EP3386753B1 - Scraper - Google Patents

Description

Technical field

The invention relates to a doctor blade comprising a doctor blade body with a working edge, and a first doctor blade side, which faces a printing cylinder in particular during operation, and a second doctor blade side, which faces away from the printing cylinder in particular during operation, the doctor blade body being provided with a coating comprising a polymer is, wherein the coating comprises at least in a partial area particles. The invention further relates to a method for producing such a doctor blade.

State of the art

Squeegees are used in the printing industry as well as in paper manufacture.

In the printing industry, squeegees are used in particular to wipe off excess printing ink from the surfaces of printing cylinders or printing rollers. The quality of the squeegee has a decisive influence on the printing result, especially in rotogravure and flexographic printing. Bumps or irregularities in the working edges of the squeegee in contact with the printing cylinder lead e.g. B. to incomplete stripping of the printing ink from the webs of the printing cylinder. This can lead to an uncontrolled release of printing ink on the print carrier.

The working edges of the squeegee are pressed against the surfaces of the printing cylinders or printing rollers during the wiping and are moved relative to these. This means that the working edges, particularly in rotary printing presses, are exposed to high mechanical loads on the one hand, which result in corresponding wear - on the other hand, high demands are placed on the working edges of the doctor blade, so that precise stripping is ensured over the longest possible application period. Squeegees are therefore fundamentally consumables that have to be replaced periodically. This means that the manufacturing costs must be kept low and the service life should be as long as possible, especially if the squeegee is of consistently high quality.

Squeegees are mostly based on a squeegee body made of steel or plastic with a specially shaped working edge. In order to improve the service life of the squeegee, the working edges of the squeegee can also be provided with coatings or coatings made of plastics, lacquers and / or metals. The material properties of the coatings significantly influence the mechanical and tribological properties of the doctor blade. Such doctor blades are known from the prior art.

Such a doctor blade is used, for example, in the EP 0 911 157 B1 described. This relates to a squeegee for scraping excess printing ink off the surface of a printing form. In order to reduce the wear on the surface of the printing form that is in contact with the squeegee, the lamella and also the region of the rear squeegee part adjoining the lamella are provided with a coating over the entire length of the squeegee, which coating consists of lubricant or at least contains lubricant particles. The coating can comprise a carrier material in which both lubricant particles and particles of a wear-resistant material are embedded.

Squeegees coated in this way are still not entirely satisfactory in terms of manufacturing costs and precision when wiping. document WO 2013/133762 discloses a doctor blade according to the preamble of claim 1 and a method according to the preamble of claim 9.

In the paper industry, doctor blades are also referred to as doctor blades, doctor blades or scrapers, depending on the application. With a doctor knife or doctor blade, e.g. superfluous coating color (for example pigments, binders, additives, etc.) can be removed from a paper substrate or a paper web. As in the printing industry, the service life of the doctor blades, doctor blades or scrapers can be improved by providing the working edges of the doctor blade with coatings or coatings made of plastics, lacquers and / or metals. The known systems are also not entirely convincing in the field of doctor blades for the paper industry or for paper production. There is therefore still a need for improved doctor blades which do not have the disadvantages mentioned above.

Presentation of the invention

The object of the invention is to provide a doctor blade belonging to the technical field mentioned at the outset, which can be used as advantageously as possible with low manufacturing costs for applications in the printing industry or in paper manufacture. In particular, the squeegee should be usable for applications in the printing industry and allow the most exact possible wiping of printing ink.

The solution to the problem is defined by the features of claim 1. According to the invention, the particles are designed as hard material particles and a mass fraction of the hard material particles in the coating on the first doctor blade side is higher than a mass fraction of the hard material particles in the coating on the second doctor blade side.

The first squeegee side, in particular the side facing the printing cylinder, comprises at least the contact area between the squeegee and the printing roller or paper substrate during an application, for example when doctoring printing ink. Furthermore, the second squeegee side, in particular the side of the squeegee facing the printing cylinder, comprises the surface of the squeegee which forms an angle of less than 90 ° with a tangent to the printing roller or to the paper substrate in the contact area with the squeegee. In other words, the side of the doctor blade facing the printing roller or the paper substrate is the surface of the doctor blade which can be reached directly, that is to say without a passage through the doctor blade, through an extended radius of the printing roller or the paper substrate. In the case of a flat paper substrate, the radius corresponds to a surface normal of the paper substrate.

In a method for producing such a doctor blade, a doctor blade body with a working edge is coated with a coating comprising a polymer, a first doctor blade side which faces the printing cylinder in particular during operation and a second doctor blade side which in particular faces away from the printing cylinder in operation. which comprises particles in at least one partial area. The particles are designed as hard material particles and a mass fraction of the hard material particles in the coating on the first doctor blade side is higher than a mass fraction of the hard material particles in the coating on the second doctor blade side.

The term "doctor blade" is to be understood broadly here and includes both doctor blades for applications in the printing industry and in the paper industry. In particular, the doctor blade is a pressure doctor blade, doctor blade, doctor blade and / or scraper. In a particularly preferred embodiment, the squeegee is a printing squeegee, which is provided in particular for doctoring off printing ink from a printing cylinder.

The squeegee body preferably has an elongated shape and can, for example, be in the form of a band, the working edge being oriented in a longitudinal direction of the band. Depending on the strength, material and dimensions of the squeegee body, this can be present, for example, as a tape roll.

The coating comprising a polymer preferably comprises more than 50% by weight (weight percent) of polymers, in particular more than 75% by weight of polymers, particularly preferably more than 90% by weight of polymers. Furthermore, the polymer content is preferably less than 99% by weight, particularly preferably less than 95% by weight. Polymers are therefore preferably the main component of the coating. The aforementioned proportions of the polymers in the coating are based on the coating of the ready-to-use doctor blade. In these cases, the coating comprising a polymer can also be referred to as a polymer-based coating.

The coating comprising the polymer may have a lower mass fraction of hard material particles than on the doctor body in the ready-to-use state of the doctor blade because of solvents or other volatile substances before it is applied to the doctor body. Such volatile substances can be removed by a drying step during the manufacture of the doctor blade.

In particular, the polymer in the coating forms a continuous phase and / or a dispersion medium for the hard material particles in the coating. The hard material particles are dispersed and / or embedded in particular in the continuous phase of the polymer.

