DE29521320U1 - Washing roller for mechanical cleaning, especially of scratch-sensitive surfaces of motor vehicles - Google Patents

Description

The invention deals with the problem of mechanically cleaning sensitive surfaces, especially scratch-sensitive painted but also unpainted surfaces, for example painted vehicles in automatic car washes or unpainted panels made of artificial glass such as noise barriers made of acrylic glass. In particular, the invention relates to a brush for mechanically cleaning particularly scratch-sensitive surfaces, having a brush shell with a plurality of bristles attached to it, a method for producing such a brush and its use.

The state of the art in practice is to dissolve or disperse dirt particles on surfaces using a suitable solvent, usually water, and then rinse them off. Detergents are often used as surface-active substances to reduce the amount of work required in the cleaning process. To remove stubborn incrustations that cannot be easily dissolved or rinsed off surfaces, the cleaning process is usually supported by mechanical treatment of the dirty surface, for example using suitable brushes.

This principle is used, among other things, in automatic car washes. A particular problem arises with the vehicle paintwork commonly used today. When painted vehicles are frequently cleaned in automatic car washes, especially

On vehicles whose paintwork is only a few months old, the painted surfaces show significant damage.

This is related, among other things, to the nature of the paint used. The binding agents that make up the main components of the paint are dissolved in solvents or thinners in order to make the paint easier to apply. In order for paint applied in liquid form to perform its protective function, it must harden. In the automotive industry, paint systems that can be diluted with water are increasingly being used for vehicle bodies for environmental reasons. These are preferably deposited on the vehicle body using an electro-dip painting process (electrophoretic painting). As an alternative, a completely solvent-free electrostatic coating (powder coating) is also used on the bodywork.

Apparently the final hardening times of the paints commonly used today for vehicle bodies are in the range of weeks and months, and in some cases the hardness that could be achieved with conventional non-aqueous paints is not achieved at all. This inevitably leads to sanding marks and damage in the form of scratches or fine grooves remaining on painted vehicle surfaces after mechanical cleaning processes, which, due to their fineness, are sometimes only visible under a microscope, but in their entirety are clearly visible as a whitish veil. However small and fine these paint damages may be, the fact is that even the finest paint damage can have a detrimental effect on the paint's function as protection, particularly against surface corrosion, and make it appear dull.

The rotating washing rollers used in automatic car washes today often have plastic bristles. The state of the art includes round or profiled

Monofilaments and ribbons made of polypropylene or polyamide. Although the round or profiled monofilaments have a relatively smooth surface, the damage to painted surfaces can occur through contact or grinding of fine dirt particles during the cleaning process, in which the monofilament bristles are drawn in a rotating manner over the surfaces of the vehicles. Even previous attempts with ribbon-like bristle structures or fleece-like strips have not been able to solve these problems. In particular, these structures fray after prolonged use and have to be replaced frequently. Finally, it has been shown that even strips or ribbons as bristles on rotating brush rollers cannot prevent the grinding of fine dirt particles on surfaces. In addition, the use of ribbons or strip structures that have become ragged can cause threads to wrap around protruding parts of the car (windscreen wipers, etc.), which means that such windscreen wipers are literally ripped out and pulled over the entire painted surface, destroying the paint.

As an example of scratch-sensitive non-painted surfaces, noise protection elements made of acrylic glass were mentioned at the beginning. Noise protection elements of this type, such as those from

EP-A 0 407 852, when cleaning the relatively easily soiled surfaces using rotating brushes, as is common on special cleaning vehicles, scratches are often observed, which in turn has a negative impact on the durability of the panels. If the noise protection elements are not cleaned, their suitability as transparent elements is called into question in the long term. If the panels are coated with a scratch-resistant coating, they can be cleaned with conventional brushes, but the scratch-resistant coating is relatively expensive. A suitable tool for gentle and effective cleaning of the

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Transparent noise protection elements made of acrylic glass without scratch-resistant finish are therefore very desirable.

