Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
  • C09D5/08—Anti-corrosive paints
  • C09D5/082—Anti-corrosive paints characterised by the anti-corrosive pigment
  • C09D5/086—Organic or non-macromolecular compounds
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F251/00—Macromolecular compounds obtained by polymerising monomers on to polysaccharides or derivatives thereof
  • C08F251/02—Macromolecular compounds obtained by polymerising monomers on to polysaccharides or derivatives thereof on to cellulose or derivatives thereof
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D4/00—Coating compositions, e.g. paints, varnishes or lacquers, based on organic non-macromolecular compounds having at least one polymerisable carbon-to-carbon unsaturated bond ; Coating compositions, based on monomers of macromolecular compounds of groups C09D183/00 - C09D183/16
  • C09D4/06—Organic non-macromolecular compounds having at least one polymerisable carbon-to-carbon unsaturated bond in combination with a macromolecular compound other than an unsaturated polymer of groups C09D159/00 - C09D187/00
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T156/00—Adhesive bonding and miscellaneous chemical manufacture
  • Y10T156/10—Methods of surface bonding and/or assembly therefor

Definitions

• the invention concerns a process for the coating of metallic surfaces with an organic anticorrosive composition, the anticorrosive composition and the coatings produced in such a way.
• pretreatment primer in industrial use, wherein a thin, e.g. 5 to 15 ⁇ m thick, paint film or a thin, paint-like organic film having elevated corrosion resistance is applied directly to the metallic surface without the application below it of a pretreatment coating or a similar coating, in particular for increasing paint adhesion and corrosion protection.
• DE-A1-196 23 268 describes a powder coating composition wherein a comparatively high content of an organic corrosion inhibitor is used together with an inorganic corrosion inhibitor.
• the object was therefore to propose an anticorrosive composition which is low in or free from water or organic solvent (so-called “100% system”) and which is of particularly high quality with regard to paint adhesion and corrosion protection or is even of such high quality that in many applications the interposition of a pretreatment coating can be dispensed with, for which reason in the latter case this anticorrosive composition can also be described as a pretreatment primer.
• the anticorrosive composition should if possible be able to be used for many purposes and on a mass scale and be as inexpensive as possible. It would be advantageous here to be able to reduce the content of particularly expensive corrosion inhibitors and other expensive components.
• the anticorrosive coating produced in this way should be readily formable together with the metallic substrate and with the at least one further paint film that is optionally additionally applied to it, and it should display good corrosion protection and good paint adhesion even after forming. It is desirable here that as many of these properties as possible are also obtained from thin films having a dry film thickness in the range from 4 to 12 ⁇ m in particular and optionally also, where the anticorrosive requirements are lower, having a dry film thickness in the range from 1 to 4 ⁇ m. It is also preferable if the anticorrosive composition is suitable for a high-speed coating of metallic strips.
• the anticorrosive composition should where possible be able to fulfil at least some of the following requirements, firstly as an anticorrosive coating applied on top of at least one pretreatment coat and secondly despite dispensing with all pretreatment coats, in each case as an organic thin-film coating having a dry film thickness in the range from 0.4 to 20 ⁇ m and preferably below 10 ⁇ m:
• the object is achieved with a process for coating surfaces of metallic substrates, in particular of parts, profiles or/and strips, preferably those based on aluminium, magnesium or/and steel, which are optionally precoated with at least one metallic coating such as e.g. a zinc layer or with at least one zinc-containing alloy layer, with an organic, anionically, cationically or/and radically curable anticorrosive composition, which is characterised in that the anticorrosive coating is a dispersion or solution
• the anticorrosive composition additionally contains at least one photoinitiator for anionic, cationic or/and radical crosslinking with a content in the range from 0.5 to 22 wt. %, if electron beam radiation is not used,
• additive(s) such as e.g. additives for substrate wetting such as in particular for bonding to electrodeposition coatings, wetting agents, defoaming agents, lubricants, bonding agents, pigments, flow control agents or/and agents to increase reactivity, surface additives to increase scratch resistance, thixotropic auxiliary agents,
• additives for substrate wetting such as in particular for bonding to electrodeposition coatings, wetting agents, defoaming agents, lubricants, bonding agents, pigments, flow control agents or/and agents to increase reactivity, surface additives to increase scratch resistance, thixotropic auxiliary agents,
• the anticorrosive composition is applied to the metallic surfaces in a wet film thickness in the range from 0.5 to 25 ⁇ m, optionally dried and is then anionically, cationically or/and radically cured to form an anticorrosive coating,
• the cured anticorrosive coating displays a dry film thickness in the range from 0.4 to 20 ⁇ m.
• the cured anticorrosive coating preferably displays a flexibility and bond strength of ⁇ T3, in particular of ⁇ T2 or even of ⁇ T1, determined by means of a T-bend test in accordance with ECCA standard T7 on hot-galvanised steel sheets of 0.3 mm thickness organically coated in a film thickness of 8 ⁇ m.
• the anticorrosive composition according to the invention is preferably a so-called 100% UV system, which is largely or entirely free from water or/and from organic solvent.
• Amounts of up to 5 wt. % water or/and of up to 5 wt. % organic solvent are preferred here, in particular amounts of up to 3 wt. % water or/and of up to 3 wt. % organic solvent, with amounts of up to 1 wt. % water or/and of up to 1 wt. % organic solvent being particularly preferred, because the time and effort required for drying are so much reduced and because the coating that is formed can—if necessary—be excited to cure and be cured by exposure to radiation more quickly or closer to the area in which the polymeric mixture is applied.
• a strip, for example, with the coating according to the invention can then—if necessary—be excited to cure and be cured by exposure to actinic radiation more quickly or closer to the area in which the anticorrosive composition is applied.
• UV curing is intended to include curing with any type of actinic radiation.
• Anionic, cationic or/and radical curing preferably takes place in the temperature range from 12 to 200° C., particularly preferably at 15 to 140° C., in particular at temperatures in the range from room temperature to 70° C.
• the coating mixture according to the invention can include a content of at least one compound forming free radicals under the influence of actinic radiation (so-called photoinitiator), wherein the total content of free-radical-forming compounds can in particular be in the range from 3 to 15 wt. %, relative to the dry matter. Their total content is preferably in the range from 4 to 14 wt. %, particularly preferably in the range from 5 to 13 wt. %, most particularly preferably in the range from 6 to 12 wt. %. In order to obtain the highest reactivities and MEK resistances, however, this range can be raised by up to 4 wt. %, in other words from 8 to 18 wt. %, for example.
