through the base fabric 23. Next, the base fabric 23 is inverted, and the outer polyurethane layer 28 is coated so as to fill the remaining portion of the base fabric 23 from the surface. Further, a polyurethane layer 29 constituting the outer peripheral surface is coated from above. In this way, the air remaining inside the base fabric 23 when the outer polyurethane 28 is coated can be expelled. Therefore, a belt that does not contain bubbles inside can be obtained.

  In the case of the belt shown in FIG. 12, the outer polyurethane 28 may be formed of the same composition as the inner polyurethane 27 or the polyurethane 29 constituting the outer peripheral surface, or may be formed of a different composition.

  In the example of FIG. 12, the polyurethane has three layers of an inner polyurethane layer 27, an outer polyurethane layer 28, and a polyurethane layer 29 constituting the outer peripheral surface, but the number of polyurethane layers is only one layer, two layers, or four layers. It may be more than a layer. For example, if the outer polyurethane layer 28 is divided into a plurality of thin layers and coated, the air inside the base fabric 23 can be expelled more effectively. Further, the inner polyurethane layer 27 can be coated in a plurality of times.

  Throughout the present invention, the polyurethane is preferably cured at a temperature of 120 ° C to 140 ° C. By doing in this way, both the crack resistance of a belt and crack progress property improve.

  Next, a method for manufacturing the belt shown in FIG. 11 will be described. As the first step, the front and back sides of the base fabric 23 made of endless woven fabric that is woven in multiple layers are inverted. Then, the inner polyurethane layer 24 is coated from the surface to be the back surface of the base fabric, and the polyurethane is infiltrated to the middle of the base fabric 23. This polyurethane contains a urethane prepolymer having an isocyanate group at the terminal and a curing agent having an active hydrogen group at the terminal, and the equivalent of the active hydrogen group (H) of the curing agent and the isocyanate group (NCO) of the urethane prepolymer. This is a mixed liquid in which a urethane prepolymer and a curing agent are mixed at a ratio such that the ratio (H / NCO) is 0.85 ≦ H / NCO <1. In addition, it is suitable to make it the liquid mixture which mixed the urethane prepolymer and the hardening | curing agent in the ratio from which the value of an equivalent ratio (H / NCO) is set to 0.85 <= H / NCO <= 0.99. The coated polyurethane is cured at a temperature of 70 ° C to 100 ° C.

  Next, as a second step, the base fabric 23 is reversed, and the outer polyurethane layer 25 is coated so as to fill the remaining portion of the base fabric 23 from the surface side. This polyurethane contains a urethane prepolymer having an isocyanate group at the terminal and a curing agent having an active hydrogen group at the terminal, and the equivalent of the active hydrogen group (H) of the curing agent and the isocyanate group (NCO) of the urethane prepolymer. This is a mixed liquid in which the urethane prepolymer and the curing agent are mixed at a ratio (H / NCO) such that the value of 1 <H / NCO <1.15. In addition, it is suitable to set it as the liquid mixture which mixed the urethane prepolymer and the hardening | curing agent in the ratio used as 1.01 <= H / NCO <= 1.14 of the equivalent ratio (H / NCO).

  Next, as a third step, the whole is heated to a temperature of 120 ° C. to 140 ° C., the mixed liquid applied on the outer peripheral surface of the inner polyurethane layer 24 is cured to form the outer polyurethane layer 25 and the inner side The polyurethane layer 24 and the outer polyurethane layer 25 are bonded and integrated.

  Then, the belt shown in FIG. 11 can be obtained by forming a large number of drain grooves 26 along the running direction on the outer peripheral surface of the belt.

  According to this method, in the first step, a polyurethane having a stoichiometric amount of NCO groups of 0.85 ≦ H / NCO <1 is brought into a semi-cured state at a relatively low temperature of 70 ° C. to 100 ° C. To do. Then, in the second step, the outer polyurethane 25 having a composition containing a large amount of curing agent 1 <H / NCO <1.15 is coated on the inner polyurethane 24 in a semi-cured state. Then, in the third step, the whole is cured by heating to a relatively high temperature of 120 ° C. to 140 ° C. For this reason, the adhesive force between the inner polyurethane layer 24 and the outer polyurethane layer 25 is improved, and the occurrence of delamination can be suppressed.

