EP1899528A2

EP1899528A2 - Smoothing press apparatus

Info

Publication number: EP1899528A2
Application number: EP06747211A
Authority: EP
Inventors: Yasuhiko Kobayashi; Hiroyuki Takamura; Akira Onikubo
Original assignee: Ichikawa Co Ltd
Current assignee: Ichikawa Co Ltd
Priority date: 2005-05-31
Filing date: 2006-05-31
Publication date: 2008-03-19
Also published as: KR20080014982A; CA2605945A1; JP2007009389A; WO2006129871A2; WO2006129871A3; US20090014143A1

Abstract

In order to provide a smoothing press apparatus suitable to be applied to a closed draw type paper machine for allowing the surface of the wet paper to be smoothed and papermaking to be performed in a high speed, the smoothing press apparatus 100 is mounted on a last stage of the press part 11 of the closed draw type paper machine, and includes a smoothing press 17 having a pair of press rolls 23 and 25, a smoothing belt 27 interposed between the smoothing press 17 together with the wet paper W to smooth the surface of the wet paper, and a wet paper conveyer felt 21 for conveying the wet paper W and passing over it to the smoothing belt 27.

Description

DESCRIPTION

SMOOTHING PRESS APPARATUS

Technical Field

Field of the Invention

The present invention relates to a smoothing press apparatus, and more particularly, to a smoothing press apparatus suitable for a closed draw type paper machine in which the surface of the wet paper is smoothed while one side of the wet paper is retained and conveyed by a smoothing belt.

Background Art

Typically, a paper machine comprises a wire part, press part, and a drier part. The wire part, the press part, and the drier part are arranged in this order along a conveyance direction. Moisture contained in the wet paper is^'- squeezed while the wet paper is sequentially conveyed via paper conveyance tools installed in each of the wire part, the press part, and the drier part. Finally, the wet paper is dried in. the drier part. The press device provided in the press part includes a plurality of press tools arranged in series along a conveyance direction of the wet paper. Each press tool includes a pair of wet paper conveyer felts having an endless belt shape and a pair of rolls (i.e., a roll press) or a roll and shoe (i.e., a shoe press) facing each other on and beneath a pair of the wet paper conveyer felts, so that a part of each wet paper conveyer felt is interposed between the pair of rollers or the roller and the shoe.' Moisture contained in the wet paper is squeezed and absorbed by the wet paper conveyer felts while the wet paper, which is conveyed by the wet paper conveyer felts driven in nearly the same direction and speed, is pressed by the pair of rolls or the roll and shoe together with the wet paper conveyer felt. In addition, there is another type of paper machine including a smoothing press device disposed at an end of the press device provided in the press part in order to smooth the surface of the wet paper by pressing the wet paper conveyed by a smoothing belt together with a smoothing belt. As this type of paper machine, there are a roll press type paper machine, in which the press part includes^'- a press device for pressing the wet paper while a part of the wet paper conveyer felts retaining the wet paper is interposed between a pair of rolls, and. a shoe press type paper machine, in which the press part includes a press device for pressing the wet paper while a part of the wet paper conveyer felts retaining the wet paper is interposed between a roll and a shoe, and the like. In addition, the paper machines are classified into a closed draw type paper machine, in which the wet paper is conveyed while one or both surfaces of the wet paper is always retained by a conveyer felt or belt, and an open draw type paper machine having an interval, in which the wet paper is not retained by the conveyer felt but conveyed by itself. The closed draw type paper machine can make paper in a high speed manner because the wet paper is conveyed while it is retained in the conveyer felt or belt. However, there is a concern that the smoothness of a surface making contact with the conveyer felt or belt is reduced because at least a single surface of the wet paper makes contact with the conveyer felt or belt. Particularly, recently, a shoe press having a high water-squeezing property and high papermaking efficiency has been used in the closed draw type paper machine. Improvement of the smoothness of the wet paper surface was difficult in this type of paper machine .

In order to improve the smoothness of both surfaces of the wet paper and to make a large volume of paper, a smoothing press could be disposed in the end stage of the press part to improve surface smoothness of the wet paper that has been water-squeezed. However, most of the conventional smoothing presses are installed in the open draw type paper machine. Thus, it is difficult to improve the surface smoothness of the wet paper while the papermaking is performed in a high speed.

As a conventional paper machine in which a smoothing press is installed in the closed draw type paper machine, the wet paper is conveyed while one side of the wet paper is retained by an elastic member, and the wet paper is pressed by a pair of press rolls together with the elastic member so that the surface of the wet paper is smoothed (For example, refer to the patent document 1) .

In addition, there is a paper machine in which a liquid blocking layer is formed on the surface of the wet paper conveyer felt (refer to the patent document 2) . This type of wet paper conveyer felt comprises a fiber layer having thermoplastic fibers or meltable fibers, and the thermoplastic fibers or meltable fibers are melted by heating the surface of the fiber layer, so that the liquid blocking layer is formed.

(Patent Document 1) International Laid-open Pamphlet WO2004/101885

(Patent Document 2) German Unexamined Utility Model Application Publication No. DE29706427U1. Disclosure of the Invention

Problems to be Solved by the Invention

The smoothing press of the paper machine disclosed in the patent document 1 adopts a paper-passing belt having no porosity or a surface improving felt having porosity as an elastic member pressed by a pair of press rolls together with the wet paper while one side of the wet paper is retained. A rubber belt is exemplified as the paper-passing belt having no porosity, and a felt having some porosity not greater than 10 cc/ (Sec- cm²) is exemplified as the surface improving felt. However, recently, demands for papermaking at a higher speed and improved surface smoothing of the wet paper have increased. The conventional paper machine is not sufficient to satisfy such demands, and there is necessity for improvement.

In the wet paper conveyer felt disclosed in the patent document 2, the liquid blocking layer is formed by heating the surface of the fiber layer, including the thermoplastic fibers or meltable fibers, to melt the thermoplastic fibers or the meltable fibers. This wet paper conveyer felt is characterized in that the thickness of the liquid blocking layer can be somewhat controlled by adjusting the heat amount applied from the surface of the fiber layer. However, the wet paper conveyer felt disclosed in the patent document 2 lacks softness because the thermoplastic fibers or the meltable fibers included in a base of the wet paper conveyer felt are hardened. Therefore, it is difficult to make paper having a great volume or to guarantee durability of the wet paper conveyer felt. In addition, since the surface directly making contact with the wet paper is made of a fiber layer that does not include the thermoplastic fibers or meltable fibers, a significantly high pressure or friction is received when the pressing is applied from the pressing portion so that fibers of the surface of the fiber layer may fall out or be cut out (i.e., depilation) . The depilation of fibers on the surface of the fiber layer that directly makes contact with the wet paper of the wet paper conveyer felt degrade quality of the paper products such as a print product. On the other hand, since the surface of the fiber layer is made harsh by the depilation, the surface smoothness of the wet paper i& significantly reduced.

The present invention has been made to solve the aforementioned problems, and an object of the present invention is to provide a smoothing pressing device suitable for applying it to the closed draw type paper machine allowing the wet paper surface to be smoothed and the papermaking process to be performed in a high speed. Means for Solving the Problems

In order to achieve the aforementioned object, the smoothing press apparatus according to the present invention has the following characteristics (1) , (2) , (3), (4), (5), (6), (7), (8), (9), and (10) :

(1) There is provided a smoothing press apparatus mounted in a press device provided in a press part of a closed draw type paper machine, the smoothing press apparatus comprising: a first press roll having a smooth surface; a second press roll having a smooth surface and facing the first press roll; a smoothing belt interposed between the first and second press rolls together with the wet paper to smooth a surface of the wet paper; and a wet paper conveyer felt for conveying the wet paper and passing over it to the smoothing belt, wherein the wet paper conveyer felt has a wet paper contact fiber layer that includes at least a splittab^'le fiber and directly makes contact with the wet paper, and wherein the smoothing belt includes a base body and a polyurethane layer that directly makes contact with the wet paper.

(2) In the smoothing press apparatus of (1), polyurethane included in the polyurethane layer of the smoothing belt contains a non-reactive polydimethylsiloxane liquid and has a hardness degree of 90° to 98° in a JIS A hardness standard.

(3) In the smoothing press apparatus of (1), polyurethane included in the polyurethane layer of the smoothing belt is a mixture of polyurethane having a hardness degree of 90° to 95° in a JIS A hardness standard and containing a non-reactive polydimethylsiloxane liquid and polyurethane having a hardness degree of 95° to 98° in a JIS A hardness standard and not containing a non-reactive polydimethylsiloxane liquid.

(4) In the smoothing press apparatus of (1) , polyurethane included in the polyurethane layer of the smoothing belt is formed by curing a mixture of urethane polymer, a curing agent, and a non-reactive polydimethylsiloxane liquid having a weight percentage of 0.5 to 25 wt % with respect to a summed amount of the urethane polymer and the curing agent.

(5^') In the smoothing press apparatus of (4), the curing agent is dimethylthiotoluenediamine or methylene- bisorthochloroaniline .