• photoinitiator actinic radiation
• the at least one photoinitiator forms free radicals, which react with the radically polymerisable binder and crosslink it partially or completely during and possibly for a short period after actinic irradiation.
• the radically polymerisable compounds have unsaturated polymerisable groups which react with the groups formed from the photoinitiators due to radiation initiation and can form a water-insoluble network. After this chemical reaction this binder may still display reactive groups such as OH and polyol groups, which can limit the chemical resistance and corrosion resistance of the coating formed therefrom.
• the polymeric mixture is preferably made particularly reactive by means of elevated contents of at least one photoinitiator, in particular in order to obtain a fast(er) or/and as extensive a full cure as possible.
• adequate basic crosslinking is generally required.
• the radiation dosage can be increased or/and a more reactive anionically, cationically or/and radically curing polymer can be used. A high degree of crosslinking is quickly achieved in this way, and in particular also a full crosslinking.
• the anticorrosive composition preferably contains water or/and at least one organic solvent in a total content of only up to 2.5 wt. %, particularly preferably only up to 1.5 wt. %, most particularly preferably only up to 0.8 wt. %, in particular of less than 0.5 wt. %, above all of less than 0.3 or less than 0.15 wt. %, relative in each case to solids contents in wt. %.
• the total content of water or/and at least one solvent is preferably 0.02 to 4.5 wt. %, particularly preferably 0.025 to 4 wt. %, most particularly preferably at least 0.03 wt. % and up to 3.5 wt. %, in particular at least 0.05 wt.
• organic solvents are low-viscosity solvents not subject to labelling requirements, such as alcohols, or esters, ketones, glycol ethers or/and aromatic hydrocarbons, such as e.g. xylene, in particular propylene glycol ether.
• the anticorrosive composition prefferably be largely free from organic solvent. It is also preferable for almost no or no water or/and no organic solvent to be added separately to the anticorrosive composition and for such contents optionally only to be added in order to adjust the viscosity of the anticorrosive composition, for example. At least one of the raw material components conventionally contains a small or very small proportion of water or/and organic solvent.
• the liquid consistency of the anticorrosive composition according to the invention is preferably determined by the content, consistency and solubility characteristics of in particular the monomers or/and oligomers added for the polymers, which for that reason are also called reactive thinners. If a minimal amount of water or organic solvent is still present in the polymeric coating at the start of actinic irradiation, however, the formation of gas bubbles and the breaking up or/and warping of parts of the coating (known as blistering) can easily occur.
• compositions are therefore related to solids contents in wt. %, wherein contents of water or/and organic solvent exceed 100 wt. %.
• the anticorrosive coating according to the invention preferably also acts as a pretreatment coat, such that the adhesion to the substrate of a primer coating according to the invention and the corrosion resistance must be therefore correspondingly high in order to obtain at least adequate results even without the pretreatment coat.
• the anticorrosive coating when applied to the metallic substrate can preferably display a viscosity in the range from 80 to 20000 mPa ⁇ s, particularly preferably in the range from 150 to 15000 mPa ⁇ s, most particularly preferably in the range from at least 200 and up to 12000 mPa ⁇ s, in particular on metal strip in the range from 350 to 10000 mPa ⁇ s or in the range from 450 to 1200 mPa ⁇ s, measured at a temperature of 25° C. with a Haake VT 500 rotational viscometer with an MV DIN measuring cylinder in accordance with DIN 53019.
• the anticorrosive composition can display a temperature in the range from 5 to 90° C. when applied, particularly preferably in the range from at least 15, 20 or 25° C. to 70 or 60° C., in particular in the range from 20 to 50° C.
• the anticorrosive composition can preferably be applied to the metallic surface by pouring without or with a knife, spraying, atomisation, dipping or/and rolling.
• surfaces consisting of aluminium, aluminium-containing alloys, chromium, chromium alloys, magnesium alloys, stainless steels, steels, zinc, zinc-containing alloys, tin or/and tin-containing alloys can be coated.
• a metallic strip can be coated at a belt speed in particular in the range from 20 to 220 m per minute, wherein the application device for the coating mixture or/and the device for actinic irradiation of the polymeric coating can be held in a fixed position.
• many conveyor belt systems are operated at a speed in the range from 30 to 130 m/min. It is foreseeable, however, that in the future quite a few systems will be operated at a speed in the range from 80 to 200 m/min, in particular in the range from 100 to 180 m/min.
• Increasing the speed above 120 m/min in particular requires the reliable fulfilment of the particularly high demands on the system, on the automation of the process, on the quality of the mixtures used for coating and on process reliability.
• An elevated belt speed also requires particularly fast coating and crosslinking in order that the conveyor belt systems do not become too long.
• the wet film of the anticorrosive composition can be applied in particular in a film thickness in the range from 0.45 to 22 ⁇ m, preferably in the range from 0.5 to 18 ⁇ m, particularly preferably in the range from 0.6 to 14 ⁇ m, particularly preferably from at least 0.8 ⁇ m and up to 10 ⁇ m, above all from at least 1 ⁇ m and up to 8 ⁇ m.
• the wet film of the anticorrosive composition can be dried in particular at temperatures in the range from 30 to 95° C., particularly preferably in the range from 40 to 80° C., preferably by heating in an oven, inductive drying, IR irradiation, NIR (near infrared) irradiation or/and microwave irradiation.
• the largely or completely dry film of the anticorrosive composition can be irradiated, preferably with electron beam radiation, other short-wave high-energy radiation, visible radiation or/and UV radiation, the latter in particular in the wavelength range from 180 to 700 nm, particularly preferably with emission maxima in the wavelength range from 200 to 600 nm, and partially, extensively or completely crosslinked in this way, in particular anionically, cationically or/and radically crosslinked. Simultaneous cationic and radical crosslinking with UV radiation is also preferred. Lamps which emit substantially in the short-wave visible range from around 400 to 550 nm can also be used. UV light sources such as gas discharge lamps, xenon lamps or sodium vapour lamps are preferably used as radiation sources.
• the lamp power here is often in the range from 100 to in future over 300 Watts/cm, preferably currently in the range from 160 to 240 Watts/cm.
