CN114055354A

CN114055354A - Method for treating abrasive material and abrasive material

Info

Publication number: CN114055354A
Application number: CN202110864035.XA
Authority: CN
Inventors: J·胡贝尔
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2020-07-29
Filing date: 2021-07-29
Publication date: 2022-02-18
Also published as: DE102020209520A1

Abstract

The invention relates to a method for treating an abrasive (10), in particular a coated abrasive (10), comprising the following method steps: providing an abrasive material (10), coating the abrasive material (10) with a detackifying agent, drying the detackifying agent on the abrasive material (10), and locally-resolved melting of the detackifying agent by irradiation with light (38), in particular laser light, to produce visually structured regions (24, 24a, 24 b). Furthermore, a correspondingly treated abrasive (10) is proposed.

Description

Method for treating abrasive material and abrasive material

Technical Field

The present invention relates to a method for treating an abrasive to produce visually structured regions. Furthermore, the invention relates to a correspondingly treated abrasive.

Background

Methods for making abrasives having visually structured regions are known. Typically, the colorant is applied to the abrasive substrate in a structured manner. For the structured application of the colorants, use is made in particular of stamps, embossing rollers or roller-to-roller processes (roller-zu-roller-Verfahren), such as the embossing process (Hochdruckverfahren) or the gravure process (tiefddruckverfahren).

Furthermore, methods for treating abrasives are known, for example, from US 5766277B and US 2768886B, in which a release agent dispersion is applied at least to the surface of the abrasive provided for grinding in order to produce the cover layer, wherein the release agent dispersion has at least one antiblocking agent.

Disclosure of Invention

A method for treating abrasives, in particular coated abrasives, is proposed. The method of the invention comprises the following method steps: providing an abrasive; coating the abrasive with an anti-tacking agent; drying, in particular, the release agent on the abrasive; in a locally resolved manner by irradiation with light, in particular laser light

The release agent is melted to create visually structured areas.

"abrasives" are used for grinding or lapping of workpieces, in which material of the workpiece is mechanically removed from the surface of the workpiece in the form of chips. The abrasive is in particular a coated abrasive (e.g. with paper and/or film as an abrasive backing) or a composite abrasive comprising a foam and a superstrate (e.g. film or fabric) or a foam abrasive. Furthermore, alternative abrasives are also conceivable in principle, for example bonded abrasives, which are in particular related to typical synthetic resin-bonded cutting and roughing disks. In one embodiment, the abrasive is implemented as sandpaper.

The abrasive material comprises a particularly flexible abrasive backing having at least one layer. Particularly flexible abrasive substrates impart particular characteristics to the abrasive in terms of adhesion, strain, crack and tensile strength, flexibility and stability. In particular, the abrasive substrate can comprise, in one or more layers, paper, cardboard, vulcanized fibre, foam, plastic, textile, in particular woven (Gewebe), knitted (Gewirke), crocheted (Gestricke), braided (Geflecht), non-woven or a combination of these materials, in particular a combination of paper and woven. In the case of coated abrasives, the abrasive particles are fixed to the abrasive substrate by means of a binder (often referred to as a base binder). The abrasive particles are at least pre-fixed, in particular fixed, on the abrasive substrate, in particular in a desired position and/or distribution, by means of a binder. Suitable binders for securing abrasive particles to an abrasive backing are known to those skilled in the art from the prior art. For example, such adhesives in the prior art are solvent-based adhesive materials, such as polychloroprene. In addition to the binder as a base binder, it is also possible to use a further so-called cover binder, which is applied in particular in layers over the abrasive grains fixed to the abrasive substrate by means of the base binder. Here, the cover adhesive fixedly connects the abrasive grains to each other and to the abrasive backing. In particular, suitable covering adhesives are sufficiently known to the person skilled in the art from the prior art. In particular, synthetic resins such as phenol resins, epoxy resins, urea resins, melamine resins and polyester resins are suitable as the covering adhesive. In addition, additional additives ("grinding additives") can be provided to impart specific characteristics to the abrasive article. Such additives are well known to those skilled in the art.

The abrasive has a surface provided for grinding, i.e. an abrasive surface, in particular on that side of the abrasive on which the abrasive grains are fixed and, if appropriate, a covering binder and/or further additives. The grinding surface of the grinding material is moved over the workpiece to be machined during the grinding process, so that a grinding action is produced by means of the abrasive grains arranged on the grinding surface. In principle, the abrasive can be present in different finished shapes, for example as a grinding disk or grinding belt, as a bow, roller, strip or (for example during manufacture) also as an abrasive product belt.