(6) In the smoothing press apparatus of any one of (I)- (5), the wet paper conveyer felt comprises: a base body; a first batt layer formed on a surface of the wet paper side of the base body; a second batt layer formed on a surface of the roll side of the base body; and a wet paper contact fiber layer including a splittable fiber and formed on a surface of the wet paper side of the first batt layer to. directly make contact with the wet paper.

(7) In the smoothing press apparatus of any one of (I)- (5), the wet paper conveyer felt comprises: a base body; a first batt layer formed on a surface of the wet paper side of the base body; a second batt layer formed on a surface of the roll side of the base body; a wet paper contact fiber layer including a plurality of splittable fibers split into filaments and a polymer elastic material impregnated into intervals of the filaments, the wet paper contact fiber layer being formed on a surface of the wet paper side of the first batt layer so that the filaments and the polymer elastic material directly make contact with the wet paper; and a hydrophilic non-woven layer disposed between the first batt layer and the wet paper contact fiber layer.

(8^') In the smoothing press apparatus of (7), the polymer elastic material contained in the wet paper contact fiber layer has a weight percentage of 1 to 10 wt %.

(9) In the smoothing press apparatus of any one of (6) -(8), the fiber contained in the wet paper contact fiber layer is composed of a splittable fiber having a weight percentage of 15 to 100 wt % and a non-splittable fiber occupying the remaining portion.

(10) In the smoothing press apparatus of any one of (6) -(9), the splittable fiber has a fiber fineness of 3.3 dtex or less before splitting.

According to the smoothing press apparatus of (1), the wet paper is conveyed by the non-permeable wet paper conveyer felt having the wet paper contact fiber layer that includes the splittable fiber and directly makes contact with the wet paper, passes over to the non- permeable smoothing belt having the base body and the polyurethane layer and is interposed between a pair of press rolls together with the smoothing belt, so that the surface of the wet paper can be smoothed. The wet paper has a characteristic that the conveyed wet paper is attached to a surface having higher hardness and higher smoothness when the nip pressure is applied to the wet paper W while it is interposed between the wet paper conveyer felt and the smoothing belt. Therefore, the wet paper conveyed by the wet paper conveyer felt is surely passed over to a smoothing belt having a surface of high hardness and high smoothness. In addition, the wet paper is pressed by a pair of press rolls together with the smoothing belt. Thus, the surface making contact with the smooth surface of the smoothing belt can be smoothed. According to the smoothing press apparatus of any one of (2) -(5), since the polyurethane contained in the smoothing belt is made of a material including a particular element, it is possible to provide excellent crack resistance, wear resistance, bending fatigue resistance, permanent distortion resistance, and the like. Therefore, the smoothing belt can be used in coarse environments such as a high speed papermaking and a high pressure press part for a long time.-- Particularly, the wear resistance of the surface of the smoothing belt is significantly improved, and few cracks are generated. The wet paper, which makes contact with the smoothing belt having such a smooth surface and is pressed, can have a smoothed surface.

According to the smoothing press apparatus of any one of (6) -(10), the wet paper conveyer felt includes the base body, the first batt layer formed on the wet paper side surface of the base body, the second batt layer formed on the roll side surface of the base body, and the wet paper contact fiber layer formed on the surface of the wet paper of the first batt layer and including at least the splittable fiber. The wet paper contact fiber layer includes a splittable fiber that can be split into very fine filaments. Therefore, it is possible to improve the surface smoothness of the wet paper. In. addition, such a wet paper conveyer felt can be suitably used in combination with the smoothing belt including the base body and the polyurethane layer and having a surface smoother than that of the wet paper contact fiber layer.

In addition, the wet paper contact fiber layer of the wet paper conveyer felt contains a plurality of splittable fibers split into filaments and a polymer elastic material impregnated into intervals of the filaments and having a weight percentage of 1 to 10 wt %, and the wet paper conveyer felt has a hydrophilic non- woven layer disposed between the first batt layer and the wet paper contact fiber layer thereon. Therefore, it is possible to obtain the wet paper conveyer felt having appropriate permeability, compressive elasticity (i.e. cushion) , and excellent paper separability even when the surface is smooth. As a result, it is possible to surely convey the wet paper. Particularly, since the hydrophilic non-woven layer, disposed between the first batt layer and the wet paper contact fiber layer in the wet paper conveyer felt, has a rewetting preventing function for the wet paper, the wet paper is not rewetted when the wet paper is passed over to the smoothing belt. Furthermore, in order to obtain the wet paper having a smoothed surface, the fiber contained in the wet paper contact fiber. layer preferably is composed of the splittable fiber having a weight percentage of 15 to 100 wt % and the non-splittable fiber having a weight percentage of the remaining portion, and the splittable fiber preferably has a fineness of 3.3 dtex or less before splitting.

In addition, the smoothing press apparatus according to the present invention has the following characteristics (11), (12), (13), (14), (15), and (16):

(11) There is provided a smoothing press apparatus mounted in a press device provided in a press part of a closed draw type paper machine, the smoothing press apparatus comprising: a first press roll having a smooth surface; a second press roll having a smooth surface and facing the first press roll; a smoothing belt interposed between the first and second press rolls together with the wet paper to smooth a surface of the wet paper; and a wet paper conveyer felt for conveying the wet paper and passing over it to the smoothing belt. The wet paper conveyer felt has a 3-dimensional woven structure including a base body, a batt layer, two stitch grounds, and interlink yarns for interlinking the two stitch grounds, part of the interlink yarns being crosslinked diagonally; and the smoothing belt includes at least a wet paper contact fiber layer that includes a splittable fiber and directly makes contact with the wet paper.

(12) In the smoothing press apparatus of (11), the smoothing belt comprises: a base body; a first batt layer formed on a surface of the wet paper side, of the base body; a second batt layer formed on a surface of the roll side of the base body; and a wet paper contact fiber layer including a splittable fiber and formed on a surface of the wet paper side of the first batt layer, the wet paper contact fiber layer directly making contact with the wet paper.

(13) In the smoothing press apparatus of (12), the smoothing belt comprises: a base body; a first batt layer formed on a surface of the wet paper side of the base body; a second batt layer formed on a surface of the roll side of the base body; and a wet paper contact fiber layer including a plurality of splittable fibers split into filaments and a polymer elastic material impregnated into intervals of the filaments. The wet paper contact fiber layer is formed on a surface of the wet paper side of the first batt layer so that the filaments and the polymer elastic material directly make contact with the wet paper; and a hydrophilic non-woven layer disposed between the first batt layer and the wet paper contact fiber layer.

(14) In the smoothing press apparatus of (13), the polymer elastic material contained in the wet paper contact fiber layer has a weight percentage of 1 ^' to 10 wt %.

(15) In the smoothing press apparatus of any one of (11) -(14), the fiber contained in the wet paper contact fiber layer is composed of a splittable fiber having a weight percentage of 15 to 100 wt % and a non- splittable fiber occupying the remaining portion.

(16) In the smoothing press apparatus of any one of (11) -(15), the splittable fiber has a fiber fineness of 3.3 dtex or less before splitting.

According to the smoothing press apparatus of (11) , the wet paper is conveyed by the permeable wet paper conveyer felt including a base, a batt layer, and a 3-dimensional woven structure having two stitch grounds and interlink yarns for interlinking the two stitch grounds, part of the interlink yarns are crosslinked diagonally; is passed over to the micro-permeable smoothing belt having the wet paper contact fiber layer that includes at least a splittable fiber and directly makes contact with the wet paper; and is interposed between a pair of press rolls together with the smoothing felt to smooth the surface of the wet paper. Therefore, the wet paper contact fiber layer includes a splittable fiber that can be split into very fine filaments. As a result, it is possible to improve the surface smoothness of the wet paper that makes contact with the wet paper contact fiber layer and thus, obtain the wet paper having high surface smoothness.

According to the smoothing press apparatus of (12) -(16), since the wet paper contact fiber layer contains a plurality of splittable fibers split into filaments and a polymer elastic material having a weight percentage of 1 to 10 wt % and impregnated into intervals of the filaments, the filaments are somewhat combined by the polymer elastic material. As a result, so called, depilation seldom occurs, and falling-out of the filaments from the smoothing belt can be prevented, so that it is possible to obtain the wet paper having a very smooth surface. In addition, since the smoothing belt has appropriate compressive elasticity, it is possible to form a large volume of the wet paper.

In addition, since the fiber contained in the wet paper contact fiber layer is composed of a splittable fiber having a weight percentage of 15 to 100 wt % and a non-splittable fiber occupying the remaining portion, it is possible to select the characteristic of the smoothing belt by appropriately changing the mixed ration between the splittable and non-splittable fibers. Furthermore, in order to obtain the wet paper having a smooth surface, the splittable fiber preferably has a fineness of 3.3 dtex or less before splitting.

Furthermore, the smoothing press apparatus according to the present invention has the following characteristics (17), (18), (19), (20), (21), (22), and (23) :

(17) There is provided a smoothing press apparatus mounted in a press device provided in a press part of a closed draw type paper machine, the smoothing press apparatus comprising: a first press roll having a smooth surface; a second press roll having a smooth surface and facing the first press roll; a smoothing belt interposed between the first and second press rolls together with the wet paper to smooth a surface of the wet paper; and a wet paper conveyer felt for conveying the wet paper and passing over it to the smoothing belt, wherein the wet paper conveyer felt has a wet paper contact fiber layer that includes at least a meltable fiber and directly makes contact with the wet paper, and wherein the smoothing belt includes a base body and a polyurethane layer that directly makes contact with the wet paper.