• Irradiation can optionally also be performed here with extensive or complete oxygen exclusion, allowing improved energy efficiency and faster belt speeds.
• Higher-energy radiation for example electron-beam radiation, can also be used in principle for curing.
• the actinic irradiation is preferably performed at ambient temperatures which are no higher or not substantially higher than room temperature, in other words generally no higher than around 65° C.
• the irradiated surface of the coating often reaches temperatures in the range from 50 to around 130° C. in this process due to UV excitation, which may display a proportion of IR radiation.
• polymerisation with at least one photoinitiator for anionic or/and cationic crosslinking, in particular for cationic crosslinking can take place.
• Anionic or/and cationic crosslinking is understood to be a polymerisation wherein the at least one suitable photoinitiator is activated and decomposed due to irradiation e.g. with IR light, NIR (near infrared) light, visible light or/and UV light and wherein the decomposition products react with anionically or/and cationically polymerisable substance and increase the chain lengths.
• Heat energy can optionally also be introduced in addition in support of cationic crosslinking in particular.
• Photoinitiators which can be used for this purpose are for example those such as diazonium, ferrocene, iodonium, sulfonium or/and thiapyrylium compounds, in particular salts—preferably aryl diazonium salts, diaryl iodonium salts, triaryl sulfonium salts—or those such as metallocene-like complex salts such as those based on a cyclopentadienyl compound, e.g.
• a cyclopentadienyl-aryl compound based on a cyclopentadienyl-aryl compound, and a fluorine complex containing boron, phosphorus, arsenic or antimony or based on a bis-cyclopentadienyl-iron derivative and e.g. a quinoid—which form Lewis or Brönsted acids under the influence of radiation.
• the presence of at least one sensitiser can be advantageous here.
• anionically or/and cationically polymerisable substances examples such as cyclic acetals, cyclic esters, cyclic ethers, cyclic organosiloxanes, cyclic sulfides, ethylene-unsaturated compounds, heterocyclic compounds, methylol compounds, vinyl monomers, vinyl prepolymers, epoxy resins or mixtures with at least one compound from these groups can be added, such as mixtures with aliphatic, cycloaliphatic, aromatic or/and heterocyclic epoxide, polyester, epoxidised polybutadiene, epoxy silanes, compounds containing epoxide groups, mixtures of epoxide with thermoplastic substance or epoxide-polyester mixtures, for example also epoxide group-containing monomers such as those based on glycidyl ethers of alcohols or epoxycyclohexyl derivatives.
• the content of photoinitiators for anionic or/and cationic crosslinking is in particular 0.1 to 5 wt. % of the content of anionically or/and cationically polymerisable substances, particularly preferably 0.8 to 3.5 wt. %. It is preferably in total 1 to 20 wt. % relative to the dry matter in the anticorrosive composition, particularly preferably 1.2 to 18 wt. % or 1.8 to 16 wt. %, most particularly preferably 3 to 15 wt. %, in particular at least 3.5 wt. % and up to 12 wt. %, above all at least 4 wt. % and up to 11 wt. %, above all at least 5 and up to 9 wt. %.
• the anticorrosive composition and the anionically, cationically or/and radically cured dry film produced therewith can contain at least one hardener for chemical crosslinking, such that the dry film, optionally after being heated to at least 60° C. or 80° C., is chemically postcured, preferably heated to temperatures in the range from 100 to 320° C., particularly preferably to temperatures in the range from 120 to 180° C.
• the substrate coated with the anticorrosive coating can be coated with at least one further paint-like composition, with lacquer, paint or/and adhesive.
• the anticorrosive coating applied to the metallic body can be formed with the substrate, in particular a metal sheet, wherein the anticorrosive coating remains largely or entirely undamaged, in spite of possibly extreme forming conditions.
• the formed substrate in the form of a formed, cut or/and stamped metal sheet coated with the anticorrosive coating can be joined to another construction element by gluing, welding or/and at least one other joining process.
• the metallic surface can be cleaned or/and pickled before application of the pretreatment primer coat and optionally rinsed thereafter at least once with water or an aqueous solution.
• the solution or dispersion can be applied to a metallic strip carried on a conveyor belt system, in particular to a strip coated with aluminium, with an aluminium-containing alloy or/and with at least one zinc-containing alloy, such as e.g. on the basis of AlSi, ZnAl such as Galfan®, AlZn such as Galvalume® or/and other Al alloys.
• the aluminium- or/and zinc-containing coating has only just been applied to the metallic strip on the same belt system, in other words generally just a few seconds or minutes earlier, this coating is particularly reactive, and if it is coated immediately with the anticorrosive composition according to the invention it produces far better values for adhesion and resistance to chemicals and impact than if this coating can first oxidise at its surface, is oiled, is coated in any other way or/and can be contaminated.
• the object is also achieved with a process for coating surfaces of metallic substrates—in particular of parts, profiles or/and strips, preferably those based on aluminium, magnesium or/and steel, which are optionally precoated with at least one metallic coating such as e.g. a zinc layer or with at least one zinc-containing alloy layer—with an organic, anionically, cationically or/and radically curing anticorrosive composition, which can also be characterised in that before coating with a first organic anticorrosive composition no pretreatment coat, such as e.g.
