JP2800908B2 - Calendar processing method for paper sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for improving the surface condition such as smoothness and gloss of paper after being dried by a dryer.

[0002]

2. Description of the Related Art Generally, in a paper mill, a calendar device is used as a device for performing surface treatment after drying paper made with a dryer. Typical examples are a chilled nip calendar, a soft nip calendar, and a super calendar. Of these, the chilled nip calendar,
The soft nip calender is a device that is attached after the dryer of the paper machine to modify the surface properties of the paper sheet online. A chilled nip calendar is one in which a pair of or more nips are made of metal chill rolls.
The soft nip calender is composed of a chill roll made of metal and a resin roll having an elastic Shore D hardness of about 90 degrees, and has only one pair of nips formed on the peripheral surface of the resin roll. In addition, the super calendar is one in which cotton rolls and chilled rolls having an elastic Shore D hardness of about 80 degrees are alternately arranged in a vertical direction, and the paper sheet is wound off-line by high-pressure multi-nip processing, It is used in the production of highly smooth paper, such as gravure printing paper.

[0003]

The paper sheets processed by the various types of calenders described above have distinct differences between the chilled nip calender, the soft nip calender, and the super calender. Although the thickness of the paper sheet immediately after being dried in the paper machine is not uniform, the paper sheet is processed through the nip of the calendar device, and how the surface state changes is examined. Considering the cross section perpendicular to the flow of the paper sheet, the following can be said.

[0004] First, in a chilled nip calendar in which a nip is formed by a metal chill roll, a convex portion on the surface of a paper sheet is pressed and flattened. I can't do it,
The thickness of the paper sheet is uniform but the density is not uniform.

Next, in a soft nip calender in which a nip is composed of an elastic roll and a metal chill roll, when a paper sheet having an uneven thickness immediately after being dried by a paper machine passes through the nip, the metal chill roll surface is formed. Is deformed flat by the smooth surface of the roll. However, when the chilled roll side is processed flat, the paper sheet surface of the elastic roll side, which hits the back side of the paper sheet,
Complex irregularities appear due to the irregularities on the chill roll side in addition to the original irregularities. However, since the elastic roll can be deformed by the elasticity in a form corresponding to the unevenness, the concave portion on the paper surface can be subjected to the pressure treatment. Then, the paper sheet has a non-uniform thickness but a uniform density, and the surface smoothness of the roll is transferred to the surface of the paper sheet on the chill roll side to impart smoothness and gloss.

[0006] In terms of printability and surface appearance of paper, a soft nip calendered product having a uniform density is superior to a chilled nip calendered product having a uniform ink absorption and fixing and nonuniform density. I have.

[0007] The super calender is one in which cotton rolls and chilled rolls are alternately arranged in the vertical direction and subjected to a high-pressure multi-nip process, and is suitable for producing highly smooth paper such as gravure printing paper. . However, in the super calendar, the nip is formed by the contact of the chill rolls on the upper and lower sides of the cotton roll, so that the cotton roll receives a linear pressure of 2 degrees per rotation of the cotton roll.
Cotton rolls with a hardness of 75 to 85 degrees are low in elastic deformation at locations where they are subjected to linear pressure, and repeated linear pressures in a short time cannot return to the original shape from thermal stress hysteresis, causing troubles such as breakage. Is easy to occur. For this reason, the super calendar is installed off-line at a speed lower than the speed of the paper machine for making the base paper.

The elastic roll used for the soft nip calender has a heat-resistant synthetic resin layer provided on the surface of a metal roll.
mm, the Shore D hardness is 85-95 degrees, which is higher than that of the cotton roll to reduce the amount of elastic deformation, and furthermore, elastic deformation as a structure that forms only one chilled roll and nip on the circumference of the resin roll It takes time to restore the original shape later and extends the life of the elastic roll resin layer so that it can be operated online.

However, the soft nip calendered product is
Although it has better surface properties than the chilled nip calendered product, the number of times of nip treatment is small and the hardness of the resin roll is higher than that of the cotton roll, so it is far from the surface of the paper sheet of the super calendered product.