  Furthermore, since the reinforcing base material is a base fabric 23 made of a woven fabric in which multiple woven fabrics are used, it is easy to position the adhesive surface between the inner polyurethane layer 24 and the outer polyurethane layer 25 inside the base fabric 23. Become. Since the adhesive surface is inside the base fabric 23, an anchor effect is obtained between the base fabric 23 and both the polyurethane layers 24 and 25 in addition to the adhesive force. Therefore, a strong adhesive force can be obtained and delamination of the belt can be prevented.

  As a modification of the above manufacturing method, the reinforcing base material is replaced with a base fabric 23 woven multiple times, and a rough base fabric through which liquid polyurethane can sufficiently pass, or yarns 8 and 9 as shown in FIG. Can be produced as follows. The manufacturing method will be described taking the belt shown in FIG. 8 as an example. As a first step, a urethane prepolymer having an isocyanate group at the terminal and a curing agent having an active hydrogen group at the terminal are formed on the mandrel, and cured. Urethane prepolymer and curing agent at a ratio such that the equivalent ratio (H / NCO) of active hydrogen groups (H) of the agent to isocyanate groups (NCO) of the urethane prepolymer is 0.85 ≦ H / NCO <1 The mixed liquid is mixed and cured at a temperature of 70 ° C. to 100 ° C. to form the inner polyurethane layer 18. In addition, it is more suitable if a urethane prepolymer and a hardening | curing agent are mixed in the ratio from which the value of an equivalent ratio (H / NCO) will be 0.85 <= H / NCO <= 0.99. Next, the CMD-direction yarn 9 and the MD-direction yarn 8 are wound around the outer peripheral surface of the inner polyurethane as a reinforcing base material. As a second step, from the top of the reinforcing bases 8 and 9, a urethane prepolymer having an isocyanate group at the terminal and a curing agent having an active hydrogen group at the terminal, the active hydrogen group (H) of the curing agent and urethane The mixed liquid in which the urethane prepolymer and the curing agent are mixed at a ratio such that the equivalent ratio (H / NCO) of the prepolymer to the isocyanate group (NCO) is 1 <H / NCO <1.15 is coated. In addition, it is more preferable to use a mixed liquid in which a urethane prepolymer and a curing agent are mixed at a ratio of equivalent ratio (H / NCO) of 1.01 ≦ H / NCO ≦ 1.14. Next, as a third step, the whole is heated to a temperature of 120 ° C. to 140 ° C., the mixed liquid applied on the outer peripheral surface of the inner polyurethane layer 18 is cured to form the outer polyurethane layer 19 and the inner side The polyurethane layer 18 and the outer polyurethane layer 19 are bonded and integrated.

  When the belt shown in FIG. 12 is manufactured, an outer peripheral surface is further formed on the outer polyurethane layer 28 between the second step and the third step in the manufacturing method of the belt shown in FIG. A process for coating the polyurethane layer 29 may be added.

  The shoe press belt has been described above as an example, but the present invention can also be applied to a calender belt and a seat transfer belt. In the case of a calender belt and a seat transfer belt, generally no drainage groove is formed on the surface.

  As an example, the papermaking belt shown in FIG. 12 was manufactured by the following procedure. As a reinforcing base material, an endless base fabric 23 made of a newly woven fabric of a four-fold weave is prepared. This base fabric has a thickness of 2.3 mm and has a gap inside. As shown in FIG. 13, the warp yarn in the MD direction has a polyester monofilament 30 having a diameter of 0.35 mm, a polyester multifilament 31 having a diameter of 3000d, a polyester monofilament 32 having a diameter of 0.35 mm, and a diameter 0, as shown in FIG. It consists of four layers of .35 mm nylon monofilament 33, and the weft yarn in the CMD direction consists of polyester monofilament 34 with a diameter of 0.40 mm. The number of warp yarns is 68 / inch and the number of weft yarns is 56 / inch.