• this anticorrosive composition is a dispersion or solution which is applied directly to the metallic surfaces in a wet film thickness in the range from 0.4 to 25 ⁇ m—preferably from 0.6 to 15 ⁇ m, particularly preferably from 0.8 to 10 ⁇ m, in particular from 1 to 8 ⁇ m, optionally dried and then anionically, cationically or/and radically cured to form an anticorrosive coating, wherein the cured film displays a dry film thickness in the range from 0.4 to 20 ⁇ m—preferably from 0.6 to 18 ⁇ m, particularly preferably from at least 0.8 and up to 12 ⁇ m, in particular from at least 1 and up to 8 ⁇ m, wherein the anticorrosive coating preferably achieves a flexibility and bond strength of ⁇ T3, in particular of ⁇ T2 or even of ⁇ T1, determined by means of a T-bend test in accordance with EC
• an organic, anionically, cationically or/and radically curable anticorrosive composition which is characterised in that it is a dispersion or solution containing at least two components selected from the group of monomers, oligomers and polymers which are at least partially anionically, cationically or/and radically curable and are included in a content in the range from 50 to 95 wt. %,
• a content of at least one monofunctional monomer or/and oligomer in the range from 1 to 58 wt. % is included herein and
• the anticorrosive composition contains at least one photoinitiator for anionic, cationic or/and radical crosslinking with a content in the range from 0.5 to 22 wt. %, if electron beam radiation is not used,
• At least one hardener with a content in the range from 0.05 to 8 wt. % for a chemical postcure
• additive(s) such as e.g. additives for substrate wetting such as in particular for bonding to electrodeposition coatings, wetting agents, defoaming agents, lubricants, bonding agents, pigments, flow control agents, agents to increase reactivity, surface additives to increase scratch resistance or/and thixotropic auxiliary agents,
• additives for substrate wetting such as in particular for bonding to electrodeposition coatings, wetting agents, defoaming agents, lubricants, bonding agents, pigments, flow control agents, agents to increase reactivity, surface additives to increase scratch resistance or/and thixotropic auxiliary agents,
• Monomers and oligomers, oligomers and polymers, monomers and polymers or monomers, oligomers and polymers are included in the anticorrosive composition, wherein the content of such compounds, which are anionically, cationically or/and radically curable, is in particular at least 40 wt. %, particularly preferably at least 44 wt. %, most particularly preferably at least 48 wt. %, above all preferably at least 52 wt. %, in particular at least 56 wt. % and in particular up to a maximum of 92 wt. %, particularly preferably a maximum of 88 wt. %, most particularly preferably a maximum of 84 wt.
• the content of such compounds including photoinitiators, which are anionically, cationically or/and radically curable or curing, is in particular at least 45 wt. %, particularly preferably at least 50 wt. %, most particularly preferably at least 55 wt. %, above all preferably at least 60 wt. % and in particular up to a maximum of 99 wt. %, particularly preferably a maximum of 94 wt. %, most particularly preferably a maximum of 88 wt. %, above all preferably a maximum of 82 wt. %.
• the process according to the invention or the anticorrosive composition according to the invention can also be characterised in that at least two components selected from the group of monomers, oligomers and polymers which are at least partially anionically, cationically or/and radically curable are added to the anticorrosive composition, wherein the content of monomers is in the range from 0 to 60 wt. %, the content of oligomers is in the range from 0 to 60 wt. % and a polymer content is optionally also necessary, wherein the content of polymers can be in the range from 10 to 70 wt. %, wherein on the one hand at least one monomer or/and at least one oligomer and in other embodiments also at least one polymer is present.
• the molecular weight of the added monomers is often in the range up to 500, advantageously in the range from 100 up to 350.
• the molecular weight of the oligomers is advantageously in the range from 300 up to 20000.
• the content of monomers is particularly preferably in the range from 1 to 58 wt. %, most particularly preferably over 16 and less than 52 wt. %, in particular over 22 and less than 44 wt. %; the content of oligomers is particularly preferably in the range from 1 to 58 wt. %, most particularly preferably over 16 and less than 52 wt. %, in particular over 22 and less than 44 wt. %;
• the content of polymers is particularly preferably in the range from 15 to 60 wt.
• At least one base polymer based on acrylate, epoxide, methacrylate, polyester, polyurethane or/and copolymers thereof can preferably be added to the anticorrosive composition, in particular epoxy acrylate, polyester acrylate, urethane acrylate or/and mixtures thereof having a different basic chemistry or/and different molecular weights.
• the base polymer serves to provide a good polymeric anticorrosive base. All polymers which within the context of this application are not classed as optionally modified flexibilising resins and not as coupling polymers are classed within the context of this application as base polymers.
• the base polymer can optionally be aliphatically modified and optionally made more flexible as a result. It is preferable that all oligomers and polymers used, optionally even including the added monomers, do not display a tendency to become brittle.
• oligomers or/and polymers are advantageously copolymerisable or/and copolymerised.
• the acid values of the added monomers, oligomers or/and polymers are in particular in the range from 1 to 5 mg/g KOH, measured in accordance with DIN 53402.
• the pH values of the added monomers, oligomers or/and polymers are in particular in the range from 4 to 9, particularly preferably in the range from 5 to 8.
• the process according to the invention can also be characterised in that monomers or/and oligomers based on unsaturated, optionally aliphatic or/and aromatic compounds, such as those based on unsaturated aliphatic acrylates for example, are added to the anticorrosive composition.
• monomers or/and oligomers based on unsaturated, optionally aliphatic or/and aromatic compounds, such as those based on unsaturated aliphatic acrylates for example are added to the anticorrosive composition.
• Particularly advantageous here are monofunctional, difunctional or/and trifunctional monomers or/and oligomers, but above all monofunctional compounds.
• it can be ensured that a medium-sized crosslinking density and a narrow distribution of medium-sized chain lengths are achieved when these components are crosslinked.
• isobornyl acrylate or/and isobornyl methacrylate is in particular 16 to 45 wt. %, above all 28 to 42 wt. %.
• Monofunctional compounds are particularly preferred because they generally do not have a negative influence on elasticity.
• Difunctional compounds such as e.g. 2-ethylhexyl acrylate or/and dipropylene glycol diacrylate are conventionally good solvents for polymers and are therefore suitable for adjusting the viscosity of systems which are largely or entirely free from water or/and organic solvents.
• Trifunctional compounds such as e.g.
• the total content of difunctional monomers or/and difunctional oligomers, if used, is preferably in the range from 3 to 30 wt. %, particularly preferably at least 6 and less than 22 wt. %, most particularly preferably at least 12 and less than 16 wt. %.
• the proportion of monofunctional or/and difunctional monomeric or/and oligomeric compounds in the anticorrosive composition is in particular at least 10 wt. %, particularly preferably at least 20 wt. %, most particularly preferably at least 30 wt. %, above all preferably at least 35 wt. %, in particular at least 40 wt. %, especially at least 42 wt. % and in particular up to 62 wt. %, particularly preferably up to 56 wt. %, most particularly preferably up to 50 wt. %.
• the proportion of polymeric compounds in the anticorrosive composition is preferably at least 20 wt. %, particularly preferably at least 24 wt. %, most particularly preferably at least 28 wt. %, above all preferably at least 30 wt. %, in particular at least 32 wt. % and in particular up to 62 wt. %, particularly preferably up to 56 wt. %, most particularly preferably up to 50 wt. %.