(18) In the smoothing press apparatus of (17), the wet paper conveyer felt comprises: a base body; a first batt layer formed on a surface of the wet paper side of the base body; a second batt layer formed on a surface of the roll side of the base body; and a wet paper contact fiber layer including a meltable fiber and formed on a surface of the wet paper side of the first batt layer. The wet paper contact fiber layer directly makes contact with the wet paper.

(19) In the smoothing press apparatus of (17), the wet paper conveyer felt comprises: a base body; a first batt layer formed on a surface of the wet paper side of the base body and including the meltable fiber; a second batt layer formed on a surface of the roll side of the base body and including the meltable fiber; and a wet paper contact fiber layer formed on a surface of the wet paper side of the first batt layer. The wet paper contact fiber layer directly makes contact with the wet paper.

(20) In the smoothing press apparatus of (17) , the wet paper conveyer felt comprises: a base body; a first batt layer formed on a surface of the wet paper side of the base body; a second batt layer formed on a surface of the roll side of the base body and including the meltable fiber; and a wet paper contact fiber layer formed on a surface of the wet paper side of the first batt layer. The wet paper contact fiber layer directly makes contact with the wet paper.

(21) In the smoothing press apparatus of (17), the wet paper conveyer felt comprises: a base body; a first batt layer formed on a surface of the wet paper side of the base body and including the meltable fiber; a second batt layer formed on a surface of the roll side of the base body and including the meltable fiber; and a wet paper contact fiber layer including the meltable fiber and formed on a surface of the wet paper side of the first batt layer. The wet paper contact fiber layer directly makes contact with the wet paper.

(22) In the smoothing press apparatus of any one of (17), (18), and (21), the wet paper conveyer felt comprises: a base body; a first batt layer formed on a surface of the wet paper side of the base body; a second batt layer formed on a surface of the roll side of the base body; and a wet paper contact fiber layer including the meltable fiber melted with a thermal work and formed

• on a surface of the wet paper side of the first batt layer so that the meltable fiber directly can make contact with the wet paper.

(23) In the smoothing press apparatus of any one of (17) -(22), the fiber for forming the first batt layer, the second batt layer, and the wet paper contact fiber layer containing the meltable fiber includes a meltable fiber having a weight percentage of 15 to 100 wt % and a non-meltable fiber occupying the remaining portion.

According to the smoothing press apparatus of (17) , the wet paper is conveyed by the micro-permeable wet paper conveyer felt having the wet paper contact fiber layer which contains a meltable fiber and directly makes contact with the wet paper, is passed over to the non-permeable smoothing belt including a base and a polyurethane layer, and is interposed between a pair of press rolls together with the smoothing belt, so that surface of the wet paper is smoothed. The meltable fibers are melted by a heat and combined with one another, so that porosity of the wet paper conveyer felt is reduced and its surface is smoothed. Therefore, by adjusting the heating method, it is possible to obtain the wet ^'paper conveyer felt having water permeability, compressive elasticity (i.e., cushion), and a smoothed surface. In addition, it is possible to smooth the surface of the wet paper while rewetting is effectively prevented. Furthermore, the wet paper can be surely passed over to the smoothing belt because excellent paper separability can be guaranteed even when the surface of the wet paper conveyer felt is smooth. According to the smoothing press apparatus of any^¬ one of (18)-(23), it is possible to provide the wet paper conveyer felt in which the meltable fiber is contained in a selected single layer or a plurality of layers of the first and second batt layers, and the wet paper contact fiber layer included in the wet paper conveyer felt. As a result, the micro-permeable layer can be formed in a selected layer. In addition, it is possible to easily obtain the wet paper conveyer felt having water permeability and surface smoothness appropriate to the characteristic of the wet paper, to be processed. Furthermore, it is possible to effectively produce wet paper having a smooth surface and excellent paper separability.

In addition, since appropriate water permeability cannot be obtained when the entire wet paper contact fiber layer is melted, the wet paper contact fiber layer includes partially melted fibers and melted meltable fibers by virtue of a heat treatment in which part of the meltable fibers and the non-meltable fibers are not melted. Therefore, it is possible to obtain the wet paper conveyer felt having appropriate permeability and surface smoothness. As a result, it is possible to surely pass over the wet paper to the smoothing belt because excellent paper separability is obtained even when the surface is smooth.

Furthermore, since the fiber for forming the first batt layer, the second batt layer, and the wet paper ^' contact fiber layer containing the meltable fiber includes the meltable fiber having a weight percentage of 15 to 100 wt % and the non-meltable fiber occupying the remaining portion, it is possible to selected the characteristic of the wet paper conveyer felt by appropriately changing the mixed ratio between the meltable and the non-meltable fibers. This wet paper conveyer felt includes the base body and the polyurethane layer, and is suitable to use in combination with the smoothing belt having a smoother surface than that of the wet paper contact fiber layer.

Effects of the Invention

According to the smoothing press apparatus of the present invention, there is provided a combination of a micro-permeable wet paper conveyer felt having a wet paper contact fiber layer that includes a splittable fiber and directly makes contact with the wet paper, and a non-permeable smoothing belt including a base body and a polyurethane layer; a combination of a permeable wet paper conveyer felt including a base body , a batt layer, and a 3-dimensional woven layer having two stitch grounds, interlink yarns for interlinking the two stitch grounds, part of the interlink yarns are crosslinked diagonally, and a micro-permeable smoothing belt having a wet paper contact fiber layer that includes at least a splittable fiber and directly makes contact with the wet paper; or a combination of a wet paper conveyer felt in which the meltable fiber is contained in a selected single layer or a plurality of layers of the first and second batt layers and the wet paper contact fiber layer, and a non-permeable smoothing belt including a base body and a polyurethane layer. In this case, the wet paper is conveyed by the wet paper conveyer felt, passed over to the smoothing belt, and pressed by a pair of press rolls together with the smoothing belt, so that the surface of the wet paper is smoothed. Therefore, the wet paper can be surely passed over from the wet paper conveyer felt to the smoothing felt, and also, the wet paper having high surface smoothness can be obtained at a high speed.

Now, the present invention will be described in brief. In addition, the details of the present invention will be more apparent by thoroughly reading the best mode for embodying the present invention, which will be described below, with reference to the accompanying drawings . Brief Descriptions of the Drawings

Fig. 1 is a schematic diagram illustrating a closed draw type paper machine having a smoothing press apparatus according to the first embodiment of the present invention.

Fig. 2 is a transverse cross-sectional view illustrating a smoothing belt.

Fig. 3 is a transverse cross-sectional view illustrating a wet paper conveyer felt.

Fig. 4 is an enlarged transverse cross-sectional view illustrating splittable fibers for forming a wet paper contact fiber layer.

Fig. 5 is a transverse cross-sectional view illustrating another wet paper conveyer felt.

Fig. 6 is a schematic structural view illustrating a closed draw type paper machine having a smoothing press apparatus according to the second embodiment of the present invention.

Figs. 7 (a) to 7 (d) are transverse cross-sectional views illustrating a wet paper conveyer felt having a 3- dimensional woven, each of which shows a variation of the embodiment for modifying arrangements of the 3- dimensional woven.

Fig. 8 is an enlarged view illustrating a 3- dimensional woven structure, of which Fig. 8 (a) is a perspective view illustrating a 3-dimensional woven; Fig. 8 (b) is a side view of Fig. 8 (a) illustrated from an arrow B; and Fig. 8 (c) is a side view of Fig. 8 (a) illustrated from an arrow C.

Fig. 9 is a side view illustrating a 3-dimensional woven structure.

Fig. 10 is a top plan view illustrating a stitch ground of the.3-dimensional woven structure.

Fig. 11 is a top plan view illustrating a stitch ground of the 3-dimensional woven structure.

Figs. 12 (a) and 12 (d) are transverse cross- sectional views illustrating a wet paper conveyer felt according to the third embodiment of the present invention, each of which shows a variation of the embodiment for modifying arrangement of a fiber layer including meltable fibers.

Fig. 13 is an enlarged cross-sectional view illustrating meltable fibers.

Fig. 14 is a schematic diagram for describing a heat treatment device of the wet paper conveyer felt including meltable fibers .

