JP3472483B2 - Felt for papermaking and method for producing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention particularly relates to a felt for papermaking which is pressed by a press section of a papermaking machine to squeeze water from a wet paper sheet and a method for producing the felt.

[0002]

2. Description of the Related Art Recent papermaking techniques are required to maintain paper surface while high speed and high nip pressure are progressing. In order to satisfy this demand, it must be able to contribute to the performance of the papermaking felt, that is, to increase and maintain the void volume under a high nip and to improve the paper surface.

The void volume (V.V) is 1
It is the amount of felt voids per m ^{2 and} can be determined by the following equation. V. V (cc / m ² ) = T × 1000−felt basis weight /
ρ In the above equation, “T” is the felt thickness (mm) under a constant load, “felt basis weight” is g / m ² , and ρ is the density of the felt material (g / cm ³ ).

As a technique for increasing the void volume, Japanese Patent Application No. 56-60686 and Japanese Patent Application No. 56-
A felt for papermaking using a base fabric in which a plurality of woven fabrics are superposed is known as in No. 160765.

[0005]

However, in the base fabric 3 of the above-mentioned pile type papermaking felt, as shown in FIGS. 5 and 6, two woven fabrics in the longitudinal direction (the same in the transverse direction) are used. Since the contact surfaces 5 between the woven cloths 2a and 2b are aligned in parallel,
A ridge-shaped convex portion A of the lengthwise thread W ₁ of the overlapping woven fabric 2a
But easily enter the ridged recess B between length direction yarns W ₂ of the other woven fabric 2b, therefore, the following disadvantages were present.

That is, as a felt for papermaking, when it is used under pressure, it tends to be crushed, the void volume is reduced, and the water squeezing function is reduced early. By overlapping the woven cloth, the number of threads in the upper woven cloth that intervenes between the threads in the lower woven cloth becomes uneven, and interference patterns (speckle patterns) occur, impairing the surface smoothness of the felt, and Interference marks (speckle marks) were generated, and the uniformity was reduced.

An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide a felt for papermaking which can contribute to increase and maintenance of void volume and improvement of paper texture, and a manufacturing method thereof. And

[0008]

In order to achieve the above object, a felt for papermaking according to the present invention is a papermaking obtained by needling a fibrous web on one or both sides of a base fabric in which a plurality of woven fabrics are laminated. In the felt, the woven fabric of each layer constituting the base fabric is formed by endlessly joining both ends in the length direction of the endless woven fabric, and when joining both ends of the woven fabric, While sliding and joining in the direction,
The ridges of the lengthwise threads of one of the overlapping woven fabrics are characterized by the fact that the lengthwise threads are relatively obliquely intersected at the contact surface between the woven fabrics by making the shifting direction relatively different for each layer. The convex portion of the woven fabric is configured so as not to enter the ridge-shaped recess formed between the lengthwise yarns of the other woven fabric.

In the felt for papermaking according to the second aspect of the present invention, the base fabric is composed of two woven fabrics, and the lengthwise yarns of the two woven fabrics are arranged in the machine direction. It is characterized by being symmetrically crossed left and right, and is configured so that the running of the felt is balanced left and right with respect to the machine flow direction.

Further, in the papermaking felt according to the third aspect of the present invention, the base fabric is composed of three woven fabrics, and the lengthwise yarns of one woven fabric of the intermediate layer are arranged in the machine flow direction. It is characterized in that the lengthwise threads of the two woven fabrics of the front and back layers are diagonally crossed symmetrically with respect to the lengthwise yarn of the woven fabric of the middle layer.
The strength of the machine is maintained in the machine direction, and the running of the felt is balanced left and right with respect to the machine direction.

Furthermore, a method of manufacturing a felt for papermaking according to the fourth aspect of the present invention is a method of manufacturing a plurality of endless woven fabrics.
In the method for producing a felt for papermaking in which a fiber web is needling on one side or both sides of an endless base fabric that is endlessly joined by abutting both ends in the length direction, when joining both ends of the woven fabric of each layer, The structure is characterized in that the layers are slidably joined in the width direction, and the slidable directions are relatively different for each layer, so that the oblique crossing at the contact surface between the woven fabrics can be easily obtained.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings. 1 is a sectional view schematically showing the felt of the present application, FIG. 2 is a plan view schematically showing a laminated state of two woven fabrics, FIG. 3 is a side sectional view of the same, and FIG. 4 is two woven fabrics. FIG. 9 is a perspective view schematically showing a state in which the two ends of the plate are displaced in the width direction when they are abutted and joined to each other.