In the present case, the polymer comprises or consists in particular of an organic polymer. The polymer can be a homopolymer or a copolymer. Homopolymers essentially consist of a single type of monomer, while copolymers consist of two, three or even more chemically different types of monomers. It is also possible for the polymer to be in the form of a so-called polymer blend or as a mixture of several different homopolymers and / or copolymers.

In particular, the polymer is a thermoset, thermoplastic and / or an elastomer. Preferred are e.g. Thermosets. After curing, thermosets have a three-dimensional crosslinking and usually cannot be deformed after they have hardened. In the present case, thermosets have proven to be particularly robust and, at the same time, surprisingly advantageous in terms of their sliding and wiping properties.

Examples of polymers which can be provided are epoxy resins, phenolic resins, such as phenol-formaldehyde resins (novolacs and resols), melamine-formaldehyde resins and saturated and unsaturated polyester resins or mixtures thereof. The polymers can further comprise rubber, polyurethanes, polyureas, thermoplastics or mixtures thereof. The thermoplastics can include, for example, acrylonitrile butadiene styrene, polyamide, polycarbonate, polyethylene, polypropylene, polystyrene, polyvinyl chloride, or mixtures thereof. The skilled person is also aware of other possible polymers which can be provided in pure form or as mixtures for the production of the coating. The polymer mixtures can in particular comprise two or more different polymers.

In variants, the coating can also comprise less than 50% by weight of polymer.

If the polymer forms a continuous phase and / or the dispersion medium for the hard material particles in the coating, the continuous phase formed by the polymer and / or the dispersion medium formed by the polymer advantageously has less than 50% by weight, in particular less than 25% % By weight, preferably less than 10% by weight, in particular less than 5% by weight, very particularly preferably less than 2% by weight or less than 1% by weight, of a metal. The continuous phase and / or the dispersion medium for the hard material particles in the coating is very particularly preferably essentially free of metals. “Metal” means in particular metal atoms bonded to metal. In particular, individual metal ions, metal salts or covalently bound metals do not fall under the term "metal". In this case, the metal is in particular nickel, chromium, tin, alloys of nickel and chromium, alloys of nickel and tin and / or alloys of nickel and phosphorus, in particular nickel and / or alloys of nickel and phosphorus.

According to a preferred embodiment, the coating comprising a polymer in particular has a total of less than 50% by weight, advantageously less than 25% by weight, preferably less than 10% by weight, in particular less than 5% by weight, entirely particularly preferably less than 2% by weight or less than 1% by weight of a metal. The coating comprising a polymer is very particularly preferably essentially free of metals.

In particular, all coatings of the doctor blade each have a metal content of less than 50% by weight, advantageously less than 25% by weight, preferably less than 10% by weight, in particular less than 5% by weight , very particularly preferably less than 2% by weight or less than 1% by weight. All coatings of the doctor blade are very particularly preferably essentially free of metals.

The manufacturing processes for the squeegee can be simplified by reducing the metal content or dispensing with metals. It has surprisingly been found that polymer-comprising coatings or polymer-based coatings can be used instead of metal-based coatings without significant losses in terms of the quality of the doctor blade.

The coating comprising a polymer advantageously forms the outermost coating of the doctor blade, at least in the area of the working edge, preferably in all coated areas of the doctor blade. In any case, the coating of the doctor blade comprising a polymer is in direct contact with the printing form or a paper substrate when used, which gives the best possible effect.

The hard material particles typically serve to improve the wear behavior of the doctor blade, but can also produce other effects. For this purpose, the hard material particles are preferably dispersed in a coating which also contains the polymer or the polymers.

The hard material particles are advantageously distributed uniformly in the coating on the first doctor side and on the second doctor side. The coating thus has a heterogeneous structure due to the dispersed hard material particles. The Coating can be sprayed, sprayed, rolled, painted or otherwise applied to the doctor body, for example as a lacquer.

According to the invention, the two doctor blade sides of the doctor blade have coatings with different mass fractions of hard material particles. This means that the hard material particles can occur in larger concentrations where the doctor blade is expected to be subjected to increased stress. The hard material particles can thus be used in an economical manner, in particular since the hard material particles are preferably more strongly represented in the area of the greatest stress on the doctor blade, so that hard material particles can be saved in the less stressed areas of the doctor blade. The manufacturing costs can thus be kept low while the doctor blade quality remains essentially the same. At the same time, the other side of the squeegee has greater homogeneity and improved adhesion to the squeegee body due to the reduced mass fraction of hard material particles. Overall, a more even wear of the coating of the doctor blade can be achieved.

The first squeegee side, which faces the printing cylinder or the paper in particular during operation, preferably comprises an end face of the working edge, which lies on the printing cylinder or a paper substrate in operation. The coating with the higher mass fraction of hard material particles can thus be provided exactly where the doctor blade is subjected to the highest stress. The coating with the higher mass fraction of hard material particles can, however, also extend further on the first side and in particular also cover the entire first doctor side. In a preferred embodiment, however, the coating with the higher mass fraction of hard material particles covers at least the front side of the working edge and thus at least a partial area of the first doctor side, preferably more than 20%, particularly preferably more than 50%, further preferably more than 70% of the surface the first squeegee side. The coating particularly preferably covers at least the entire working edge. The coating also preferably covers, in addition to the working edge, a further partial region of the doctor blade that is peripheral to the working edge.

The second squeegee side comprises in particular the side facing away from the printing cylinder or the paper during operation. A transition between the coatings of the first doctor blade side and the second doctor blade side can be fused, for example both coatings being applied before the doctor blade is subjected to a drying process at a temperature above the pour point of the coatings. However, the two coatings on the first and second doctor blade sides can also overlap, in which case an overlap area is preferably located on the side facing away from the printing cylinder during operation, so that the quality of the doctor blade is not impaired during operation. Under certain circumstances, however, the overlap can also be smoothed in a thermal process step. Furthermore, in a first step both sides can be coated with a coating with the lower mass fraction of hard material particles (respectively without hard material particles), whereupon the first doctor blade side is coated with a coating with the larger mass fraction of hard material particles in a second step. Other methods are known to the person skilled in the art to reach the doctor blade sides of different hard material particle mass fractions.

The doctor blades coated according to the invention have a high wear resistance and, accordingly, a long service life. Furthermore, the working edges of the doctor blade according to the invention are well stabilized. This results in a sharply delimited contact zone between the doctor blade and the printing cylinder or the printing roller, which in turn enables the ink to be precisely wiped off. The contact zone remains largely stable over the entire printing process. The streaking during the running-in phase in the printing process is also low. Overall, there are hardly any effects affecting the printing process. The doctor blade according to the invention therefore makes it possible to achieve an essentially constant print quality during the entire printing process. The doctor blades are also advantageous in applications in the paper industry, e.g. as a doctor knife.