Descriptions of Reference Numerals

100: SMOOTHING PRESS APPARATUS 200: SMOOTHING PRESS APPARATUS 11: PRESS PART 17: SMOOTHING PRESS 1: WET PAPER CONVEYER FELT 3: FIRST PRESS ROLL 5: SECOND PRESS ROLL 7: SMOOTHING BELT 1: BASE BODY 33: POLYURETHANE LAYER 41: BASE BODY 43: BATT LAYER 43A: FIRST BATT LAYER 43B: SECOND BATT LAYER 45: WET PAPER CONTACT FIBER LAYER 53: SPLITTABLE FIBERS 53: HYDROPHILIC NON-WOVEN LAYER 55: POLYMER ELASTIC MATERIAL 121: WET PAPER CONVEYER FELT 127: SMOOTHING BELT 141: BASE BODY 143: BATT LAYER 151: 3-DIMENSIONAL WOVEN 153: FIRST STITCH GROUND 155: SECOND STITCH GROUND 157: CROSS-LINKING YARN 221: WET PAPER CONVEYER FELT 241: BASE BODY 243A: FIRST BATT LAYER 243B: SECOND BATT LAYER 245: WET PAPER CONTACT FIBER LAYER

249: MELTABLE FIBER

255: THERMAL PRESS ROLL (HEAT TREATMENT DEVICE)

W: WET PAPER

Best Mode for Carrying out the Invention

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings .

(First Embodiment)

Fig. 1 is a schematic structural diagram illustrating a closed draw type- paper machine having a smoothing press apparatus according to the first embodiment of the present invention, Fig. 2 is a transverse cross-sectional view illustrating a smoothing belt, Fig. 3 is a transverse cross-sectional view illustrating a wet paper conveyer felt, Fig. 4 is an enlarged' cross-sectional view illustrating splittable fibers for forming a wet paper contact fiber layer, and Fig. 5 is a transverse cross-sectional view illustrating another wet paper conveyer felt.

As shown in Fig. 1, the closed draw type paper machine includes a press part 11 and a drier part 13 arranged in this order in series along a conveyance direction of the wet paper W. The smoothing press 17 of the smoothing press apparatus 100 is arranged in a downstream side of the final water-squeezing press rolls 15A and 15B, which are a last stage of the press part 11. The water-squeezing press rolls 15A and 15B face each other and interpose a conveyance path of the wet paper W. The water-squeezing press rolls 15A and 15B are used to squeeze water in the wet paper W by pressing the wet paper conveyer felt 21 and the conveyer felt 19 together with the wet paper W while the wet paper is retained.

The smoothing press 17 smooths the surface of the wet paper that has been water-squeezed and conveys it to the drier part 13. The smoothing press 17 has first and second press rolls 23 and 25 arranged to face each other. The wet paper W is interposed between the rolls 23 and 25. The first and second press rolls 23 and 25 have a smooth surface with high surface hardness. The first and second press rolls 23 and 25 smooth both surfaces of the wet paper by pressing the smoothing belt 27 together with the wet paper W while one surface of the wet paper W is retained.

A pair of transfer rolls 29A and 29B are disposed between the water-squeezing press rolls 15A and 15B and the smoothing press 17. The wet paper W is pressed to generate a nip pressure while the wet paper W interposed between the wet paper conveyer felt 21 and the smoothing belt 27, so that the wet paper W conveyed from the wet paper conveyer felt 21 is delivered to the smoothing belt 27.

Now, the smoothing belt 27 used in the smoothing press apparatus 100 according to the present embodiment will be described in detail. As shown in Fig. 2, the smoothing belt 27 is formed by stacking a polyurethane layer 33 on both sides of a base body 31. The base body 31 may be made of a film or woven structure including, for example, polyamide, polyester, aromatic polyamide, aromatic polyimide, high strength polyethylene, and the like, or have a spiral shape in which a narrow band is wound around it. In addition, the base body 31 may be woven by weaving a yarn material 35 arranged in a machine direction MD (i.e., the driving direction of the wet paper) and a yarn material 37 arranged in a crossed machine direction CMD (i.e., a transverse direction), or the base body 31 may have an overlapped structure made by overlapping both yarn materials 35 and 37, or an spiral structure in which a film, a woven, or a narrow band is wound around it. The polyurethane for forming the polyurethane layer 33 may contain non-reactive polydimethylsiloxane liquid and have a hardness degree of 90° to 98° in a JIS A hardness standard (hereinafter/ referred to as a hardness degree) . Otherwise, the polyurethane layer 33 may be made of a mixture of first polyurethane that does not contain non-reactive polydimethylsiloxane liquid and has a hardness degree of 90° to 95° and second polyurethane that does not contain non-reactive polydimethylsiloxane liquid and has a hardness degree of 95° to 98° . In addition, the polyurethane layer 33 may be made by curing a mixture of urethane polymer, a curing agent, and non-reactive polydimethylsiloxane liquid.

In the smoothing belt 27 having such a construction, after the polyurethane layer 33 is cured, the surface of the polyurethane layer 33 is polished to provide a predetermined thickness as well as a smooth surface.^'- In addition, the smoothing belt 27 having such a construction has many advantages such as good crack resistance, good wear resistance, good bending fatigue resistance, or good permanent distortion resistance. Particularly, excellent crack resistance is important so that the smoothing belt 27 can make contact with the wet paper W to smooth the surface of the wet paper. Therefore, it is possible to use the smoothing belt 27 having such a construction for a long time even in a coarse environment such as a high speed papermaking or a high pressure press part.

Now, the wet paper conveyer felt 21 will be described. As shown in Fig. 3, the wet paper conveyer felt 21 used in the smoothing press apparatus 100 according to the present embodiment includes a base body 41, a batt layer 43 (including first and second batt layers 43A and 43B) , and a wet paper contact fiber layer 45. More specifically, the first batt layer 43A is formed on the surface of the wet paper of the base body 41, the second batt layer 43B is formed on the surface of the roll or shoe side of the base body 41, and the wet paper contact fiber layer 45 is formed on the surface of the wet paper side of the first batt layer 43A so as to directly make contact with the wet paper. The wet paper contact fiber layer 45 and the batt layer 43 are a combination of staple fibers. The batt layer 43 is formed by stacking staple fibers on the base body 41 using a carding device (not shown in the drawing) , and the wet paper contact fiber layer 45 is formed on the batt layer 43 in the same way. The base body 41, the wet paper contact fiber layer 45, and the batt layer 43 are needle-punched so that they are interlocked. As such, the base body 41, the batt layer 43 (including first and second batt layers 43A and 43B) , and the wet paper contact fiber layer 45 are interlocked through the needle-punching.

The base body 41 allows the wet paper conveyer felt 21 to have strength and may be made of a woven material including synthetic fibers such as nylon 6 or nylon 66, which provide excellent wear resistance, fatigue resistance, extendibility, and pollution prevention; natural fibers such as wool; a non-woven material having an overlapped structure instead of weaving, or a film structure; and the like. The present embodiment adopts a woven material as the base body 41.

The batt layer 43 (including the first and second batt layers 43A and 43B) is a non-splittable fiber layer formed of staple fibers 47 having a fiber fineness of 6 dtex or more (typically, about 17 dtex) . A material used to form ^'the base body 41 may be appropriately used as a material for forming the batt layer 43. In addition, the second batt layer 43B may be omitted from the wet paper conveyer felt 21.

The wet paper contact fiber layer 45 includes splittable fibers. That is, the splittable fiber 45A has a weight percentage of 100 wt % of the wet paper contact fiber layer 45. As shown in Fig. 4, the splittable fiber 45A for forming the wet paper fiber layer 45 is a composite fiber having a structure for splitting into a plurality of filaments (including a petal part 49 and a stem part 51, which will be described below) during a manufacturing process of the wet paper conveyer felt 21. Preferably, the splittable fiber 45A has a fineness of 3.3 dtex or less. In the present embodiment, the splittable fiber 45A has a fineness of 1.9 dtex, a circular cross-section, and a length of 51 mm. For example, the splittable fiber 45A consists of 7 parts, including: 6 petal parts 49 having a fan shape cross- section and an asterisk-shaped stem part 51, which is adjacent to the petal parts 49 but combines side surfaces of the petal parts 49. These parts are combined in a circular cross-section and formed in a splittable shape.

The splittable fiber 45A may be formed of, for example,^' nylon 6 (i.e., N6) , and the stem part 51 may be formed of poly (butylene terephthalate) (i.e., PBT). As a specific example of the splittable fiber 45A, there is a product name TpA31J made by Toray Industry Inc. In addition, the fineness of the splittable fiber 45A is 3.3 dtex or less in order to form easily the wet paper contact fiber layer 45 and, specifically, to effectively split the wet paper conveyer felt 21 by a heat treatment or a press manufacturing in a carding process, a needling process, and/or a finishing process, which are manufacturing processes of the wet paper conveyer felt 21 itself.

In addition, the wet paper contact fiber layer 45 may be made of a mixture of the splittable fiber 45A having a weight percentage of 15 to 100 wt %, and a non- splittable fiber occupying the remaining portion. The non-splittable fiber refers a typical short fiber that cannot be slit by a carding process, a needling process, or a pressing process using a press device. In addition, the non-splittable fiber preferably includes, for example, a staple fiber having a fineness of 1.9 (i.e., corresponding to the fineness before the splittable fiber is split) to 6 dtex.