  As a material for the inner polyurethane layer 27, 100 parts by weight of urethane prepolymer (PTMG MDI prepolymer: NCO% = 5%) and a curing agent (PTMG and ETHACURE 300 are blended in a ratio of 65/35: equivalent value = 250) 27.4 parts by weight were individually degassed and then mixed (H / NCO = 0.92). NCO% is the weight content of isocyanate groups contained in the urethane prepolymer. This was coated on the surface of the base fabric 23 that had been turned upside down, and heated at 80 ° C. for 10 hours. The inner polyurethane layer 27 was impregnated to 50% of the thickness of the base fabric 23.

  Next, the polyurethane 27 coated on the base fabric 23 was cut and polished so that the thickness from the surface of the base fabric 23 was 1.0 mm. Then, the front and back of the base fabric 23 were reversed so that the coated surface might become inside.

  Next, 100 parts by weight of urethane prepolymer (PTMG-based TDI prepolymer: NCO% = 5%) and 13.8 parts by weight of a curing agent (ETHACURE 300: equivalent value = 107) are used as materials for forming the outer polyurethane layer 28. After defoaming individually, they were mixed (H / NCO = 1.08) and coated while being impregnated from the other surface of the base fabric 23 to the impregnation surface of the inner polyurethane layer 27. The coated surface was smoothed using a doctor blade so as to substantially coincide with the position of the surface of the base fabric 23.

  Further, as the polyurethane layer 29 constituting the outer peripheral surface, the same material as that of the outer polyurethane layer 28 was coated on the outer polyurethane layer 28. Thereafter, heating was performed for 16 hours under a temperature condition of 120 ° C. so that the inner polyurethane layer 27, the outer polyurethane layer 28, the polyurethane layer 29 constituting the outer peripheral surface, and the base fabric 23 were bonded and integrated.

  Further, the surface of the belt was cut and polished so that the polyurethane layer 29 constituting the outer peripheral surface had a thickness of 1.5 mm. Furthermore, a number of drain grooves 26 were formed on the outer surface of the belt with a groove width of 0.8 mm, a depth of 0.8 mm, and a pitch of 2.54 mm along the running direction. The obtained belt had an overall thickness of 4.8 mm and a surface hardness of 90 ° (JIS A).

  Next, samples 1 to 6 having the structure shown in FIG. 14 were prepared as shown below. That is, as the reinforcing base material, a base fabric 23 made of the same woven fabric of a four-fold weave as that used for the base fabric is prepared. As polyurethane layer 35 constituting the inner surface, 100 parts by weight of urethane prepolymer (PTMG-based MDI prepolymer: NCO% = 5%) and a curing agent (PTMG and ETHACURE 300 are blended in a ratio of 65/35: equivalent value = 250. 27.4 parts by weight were individually degassed and then mixed (H / NCO = 0.92). This was coated on the back side of the base fabric 23 and heated for 10 hours under a temperature condition of 80 ° C. The polyurethane 35 constituting the inner surface was impregnated to 50% of the thickness of the base fabric 23. Next, the polyurethane 35 coated on the base fabric 23 was cut and polished so that the thickness from the surface of the base fabric 23 was 1.0 mm.

  Next, as a material for forming the polyurethane layer 36 constituting the outer surface, the urethane prepolymers are Hyprene L-100 and L-167 (both PTMG TDI prepolymers: Mitsui Chemicals), and the curing agent is , ETHACURE 300 and MOCA were used. Using these materials, the urethane prepolymer and the curing agent are individually defoamed in each formulation shown in Table 1 and then mixed, and this is the polyurethane layer 35 constituting the inner surface from the outer surface of the base fabric 23. Coating was performed while impregnating up to the impregnated surface.

  Thereafter, heating was performed for 16 hours under a temperature condition of 120 ° C., and the polyurethane layer 35 constituting the inner surface, the polyurethane layer 36 constituting the outer surface, and the base fabric 23 were bonded and integrated. Furthermore, the surface of the belt was cut and polished so that the thickness of the polyurethane layer 36 constituting the outer surface from the surface of the base fabric 23 was 1.5 mm, and Samples 1 to 6 were obtained.

