EP1956141B1 - Roll cover with friction-reducing filler - Google Patents

Abstract

The roller (1) has a roll cover (4) covering a generated surface of a cylindrical roller base (3), and comprising a top layer (7). The top layer lies outside, and is made from a material mixture (8) with a polymer material. A filler material (9) is sectionally embedded into the polymer material and formed from fluorine containing material e.g. polytetrafluoroethylene, polyvinylidene fluoride and fluorinated ethylene propylene. The filler material has a higher abrasion resistance and a smaller detention and sliding friction coefficient than the material mixing.

Description

The invention relates to a roller according to the preamble of patent claim 1.

Such a roller is out of the WO-A-94/09208 known.

Rollers are used in many places on a web-processing machine. About such rolls either the material web is guided directly or it is the material web guided on a belt which supports the web. Furthermore, the surface of the wear layer of the roll cover of the roll is often cleaned by means of a fixed or oscillating scraper, which is in tribological contact with it.

In addition, scrapers are used, for example, when painting paper. Here, a scraper acting as a squeegee is in contact with the roll cover either on the entire roll length (e.g., film press), or else the dosing member contacts the roll cover only in the edge zones of the roll cover (e.g., a counter roll coater).

Due to the mentioned conditions of use, roller covers are subject to heavy wear, which manifests itself either uniformly over the entire surface of the roller cover or only in certain zones of the surface of the roller cover.

From the US6,328,681 the use of UHMW-PE particles is known, which are embedded as a particulate filler in the polymeric matrix material of the wear layer. The UHMW-PE particles have an increased abrasion resistance compared to the polymeric matrix material in which they are embedded. This is intended to improve the service life of the rolls.

In particular, in applications with high wear and high wear areas subject to the roll cover, the use of such UHMW-PE particles proves to be insufficient.

It is the object of the present invention to propose a roll with a roll cover with a wear layer, which is inexpensive to produce despite improved compared to the prior art life.

The invention is achieved by a roller for a machine for processing a material web, in particular a paper, board or tissue machine, with a cylindrical roller core and with a roller cover covering the lateral surface of the roller core. The roll shell of the roll according to the invention further comprises an outer wear layer of a material mixture with polymer material, i. from a material mixture comprising polymeric material. In the material mixture, a filler is embedded at least in sections, which has a higher abrasion resistance than the material mixture. According to the invention, the filler also has a lower coefficient of adhesion and sliding friction than the material mixture.

The wear layer, viewed in its length, has two edge regions bounding the wear layer in its length and a center region arranged between the edge regions, and the filler is embedded in the material mixture only in the two edge sections.

As a result, a cost-effectively produced roll is provided with a roll cover with a wear layer, which is composed of a material mixture with polymer material in which a filler is embedded, which has a higher abrasion resistance and a lower coefficient of adhesion and sliding friction than the material mixture.

Due to the inventive design of the roll cover wear this means less than the known from the prior art roll covers, since the wear layer on the one hand has a higher abrasion resistance and secondly due to the lower friction values less friction between the wear layer and one with the wear layer in tribological Contact located component arises. Due to the lower friction, the heating of the tribologically stressed roller lining is further reduced, whereby the material fatigue of the roll cover is significantly slowed down.

The use of the filler according to the invention, which has both a higher abrasion resistance and a lower coefficient of adhesion and sliding friction than the material mixture in which it is embedded, has over a roll cover in which a first filler with higher abrasion resistance and a second filler with a lower adhesive and sliding friction coefficients embedded in the material mixture has the advantage that in the roll cover according to the invention the friction-reducing filler is not removed due to its increased abrasion resistance, whereas in the roll cover with two fillers, the first filler due to its higher frictional resistance and the second filler due to its lower abrasion resistance stronger than that Filler of the invention is removed.

Abrasion resistance in the sense of the present invention should be understood to mean the abrasion resistance, as determined according to DIN standard 53516.

Advantageous embodiments of the invention are specified in the subclaims.