In view of the state of the art indicated and discussed here, the object of the invention was to develop a brush of the type mentioned at the beginning in such a way that it allows the mechanical cleaning of scratch-sensitive surfaces in a gentler manner than known brushes. The aim is to avoid the formation of haze on paints based on water-based systems, while at the same time maintaining the good cleaning effect of known brush structures. Among other things, the new brush should be easy to use as a cleaning element in automatic car washes or on cleaning vehicles.

In particular, the new brush is intended to reduce the risk of damage to the paintwork, which occurs when protruding parts of the bristles are wrapped around, possibly torn off and scratched across the paintwork.

A further object of the invention is to provide a simple method for producing such a brush element. Finally, the application of a brush element within the scope of the inventive concept should also be specified.

The above-mentioned and other tasks not specified in detail are solved by a brush of the type mentioned at the beginning, which has the feature of the characterizing part of claim 1. Advantageous embodiments of the brush according to the invention are the subject of the subclaims dependent on claim 1.

In terms of the method, the objects underlying the invention are solved by a method according to claim 12. Regarding the

Application of the brush, the cleaning method according to claim 13 and the use according to claim 14 represent solutions to the problem.

Because the bristles of the brush according to the invention consist of a flocked yarn, it is possible in an astonishingly simple and not readily predictable way to improve the mechanical cleaning of scratch-sensitive surfaces in such a way that, with undiminished cleaning performance (compared to bristles made of unflocked yarn), a significantly lower degree of damage to the cleaned surfaces results. While the conventional bristles of brushes on washing rollers in car washes cause deposits and damage to the paintwork of automobiles, which consist of the yarn material itself together with grinding marks of dirt, or tend to wrap around objects that protrude from the paintwork surfaces, brushes according to the invention, whose bristles consist of flocked yarn, do not cause these deposits and grinding marks under otherwise identical conditions. In addition, there is no wrapping around windscreen wipers etc. that must be cleaned during the cleaning process of painted surfaces on vehicles. At the same time, the cleaning performance of the brushes according to the invention is better than that of conventional brush structures.

The essential characteristic of the brushes or brush elements according to the invention are the bristles made of flocked yarns. In the invention, the yarn underlying the flocked yarn is also referred to as the core, while the fibers used to flock the core are also called flock.

In the context of the invention, the term yarn according to DIN 60 900 in the sense of "simple yarn" is understood as a single-threaded textile structure consisting of filaments (continuous fibers). Staple fibers, which according to the standard may be counted as yarns, cannot be used as a core according to the invention, since

when used, the bristles can become frayed and the paint and protruding parts can be damaged by wrapping around and subsequently tearing off. The flocked yarn according to the invention can in particular be a filament yarn consisting of one or more filaments that can be produced with or without twist.

Flocked yarns are textile structures in which the surface of the yarn has flock. Flock is filaments cut to very short lengths and not intended for spinning, which are suitable for flocking textile substrates using special processes. The flocking of the bristle yarns has the particularly advantageous effect for the cleaning application of the flocked yarns that the actual yarn, which is often also referred to as the core of the flocked yarn, usually does not come into contact with the surface to be cleaned. This essentially prevents material deposits from the yarn on the surfaces to be cleaned from the outset. If the core of the flocked yarn does come into contact with the surface to be cleaned, the force exerted by the yarn on the surface is significantly reduced by the flock. Another significant advantage of flocked yarns as bristles on cleaning brushes is that the flock fibers are so fine-density compared to yarns without flocking that they do not create any deposits themselves and remove the dirt particles without leaving any abrasive marks in the spaces between the individual fibers of the flock.

