JP2007277783A - Press device for papermaking - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a shoe press device providing excellent water-squeezing properties and paper quality of wet paper in the production of thin paper by an optimum combination of characteristics of both of a press felt for papermaking and a press belt for the papermaking. <P>SOLUTION: The press device providing the good water-squeezing properties and paper quality of the wet paper is obtained by attaching the press felt (50) for the papermaking and the press belt for the papermaking having optimum void volumes. Especially, the press device makes the press felt mainly bear the role for improving smoothness and strength of the paper, and the press belt mainly bear the role for improving the water-squeezing properties. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a papermaking shoe press apparatus (hereinafter, simply referred to as “shoe press apparatus”) for producing thin paper.
In particular, in order to improve the water squeezability and paper quality of thin paper, a papermaking tool to be used [paper press felt (hereinafter simply referred to as “press felt”) and paper press belt (hereinafter simply referred to as “press belt”). ] Is optimally combined.

  In order to squeeze water from the wet paper in the paper making process, a paper machine has conventionally been provided with a wire part, a press part, and a dryer part. These wire part, press part, and dryer part are arranged along the conveyance direction of the wet paper in this arrangement order. The wet paper is transported and squeezed out (i.e., squeezed) after being transferred to the paper making tools arranged in the wire part, the press part, and the dryer part, and finally the dryer. Dried in part. The press device disposed in the press part includes a plurality of press devices arranged in series along the wet paper web transfer direction. Each press device includes a pair of endless belt-like press felts and a pair of rolls (that is, a roll press) or a roll and a shoe (press and shoe) that are vertically opposed so as to sandwich a part of each press felt. That is, by pressing the wet paper transported by the press felt that travels in the same direction at substantially the same speed with a roll and a roll or a roll and a shoe together with the press felt, While pressing water from the wet paper, the press felt absorbs the water. In such a paper machine, a roll press type paper machine in which a press device that presses a part of a press felt that sandwiches wet paper between the roll and the roll is provided in the press part sandwiches the wet paper. There is a shoe press type paper machine in which a press device that presses a part of a press felt while being sandwiched between a roll and a shoe is provided in a press part.

  In particular, with a shoe press type paper machine, a press zone (that is, a nip formed by a roll and a shoe) has a wider press zone than that of a more general roll press type paper machine. Since the time can be extended, the water squeezing is more excellent.

  The amount of waste water squeezed in this way varies depending on the press pressure, the running speed of the papermaking tool, and the paper quality. A press felt and a press belt used in such a press apparatus (for example, Document 1) will be briefly described.

  The press felt includes a base layer and a butt layer, and the bat layer includes a wet paper web side layer and a press side layer. At this time, the bat layer is configured to be endless by tangling and integrating the bat fiber with the base layer by needle punching. Press felt improves the basic characteristics of transporting wet paper to the next process (drying process) and smoothness of the paper, mitigates impact during pressing and prevents paper breakage, and further improves water squeezability. It plays important functions such as pressure uniformity and water permeability.

  The press belt includes a polymer elastic member such as urethane and a base layer for reinforcing the polymer elastic member. It has physical and chemical durability due to the polymer elastic member that constitutes the press belt. Water permeability or void volume (hereinafter referred to as void volume) due to the function of drainage grooves and holes provided on the felt contact surface side. Can be maintained for a long time.

  However, with the recent increase in nip pressure and increase in the speed of the paper machine as a whole, the amount of water remaining in the press part has increased, which has hindered the improvement of water extraction efficiency. That is, since the wet paper passes through the nip width of the press part through the press felt and the press belt for a very short time, the amount of water discharged from the press part to the outside of the system is limited.

However, in the conventional papermaking tool, the press felt component and the press belt component are completely separate. In other words, the constituent elements of the press felt were intended to increase the strength and durability of the base layer, increase the ratio of the base layer in order to improve water squeezing, and increase the basis weight to increase the void volume.
On the other hand, the constituent elements of the press belt are to increase the strength and durability of the base layer, to increase the strength and durability of the polymer elastic member, and to change the shape and dimensions of the drainage grooves to improve the water squeezing, thereby reducing the void volume. The purpose was to increase.

