WO2022063662A1

WO2022063662A1 - Method for producing an abrasive article, and abrasive article

Info

Publication number: WO2022063662A1
Application number: PCT/EP2021/075416
Authority: WO
Inventors: Johannes Huber
Original assignee: Robert Bosch Gmbh
Priority date: 2020-09-24
Filing date: 2021-09-16
Publication date: 2022-03-31
Also published as: DE102020212004A1

Abstract

The invention relates to a method for producing an abrasive article (100), in which abrasive grains are electrostatically scattered onto an abrasive article support that is coated with a binder, wherein the binder is made electrically conductive prior to the electrostatic scattering. The invention further relates to a correspondingly produced abrasive article (100).

Description

description

title

Method of making an abrasive article and abrasive article

The invention relates to a method of making an abrasive article in which a binder-coated abrasive article backing is sprinkled with abrasive grits.

State of the art

Methods for producing abrasive articles are already known in which a binder-coated abrasive article backing is sprinkled with a granular substance, in particular abrasive grains. Such methods are known, for example, from WO 2014/206967 A1. In the production of conventional abrasives, a binder is applied to a substrate, onto which abrasive grain is then scattered using an electrostatic scattering process. The electrostatic scattering process contributes to a desired alignment of the abrasive grains on the abrasive article.

Disclosure of Invention

A method of making an abrasive article is proposed in which abrasive grains are electrostatically scattered onto a binder coated abrasive article backing. According to the invention, the binder is made electrically conductive prior to electrostatic scattering. An abrasive article is for abrading a workpiece and includes at least one abrasive backing and abrasive grits disposed on at least one side of the abrasive backing. In particular, the abrasive article can be a coated abrasive article. In a coated abrasive article, abrasive grits are fixed to the abrasive article backing by means of the binder (often referred to as the make binder).

The abrasive article comprises an abrasive article backing, in particular a flexible one, with at least one layer. The backing for the abrasive article can include, in particular, paper, cardboard, vulcanized fiber, foam, a plastic, a textile structure, in particular a woven fabric, knitted fabric, knitted fabric, mesh, fleece, or a combination of these materials, in particular paper and fabric, in one or more layers. The abrasive article backing, which is particularly flexible, gives the abrasive article specific properties in terms of adhesion, elongation, tear and tensile strength, flexibility and stability.

The abrasive article has a surface intended for grinding, i.e., abrasive, on that side of the abrasive article to which abrasive grits are fixed by the binder. During a grinding process, the abrasive surface of the grinding article is moved over a workpiece to be machined, so that a grinding effect is produced by means of the grinding grains arranged on the abrasive surface. In principle, the abrasive article can be in different ready-made forms, for example as a grinding wheel or as an abrasive belt, as a sheet, roll, strip or even as a web of abrasive articles (e.g. in production). In particular, the grinding article can be manufactured for use with grinding machines such as random orbital grinding machines or also for manual grinding. For example, the abrasive article can be implemented as a hand sanding sheet, as a sanding belt or as a sanding disk covered with velor.

The abrasive article has abrasive grits on at least one surface of the abrasive article backing. Abrasive grain should be understood to mean an element that has a deforming and/or abrasive effect on an object to be machined, ie on a workpiece. An abrasive grain can in particular be made of a mineral and/or ceramic material, for example diamond, corundum, silicon carbide, boron nitride or the like. In one embodiment, the abrasive grains are realized by aluminum oxide particles with a particle size between 7 μm and 300 μm. In particular, the abrasive grain can have any geometric configuration that appears reasonable to a person skilled in the art. The abrasive grain can be so-called shaped abrasive grain or broken abrasive grain. An abrasive grain causes friction and temperature development on the object to be processed, which has a deforming and/or abrasive effect on or in the object to be processed.

The abrasive grains are at least pre-fixed, in particular fixed, on the abrasive backing with the binder, in particular in a desired position and/or distribution. Starting from the prior art, a person skilled in the art is basically familiar with suitable binders for fixing abrasive grains on the abrasive article backing. In this case, the abrasive article backing is coated with the binder before it is sprinkled with abrasive grains.