A particularly advantageous embodiment of the invention provides that the filler is particulate. Particles generally have isotropic properties, which is why particles can be easily and inexpensively mixed with the material mixture to provide a specific property, without having to pay attention to their orientation in the mixture.

A variety of fluorine-containing polymeric materials combine the properties of a high abrasion resistance coupled with low coefficient of adhesion and sliding friction. Therefore, it proves to be particularly advantageous if the filler is formed from a fluorine-containing polymeric material. Exemplary is the polymeric fluorine-containing material PTFE, PVDF or FEP.

By way of example, PTFE has a coefficient of sliding friction against steel in the dry state of about 0.2 or less, whereas PE or rubber based material mixes against steel in the dry state have sliding friction coefficients of 0.3-0.6 (for PE) and 0.3-1.0 (for rubber) have.

For a variety of applications, it may also be useful if the material mixture itself comprises one or more fillers. The filler or fillers may be particulate or fibrous in this case. Also mixtures of particulate and fibrous fillers are conceivable.

Preferably, the polymeric fluorine-containing filler is present in an amount of 1 to 100 phr, preferably 2 to 50 phr (parts per hundred parts rubber = parts by weight per 100 parts of rubber) in the wear layer. This means that in the wear layer in the area in which the filler is embedded in the material mixture, according to the preferred embodiment, 100 to 100 parts by weight of polymer material is from 1 to 100 parts, preferably from 2 to 50 parts by weight, of the polymeric fluorine-containing filler. By way of example, good results are achieved with roller coverings having a wear layer of a material mixture with polymer material in which PTFE particles are embedded in an amount of 1 to 100 phr.

The polymeric fluorine-containing filler particles preferably have a size in the range from 1 μm to 2 mm, preferably in the range from 1 μm to 500 μm, particularly preferably in the range from 5 μm to 100 μm. In the specified size range, the best results are achieved with respect to the service life of the rolls according to the invention.

A suitable combination of materials to the above-mentioned filler proves to be when the polymer material of the material mixture is an elastomer, a thermoplastic or a thermoset or a mixture thereof. The elastomer used here is, for example, NBR (acrylonitrile-butadiene rubber), CSM (chlorine sulfonated polyethylene), NR (natural rubber), PU (polyurethane), HNBR (hydrogenated nitriles), SBR (styrene-butadiene rubber), CR (chlorine). Butadiene rubber) or a mixture thereof. In particular, PA (polyamide), PES (polyethersulfone) or PEEK (polyetheretherketone) or a mixture thereof is suitable as the thermoplastic. As the thermoset one or more epoxy resin (s) is preferably used.

Depending on the specific area of application of the roller, it may be expedient if the filler (viewed in the radial direction of the roller shell) is embedded in the material mixture over the entire thickness of the wear layer or if the filler is only in a portion of the thickness of the wear layer in the material mixture is embedded.

Of course, the filler in the areas where it is embedded in the material mixture may be evenly or irregularly distributed. In this context, the term evenly distributed means that in the region in which the filler is embedded, locally the same filler concentration prevails everywhere. The term evenly distributed in this context means that in the region in which the filler is embedded is a locally varying filler concentration.

Constructively, the dimensioning of the edge regions can be designed such that viewed in the longitudinal extent of the roller, the two edge zones each extend under the material web when the roller is used as intended, ie the material web overlaps with each of the two edge zones or the two edge zones each with the material web close exactly, ie that no overlap between the edge zones and the material web is given. Furthermore, it is possible that viewed in the longitudinal extent of the roller when used as intended, the roller between the material web and the edge zones in each case a distance remains.

The formation of a roll cover with only in the edge regions in the material mixture with polymer material embedded filler is then, for example, useful if a scraper is used only in the two edge zones of the roll cover or has contact only in the edge zones.

Furthermore, it is conceivable that the roll cover is formed only from the wear layer or that the roll cover is formed by the wear layer and one or more intermediate layers, which is or are arranged between the roll core and the wear layer and usually have a higher hardness as the wear layer. The one or more intermediate layer (s) may in this case be formed by a hard rubber material or a mixture thereof.

