CN1697902A - Method for the treatment of fiber material - Google Patents

Abstract

Disclosed is a method for modifying suspended paper fibers or pulp fibers, especially in order to increase the rigidity of the paper that is made from said fibers. According to the inventive method, two grinding areas (1, 2) are pressed against each other and moved such that the relative speed between the grinding areas (1, 2) and the fiber material (F) in the grinding zone (3) is as low as possible. Said method can be carried out in a particularly favorable manner by means of grinding elements (9) which support one (1) of the grinding areas and are rolled off on the inside of a grinding drum (8) that supports the grinding area (2).

Description

A method of processing pulp

technical field

The invention relates to a method of treating pulp according to the preamble of claim 1 .

Background technique

The method of processing pulp of the type mentioned above is also commonly referred to as the refining process. It has been known for a long time that pulp fibers must be refined so that the paper produced from them later has the required properties, especially strength, structure and surface properties. The vast majority of commonly used refining processes utilize a refining surface provided by rails, commonly referred to as blades. The corresponding machines are mostly called blade refiners. In special cases, the refining process is also used in the case where at least one refining surface is bladeless, so that the refining process can be transmitted by friction or shear force.

By changing the refining parameters, the effect of processing can be controlled within a wide range. In addition to the amount of extraction, especially depending on whether refining is required, different processing effects with stronger cutting or stronger degree of fibrillation will be formed. If the pulp fibers are treated by known refining processes, the dewatering resistance of the pulp fibers will increase with increased extraction. A customary measure of resistance to dehydration is freedom according to the Schopper-Riegler method.

Increased freeness has a detrimental effect on the structure of the paper machine, but is acceptable because the aforementioned pulp quality characteristics are particularly important for its performance. In most cases refining parameters are chosen so that the increase in freeness to achieve the required pulp quality is as low as possible. However, the possibility of such effects is very limited. Additionally, refining processes may become less favorable from a force-economic point of view.

Contents of the invention

The main object of the present invention is to provide a pulp treatment method with which pulp fibers or paper fibers can be modified such that the strength of the paper produced therefrom is increased. The increase in dehydration resistance that accompanies this process is at least less than with existing refining processes.

The object of the present invention is achieved by the technical features described in claim 1.

Taking full advantage of the new refining process makes it possible to avoid refining shear loading of the pulp fibers to the greatest extent. Therefore, compared with the existing refining process, the present invention can mainly realize the following three important advantages:

1. The fiber length is basically better maintained.

2. There is no or very little fibrillation on the fiber surface.

3. A general reduction in special refining work to obtain the desired strength.

Comparative tests on long fiber pulp have shown that blade refining produces a freeness of 45°SR in order to achieve a tear length of 8Km, whereas the new treatment produces only a freeness of 18°SR. Required special refining work reduced to under 50%.

It is conceivable to alter the surface of the fiber by means of a new refining process to improve flexibility and cohesion without having to remove the fibril from the outer surface of the fiber. The production of fines, ie fiber components, can also be neglected.

Advantages 1 and 2 play a special role if this treatment is used for recycled fibers. Recycled fibers have been refined through at least one, if not multiple refining processes, which naturally avoids any further crushing.

Description of drawings

The invention and its advantages will be explained below with reference to the accompanying drawings. Attached are:

Fig. 1 is a simple example of carrying out the method according to the invention;

Fig. 2 is the device schematic diagram of carrying out the method of the present invention;

Figure 3 is the deformation of the rolling structure (roll structure);

Fig. 4 is the schematic diagram that another device that carries out the method of the present invention is in use position;

Figure 5 is a qualitative intensity graph.

Detailed ways

Figure 1 shows a partial view of an apparatus particularly suitable for carrying out the method of the invention. However, no technical design details are shown. According to the illustration, the refining surface 1 is located on the outer circumference of the rotating refining body 9 . The refining surface 2, as the inside of a similar rotating refining drum 8, conveys the pulp F to be refined, which is a watery suspension containing paper fibers or pulp fibers inside the rotating refining drum 8. The pulp F is evenly distributed on the refining surface 2 and rotates thereon due to centrifugal force. The peripheral speed of the refining body 9 is indicated by the direction arrow 6 and the peripheral speed of the refining drum 8 is indicated by the direction arrow 7 . According to the invention, the movement of these two refining surfaces is such that at the point 5 where the two refining surfaces are closest, a very low velocity is produced in the main direction of motion of the refining surfaces, between the pulp F and the refining surfaces. The main direction of motion results from the motion of the refining surface caused by the drive. During this process, the refining main body 9 rolls the inner side of the refining drum 8 . The axis of rotation of the refining body 9 is parallel to the axis of rotation of the refining drum 8 and may be spatially fixed. The actual refining zone 3 starts at the point where the refining surface 1 is immersed in the layer of pulp F. The refining body 9 is pressed against the refining surface 2 with a force P in order to generate the compressive force. The refining effect can be adjusted by changing this force. A line force of 2 to 10 N/mm has proven to be advantageous. The force in this range of values is related to the width of the contacting refining body, regardless of the expansion of the contacting surface in the direction of motion. Thus, fiber processing follows a compression and crushing process which plies the fibers in a very gradual manner. No real shearing and cutting forces are transmitted to the fibers.