The abrasive grains are sprinkled into the not yet hardened binder by means of electrostatic scattering and are thus bound to the abrasive article backing. “Electrostatic scattering” should be understood to mean, in particular, a scattering process in which electrically polarizable abrasive grains are accelerated by a, in particular static, electrical field (possibly against the force of gravity) onto the abrasive article backing coated with binder. The electric field has a voltage of 1 kV to 60 kV, for example. A targeted distribution, in particular a targeted scattering density, of the abrasive grains on the abrasive article backing can advantageously be achieved in this way.

In one embodiment of the method for producing an abrasive article, a non-intrinsically conductive binder, in particular a non-aqueous binder, is used as the binder. “Not intrinsically conductive” is to be understood as meaning that the binder per se, ie without further—according to the invention—processing, has low conductivity or no conductivity at all. In particular, a conductivity of the binder is less than 0.5 pS/m, most particularly less than 0.1 pS/m. For example, the non-intrinsically conductive binder can be a hot-melt adhesive, in particular a two-component polyurethane binder, an epoxy resin or a UV-curable resin.

According to the invention, the binder is made electrically conductive prior to electrostatic scattering. “Make electrically conductive” means that the intrinsically non-conductive binder is treated in such a way that it is henceforth conductive. “Conductive” means in particular an electrical conductivity of at least 0.5 pS/m. In one embodiment of the method, after it has been made conductive, the binder has a conductivity of at least 0.5 pS/m, in particular at least 1 pS/m, very particularly at least 5 pS/m. The conductivity of the binder is determined in particular when it is applied to the abrasive article backing or in the liquid state before application (for example using a two-electrode conductivity measuring instrument such as the Qcond 2400 from VWR). In particular, the binder is made conductive by introducing and/or applying an electrically conductive material that is not part of the binder. In this context, an “electrically conductive material” is to be understood in particular as meaning a material which enables electrical charge transport in the binder. In particular, the electric charge transport can take place by means of electrons and/or by means of ions.

Since the distinction between "not intrinsically conductive" and "made conductive" is relevant in the context of the present invention, it should be noted that a binder is considered not intrinsically conductive if it cannot be used as a counter electrode in an electrostatic scattering process, because no electrical field can be built up between the electrodes (except possibly locally at the contact point) that can be used to scatter the abrasive grains. On the other hand, the binder is considered to be conductive if it has such a high conductivity (intrinsic or caused according to the invention) that it can be used as a counter-electrode in an electrostatic scattering process. For example, distilled water (depending on its purity) has a conductivity of approx. 15-25 pS/m. The conductivity of a non-intrinsically conductive two-component polyurethane binder is significantly lower at less than 0.1 pS/m. This binder is considered not intrinsically conductive. The addition of 5 wt.% carbon black increases the conductivity to the order of 5 pS/m. On the other hand, adding 1 wt% of an ionic liquid increases the conductivity to the order of 0.6 pS/m, adding 2 wt% to the order of 1.2 pS/m. The two-component polyurethane binder so modified is considered to be rendered conductive. A classic, conductive binder - such as phenolic resin dissolved in water - on the other hand has an intrinsic conductivity of the order of approx. 100 pS/m, which is therefore approximately 1000 times greater than the conductivity of the non-intrinsically conductive binder. The values are determined in particular using a two-electrode conductivity measuring instrument such as the Qcond 2400 from VWR or the like.