"anti-sticking agent" is understood to mean a medium which prevents or reduces the accumulation of chips which accumulate during the grinding process. The anti-sticking agent serves to prevent or reduce chip deposits in the interstices between adjacent abrasive grains, which chip deposits can cause, in particular, clogging or adulteration of the abrasive surface of the abrasive. In particular, anti-blocking agents are used to prevent or reduce this effect: in the case of this effect, the heat generated during grinding causes the chips to sinter, bond or fuse and melt on the grinding surface of the abrasive and this can also cause clogging or adulteration of the grinding surface of the abrasive (as is often the case, for example, when plastics, plastic paints or the like are to be ground). Advantageously, this improves the cutting ability of the abrasive and in particular improves the durability (service life). This uses the anti-sticking agent as a lubricant between the abrasive and the surface of the workpiece to be machined during the grinding process. In one embodiment of the method, the detackifier is selected to be a stearate. In particular, in the literature on abrasives, the anti-sticking agent is commonly referred to as a "stearate," although the anti-sticking agent can include materials that help prevent chip build-up. For example, the detackifier can have as a constituent a metal salt of a fatty acid (e.g., zinc stearate or calcium stearate), a phosphate ester salt (e.g., potassium behenyl phosphate), a phosphate ester, a urea formaldehyde resin, a wax, a mineral oil, a cross-linked silane, a cross-linked silicone, a fluorochemical, and/or combinations thereof. Typically, such detackifiers are made from fats containing a mixture of fatty acids. For example, the detackifier (referred to herein as "stearate") can also contain calcium salts of other fatty acids, such as palmitates, myristates, or laurates. It is noted that such anti-blocking agents are known to the person skilled in the art, for example from US 5766277B.

By "coating the abrasive with a detackifier" is understood that the detackifier is applied to the surface of the abrasive. This can be achieved, for example, by means of a release agent dispersion which is applied to the surface of the abrasive. In this case, in particular the finest particles of the antiblocking agent are "suspended" (schweben) in the dispersion medium of the release agent dispersion. The release agent dispersion can be applied to the surface of the abrasive material by knife coating, roll coating, printing, brush coating, or the like. Drying of the release agent on the abrasive can be carried out, for example, by evaporation of the dispersion medium, so that particles of the release agent remain on the surface of the abrasive. The regions formed on the surface by the particles appear white due to refraction of light, wherein the abrasive has a visually non-uniform appearance.

In order to achieve a surface structure of uniform color, abrasives coated with antiblocking agents are typically heated according to the prior art (e.g. US 5766277B) over the entire surface, so that the particles melt and thus a transparent film is produced on the surface of the abrasive. Instead, it is proposed in DE102018220672 a1 to add, instead of a melting process, a film former to a mold release agent dispersion, which film former enables transparency to be achieved even without such an energy-intensive melting process.

According to the invention, the entire melting is replaced by a locally resolved melting of the antiblocking agent. By "locally resolved melting of the release agent" is understood that the release agent is heated locally (i.e., spatially limited) by targeted irradiation with light, in particular laser light, in such a way that the release agent melts at the irradiated site or in a narrow spatial environment, for this purpose on the abrasive surface, and forms a locally continuous transparent film. "spatially resolved" means that, for example, a release agent applied to the abrasive substrate over the entire surface can be melted in a spatially arbitrary manner, i.e., at different locations, with correspondingly melted and unmelted regions being produced on the abrasive. Thus, location resolution involves at least two-dimensional locations on the abrasive. It is thus possible, instead of a continuous, uniform coating, to produce, on the surface of the abrasive, targeted visually different regions which appear visually transparent (or in some cases also translucent) up to slightly visually opaque, in particular with different optical refractive indices. In this manner, the "visually structured regions" of the present invention can be achieved on the surface of the abrasive.

The visually structured regions include: the regions of the abrasive surface where the detackifier has melted and thus appeared visually clear such that the abrasive surface is transparent to light; and the areas of the abrasive surface where the detackifier did not melt and thus appeared opaque to white or milky white. In particular, visually structured regions that can be produced in a controlled manner (and in particular also reproducibly) in this way can be regarded as patterns or images that can be produced in a controlled manner (and in particular also reproducibly) on the abrasive surface.