Here the refining surface 1 has grooves 4 whose effect cannot be compared with the blades of existing blade refiners in which the blades move relative to each other at a higher speed. The grooves 4 co-operate with opposing surfaces, eg for absorbing moisture of the fibres, to generate pressure pulses. They also pass the pulp F through the refining zone 3 . The grooves may extend along the entire axial length of the refining body, but may also be interrupted. Depth t and width u should normally be at least 2 mm. Offsets of right-angle configurations are also possible. For example, the ladder structure shown in Fig. 3 is taken as a reference example.

The apparatus for carrying out the method of the invention is generally manufactured in the position of use as shown in FIG. 2 . The horizontally arranged refining drum 8 is rotated by the action of a drive 11 . A plurality of refining bodies 9 are located inside the refining drum and move as previously described such that a rolling motion occurs at the point of contact with the refining drum 8 . The refining body 9 is rotated by the drive 10 , the axis of rotation of which is vertical and spatially fixed. The fed pulp F is gradually refined with this device, and the discharged pulp F' can be removed after the refining process. If such a plant operates continuously, continuous pulp throughput measurement must be carried out for uniform refining.

Another possible way of carrying out the method of the invention is shown in Figure 4, where the centerlines of the refining drum 8 and the refining body 9 are horizontal. This arrangement allows for continuous refining but requires passage through the refining area to accomplish the desired extraction. A thick layer of pulp F to be refined is injected into the stationary refining drum 8 and flows down the inner wall of the refining drum by gravity. Since the rotational movement of the refining body 9 around its axis (direction of the arrow 6) and the rotational movement of the refining body 9 around the center line of the refining drum 8 (direction of the arrow 6') are overlapping, the refining body 9 rolls over the refining drum 8 inner wall. Typically, such a device comprises a plurality of refining bodies 9 supported on a rotating frame. By selecting the addition and removal stations of pulp F, the pulp flow rate can be adjusted. The refining body can run in the opposite direction (as drawn here) or in the same direction as the flow of pulp.

Figure 5 schematically shows the improvements that can be achieved with the new processing method. The figure shows the freeness (arrow 12) plotted along the tear length (arrow 13). Curve 14 shows the result of the conventional blade refining method and curve 15 shows the result achieved by the new method. It can be easily seen that lower freeness can be produced according to the method of the present invention to achieve the desired high tear length. The graph is only used to show basic trends.

Claims (14)

1, a kind of paper fiber in the water sample suspension or method of paper pulp fiber of changing, wherein paper pulp (F) imports and is positioned at refining surface (1 by at least one, 2) the refining zone (3) between, refining surface (1,2) motion and mutual extrusion relative to each other make the intensity of paper of manufacturing change thereby mechanical refining work is delivered to paper pulp;

It is characterized in that,

Relative velocity between paper pulp (F) and the refining surface on refining surface motion principal direction, be at most refining surface (1,2) in refining zone (3) place, immediate position (5) the refining surface of fast driving absolute velocity 10%, making does not have shearing force or low-down at the most shear transfer to the fiber in refining zone (3).

2, method according to claim 1, it is characterized in that, relative velocity between described paper pulp (F) and the refining surface on refining surface motion principal direction, be lower than refining surface (1,2) in refining zone (3) place, immediate position (5) the refining surface of fast driving absolute velocity 5%.

3, method according to claim 1 and 2 is characterized in that, the relative motion of described refining surface (1,2) is the roll off motion.

According to claim 1,2 or 3 described methods, it is characterized in that 4, refining is transmitted described mechanical refining work by compression paper pulp.

According to claim 1,2,3 or 4 described methods, it is characterized in that 5, refining surface (1) has groove (4,4 '), the horizontal expansion on the motion principal direction of the refining surface of motion of this groove.

6, method according to claim 5 is characterized in that, the degree of depth of described groove (4,4 ") is at least 2mm, and the width (u) on the direction of motion of the refining surface of motion is at least 2mm.

According to claim 5 or 6 described methods, it is characterized in that 7, described second refining surface (2) does not have the groove of horizontal expansion.

8, according to the described method of each claim of front, it is characterized in that, a refining surface (1) is positioned at the outside of columniform refining main body (9), and the center line of this refining main body (9) is with respect to refining cylinder (8) motion that comprises another refining surface (2) in the inboard.

9, method according to claim 8 is characterized in that, a plurality of refining main bodys (9) are applied in the refining cylinder (8).

According to the described method of each claim of front, it is characterized in that 10, paper pulp (F) is not with respect to a motion in the refining surface (1,2) in refining zone (3).

According to the described method of each claim of front, it is characterized in that 11, described fiber is presented in the suspension with 10% solids content at the most.

12, method according to claim 11 is characterized in that, solids content equals 6% at the most.

According to the described method of each claim of front, it is characterized in that 13, the absolute velocity of at least one refining surface (1,2) remains the numerical value of 8～30m/sec.

According to the described method of each claim of front, it is characterized in that 14, refining surface (1,2) is extruding mutually, make that producing size in refining zone (3) is the straight line force of 2～10N/mm.

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