In one embodiment of the method, the binder is mixed, in particular mixed or blended, with a conductive additive, in particular carbon black and/or carbon fibers and/or a conductive organic compound such as an ionic liquid, to make it conductive. In this way, a particularly simple procedure for making conductive can be specified. A “conductive organic compound” is to be understood in particular as a chemical substance and/or a combination of a plurality of chemical substances which are based on the element carbon and contain at least hydrogen, oxygen and/or nitrogen in addition to carbon. In particular, an organic compound includes at least one organic salt. In particular, the organic compound can be in the form of at least one ionic liquid and/or a conductive polymer. In particular, ionic liquids have good electrical conductivity, in particular ionic conductivity, which advantageously allows good polarizability of the binder that has been made conductive, in particular in the case of an electrostatic scattering process. In addition, using an ionic liquid, an electrical conductivity that is independent of atmospheric humidity, in particular special an ionic conductivity can be achieved. In particular, the organic compound, preferably the ionic liquid, can comprise an imidazole ring and/or an imidazolium ion, in particular an imidazolium cation. In particular, the ionic liquid can include l-butyl-3-methylimidazolium tetrafluoroborate. A “conductive polymer” is to be understood as meaning a plastic which has an electrical conductivity which is in particular comparable to the electrical conductivity of a metal. The intrinsically conductive polymer can include, for example, poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS).

In one embodiment it is conceivable to enrich the binder with carbon black. In order to obtain good conductivity, the concentration of carbon black in the coating must be high enough to ensure a continuous conductive path through the coating. Because the conductivity of soot is isotropic and does not depend on the alignment of the soot along any particular direction, a necessary threshold concentration of soot to effect conductivity is relatively low. The binder is preferably enriched with at least 1% by weight of carbon black, in particular with at least 2.5% by weight of carbon black, very particularly with at least 5% by weight of carbon black. Thus, the carbon black is in a concentration sufficient to modify the binder that encapsulates it with a conductivity of 0.5 to 6 pS/m.

It should be noted that in this way the binder can be made conductive over its entire volume. Advantageously, no conductive additive is applied to the surface of the binder applied to the backing of the abrasive article, which could adversely affect embedding and/or binding of the abrasive grains.

In an alternative or additional embodiment of the method, the binder is coated with a conductive film, in particular a layer of carbon black and/or a film of a conductive organic compound, to make it conductive. In this way, a particularly simple procedure for making conductive can be specified. For example, it is conceivable that the binder before the process step of electrostatic scattering with a thin Spray layer of ionic liquid. It should be noted that in this way the binder can be rendered conductive across the surface that it forms on the abrasive article backing - without changing the bulk properties of the binder. In particular, it can be achieved in this way that the crosslinking properties of the binder in the volume range are not adversely affected by the additive. Furthermore, it is proposed that a maximum layer thickness of the conductive film is less than 30 μm, in particular less than 1 μm, in particular less than 100 nm. As a result, the consumption and/or the need for coating material can advantageously be kept low. In addition, a change in the surface of the uncoated binder can be kept small by a small layer thickness. In addition, a small layer thickness advantageously enables easier and/or rapid diffusion of the conductive film into the air after the scattering process.

In one embodiment of the method, the binder is operated as a high-voltage electrode, in particular as a counter-electrode, during the electrostatic scattering.