Furthermore, the doctor blade according to the invention has good sliding properties on the printing cylinders or printing rollers normally used, so that when the doctor blade according to the invention is used, the printing cylinders or Printing rollers can be reduced. This also applies to the sliding properties on paper.

According to a special embodiment, hard material particles are present both in the coating on the first doctor side and in the coating on the second doctor side. A mass fraction of the hard material particles in the coating on the first doctor blade side and a mass fraction of the hard material particles in the coating on the second doctor blade side are in each case ≥ 0.1% by weight, in particular ≥ 1% by weight.

A mass fraction of the hard material particles in the coating with the higher proportion or in the coating on the first doctor blade side is, for example, in the range from 0.1-60% by weight, in particular 1-45% by weight, preferably 5-40% by weight. or 10-30% by weight. This has proven to be particularly suitable.

A ratio of the mass fraction of hard material particles in the coating on the first doctor blade side to the mass fraction of hard material particles in the coating on the second doctor blade side is in particular greater than 2, preferably greater than 10, particularly preferably greater than 100, in particular greater than 1,000.

In a particular embodiment, the ratio of the mass fraction of hard material particles in the coating on the first doctor blade side to the mass fraction of hard material particles in the coating on the second doctor blade side is, for example, in the range from 2: 1 to 1,000: 1, in particular 10: 1 to 100: 1.

The coating of the first doctor blade side particularly preferably comprises hard material particles, while the coating of the second doctor blade side is essentially free of hard material particles. The term “essentially free of hard material particles” is to be understood that, if hard material particles were present, these have no or no significant influence on the wear resistance of the doctor blade. However, it is clear to the person skilled in the art that, due to the production process, a small proportion of hard material particles can still be introduced into the second doctor blade side, in particular in the form of impurities. In particular, based on the total weight of the coating on the second doctor blade side, a mass fraction of less than 1%, preferably less than 0.1%, particularly preferably less than 0.05% is meant. The coating of the second doctor blade side particularly preferably has no hard material particles.

In variants, the second squeegee side can have a substantial proportion of hard material particles, which thus has a positive influence on the wear resistance of the squeegee. However, since the second squeegee side is less stressed in the process, the coating of the second squeegee side has a lower mass fraction of hard material particles than the first squeegee side.

The coating on the second doctor blade side preferably does not comprise any particles. The second squeegee side thus preferably does not comprise any hard material particles, but also no further particles which can influence, for example, the sliding friction or other properties of the squeegee. Since the second squeegee side is exposed to significantly lower mechanical stresses, it may be sufficient if only the first squeegee side comprises particles. It has been shown that the wear resistance of the doctor blade is generally independent of the type of coating on the second doctor blade side. A coating of the second squeegee side, for example with a polymer varnish without particles, can still be useful, for example, to protect the squeegee surface from corrosion or for aesthetic reasons.

In variants, the coating of the second doctor blade side can be provided with particles. These can influence the strength, the sliding properties or other properties of the squeegee, for example.

An average volume-equivalent spherical diameter of the hard material particles is preferably less than 1,000 nanometers, preferably less than 500 nanometers, particularly preferably less than 250 nanometers. The particle size of the hard material particles is advantageously adapted to the respective material of the hard material particles.

The volume-equivalent ball diameter indicates the diameter of a ball with the same volume as the particle under consideration or hard material particle. If the particles are porous, the volume of a particle preferably corresponds to the volume of an outer shell of the particle. Below the average of this value is preferred understood the median of the grain size distribution. In this context, the term "particle size" is used below, but what is meant is the average volume-equivalent ball diameter.

In variants, an arithmetic mean of the ball diameters can also be used instead of the median or a surface-equivalent ball diameter can be determined instead of the volume-equivalent ball diameter.

With such particle sizes, the tribological properties of the doctor blade according to the invention can be optimized. It has been shown that the doctor blade with hard material particles in these sizes has very good wear behavior with an optimal contact zone between the doctor blade and the printing cylinder or paper substrate.

In principle, the particle sizes can also be selected to be larger than 1,000 nanometers. However, if the layer thickness is too small, this can have a negative effect on the quality of the contact zone between the doctor blade and the printing cylinder or paper substrate.

The mean volume-equivalent spherical diameter of the hard material particles is preferably greater than 1 nm, particularly preferably greater than 25 nm, more preferably greater than 50 nm. It has been shown that optimum wear resistance of the doctor blade is achieved in this way. Smaller ball diameters can also be considered depending on the thickness of the coating.

A volume fraction of the hard material particles is preferably 5-30%, particularly preferably 15-20%. With such proportions, a significant improvement in wear properties and stability of the working edge is achieved.

Lower volume fractions are also possible, but generally show a less satisfactory improvement in wear resistance. Excessive volume fractions of the additional component can also have a negative effect on the properties of the doctor blade. For special applications, however, parts by volume higher than 30% may also be suitable.

The hard material particles which are preferably dispersed in the coating can in particular be metals, metal oxides, metal carbides, metal nitrides, metal carbonitrides, metal borides, ceramics and / or intermetallic phases.

The hard material particles particularly preferably comprise at least one of the following substances: metal oxides, in particular aluminum oxide and / or chromium oxide; Diamond, silicon carbide, metal carbide, metal nitride, metal carbonitride, boron carbide, cubic boron nitride, tungsten carbide. These materials have proven to be particularly effective for improving the wear behavior of the coating, in particular in connection with the coating comprising a polymer. The coating can comprise exactly one type of hard material particle.

In an advantageous variant, the hard material particles contain different particles made from at least two different materials. As has been shown, this can produce synergetic effects which improve the wear resistance and quality of the doctor blade far more than expected. Furthermore, it can be advantageous if the hard material particles comprise different particles with at least two different average particle sizes.

Representatives from the series WSi ₂ , Fe ₂ O ₃ , TiO ₂ , ZrO ₂ , ThO ₂ , SiO ₂ , CeO ₂ , BeO ₂ , MgO, CdO, UO ₂ , TiC, VC, ZrC, TaC, Cr ₃ C ₂ , ZrB ₂ , TiN, Si ₃ N ₄ , ZrB ₂ , TiB ₂ . But there are also others, e.g. B. organometallic particles as an additional component to improve the wear behavior of the doctor blade possible. Further metal nitrides, metal carbonitrides, metal borides, ceramics and / or intermetallic phases can also be provided as hard material particles. The hard material particles can also comprise metal particles. Are suitable for. B. metal particles of W, Ti, Zr, Mo, and / or steel. Other metals are known to the person skilled in the art which can be processed into hard material particles. The metal particles can be used alone, in combination with other metal particles and / or in combination with other hard material particles. Hard material particles made of metal alloys can also be used.

