EP0193455B1 - Rough article, process for its production and its use in treating surfaces and textiles - Google Patents

Description

The invention relates to a rough product, finding particularly advantageous applications in the treatment of hard surfaces, in particular for lapping and polishing of metallic or mineral surfaces, as well as in the surface treatment of textiles.

Mechanical abrasion of surfaces, particularly of metal, very often uses products intended for lapping, polishing, emerying or smoothing. In the rest of the description of the invention, we will speak of abrasive products without distinguishing between abrasion, polishing and sanding, knowing that polishing and emery-making are part of abrasion in its broad sense. The action of these products is intended to obtain a uniform surface by removing the surface irregularities due to previous treatments. It is therefore generally a material removal action (dimensioning) and / or a finishing action. Products with bound or applied abrasives are compounds, comprising a support on which are fixed with a binder particles of hard materials. During the mechanical treatment, the abrasive support is set in motion, generally in rotation in contact with the surface to be treated, and it is the particles fixed on the support which by friction remove the material. The material constituting the abrasive particles and the size of said particles are chosen according to the type of surface to be treated and the desired degree of finish. One of the disadvantages of these abrasive products is their rapidity of wear, which is due to the heating and tearing of the abrasive particles during the treatment.

There is a second lapping, polishing technique, known as free abrasive, in which polishing agents in liquid form are added to a support. These polishing agents are essentially mixtures of greases, oils and alcohols which act as lubricants and coolants, in which are carefully calibrated grains of various abrasives such as diamond, alumina, carbide or metal oxides, etc. These agents are generally introduced continuously, drop by drop, throughout the work because the movement of the abrasive support, for example its rotation at high speed, displaces the polishing agent outside the treatment zone properly said, under the action of centrifugal force. It is therefore imperative to constantly renew the polishing agent. This is another drawback of these methods. The case of diamond paste is similar because it requires the constant supply of a diluent during work, which is itself centrifuged with the abrasive.

Now we have found, and this is what is the subject of the invention, a rough product which overcomes the drawbacks observed. In a manner which is known in food graters, in particular in patent FR-A-1 485 475, this rough product is made of plastic and has holes whose contours are in relief relative to the surface. According to the invention, the rough product consists of a film whose thickness is of the order of ten to a few hundred micrometers and which has been perforated, the contours of the perforations forming deformable craters. The product of the invention serves as a support for a polishing agent: there can no longer be entrainment as on a smooth surface, or removal of the particles, as with the usual methods. There is simply wear of the raised parts, but it has been found that, surprisingly, the wear of the edges of the perforations made in the plastic film is very slow, compared for example to that observed by tearing off the particles on a bonded abrasive.

Preferably, use is made of a plastic film having sufficient mechanical and strength characteristics, in particular a polyester, polyamide, polyimide or polypropylene film. The thicknesses of 23, 36, 50, 75, 100, 125 and 175 µm are particularly suitable.

Advantageously, the perforations are carried out using needles according to a technique which is similar to that used in the textile industry and called needle punching. In this tying technique, specific to the manufacture of nonwovens, the fibers are intermingled by the action of a large number of needles which pass through a fiber mat in a reciprocating movement. The mattress, driven by a conveyor, passes between the plates of the needling machine. The resistance of the nonwoven increases with the density of the needling stitches. Thus, according to the same technique, it is easy to make in a plastic film perforations of a given conformation and size, functions of the type of needles, and in a given density, function of the population of needles and the number of strokes during the needling. By examining a perforation under the microscope, we note that the plastic material is pushed back at the point of impact of the needle, in the form of a kind of crater whose edges depend on the configuration of the section of the needle, which is preferably triangular. These are the edges of the craters which, applied to the surface to be treated, in cooperation with the abrasive grains act as active elements. The amount of plastic material constituting the edges of the crater and the size of the crater depend on the section of the needle and generally on the depth of penetration of the needle into the film. The larger the needle and / or the greater the penetration depth, the larger the perforations. The dimensions of these perforations can therefore be varied with relative precision by appropriate adjustment of the needling equipment. On the other hand, the number of perforations is conditioned on the one hand by the density of implantation of the needle support board, generally from 1,800 to 15,000 needles per linear meter, and secondly by the number of times the needle support board is applied to the film during its running (the number of strokes per minute) and last leaves by the speed of advance of the film.