As shown in Fig. 5, the wet paper conveyer felt 21 may further include a hydrophilic non-woven layer 53, longitudinally arranged in the first- batt layer 43A and disposed between the base body 41 and the wet paper contact fiber layer 45, and a polymer elastic material 55 impregnated into the wet paper contact fiber layer 45. The hydrophilic non-woven layer 53 is formed of a hydrophilic non-woven structure having a high density by stacking non-splittable fibers having a fineness of, for example, 4 dtex or less, which is smaller than the fibers forming the batt layer 43. Examples of the hydrophilic non-woven structures for forming the hydrophilic non- woven layer 53 are a spun-bond non-woven structure, structured by stacking fibers formed by melting a resin such as nylon and spinning it, for example, by stacking continuous filaments; a non-woven fabric formed by drawing meltable polymer with a hot wind to form filaments and form a sheet shape; and the like.

The polymer elastic member 55 is impregnated into intervals of filaments formed by splitting a plurality of splittable fibers 45A from the wet paper surface side of the wet paper contact fiber layer 45. Specifically, the wet paper contact fiber layer 45 includes a polymer elastic material 55 having a weight percentage of 1 to 10 wt % . The polymer elastic material 55 is formed by splitting a plurality of splittable fibers 45A into filaments using a thermal work or a press work in a carding process, a needling process, and/or a finishing process included in the manufacturing process of the wet paper conveyer belt 21; coating the filaments with a roll or spraying synthetic resin such as aqueous urethane resin, aqueous acrylic resin, aqueous epoxy resin, aqueous synthetic rubber (i.e., an aqueous emulsion resin) in an ambient atmosphere to impregnate it into intervals of the filaments; and curing the material by heating. In this case, since the hydrophilic non-woven layer 53 is disposed on the lower layer of the wet paper fiber layer 45 (i.e., the wet paper side surface of the first batt layer 43A) , the impregnation of the polymer elastic material 55 is obstructed by the hydrophilic non- woven layer 53, so that the first and second batt layers 43A and 43B, and the base body 41 are not impregnated.

Functions of the present embodiment will be described. As shown in Fig. 1, the wet paper W conveyed from the upstream side of the final water-squeezing press rolls 15A and 15B is sucked by the suction roll 61, interposed between the conveyer felt 19 and the wet paper conveyer felt 21 while one side of the wet paper W is held by the conveyer felt 19, and then provided to the water-squeezing rolls 15A and 15B, so that moisture in the wet paper W is squeezed. The finally water-squeezed wet paper W is sucked by the suction roll 63, conveyed while its one side is held by the wet paper conveyer felt 21, and pressed by a pair of transfer rolls 29A and 29B while interposed between the wet paper conveyer felt 21 and the smoothing felt 27. For this reason, the wet paper W is conveyed from the wet paper conveyer felt 21 to the smoothing felt 27. In other words, the wet paper has a characteristic that it is attached to a surface having higher hardness or higher smoothness when the nip pressure is applied to the wet paper W while it is interposed between two sheets of conveyer felts or conveyer belts. Therefore, the wet paper W is surely conveyed by the smoothing belt including the polyurethane layer 33 having a harder and smoother surface than the surface of the wet paper contact fiber layer 45 including the filaments.

The wet paper W is supplied to the smoothing press 17 while its one surface is retained by the smoothing belt 27, and pressed by the first and second press rolls 23 and 25 together with the smoothing belt 27. For this reason, both surfaces of the wet paper W are smoothed. Specifically, one surface of the wet paper W makes contact with the smooth surface of the polyurethane layer 33 of the smoothing belt 27, while the other surface makes contact with the second press roll 25 having a harder and smoother surface so as to be smoothed. As a result, the harshness of both surfaces of the wet paper W can be significantly reduced. In addition, the surface of the wet paper W making contact with the second press roll 25 is somewhat smoothed because the wet paper W includes filaments formed by splitting the splittable fibers 45A since the wet paper W passes through the water-squeezing press rolls 15A and 15B, and the wet paper W is conveyed by the wet paper conveyer felt 21 while it makes contact with the wet paper contact fiber layer 45 having a smooth surface. Therefore, the wet paper W can be more easily and efficiently smoothed by the second press roll 25. In addition, the wet paper W is conveyed to the drier part 13, with the wet paper W being interposed between the canvas 62 and a drier 67, and dried by the drier 67.

According to the smoothing press apparatus 100 of the present embodiment, the nip pressure is applied to the wet paper W by interposing it between the wet paper conveyer felt 21 on which the wet paper contact fiber layer 45 having the splittable fibers 45A is formed and the smoothing felt 27 having the polyurethane surface. As a result, the conveyed wet paper W is surely delivered by the smoothing belt 27 having a hard and smooth surface. In addition, the wet paper W is pressed by a pair of press rolls 23 and 25 together with the smoothing belt 27 having a smooth surface. Thus, both surfaces of the wet paper W, making contact with the smoothing belt 27 and the press roll 25, are smoothed.

In addition, since the polyurethane included in the smoothing belt 27 is made of a material including a particular element, it provides excellent crack resistance, wear resistance, bending fatigue resistance, permanent distortion resistance, and the like. Therefore, the smoothing belt 27 according to the present invention can be used in coarse environments, such as a high speed papermaking and a high pressure press part 11, for a long time. Particularly, the wear resistance of the surface of the smoothing belt 27 is significantly- improved, and few cracks are generated. The wet paper W, which makes contact with the smoothing belt 27 having a smooth surface and is press-ed, has a smoothed surface.

Furthermore, the wet paper conveyer felt 21 includes the base body 41, the first batt layer 43A formed on the wet paper side surface of the base body 41, the second batt layer 43B formed on the roll side surface of the base body 41, and the wet paper contact fiber layer 45 formed on the surface of the wet paper of the first batt layer 43A and including at least the splittable fiber 45A. The wet paper contact fiber layer 45 includes splittable fiber 45A that can be split into very fine filaments. Therefore, it is possible to improve the surface smoothness of the wet paper W.

Furthermore, the wet paper contact fiber layer 45 of the wet paper conveyer felt 21 includes a plurality of splittable fibers 45A that can be split into filaments and a polymer elastic material 55 that has a weight percentage of 1 to 10 wt % and is impregnated into intervals of the filaments. On the wet paper contact fiber layer 45, the wet paper conveyer felt 21 includes a hydrophilic non-woven layer 53 disposed between the first batt layer 43A and the wet paper contact fiber layer 45. Such a construction provides appropriate water permeability, compressive elasticity, and paper separability. Therefore, the wet paper W can be surely conveyed by the smoothing belt 27. Particularly, in the wet paper conveyer felt 21, the hydrophilic non-woven layer 53 disposed between the first batt layer 43A and the wet paper contact fiber layer 45 has a rewetting prevention function to the wet paper W. therefore, the wet paper W is not rewetted when it is conveyed by the smoothing belt 27.

(Second Embodiment)

Now, the second embodiment of the smoothing press apparatus will be described with reference to Figs. 6 to 11.

Fig. 6 is a schematic structural view illustrating a closed draw type paper machine having a smoothing press apparatus according to the second embodiment of the present invention, Figs. 7 (a) to 7 (d) are transverse cross-sectional views illustrating a wet paper conveyer felt having a 3-dimensional woven structure, each of which shows a variation of the embodiment for modifying arrangements of the 3-dimensional woven structure, Fig. 8 is an enlarged view illustrating a 3-dimensional woven structure, of which Fig. 8 (a) is a perspective view illustrating a 3-dimensional woven structure; Fig. 8 (b) is a side view of Fig. 8 (a) illustrated from an arrow B; and Fig. 8 (c) is a side view of Fig. 8 (a) illustrated from an arrow C, Fig. 9 is a side view illustrating a 3- dimensional woven structure, Fig. 10 is a top plan view illustrating a stitch ground of the 3-dimensional woven structure, and Fig. 11 is a top plan view illustrating a stitch ground of the 3-dimensional woven structure.

As shown in Fig. 6, the smoothing press apparatus 200 of the second embodiment has a construction similar to that of the first embodiment except that a suction roll 123^' is provided instead of a pair of transfer rolls 29A and 29B, and the materials of the wet paper conveyer felt 121 and the smoothing belt 127 are different from the first embodiment. Other parts are similar to those of the smoothing press apparatus 100 of the first embodiment. Therefore, like reference numerals designate like elements, and similar parts will not be described providing a simpler description. As shown in Fig. 7, the wet paper conveyer felt 121 includes a base- body 141, a batt layer 143, and a 3- dirαensional woven structure. The base body 141 provides strength to the wet paper conveyer felt 121. The base body 141 may be a woven fabric made by weaving a MD directional yarn material and a CMD directional yarn material, may be an overlapped structure made by overlapping both the MD directional yarn material and the CMD directional yarn material, or may be a construction obtained by winding a fabric having an end, and the like.