Metal particles made of metallic molybdenum have proven to be particularly suitable. Squeegees with a coating based on polymers with metal particles of molybdenum dispersed therein have a very high wear resistance and, accordingly, a long service life. The working edges of such squeegees have a sharply delimited contact zone between the squeegee and the printing cylinder or the printing roller, which enables more precise wiping of printing ink. In a further preferred variant, the metal particles have an average volume-equivalent spherical diameter of 0.01-0.9 μm and a volume fraction of 5-30%, particularly preferably 15-20%.

Doctor blades with a polymer-based coating with metal oxides, metal carbides, metal nitrides, metal carbonitrides, metal borides, ceramics and / or intermetallic phases dispersed therein have a high wear resistance and, accordingly, a long service life, in particular in connection with a polymer-containing or polymer-based coating. Such hard material particles can be embedded extremely stably in the coating and form a hard-wearing bond with the doctor body. As a result, the strength of the coating can be improved overall, and at the same time the working edges of such doctor blades show a sharply delimited contact zone between the doctor blade and the printing cylinder or the printing roller, which in turn enables a more precise wiping of printing ink. The same applies to applications in paper production.

The following metal carbides and / or metal nitrides in particular have been found to be particularly suitable: B ₄ C, cubic BN, TiC, WC and / or SiC. In the case of metal oxides, Al ₂ O ₃ is particularly advantageous.

However, the hard material particles do not necessarily have to be in the form of metal particles, metal oxides, metal carbides, metal nitrides, metal carbonitrides, metal borides, ceramics and / or intermetallic phases. In principle, particles made of other materials are also suitable as hard material particles.

In an advantageous variant, the hard material particles comprise diamond. Diamond with a mono- and / or polycrystalline structure is preferably used. Hard diamond particles have proven particularly advantageous in the doctor blade according to the invention and in particular bring about a further improvement in the wear resistance and stabilization of the working edges of the doctor blade. Among other things, this may be due to the high hardness and chemical and mechanical stability of diamond.

As has been shown, it is in principle possible to use particles of amorphous diamond-like carbon ("diamond-like carbon"; "DLC") instead of or in addition to hard material particles made of diamond with a mono- and / or polycrystalline structure. However, the amorphous diamond-like carbon advantageously has a high proportion of sp3 hybridization so that there is sufficient hardness. Depending on the intended use of the doctor blade, amorphous diamond-like carbon can even have advantages. In general, amorphous diamond-like carbon is also cheaper than diamond.

The hard material particles particularly preferably comprise both SiC and diamond, further preferably a particle size of the SiC being larger than a particle size of the diamond. In particular, the hard material particles comprise SiC with a particle size of 0.7-0.9 μm and diamond with a particle size of 5 nm-0.9 μm, preferably 200-300 nm.

But it is also possible to choose the particle sizes of SiC and diamond differently, so that, for. B. the particle size of the diamond is the same size or larger than the particle size of the SiC. In addition, other combinations of hard material particles are possible, with more than two, for. B. three, four or even more different hard material particles can be combined.

In another preferred variant of the invention, the hard material particles comprise, for example, both SiC and cubic BN, preferably a particle size of BN corresponds approximately to the particle size of the SiC. The particle sizes of the SiC and the cubic BN particularly preferably measure approximately 0.1-0.9 μm.

Furthermore, it has proven advantageous for certain applications if the coating comprises lubricants, in particular lubricating particles, in order to improve the wear resistance. As a result, a lubricating effect can also be achieved when doctoring, which reduces wear. In principle, suitable lubricants or lubricating particles are substances which bring about a reduction in the sliding friction between the doctor blade and the printing cylinder and, in particular, are sufficiently stable so that the printing cylinder is not impaired or contaminated.

For example, polymeric thermoplastics, for. B. perfluoroalkoxylalkane and / or polytetrafluoroethylene, and graphite, molybdenum disulfide and / or soft metals, such as aluminum, copper and / or lead.

A well-suited lubricant is, for example, polytetrafluoroethylene (PTFE). Polytetrafluoroethylene is preferably used in the form of lubricating particles.

In particular, the use of polymeric thermoplastics, but also in the case of other polymers, has the advantage that these lubricants can be incorporated particularly well into the matrix of the coating, in particular since the coating according to the invention is polymer-based.

However, hexagonal BN has also proven to be particularly advantageous as a lubricant. This is particularly in particle form. As has been shown, lubricants, in particular lubricating particles made of hexagonal BN, have improved the wear resistance of the doctor blade in a large number of applications with different printing cylinders. In particular, this is largely independent of the process parameters during doctoring. In other words, hexagonal BN has proven to be an extremely versatile and effective lubricant.

Lubricating particles, in particular lubricating particles made of hexagonal BN, advantageously have a particle size of 50 nm - 0.9 μm, preferably 80-300 nm, more preferably 90- 110 nm. This achieves an optimal effect for a variety of applications. In principle, however, other particle sizes can also be suitable for specific applications.

In a particularly preferred embodiment, both lubricants, in particular lubricating particles, and hard material particles are present in the coating as additives to improve the wear resistance. Ideally, lubricating particles made of hexagonal BN are used together with hard particles made of SiC.

According to a further advantageous embodiment, the coating comprising a polymer advantageously has less than 50% by weight, in particular less than 25% by weight, preferably less than 10% by weight, in particular less than 5% by weight, very particularly preferably less than 2% by weight, in particular less than 1% by weight or less than 0.1% by weight, of particulate lubricants. These are, in particular, particulate organic lubricants, in particular particulate polymer-based lubricants, for example particulate polytetrafluoroethylene (PTFE).

In a particular embodiment, all coatings advantageously have less than 50% by weight, in particular less than 25% by weight, preferably less than 10% by weight, in particular less than 5% by weight, very particularly preferably less than 2 % By weight, in particular less than 1% by weight or less than 0.1% by weight, of particulate lubricants. In particular, all coatings on the doctor blade are essentially free of particulate lubricants.