• the content of the at least one monofunctional monomer or/and at least one monofunctional oligomer is preferably 1 to 66 wt. %, particularly preferably 10 to 58 wt. %, most particularly preferably at least 20 wt. % and up to 52 wt. %, in particular at least 28 wt. % and up to 48 wt. %, above all at least 34 wt. % and up to 44 wt. %.
• the process according to the invention can also be characterised in that at least one anionically, cationically or/and radically polymerisable monomer or/and oligomer is added to the anticorrosive composition, selected from the group of compounds based on acrylate or/and methacrylate, preferably those based on benzyl, butyl, diol, diacrylate, ethyl, formal acrylate, glycol, hexyl, isobornyl, methyl, propyl or/and styrene, in particular those selected from the group comprising butanediol diacrylate, diethylene glycol diacrylate DEGDA, dipropylene glycol diacrylate DPGDA, 2-ethylhexyl acrylate EHA, hexanediol dicyl acrylate HDDA, hydroxypropyl methacrylate HPMA, isobornyl acrylate IBOA, isobornyl methacrylate IBOMA, polyethylene
• At least one flexibilising resin or/and at least one modified flexibilising resin can additionally be added to the anticorrosive composition as oligomers or/and polymers, in particular at least one based on unsaturated aliphatic polymers such as e.g. those based on acrylate, methacrylate, polyester or/and polyurethane, in particular based on acrylate, methacrylate or/and polyurethane. It can be dissolved in at least one monomer or/and oligomer. In this way they obtain a favourable viscosity for processing.
• An anionically, cationically or/and radically polymerisable, optionally modified flexibilising resin can substantially help to produce a particularly flexible dry film.
• the optionally modified flexibilising resin is preferably characterised in that when used without the addition of other substances apart from at least one photoinitiator and optionally at least one monomer to dissolve the flexibilising resin, it gives rise to a cured coating which displays a particularly high flexibility determined as elongation at break, in particular an elongation at break of at least 200, 250, 300, 350 or 400% of the initial length.
• the modification can be carried out with acrylic groups, for example. It is therefore advantageous to add a total content thereof in the range from 0.1 to 30 wt. %, in particular at least 0.8 wt. % and at most 22 wt. %, particularly preferably at least 1.5 wt. % and at most 15 wt. %, most particularly preferably at least 2 wt. % and at most 8 wt. %.
• the anticorrosive composition can be selected in terms of double bonds of the oligomers or/and polymers and the content of monomers, oligomers or/and polymers and in terms of the duration, intensity and wavelength of the actinic radiation such that—in particular with monomers, oligomers or/and polymers displaying double bonds or/and unsaturated groups—a polymeric network having a medium-sized distance between crosslinking points is formed which at the same time has high flexibility and high chemical resistance, such that the crosslinked coating that is formed displays a T-bend flexibility of at least T ⁇ 2, in particular T ⁇ 1.
• At least one photoinitiator for radical crosslinking can advantageously be added to the anticorrosive composition, based on compounds selected from the group comprising alkyl benzoyl formates, amino ketones, benzoin ethers, benzophenones, dimethyl ketals, glyoxylates, hydroxyketones, hydroxyphenones, isopropyl ethers, metallocenes, organic iodine compounds, phenyl ketones, phenyl propanes and phosphine oxides or/and at least one photoinitiator for anionic or/and cationic crosslinking based on compounds selected from the group comprising protonic acids, Lewis acids and Friedel-Crafts catalysts and carbonium ion salts—in particular at least one dispersion or/and solution—and optionally at least one crosslinking agent for a chemical postcure, in particular at least one capped hardener.
• the crosslinking agents are above all those based on isocyanate, isocyanurate, melamine resin or/and compounds which can release isocyanate or isocyanurate at elevated temperature, such as TDI, MDI, HDMI or/and HDI, for example. These can be based for example on 2,4- or 2,6-toluene diisocyanate (TDI), 4,4′-methylene di(phenyl)-isocyanate (MDI) or hexamethylene diisocyanate (HDI). Compounds forming free radicals under the influence of actinic radiation are suitable in principle as photoinitiators for the radical crosslinking.
• TDI 2,4- or 2,6-toluene diisocyanate
• MDI 4,4′-methylene di(phenyl)-isocyanate
• HDI hexamethylene diisocyanate
• the use of particularly reactive photoinitiators is recommended, particularly if coating is to be performed on a conveyor belt at a speed of over 40 m/min, in order to ensure an adequate anionic, cationic or/and radical polymerisation in a very short time.
• An anionic, cationic or/and radical polymerisation can be described as adequate in particular if over 60 MEK cycles are successfully withstood during solvent resistance testing.
• At least one postcuring compound such as e.g. at least one ETL binder, particularly preferably at least one water-soluble or/and water-dispersible polymerisable postcuring compound, is also added to the anticorrosive composition in order to allow an anionic, cationic or/and radical cure and subsequently or/and later in conjunction with at least one hardener a chemical postcure, which is preferably initiated or/and intensified by heating.
• the total content of the at least one postcuring compound can in particular be 0.3 to 30 wt. %, relative to the dry matter. Its total content is preferably in the range from 1 to 25 wt. %, particularly preferably in the range from 1.5 to 20 wt.
• postcuring can extend over a number of days and can be accelerated by raised temperature or/and in the presence of a catalyst for the postcuring compound, such as e.g. dibutyl tin laurate (DBTL).
• DBTL dibutyl tin laurate
• capped binders are used, however, capping must first be terminated chemically at around at least 80° C. before thermal crosslinking can take place.
• preferred postcuring compounds include isocyanates and isocyanurates, which conventionally act as hardeners or crosslinking agents. These can be based for example on 2,4- or 2,6-toluene diisocyanate (TDI), 4,4′-methylene di(phenyl)isocyanate (MDI) or hexamethylene diisocyanate (HDI).
• TDI 2,4- or 2,6-toluene diisocyanate
• MDI 4,4′-methylene di(phenyl)isocyanate
• HDI hexamethylene diisocyanate
• Isocyanates and isocyanurates based on HDI or/and TDI are preferably used.
• the postcuring compounds react with the free OH and polyol groups in the UV-curing resin to form polyureas, which are known to be highly resistant compounds, and related chemical compounds.
• Suitable as crosslinking agents for a chemical postcure are in particular aliphatic or/and aromatic isocyanates and isocyanurates, in the case of capped hardeners in particular aliphatic or/and aromatic isocyanates and isocyanurates.