The batt layer 143 is a combination of staple fibers. The batt layer 143 is formed by stacking staple fibers on the base body 141 or a 3-dimensional woven layer 151, stacking staple fibers on the base body 141 using a carding device (not shown in the drawing) , and needle-punching them so as to be interlocked. Otherwise, the non-woven layers interlocked by needle-punching only the combination of the staple fibers may be mounted on the base body 141 or the 3-dimensional woven layer 151, and then, a pair of the non-woven layers and the base body 141 or a pair of the non-woven layers and the 3- dimensional woven layer 151 may be needle-punched so as to be interlocked. As shown in Figs. 7 (a) to 7 (d) , various arrangements of the base body 141, the batt layer 143, and the 3-dimensional woven layer 151 may be selected. The wet paper conveyer felt 121 shown in Fig. 7 (a) is made by arranging the base body 141 and the 3-dimensional woven layer 151 to make contact with each other, and the wet paper conveyer felt 121 shown in Fig. 7 (b) is made by interposing the batt layer 143 between the base body 141 and the 3-dimensional woven layer 151. In both the wet paper conveyer felts 121 shown in Figs. 7 (a) and 7 (b) , the wet paper contact fiber layer 145 is provided on the side of the 3-dimensional woven layer 151. In addition, in the wet paper conveyer felts 121 shown in Figs. 7 (c) and 7 (d) , the arrangements of the base body 141 and the 3-dimensional woven layer 151 are reversed, and the wet paper contact fiber layer 145 is disposed on the side of the base body 141.

As^' shown in Fig. 8, the 3-dimensional woven layer 151 includes two stitch grounds- 153 and 155, interlink yarns 157 for interlinking the two stitch grounds 153 and 155. Part of the interlink yarns are crosslinked diagonally. In other words, in the 3-dimensional woven layer 151, the interlink yarns 157 are interlinked between the first and second stitch grounds 153 and 155. In this case, each of the first and second stitch grounds 153 and 155 constituting the 3-dimensional woven layer 151 includes a longitudinal stitch line (i.e., well) continuously pieced in a longitudinal direction of the woven and a lateral stitch line (i.e., a course) continuously pieced in a lateral direction of the woven.

The interlink yarns 157 includes an interlink yarn 157A for interlinking obverse and reverse stitches facing each other in the two stitch grounds 153 and 155 and an interlink yarn 157B (i.e., a crosslink yarn) crosslinked diagonally between the stitches in the well and course line separate from the facing stitches of the obverse and reverse stitch grounds. It should be noted that, in Fig. 8, the first stitch ground 153 is shown as continuously pieced black circles, and the second stitch ground 155 is shown as continuously pieced white circles for convenience .

Far example, the 3-dimensional woven structures 151 known in the art as disclosed in Japanese Unexamined Patent Application Publications Nos. H61-31241, H02- 74648, H02-229247, 2001-234456, and the like may be adopted if they have a construction that part of the interlink yarns 157 are crosslinked diagonally between the first and second stitch grounds 153 and 155. In other words, the first and second stitch grounds 153 and 155 may be appropriately selected from various structures such as a hexagonal shape mesh shown in Fig. 10 or a lozenge shape mesh shown in Fig. 11. In addition, the arrangement of the interlink yarns that are crosslinked diagonallyed may be appropriately selected from various arrangements. For example, as shown in Fig. 9, it is possible to provide a construction in which only the interlink yarns 157 crosslinked diagonally are included.

It is possible to improve compressive elasticity and thickness restorability by installing the 3- dimensional woven layer having such a construction in the wet paper conveyer felt 121. The reason is because the 3-dimensional woven layer 151 has a construction in which the interlink yarns 157 crosslinked diagonally in a thickness direction brace the first and second stitch grounds 153 and 155. Therefore, even when the 3- dimensional woven layer 151 is compressed by a load, the interlink yarns 157 are restored to an original shape in a thickness direction after the load is removed. As a result, compressive elasticity and thickness restorability can be high.

Particularly, when part of the interlink yarns 157 are crosslinked diagonally between the first and second stitch grounds 153 and 155, the compressive elasticity and the thickness restorability can be significantly improved in comparison with when the interlink yarns 157 are not crosslinked diagonally. In addition, it is possible to prevent separation of the interlink yarns when they are compressed because part of the interlink yarns 157 are crosslinked diagonally between the first and second stitch grounds 153 and 155. Furthermore, it is possible to prevent an axis directional rocking motion of the press roll that has been observed in the felt having a 3-dimensional woven structure in which the interlink yarns are not crosslinked diagonally.

The smoothing belt 127 may have a structure similar to the wet paper conveyer felt 21 of the smoothing press apparatus 100 according to the first embodiment that has been described previously in association with Figs. 3 and 5. It will not be described in detail. However, as shown in Figs. 3 and 4, the smoothing belt 127 includes the base body 41, the batt layer 43 (including the first and second batt layers 43A and 43B), and the wet paper contact fiber layer 45. In addition, as shown in Fig. 5, the smoothing belt 127 may further include the hydrophilic non-woven layer 53 longitudinally disposed in the first batt layer 43A between the base body 41 and the wet paper contact fiber layer 45 and may include the polymer elastic material 55 in the wet paper contact fiber layer 45.

The functions of the present embodiment will be described. As shown in Fig. 6, the wet paper W is sucked by the suction roll 61 and one surface of the wet paper W is retained in the conveyer felt 19. The wet paper W is water-squeezed by the water-squeezing press rolls 15A and 15B, sucked by the suction roll 63, and then, conveyed by the wet paper conveyer felt 121. Subsequently, the wet paper W is sucked by the suction roll 123 and delivered from the wet paper conveyer felt 121 to the smoothing belt 127. As described above, the wet paper conveyer felt 121 is a permeable belt including the 3-dimensional woven layer 151, and its surface is relatively harsh.

On the other hand, the smoothing belt 127 has the wet paper contact fiber layer 45 including the filaments formed by splitting the splittable fibers 45A, and the belt's 127 surface is very smooth. The wet paper W can be surely delivered to the smoothing belt 127 by virtue of suction of the suction roll 123 as well as a_. tendency to be attached to a smoother surface when the wet paper W is nipped. In addition, the wet paper W is supplied to the smoothing press 17 while one surface of the wet paper W is retained in the smoothing belt 127, and .the wet paper W is pressed by the first and second press rolls 23 and 25 together with the smoothing belt 127. As a result, both surfaces of the wet paper W are smoothed.

In this case, one surface of the wet paper W makes contact with the very smooth surface of the wet paper contact fiber layer 45 of the smoothing belt 127, and the other surface makes contact with the second press roll 25, whose surface has a high hardness and a high smoothness, so that the wet paper W is smoothed. Therefore, it is possible to obtain the wet paper W, whose surface harshness is very low. The wet paper W is conveyed to the drier part 13 via the canvas 65, and dried in the drier part 67.

According to the smoothing press apparatus 200 of the present embodiment, the wet paper W is conveyed by the wet paper conveyer felt 121 that has permeability and includes^' the base 141, the batt layer 143, and the 3- dimensional woven 151 having two stitch grounds 153 and 155 and interlink yarns 157 crosslinked diagonally between the two stitch grounds 153 and 155. Then, the wet paper W is passed over to the micro-permeable smoothing belt 127 including the wet paper contact fiber layer 45 which directly makes contact with the wet paper W and has at least the splittable fibers 45A.. The wet paper W is also pressed by a pair of press rolls 23 and 25 together with the smoothing belt 127 to smooth the surface of the wet paper. Therefore, it is possible to improve surface smoothness of the wet paper W that makes contact with the wet paper contact fiber layer 45 if the wet paper fiber layer 45 is formed to include the splittable fiber 45A that can be split into the very fine filaments. As a result, it is possible to obtain a very smooth wet paper W.

Furthermore, the wet paper contact fiber layer 45 includes a plurality of splittable fibers 45A split into filaments and a polymer elastic material 55 having a weight percentage of 1 to 10 wt % and impregnated into intervals of the filaments. Therefore, the filaments are somewhat combined by the polymer elastic material 55, so that depilation seldom occurs, and falling-out of the filaments from the smoothing belt 127 is prevented. Therefore, it is possible to obtain a very smooth surface of the wet paper W. In addition, since the smoothing belt 127 has an appropriate restorability (i.e., cushion) , it is possible to provide a large volume of wet paper W.

Furthermore, the fiber for forming the wet paper contact fiber layer 45 is composed of splittable fibers having 15 to 100 weight % and non-splittable fibers occupying the remaining portion. Therefore, it is possible to select the characteristics of the smoothing belt 127 by appropriately changing the mixed ratio between the splittable and non-splittable fibers.

(Third Embodiment)

Now, the smoothing press apparatus according to the third embodiment will be described with reference to Figs. 12 to 14. In addition, the smoothing press apparatus according to the third embodiment has a wet paper conveyer felt different from that of the smoothing press apparatus according to the first embodiment. The other portions are similar to those of the smoothing press apparatus 100 according to the first embodiment. Therefore, like reference numerals designate like elements in order to provide a simplified description.

Figs. 12 (a) to 12 (d) are transverse cross- sectional views illustrating wet paper conveyer felt according to the third embodiment of the present invention, each of which shows a variation of the embodiment for modifying arrangement of a layer including meltable fibers, Fig. 13 is an enlarged cross-sectional view illustrating meltable fibers, and Fig. 14 is a schematic diagram for describing a heat treatment device of the wet paper conveyer felt including meltable fibers.

As shown in Figs. 12 (a) to 12 (d),, the wet paper conveyer felt 221 according to the present embodiment includes a base body 241, a batt layer 243, and a wet paper contact fiber layer 245. More specifically, the first batt layer 243A is formed on the wet paper side surface of the base body 241, and the second batt layer 243B is formed on the roll side or shoe side surface of the base body 241. In addition, the wet paper contact fiber layer 245 is formed on the wet paper side surface of the first batt layer 243A so as to directly contact the wet paper.