  For each sample 1-6, a test piece having a width of 20 mm and a length of 420 mm is taken. As shown in FIG. 15, while holding both ends in the length direction of the test piece 37 with the holding member 38, a metal round bar 39 having a smooth surface with a diameter of 25 mm is applied to the inside of the intermediate portion to apply a tension T. The tension T was 9.8 kN / m. While maintaining the tension T, the test piece 37 is repeatedly reciprocated at a width of 10 cm while supplying lubricating oil from the nozzle 40 between the inner surface of the test piece 37 and the round bar 39. In this way, sliding was repeated between the inner surface and the round bar 39 while applying a tension T to the test piece 37. The number of reciprocations until cracks occurred on the surface of the test piece 37 was measured and used as the durability number. The results are shown in Table 1. Moreover, the hardness about each sample 1-6 is also shown in Table 1. In addition, the compounding quantity of the hardening | curing agent in a table | surface is the weight part number of the hardening | curing agent with respect to 100 weight part of prepolymers.

  Next, samples 7 to 30 were prepared as shown below. The reinforcing base material 23 and the polyurethane layer 35 constituting the inner surface are the same as those of the samples 1 to 6 described above. As a material for forming the polyurethane layer 36 constituting the outer surface, L-100 and L-167 were used as the urethane prepolymer, and ETHACURE 300 was used as the curing agent. Using these materials, the urethane prepolymer and the curing agent were individually defoamed and mixed in each formulation with different H / NCO equivalent ratios as shown in Table 2, and this was mixed outside. Coating was performed while impregnating from the surface to the impregnated surface of the polyurethane layer 35 constituting the inner surface.

  Thereafter, heating was performed for 16 hours under a temperature condition of 120 ° C., and the polyurethane layer 35 constituting the inner surface, the polyurethane layer 36 constituting the outer surface, and the base fabric 23 were bonded and integrated. Furthermore, the surface of the belt was cut and polished so that the thickness of the polyurethane layer 36 constituting the outer surface from the surface of the base fabric 23 was 1.5 mm, and Samples 7 to 30 were obtained.

  Each sample 7-30 was subjected to a crack progress test under the following conditions using a dematcher type bending tester defined in JIS K6260. The size of the test piece was 20 mm wide and 150 mm long. The reciprocating motion was a maximum distance of 80.5 mm, a minimum distance of 38.5 mm, and a motion distance of 42.0 mm. The cut was made at the center in the length direction of the test piece and at the outer surface of one end in the width direction with a length of 3 mm and a depth of 1.5 mm. Under this condition, after bending 1000 times, the size of the crack was measured. The results are shown in the item of crack growth length in Table 2. Furthermore, about each 7-30 samples, after making it reciprocate 1 million times using the test apparatus shown in FIG. 15, it was confirmed by the visual observation whether the test piece was cracked. The result is shown in the item of presence / absence of cracks in Table 2. In addition, the compounding quantity of the hardening | curing agent in a table | surface is the weight part number of the hardening | curing agent with respect to 100 weight part of prepolymers.

  As can be seen from Table 2, in the sample in which the (H / NCO) equivalent ratio of the polyurethane constituting the outer surface is larger than 1, the crack growth length can be suppressed to be smaller than 1 mm. The larger the (H / NCO) equivalent ratio, the smaller the crack growth length. However, when the (H / NCO) equivalent ratio was increased to 1.15, generation of cracks was observed in the 1,000,000 round-trip test.

  Next, samples (31 to 36) having the structure shown in FIG. 14 were prepared as shown below by changing the (H / NCO) equivalent ratio of the polyurethane constituting the inner surface. The same reinforcing substrate 23 as that of Samples 1 to 30 was used. The polyurethane layer 36 constituting the outer surface was L-167 as a urethane prepolymer and ETHACURE 300 as a curing agent, and had the same blending ratio as the sample 27. The polyurethane layer 35 constituting the inner surface is made of the same material as used in the sample 27, that is, urethane prepolymer (PTMG-based MDI prepolymer: NCO% = 5%) and a curing agent (PTMG and ETHACURE 300). 35: blend: equivalent value = 250). However, the polyurethane layer 35 which comprises an inner surface changed into the sample 31-36 by changing the mixture ratio of a urethane prepolymer and a hardening | curing agent. Other manufacturing conditions and the thickness of each layer were the same as those of Samples 1 to 30.