In principle, within the scope of the invention, brushes with flocked yarns made from a variety of material combinations familiar to the expert can be used as bristles. In a preferred embodiment, the brush of the invention is characterized in that the flocked yarn has a monofilament made from a thermoplastic material as its core. Monofilament made from

Thermoplastics are ideally suited for the application area according to the invention due to their range of properties. Monofilament yarn is a filament yarn which, as already mentioned, consists of a single filament, with or without twist. In general, a monofilament yarn with a diameter of more than about 0.1 mm is referred to simply as a monofilament or wire.

The monofilament that acts as the core is made of a thermoplastic. Thermoplastics, also known as thermoplasts, are made of linear or slightly branched polymers. Their operating temperature is below the melting point for crystalline polymers, and below the glass transition temperature for amorphous polymers. When heated above these characteristic temperatures, they change into an easily deformable "plastic" state. This "plastic" state can be described as liquid in terms of the order of the molecules, but as viscoelastic in terms of rheological behavior. When cooled below the characteristic temperatures, the formed structures take on the typical characteristics of thermoplastics: quite high dimensional stability under short-term stresses and more or less pronounced creep under long-term stresses. When heated again, they become plastic again. The thermoplastics that can be used as material for the core include, for example, polyvinyl esters, polyvinyl ethers, polyvinyl halides, polystyrenes, polyvinylene oxides, polyvinylene sulfides, polycarbonates, polysulfones, polyamides, polyether ketones, polyether ether ketones, polyether sulfones, polyimides, polyether imides, polyfluoroalkenes, polyester carbonates, poly(meth)acrylates, polyolefins such as HDPE (high density polyethylene), LDPE (low density polyethylene), PP (polypropylene), polyesters, polyoxymethylenes, liquid crystalline polymers with mesogenic groups in the main and/or side chain and similar polymers, such as polymer blends, i.e. mixtures of the aforementioned thermoplastic polymers, such as

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for example a blend of polystyrene with polyparaphenyl oxide as well as copolymers based on the aforementioned polymer materials. Preferred materials are or are based on polyolefins, polyesters and polyamides.

The core of the fiocked yarns, which can be used for the bristles of the brush according to the invention, is produced using processes familiar to those skilled in the art. If monofilaments or a monofilament made of a thermoplastic material are used as the core, a melt spinning process is preferred. In monofilament production, spinning, drawing, post-treatment and winding are often carried out in a continuous process.

With regard to the diameter of the core, it should be noted that this can vary over a wide range of between 0.1 and approx. 2 mm. The diameter of the core is preferably between 0.5 and 1.5 mm, with diameters in the range of around 0.8 mm being particularly preferred. However, depending on the intended use, other diameters of the core, which can also be referred to as inner threads, are also possible.

The core of the bristle of the brush according to the invention has a flocking as an essential element. The material of the flock is not particularly critical in itself. It is particularly advantageous if the surface of the core is flocked with fibers made of a plastic material to achieve a plush, velvet or velour-like texture of the flocked yarn. The plastic material must be selected so that it can be used under the desired cleaning conditions. In principle, a whole range of fiber raw materials are suitable for the flock, depending on the specific flocking process. These include viscose, polyamides, polyesters, polyacrylic fibers, polypropylenes. In particular,

The thermoplastics that are preferably used to manufacture the core are ideally suited as materials for the flock.

Basically, the flock forms either an unoriented or oriented fiber layer on the surface of the core. In the latter case, depending on the fiber length and fiber fineness of the flock, a plush, velvet or velour-like surface is created.

In a favorable embodiment of the invention, the flock consists of cut fibers whose length is approximately in the range between 0.1 and 3 mm. Preferred length ranges for use with the brushes according to the invention are fiber lengths of between 0.5 and 2 mm, with a flock made of fibers with a length of approximately 1 mm being particularly preferably used. The titer range of the fibers for the flock is approximately in the range between 1 and 10 dtex. A titer range of approximately 1.5-4 dtex is preferred. The flock can particularly expediently consist of a titer of approximately 1.7 - 2.2 dtex and a length of 1-3 mm.

