FI115153B - Roll surface coating and method of making roll surface coating - Google Patents

Description

115153

BACKGROUND OF THE INVENTION The present invention relates to a process for producing a roll coating of a papermaking machine or the like, comprising forming a first layer on a surface of a 5-roll body and applying a chemical coating to the interface between the first layer and a working coating, or forming a first layer, forming at least one intermediate layer on the first 10 layers, and forming an operating coating on the surface of the intermediate layer, and in which method a chemical bond is formed at the interface between the intermediate layer and the operating coating.

The invention also relates to a roll coating on a roll of a papermaking machine or the like, which roll coating comprises a first layer and a working coating as the top layer of the roll, and the working coating and the underlying layer are chemically bonded to one another.

It is known that wet portions of a papermaking machine or the like, such as a board machine, use rolls having roll rolls on the roll body. a first layer (a water barrier layer) protecting against the corrosion and a topcoat over the first layer. Such rollers include e.g. paper machine wet head press rolls. The first layer prevents moisture from penetrating into the track body, thereby preventing the track body from being exposed to corrosion. Both the first layer and the coating are based on polyurethane, whereby the layers are joined together by a chemical reaction. A typical roll coating manufacturing method is rotational molding, in which, as the roll frame rotates about its axis, a flat coating is formed on the roll body by extrusion of polymeric extruder. By this method, a first layer is formed first and immediately thereafter an intermediate layer and / or a working coating.

It is known from Fl 92419 (EP 487477) to provide a roll coating having a water barrier layer and the actual coating which may be a polyurethane elastomer. The polyurethane elastomer serves as a matrix material, for example, 115153 2 for oxides and carbides which are doped with the coating to improve wear resistance and process engineering properties.

It has been found that the chemical bond between the first layer or the intermediate layer and the application coating may not be sufficient. In principle, the strength of the chemical bond could be improved by using adhesives, for example, but the problem is that the first or intermediate layer is only reactive for a few minutes. After this, the layer hardens and is no longer in a state where it reacts with the application coating. Thus, separate bonding and application coating formation should be done in this short period of time, which is not possible with current techniques.

The method according to the invention is characterized in that, prior to forming a coating for use on the surface of the top layer, which top layer is a first layer or an intermediate layer, corrosion-resistant particles are introduced such that at least some of the particles are partially submerged in the top layer. The roll coating according to the invention is characterized in that the interface between the working coating and the layer below it has corrosion-resistant particles.

By the process according to the invention, a roll coating can be made such that a mechanical locking device, in addition to a chemical bond, can be achieved between the first layer or intermediate layer and the working coating. 25 tus between the layers. Since particle scattering can be performed as a continuous process between the first layer or intermediate layer and the formation of a>> *: * 'working coating, the formation of chemical bonds between the layers is not compromised.

:] · '30 The roll coating according to the invention is used on a wet end of a paper machine or the like in press rolls, suction rolls and groove rolls. Also suitable are rollers for an adhesive press. A typical application is one where the ambient temperature is up to 70 ° C.

: 35 To achieve mechanical locking between layers, corrosion-resistant particles can be used at the interface of the layers. The fact that the particles are not susceptible to corrosion is important in wet conditions - 3,115,753 otherwise roll performance could be dramatically reduced with roll life. The corrosion-resistant particles may be metal and / or ceramic particles having an average diameter of not more than 1 mm, preferably 30 μηη - 1 mm. Too small particles do not achieve good mechanical locking, too large particles adversely affect the roll properties. The particles cover up to 40% of the surface area of the first layer, leaving enough free space for the formation of chemical bonds between the first layer and the application coating. The particles are preferably polygonal, so that the area forming the lock is as large as possible. The particles may be substantially uniformly distributed over the entire surface area or may be present only on a portion of the surface area. It is also possible that the particles are applied at different densities to different parts of the surface. However, generally, the above 40% coverage of 15% is not exceeded locally.

The material of the particles may comprise collectors such as metal oxide, metal carbide, metal nitride or metal boride. Suitable ceramics include, for example, alumina (Al 2 O 3), titanium dioxide (TiO 2), zirconia (ZrO 2), silica (SiO 2), tungsten carbide (WC), titanium nitride (TiN) and titanium boride (TiB 2). The material of the particles may also comprise metal, such as acid-proof steel. Preferably, the particles are surface treated. y. non-stick ceramic materials.

* * · * · 25 It is possible that the roll coating has only the first layer .. "" ros and a working coating having an interface between the particles in question. * * ·: Another possibility is that the first layer and the application layer: ·· ·: There is one or more intermediate layers between the coating, at least at the interface between the top intermediate layer and the working coating: · 30 there are particles It is also possible that there are particles at more than one interface, or there are particles at all interfaces between roller coatings. a chemical bond is formed, and what is said about the number of particles on the surface of the first layer is also applicable to the other layers, where particles that cause locking are introduced onto the surface.

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The roller coating is preferably manufactured by rotary molding. The material of the first layer, the interlayer (s) and the coating is polymeric material. Preferably, the material is a polyurethane-based material which crosslinks and cures, for example by means of a curing agent doped therein. Polyurethane elastomers such as TDI resins (toluene diisocyanate ethers and esters), MDI resins (diphenylmethane diisocyanate esters and ethers), PPDI resins (para-phenethylene) or CHDI resins (cyclohexyl diisocyanate-10 ti). The material of the first layer is substantially harder than that of the working coating. The first layer may contain fillers. In addition to preventing the passage of water, the first layer may serve as a nip load distribution layer.