As shown in Fig. 12 (a) , the base body 241 allows the wet paper conveyer felt 221 to have strength and may be made of woven materials including synthetic fibers such as nylon 6 or nylon 66 providing excellent wear resistance, fatigue resistance, extendibility, and pollution prevention; natural fibers such as wool; and non-woven materials having an overlapped structure instead of weaving, or a film structure, and the like. The present embodiment adopts wovens as the base body 41. The batt layer 243 (including the first and second batt layers 243A and 243B) is a non-splittable fiber layer formed of staple fibers having a fiber fineness of 6 dtex or more (typically, about 17 dtex) . A material used to form the base body 241 may be appropriately used as a material for forming the batt layer 243. The batt layer 243 is a combination of staple fibers. The batt layer 243 is formed by stacking staple fibers on the base body 241 by using a carding device (not shown in the drawing) and needle-punching them so as to be interlocked. Otherwise, the non-woven layers can be interlocked by needle-punching only the combination of the staple fibers, mounting the combination on the base body 241, and then needle-punching the non-woven layers and the base body 241 so as to be interlocked.

The wet paper contact fiber layer 245 is composed of meltable fibers 249 and non-meltable fibers. Specifically, the meltable fibers 249 may have a weight percentage of 50 wt %, and the non-meltable fibers may occupy the remaining portion (i.e., 50 wt %) . The wet paper contact fiber layer 245 is needle-punched together with the based body 241 so as to be interlocked after the meltable fibers 249 and non-meltable fibers are stacked on the first batt layer 243A. The meltable fiber 249 has a melting point of 200° C or less, preferably 120° C to 180° C, and more preferably in the vicinity of 140° C, and may be made of copolyamide. The non-meltable fiber has a melting point of 200° C to 300° C, preferably 220° C to 260° C, and may be made of nylon 6 or nylon 66. The difference of the melting points of the meltable fiber 249 and the non- meltable fiber may be preferably 60° C or more in order to facilitate the heat treatment work which will be described below. In addition, the melting point is measured by a differential scanning calorimeter.

As shown in Fig. 13, the meltable fiber 249 is a core-in-sheath type meltable fiber 249 having a fiber fineness of 8 dtex. The meltable fiber 249 is formed by coating the outer circumferential surface of the core fiber 251 composed of nylon 6 having a melting point of about 220° C with copolyamide 253 having a melting point of about 140° C. The non-meltable fiber is made of nylon 6 having a fiber fineness of 11 dtex. In addition, the wet paper contact fiber layer 245 may be made of the meltable fibers 249 having a weight percentage of 15 to 100 wt %, and the non-meltable fibers occupying the remaining portion. Furthermore, as another meltable fiber 249, there are exemplified two kinds of composite fibers in German Japanese Unexamined Patent Application Publication No. DE19803493C1.

The arrangement of the fiber layer including the meltable fibers 249 may be selected from various constructions as shown in Figs. 12 (b) to 12 (b) in addition to that shown in Fig. 12 (a) described above. In the wet paper conveyer felt 221 shown in Fig. 12 (b) , the meltable fibers 249 are included in the first and second batt layers 243A and 243B. In the wet paper conveyer felt 221 shown in Fig. 12 (c) , the meltable fibers 249 are included in only the second batt layer 243B. In Fig. 12 (d) , the meltable fiber 249 is included in the wet paper contact fiber layer 245, and the first and second batt layers 243A and 243B.

In the wet paper conveyer felt 221 according to the present embodiment, a layer having a selected composition of fibers is stacked on the base body 241. The layers are needle-punched so as to be interlocked. Therefore, it is possible to form a non-permeable or micro-permeable layer having the meltable fibers 249 even in the inside fiber layer has been difficult to make using a conventional method of impregnating or gluing a polymer material. As a result, it is possible to obtain the wet paper conveyer felt 221 capable of allowing an optimal characteristic for the wet paper to be made.

The wet paper conveyer felt 221 can have proper water permeability by melting the meltable fibers 249 using a heat treatment. In other words, as shown in Fig. 14, the meltable fibers 249 are melted to provide the micro-permeable wet paper conveyer felt 221 when the wet papers pass through the gap between the heat press rolls 255 a plurality of times, while the heat press roll 255 which is an example of a heat treatment device is heated by the heater 254 to about 170° C for 2 to 5 minutes under the pressure of 50 to 70 kg/cm. By appropriately changing the heat treatment work conditions (such as a temperature, a passing number, or a heating time) , it is possible to control solubility of the meltable fibers 249. As a result, it is possible to allow the wet paper conveyer felt 221 to have any characteristic. The wet paper conveyer felt 221 after the heat treatment has a fountain quantity of 1400g/m², a density of 0.480 g/crα³, and a porosity of 8 cc/ (m²* sec) .

The micro-permeable wet paper conveyer felt 221 that has been heat-treated is combined with the smoothing belt 27 shown in Fig. 2 and installed in the smoothing press apparatus 100 shown in Fig. 1 to make paper from the wet paper W. In other words, in association with Fig. 1, the wet paper W conveyed from the water-squeezing rolls 15A and 15B is sucked by the suction roll 61, and one surface of the wet paper W is retained in the conveyer felt 19. Then, the wet paper W is supplied between the water-squeezing rolls 15A and 15B to squeeze water while the wet paper W is interposed between the conveyer felt 19 and the wet paper conveyer felt 221 (or the wet paper conveyer felt 21) . The water-squeezed wet paper W is sucked by the suction roll 63 and conveyed while its one surface is retained in the wet paper conveyer felt 221 or 21. Then, the wet paper W is pressed by a pair of transfer rolls 29A and 29B while it is interposed between the wet paper conveyer felt 221 or 21 and the smoothing felt 27, so that the wet paper W is delivered from the wet paper conveyer felt 221 or 21 to the smoothing belt 27. In addition, the wet paper W is supplied to the smoothing press 17, and pressed by the first and second press rolls 23 and 25 together with the smoothing belt 27, so that both surfaces of the wet paper W are smoothed. Then, the wet paper W is conveyed to the drier part 13 via the canvas 65, and dried by the drier 67.

According to the wet paper conveyer felt 221 of the present embodiment, the wet paper W is conveyed by the micro-permeable wet paper conveyer felt 221 having the wet paper contact fiber layer 245, which contains the meltable fiber 249 and directly makes contact with the wet paper W; is passed over to the non-permeable smoothing belt 27 including the base body 31 and the polyurethane layer 33; and is interposed between a pair of press rolls 23 and 25 together with the smoothing belt 27, so that the surface of the wet paper W is smoothed. The meltable fibers 249 are melted through a heat treatment and are combined with one another, so that the porosity of the wet paper conveyer felt 221 is reduced, and its surface is smoothed. Therefore, by adjusting the heating method, it is possible to obtain the wet paper conveyer felt 221 having water permeability, compressive elasticity (i.e., cushion), and a smoothed surface. In addition, it is possible to smooth the surface of the wet paper W while rewetting is effectively prevented. Furthermore, the wet paper W is surely passed over to the smoothing belt 27 because it is possible to provide excellent paper separability even when the surface of the wet paper conveyer felt 221 is smooth.

In addition, the wet paper conveyer felt 221 includes the meltable fibers 249 in a selected single layer or a plurality of layers in the first and second batt layers 243A and 243B and the wet paper contact fiber layer 245 included in the wet paper conveyer felt 221. As a result, the permeable layer can be formed in a selected layer. In addition, it is possible to easily obtain the wet paper conveyer felt 221 having water permeability and surface smoothness appropriate to the characteristic of the wet paper W to be processed. Furthermore, it is possible to effectively make wet paper W having a smooth surface and excellent paper separability.

Furthermore, since appropriate permeability cannot be obtained when the entire wet paper contact fiber layer 245 is melted, the wet paper contact fiber layer 245 includes partially not melted fibers 249 and melted meltable fibers 249 by virtue of a heat treatment work in which part of the meltable fibers and the non-meltable fibers leave to be not melted. Therefore, it is possible to obtain the wet paper conveyer felt 221 having appropriate permeability and surface smoothness. As a result, it is possible to surely convey the wet paper W to the smoothing belt 27 because excellent paper separability is obtained even when the surface is smooth.

In addition, since the fiber forming the first batt layer 243A, the second batt layer 243B, and the wet paper contact fiber layer 245 containing the meltable fiber 249 includes the meltable fibers 249 having a weight percentage of 15 to 100 wt % and the non-meltable fibers occupying the remaining portion, it is possible to adjust the characteristic of the wet paper conveyer felt 221 by appropriately changing the mixed ratio between the meltable fibers 249 and the non-meltable fibers. This wet paper conveyer felt 221 includes the base body 31 and the polyurethane layer 33 and is suitable to use in combination with the smoothing belt 27 having a smoother surface than that of the wet paper contact fiber layer 245. Furthermore, other functions and effects of the wet paper conveyer felt 221 according to the third embodiment can be easily conceived from the descriptions of the first embodiment.

