DE3043796A1 - FLEXIBLE ABRASIVE, EXAMPLE IN THE FORM OF SHEETS, TAPES, DISKS OR THE LIKE - Google Patents

Description

KÖHLER GERNHARDT GLAESER PATE NTAN WXlTE

Approved by the European Patent Office

MUNICH j TELEPHONE! Μς-555 «76/7

OR. E. WIEGAND. 1 _ Λ _ TELEGRAMMEi CARPATENT

DR. M. KÖHLER '\ <-> TELEXi 5290 * 8 KARP D

DtPL-ING. C. GERNHARt) T

HAMBURG
DIPL.-ING. ]. GLAESER

DIPl.-ING. W. NIEMANN · D-8 0 0 0 MÖNCHEN

OFCOUNSa HERZOG-.WILHEIM-STR.

November 19, I98C W 43 376/79 12 / Sr / Ld

C. Klingspor GmbH
Haiger

Flexible abrasive * for example in the form of Sheets, ribbons, discs or the like

The invention relates to a flexible abrasive which is often used in the field in question here also referred to as "coated abrasives". Such a flexible abrasive can be in the form of, for example of sheets, ribbons, discs or the like. It usually consists of a flexible base, for example made of paper or fabric, and a binder layer is first applied to this base, on which abrasive grain is then sprinkled. Usually, a top layer is then applied, which in in many cases consists of the same material as the binder layer. This binder is in many cases a thermosetting plastic, and it can advantageously be a modifiable phenolic resin, epoxy resin or polyester resin or the like be. Such binders are known.

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TJm a really "flexible" To obtain abrasives, the abrasive produced in this way is "flexed". This flexing means that that Abrasives usually flexed one after the other in two different directions, i.e. practically broken by moving it over rollers with a small radius of curvature or over curved edges. One this way Manufactured and flexed abrasive can then be referred to as flexible abrasive, with flexibility The purpose of the abrasive is to enable the abrasive to adapt to different contours of what is to be sanded Adapt the workpiece.

Abrasives made and flexed in the manner described have basically proven themselves. However, there is a major disadvantage that the service life of the abrasive is comparatively short because there is only a single layer of abrasive grain. This layer takes advantage relatively quickly.

Various proposals have already been made to reduce the technical part of the comparatively short service life overcome.

For example, attempts have been made to address the disadvantage of the comparatively short service life of flexible abrasives to overcome the above description in that several layers of abrasive grain were applied one on top of the other. The procedure here was that, in further passes through the production plant, the surface layer explained above was applied Another layer of abrasive grain was sprinkled on, onto which a top layer of binder was applied became. In this way, two or more layers of abrasive grain could be formed. If several

If there are layers of abrasive grain, it is to be expected that the service life of the abrasive will be longer. An essential one Bach part of this well-known goal blow exists, however that the structure, which consists of several layers of abrasive grains and thermosetting binder, is comparatively hard. Accordingly, this layer structure breaks in an unpredictable manner during subsequent flexing Way on, so that there is an unpredictable grinding effect and gives a substantially uneven abrasive effect. There is also the disadvantage that abrasive grains break out can, especially if they are at break points that are formed during flexing. Finally, there is an abrasive with several layers of abrasive grain in its manufacture comparatively expensive because multiple passes through the manufacturing facility are required.

It is also known to previously applied to the substrate Binder layer not sprinkle individual abrasive grains, but so-called agglomerates, which for example are essentially spherical in shape. There are agglomerates that consist entirely of spherical corundum. There is also agglomerates with a base made of plastic, for example, in which abrasive grains are partially embedded in this way are that they protrude from the base body to the outside (DE-OS 26 08 273). It is also known, the base body to be designed as a hollow body (DE-AS 23 48 338). When using these known designs, a longer one Tool life may be expected, especially because the abrasive grains are practically in several layers on top of each other available. A disadvantage of these known designs is, however, that before use, a flexing is also required in order to achieve the required flexibility or maintain flexibility. In this flexing process

however, the previously formed structure with the agglomerates at least partially and in a non-controllable manner destroyed again, so that a total of when using the Abrasive results in an unpredictable and often uneven abrasive effect. In addition, the agglomerates break out of the binder layer holding them. Finally, such known abrasives are comparative expensive to manufacture.