[0010] Recently, in order to further improve the paper surface properties, a high-temperature soft nip calendering treatment in which the temperature of the chill roll is set to about 150 ° C has been proposed, and the life of the elastic roll is further shortened. . Development of heat-resistant resin is also progressing, but basically, when heat resistance is increased,
At present, the hardness of the resin layer tends to be high, which is contrary to the processing characteristics of the paper surface.

In view of the above-mentioned problems of the prior art, the present invention can provide a paper sheet with the same smoothness and gloss as a super calendar, and has excellent suitability for high-speed processing. It is an object of the present invention to provide an apparatus and method for treating the surface of a paper sheet, which is capable of solving the problem that the service life is short as seen in the elastic roll.

[0012]

According to a first aspect of the present invention, there is provided a paper sheet surface treating apparatus which covers a cylindrical fixed beam and an outer peripheral surface of the fixed beam except for a gap formed by a guide member and is made of an elastic synthetic resin. A rotatable tubular sleeve having an outer layer, a metal roll having a smooth surface that is rotated in contact with the tubular sleeve in opposition, and at an opposing contact position between the metal roll and the sleeve, with respect to the inner surface side of the sleeve. And a pressure treatment shoe having a concave curved surface for pressing while sliding. Further, the surface treatment apparatus according to the second invention of the present application provides a space between the fixed beam and the sleeve for cooling the sleeve. The surface treatment device according to the third invention of the present application is characterized in that a temperature-controlled lubricating oil is supplied, and the outer layer made of an elastic synthetic resin of the sleeve has a Shore D
The surface treatment apparatus according to the fourth aspect of the present invention is characterized in that the outer surface of the sleeve made of an elastic synthetic resin has a surface roughness (Rmax) of 20 microns or less as defined by JIS B0601. In the surface treatment apparatus according to the fifth aspect of the present invention, the concave surface of the pressure shoe is concentric with the outer peripheral surface of the metal roll and forms an arc having a slightly longer diameter.

Further, the surface treatment method for a paper sheet according to the sixth invention of the present application is characterized in that the outer peripheral surface of the cylindrical fixed beam is covered with a gap formed by a guide member, and a tubular sleeve made of an elastic synthetic resin outer layer is provided. A metal sheet having a central angle of 10 to 20 degrees in a metal roll in a state in which the sleeve is pressed in a concave curved shape from the fixed beam side to the opposed pressure-contacted portion with a metal roll having a smooth surface. An area is formed, and a paper sheet having a moisture content of 10% or less is passed through the area to smooth and gloss the surface of the paper sheet. In the paper sheet surface treatment area,
Linear pressure when passing through paper sheet is 60-500KN /
m.

The cylindrical fixed beam in the present invention is for maintaining the tubular sleeve in a cylindrical shape, and a gap is provided between the fixed beam and the sleeve by a guide member attached to the fixed beam. .
As a desirable mode, lubricating oil adjusted to a low temperature is supplied to the gap between the fixed beam and the sleeve, and a film-like oil film is formed on the inner surface of the sleeve. Further, it is preferable that a plurality of guide members are provided in a rail shape in parallel with the outer peripheral surface of the fixed beam at equal intervals, but a gap between the fixed beam and the sleeve can be formed, and the inner surface of the sleeve can be formed. The configuration is not limited to the above configuration as long as smooth sliding is possible.

The material of the elastic synthetic resin layer of the sleeve is preferably a synthetic resin composed of at least one of epoxy resin, polyamide resin, polyimide resin, polyimide amide resin and polyurethane resin.
The side in contact with the paper sheet preferably has a Shore D hardness of 40 to 70 degrees, and more preferably 50 to 60 degrees. If the Shore D hardness is less than 40 degrees, plastic deformation occurs in the pressure shoe portion, shortening the service life, and at the same time, high smoothness and gloss cannot be obtained. If it exceeds 70 degrees, the curvature cannot be obtained, and it is difficult to form a cylindrical shape along the guide member. Also,
The surface roughness is defined as Rma specified in JIS B 0601.
x20 microns or less, and the smaller the better, the more preferable it is 2-5 microns in consideration of processing accuracy.
If it exceeds 20 microns, it is a phenomenon that the gloss becomes uneven due to the uneven density of the treated paper sheet surface.
So-called mottling is likely to occur.

