Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21D—TREATMENT OF THE MATERIALS BEFORE PASSING TO THE PAPER-MAKING MACHINE
  • D21D1/00—Methods of beating or refining; Beaters of the Hollander type
  • D21D1/20—Methods of refining
  • D21D1/34—Other mills or refiners
  • D21D1/38—Other mills or refiners with horizontal shaft

Definitions

• the invention relates to a method for fiber treatment according to the preamble of claim 1.
• the effect of the method can be controlled over a wide range by changing the grinding parameters, and in addition to the amount of grinding, a distinction is made in particular as to whether a more cutting or more fibrillating grinding is desired.
• pulp fibers are ground, their drainage resistance generally increases with the amount of grinding.
• a common measure of drainage resistance is the Schopper-Riegler degree of grinding.
• the increase in the degree of grinding has an unfavorable effect on sheet formation on the paper machine, but is accepted because the quality characteristics of the pulp mentioned above play an outstanding role in its usability.
• the grinding parameters are chosen so that the increase in the degree of grinding to achieve the required fiber quality is as small as possible. However, this influence is very limited. In addition, this can make the grinding less economical.
• a grinding method is known from US Pat. No. 4,685,623 which is to use less energy.
• the paper fiber suspension to be ground is guided into narrow wedges ("narrow nips") which form between a rotating central roller and a plurality of rollers that roll on the outside.
• the Page 2
• Wedge nips are very narrow because the central roller is provided with a large number of circumferential grooves or grooves.
• the outside rollers are pressed against the central roller with a defined force, so that the fibers are dewatered and squeezed in the wedge gap.
• Part of the suspension and the water squeezed out in the wedge gaps are carried away transversely to the direction of movement and guided past the actual wedge gap in these grooves in order to be mixed again later with the already ground thickened fibrous material. In this way, problems in the operation of such a machine are to be avoided even with a higher throughput.
• the housing of this apparatus is completely filled with suspension, which is pumped through with an adjustable volume flow.
• the US specification requires that the width of the wedge gaps be smaller than the fiber length.
• the invention is based on the object of providing a method for treating pulp with which it is possible to change pulp or paper fibers in such a way that the strengths of the paper produced therefrom are increased.
• the increase in dewatering resistance that occurs should be as small as possible than in known grinding processes.
• the process is said to be suitable for industrial milling machines.
• the grinding process mainly acts through pressure forces and avoids large relative movements of the grinding tools. As will be explained later, with the aid of such a grinding process, significant fiber-technological advantages can be achieved.
• the pressure forces in the grinding zone can be used to drain the paper fiber.
• this primarily means that the water is either temporarily absorbed by the porous grinding surface and released again later, or that water can flow off into other areas of the grinding apparatus through the porous grinding surface.
• the compressive force is transferred to the fiber less damped and therefore used more for its technological change.
• the fiber is fixed on the grinding surface, i.e. it is prevented from leaving the grinding zone untreated. This effect occurs essentially regardless of the fiber length.
• more fibers can get into the grinding zone because the water that is squeezed out is missing.
• the size of the grinding machine used can be reduced accordingly.
• the fiber attaches itself to a surface with many small unevenness under considerable pressure, which can have a favorable influence on the grinding.
• the grinding surfaces are located on grinding tools which perform a rotational movement in such a way that the liquid absorbed by the pores in the grinding zone is thrown off again after leaving the grinding zone.
• the pores of which are connected not only to the grinding surface but also to other surfaces, the absorption of liquid and the centrifuging off of the liquid can be carried out particularly effectively.
• Particularly suitable materials to create a porous grinding surface for carrying out the process are hard metals, chrome steel, plastics (eg polyethylene, GRP), ceramics or copper alloys. These materials can be sintered. As is well known, can also page 4
• Composites are specifically created open-pore workpieces that are suitable for the use considered here.
• the pore size can be set individually between 5 ⁇ m and 0.5 mm according to the requirements.
• the advantages of the process in terms of grinding technology are as follows: 1. The fiber length is retained much better. 2. The fiber surface is not or significantly less fibrillated. 3. The specific grinding work to achieve the desired strengths is generally less.
• FIG. 1 detailed view of a grinding zone with strip-shaped grinding surfaces to explain the method; 2 shows a variant with cylindrical grinding surfaces; Fig. 3 part of a special grinding device; 4 shows a grinding device with a central grinding cylinder and peripherally arranged grinding rollers; Fig. 5 shows a grinding device in which the porous layer of the grinding cylinder is provided with rear chambers. page 5
• a particularly suitable device for carrying out the method can have a rotating grinding cylinder 3 to which a number of grinding rollers 4 are pressed from the outside.