It is also known (DE-GBM 19 82 299), in a preferably made of plastic flexible carrier at a distance embed abrasive bodies prefabricated from one another, with the backing thickened in the area of each abrasive body is trained. Such an abrasive can also have sufficient flexibility, such as, for example required for abrasive belts cannot be obtained. In addition, the production is comparatively expensive. The same disadvantages exist in the case of non-flexible abrasives which are also known (e.g. DE-OS 22 33 044, DE-OS 21 07 4-54, US-PS 3,471,975), "in which individual prefabricated Abrasive bodies are attached to a base body or to a base by means of special devices. These known designs also do not have the required flexibility. The production is also comparative expensive.

It is finally also known (DE-PS 17 33 14) on a flexible backing provided with an adhesive layer to sprinkle abrasive material only in certain areas, in such a way that that the abrasive material is present in predetermined locations. In this known embodiment, there is the most essential Disadvantage is that the abrasive material can only be applied in a single layer, so that the Service life of such an abrasive is comparatively short.

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There is therefore a great need for a flexible abrasive which has a comparatively long service life and yet it is simple and cheap to manufacture.

The present invention is based on a flexible abrasive with a flexible base on which a plurality of abrasive bodies are arranged in a predetermined pattern. According to the invention is one such flexible abrasive, characterized in that the abrasive body consists of one of a binder and Abrasive grain existing mass formed and glued to the substrate before the hardening of the binder.

The invention creates a flexible abrasive in which the individual abrasive bodies have abrasive grains contained in several layers on top of each other, so that a long service life of the abrasive is guaranteed. It's surprising it has been found that even when the abrasive body is arranged directly on the flexible base, a Adequate adhesion of the individual abrasive bodies to the substrate due to the adhesive effect of the binding agent could be achieved alone. In addition, an abrasive according to the invention makes the further essential The advantage achieved is that it is not necessary to flex the abrasive before it is used because the Abrasive bodies are arranged directly on the base, which in turn already has the necessary flexibility owns. By attaching the abrasive bodies in a certain arrangement on the base, free ones are created Zones or areas that ensure that the natural flexibility of the base even after the manufacturing process preserved. The finished abrasive therefore has roughly the same flexibility as the starting product used.

The production of an abrasive according to the invention can preferably take place in that a flowable or spreadable mass of binder and abrasive grain is prepared and before the hardening of the binder in the form individual abrasive body is applied to the flexible base.

In a preferred embodiment of the method, the mass prepared from binder and abrasive grain can be combined into one grid or sieve placed on the base, for example in the form of a perforated plate or the like, are pressed. The grid, sieve or the like is then removed from the base. The amount of the Abrasive body be determined by the thickness of the grid, sieve or the like.

The grid, sieve or the like can for example consist of metal or plastic.

It is particularly preferred if the flowable or spreadable mass of binder and abrasive grain, the previously prepared, has thixotropic properties, such that the mass only flows when a mechanical force or mechanical pressure is applied to them. When using a mass of binder and abrasive grain with thixotropic Properties is in particular an easier removal of the grid, sieve or the like after pressing the mentioned mass in the openings of the grid, sieve or the like possible.

In the case of certain materials for the flexible base, it can be advantageous to apply an adhesive layer beforehand.

The invention is illustrated below with reference to the drawing, for example explained.

Figure 1 is a top plan view of an embodiment of an abrasive article according to the invention.

Pig. 2 is a partial cross-sectional view of the abrasive of FIG. 1.

A flexible abrasive according to the invention can be found in In the form of sheets, ribbons and discs or the like. As an example, in Figs. 1 and 2 there is one Abrasive wheel shown.

The flexible abrasive according to FIGS. 1 and 2 has a flexible base 1 made of paper, fabric or the like. Such documents are known. On the base 1 is a plurality of consisting of binder and abrasive grain Abrasive bodies 2 arranged. The abrasive bodies can be arranged in various patterns. For example it has proven to be advantageous for an abrasive belt to place the abrasive bodies 2 in a distance from one another to arrange located rows that are at an angle of 30 ° to the direction of movement of the sanding belt.