Although flocking with unoriented fibers is also possible, it is particularly preferred according to the invention if the flock on the surface of the core assumes an orientation in which the fibers of the flock protrude from the surface of the core approximately radially with respect to the core diameter. In this case, it is particularly advantageous for gaps to form between the individual flock fibers, whereby these gaps serve to absorb dirt particles and remove them from the surface to be cleaned. Since the dirt particles are wrapped in the gaps between the fibers of the flock during the cleaning process, this prevents dirt particles from grinding on the surface to be cleaned.

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The flocked yarns to be used as bristles according to the invention can be fully or only partially flocked. This makes it possible to provide flocking only in the areas that actually come into contact with the surface to be cleaned. Depending on the intended use, it may be preferable for the core to be flocked all around. Alternatively, it may also be preferable for the core to be flocked only partially, almost ornamentally.

In any case, within the scope of the invention, it is ensured that the weight ratio of flock to core (w/w) is between approximately 0.1 and 10. If too many flock fibers are anchored on the surface of the core, the spaces between the fibers may become too small, so that larger dirt particles can no longer be gently removed. If the number of flock fibers on the core surface is too small, there is a risk that the impacts that are exerted on surfaces to be cleaned, for example when brushes rotate, can no longer be avoided. The weight ratio of flock to core (w/w) is expediently approximately 0.3 to 1.

The stiffness of the yarn used is also of great importance for the invention. Stiffness is understood here as a material property of the flocked yarn, which, in contrast to stiffness, does not include the cross-sectional dimensions of the flocked yarn. The stiffness of the flocked yarn used is mainly caused by the stiffness of the inner thread, i.e. the core of the flocked yarn. This should be sufficiently large to enable the exertion of sufficient force on dirty surfaces to remove particles. In particular, if the stiffness of the flocked yarn is too low, i.e. if the bristles of the brush according to the invention are too floppy overall, a poorer cleaning performance is to be expected than with correspondingly stiffer bristles.

Furthermore, if the flocked yarn is too stiff, there is a risk of curling, as is the case when using yarn made from spun twisted threads. Finally, floppy bristles tend to wrap around surface irregularities. In the range of the SU values mentioned, curling or wrapping around objects or irregularities that protrude from the surfaces to be cleaned can be effectively avoided. The unit [SU] used to characterize the stiffness of the bristles stands for "stiffness units". The unit [SU] clearly defines the "flexural rigidity". 1 [SU] is the bending moment (in p-cm) that a flat test specimen with a width of 1.5" has with a clamping length of 5 cm when it is deflected by 15°. In the context of the invention, the stiffness according to Taber is determined using a Teledyne Taber Stiffness Tester, model 150-6, 115V-50/60 HZ and corresponds to the value according to the size designated there as "bending stiffness" [SU]. In the case of non-flat samples, such as the flocked filament yarns according to the invention, a bending stiffness of 1 SU is present if a bending moment of 1 p-cm is measured with a clamping length of 5 mm and a deflection angle of 15°. If the bending moment of a sample has been determined with a clamping length other than 5 cm, this value (dimension ρ ■ cm) only needs to be multiplied by a fixed factor. to obtain the flexural stiffness in stiffness units (SU). This is also used for measurements with the Stiffness Tester, when the flexural stiffness of the sample is below 10 SU. It is then possible to work with a clamping length of 1 cm (0 - 10 SU range) or even 0.2 cm (0 - 1 SU range).

Materials with a bending stiffness of less than 10 SU are measured at a clamping length of 1 cm.

In a preferred embodiment of the invention, the flocked yarn has a stiffness of between 2 and 8 SU. The stiffness of the flocked yarn is expediently in the range between 4 and 6 SU.

The invention also relates to a method for producing a brush for mechanical cleaning of surfaces that are particularly sensitive to scratches, wherein the method is characterized in that a core made of a thermoplastic is provided, the core surface is coated with an adhesion promoter, the coated core is exposed to an electrostatic field, the flock is anchored in the electrostatic field in the coating of the core to obtain a flocked yarn, and a plurality of flocked yarns are attached as bristles in a brush body.