In one embodiment of the method, a continuously varying pattern of visually structured regions is applied to the abrasive. The proposed invention enables the production of a continuously varying pattern of visually structured areas without making a sample or a negative for the pattern, similar to conventional printers known in offices. In this manner, the altered pattern or image can be smoothly applied to the abrasive. Such a pattern can in particular be an image such as a manufacturer logo or the like. Alternatively or additionally, the pattern can purposefully (and often inevitably) mask non-uniformities on the abrasive surface, such as non-uniformities in the abrasive coating. Thus, a visually uniform abrasive can be achieved.

In one embodiment of the method, the visually structured region encodes information, in particular information about the abrasive. For example, such information can relate to the manufacturer (e.g., in the form of a logo, name), the particle size of the abrasive, the material of the abrasive, the serial number of the abrasive, or the like. It should be noted that the encoded information can also be applied in a continuously varying fashion to different regions of the abrasive material by the method of the present invention. For example, in implementations of the method of the present invention implemented as a roller-to-roller method, the feed meters of the abrasive article belt are provided with successive meter specifications. It is further contemplated that the continuously numbered abrasive raw material is produced on the abrasive article belt by location, which produces each of the continuously numbered abrasives after the abrasive article belt is cut. Furthermore, it is conceivable to release the regions to be cut out later by stamping or laser cutting in a targeted manner, so that no energy is wasted here for melting the antiblocking agent.

In one embodiment of the method, the method step of the locally resolved melting is carried out after, in particular immediately after, the method step of drying the antiblocking agent, in particular the applied release agent dispersion. "directly after" is to be understood as meaning that no further process steps or processing steps are carried out between the drying process step and the locally resolved melting process step.

In one embodiment of the method, the method is carried out, in particular, within a roller-to-roller method, followed, in particular followed, by a method for producing an abrasive material. In this way, the residual heat of the grinding material can be utilized in the method step of the locally resolved melting of the anti-adhesive agent. Thus, the energy input that has to be applied (i.e. incident) in order to melt the antiblocking agent can be lower, so that energy is saved. Furthermore, the method can be implemented as a roller-to-roller method. The method according to the invention can thus be integrated into an existing process chain of a production method and a corresponding process environment (Prozesslandschaft), for example into an existing production plant, without additional, in particular costly, machine or structural modifications in the process chain and/or in the process environment.

The use of light, in particular laser, for the locally resolved melting shows the possibility of a particularly effective, highly precise, locally resolved melting of the antiblocking agent. For example, the spatially resolved illumination by means of directed light can be achieved using x-y laser scanners, which are known, for example, from laser printing, lidar, etc. applications. Alternatively, DLP chips (known from applications such as light projectors) can be used or light shields can also be used in order to achieve a spatially resolved illumination. For example, as the laser, a solid laser or an infrared laser diode is suitable.

In one embodiment of the method, the abrasive material is cut and/or a hole pattern is produced in the abrasive material by means of irradiation with light, in particular laser light. In this way, the components necessary for producing the abrasive material, in particular the light source for melting the release agent and for cutting or perforating the abrasive material, can be reduced. No additional equipment is required that cuts the abrasive into its target shape, such as a grinding wheel that includes holes.

The invention also relates to an abrasive material made by the method of the invention.

Drawings

In the following description, the invention is explained in more detail with reference to embodiments shown in the drawings. The figures, description and claims contain many combinations of features. The person skilled in the art can also expediently view these features individually and combine them into meaningful further combinations. Like reference symbols in the various drawings indicate like elements.

In the drawings:

FIG. 1 shows a schematic cross-sectional view of an abrasive material having abrasive particles of the present invention;

FIG. 2 shows a top view of one embodiment of the abrasive of the present invention;

FIG. 3 illustrates a method flow diagram for illustrating a method for making an abrasive material of the present invention;

fig. 4 shows an exemplary fabrication structure for implementing the method of the present invention.