According to the method according to the invention, disadvantages of the prior art can be overcome. When electrostatically sprinkling abrasive articles that use non-aqueous binders, such as hotmelt adhesives or water-free PU resins, the intrinsic electrical conductivity of the binders is often either not pronounced or only insufficiently pronounced (typically in the range of <0.1 pS/m). In order to nevertheless be able to carry out electrostatic scattering, according to the prior art a counter-electrode is used which—seen from the first electrode—is arranged behind the abrasive article support to be scattered. This counter-electrode causes the abrasive grains to be accelerated in the direction of the counter-electrode onto the backing of the abrasive article. The electrostatic scattering has the effect that the abrasive grains are not necessarily aligned orthogonally to the surface of the abrasive article backing, but always orthogonally to the counter electrode towards which they are moving. This is particularly the case with non-planar surface structures of the abrasive article backing, for example with a binder coated layered foam, binder coated mesh or the like. The intrinsic conductivity incorporated or applied according to the invention into and/or onto the binder now makes it possible to overcome these disadvantages of the prior art. Since the electric field lines now emanate from the surface structures to be coated, such as fibers, foam pores or the like, instead of from a counter-electrode behind the abrasive article backing, the abrasive grains are increasingly aligned orthogonally to the surface or to the surface structure of the abrasive article backing to be coated. For example, in the case of curved surface structures (such as occur in a network in the form of fibers), these surface structures can be sprinkled with abrasive grains protruding orthogonally to the surface. Such an alignment of abrasive grains is particularly advantageous for abrasive articles with non-planar, flexible backings, such as knitted fabrics, because then even if the surface of the abrasive article is deformed during a grinding operation, the abrasive grain will continue to be orthogonal to the workpiece instead of avoiding it. In particular when sanding edges or corners with tight radii of curvature - for example in the case of foam blocks or knitted nets - it is not possible to align the abrasive grain orthogonally to the surface with classic methods (as described above or with mechanical sanding methods). The proposed invention now permits the manufacture of such abrasive articles. Furthermore, a removal rate and a service life of the abrasive article can be improved by the method according to the invention. Furthermore, a separate counter-electrode can be dispensed with.

In one embodiment of the method, the binder is grounded during electrostatic scattering. Although the proposed method is fundamentally conceivable with any polarity (ie grain bed and binder each positive or negative), it has proven to be advantageous, particularly when producing a web of abrasive articles, if earth potential is applied to the binder. In this way it can be achieved that the charge is not discharged via grounded, non-insulated parts of the production plant. Alternatively, it is conceivable to subject the binder to high voltage during the electrostatic spreading. This variant is particularly suitable for relatively small, Abrasive article pads to be sprinkled individually, such as flower abrasive articles or the like.

It is proposed to implement the method according to the invention in one embodiment as a roll-to-roll method, with the abrasive article backing being provided and used in the form of an abrasive article backing web roll, in particular being unrolled, sprinkled and then rolled up again onto an abrasive article web roll . In particular, an abrasive article in the form of a web of abrasive articles is made in this manner. In this case, a material web designates an embodiment of the abrasive article backing which is extended in a preferred direction and which is or is typically rolled up on a roll.

The electrical connection of the binding agent for realizing the high-voltage electrode, in particular in a realization of the method as a roll-to-roll method, can take place by making an electrical contact, for example by means of an electrically conductive carbon fiber brush. Alternatively or additionally, the electrical connection of the binder can also be achieved by means of a corona discharge, which is effected between the binder and an electrode arranged at a direct distance from the binder without contact with the binder, with the binder being (approximately) grounded or brought to high voltage will. Due to the electrical conductivity and the low current intensities within the binder, the binder has a uniform potential almost everywhere (at least in the area where the scattering takes place), even if the binder is only electrically (contacting or non-contacting) connected to the binder at one or a few points voltage source is connected.

Furthermore, an abrasive article, in particular a web of abrasive articles, is proposed which is produced by the method according to the invention. The abrasive article has abrasive grits applied to the abrasive article backing. Abrasive grains are known from the prior art. The abrasive grains are bonded directly to the backing of the abrasive article with the help of the binder. The abrasive article has a surface intended for grinding, ie an abrasive surface, in particular on that side of the abrasive article on which the abrasive grains are fixed. During a grinding process, the abrasive surface of the grinding article is moved over a workpiece to be machined, so that a grinding effect is produced by means of the grinding grains arranged on the abrasive surface. In principle, the abrasive article can be made up in different forms, for example as a grinding wheel or as an abrasive belt, as a sheet, roll, strip or also as a web of abrasive articles (e.g. in production).