In FIG. 1, the felt 1 of the present invention has a fibrous web 4 placed on one side (or both sides) of a base fabric 3 in which a plurality of (two cases are shown) woven fabrics 2a and 2b are laminated. Needling (not shown), and the base fabric 3 has the longitudinal threads W ₁ and W ₂ of the woven fabrics 2a and 2b constituting the base fabric 3 slanted at the contact surface 5 between the woven fabrics. I have 6 exchanges. The portion of the oblique intersection 6 is shown by hatching in FIG.

The lengthwise threads W ₁ and W _{2 of the} woven fabrics 2a, 2b
2, the inclination angles θ ₁ and θ ₂ are symmetrical with respect to the machine flow direction P. This allows the running of the felt 1 of the present application to be balanced left and right with respect to the flow direction of the machine, and does not shift to the right or left during running.

The lengthwise threads W ₁ and W _{2 of the} woven fabrics 2a, 2b
As shown in FIG. 3, the reason why the 6 and 6 are obliquely crossed is that the lower woven cloth 2b is
The ridge-shaped concave portion B formed by the lengthwise-direction thread W ₁ of the upper woven fabric 2b is prevented from entering the ridge-shaped recess B formed by the lengthwise-direction thread W ₂ and the void volume is maintained for a long time. This is so that it can be maintained.

Although not shown in the drawings, the felt 1 of the present application may be composed of a base fabric obtained by laminating three woven fabrics. In this case, match the lengthwise yarn of one woven fabric in the middle layer with the machine direction and make the lengthwise yarns of two woven fabrics in the front and back layers relative to the lengthwise yarn of the middle woven fabric. It is advisable to make the inclination angle symmetrical with respect to the left and right sides and to make it cross. In other words, one woven fabric in the middle layer is responsible for maintaining the strength in the machine flow direction, and the two woven fabrics in the front and back layers are made to have a symmetrical inclination so that they do not shift to the right or left during traveling. Is.

The lengthwise yarn W _{1 of the} two woven fabrics 2a, 2b
The following is a method of obliquely mixing 6 and W ₂ (the same procedure can be applied to three woven fabrics). That is, as shown in FIG. 4, both ends 2a 'and 2a ", 2b' and 2b" of the woven fabric (end-shaped) 2a, 2b are used.
When they are abutted and joined to each other, they are displaced in the width direction S-S ', and the displacement direction is relatively different for each layer.

For example, in the woven cloth 2a, one end 2a 'is left (S
Direction), the other end 2a ″ is slid to the right (S ′ direction). In the woven fabric 2b, one end 2b ′ is slid to the right (S ′ direction) and the other end 2b ″ is slid to the left (S direction). By doing so, it becomes possible to easily cross 6 the lengthwise threads W ₁ and W _{2 of the} woven fabrics 2a and 2b.

The inclination angles θ ₁ and θ ₂ of the lengthwise yarns W ₁ and W ₂ with respect to the machine flow direction P are determined by the deviations L ₁ and L ₂ when the joining points of the woven fabrics 2a and 2b are laterally displaced. Each is decided. It is necessary for the inclination angles θ ₁ and θ ₂ to be acute in order to maintain the strength in the machine flow direction, but if the angle is too acute, the void volume tends to collapse, while if it is too obtuse the machine maintains strength in the machine direction. Dissatisfaction occurs. Specifically, θ ₁ or θ ₂ = about 1 to 8 °, preferably 1.5 to 5 ° (angle between the lengthwise yarns (θ
_If converted to ₁ + θ ₂ ), it will be 3 to 10 °), which is sufficiently satisfactory.

[0020]

Example 1 Two woven fabrics 2a (upper fabric) and 2b described below
(Bottom cloth) was used to prepare a base cloth 3 in which the lengthwise threads W ₁ and W ₂ were obliquely crossed.

[0021]   Top cloth   Warp: Nylon monofilament 220d × 4 twisted yarn 50 / 5cm   Weft: Nylon monofilament 500d 50 pieces / 5cm   Woven structure: plain weave

[0022]   Undercloth   Warp: Nylon monofilament 330d x 6 twisted yarns 42 / 5cm   Weft: Nylon monofilament 330d x 4 twisted yarns 40 / 5cm   Woven structure: 3/1 collapse

The length direction threads of the upper cloth and the lower cloth (corresponding to the warp,
W ₁ and W ₂ are 1.5 ° with respect to the machine flow direction P (the angle between the lengthwise threads is 3)
°).

[0024]

[Example 2] Using the same two woven fabrics 2a (upper fabric) and 2b (lower fabric) as in Example 1, a base fabric 3 was prepared in which the angles of the lengthwise threads were obliquely set to 6 °. did.