Due to the coating comprising a polymer or the polymer-based coatings, lubricating particles can be dispensed with if necessary, without the sliding and wiping properties of the doctor blade being significantly impaired. This significantly simplifies production. The coatings comprising polymer already show very good sliding and wiping properties in most applications, some of which are even better than with conventional doctor blades and, if need be, through non-particulate ones Lubricants can be increased in a simpler way.

In a further embodiment, the coating comprises fibers for reinforcing the coating in addition to the hard material particles. The fibers can include, for example, carbon fibers, plastic fibers or the like.

A layer thickness of the coating is preferably 1-30 µm (microns). The layer thickness is more preferably 5-20 μm, particularly preferably 5-10 μm. Such a layer thickness offers optimal protection of the working edge of the squeegee. In addition, the layer thickness measured in this way has a high intrinsic stability, which effectively reduces the partial or complete delamination of the first coating, for example during the doctoring off of printing ink from a printing cylinder.

Thicknesses of less than 1 µm are possible, but the wear resistance of the working edge or squeegee quickly decreases. Thicknesses greater than 30 µm are also feasible. However, these are generally less economical and may also have a negative impact on the quality of the working edge. However, thicknesses of less than 1 µm or more than 30 µm can be advantageous for special areas of application of the doctor blade.

In a particularly preferred embodiment, in addition to the coating comprising a polymer, the doctor blade has at most three, in particular at most two, preferably at most one, in particular no further coating. The coating of the doctor blade very particularly preferably consists solely of the coating comprising a polymer and optionally an adhesive coating. On the one hand, this simplifies production, on the other hand, coatings with few or no additional coatings have proven to be particularly reliable and robust. Incompatibilities between different coatings can thus be reduced or avoided entirely.

However, other coating structures can also be advantageous for special applications.

The doctor blade body is preferably formed from a metal or a metal alloy. Doctor blades made of metals which are robust and corrosion-resistant are particularly advantageous. For these reasons in particular, doctor bodies made of aluminum are particularly advantageous. In addition, doctor blades can also be made of other metals, for example iron, etc. The doctor blade can also be made of a metal alloy, with which the desired properties of the doctor blade can be optimally controlled. The choice of material of the squeegee body is preferably matched to the coating in such a way that an optimal wear resistance of the squeegee and thus the greatest possible service life is achieved, and a precise doctoring is made possible.

Variants can also be used to produce other materials for the doctor body.

In a particularly preferred embodiment, the doctor body is made of steel. Mechanically, steel has proven to be a particularly robust and suitable material for the doctor blade according to the invention. This enables precise squeegees with a long service life to be manufactured cost-effectively.

Instead of steel, however, other metals or metal alloys can, for example, also be used as the base body.

In this case, at least one shell region of the base body that is present with respect to the longitudinal direction is preferably completely and completely covered by a coating. As a result, at least the working edge, the upper side, the underside and the rear end face of the base body opposite the working edge are covered with a coating. The side faces of the base body that are perpendicular to the longitudinal direction can be uncoated. However, it is also within the scope of the invention that the second coating covers the base body completely and on all sides, that is to say the side surfaces of the base body that are perpendicular to the longitudinal direction are also covered with one of the coatings. In this case, at least one of the coatings completely surrounds the base body.

As a result of the fact that at least the shell region of the base body that is present with respect to the longitudinal direction is completely and completely covered with a coating, the essential regions of the base body that do not belong to the working edge are also provided with the coating. This is particularly advantageous in order to protect the base body from the water-based or slightly acidic printing inks and / or other liquids which come into contact with the doctor blade. Optimal rust protection for the squeegee is thus created, in particular with steel base bodies. This further improves the consistency of the print quality during the printing process, since the printing cylinder or the printing roller that is in contact with the doctor blade during the printing process is not contaminated by rust particles, for example. Furthermore, the base body is optimally protected against rust formation during storage and / or transport by a coating applied in the jacket area.

In a further aspect of the invention, however, the doctor blade is only coated where the greatest mechanical stress occurs, namely on the working edge and its peripheral areas. The coating can thus be kept inexpensively. This variant is particularly advantageous in the case of squeegee bodies which are essentially chemically inert, in particular in the area of application of the squeegee. For example, doctor blades made of stainless steel or aluminum may or may not be coated only in the area of the working edge or on the side facing away from the printing cylinder during operation. The material costs during production can thus be reduced.

In a further preferred embodiment, doctor blade body is formed from a plastic or from a plastic material. For special applications, plastic base bodies have proven to be more advantageous than steel base bodies due to their different mechanical and chemical properties. Some of the plastics in question have sufficient chemical stability or inertness compared to typical water-based and slightly acidic printing inks, which means that the base body does not need to be specially protected, as in the case of a base body made of steel. Furthermore, plastics are inexpensive to buy and easy to process. Furthermore, plastics are lighter and therefore also in use, in particular in handling during the maintenance of printing presses and to prefer such. The doctor blade bodies made of plastic also have good properties when coated with a polymer-based coating. The doctor blade body can thus not only be purely adhesive, as in the case of doctor blade bodies made of metal, but may also be chemically bonded to the coating or thermally fused to the coating in a limit phase.

As a plastic material such. B. polymer materials in question. These can include thermoplastic, thermosetting and / or elastomeric polymer materials. Suitable plastics are e.g. B. polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyvinyl alcohol, polyethylene terephthalate, polyamide, polyacetal, polycarbonate, polyarylate, polyether ether ketone, polyimide, polyester, polytetrafluoroethylene and / or polyurethane. Composite structures with fibers to reinforce the polymer matrix are also possible.

In principle, however, basic bodies can also be used, which, for. B. consist both of metal, especially steel, and plastic. Also basic body with other materials, e.g. B. ceramics and / or composite materials may be suitable for special applications.

The doctor body is preferably heated before coating. On the one hand, this ensures that the doctor body is dry for the coating. This can prevent a coating from becoming detached from the doctor body later, for example due to corrosion of the doctor body under the coating. This also ensures that the coating adheres optimally to the doctor body or connects to it. The polymer-based coating therefore has a lower viscosity on the squeegee, which means that the coating can be distributed evenly without streaks or drops forming. In the event that the coating material to be applied comprises solvents, the drying process can be further promoted.

In variants, heating of the doctor blade body before coating can also be dispensed with.

It can also be advantageous if the doctor blade body is roughened, in particular mechanically roughened, before the coating. This can further improve the adhesion between the doctor blade body and the coating. However, this is not absolutely necessary.