Conventionally, the components of the press felt and the press belt have been separately performed as described above, and thus, in the manufacture of thin paper (lightweight paper having a paper basis weight in the range of 10 to 80 g / m 2), it has a negative effect. There was a thing. That is, when producing thin paper with a shoe press device, if there is too much void volume of the press felt, the pressure transmission force to the wet paper in the press zone will be reduced, and the required water squeezing will not be obtained. There was a thing.
Or, due to insufficient water extraction in the press zone, that is, insufficient void volume between the press felt and the press belt, the moisture and smoothness of the wet paper deteriorate, or the wet paper breaks in the press zone. There was also.

Conventionally, Document 2 has introduced an evaluation of dewatering (squeezing) characteristics for a combination of a press felt and a press belt in a shoe press apparatus, and a measuring instrument therefor. Here, it is clearly shown that the optimum condition of the press belt changes depending on the structure of the press felt to be combined.
However, the void volume incompatibility of papermaking tools affects the paper quality and water squeezability of wet paper. In other words, the problem of increasing the amount of steam used in the drying process while impairing the smoothness of the wet paper, and the incompatibility of the void volume of the papermaking tool remained the above-mentioned problems of the wet paper's paper quality and impact on squeezing ability. .
This means that in a shoe press device, it is not appropriate to accept the amount of water squeezed from wet paper only with felt, and there is a problem that water flow must be controlled by both the press felt and the press belt. Yes. There are no proposals or descriptions about these problems and their countermeasures in Document 2.
In other words, in the conventional press felt, the idea of sharing the void volume necessary for water squeezing was common, so the set basis weight (g / cm 2) of the press felt inevitably becomes excessive, The required pressure transmission during press was greatly negative.

Reference 1

  JP-A-60-215893

Reference 2

  86th ANNUAL MEETING, PAPTAC (B61-B65)

In view of the above-mentioned problems in the shoe press apparatus, the present invention skillfully combines the characteristics of both the press felt and the press belt, and provides excellent water squeezing and wet paper for the production of thin paper by optimal combination of both under the press. An object of the present invention is to provide a shoe press apparatus having a paper quality of 5 mm.
In particular, in the present invention, the press felt mainly plays a role of improving the smoothness and strength of the paper (that is, improving the paper quality), and the water squeezing (void volume and water permeability) necessary for squeezing is mainly shared by the press belt. An object of the present invention is to provide a shoe press apparatus.

  The present invention is equipped with a press felt provided with a butt layer on the wet paper side layer and the press side layer of the base layer, and a press belt provided with a polyurethane resin layer on both sides of the base layer and provided with a drain groove on the press felt side. In the above shoe press apparatus, the void volume in a pressurized state at a press pressure of 30 kg / cm 2 is in the range of 250 to 650 cc / m 2 for the press felt, and in the range of 250 to 550 cc / m 2 for the press belt. This is a shoe press device for producing thin paper.

  Furthermore, it is preferable as a shoe press device for producing thin paper that the total void volume of the press felt and the press belt is in the range of 650 to 1050 cc / m2.

  Here, the basis weight of the thin paper is particularly preferably in the range of 10 to 80 g / m 2 as a shoe press device for producing thin paper. The thin paper can be applied to a thin paper with a light basis weight such as tissue paper with a basis weight of 12 g / m 2, newspaper with a weight of 46 g / m 2, and high-quality paper with a weight of 70 g / m 2.

  A shoe press device comprising a first press device for transporting wet paper with a press felt and squeezing water from the wet paper and a second press device provided downstream thereof, wherein the press felt 1 according to claim 1 is used. A shoe press device is suitable, in which one or more sheets and a press belt are used in the first or second press device or in the first and second press devices.

  Furthermore, in the shoe press apparatus provided only with the No. 1 press apparatus which conveys a wet paper with a press felt and squeezes water from the wet paper, one or more press felts according to claim 1 and a press belt are attached to the No. 1 press apparatus. A shoe press device may be used.

  The present invention is most preferably characterized in that it is used in a shoe press device provided in a press part of a closed draw type paper machine.

    According to the present invention, a combination of a press felt having an optimal void volume and a press belt is mounted on a press device for producing thin paper, so that wet paper squeezing performance and paper quality are particularly good during thin paper production. There is an effect that a press device can be provided.

  An embodiment of the press felt of the present invention will be described with reference to FIG. In addition, FIG. 1 is a cross-machine direction (CMD) sectional view of the press felt. In FIG. 1, a press felt 50 is composed of a base layer 60 and a butt layer 70, which are intertwined and integrated by needle punching.