For a variety of applications of the roll according to the invention, it may also be useful if the two edge regions have a different hardness, in particular a greater hardness than the middle region. Typical hardness values for the wear layer are in the range between 10 and 300 P & J, preferably 10 to 100 P & J. In particular, it is advantageous if the edge regions 10 to 60P & J are harder than the middle region of the wear layer. A higher hardness results in higher breaking strength of the roll cover. Often, however, it is difficult to work with a hard roll cover due to limitations in papermaking or further processing. For example, the coating of paper works only with a soft roll cover. By providing a roll cover with harder edge zones than the central area, for example, a roll cover with increased breaking strength is provided, which is suitable for painting paper.

When the roller is used as intended, the surface of the wear layer can be brought into contact with the material web and / or with a belt and / or with a scraper. This use is given, for example, in almost every machine for refining a fibrous web or machine for producing a fibrous web.

Thus, for example by the invention, a machine for finishing a fibrous web or a machine for producing a fibrous web to be protected with a roll with a roll cover with a wear layer in which a squeegee or scraper is brought into tribological contact with the surface of the wear layer in a contact region, wherein the wear layer of the roll cover is formed from a material mixture with polymer material and in the material mixture at least in the region of the scraper or scraper in tribological contact, a filler is embedded which has a higher abrasion resistance and a lower coefficient of static friction and sliding friction than the material mixture.

Figur 1

eine abschnittweise Darstellung einer erfindungsgemäßen Walze im Querschnitt,

Figur 2

die erfindungsgemäße Walze der Figur 1 in perspektivischer Darstellung.

The invention will be further explained with reference to the following schematic drawings. Show it:

FIG. 1

a sectional view of a roller according to the invention in cross section,

FIG. 2

the roller of the invention FIG. 1 in perspective view.

The FIG. 1 shows a roll 1 according to the invention for a paper, board or tissue machine in cross-section in the region of an edge zone 2 (see FIG. 2 ). The roller 1 has a cylindrical roller core 3 and a roller cover 4 covering the lateral surface of the roller core 3. The roller cover 4 is connected to the roller core 3 with an adhesive layer 5. The roll cover has an intermediate layer 6 formed from hard rubber and an outer wear layer 7, which can be brought into tribological contact with a doctor in the intended use of the roll 1. The wear layer 7 comprises a material mixture 8 with an elastomeric polymer material such as NBR, in which in the two edge regions (see FIG. 2 ) is embedded a particulate fluorine-containing filler 9, which has a higher abrasion resistance and a lower coefficient of adhesion and sliding friction than the material mixture 8.

In the present case, the polymeric fluorine-containing filler 9 is formed from the material PTFE and is present in the wear layer 7 in an amount of 1 to 100 phr, preferably 2 to 50 phr (parts per hundred parts rubber). The PTFE particles 9 furthermore have a size in the range from 1 μm to 2 mm, preferably in the range from 1 μm to 500 μm, particularly preferably in the range from 5 μm to 100 μm. The filler 9 is in this case embedded over the entire thickness of the wear layer 7 in the material mixture 8. Of Further, the filler 9 in the edge regions 2, ie in the areas in which present filler 9 is embedded in the material mixture 8, evenly distributed in the material mixture 8.

1. 1) 100phr Elastomer
2. 2) 5-50phr Ruß
3. 3) 5-50phr Kieselsäure
4. 4) 1-100phr, bevorzugt 2-50phr PTFE-Partikel
5. 5) 1-40phr Vulkanisationsmittel (z.B. Peroxid, bevorzugt 1-10phr)
6. 6) 0,1-10phr Zusatzchemikalien, wie z.B. Aktivatoren (z.B. ZnO oder MgO,), Stearinsäure, Beschleuniger, Alterungsschutzmittel oder Prozessadditive allein oder in Kombination;

wobei die Materialmischung 8 durch die Bestandteile 1) bis 3), 5) und 6) gebildet ist.By way of example, the wear layer 7 in the edge regions 2 is constructed as follows:

1. 1) 100phr elastomer
2. 2) 5-50phr soot
3. 3) 5-50phr silica
4. 4) 1-100 phr, preferably 2-50 phr PTFE particles
5. 5) 1-40 phr vulcanizing agent (eg peroxide, preferably 1-10 phr)
6. 6) 0.1-10phr of adjunct chemicals such as activators (eg ZnO or MgO), stearic acid, accelerators, anti-aging agents or process additives alone or in combination;

wherein the material mixture 8 by the components 1) to 3), 5) and 6) is formed.