In particular, an adhesive coating can be applied before coating the doctor blade body with the coating comprising a polymer. This can be done in addition to or instead of roughening and also enables an improvement in the adhesion between the doctor blade body or possibly already applied layers and the coating according to the invention.

After the application of the adhesive coating and before the coating of the doctor body with the coating comprising a polymer, an intermediate drying step can optionally also take place. Depending on the adhesive coating, this can be advantageous.

The doctor blade body is preferably degreased mechanically and / or electrolytically before coating. Electrolytic degreasing is preferred. This in turn achieves an optimal connection between the coating and the doctor body. Contamination on the squeegee, in particular greasy contamination, can severely disrupt the adhesion between the coating and the squeegee body.

In variants, electrolytic degreasing can also be dispensed with. In this case, another cleaning step can be used, for example a cleaning step with a washing solution, such as an organic solvent or a soap solution.

The doctor for electrolytic degreasing is preferably switched as an anode in order to remove grease from the doctor body by means of cations. In the so-called anodic degreasing, oxygen is formed on the doctor body under the fat layer, which removes the fat layer. Anodic degreasing has the advantage in particular over cathodic degreasing that hydrogen embrittlement can be avoided. The increased power requirement compared to cathodic degreasing is therefore deliberately accepted, particularly in the case of steel doctor blades, in order to protect the doctor blade body.

The degreasing can alternatively also be carried out with interchanged electrodes, as cathodic degreasing. This has the advantage that by forming hydrogen under the fat layer with the same amount of electricity, twice the gas volume can be generated. However, hydrogen embrittlement may have to be accepted. In the case of doctor bodies which are not subject to hydrogen embrittlement, cathodic degreasing can easily be selected in order to obtain more efficient degreasing with lower power consumption. Both techniques can also be used sequentially.

A drying step is preferably carried out after the coating of the doctor blade body, in particular a drying step following the drying step. Any solvents present in the coating can be gently removed in the drying step, while in the hardening step even the smallest remaining amounts of solvents can be removed and the structure of the coating is cured. The hardening step can be purely thermal, that is to say, for example, the coating baked with or on the doctor body. On the other hand, the hardening step can also initiate a chemical process. This can include, for example, a polymerization which is initiated by UV rays. Those skilled in the art are also aware of further such steps which can follow a polymer-based coating.

In variants, the drying step and / or the hardening step can also be dispensed with.

The hardening step is preferably carried out at a temperature of 150 ° C. to 350 ° C., preferably at 200 ° C. to 300 ° C., in particular at 230 ° C. to 270 ° C. In particular, these temperatures are maintained for a holding time of 0.5-15 hours, preferably 0.5-8 hours. Such temperatures and holding times have proven to be optimal in order to achieve sufficient hardening of the coatings.

Temperatures of less than 100 ° C are also possible. In this case, however, very long and mostly uneconomical holding times are required. Higher temperatures than Depending on the material of the base body and the coating, 350 ° C is in principle also feasible, but care must be taken that the polymer-containing coating in particular is not damaged by the hardening step.

After the complete hardening in the hardening step, the coating is preferably subjected to an aftertreatment. This is particularly preferably mechanical post-treatment and / or cleaning. For example, mechanical processing can be carried out, such as grinding, lapping or polishing the coating, or treatment using suitable tools, such as knives, milling cutters or the like.

Aftertreatment can also be dispensed with in variants

From the following detailed description and the entirety of the claims, further advantageous embodiments and combinations of features of the invention result.

Brief description of the drawings

Fig. 1

Einen Querschnitt durch eine erste erfindungsgemässe Lamellenrakel, wobei eine Arbeitskante der Lamellenrakel mit einer polymerbasierten Beschichtung und darin dispergierten Hartstoffpartikeln beschichtet ist;

Fig. 2

Einen Querschnitt durch eine zweite erfindungsgemässe Lamellenrakel, wobei eine Arbeitskante der Lamellenrakel mit einer polymerbasierten Beschichtung und darin dispergierten Hartstoffpartikeln beschichtet ist;

Fig. 3

Einen Querschnitt durch eine dritte erfindungsgemässe Lamellenrakel, welche vollständig mit einer polymerbasierten Beschichtung und darin dispergierten Hartstoffpartikeln beschichtet ist;

Fig. 4

Eine schematische Darstellung eines erfindungsgemässen Verfahrens zur Herstellung einer Rakel.

The drawings used to explain the exemplary embodiment show:

Fig. 1

A cross section through a first lamella doctor blade according to the invention, wherein a working edge of the lamella doctor blade is coated with a polymer-based coating and hard material particles dispersed therein;

Fig. 2

A cross section through a second lamella doctor blade according to the invention, wherein a working edge of the lamella doctor blade is coated with a polymer-based coating and hard material particles dispersed therein;

Fig. 3

A cross section through a third lamella doctor blade according to the invention, which is completely coated with a polymer-based coating and hard material particles dispersed therein;

Fig. 4

A schematic representation of a method according to the invention for producing a doctor blade.

In principle, the same parts are provided with the same reference symbols in the figures.

Ways of Carrying Out the Invention

In Fig. 1 A lamella doctor blade 100 according to the invention is shown in cross-section in contact with a printing roller 170. The lamellar doctor blade 100 includes a base body 110 made of steel, which on the in Fig. 1 has a rear region 120 on the left side with an essentially rectangular cross section. The rear region 120 is provided as a fastening region in order to hold the lamella doctor blade, for example, in a corresponding receiving device of a printing press. A doctor blade thickness, measured from the top 121 to the bottom 122 of the rear area, is approximately 0.2 mm. A length of the base body 110 or of the lamella doctor blade 100 measured perpendicular to the sheet plane is, for example, 1000 mm. The pressure roller 170 can have a direction of rotation 171 with or counterclockwise. Both directions of rotation are possible for applications in flexographic printing. In the present arrangement, the printing roller is rotated clockwise in gravure printing.

On the in Fig. 1 On the right-hand side, the base body 110 tapers in a step-like manner from the top side 121 of the rear region 120 to form a working edge 130. An upper side 131 of the working edge 130 lies on a level below the level of the upper side 121 of the rear area 120, but is essentially parallel or plane-parallel to the upper side 121 of the rear area 120. A concave transition region 125 is present between the rear region 120 and the working edge 130. The underside 122 of the rear region 120 and the underside 132 of the working edge 130 lie in a common plane which is plane-parallel to the top side 121 of the rear region 120 and plane-parallel to the top side 131 of the working edge 130. A width of the base body 110, measured from the end of the rear region to the end face 140 of the working edge 130, measures 40 mm, for example. A thickness of the work area 130 measured from the top 131 to the underside 132 of the working area is, for example, 0.060-0.150 mm, which corresponds approximately to half the doctor blade thickness in the rear area 120. A width of the working area 130, measured on the top 131 of the working area 130 from the end face 140 to the transition area 125, is, for example, 0.8-5 mm.