In one embodiment, the abrasive article is implemented as a foam abrasive article having a foam abrasive article backing. The abrasive foam article, in particular the base body that gives the abrasive foam article its essential shape, can in principle be present in different forms, for example as a block, as a disk, as a roll, as a band, as a strip or the like. Further, the foam abrasive article can also be made for use with grinding machines such as random orbital sanders. The base of the foam abrasive article includes at least one foam. In particular, the foam can be porous and/or air-permeable. Furthermore, the foam can be designed as a closed-cell, an open-cell or a mixed-cell foam. In particular, the foam is flexible and, in particular, elastically deformable. The base body made of foam gives the foam abrasive article its essential shape and specific properties with regard to flexibility and stability, in particular with regard to elasticity, extensibility, compressibility, shearability, tear strength and tensile strength. In an exemplary embodiment of the foam abrasive article, the base body can be made of a polyurethane foam, in particular consist of this. Alternatively, the base body can in principle also be made of ethylene-vinyl acetate copolymer (EVA), polyethylene (PE), polypropylene (PP), acrylonitrile-butadiene rubber (nitrile rubber, AB or NBR), polystyrene (PS), polyurethane (PE) or the like be realised.

In one embodiment of the abrasive article, it is realized as a mesh abrasive article with an abrasive article backing made of a carrier mesh, in particular a textile structure. The carrier network is understood to mean an essentially flat structure which has a large number of webs and nodes at which the webs are connected to one another. The webs define openings, which are formed immediately during the manufacture of the planar structure. For example, a carrier net can be directly extruded in one piece or be connected from thread-like or strip-like strands by knitting, weaving, braiding, knitting, crocheting, sewing, embroidering, lace-making or knotting to form a flat structure. Alternatively, a carrier network could also be produced, for example, by means of an injection molding process. The openings are created directly during production of the fabric. In one embodiment, the support network has openings whose density is in the range from 5 to 500 openings per cm ² , in particular in the range from 30 to 350 openings per cm ² , very particularly in the range from 60 to 200 openings per cm ² . This property sets a carrier net apart from structures in which a full-surface structure is subsequently perforated or slit. In one embodiment, a carrier net contains plastic, in particular polyamide, polyester, polyolefins, plastic with styrene components or mixtures thereof, very particularly polyamide, polyester, or mixtures thereof. In one embodiment, the support mesh is made of nylon. The abrasive grains are attached to the webs and/or the nodes of the carrier mesh by means of the binder. The surface coated with abrasive grain typically represents an essentially flat surface, which however has a surface structure formed by the openings and curves of the webs.

In principle, alternative, non-coated abrasive articles are also conceivable, such as bonded abrasive articles. Bonded abrasive articles are typically synthetic resin-bonded cutting and grinding wheels, which are familiar to those skilled in the art. For synthetic resin-bonded cutting and grinding wheels, a mass is mixed from abrasive minerals and fillers, powdered resin and liquid resin, which is then pressed into cutting and grinding wheels of various strengths and diameters. In particular, the cutting and grinding wheels also include fabric layers made of glass fiber. The compound typically hardens at approx. 180 °C. In combination with the method according to the invention, advantages according to the invention can also be achieved with such abrasive articles. In particular, it is also conceivable already to subsequently sprinkle finished bonded abrasive articles with further abrasive grains (for example on an edge region) using the method according to the invention.

Furthermore, abrasive articles with voluminous, in particular rotationally symmetrical, bodies are also conceivable as abrasive article backings, which can be sprinkled with abrasive grains by the method according to the invention. Such voluminous bodies can, for example, have a spherical, hemispherical, cylindrical, conical or other geometric shape, in particular a rotationally symmetrical shape, and their surface can be sprinkled electrostatically with abrasive grains. For example, spherical abrasive articles can be produced that have abrasive grains on their surface that are aligned perpendicularly to the surface by electrostatic scattering.

It should be mentioned that the abrasive article sprinkled with abrasive grains can also be coated with a top binder, which is applied in particular in layers over the abrasive grains fixed to the abrasive backing by means of the binder. The top binder connects the abrasive grains firmly to each other and to the abrasive backing. Suitable top coats from the prior art are well known to those skilled in the art.

drawings

The invention is explained in more detail in the following description on the basis of exemplary embodiments illustrated in the drawings. The drawings, the description and the claims contain numerous features in combination. The person skilled in the art will expediently also consider the features individually and combine them into further meaningful combinations. The same reference symbols in the figures designate the same elements.