Depending on whether an unoriented or oriented surface of the flocked yarn is desired, different methods are used. According to the invention, a method is preferred in which the flock is oriented on the core. The short fibers of the flock, unless they already have sufficient electrical conductivity, are first provided with an appropriate preparation. Zirconium salts in combination with softening antistatic agents are suitable for this. The fibers of the flock are then electrically charged in a flock radiator and fly along the field lines of a strong electrostatic field towards the substrate prepared with an adhesion promoter (adhesive) and drill vertically into the adhesive layer, giving the substrate the desired surface. In particular, the flock fibers protrude radially from the core (inner thread) in a velvety structure when the core rotates around its own transverse axis during flocking.

The adhesion promoter layer used in this process varies with the nature of the material of the inner thread or the nature of the material of the flock. The adhesion promoters that can be used include similar substances to those used, for example, in the lamination of plastics. Possible adhesion promoters include those based on polyurethanes, for example polyurethane two-component adhesives.

Acrylates, polyvinyl chloride plastisols, EVA, epoxies and all other types of aqueous dispersion adhesives, of which the thermoreactive ones or those that can be cross-linked via precondensates provide the highest levels of fastness. Aqueous adhesives are preferred, as they have the advantage of supporting the build-up of the electric field in the process described. In addition, these aqueous adhesion promoters are relatively rich in solids and their viscosity can be adjusted very variably, so that on the one hand they do not offer too much resistance to the flock when it hits them, but on the other hand they are so stiff, i.e. short-viscosity, that they hold the penetrated fibers vertically and do not allow them to tip over.

Particularly preferred for the yarns flocked in accordance with the invention as well as for the process according to the invention for producing the brushes are adhesion promoters based on (meth)acrylates. The adhesive layer that surrounds the inner thread preferably has a thickness of about 100 to 200 μm. Furthermore, the process for producing the brush according to the invention is preferably carried out in its flocking step in such a way that the flock fibers penetrate about 80 μm deep into the adhesion promoter layer, preferably based on an acrylate, and are anchored there.

Another subject of the invention is a method for mechanically cleaning scratch-sensitive surfaces, which is characterized in that the surfaces to be cleaned are mechanically treated with a brush, whereby the core or inner thread of the bristles does not touch the surfaces themselves. As previously described, scratching on sensitive surfaces is particularly advantageously avoided in this way.

The brush according to the invention can be manufactured in many different versions. The brush body can be made of any material and adapted to all given requirements. The anchoring of threads or, in the case of the invention, flocked yarns in the

The brush body itself is state of the art. In particular, half-shell-shaped modules can be manufactured with the flocked yarns of the invention, which can be used as washing rollers in car washes after two half-shells are joined together. The flocked yarns according to the invention are attached to the half-shells in a known manner. A thread (flocked yarn) of a suitable length is bent, put through two holes in the half-shell and then attached to the half-shell. The two thread halves then protrude as bristles on the back of the half-shell.

Another use of the brushes according to the invention is, for example, with cleaning vehicles, which are also equipped with rotating brushes and can be used to clean noise barriers and the like.

In the following, the invention is explained in more detail using embodiments with reference to the attached figures.

In the figures show

Figure 1 shows a schematic cross section through a

half-shell-shaped brush element with a plurality of bristles according to the invention;

Figure 2 shows the detail "X" from Figure 1 in scale 1:1;

Figure 3 is an enlargement of a photograph of a

painted surface after cleaning with a conventional brush; and

Figure 4 as Figure 3, but after a washing process with

a brush according to the invention, also a painted surface.