In the present invention, a pressure shoe having a concave curved surface for pressing the sleeve from the inner surface is provided, and the tubular sleeve is pressed against the metal roll to create a paper sheet surface treatment area. To press the pressure shoe, a hydraulic device that can easily adjust the pressure is suitable for use.However, in order to prevent the surface temperature of the pressure shoe from abnormally increasing the oil temperature of the hydraulic device, It is desirable to line the surface of the pressure shoe with a heat insulating material. Further, the linear pressure at the time of processing the paper sheet is preferably 60 to 500 KN / m. 60K
If it is less than N / m, the surface treatment is incomplete and only low smoothness and gloss can be obtained. If it exceeds 500 KN / m, the paper thickness of the paper sheet tends to be too small, resulting in insufficient strength. Also, the concave curved surface at the tip of the pressure shoe is concentric with the outer peripheral surface of the metal roll, and is formed by a slightly longer arc.
It is preferable to adjust so that a uniform pressure is applied to the surface treatment area of the paper sheet having a central angle of 10 to 20 degrees in the metal roll. If the central angle is less than 10 degrees, smoothness and gloss may be insufficient, and if it is 20 degrees or more, the strength of the paper sheet may be insufficient.

The paper sheet to be processed in the present invention is a paper sheet after the paper has a moisture content of 10% or less. If paper having a high moisture content in paper, such as wet paper, is treated by the apparatus according to the present invention, the paper may be broken due to insufficient strength as a problem before surface treatment.

[0018]

According to the present invention, in a surface treatment apparatus having the above-mentioned structure, when a paper sheet is passed through a contact surface between a metal sleeve and a tubular sleeve deformed into a concave curved surface by a pressure shoe, The smoothness of the surface of the roll is transferred to the surface of the paper sheet which is in contact with the surface of the paper, so that the unevenness of the surface is smoothed and flattened. The irregularities on the metal roll side appear on the tubular sleeve side, but on the tubular sleeve side, the sleeve surface can be deformed along the irregularities on the paper sheet surface. As a result, without increasing the density by compressing the convex portion of the paper sheet, a smooth and glossy paper sheet surface is obtained on the metal roll side, and the paper sheet is processed along the surface irregularities on the sleeve side. The resulting paper sheet surface is obtained. Since the density of this paper sheet is uniform, the absorption and fixing of the ink become uniform. In addition, since the tubular sleeve is provided with a gap between the fixed beam and the sleeve, frictional heat generated when the paper sheet is passed and heat derived from the heat source provided inside the metal roll are easily generated. Since heat is dissipated, high-speed operation is possible and the life of the tubular sleeve is long.

Further, by supplying the cooled lubricating oil to the gap between the fixed beam and the tubular sleeve, the heat radiation action is further promoted. By setting the Shore D hardness of the elastic synthetic resin layer of the tubular sleeve to 40 to 70 degrees, the tubular sleeve responds to minute irregularities on the surface of the paper sheet on the tubular sleeve side, and the surface of the paper sheet on the metal roll side Smoothing is achieved. Further, by adjusting the surface roughness of the elastic synthetic resin layer of the sleeve to a surface roughness (Rmax) of 20 microns or less as specified in JIS B 0601, the smoothness and gloss caused by the surface roughness of the sleeve are prevented. To prevent. The concave curved surface of the pressure shoe is concentric with the outer peripheral surface of the metal roll and has a slightly longer diameter, so that the distance between the metal roll and the elastic synthetic resin layer of the tubular sleeve is constant over the entire surface treatment area of the paper sheet. Can be kept. Further, the linear pressure during the paper sheet passing process is 60 to 500 KN / m.
By doing so, a desired smoothness and gloss can be obtained, and a paper sheet having a surface property equivalent to that of a conventional super calendar can be obtained.