When adding a polishing agent, it is found, unexpectedly that, contrary to what happens with the usual abrasive products, the polishing agent is not removed during the displacement of the product according to the invention, and that it is therefore no longer necessary to feed it as often and in such a large quantity. We can try to explain this phenomenon by considering the behavior of the perforations during the movement of the abrasive product during polishing. Take the case of an abrasive product cut in the form of a circular washer which is fixed on a mobile support in rotation. During polishing, the support and therefore the abrasive product rotate at high speed. The piece whose surface is to be polished is applied to the abrasive surface of the product, while the polishing agent drops, drop by drop, onto said abrasive product. We have seen that for a usual abrasive product, the polishing agent is driven by centrifugal force towards the outside of the washer. For the product according to the invention, the perforations will constitute as many obstacles and act as suction cups to retain the polishing agent: they are compressed and deform during the application of the part to be treated, then they return to their initial shape. In this movement they release and then somehow suck the liquid agent nearby, thus causing a continuous movement of mixing and self-cleaning of the abrasive particles.

While for the treatment of hard surfaces, the rough product according to the invention is preferably used in combination with an abrasive, it has been discovered that the rough product finds a particularly advantageous application, used alone, in the treatment of surfaces textiles, in particular the scraping of sueded fabrics, or the drawing of hairs intended to increase the bulkiness of a fabric.

• - la figure 1 est une vue schématique, en coupe transversale, d'un film conforme à l'invention, au niveau de la perforation,
• - la figure 2 montre partiellement une aiguille utilisée dans le procédé de fabrication conforme à l'invention,
• - la figure 3 est une photographie prise au microscope (grossissement 14) d'un film perforé,
• - la figure 4 est une vue schématique, en coupe transversale, du film de la figure 1, dans son utilisation comme support d'abrasif.

Other advantages of the invention will emerge from the following description made with reference to the accompanying drawings in which:

• FIG. 1 is a schematic view, in cross section, of a film according to the invention, at the level of the perforation,
• FIG. 2 partially shows a needle used in the manufacturing process according to the invention,
• FIG. 3 is a photograph taken under the microscope (magnification 14) of a perforated film,
• - Figure 4 is a schematic view, in cross section, of the film of Figure 1, in its use as an abrasive support.

Film 1 (figs. 1 and 3) is a mono-stretch polyester film - TERPHANE brand - 6/100 millimeter thick and weighing 70 grams per square meter. It passes through a needling material, textile type, composed of a needle board animated by an alternating raising and lowering movement, two perforated plates, a food apron which transports the film and two exit cylinders synchronized with the movement of the needle board, so that the film is stationary during the downward movement of the board and advances a certain distance during the lifting movement, when the film is no longer crossed by the needles . The film is introduced between the two plates which hold it during the action of the needles. The needle board descends until the needles are in contact with the film and pass through it. The equipment includes a mechanism for adjusting the stroke, that is to say the movement of the needles, generally between 50 and 75 millimeters. In the binding of textile sheets, this setting makes it possible to vary the depth of penetration of the needle into the sheet. In the present case of perforation of a plastic film, to obtain the rough product according to the invention, the impact stroke is adjusted so that the penetration of the needle into the film is very short of the order of or a few millimeters. In any event, only the smooth part 6 of the needle 2 should enter the film (fig. 2), so that the material repelled by the needle 2 on impact finds itself entirely on the same side. of the film 1 and forms a crater 3. In fact with a normal adjustment, the part of the needle having barbs 4 for hanging the fibers of the textile web would penetrate the film and, during lifting, would cause part of the material on the other side of the film. Thus, as illustrated in FIG. 1, during the penetration of the needle 2 into the film 1, the material of the film 1 is torn and pushed outwards by the needle 2 in the form of a crater 3 whose the walls are more or less regular. The photograph (fig. 3) clearly shows all the craters formed by the impact of the needles, and whose dimensions are relatively homogeneous and depend on the precision of the adjustment of the needling equipment. In the example illustrated in FIG. 3, there were 150 needle strokes per square centimeter with a stroke of stroke set at 1 millimeter. These needles were of the SINGER 15 x 18 x 36 x 3.5 BL type.

The film thus perforated was then tested on a polisher of the MECAPOL type, with a rotation of 300 revolutions per minute, six samples of metal with a diameter of 30 millimeters being applied to the film in the form of a disc at a pressure of 7 kg. A 6 micron diamond aerosol was used as the polishing agent. An average metal removal of 9.66 grams per sample was found after 4 minutes of testing, 8.66 grams after a second 4-minute operation, and 8.16 grams after a third 4-minute operation.

Furthermore, it has been found that the polishing agent is preferably located after the film has passed under the metal samples, in the cavities formed by the perforations. On the other hand, the polishing waste preferably collects on the free surface between the craters which allows their elimination by washing.