Figure 1 shows a possible design for a brush element 1 according to the invention in cross section, whereby for the sake of simplicity some bristles 2 are only indicated or omitted. The brush shown consists of a half-shell-shaped body or base 3 in which a large number of bristles 2 are attached. To attach the bristles 2, holes are provided in the base 3 at predetermined locations, which are not shown in detail. Each hole can be used to attach a plurality of bristles 2, for example up to ten. The length of the bristles 2 is in the example such that the distance from the center of the radius of the brush bowl to the free end 2a of the bristles 2 is approximately 490 to 510 mm.

The bristles are now attached to the brush shell as shown in detail "X" (see Figure 2).

The fastening consists in particular of rear-side wiring with non-oxidizing metal wires.

If two of the half-shell-shaped elements 1 are joined together to form a roller, a roller that can be set in rotation is obtained, such as is used in car washes for cleaning painted vehicles.

Example 1: Production of bristles according to the invention:

The bristles attached to the brush shell 3 shown in Figures 1 and 2 are manufactured, for example, as follows: The first manufacturing step comprises coating a polyester monofilament made of an aqueous dispersion of a methyl acrylate in a layer thickness of approximately 80 μm.

This is followed by flocking with a 1.5 mm polyamide flock and condensation of the flocked monofilament at 200 ^° C for 30 seconds.

Example 2 and comparison example: Cleaning effect:

The cleaning effect and the advantageous paint-protecting effect of the brush according to the invention in comparison to a conventional brush is illustrated in Figures 3 and 4.

In an example and a comparative example, a freshly painted surface was subjected to a cleaning process with a brush that had bristles made of flocked monofilaments according to the invention for comparison purposes. On the other hand, in parallel, the same painted surface was subjected to a cleaning process in which a brush was used that had conventional bristles.

The type of paint tested, the conditions of the cleaning process and the characteristics of the materials used are given below.

The test involved the high-gloss paint (gray) of a car, washed in the standard program of a small-service gantry system with the addition of a polyethylene-based dispersant. Washing time 5 minutes.

In example 2 (Figure 4), bristles according to the invention from example 1 were used. In the bleaching example (Figure 3), polypropylene monofilaments (diameter 0.6 mm) were used as bristles.

Figures 3 and 4 show the results. It is clearly visible that after cleaning with a conventional brush, the paint as shown in Figure 3 has a large number of fine and deep scratches and

Cracks. These can be seen in Figure 3 as light line-shaped traces. In comparison, Figure 4 shows that both the quantity and quality of the scratches and cracks (white traces on a dark background) are significantly lower than in the illustration in Figure 3. Both images show a section of a painted surface of the same size.

Further embodiments and advantages of the invention will become apparent from the following patent claims.

Claims (9)

Protection claims 1. Washing roller which is to be set in rotation for the mechanical cleaning of painted surfaces of motor vehicles, in particular those sensitive to scratches, comprising a roller half-shell with a plurality of bristles attached thereto, wherein the bristles consist of a flocked yarn, which has a monofilament made of a thermoplastic material as a core, characterized in that the yarn has a stiffness between approximately 2 and 8 SU. 2. Roller according to claim 1, characterized in that the surface of the core is flocked with plastic fibers to achieve a plush, velvet or velour-like texture. 3. Roller according to claim 2, characterized in that the length of the fibers is between 0.1 and 3 mm, preferably between 0.5 and 2 mm. 4. Roller according to claim 2 or 3, characterized in that the flock of the yarn consists of a titre between 1 and 10 dtex, preferably between 1.5 and 4 dtex. 5. Roller according to one or more of claims 2 to 4, characterized in that the weight ratio of flock to core (w/w) is between approximately 0.1 and 10. 6. Roller according to claim 5, characterized in that the weight ratio of flock to core (w/w) is between approximately 0.3 and 1. 7. Roller according to one or more of the preceding claims, characterized in that the stiffness of the yarn is in the range between approximately 4 and 6 SU. 8. Roller according to one or more of claims 1 to 7, characterized in that the core is flocked all around. 9. Roller according to one or more of claims 1 to 7, characterized in that the core is flocked in an ornamental manner.