• the content of the at least one, optionally capped, hardener for chemical postcuring is preferably 0.8 to 9 wt. %, particularly preferably 1.2 to 6 wt. %, most particularly preferably at least 1.5 wt. % and up to 4 wt. %, in particular at least 1.8 wt. % and up to 3.6 wt. %.
• the ratio of all binders without crosslinking agent to all crosslinking agents for chemical crosslinking and postcuring, including photoinitiators for anionic, cationic or/and radical crosslinking is preferably 60:40 to 92:8, particularly preferably 65:35 to 88:12, particularly preferably at least 70:30 and up to 85:15.
• the ratio of all binders without crosslinking agent to all crosslinking agents for chemical postcuring is preferably 80:20 to 95:5, particularly preferably 85:15 to 92:8, particularly preferably at least 88:12 and up to 90:10.
• the ratio of all base polymers to all flexibilising resins including modified flexibilising resins is preferably 80:20 to 95:5, particularly preferably 82:18 to 92:8, particularly preferably at least 6:1 and up to 8:1.
• the ratio of all base polymers to all anionically, cationically or/and radically curable monomers and oligomers is preferably 90:10 to 35:65, particularly preferably 80:20 to 45:55, particularly preferably at least 45:55 and up to 60:40.
• the ratio of all anionically, cationically or/and radically curable polymers without crosslinking agent to all anionically, cationically or/and radically curable monomers and oligomers without crosslinking agent is preferably 25:75 to 80:20, particularly preferably 32:68 to 65:35, particularly preferably at least 40:60 and up to 50:50.
• Particularly preferable inter alia are alkyl aminoethanols such as dimethyl aminoethanol and complexes based on a TPA amine such as N-ethyl morpholine complex with 4-methyl- ⁇ -oxo-benzenebutanoic acid.
• the first organic corrosion inhibitor can be added in order to bring about a greater corrosion inhibition or further to intensify it. It is particularly advantageous if ungalvanised steel surfaces, in particular cold-rolled steel (CRS), are to be coated.
• At least one further organic or/and inorganic corrosion inhibitor can advantageously be added to the anticorrosive composition
• the at least one inorganic corrosion inhibitor can be selected from the group based on anticorrosive pigments and compounds based on titanium, hafnium, zirconium, carbonate or/and ammonium carbonate, wherein the anticorrosive pigments are preferably those based on silica(s), oxide(s) or/and silicates, such as e.g. alkaline-earth-containing anticorrosive pigment(s), based in particular on calcium-modified silica or silicate pigment.
• the content of the at least one further organic or/and inorganic corrosion inhibitor is preferably 0.1 to 16 wt.
• Siliceous pigments are particularly preferred when they buffer the hydrogen ions in the coating mixture and thereby prevent the onset of corrosion.
• the coating mixture according to the invention can preferably contain at least one anticorrosive pigment, wherein the total content of anticorrosive pigment in some embodiments can preferably be in the range from 0.1 to 15 wt. %, particularly preferably in the range from 0.5 to 10 wt. %, most particularly preferably in the range from 1.2 to 8 wt. %, relative to the solids content. In other embodiments the total content of anticorrosive pigment is preferably in the range from 0.1 to 8 wt. %, particularly preferably in the range from 0.5 to 6.5 wt. %, most particularly preferably in the range from 1 to 5 wt. %.
• anticorrosive pigments those based on at least one oxide, phosphate or/and silicate can be used in particular.
• Modified silica pigments and siliceous pigments, frequently as colloidal pigments, are often particularly preferred, because they can buffer the hydrogen ions in the coating mixture and therefore still further delay the onset of corrosion.
• the anticorrosive composition according to the invention preferably contains at least one pigment such as e.g. at least one coloured pigment or/and at least one anticorrosive pigment, wherein within the context of this application the anticorrosive pigments are assigned to the corrosion inhibitors and the other pigments are classed as additives.
• at least one pigment such as e.g. at least one coloured pigment or/and at least one anticorrosive pigment, wherein within the context of this application the anticorrosive pigments are assigned to the corrosion inhibitors and the other pigments are classed as additives.
• the coating mixture according to the invention should include no content or the lowest possible content—in total preferably no more than 5 wt. %—of pigment having a moderately high or high absorption in the spectral range of the chosen actinic radiation or/and light type which is used for anionic, cationic or/and radical crosslinking, in particular UV radiation.
• the coating mixture according to the invention can preferably contain up to 20 wt.
• the total content of pigments without anticorrosive pigments is preferably in the range from 1 to 12 wt. %, particularly preferably in the range from 2 to 10 wt. %, most particularly preferably in the range from 3 to 8 wt. %. This is because often only the addition of a comparatively low content of anticorrosive pigment or other pigment is advantageous.
• the anticorrosive composition according to the invention is ideally suited for the addition of pigment types other than anticorrosive pigments, e.g. coloured pigments or hard materials such as e.g. isometric or more or less spherical pigments or hollow-particle powders.
• the total content of the at least one additive is preferably 1.2 to 12.5 wt. %, particularly preferably 1.8 to 10 wt. %, most particularly preferably at least 2.5 wt. % and up to 9 wt. %, in particular at least 3.5 wt. % and up to 8 wt. %.
• a high content of coloured or/and white pigments can cause these ranges to be shifted by absolute values of 10 or even 15 or 20 wt. %, however.
• the content of the at least one additive can preferably be 10 to 32.5 wt. %, particularly preferably 13 to 30 wt. %, most particularly preferably at least 16 wt. % and up to 28 wt. %, in particular at least 18 wt. % and up to 26 wt. %.
• the coating mixture according to the invention can contain at least one of the below-mentioned additives such as e.g. wetting agents such as those based on e.g. lecithin oil, silane(s), siloxane(s), other oil or/and defoaming agents such as e.g. those based on mineral oil(s), polysiloxane(s) or/and derivatives thereof such as e.g. copolymers, surface additives to increase scratch resistance, such as e.g. those based on silane(s), siloxane(s) or/and wax dispersion(s), additives for substrate wetting such as e.g.
• wetting agents such as those based on e.g. lecithin oil, silane(s), siloxane(s), other oil or/and defoaming agents such as e.g. those based on mineral oil(s), polysiloxane(s) or/and derivatives thereof such as e.g. copo
• a wetting agent provides a homogeneous wetting for the substrate or to overcome the varying surface tension between different films.