In order for the abrasive product according to the invention to fulfill its role properly, the craters 3 must be able to react under the pressure of the material to be treated and behave like micro-pumps setting in motion the polishing agent. To illustrate this need, the film was fixed on the rotating support of the test equipment using an adhesive, allowing it to rise inside the craters of the film: the craters being blocked by the adhesive, they no longer fulfill their function of pump and reservoir of polishing agent and the film largely loses its abrasion properties.

This use of the rough support of the invention is illustrated in FIG. 4 which shows the film 1 bonded by means of an adhesive 7 to a disc 8 rotatably mounted on a shaft 9 driven in the direction of the arrow 10.

The workpiece 11 is supported and driven in the direction of the arrow 12. The craters 3 contain the abrasive particles and the polishing agent 13 and the waste released on the surface of the workpiece 11 collects in the free spaces 14 between the craters.

For applications in the mechanical finishing of fabrics, the rough film according to the invention has also proved to be very advantageous. A typical example of a polyester film used has the following characteristics: thickness 23 µm; specific mass: 1.39 g / m ³ ; breaking strength: 19 daN / mm2 in the long direction and in the cross direction; elongation at break: 120% in the long direction and 80% in the cross direction; modulus of elasticity at 0.5% elongation: 450 daN / mm ² in the long direction and in the cross direction. During the tests, it appeared that the desired perforation density of 20 to 150 perforations per cm ² , preferably 40 to 50 perforations, the distribution (or pattern) of the perforations being of random type to avoid any possibility of lineage on the parts treat.

Scraping tests on fabrics were carried out to try to evaluate on the one hand the behavior of the perforated film, and on the other hand, according to the type of textile subjected to this friction test, what were the modifications of aspect obtained.

It emerges from these tests that compared to a very fine abrasive (such as fine sandpaper), generally used in textile control laboratories to simulate the destructive abrasion of a fabric, the perforated film is far less active. Thus for a cotton taffeta fabric of 60 threads per cm in warp, and 28 strokes per cm in weft, and with a weight per m ² of 120 g, it was observed that with the perforated film at 45 holes / cm ² , after 900 revolutions and under a pressure of 250 g, the abrasion was very regular and there was no perforation.

On the other hand, with a sandpaper (ref. P. 1200) after 10 turns and under a pressure of 250 g, there were already three perforations.

The degradation is therefore much slower with the perforated film.

The observation times are therefore longer and allow for more precise examination tests.

The perforated film demonstrates a less rapid attack against the finest commercial abrasives, opening up finishing possibilities for very interesting delicate suede.

In another series of tests, we looked at the use of the perforated film to increase the bulk of a fabric.

The fabrics for scarf are of the twill or satin type, so as to present on one side very large fiber floats.

The use of the rough film of the invention has given very good results in terms of drawing hairs on fabrics intended for this use. Thus for a scarf fabric (100% acrylic material, 250 g / m ² , 8 threads per cm in warp, 12 strokes per cm in the weft, twill weave of 2 dregs 2), we observed that the average length of the strands pulled was 20 mm. In addition, the abundance was significant and the loss by breakage of strands very low.

Claims (9)

1. Rough product, in plastics material presenting perforations of which the outlines are raised with respect to the surface, characterized in that it is constituted of a film (1) of which the thickness is around between 10 µm and 175 µm, and which has been perforated, the outlines of the perforations (5) forming deformable raised craters (3).

2. Rough product according to claim 1, characterized in that the film is made from polyester, polyamide, polyimide or polypropylene.

3. Rough product according to claim 2, characterized in that the film is a mono-drawn polyester film of thickness less than one tenth of a millimeter.

4. Method for producing a rough product, in plastics material, presenting perforations of which the outlines are raised with respect to the surface, characterized in that a film (1) is used, the thickness of which is of the order of between one tenth and a few hundreths of micrometers, said film being perforated with needles penetrating into the film and pushing the needle-traversed material in such a way that the outlines (3) of the perforations (5) form deformable craters raised with respect to the surface of the film.

5. Method according to claim 4, characterized in that the needles (2) of triangular cross-section are used.

6. Utilization of the rough product according to any one of claims 1 to 3, as abrasive base for the treatment of a hard surface.

7. Utilization according to claim 6, characterized in that said treatment consists in grinding, polishing, sanding or smoothing said surface.

8. Utilization of the rough product according to any one of claims 1 to 3, for the treatment of a textile surface.

9. Utilization according to any one of claims 6 to 8, characterized in that the film used has a mean perforation density of 20 to 150 per cm² and preferably 40 to 50 per cm^2.

Images