  The base layer 60 is provided in order to express the strength of the press felt, and as the material thereof, a woven fabric, a non-woven fabric having a bat layer on a parallel thread arrangement, or a yarn material overlapped without being woven. Various materials proposed by those skilled in the art, such as a non-woven base material and a film, can be used as appropriate. Although the example of the woven fabric is described in FIG. 1, it is not limited to this.

The batt layer 70 is composed of staple fibers 80, and includes a wet paper web side layer 71 and a press side layer 72. At this time, of course, the staple fiber 80 is also disposed in the base layer 60.
As the staple fiber 80 constituting the batt layer 70, fibers having a fineness of 6 dtex (dtex) or more are used, and those having a density of about 17 dtex (dtex) are generally used.

As the material for the base layer 60 and the bat layer 70, natural fibers such as wool or synthetic fibers such as nylon 6 and nylon 66 having excellent wear resistance, fatigue resistance, stretch characteristics, antifouling properties, etc. are used. The
The void volume of the press felt of the present invention means the volume of the press felt voids (per unit area of the press felt) in an air-dried pressurized state.

  Next, an embodiment of the press belt 10 will be described with reference to FIG. FIG. 2 shows a CMD cross-sectional view of the belt 10. The press belt 10 has a polyurethane resin layer 20 formed on both sides of a base layer 30.

  The base layer 30 is provided in order to develop the strength of the press belt 10, and as a material thereof, a woven fabric, a non-woven fabric in which a batt layer is arranged in parallel to each other, or a yarn material is overlapped without being woven. Various materials proposed by those skilled in the art, such as a non-woven base material and a film having a different structure, can be used as appropriate. Although the example of the woven fabric is described in FIG. 2, it is not limited to this.

A large number of drain grooves 33 are provided on the surface 11 of the press felt side resin 21 of the belt 10 in the running direction of the belt. This drainage groove serves to discharge the moisture squeezed out when the wet paper passes through the press zone of the shoe press device. Further, the shoe side resin 22 of the belt 10 contacts the press shoe.
The void volume of the press belt of the present invention means the volume (per unit area of the press belt) of the drain groove of the press belt in an air-dried pressurized state.

  The groove width of the drainage groove 33 is 0.5 to 2 mm, preferably 0.8 to 1.2 mm, and the depth c is 0.5 m to 5 mm, preferably 1 to 2 mm. Is 1 to 4 mm, preferably 2 to 3 mm. Chamfering can be applied to the end portion of the land portion.

  FIG. 3 is a schematic view showing an embodiment of a press apparatus for producing thin paper, in which the press felt of the present invention and a press belt are combined. The press device 300 includes a first press device 51 that sandwiches the wet paper W between the two sets of press felts 100 and 100 and the press felts 200 and 200 and squeezes water from the wet paper W, and 2 provided downstream thereof. And a number press device 53.

  Further, shoe press devices 55 and 59 are provided on the upper stage (top side) of the first press apparatus 51 and the second press apparatus 53 in FIG. 3, respectively, and press rolls 57 and 61 are provided on the lower stage (bottom side). Each shoe press apparatus is equipped with a press belt.

  Further, even if the press felt 50 of FIG. 1 and the press belt 10 of FIG. 2 are used in either the first press device 51 or the second press device 53 of FIG. 3, the first press device 51 and the second press device 53 It may be used for both.

Here, the void volume of the press felt and the press belt will be described.
The following formula can be used for the void volume (VV) of the press felt in an air-dried state with a press pressure of 30 kg / cm 2.
formula;
Press felt VV (cc / m 2) = (Press felt thickness under pressure) × 1000− [Press felt basis weight (g / m 2) /1.14]
Here, the numerical value 1.14 is the specific gravity of the material when nylon is used as the material of the base layer and the bat layer of the press felt. Therefore, when other materials are used, the ratio of each material may be calculated and the average specific gravity applied.
Further, the void volume (VV) of the press belt in an air-dried and pressurized state with a press pressure of 30 kg / cm 2 is obtained by calculating the drain groove area on the press belt surface and the groove depth of the CMD section in the press state. The amount of voids per area (m2) is calculated.