• a defoaming agent ensures that as few air bubbles as possible are trapped in the applied coating so that no pores are formed in it.
• a flow control agent helps to form a homogeneous surface and in particular to prevent a rolling texture or/and orange-peel effect.
• the total content of all additives can in particular be in the range from 0.05 to 22 wt. %, relative to the solids content. Their total content is preferably in the range from 0.3 to 20 wt. %, particularly preferably in the range from at least 1 and up to 17.5 wt. %, most particularly preferably in the range from at least 2 and up to 15 wt. %.
• the coating mixture according to the invention can contain at least one lubricant, such as e.g. at least one based on graphite, polyethylene, polypropylene such as on the basis of polyethylene oxide or polypropylene oxide, polytetrafluoroethylene (PTFE), other types of waxes, silane, siloxane such as dimethyl siloxane or/and derivatives thereof, selected in particular from crystalline microwax(es), silane(s) or/and polysiloxane(s), wherein the total content of lubricant can in particular be in the range from 0.05 to 5 wt. %, relative to the solids content. Their total content is preferably in the range from 0.2 to 4 wt.
• lubricant such as e.g. at least one based on graphite, polyethylene, polypropylene such as on the basis of polyethylene oxide or polypropylene oxide, polytetrafluoroethylene (PTFE), other types of waxes, silane, siloxan
• lubricant should be chosen so that the surfaces treated in this way can subsequently optionally also be printed, overpainted, glued or coated by other means.
• At least one coupling polymer can preferably additionally be added to the anticorrosive composition, in particular at least one based on amine such as tertiary amine, phosphoric acid esters or/and other phosphor-containing acids such as phosphonic acids, in particular those for example with polymers based on acrylate, epoxide, methacrylate, polyester, polyurethane or/and copolymers thereof or as monoesters, diesters or/and triesters thereof. It is therefore advantageous to add a total content thereof in the range from 1 to 20 wt. %, in particular at least 7 wt. % and at most 14 wt. %.
• the anticorrosive composition can contain as additive at least one pigment selected from the group of compounds based on coloured pigment, metal pigment, oxide, phosphate, phosphide, phosphosilicate, silicate, electrically conductive pigment and coated pigment or/and selected from the group comprising aluminium, aluminium alloys, iron alloys, iron hydroxide, iron oxide, iron phosphate, iron phosphide, graphite, silica, modified silica, optionally modified aluminium silicate, alkaline earth silicate or alumosilicate, hypostoichiometric electrically conductive oxide, carbon black, zinc and more highly corrosion-resistant aluminium- or/and zinc-containing alloy.
• at least one pigment selected from the group of compounds based on coloured pigment, metal pigment, oxide, phosphate, phosphide, phosphosilicate, silicate, electrically conductive pigment and coated pigment or/and selected from the group comprising aluminium, aluminium alloys, iron alloys, iron hydroxide, iron oxide, iron phosphate, iron
• the coating mixture according to the invention and the coating produced from it are preferably free or largely free from environmentally damaging chromate. They are preferably free or largely free from heavy metals such as chromium, cobalt, copper or/and nickel, for example. They are frequently free from colouring components and will then display little or no colour—even as a cured polymeric coating. It is preferable to produce a polymeric coating which as far as possible is colourless, clear or at least transparent. For certain applications it can be desirable, however, to produce anticorrosive coatings coloured with dyes or/and pigments.
• the anticorrosive composition preferably contains the following contents, wherein not all of the listed components or groups of compounds need to be added: a) Anionically, cationically or/and radically curing 50-99 wt. % components: Base polymer(s) 10-45 wt. % Flexibilising resin(s), optionally modified 1-25 wt. % Monomer(s) and oligomer(s) 5-65 wt. % of which monofunct. monomers + olig. 5-55 wt. % of which difunct. monomers + oligomers 1-55 wt. % of which trifunct. monomers + oligomers 5-55 wt. % Photoinitiator(s) 1-20 wt.
• Lubricant 0.1-5 wt. % Coupling polymer 1-18 wt. % Bonding agent 1-18 wt. % Pigments, excl. anticorrosive pigm. 0.1-18 wt. % Thixotropic aux. agent 0.1-5 wt. % Flow control agent 0.1-3 wt. % Add. to increase scratch resistance 0.1-2 wt. % Add. to increase reactivity 0.1-5 wt. % Add. for substrate wetting 0.1-2 wt. % e) Solvent: 0.01-5 wt. % Water 0.01-5 wt. % Organic solvent(s) 0.01-5 wt. %
• the anticorrosive composition particularly preferably contains the following contents, wherein not all of the listed components or groups of compounds need to be added: a) Anionically, cationically or/and radically curing 60-98 wt. % components: Base polymer(s) 20-40 wt. % Flexibilising resin(s), optionally mod. 2-20 wt. % Monomer(s) and oligomer(s) 10-48 wt. % of which monofunct. monomers + olig. 10-50 wt. % of which difunct. monomers + olig. 10-50 wt. % of which trifunct. monomers + olig. 10-50 wt. % Photoinitiator(s) 2-18 wt.
• Lubricant 0.1-1.5 wt. % Coupling polymer 3-14 wt. % Bonding agent 3-14 wt. % Pigments, excl. anticorrosive pigm. 0.1-14 wt. % Thixotropic aux. agent 0.1-4 wt. % Flow control agent 0.1-2 wt. % Add. to increase scratch resistance 0.1-1.5 wt. % Add. to increase reactivity 0.1-4 wt. % Add.for substrate wetting 0.1-1.5 wt. % e) Solvent, if added: 0.01-4 wt. % Water 0.01-3 wt. % Organic solvent(s) 0.01-3 wt. %
• the anticorrosive composition most particularly preferably contains the following contents, wherein not all of the listed components or groups of compounds need to be added: a) Anionically, cationically or/and radically curing 70-97 wt. % components: Base polymer(s) 25-35 wt. % Flexibilising resin(s), optionally mod. 3-10 wt. % Monomer(s) and oligomer(s) 30-45 wt. % of which monofunct. monomers + olig. 20-45 wt. % of which difunct. monomers + olig. 10-45 wt. % of which trifunct. monomers + olig. 10-45 wt.