The wear layer 7 in the middle region 10 is identical to the wear layer in the edge zones 2 except for the PTFE particles, the wear layer 7 has no PTFE particles in the center region 10.

The FIG. 2 shows the roller 1 of FIG. 1 in perspective view. As can be seen, the wear layer 7 of the roll 1 has, seen in its length, two edge regions 2 delimiting the wear layer 7 and a center region 10 arranged between the edge regions 2, wherein the filler 9 is introduced into the material mixture 8 only in the two edge sections 2 is embedded.

Furthermore, the wear layer 7 has a greater hardness in the two edge regions 2 than in the middle region 10. The wear layer 7 has a hardness between 10 and 100 P & J in the middle region 10, the two edge regions 2 having a hardness greater by 10 to 60 P & J ,

Claims (12)

1. Roll (1) for a machine for processing a web, in particular a paper, board or tissue machine, having a cylindrical roll core (3) and having a roll cover (4) which covers the circumferential surface of the roll core (3) and which comprises a wear layer (7) which is located on the outside and is made of a material mixture (8) with polymer material in which, at least in some sections, there is embedded a filler (9) which has a higher abrasion resistance than the material mixture (8), the filler (9) also having a lower coefficient of adhesive and sliding friction than the material mixture (8), and the wear layer (7), viewed over its length, having two edge regions (2) delimiting the length of the wear layer (7) and a central region (10) arranged between the edge regions (2),
   characterized in that
   the filler (9) is embedded in the material mixture (8) only in the two edge sections (2).
2. Roll according to Claim 1,
   characterized in that
   the two edge regions (2) have a hardness which is different from, in particular greater than, that of the central region (10).
3. Roll according to Claim 1 or 2,
   characterized in that
   the filler (9) is particulate.
4. Roll according to one of Claims 1 to 3,
   characterized in that
   the filler (9) is formed from a fluorine-containing polymeric material.
5. Roll according to Claim 4,
   characterized in that
   the polymeric fluorine-containing material is PTFE, PVDF or FEP.
6. Roll according to one of Claims 1 to 5,
   characterized in that
   the material mixture comprises one or more filler(s).
7. Roll according to one of Claims 4 to 6,
   characterized in that
   the polymeric fluorine-containing filler (9) is present in an amount of 1 to 100 phr, preferably 2 to 50 phr (parts per hundred parts rubber) in the region of the wear layer (7) in which the polymeric fluorine-containing filler (9) is embedded in the material mixture (8).
8. Roll according to one of Claims 4 to 7,
   characterized in that
   the polymeric fluorine-containing filler particles (9) have a size in the range from 1 µm to 2 mm, preferably in the range from 1 µm to 500 µm, particularly preferably in the range from 5 µm to 100 µm.
9. Roll according to one of Claims 1 to 8,
   characterized in that
   the polymer material is an elastomer, a thermoplastic or a thermosetting plastic or a mixture thereof.
10. Roll according to one of Claims 1 to 9,
    characterized in that
    the filler (9) is embedded in the material mixture (8) so as to be distributed over the entire thickness of the wear layer (7).
11. Roll according to one of Claims 1 to 9,
    characterized in that
    the filler (9) is embedded in the material mixture (8) only in a section of the thickness of the wear layer (7) .
12. Roll according to one of Claims 1 to 11,
    characterized in that,
    during use of the roll (1) as intended, the surface of the wear layer (7) can be brought into contact with a web and/or with a belt and/or with a ductor.

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