[0020]

1 is a horizontal sectional view showing an embodiment of a calendar device according to the present invention, and FIG. 2 is a vertical sectional view of the lower half of the main body of the same calendar device.

In FIGS. 1 and 2, the calendar device according to the present invention comprises an upper half and a lower half. The lower half has a fixed cylindrical beam (1) fixedly attached to a support leg (11) for installation, and further has an outer circumference of the fixed beam (1) parallel to the central axis of the cylinder. Guide bars (8) are provided at appropriate intervals. A tubular sleeve (2) provided so as to cover the cylindrical fixed beam (1) can be rotated with a gap between itself and the peripheral surface of the fixed beam (1) by the guide bar (8). And both ends are supported by a clamp desk (9) to keep the gap airtight. Inside the fixed beam (1), there is provided a pressurizing chamber (13) which slidably incorporates a pressurizing shoe (3) having a concave curved surface at the tip.
3) is connected to a hydraulic device (not shown) via a pressurized oil supply path (4), and the internal pressure of the pressurized chamber (13) is controlled. Since the pressure shoe (3) is in contact with the sleeve (2) under pressure, when the internal pressure of the pressure chamber (13) increases,
The pressure shoe (3) presses the inner surface of the sleeve (2),
A paper sheet surface treatment area is formed between the metal sheet and the metal roll (10).

On the other hand, a rotatable metal roll (10) is provided in the upper half of the calendar device, and the outer peripheral surface of the metal roll (10) holds a running paper sheet (15) therebetween. And is in opposing pressure contact with the lower half sleeve (2). A pressure shoe (3) is located at a pressure contact portion between the metal roll (10) and the sleeve (2).
As the metal roll (10) rotates, the sleeve (2) also rotates around the fixed beam (1), but when the sleeve (2) comes into pressure contact with the metal roll (10), the metal roll (10) is rotated. ) Is deformed into a concave curved surface along the outer surface shape and the tip shape of the pressure shoe (3). The sleeve (2) is formed by impregnating and applying a urethane elastic resin on the front and back surfaces of a thick base cloth as a core layer in order to maintain a tube shape. Shore D hardness of the outer elastic resin layer is 40 to 70
Degrees, preferably 50 to 60 degrees, and the base fabric has a thickness of 1.5
の も の 4.0 mm, preferably about 2.0 to 3.0 mm. As the urethane resin to be impregnated on the front and back surfaces of the base fabric, a diamine-cured urethane resin is preferable, and 2.0 to 3.0 mm for the front side and 0.5 to 1.0 mm for the back side. The surface roughness of the front side resin layer on the side in contact with the paper sheet to be treated is Rmax 20 microns or less, and the surface roughness of the back side resin layer is Rmax 40 to 80 microns. The overall thickness of the sleeve (2) is 5.0 to 7.0.
It is about 0 mm.

The surface roughness of the metal roll (10) is preferably as smooth as possible, but may be Rmax 0.5 to 2.0 microns.

The calendar device according to the present invention is driven by rotating a metal roll (10) using a driving device (not shown), and a sleeve is pressed against the metal roll (10) with a paper sheet (15) interposed therebetween. (2) is rotated by transmitting the rotation of the metal roll (10).

The metal roll (10) and the sleeve (2)
Pressure contact surface between the contact width is 100-400 mm,
Preferably, it is formed as wide as 150 to 200 mm. The dried paper sheet is subjected to a surface treatment when passing through the pressure contact surface formed on the concave curved surface. The linear pressure during the treatment is 60 to 500 KN / m.

When the calendar device of the present invention is driven, the pressure contact surface between the pressure shoe (3) and the metal roll (10)
The heat of a heating device built in the metal roll (10) and the sleeve (2) and the pressure shoe (2) when the rotating metal roll (10) rotates the sleeve (2) through the paper sheet (15). The heat generated at the pressure contact surface with 3) and the internal heat generated by the deformation of the sleeve (2) itself at the pressure contact surface gradually increase the temperature of the sleeve (2). This heat is
Heat is effectively dissipated by the gap between the sleeve (2) and the fixed beam (1), or a contact environment with cold air, cooling liquid, or the like is created for the sleeve (2) at a place other than the paper sheet surface treatment area. This makes it possible to suppress abnormal temperature rise and maintain the temperature within a certain temperature range.