  About the samples 31-36, the test piece of width 20mm and length 420mm was taken, and the durability test was done using the test apparatus shown in FIG. 15 similarly to having done with respect to the samples 1-6. In addition, evaluation was performed by confirming the state after reciprocating 2.5 million times for each sample. The results are shown in Table 3. In Table 3, the numerical values of the prepolymer and the curing agent indicate the number of parts by weight.

  When the H / NCO of the polyurethane constituting the inner surface was smaller than 0.85, the strength of the polyurethane constituting the inner surface was lowered and appeared as fine cracks. When the H / NCO of the polyurethane constituting the inner surface was 1 or more, delamination occurred.

  On the other hand, the H / NCO of the polyurethane constituting the outer surface is preferably 1 <H / NCO <1.15. According to Samples 7 to 30 shown in Table 2, cracks are likely to spread when the H / NCO of the polyurethane constituting the outer surface is 1 or less, and cracks are likely to occur when it is 1.15 or more. is there.

  The embodiments and examples disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is explanatory drawing which shows a shoe press apparatus. It is a fragmentary sectional view which shows an example of the papermaking belt by this invention. It is a fragmentary sectional view which shows the other example of the papermaking belt by this invention. It is a fragmentary sectional view which shows the further another example of the papermaking belt by this invention. It is a fragmentary sectional view which shows the further another example of the papermaking belt by this invention. It is a fragmentary sectional view which shows the further another example of the papermaking belt by this invention. It is a fragmentary sectional view which shows the further another example of the papermaking belt by this invention. It is a fragmentary sectional view which shows the further another example of the papermaking belt by this invention. It is a fragmentary sectional view which shows the further another example of the papermaking belt by this invention. It is a fragmentary sectional view which shows the further another example of the papermaking belt by this invention. It is a fragmentary sectional view which shows the further another example of the papermaking belt by this invention. It is a fragmentary sectional view which shows the further another example of the papermaking belt by this invention. It is a fragmentary sectional view which shows the structure of the base fabric used for the Example of this invention. It is a fragmentary sectional view which shows the structure of the sample used for the comparative experiment of this invention. It is a figure explaining the test apparatus of crack resistance.

Explanation of symbols

  2 Belt, 6, 23 Base fabric, 7 Polyurethane, 8 MD direction thread, 9 CMD direction thread, 10, 12, 14, 16, 18, 20, 24 Polyurethane layer constituting the inner peripheral surface (inner side), 11, 13, 15, 17, 19, 21, 25 (outer) polyurethane layer constituting the outer peripheral surface, 22, 26 drainage groove, 27 inner polyurethane layer, 28 outer polyurethane layer, 29 polyurethane constituting the outer peripheral surface Layer, 35 polyurethane layer constituting the inner surface, 36 polyurethane layer constituting the outer surface.

Claims (13)