[0025]

Example 3 Using the same two woven fabrics 2a (upper fabric) and 2b (lower fabric) as in Example 1, prepare a base fabric 3 in which the angles of the lengthwise threads are obliquely set to 10 °. did.

[0026]

[Comparative Example 1] A base cloth 3 in which the same two woven cloths 2a (upper cloth) and 2b (lower cloth) as in Example 1 were used, and the angles between the longitudinal threads were 0 ° (not oblique). Prepared.

Regarding Examples 1 to 3 and Comparative Example 1,
The following three tests were conducted. That is, confirmation of the effect of reducing interference marks generated by overlapping the base cloth,
Confirm the effect of increased void volume by stacking base fabrics, and confirm the effect of maintaining void volume by stacking base fabrics.

Confirmation of Effect of Reducing Interference Marks 100 g / m ² ± 5 g / m ^{2 of} nylon 13d (average) on the base fabric of Examples 1 to 3 and Comparative Example 1 above.
Put 1 to 12 bats adjusted to ² , and overlay carbon transfer paper for mark evaluation on it, and transferability after roll pressure of 30 kg / cm ² , that is, erase base cloth mark / interference mark When the number of bats required for was measured, Example 1 = 10, Example 2 = 9, Example 3 = 9, and Comparative Example 1 = 12. As a result, it was confirmed that Examples 1 to 3 had a higher effect of reducing the base cloth mark / interference mark than Comparative Example 1.

Confirmation of Effect of Void Volume Standard base bat 105 g / m ^{2 made of} nylon 13d (average) on the base fabric made in Examples 1 to 3 and Comparative Example 1
6 layers on the front side and 2 layers on the back side are entangled and integrated by a needle punch, and then passed through a 140 ° C. heat roll at a cloth speed of 2 m / min and a pressure of 20 kg / cm ² for about 150
A test sample of 0 g / m ² was prepared.

The above sample was immersed in distilled water at 20 ° C. ± 2 ° C. for 1 hour and then a pressure of 30 kg / cm ² was applied by a compression tester (not shown) to measure the thickness and to determine the void volume. confirmed. The results are shown in the table below.

[Table] Example 1 Example 2 Example 3 Comparative Example 1 Sample basis weight (g / m ² ) 1512 1520 1522 1510 Pressurized thickness (mm) 2.24 2.29 2.30 2. 19 V. V (cc / m ² ) 914 957 965 865

The above results, pressure 30kg / cm ² in the void volume (V.V) is Example 1 for Comparative Example 1
5.7%, Example 2 10.6%, and Example 3 11.
It was confirmed that the increase was 6%.

Confirmation of effect of maintaining void volume Pressurized 150 kg / cm ² , while the above test sample was immersed in distilled water at 20 ° C ± 2 ° C,
Repeatedly subjected to compression testing machine at 10H _Z cycle, the thickness after the specified number of times pressed (free) was measured over time, changes in the void volume (free) at this time is shown in the table below.

[Table] Example 1 Example 2 Example 3 Comparative Example 1 Sample basis weight (g / m ² ) 1517 1523 1511 1509 Thickness (mm) before test 3.97 4.00 3.99 3.98 Same V. V (cc / m ² ) 2639 2664 2665 2656 200 thickness after 200 times (mm) 3.15 3.27 3.28 3.06 Same V.V. V (cc / m ² ) 1819 1934 1955 1736 150,000 After 150,000 cycles Thickness (mm) 2.38 2.47 2.49 2.31 Same V. V (cc / m ² ) 1049 1134 1165 986

As a result of the above, the retention ratio of the void volume after the repeated 200 times compression test with respect to the free void volume (V.V) before the test was 68.9 in Example 1.
%, Example 2 was 72.6%, Example 3 was 73.4%, and Comparative Example 1 was 65.4%. Further, the retention rate of the void volume after the repeated compression test of 150,000 times with respect to the free void volume (V.V) before the test was 39.7% in Example 1, 42.6% in Example 2, and Example 3 Was confirmed to be 43.7% and Comparative Example 1 was 37.1%.

That is, Examples 1 to 3 after the repeated compression test
It can be seen that the void volume retention ratio is improved as compared with Comparative Example 1, and the void volume maintenance effect is also excellent.

[0037]

As described above, the papermaking felt according to the present invention is a papermaking felt obtained by needling a fibrous web on one or both sides of a base fabric obtained by laminating a plurality of woven fabrics. Each of the layers of the woven fabric is composed of endless woven fabrics which are joined endlessly in the length direction, and when the woven fabrics are joined at both ends, they are slidably joined in the width direction. In addition, it is characterized in that the longitudinal direction threads are relatively obliquely crossed at the contact surface between the woven fabrics by making the shifting directions relatively different for each layer, and therefore, it is used under pressure. Sometimes it is difficult to crush, the void volume does not decrease, the water squeezing function can be maintained for a long time, and the woven cloth does not mesh at the contact surface between the woven cloth, and an interference pattern (speckle pattern) may occur. And always the flat surface of the felt Maintaining sexual demonstrates an excellent effect of never cause interference marks (spots marked) with respect to the paper.