Show it:

Figure 1 is a process diagram illustrating the method of making an abrasive article of the present invention; FIG. 2 shows a schematic side view of an exemplary embodiment of a spreading machine for carrying out the method according to the invention;

FIG. 3 shows a schematic sectional view of an abrasive article during the implementation of the method according to the invention;

Figure 4a, b the technical effect of the invention (b) compared to the

Method (a) known in the prior art.

Referring to Figure 1, a process diagram illustrating one embodiment of the method 100 of the present invention for making an abrasive article 10 (as depicted in Figure 3) is shown. FIG. 2 shows a production structure 50 suitable for carrying out the method 100 illustrated in FIG. 1. FIGS. 1 and 2 are explained together below.

In a first method step 102, a non-intrinsically conductive binder 14 is provided, here a two-component polyurethane binder. In the production setup 50 shown in FIG. 2, this method step is not shown separately.

In process step 104, the binder 14 is rendered conductive by mixing it with 5% by weight of carbon black. For this purpose, the carbon black is first dispersed and then mixed with the binder 14 . A conductivity of the binding agent 14 of 6 pS/m is thereby achieved.

In process step 106, the abrasive article backing 16 is provided. In the roll-to-roll method shown in Figure 2, this is achieved by unwinding and threading a web of paper goods 52 into the production structure 50, so that the web of paper goods 52 is transported counterclockwise via the transport rollers 54 in the direction of the arrow and thus in the direction in which the web of paper goods 52 extends . Not shown in FIG. 2 is a roller carrier for the continuous unwinding of the input material, ie the paper web 52. The abrasive article 10 produced by the method according to the invention, ie the coated paper web 52, is rolled up on roller carriers, also not shown in FIG. In process step 108, the abrasive article backing 16 is coated with the previously prepared binder 14, ie, made conductive. The binder 14 is applied to the web of paper goods 52 as an abrasive article backing 16 by means of a doctor blade 56 .

In method step 110, the binding agent 14 applied to the abrasive article backing 16 is contacted by means of a fine conductive brush 58 and in this way set up for use as the first high-voltage electrode 60. The electrical potential of the binding agent 14 is thereby grounded by means of the brush 58 .

In method step 112, abrasive article backing 16 is sprinkled electrostatically with abrasive grains 12 by generating an electric field 62 between high-voltage electrode 62 (ground) and another high-voltage electrode 64. A potential of approx. U=40 kV relative to ground is applied to the further high-voltage electrode 64 - represented here by the voltage source 66. The further high-voltage electrode 64 is realized by an inclined plane 68 on which the abrasive grains 12 to be scattered trickle down gravimetrically (provided by a reservoir 70) by sliding on the incline 68 due to gravity. Because the metal inclined plane 68 is operated as a further high-voltage electrode 64 , the abrasive grains 12 become electrostatically charged as they move across the inclined plane 68 . The electrostatic charge causes the abrasive grains 12 to repel each other and thus distribute themselves evenly spaced over the inclined plane 68, in particular in the direction of their sliding movement as well as in the lateral direction (ie in the direction into the plane of the figure). When the abrasive grains 12 have reached the end of the inclined plane 68, they are electrostatically scattered onto the abrasive article backing material web, ie here the paper material web 52, which is moved along the inclined plane 32. The inclined plane 68 serves as a grain bed for the abrasive grains 12. When the abrasive grains 12 jump onto the counter-electrode, here the high-voltage electrode 60 in the form of the binding agent 14, the abrasive grains 12 also align themselves in the electric field 62. Once they have reached the binder 14 , the abrasive grains 12 are bonded to the abrasive article backing 16 by the binder 14 and are thus fixed to the abrasive article 10 . In process step 114 , the abrasive article backing 16 coated with the binder 14 and sprinkled with the abrasive grits 12 is baked using a heating oven 72 . In the process, the abrasive grains 12 are firmly bound in the binding agent 14 . In a further process step, a cover binder 18 can also be applied to the abrasive article 10 produced in this way (cf. FIG. 3).