Each abrasive body 2 consists of the mass formed from binder and abrasive grain and thus contains Abrasive grain in multiple layers on top of each other. This increases the service life of a flexible abrasive comparatively long according to the invention.

The shape of the abrasive body 2 can be different. For example, the abrasive bodies 2 can be square Shape, the shape of round, i.e. cylindrical hops or the like. The amount of abrasive grit as well their cross-sectional dimension and the distance between adjacent abrasive bodies 2 can vary depending on the conditions of use, the size of the abrasive grain, etc. When using round, i.e. cylindrical knobs For example, the diameter of the knobs can be in a range from 0.5 to 10 mm and the height of the knobs in a range from 0.1 to 5 mm, and the distance between the knobs from each other

range from 0.5 to 5 mm.

It has surprisingly been found that sufficient adhesion of the abrasive bodies 2 to the base 1 is obtained is when the mass of binder and abrasive grain that forms the abrasive bodies 2 is applied directly to the substrate 1 i.e. without the interposition of an adhesive layer. However, it may, for example, depending on the for the Flexible base material used, also in certain cases, may be useful before applying the binder and abrasive grain to apply an adhesive layer or an adhesion-improving layer to the substrate.

To produce a flexible abrasive according to the invention, a flowable or brushable one is first used Mixture made of binder and abrasive grain of the desired grain size. This mixture is then poured into the openings a grid, sieve, perforated plate or the like pressed, which was previously placed on the base. This grid, Sieve, perforated plate or the like has openings in a pattern which corresponds to the pattern in which the abrasive bodies 2 are to be arranged on the base 1. Appropriate grids, sieves, perforated sheets or the like are made of metal, plastic or a similar material.

During the application of the binder and abrasive grain Mass on the base 1 in the area of the openings of the grid, sieve, perforated plate or the like is useful proceeded so that the height of the abrasive body 2 through the thickness of the grid, sieve, perforated plate or the like is determined. In this way the process of applying the mass of binder and abrasive grain is up the base 1 is simplified and at the same time it is ensured that the abrasive bodies 2 formed all have the same

desired height.

It is particularly useful for the production of a flexible abrasive according to the invention if the Mass of binder and abrasive grain is made so that it has thixotropic properties, with thixotropic among Properties here the property is to be understood that the mass of binder and abrasive grain only flowable when exposed to mechanical stress is exposed. If the mass of binder and abrasive grain has thixotropic properties as defined above has, it no longer has the ability or the effort to flow after being applied to the base 1. Through this is the formation of the abrasive bodies 1 with the desired shape and dimensions and also the subsequent one Removal of the grid, sieve, perforated plate or the like facilitated.

For the formation of the mass of binder and abrasive grain, binders known in the field of abrasives can be used can be used, such as epoxy resin, polyurethane, urea resin, melamine resin, phenolic resin, polyester resin and inorganic binders such as water glass, phosphate binders, silicate binders, etc.

The abrasive grain is used in the required grain size. Appropriate mixing ratios of abrasive grain and binder are in the range between 0.5: 1 and 3.0 · 1> with a finer grain size of the abrasive grain using a larger mixing ratio so that the optimum in grinding performance and tool life is obtained for every grain size. The information on the mixing ratio relates to the binder and 100% solids content.

To determine the thixotropic! That can be used include alkali sulfates, alkali chlorides, alkali nitrates, bentonites, silicon dioxide and talc.

The mixture of binder and abrasive grain can continue to Auxiliaries for adjusting the viscosity are added. Suitable auxiliaries for adjusting the viscosity are e.g. light spar, cryolite, potassium tetrafluoroborate, solvents such as esters, alcohols, water, Ketones, halogenated hydrocarbons, etc. It is to be understood here that, for example, the type of used Solvent depends on the type of binder used. For a water-soluble binder like this, for example Is phenolic resin, water is of course taken as the solvent.