As a more preferable method for controlling the temperature of the sleeve (2), a supply path (5) of a cooled lubricating oil is provided inside the fixed beam (1), and the temperature is always controlled to a constant cooling temperature range. Lubricating oil is supplied to the inner surface of the sleeve (2). The lubricating oil forms a film-like oil film on its inner surface by centrifugal force caused by the rotation of the sleeve (2),
The friction at the contact surface with the guide bar (8) and the pressure shoe (3) is reduced to facilitate rotation. As described above, most or a part of the lubricating oil that has functioned as the cooling of the sleeve (2) and as the lubricating oil is discharged from the lubricating oil recovery path (6) immediately before the paper sheet surface treatment area. If the temperature of the lubricating oil is equal to or higher than the predetermined temperature, the lubricating oil is cooled again by the heat exchanger, and then a closed system is supplied again from the supply path (5). The lubricating oil discharge path (7) is
Used for discharge at rest or when changing lubricant.

Generally, when passing through the paper sheet surface treatment area, the lubricating oil film shows a temperature rise of about 15 to 20 ° C. Therefore, the temperature of the lubricating oil recovery path (6) is set to 50 ° C.
The cooling temperature at the time of supply is set so as to be before and after, and the surface temperature of the sleeve (2) is kept constant.

FIG. 3 shows two sets of calendar units having the same configuration as that of FIG. In this way, the paper sheet (15) is processed on both front and back sides while being guided by the guide roll (20).

[0030]

According to the present invention, the smoothness and gloss of the paper surface are further improved as compared with those using the chilled nip calendar and the soft nip calendar, and the quality can be equal to or very close to that using the super calendar. It became.

Further, since the density is low and constant, it is possible to produce a printing paper which is bulky and has excellent printability.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a surface treatment apparatus according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of a lower half of the apparatus.

FIG. 3 is a cross-sectional view of a surface treatment apparatus according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylindrical fixed beam 2 Tubular sleeve 3 Pressurizing shoe 4 Pressurized oil supply path 5 Lubricating oil supply path 6 Lubricating oil recovery path 7 Lubricating oil discharge path 8 Guide bar 9 Clamp desk 10 Metal roll 15 Paper sheet

Claims (7)

(57) [Claims] 1. A method for calendaring a paper sheet, comprising:
A cylindrical sleeve having an outer layer made of an elastic synthetic resin rotatable around the outer periphery of the cylindrical fixed beam while leaving an interval by the guide member, and a metal roller having a smooth surface that is driven to rotate are brought into opposing contact with each other. In a state in which the sleeve is pressed against the metal roll from the inner surface side by a pressure shoe having a curved surface, a paper sheet having a water content of 3 to 10% is continuously passed and pressed to the opposed contact position. Calendar processing method for paper sheet. 2. The paper sheet according to claim 1, wherein the paper sheet is continuously passed and pressed while supplying lubricating oil whose temperature has been adjusted for cooling the sleeve to the space between the fixed beam and the sleeve. Paper sheet calendar processing method. 3. The method for calendering a paper sheet according to claim 1, wherein the outer layer made of an elastic synthetic resin of the sleeve has a Shore D hardness of 40 to 70 degrees. 4. The outer layer made of an elastic synthetic resin of the sleeve has a surface roughness (Rma) defined by JIS B0601.
x) less than 20 microns.
4. The method for calendaring a paper sheet according to any one of claims 1 to 3. 5. The paper sheet calendering method according to claim 1, wherein the concave curved surface of the pressure shoe forms an arc of a slightly longer diameter concentric with the outer peripheral surface of the metal roll. 6. The position at which the tubular sleeve and the metal roll are in opposition to each other is a central angle 1 in the metal roll.
The angle is in a range of 0 to 20 degrees.
3. A calendar processing method for a paper sheet described in the above. 7. The method according to claim 6, wherein the pressure when the paper sheet is continuously passed and pressed is 200 to 500 N / cm ² .