Next, an embodiment of an optimum combination of a press felt and a press belt to be mounted on the press apparatus when producing thin paper with the press apparatus will be described. However, the specific gravity of water is 1 (1 cc = 1 g).
(1) Basis weight of thin paper: 12 g / m 2 (tissue), 46 g / m 2 (newspaper), 70 g / m 2 (quality paper) were produced according to the present invention.
(2) Shoe press device: A closed / draw type shoe press device as shown in FIG. 3, comprising a first press device and a second press device.
(3) Driving speed of the shoe press device. ・ Runs at a speed of 1400, 1600, 2000 m / min.
(4) Press felt: An experiment was conducted in which a press felt having various void volumes and a press belt were combined under the above conditions (1) to (3). From the experimental results, the range of press felts with the optimal void volume (VV) when used with a press belt is listed in the table.
(5) Press belt: The range of press belts having the optimum void volume (VV) when used together with the press felt for use under the conditions (1) to (4) above is described in the table.

  In the table, it is not necessary to use a No. 2 press device when producing a tissue paper having a basis weight of 12 g / m 2. In the No. 1 press device, one press felt in the table and a press belt in each range have a void volume. If it has, it was possible to produce a stable thin paper. However, when it was below the lower limit value of each range, paper breakage in the press zone was remarkable and wet paper smoothness was poor. And when the upper limit of each range was exceeded, as a result of insufficient pressure transmission force to the wet paper in the press zone, water squeezing was poor.

In the table, when producing high-quality paper with a basis weight of 46 g / m 2 and a high-quality paper with a basis weight of 70 g / m 2, even if the void volume of the press felt is within the range shown in the table, the void volume of the press belt is It was found that when the upper limit value 550 (cc / m 2) was exceeded, the shape of the drainage groove of the press belt was transferred to the wet paper, thereby affecting the paper quality, that is, the wet paper smoothness.
In addition, even if the total void volume of the press felt and the press belt is within the range of 650 (cc / m2) to 1050 (cc / m2), the range of 250 to 650 (cc / m2) with one press felt, From the experimental results, it was found that when the press belt satisfies the range of 250 to 550 cc / m 2 at the same time, the squeezing ability cannot be maintained.

  CMD sectional drawing of the embodiment of the press felt of this invention.   The CMD sectional view of the embodiment of the press belt of the present invention.   1 is a schematic diagram of a press apparatus equipped with a press felt and a press belt according to the present invention.

Explanation of symbols

50: Press felt 60: Base layer 70: Bat layer 71: Wet paper side layer 72: Press side layer 80: Staple fiber 10: Press belt 11: Surface 20: Polyurethane resin layer 21: Press felt side resin 22: Shoe side resin 30 : Base layer 33: Drainage groove 300: Press device 51: No. 1 press device 51
53: No. 2 press machine 53
55, 59: Shoe press device 57, 61: Press roll 100, 200: Press felt W: Wet paper A: Direction of movement of wet paper

Claims (6)

  A papermaking press felt having a butt layer on a wet paper side layer and a press side layer of the base layer, a polyurethane resin layer on both sides of the base layer, and a paper press belt having a drainage groove on the paper press felt side; The void volume in a pressurized state at a press pressure of 30 kg / cm 2 is in the range of 250 to 650 cc / m 2 for the paper press felt, and 250 to 550 cc / m for the paper press belt. A papermaking shoe press device for producing thin paper, characterized by being in the range of m2.   2. The papermaking shoe press for producing thin paper according to claim 1, wherein the sum of void volumes of the papermaking press felt and the papermaking press belt is in the range of 650 to 1050 cc / m2. apparatus.   3. The papermaking shoe press device for producing thin paper according to claim 1, wherein the basis weight of the thin paper is in a range of 10 to 80 g / m <2>. In a papermaking shoe press device comprising a first press device for transporting wet paper by a papermaking press felt and squeezing water from the wet paper and a second press device provided downstream thereof,
A papermaking shoe press apparatus for producing thin paper, wherein one or more papermaking press felts and a press belt according to claim 1 are used in the first or second press apparatus. In a shoe press device for a paper machine comprising a first press device for transporting wet paper with a paper press felt and squeezing water from the wet paper and a second press device provided downstream thereof,
A shoe press apparatus for papermaking for producing thin paper, wherein one or more press felts for papermaking and a press belt for papermaking are used in the first and second press apparatuses. In a shoe press device for a paper machine comprising only a No. 1 press device for transporting wet paper with a paper press felt and squeezing water from the wet paper,
A papermaking shoe press apparatus for producing thin paper, characterized in that the two papermaking press felts and the papermaking press belt according to claim 1 are used in the No. 1 press apparatus.

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