A free end face 140 of the free end of the working edge 130 runs obliquely downward from the upper side 131 of the working edge 130 to the underside 132 of the working edge 130. The end face 140 has an angle of approximately 45 ° or 135 ° with respect to the top 131 of the working edge 130 or with respect to the bottom 132 of the working edge 130. An upper transition area between the top 131 and the front 140 of the working edge 130 is rounded. Likewise, a lower transition area between the end face 140 and the underside 132 of the working edge 130 is rounded.

The working edge 130 of the lamella doctor blade 100 is also surrounded by a coating 150. The coating 150 completely covers the upper side 131 of the working edge 130, the transition region 125 and a partial region of the upper side 121 of the rear region 120 of the base body 110 adjoining this. The coating 150 likewise covers the end face 140, the underside 132 of the working edge 130 and a partial region of the underside 122 of the rear region 120 of the base body 110 which adjoins the underside of the working edge 130.

The coating 150 is a polymer-based coating, for example the coating comprises epoxy resin, the epoxy resin content in the ready-to-use coating being, for example, approximately 70 or 80% by weight, depending on the side of the doctor blade (see below). Hard particles 160, e.g. B. from silicon carbide (SiC), dispersed. An average particle size of the hard material particles 160 is approximately 0.8 μm. The layer thickness of the first coating 150 measures z. B. 15 microns. In the area of the top side 121 and the bottom side 122 of the rear area 120, the layer thickness of the first coating 150 decreases continuously, so that the first coating 150 runs in a wedge shape in a direction away from the working edge 130.

The mass fraction of hard material particles 160 is higher in the coating on the first side of the doctor blade 100 facing the printing roller than in the coating on the second side of the doctor blade facing away from the printing roller. The first side comprises the front side 140 and the underside 132 of the working edge 130. The second side comprises the upper side 131 of the working edge 130. The mass fraction of hard material particles 160 in the coating of the first side is, for example, 20% by weight and the mass fraction of epoxy resin in the coating of the same side, for example 70% by weight. The mass fraction of hard material particles 160 in the coating on the second side is, for example, 10% by weight and the mass fraction in epoxy resin in the coating on the same side is, for example, 80% by weight. The second side of the doctor blade 100 thus has a lower content of hard material particles 160 than the first side of the doctor blade 100.

The first side, that is to say the side facing the printing roller 170, thus includes the contact area between the doctor blade 100 and the printing roller 170, specifically the end face 140. Furthermore, the first side also includes that surface 122 of the doctor blade which unites with a tangent in the contact area of the doctor blade Includes angle less than 90 °. The same interpretation applies to the following Figures 2 and 3 ,

Fig. 2 shows a second lamella doctor blade 200 according to the invention in cross section. The second lamella doctor blade 200 has a base body 210 with a rear region 220 and a working edge region 230 and is essentially identical in construction to the first lamella doctor blade 100 Fig. 1 , Likewise, in the case of the second squeegee doctor blade 200, the upper side 231 of the working edge 230, the transition region 225 and a partial region of the upper side 221 of the rear region 220 of the base body 210 adjoining this, as well as the front side 240, the lower side 232 of the working edge 230 and one on the lower side 232 the partial region of the underside 222 of the rear region 220 of the base body 210 adjoining the working edge 230 is coated with a coating 250.

The coating 250 in turn consists of a polymer-based coating, for example phenol-formaldehyde resin. The coating of the first side of the doctor blade 200 facing the printing roller comprises hard material particles 260, while the coating of the comprises no or essentially no hard material particles from the second side of the doctor blade facing away from the printing roller. The first side in turn comprises the front side 240 and the underside 232 of the working edge 230. The second side comprises the upper side 231 of the working edge 230. The hard material particles are, for example, cubic B ₄ C.

On the first side of the doctor blade 200, the ready-to-use coating has a phenol-formaldehyde resin content of, for example, 80% by weight. Furthermore, the coating on the first side comprises a cubic B ₄ C content of 15% by weight. The second side of the doctor blade 200 has a phenol-formaldehyde resin content of, for example, 95% by weight. The second side of the doctor blade 200 is essentially free of particles.

An average particle size of the hard material particles 260 is approximately 0.6 μm. The layer thickness of the first coating 250 measures z. B. 17 microns.

Fig. 3 shows a third lamella doctor blade 300 according to the invention in cross section. The third doctor blade 300 has a base body 310 which, in the region of the working edge 330, is made in the same way as the first doctor blade Fig. 1 is coated with a coating 350. The upper side 331 of the working edge 330, the transition region 325 and a partial area adjoining this, the upper side 321 of the rear area 320 of the base body 310, and the end face 340, the lower side 332 of the working edge 330 and a partial area adjoining the lower side 332 of the working edge 330 are correspondingly the underside 322 of the rear region 320 of the base body 310 coated with the coating 350.

In the third lamella doctor blade there is a coating 350 which completely surrounds the lamellar doctor blade 300. In other words, the coating 350 completely covers both the upper side 321 and the lower side 322 of the rear region 320 of the base body 310.

The coating 350 in turn consists of a polymer-based coating, for example polyamide. The coating of the first side of the pressure roller facing Doctor blade 300 comprises hard material particles 360, while the coating of the second side of the doctor blade facing away from the printing roller does not comprise, or essentially no, hard material particles. The first side in turn comprises the front side 340 and the underside 332 of the working edge 330. The second side comprises the top side 331 of the working edge 330. The hard material particles are, for example, tungsten particles.

On the first side of the doctor blade 300, the ready-to-use coating has a polyamide content of, for example, 85% by weight. Furthermore, the coating on the first side has a tungsten particle content of 8% by weight. The second side of the doctor blade 300 has a phenol-formaldehyde resin content of, for example, 93% by weight. The second side of the doctor blade 200 is again essentially free of particles.

An average particle size of the hard material particles 360 is approximately 0.3 μm. The layer thickness of the first coating 350 measures z. B. 12 microns.