Further additives can also be added to the mixture of binder and abrasive grain, for example for Adjustment of the porosity or to improve the grinding performance by adding fillers with active grinding. The basic one The type of additive used depends in turn on the type of binder used. For example can, if the binder is a phenolic resin, as additives to adjust the porosity polyisocyanates or halogenated hydrocarbons are used. If an epoxy resin is used as the binder, the additive can to adjust the porosity be azodicarbonamide or ethanol. On the other hand, if the binder is a polyurethane, for example, water can be used as an additive to adjust the porosity. As grinding-active fillers, the common fillers in the abrasives industry are used, e.g. cryolite, potassium tetrafluoroborate, potassium sulfate, Pyrite, halogenated organic compounds and sulfur-containing organic compounds. It is also possible through microencapsulated substances, e.g. microencapsulated oil, to achieve a porosity that has the abrasive properties

and the ability to attack during the grinding process has a very strong influence, and at the same time it is more active in grinding in this way Filler can be added.

In certain cases it can be advantageous to add a wetting agent to the mixture of binder and abrasive grain. i.e. an agent which is used when applying the mass of binder and abrasive grain to the flexible base ensures that the mass completely wets the material of the base. Suitable wetting agents are, for example

Polyethylene glycols, sulfurized castor oil, fatty alcohol sulf onates or silicone oils.

In some cases, depending on the particular material used for the flexible base is used, it may be expedient to add an adhesion promoter to the mass of binder and abrasive grain. to suitable adhesion promoters include polyamino amide and saturated and unsaturated polyesters.

In order to use the individual abrasive bodies during certain grinding operations The entire abrasive body can be subjected to high mechanical loads to achieve further improvements provided with a coating of a binder. The coating binder then covers both the individual Abrasive bodies as well as the zones in between. Thus the flexibility of the finished abrasive on a backing is not adversely affected, this coating should only be applied in the appropriate amount, or · that Coating binders themselves could be elastic (e.g. polyurethane).

With regard to the flow behavior of the mass of binder and abrasive grain with additives, it should be noted that it for the theological behavior and good workability

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What is important to the mass is that the flow limit, the thixotropy and the viscosity have certain values. These values are achieved through a suitable selection of the type and the Grain size, i.e. the fineness of grind of the fillers, thixotropic agents and solvents. Of course it depends Flow behavior of the mass also depends on the type of binder used, i.e. the resin used, and on the Grain size of the abrasive grain.

The invention is described in more detail below with the aid of examples.

example 1

A mass of the following composition was formed:

Epoxy resin 100 parts

Hardener (amine) 13 parts

Abrasive grain as corundum one

Particle size of about 80 / u. 226 parts

Talc 10 parts

Methyl ethyl ketone 26 parts

Iron oxide red 3 parts

First, the binder and the abrasive grain are mixed together in a mixer until they are homogeneous Mixture emerged. Then the additives, namely the hardening agent, the thixotropic agent, the viscosity adjustment agent, which at the same time serves as a solvent for the epoxy resin, as well as the colorant added and mixed in well. The mixture is then immediately ready for use and can, for example, in the manner described above using a grid, Sieves or the like are applied to a flexible base.

Example 2

Using the procedure according to Example 1, a mass of binder and abrasive grain with the following composition was obtained manufactured"

Phenolic resin (72%, ie with 72 % pesticide content) 100 parts

Silicon carbide with a particle size of approx. 200 μ 160 parts

Potassium sulfate 100 parts

Bentonite Colclay 3 parts

Water 29 parts

Example $

According to the procedure given in Example 1, a mass was produced from the following composition:

Melamine resin 100 parts

Hardener 1 part

Corundum of one particle size

of approx. 80 / x 260 parts

Particle size cryolite.

of approx. 30 μ 50 parts

Water ^{22 parts}

The specified parts are always parts by weight.

It should also be noted that the prepared mixture or the prepared mass may also

can be left for a few days until it is processed is, at least in the case of the use of one-component binders.

With regard to the abrasive grain, it should be said that the range of applicable grain sizes or particle sizes is in the range from 10 to 2000/1 . The particular grain size that is used in each case depends on the intended use

With regard to the grid, sieve or the like, it should also be noted that, for example, such grid, sieves or the like can be used in planar form.