In the felt for papermaking according to the second aspect of the present invention, the base fabric is composed of two woven fabrics, and the lengthwise yarns of the two woven fabrics are arranged in the machine direction. In addition to the effect of claim 1, it has an excellent effect that the running of the felt is balanced left and right with respect to the machine flow direction.

Furthermore, in the felt for papermaking according to the third aspect of the invention, the base fabric is composed of three woven fabrics, and the lengthwise yarns of one woven fabric of the intermediate layer are arranged in the machine direction. Since the lengthwise yarns of the two woven fabrics of the front and back layers are made to coincide with each other and are diagonally crossed symmetrically with respect to the lengthwise yarns of the woven fabric of the intermediate layer, the effect of claim 1 is obtained. In addition, the strength of the machine in the flow direction is maintained, and the running of the felt balances left and right with respect to the machine flow direction.

Furthermore, the method for producing a felt for papermaking according to the invention of claim 4 is a method for producing a plurality of endless woven fabrics.
In the method for producing a felt for papermaking in which a fiber web is needling on one side or both sides of an endless base fabric that is endlessly joined by abutting both ends in the length direction, when joining both ends of the woven fabric of each layer, It is characterized in that the layers are slidably joined in the width direction and the layers are relatively different in the slidable direction, so that it is possible to easily obtain an oblique effect at the contact surface between the woven fabrics.

[Brief description of drawings]

FIG. 1 is a cross-sectional view schematically showing a felt of the present application.

FIG. 2 is a plan view schematically showing a laminated state of two woven fabrics.

FIG. 3 is an enlarged view of the same side surface.

FIG. 4 is a perspective view schematically showing a state in which two woven cloths are slid in the width direction when both ends are butted and joined.

FIG. 5 is a plan view schematically showing a conventional felt base cloth.

FIG. 6 is a side sectional view of the same.

[Explanation of symbols]

1 Felt 2a, 2b of the present application Woven fabrics 2a ', 2a "Both ends of woven fabric 2b', 2b" Both ends of woven fabric 3 Base fabric 4 Fiber web 5 Contact surface between woven fabrics 6 Oblique W ₁ , W ₂ Longitudinal yarn P Machine flow direction A Ridge-shaped convex portion B Ridge-shaped recess S-S 'Width direction L ₁ , L ₂ Deviation amount θ ₁ , θ ₂ Tilt angle

Continuation of the front page (56) References Table 6-503385 (JP, A) Table 7-506400 (JP, A) International Publication 97/020105 (WO, A1) Albany International Corporation, a product of Albany Co. And New Technology, Journal of Paper and Paper Technology, Japan, Japan Pulp and Paper Technology Association, October 1, 1995, Volume 49, No. 10, 88-96 (58) Fields investigated (Int.Cl. ⁷ , DB name) ) D21F 7/08-7/10

Claims (4)

(57) [Claims] 1. In a felt for papermaking, which is formed by needling a fibrous web on one or both sides of a base fabric in which a plurality of woven fabrics are laminated, each woven fabric of each layer constituting the base fabric is an endless woven fabric. both ends in the length direction of the fabric being formed by joining the endless, upon joining the ends of woven, as well as joined to Shifts in the width direction, relative made different things Shifts to the direction for each layer According to the above, the felt for papermaking is characterized in that the longitudinal threads are relatively crossed at the contact surface between the woven fabrics. 2. The base cloth is composed of two woven cloths.
2. The felt for papermaking according to claim 1, wherein the lengthwise threads of the woven fabric are crossed symmetrically with respect to the machine direction. 3. The base fabric is composed of three woven fabrics, and the length direction threads of one woven fabric of the intermediate layer are made to coincide with the machine direction, and the length direction of two woven fabrics of the front and back layers. 2. The felt for papermaking according to claim 1, wherein the yarn is crossed symmetrically with respect to the lengthwise yarn of the woven fabric of the intermediate layer. 4. The manufacture of papermaking felt needling the fiber web on one or both sides of a plurality of endless base fabric joined laminated endlessly against the both ends in the closed end shaped length direction of the fabric In the method, when the both ends of the woven fabric of each of the layers are joined, they are slid in the width direction and joined, and the slipping direction is relatively different for each layer.