The above and in the 1 - 3 The lamella doctor blade shown is only to be understood as illustrative examples of a large number of implementable embodiments.

Fig. 4 illustrates a method 400 for producing a lamellar squeegee, such as e.g. B. in Fig. 1 is shown. In a first step 401, the doctor blade is degreased electrolytically. The doctor blade 100 is switched as an anode for electrolytic degreasing in order to remove grease from the doctor body 110. Anodic electrolytic degreasing prevents hydrogen embrittlement. The doctor body 110 is then heated. In a second step 402, coating is carried out with the polymer-based coating material, in which the hard material particles and optionally further particles are dispersed and / or other auxiliaries are introduced. in the last step 403 there is a drying and curing step.

However, the above-described embodiments and the production method are only to be understood as illustrative examples, which can be modified as desired within the scope of the invention.

The base body 110, 210, 310 of the doctor blade can thus be made from the 1 - 3 also from another material, such as. B. stainless steel or a carbon steel. 3 In principle, the basic body of the doctor blade can be made from the 1 - 3 but also from a non-metallic material, such as. B. plastics exist. This can be particularly advantageous for applications in flexographic printing.

It is also possible to substitute in the 1 - 3 shown basic bodies to use each basic body with a different shape. In particular, the base body can have a wedge-shaped working edge or a non-tapered cross section with a rounded working edge. The free end faces 140, 240, 3403 of the working edges 130, 230, 330 can, for example, also be completely rounded.

Furthermore, the doctor blade according to the invention can be made from 1 - 3 be dimensioned differently. For example, the thicknesses of the working areas 130, 230, 330, measured from the respective upper sides 131, 231, 331 to the respective lower sides 132, 232, 332, can vary in a range of, for example, 0.040-0.200 mm.

The coatings of the doctor blade can also be made from the 1 - 3 further coating components and / or additional substances, such as. B. metal atoms, non-metal atoms, inorganic compounds and / or organic compounds. In particular, different lubricants or substances that influence the hardness of the coating can be provided. The additional substances can also be particulate.

All of the in the Figures 1-3 Squeegees shown can, for example, be coated with one or more further coatings. The other coatings can be in the area of the working edges and / or the rear areas and z. B. improve the wear resistance of the working edges and / or the rear area in front Protect influences from aggressive chemicals. Any further coating is preferably also polymer-based. In variants, however, other types of coating can also be used.

In summary, it can be stated that novel squeegees have been created which are characterized by good wear resistance and enable a uniform and streak-free wiping of printing ink over the entire service life and are also inexpensive to produce. At the same time, the doctor blade according to the invention can be implemented in a wide variety of embodiments, so that it can be specifically adapted to specific purposes.

Claims (17)

1. A squeegee (100), especially for squeegeeing printing ink off a printing cylinder, comprising a squeegee body (110) having a working edge (130) and a first squeegee side (122) which especially faces the printing cylinder in operation and a second squeegee side (121) which especially faces away from the printing cylinder in operation, where the squeegee body (110) has been provided with a coating (150) comprising a polymer, where the coating (150) comprises particles (160) at least in one subregion, and the particles (160) take the form of hard material particles (160), characterized in that a proportion by mass of the hard material particles (160) in the coating (150) on the first squeegee side (122) is higher than a proportion by mass of the hard material particles (160) in the coating (150) on the second squeegee side (121).
2. The squeegee (100) as claimed in claim 1, characterized in that the coating (150) of the first squeegee side (122) comprises hard material particles (160) and the coating (150) of the second squeegee side (121) is essentially free of hard material particles (160).
3. The squeegee (100) as claimed in claim 2, characterized in that the coating (150) of the second squeegee side (121) does not comprise any particles.
4. The squeegee (100) as claimed in any of claims 1 to 3, characterized in that an average volume-equivalent sphere diameter of the hard material particles (160) is less than 1'000 nanometers, preferably less than 500 nanometers, more preferably less than 250 nanometers.
5. The squeegee (100) as claimed in any of claims 1 to 4, characterized in that the hard material particles (160) comprise at least one of the following substances:

   a) metal oxides, especially aluminum oxide and/or chromium oxide;

   b) diamond;

   c) silicon carbide;

   d) metal carbide;

   e) metal nitride;

   f) metal carbonitride;

   g) boron carbide;

   h) cubic boron nitride;

   i) tungsten carbide.
6. The squeegee (100) as claimed in any of claims 1 to 5, characterized in that the squeegee body (110) has been formed from a metal or a metal alloy.
7. The squeegee (100) as claimed in claim 6, characterized in that the squeegee body (110) consists of steel.
8. The squeegee (100) as claimed in any of claims 1 to 5, characterized in that the squeegee body (110) has been formed from a plastic.
9. A process for producing a squeegee (100), especially a squeegee (100) as claimed in any of claims 1 to 8, where, in a squeegee body (110) with a working edge (130), a first squeegee side (122) which especially faces the printing cylinder in operation and a second squeegee side (121) which especially faces away from the printing cylinder in operation is coated with a coating (150) comprising a polymer and comprising particles (160) at least in one subregion, and the particles (160) take the form of hard material particles (160), characterized in that a proportion by mass of the hard material particles (160) in the coating (150) on the first squeegee side is higher than a proportion by mass of the hard material particles (160) in the coating (150) on the second squeegee side.
10. The process as claimed in claim 9, characterized in that the squeegee body (110) is heated prior to the coating.
11. The process as claimed in either of claims 9 and 10, characterized in that the squeegee body (110) is roughened prior to the coating.
12. The process as claimed in any of claims 9 to 11, characterized in that the squeegee body (110) is mechanically and/or electrolytically degreased prior to the coating.
13. The process as claimed in claim 11, characterized in that the squeegee (100) is connected as the anode for electrolytic degreasing in order to remove grease from the squeegee body (110) by means of cations.
14. The process as claimed in any of claims 9 to 13, characterized in that the coating of the squeegee body (110) with the coating (150) comprising a polymer is preceded by application of an adhesion coating.
15. The process as claimed in claim 14, wherein the application of the adhesion coating is followed and the coating of the squeegee body (110) with the coating (150) comprising a polymer is preceded by an intermediate drying step.
16. The process as claimed in any of claims 9 to 15, characterized in that the coating of the squeegee body (110) is followed by a drying step, where the drying step is especially followed by a hardening step.
17. The process as claimed in claim 16, characterized in that the hardening step is effected at a temperature of 150°C to 350°C, preferably at 200°C to 300°C, especially at 230°C to 270°C.

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