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Claims (26)

Claims Flexible abrasive with a flexible base on which a plurality of abrasive bodies in one predetermined pattern is arranged, characterized in that the abrasive body (2) consists of one of a binder and abrasive grain are formed and adhered to the substrate before the hardening of the binder. 2. Abrasive according to claim 1, characterized in that the mass forming the abrasive body is a thixotropic agent contains. 3- abrasive according to claim 2, characterized in that that the thixotropic agent is an alkali metal sulfate, an alkali metal chloride, an alkali metal nitrate, a bentonite, silicon dioxide or talc. 4. Abrasive according to one of claims 1 to 3i characterized in that the binder is an organic binder. 5. Abrasive according to one of claims 1 to 3, characterized in that the binder is an inorganic one Binder is. 6. Abrasive according to one of claims 1 to 5, characterized in that the mass forming the abrasive bodies is an auxiliary for adjusting the viscosity is admitted. 7- abrasive according to claim 6, characterized in that the adjuvants for adjustment the viscosity of light spar, cryolite, potassium tetrafluoroborate, potassium sulfate, pyrite, sulfur-containing organic compounds, Microencapsulated substances and oils or solvents are, for example esters, alcohols, water, ketones, halogenated Hydrocarbons etc. 8. Abrasive according to claim 7? characterized in that the auxiliaries for adjusting the viscosity are at the same time grinding-active fillers. 9. Abrasive according to one of claims 1 to 8, characterized in that the abrasive body forming mass an additive to adjust the porosity is added. 10. Abrasive according to claim 9, characterized in that when using a modified phenolic resin for the binder, the additive for Adjustment of the porosity a polyisocyanate or a halogenated one Is hydrocarbon. 11. Abrasive according to claim 9,
characterized in that when an epoxy resin is used as the binder, the additive for adjusting the porosity is an azodicarbonamide or ethanol. 12. Abrasive according to claim 9, characterized in that when using polyurethane as the binder, the additive for adjusting the porosity is water. 13. Abrasive according to claim 9, characterized in that the additive for setting the porosity is a microencapsulated substance or a microencapsulated one oil is. 14. Abrasive according to one of claims 1 to 13, characterized in that a wetting agent is added to the mass forming the abrasive bodies. 15. Abrasive according to claim 14, characterized in that the wetting agent is polyethylene glycol, It sulphurizes castor oil, an I fatty alcohol sulfonate or a Silicone oil is used. 16. Abrasive according to one of claims 1 to 15, characterized in that the abrasive body an adhesion promoter is added to the forming mass. 17. Abrasive according to claim 16, characterized in that the adhesion promoter is a polyaminoamide, is a saturated polyester or an unsaturated polyester. 18. Abrasive according to one of claims 1 to 17, characterized in that the flexible base (1) is provided with an adhesive layer or an adhesion-improving layer ;. 19. Abrasive according to one of claims 1 to 18, characterized in that it is additionally provided with a coating which does not impair the flexibility. 20. Abrasive according to one of claims 1 to 19, characterized in that the binder and abrasive grain in a ratio in the range from 0.5: 1 to 3.0: are present. 21. Abrasive according to one of claims 1 to 20, characterized in that the abrasive bodies have a cylindrical or angular shape. 22. Abrasive according to claim 21, characterized in that cylindrical abrasives have a diameter in the range from 0.5 to 10 mm, have a height in the range from 0.1 to 5 mm and the flexible base (1) are attached at a distance in the range of 0.5 to 5 mm. 23. Abrasive according to one of claims 1 to 22, characterized in that the abrasive grain is present in a particle size in the range from 10 to 2,000 JU . 24. Abrasive according to one of claims 1 to 23, characterized in that a dye is added to the mass forming the abrasive bodies. 25. Abrasive according to one of claims 1 to 24, characterized in that it has approximately the same flexibility as the original pad. 26. Method of making a flexible abrasive article according to one or more of the preceding claims, characterized in that a flowable mass of binding agent and abrasive grain prepared and before the hardening of the binder in the form of individual abrasive particles on the flexible Pad is applied. 2.7 method according to claim 2 6, characterized in that the flowable mass for application in the form of individual abrasive bodies on the flexible base through the openings of a grid, sieve or the like is pressed, which is placed on the base.