In addition, the present invention is not limited to the aforementioned embodiments, but any variations or modification can be made appropriately. Besides, materials, shapes, sizes, dimensions, types, numbers, arrangement positions, etc. of each element in the aforementioned embodiments are not provided in a limitative sense but variations can be selected if they can achieve the present invention.

Although the present invention has been described in detail with reference to a particular embodiment, it will be apparent to a person skilled in the art that various modifications or variations can be made without ^• departing from the concept and the scope of the present invention.

The present application claims the benefit of Japanese Patent Applications No. 2005-159965, filed on May 31, 2005, and No. 2005-289138, filed on September 30, 2005, the disclosure of which is incorporated herein in its entirety by reference.

Claims

1. A smoothing press apparatus mounted in a press device provided in a press part of a closed draw type paper machine, the smoothing press apparatus comprising: a first press roll having a smooth surface; a second press roll having a smooth surface and facing the first press roll; a smoothing belt interposed between the first and second press rolls together with wet paper to smooth a surface of the wet paper; and a wet paper conveyer felt for conveying the wet paper and passing over it to the smoothing belt, wherein the wet paper conveyer felt has a wet paper contact fiber layer that includes at least a splittable fiber and directly makes contact with the wet paper, and wherein the smoothing belt includes a base body and a polyurethane layer that directly makes contact with the wet paper.

2. The smoothing press apparatus of Claim 1, wherein polyurethane included in the polyurethane layer of the smoothing belt contains a non-reactive polydimethylsiloxane liquid and has a hardness degree of 90° to 98° in a JIS A hardness standard.

3. The smoothing press apparatus of Claim 1, wherein polyurethane included in the polyurethane layer of the smoothing belt is a mixture of polyurethane having a hardness degree of 90° to 95° in a JIS A hardness standard and containing a non-reactive polydimethylsiloxane liquid and polyurethane having a hardness degree of 95° to 98° in a JIS A hardness standard and not containing a non-reactive polydimethylsiloxane liquid.

4. The smoothing press apparatus of Claim 1, wherein polyurethane included in the polyurethane layer of the smoothing belt is formed by curing a mixture of urethane polymer, a- curing agent, and a non-reactive polydimethylsiloxane liquid having a weight percentage of 0.5 to 25 wt % with respect to a summed amount of the urethane polymer and the curing agent.

5. The smoothing press apparatus of Claim 4, wherein the curing agent is dimethylthiotoluenediamine or methylene-bisorthochloroaniline.

6. The smoothing press apparatus of any one of Claims 1-5, wherein the wet paper conveyer felt comprises : a base body; a first batt layer formed on a surface of the wet paper side of the base body; a second batt layer formed on a surface of the roll side of the base body; and a wet paper contact fiber layer including a splittable fiber and formed on a surface of the wet paper side of the first batt layer to directly make contact with the wet paper.

7 The smoothing press apparatus of any one of Claims 1-5, wherein the wet paper conveyer felt comprises : a base body; a first batt layer formed on a surface of the wet paper side of the base body; a second batt layer formed on a surface of the roll side of the base body; a wet paper contact fiber layer including a plurality of splittable fibers split into filaments and a polymer elastic material impregnated into intervals of the filaments, the wet paper contact fiber layer being formed on a surface of the wet paper side of the first batt layer so that the filaments and the polymer elastic material directly make contact with the wet paper; and a hydrophilic non-woven layer disposed between the first batt layer and the wet paper contact fiber layer.

8. The smoothing press apparatus of Claim 7, wherein the polymer elastic material contained in the wet paper contact fiber layer has a weight percentage of 1 to 10 wt %.

9. The smoothing press apparatus of any one of Claims 6-8, wherein the fiber contained in the wet paper contact fiber layer is composed of a splittable fiber having a weight percentage of 15 to 100 wt % and a non- splittable fiber occupying the remaining portion.

10. The smoothing press apparatus of any one of Claims 6-9, wherein the splittable fiber has a fiber fineness of 3.3 dtex or less before splitting.

11. A smoothing press apparatus mounted in a press device provided in a press part of a closed draw type paper machine, the smoothing press apparatus comprising: a first press roll having a smooth surface; a second press roll having a smooth surface and facing the first press roll; a smoothing belt interposed between the first and second press rolls together with wet paper to smooth a surface of the wet paper; and a wet paper conveyer felt for conveying the wet paper and passing over it to the smoothing belt, wherein the wet paper conveyer felt has a 3- dimensional woven structure including a base body, a batt layer, two stitch grounds, and interlink yarns for interlinking the two stitch grounds, part of the interlink yarns being crosslinked diagonally, and wherein the smoothing belt includes at least a wet paper contact fiber layer that includes a splittable fiber and directly makes contact with the wet paper.

12. The smoothing press apparatus of Claim 11, wherein the smoothing belt comprises : a base body; a first batt layer formed on a surface of the wet paper side of the base body; a second batt layer formed on a surface of the roll side of the base body; and a wet paper contact fiber layer including a splittable fiber and formed on a surface of the wet paper side of the first batt layer, the wet paper contact fiber layer directly making contact with the wet paper.

13. The smoothing press apparatus of Claim 11, wherein the smoothing belt comprises: a base body; a first batt layer formed on a surface of the wet paper side of the base body; a second batt layer formed on a surface of the roll side of the base body; and a wet paper contact fiber layer including a plurality of splittable fibers split into filaments and a polymer elastic material impregnated into intervals of the filaments, the wet paper contact fiber layer being formed on a surface of the wet paper side of the first batt layer so that the filaments and the polymer elastic material directly make contact with the wet paper; and a hydrophilic non-woven layer disposed between the first batt layer and the wet paper contact fiber layer.

14. The smoothing press apparatus of Claim 13, wherein the polymer elastic material contained in the wet paper contact fiber layer has a weight percentage of 1 to 10 wt %.

15. The smoothing press apparatus of any one of Claims 11-14, wherein the fiber contained in the wet paper contact fiber layer is composed of a splittable fiber having a weight percentage of 15 to 100 wt % and a non-splittable fiber occupying the remaining portion.

16. The smoothing press apparatus of any one of Claims 11-15, wherein the splittable fiber has a fiber fineness of 3.3 dtex or less before splitting.

17. A smoothing press apparatus mounted in a press device provided in a press part of a closed draw type paper machine, the smoothing press apparatus comprises : a first press roll having a smooth surface; a second press roll having a smooth surface and facing the first press roll; a smoothing belt interposed between the first and second press rolls together with wet paper to smooth a surface of the wet paper; and a wet paper conveyer felt for conveying the wet paper and passing over it to the smoothing belt, wherein the wet paper conveyer felt has a wet paper contact fiber layer that includes at least a meltable fiber and directly makes contact with the wet paper, and wherein the smoothing belt includes a base body and a polyurethane layer that directly makes contact with the wet paper.

18. The smoothing press apparatus of Claim 17, wherein the wet paper conveyer felt comprises: a base body; a first batt layer formed on a surface of the wet paper side of the base body; a second batt layer formed on a surface of the roll side of the base body; and a wet paper contact fiber layer including a meltable fiber and formed on a surface of the wet paper side of the first batt layer, the wet paper contact fiber layer directly making contact with the wet paper.

19. The smoothing press apparatus of Claim 17, wherein the wet paper conveyer felt comprises: a base body; a first batt layer formed on a surface of the wet paper side of the base body and including the meltable fiber; a second batt layer formed on a surface of the roll side of the base body and including the meltable fiber; and a wet paper contact fiber layer formed on a surface of the wet paper side of the first batt layer, the wet paper contact fiber layer directly making contact with the wet paper.

20. The smoothing press apparatus of Claim 17, wherein the wet paper conveyer felt comprises: a base body; a first batt layer formed on a surface of the wet paper side of the base body; a second batt layer formed on a surface of the roll side of the base body and including the meltable fiber; and a wet paper contact fiber layer formed on a surface of the wet paper side of the first batt layer, the wet paper contact fiber layer directly making contact with the wet paper.

21. The smoothing press apparatus of Claim 17, wherein the wet paper conveyer felt comprises : a base body; a first batt layer formed on a surface of the wet paper side of the base body and including the meltable fiber; a second batt layer formed on a surface of the roll side of the base body and including the meltable fiber; and a wet paper contact fiber layer including the meltable fiber and formed on a surface of the wet paper side of the first batt layer, the wet paper contact fiber layer directly making contact with the wet paper.

22. The smoothing press apparatus of any one of Claims 17, 18, and 21, wherein the wet paper conveyer felt comprises: a base body; a first batt layer formed on a surface of the wet paper side of the base body; a second batt layer formed on a surface of the roll side of the base body; and a wet paper contact fiber layer including the meltable fiber melted with a thermal work and formed on a surface of the wet paper side of the first batt layer so that the meltable fiber can make directly contact with the wet paper.

23. The smoothing press apparatus of any one of Claims 17-22, wherein the fiber for forming the first batt layer, the second batt layer and the wet paper contact _ fiber layer containing the meltable fiber includes a meltable fiber having a weight percentage of 15 to 100 wt % and a non-meltable fiber occupying the remaining portion.