• the grinding surfaces 1 and 2 are located on them.
• the contact pressure influences the grinding effect and can therefore preferably be adjusted.
• 1 shows a part of such a grinding device, in particular the point at which a grinding zone is created by the interaction of the grinding cylinder 3 and grinding roller 4.
• both the grinding cylinder and the grinding roller are provided with grinding strips 5 and 6, of which only a part is shown. They extend essentially at right angles to the direction of movement of the grinding tools and are evenly distributed over the circumference.
• the grinding strips are dimensioned and arranged so that in the grinding zone the grinding strip 5 of one grinding tool extends into the spaces between the grinding strips 6 of the other grinding tool, as a result of which the volume in between is reduced and in the suspension S therein (indicated by an arrow) ) considerable pressure is built up.
• Both the grinding strips and the cylindrical outer layer of the corresponding grinding tool connected to them are made of porous material. Under certain circumstances, it is sufficient to produce only the grinding strips from porous material and to fix them on the grinding cylinder or on the grinding roller.
• the water of the fiber suspension which is under increased pressure in the grinding zone, can penetrate into the pores of the grinding surface, thereby thickening the fiber itself.
• the volume between the grinding tools increases again, and the water W (indicated by an arrow) can emerge from the pores again.
• This effect is strongly supported by the fact that both grinding surfaces rotate, so that a centrifugal force acting perpendicular to the grinding surface is generated. Since the grinding strips form a toothing, the relative speed of the two grinding tools to one another is low within the grinding zone, as a result of which shear movements and shear forces acting on the fibers are largely avoided.
• the toothing also has an impact in terms of grinding technology, which is due to the fact that the compressive forces acting on the fibers occur in a pulsating manner, which is desirable in many cases in terms of grinding technology.
• FIG. 2 Another application is shown in FIG. 2 with cylindrical grinding surfaces, that is to say those which are not provided with strips and which, in order to carry out the method, roll against one another with little or no slip. It can be seen in this illustration that the Mahi cylinder 1 'is provided with a porous layer 8 ' and page 6
• the grinding rollers 4 ' with a porous material layer 7'.
• the grinding strips can have the shape of involute teeth, which optimizes the rolling conditions in the grinding zone, but is somewhat more complex to manufacture than e.g. the grinding strips shown in Fig. 1.
• the grinding rollers 4 rotate here in a fixed backdrop 11.
• the mahizylinder 3 has annular circumferential shoulders 12 on the axial end faces, which axially seal the volume formed between the grinding strips 5, 6 in the grinding zone.
• the grinding device shown in FIG. 4 for carrying out the method is only shown schematically.
• the suspension S is added through an inlet 14. This can be done via a wide gap or via a headbox, similar to that used in paper machines.
• the addition point is located next to the material drain 13 and is separated from it by a guide plate 15. In this way, forced delivery over almost 360 ° over the entire circumferential course of the housing 16 is ensured.
• the suspension flow through this grinding device is defined and can be adjusted easily and safely.
• the housing is preferably not completely included Page 7
• a suspension level can form at the material drain 13.
• the housing 10 can - as drawn here - be cylindrical on the inside or, according to FIG. 3, be provided with a link 11 in which the grinding rollers rotate with a small gap distance.
• a chamber on the back of the porous layer that is to say the side of the layer opposite the grinding surface. If necessary, this can be fed with pressurized water.
• the water may be mixed with suitable cleaning chemicals.
• 5 shows a simple possibility of realizing such a chamber 17 using the example of a grinding cylinder 3 ′′, which is peripherally surrounded by grinding rollers 4 ' .
• the chambers 17 are formed by the fact that between the continuously porous material layer 8' and the cylinder body of the Mahi cylinder 3 "spacer strips 18 are attached, between which the volumes of the chambers 17 remain free.
• the rinse water is added through lines 19.
• the chamber 17 shown in FIG. 5 and the lines 19 connected to it can be used to discharge water which has penetrated through the pores of the material layer 8 ' .
• a chronological sequence of drainage and - if necessary - flushing is also conceivable.

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• Paper (AREA)
• Polishing Bodies And Polishing Tools (AREA)

Applications Claiming Priority (2)

Publications (2)

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• 2004
  • 2004-11-11 BR BRPI0417436-4A patent/BRPI0417436A/pt not_active IP Right Cessation
  • 2004-11-11 EP EP04820585A patent/EP1702104B1/fr not_active Not-in-force
  • 2004-11-11 WO PCT/EP2004/012762 patent/WO2005061783A1/fr active IP Right Grant
  • 2004-11-11 PT PT04820585T patent/PT1702104E/pt unknown
  • 2004-11-11 AT AT04820585T patent/ATE381637T1/de not_active IP Right Cessation
  • 2004-11-11 DE DE502004005776T patent/DE502004005776D1/de not_active Expired - Fee Related
  • 2004-11-11 US US10/596,360 patent/US20070090209A1/en not_active Abandoned

Non-Patent Citations (1)

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