The first layer is first formed, and while it or the intermediate layer formed on its surface is still in a gel-like state (not cured), anti-corrosion particles are sprinkled on the surface of the layer. At least most of the particles are partially submerged in the water barrier or interlayer so that one side is above the surface of the layer. When the first layer or intermediate layer is still in the reactive state, a working coating is formed thereon. In this case, the part of the particles above the surface of the water barrier or intermediate layer penetrates into the working coating. When the first layer or intermediate layer and the operating coating adhere to the particles firmly, a mechanical lock is formed between the layers in addition to the chemical bond. A chemical bond is formed between the first layer or intermediate layer and the working coating as the * 1 t materials harden and crosslink.

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In the following, the invention will be described with reference to the accompanying drawings, in which P> 30, Figure 1 illustrates the preparation of a roll coating by a method according to the invention, in which the roll to be coated. The body is shown in section, and: Figure 2 shows an enlarged view of area A in Figure 1.

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The figures illustrate an example where the roll coating has only a first layer and a working coating.

The roll coating is formed in the method shown in Figure 1 by the rot-5 molding technique. During casting, the roll body 1 is rotated about its axis. The first polyurethane-based material constituting the layer 5, in this case the waterproofing layer, is extruded as a strip from the die 2 as the die moves in the axial direction. The dispenser 3 of the particles 6 moves behind the nozzle 2 at a suitable spacing of 10. Behind the die 2 and the particle dispenser 3 there is a die 4, from which a polyurethane-based material forming the working coating 7 is pressed. There must be a slight delay between particle dispensing and application coating so that the particles 6 partially submerge in the first layer 5, whereby the particles provide effective mechanical locking between the first layer 5 and the application coating 7.

Fig. 2 is an enlarged view of the area A of Fig. 1. Between the first layer 5 and the application coating 7 is an interface B with a particle 6 positioned such that a portion of the particle 6 is submerged in the first layer 5 and a portion penetrates the application coating 7. The particles 6 are preferably polygonal, with the adhesive surface between the particles 6 and the surrounding layers 5 and 7 being as large as possible.

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The invention is not limited to the foregoing, but may vary within the scope of the claims. There may be one or more intermediate layers between the first layer and the operating surface.

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Claims (10)

A method of making a roll surface coating for a roll in a paper machine or the like, in which process 5 - a first layer (5) is formed on the surface of a roll body (1), and on the first layer (5) a working coating ( 7), and in which process a chemical bond is formed on the interface (B) of the first layer (5) and the use coating (7), or on the surface of the roller body (1), a first layer (5) is formed on the first layer. (5) at least one intermediate layer is formed and on the surface of the intermediate layer (5), a use coating (7) is formed, and in which process a chemical bond is formed at the interface of the intermediate layer and the use coating (7), characterized in that before the formation of the use coating (7) on the surface of the outermost layer, which outermost layer being the first layer (5) or the intermediate layer, corrosion-resistant particles (6) are caused such that at least some of the particles (6) partially fall into the outermost layer. 20 Process according to claim 1, characterized in that the particles (6) are corrosion resistant metal and / or ceramic particles, whose average diameter is at most 1 mm, preferably 30 µm - 1 mm. I> I I t I · Method according to claim 1 or 2, characterized in that the pairs of articles (6) cover a maximum of 40% of the surface of the first layer or the intermediate layer. »I · *« · • » Method according to any of the preceding claims, characterized in that the first layer (5), the intermediate layer (s) and the use coating (7) are formed in rotary casting technique. I »t 5. Roll surface coating on a roll in a paper machine or the like, said roll surface covering comprising a first layer (5) and a use coating: (7) as the outermost layer of the roll, and the use coating (7) and the layer underneath this existing layer is chemical bonded with each other,. characterized in that at the interface between the use coating (7) 11515? and there are corrosion-resistant particles (6) beneath this existing layer. Roll surface coating according to claim 5, characterized in that the particles (6) are metal or ceramic particles. Roll surface coating according to claim 5 or 6, characterized in that the particles (6) have an average diameter of no more than 1 mm and their shape is angular. 10 Roll surface coating according to any one of the preceding claims 5-7, characterized in that the material of the particles (6) is a metal oxide, such as alumina (Al2 O3), titanium dioxide (TiO2), zirconia (ZrO2) or silica (SiO2), a metal carbide, sasorn tungsten carbide (WC), a metal nitride, sasorn titanium nitride (TiN), a metal boride, sasorn titalboride (TiB2), or a metal, sasorn acid-resistant site. Roll surface coating according to claim 5, characterized in that between the first layer (5) and the use coating (7) there is one or more intermediate layers, with corrosion-resistant particles (6) being on the interface of one or more layers in the rolling surface coating. • | Roll surface coating according to any of the preceding claims 5-9, characterized in that the material of the layers in the rolling surface coating is a polymeric material, preferably a polyurethane-based material. »» 1 * »1 ·