A reinforcing substrate and a thermosetting polyurethane are integrated, and the reinforcing substrate is embedded in the polyurethane,
The polyurethane is a papermaking belt including an inner polyurethane and an outer polyurethane bonded to the outer peripheral surface of the inner polyurethane.
The inner polyurethane and the outer polyurethane are each formed from a composition comprising a urethane prepolymer having an isocyanate group at a terminal and a curing agent having an active hydrogen group at a terminal,
The composition forming the inner polyurethane has an equivalent ratio (H / NCO) of active hydrogen groups (H) of the curing agent and isocyanate groups (NCO) of the urethane prepolymer of 0.85 ≦ H / NCO <1. The urethane prepolymer and the curing agent are mixed at a ratio of
The composition forming the outer polyurethane is a mixture of a urethane prepolymer and a curing agent at a ratio such that the value of the equivalent ratio (H / NCO) is 1 <H / NCO <1.15.
Papermaking belt. The adhesive surface between the inner polyurethane and the outer polyurethane is inside the reinforcing substrate,
The urethane prepolymer of the inner polyurethane contains a urethane prepolymer obtained by reacting a polyol with diphenylmethane diisocyanate (MDI),
The outer polyurethane urethane prepolymer contains a urethane prepolymer obtained by reacting a polyol with tolylene diisocyanate (TDI).
The papermaking belt according to claim 1 . The papermaking belt according to claim 2 , wherein the inner polyurethane is a polyol in which 50 wt% or more of the curing agent is a polyol . The papermaking belt according to claim 2 or 3, wherein the reinforcing base material includes a woven fabric that is woven in multiple layers . The outer polyurethane adheres to the outer peripheral surface of the inner polyurethane and constitutes the outer peripheral surface of the papermaking belt,
And it is formed from a composition comprising a urethane prepolymer having an isocyanate group at the terminal, and a curing agent containing dimethylthiotoluenediamine.
The papermaking belt according to any one of claims 1 to 4 . The polyurethane includes an inner polyurethane, an outer polyurethane bonded to the outer peripheral surface of the inner polyurethane, and a polyurethane that is positioned further outside the outer polyurethane and constitutes the outer peripheral surface of the papermaking belt,
The polyurethane constituting the outer peripheral surface is formed from a composition including a urethane prepolymer having an isocyanate group at a terminal and a curing agent containing dimethylthiotoluenediamine.
The papermaking belt according to any one of claims 1 to 4 . The polyurethane composition constituting the outer peripheral surface has an equivalent ratio (H / NCO) of active hydrogen groups (H) of the curing agent and isocyanate groups (NCO) of the urethane prepolymer of 1 <H / NCO. The papermaking belt according to claim 6, wherein the urethane prepolymer and the curing agent are mixed at a ratio of <1.15 . The papermaking belt according to any one of claims 1 to 7, wherein the polyurethane is cured at a temperature of 120C to 140C . The papermaking belt according to any one of the drainage grooves on the outer peripheral surface that is formed according to claim 1 to claim 8. By embedding the reinforcing base material in the thermosetting polyurethane, the reinforcing base material and the thermosetting polyurethane are integrated,
In a method for producing a papermaking belt comprising an inner polyurethane and an outer polyurethane bonded to the outer peripheral surface of the inner polyurethane,
The inner polyurethane includes a urethane prepolymer having an isocyanate group at the terminal and a curing agent having an active hydrogen group at the terminal, and an active hydrogen group (H) of the curing agent and an isocyanate group (NCO) of the urethane prepolymer, The liquid mixture in which the urethane prepolymer and the curing agent are mixed at a ratio such that the value of the equivalent ratio (H / NCO) of 0.85 ≦ H / NCO <1 is cured at a temperature of 70 ° C. to 100 ° C., A first step of molding;
A urethane prepolymer having an isocyanate group at the terminal and a curing agent having an active hydrogen group at the terminal, and an equivalent ratio of the active hydrogen group (H) of the curing agent to the isocyanate group (NCO) of the urethane prepolymer (H / A second step in which a mixed liquid in which a urethane prepolymer and a curing agent are mixed at a ratio of 1 <H / NCO <1.15 is applied on the outer peripheral surface of the inner polyurethane;
The whole is heated to a temperature of 120 ° C. to 140 ° C., the mixed liquid applied on the outer peripheral surface of the inner polyurethane is cured to form the outer polyurethane, and the inner polyurethane and the outer polyurethane are bonded and integrated. Including the third step,
A method for manufacturing a papermaking belt. The inner polyurethane impregnates the reinforcing base material from one side of the reinforcing base material to the middle of the thickness of the reinforcing base material,
The outer polyurethane impregnates the reinforcing base material from the other side of the reinforcing base material to a position where the inner polyurethane is impregnated with the reinforcing base material.
The method for producing a papermaking belt according to claim 10 . The method for manufacturing a papermaking belt according to claim 11, wherein the reinforcing base material includes a multi-woven fabric . The method for manufacturing a papermaking belt according to claim 10, comprising a step of winding the reinforcing base material on an outer peripheral surface of the inner polyurethane before or after the inner polyurethane is cured .

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