FIG. 3 shows a detail of an exemplary embodiment of an abrasive article 10 according to the invention with abrasive grains 12 in a schematic sectional representation. Abrasive article 10, in the illustrated embodiment, is a coated abrasive article 10 having an abrasive backing 16. Abrasive backing 16 serves as a flexible backing for abrasive grains 12. Abrasive grains 12 are secured to abrasive backing 16 by binder 14. During the implementation of the method according to the invention (cf. FIG. 1), the binder 14 is used as a high-voltage electrode 60 for electrostatically scattering the abrasive grains 12 . This is indicated here by the electrical interconnection 74 on the left-hand side of FIG. 3, which also shows a connection to a voltage source 66 (as in FIG. 2).

The layer of binder 16, implemented here as a base binder, and abrasive grains 12 is additionally coated with a top binder 18, for example made of phenolic resin.

Finally, FIG. 4 shows the effect of the method (b) according to the invention compared to methods of the prior art (a). FIG. 4a shows an abrasive article backing 16 which is/was sprinkled with abrasive grains 12 electrostatically. The surface of the abrasive article backing 16 does not have an intrinsically conductive binder or one that has been made conductive (not shown in more detail here), but merely a non-conductive binder. Consequently, there is no polarization on the surface of the abrasive article backing 16, so that the electric field 62 runs from the additional high-voltage electrode 64 to the high-voltage electrode 60, which are each formed by one electrode here. Consequently, the jumping abrasive grains 12 are only aligned along this electric field 62, so that the abrasive grains 12 on the surface of the abrasive article in the same direction (here all point-down).

FIG. 4b also shows an abrasive article backing 16 which is/was sprinkled with abrasive grains 12 electrostatically. In contrast, the abrasive article backing 16 has a binding agent 16 that has been rendered conductive on its surface. Consequently, polarization takes place on the surface of the abrasive article backing 16, so that the electric field 62 runs from the further high-voltage electrode 64 to the high-voltage electrode 60—here realized by the binding agent 16. In this case, the abrasive grains 12 align orthogonally to the surface of the abrasive article backing 16 (abrasive grains 12 protrude with their tips). Consequently, the jumping abrasive grains 12 are aligned orthogonally to the surface of the abrasive article backing 16.

Claims

Expectations

A method of making an abrasive article (100) comprising electrostatically scattering abrasive grains onto a binder coated abrasive article backing (14,104), characterized in that the binder is rendered electrically conductive prior to electrostatic scattering.

2. The method according to claim 1, characterized in that a non-intrinsically conductive binder, in particular a non-aqueous binder, is used as the binder.

3. The method as claimed in one of the preceding claims, characterized in that the binder is mixed with a conductive additive, in particular soot and/or carbon fibers and/or a conductive organic compound, to make it conductive.

4. The method according to any one of the preceding claims, characterized in that the binder to make it conductive is coated with a conductive film, in particular a layer of carbon black and/or a conductive organic compound.

5. The method according to any one of the preceding claims, characterized in that the binder has a conductivity of at least 0.5 pS/m, in particular of at least 1 pS/m, very particularly of at least 5 pS/m after it has been made conductive.

6. The method according to any one of the preceding claims, characterized in that the binder is operated during the electrostatic scattering as a high-voltage electrode, in particular as a counter-electrode.

7. The method according to claim 6, characterized in that the binder is grounded during the electrostatic spreading.

8. Method according to one of the preceding claims, characterized in that the method is implemented as a roll-to-roll method.

9. Abrasive article (100) manufactured according to one of the preceding claims, in particular abrasive article web manufactured according to claim 8.

10. The abrasive article (100) of claim 9 implemented as a foam abrasive article having a foam backing abrasive article or as a mesh abrasive article having a backing mesh abrasive article.