Detailed Description

FIG. 1 illustrates, in schematic cross-section, a portion of an exemplary embodiment of an abrasive material 10 having abrasive particles 12 treated in accordance with the present invention. Abrasive 10 is, in the embodiment shown, a coated abrasive 10 having an abrasive backing 14 made of paper. An abrasive backing 14 made of paper is used as the flexible backing for the abrasive particles 12. The abrasive particles 12 are fastened to the abrasive substrate 14 by means of a binder 16, in particular a base binder 18, which is realized here, for example, as a thermoplastic polyurethane binder. The layer of base binder 18 and abrasive grains 12 is additionally coated with a covering binder, not shown in detail here, which is made in particular of a phenolic resin. A layer 22 of a release agent is applied to the surface 20 of the abrasive. Abrasive 10 has a visually structured region 24 on its surface 20 comprising a first region 24a of melted release agent and a second region 24b of unmelted release agent (not shown in detail herein; but see FIG. 2)

Fig. 2 shows a top view of abrasive material 10 of the present invention, as produced by the method for processing abrasive material 10 having visually structured regions 24 of the present invention (see fig. 3). As already explained with respect to fig. 1, abrasive 10 has visually structured regions 24 comprising first regions 24a having melted release agent and second regions 24b having unmelted release agent. In plan view, the first region 24a appears in the color of the surface of the abrasive 10 (backing) due to the transparent property of the melted releasing agent, and the second region 24b appears opaque to white or milky white. Visually structured areas 24 reproduce pattern 26 or an image when first area 24a and second area 24b are viewed together. Visually structured abrasive regions 24 also encode information about abrasive 10, presented as a company logo ("Sia adhesives" on top) and the grit size of abrasive 10 ("80" on bottom). In addition, in the case of an image analysis evaluation method, pattern 26 is oriented such that visually structured regions 24 mask non-uniformities on the surface of abrasive 10.

A method flow diagram illustrating an embodiment of a method 100 of the present invention for making abrasive material 10 with structured abrasive regions 22 is reflected in fig. 3. Fig. 4 shows a fabricated structure 30 that matches this method. Abrasive material 10 is provided in a first method step 102. In the exemplary roller-to-roller method illustrated in fig. 4, this is accomplished by advancing the abrasive article belt 32 in the manufacturing configuration 30 such that the abrasive article belt 32 passes over the diverting rollers 42 into the area shown here responsible for carrying out the method. Here, the method for processing the abrasive material 10 of the present invention immediately follows the method for manufacturing the abrasive material 10. In method step 104, the abrasive 10, in particular the abrasive article tape 32, is coated with a release agent in the form of an application layer 22. Here, the release agent, here in the form of a stearate, is sprayed in the form of a release agent dispersion by means of a nozzle 34 onto the surface of the abrasive article belt 32 and is immediately heated by means of a heat radiator 36 in order to evaporate the dispersing agent. The unmelted release agent remains on the surface of the abrasive article belt 32. In a method step 106, the light 38 is used for the purpose of spatial resolution by irradiation

In such a way that the previously applied anti-adhesive agent is melted. Here, the visually structured regions 24 of the invention are produced (see fig. 2). In fig. 4, light 38 is generated as laser light by a laser 40. In method step 108, abrasive material 10 is also trimmed by irradiation (i.e., cut into a circular disk as shown in FIG. 2) using light 38 (here a laser light) and a pattern of holes 28 is created in abrasive material 10. Here, each cut abrasive 10 can also remain temporarily in the abrasive article belt 32, for example, by not cutting the abrasive 10 all around, but by still retaining a small number of thin carrier tabs that hold the abrasive 10.

Claims

1. Method for treating an abrasive (10), in particular a coated abrasive (10), comprising the following method steps:

-providing an abrasive material (10),

-coating the abrasive material (10) with a detackifying agent,

-drying the release agent on the abrasive material (10),

-melting the anti-adhesive agent with local resolution by irradiation with light (38), in particular laser light, to produce visually structured regions (24, 24a, 24 b).

2. The method of claim 1, wherein the detackifier is a stearate.

3. The method according to any one of the preceding claims, wherein the visually structured areas (24, 24a, 24b) encode information.

4. The method according to any of the preceding claims, wherein the visually structured regions (24, 24a, 24b) mask non-uniformities on the surface (20) of the abrasive material (10).

5. The method according to any one of the preceding claims, wherein the abrasive material (10) is cut and/or a pattern of holes (28) is created in the abrasive material (10) by means of irradiation with light (38).

6. The method according to one of the preceding claims, wherein the melted method step is carried out after, in particular immediately after, the dried method step.

7. Method according to any one of the preceding claims, wherein the method is carried out in particular within a roller-to-roller method following, in particular immediately following, a method for producing the abrasive material (10).

8. Method according to any of the preceding claims, wherein the abrasive (10) is realized as a coated abrasive, a composite abrasive with a foam material and an upper layer material, or a foam abrasive.

9. Abrasive material (10) treated according to the method of any one of the preceding claims.