• the object is also achieved with an organic, anionically, cationically or/and radically cured anticorrosive coating on a metallic substrate which displays a dry film thickness in the range from 0.4 to 20 ⁇ m and which can also be characterised in that
• a corrosion resistance when applied directly to a metallic surface, without the interposition of a pretreatment coat, it displays a corrosion resistance, tested as subsurface migration at a scratch, of ⁇ 5 mm, ⁇ 4 mm, ⁇ 3 mm, ⁇ 2 mm or ⁇ 1 mm, determined in particular in a salt spray test SS to DIN 50021 at 35° C. for at least 150 h or for at least 200 h, preferably at least 200 h, at least 250 h, at least 300 h, at least 350 h, at least 400 h, at least 450 h or even at least 500 h, wherein the anticorrosive coating remains free from blisters,
• an organic cured anticorrosive coating on a metallic substrate displays a dry film thickness in the range from 0.1 to 20 ⁇ m or from 0.4 to 20 ⁇ m and a chemical resistance of over 50 MEK cycles—the latter determined in the MEK test in accordance with ECCA standard T 11 with methyl ethyl ketone—and it displays an elasticity and bond strength in the indentation test according to DIN EN ISO 1520 with a ball indentation of at least 6 mm, preferably at least 6.5 mm, particularly preferably at least 7, 7.5 or 8 mm, preferably tested with a sheet thickness of 0.75 mm relative to the perfect appearance, or/and
• a chemical resistance of over 20 MEK cycles can already be regarded as very high.
• 20 MEK cycles are unknown for such chemical systems, which nevertheless contain significantly more than a total of 5 wt. % water or/and organic solvent.
• 20 to 100 MEK cycles can only be achieved with a very high reactivity of the chemical system.
• the crosslinkability and the MEK cycle count can be taken as indicators of this.
• the exceptionally high performance of the coatings according to the invention is also signalled by the fact that not only an unusually high chemical resistance but also in many cases a very high flexibility and bond strength is achieved at the same time.
• the coating according to the invention can be overpainted repeatedly with any thermally curing paint system. Coloured paints in particular are especially suitable. Due to the conventionally very long-lasting corrosion resistance, this coating is particularly suitable for the production of painted architectural applications as in structural steels, for example.
• the anticorrosive composition according to the invention Due to the use of the anticorrosive composition according to the invention it is possible not only to dispense with the at least one pretreatment coat which nowadays is always applied below a first paint coat or paint-like coat but also to omit the at least one rinsing and the at least one re-rinsing solution or at least one drying which is commonly additionally used, without compromising on quality.
• the anticorrosive composition according to the invention is astonishingly inexpensive.
• the substrates coated according to the invention can be used in particular in the steel industry, in automotive construction or/and in aircraft construction, in particular in standard car production, as wire, wire winding, wire mesh, sheet metal, cladding, screening, car body or car body part, part of a vehicle, trailer, caravan or flying body, covering, housing, lamp, light, traffic light element, item of furniture or furniture element, element of a domestic appliance, frame, profile, moulding with complex geometry, crash barrier element, radiator element or fencing element, bumper, part consisting of or having at least one pipe or/and one profile, window, door or bicycle frame or as a small component such as e.g. a screw, nut, flange, spring or spectacle frame.
• the anticorrosive coating produced according to the invention can be used in particular as a protective coating in forming or/and joining, as corrosion protection for surfaces or in the vicinity of edges, seams or/and weld seams, as protection in place of cavity sealing or/and seam sealing, in particular for vehicle construction or aircraft construction.
• the steel sheets coated according to the invention in particular those produced on the conveyor belt, were outstandingly suitable for being formed together with the thin anticorrosive coating according to the invention to produce faultless corrugated sheet, for example, including the U-shaped profile at the edge of the corrugated sheet.
• the present application also provides organic anticorrosive coatings in general on metallic substrates, wherein the coatings display a dry film thickness in the range from 0.4 to 20 ⁇ m and a chemical resistance of over 100 MEK cycles, determined in the MEK test in accordance with ECCA standard T11 with methyl ethyl ketone.
• This chemical resistance is obtained in particular with an elasticity and bond strength determined in the indentation test to DIN EN ISO 1520 with a ball indentation of at least 6 mm.
• Binders in the form of mixtures were predominantly used. Binders, monomers, corrosion inhibitors, photoinitiators and additives were first mixed together according to the examples in Table 1.
• 1.a, 1.b and 1.d are used as base polymers, 1.c as flexibilising resin, 1.e as hardener for chemical postcuring, 2.a and 2.b as monofunctional monomers, 2.c to 2.i as difunctional or multifunctional monomers and 3.a as bonding agent, 3.b and 3.c as lubricants, 3.d as wetting agent or/and 3.e as co-initiator to increase the reactivity.
• the proportion of monomers added at the start was only 85 to 90 wt. % of the amounts given in Table 1.
• hot-galvanised steel sheets of thickness 0.3 mm were used, which had not been provided with a pretreatment coat.
• the coating mixture according to the invention was applied by knife application and on a laboratory coater or by spraying in a wet film thickness of 7 to 9 ⁇ m. A maximum nozzle diameter of 1 mm was used for spraying. There was no need to dry the coated sheets since there was virtually no solvent content.
• the polymeric coating was cured twice in immediate succession at room temperature with an Hg-doped UV lamp in the wavelength range between 200 and 300 nm at a power of 120 W/cm at a belt speed of 5 m/min, producing an irradiation of approx. 15 cm in the direction of belt travel.
• the dry films produced in this way had a film thickness in the range from 7.6 to 8.4 ⁇ m.
• the flexibilising resins were advantageously already pre-dissolved in IBOA or/and IBOMA, which allowed a very high elongation at break to be obtained.
• the elongation at break was measured in accordance with DIN 53504 on free organic cured films clamped in a tensile testing machine, extended and broken at room temperature, wherein the extension at the moment of break was measured as a % of the original length: this even produced values of at least 300% when only one photoinitiator was added to the pre-dissolved flexibilising resin and when this mixture was applied and cured.
• composition of the coating mixtures according to the invention is given in Table 1, the viscosities and properties of the coatings are set out in Table 2.
• Table 1 the viscosities and properties of the coatings are set out in Table 2.
• both variants without and also one with an additional postcuring compound were tested.
• a standard industrial stoving enamel was applied to metal sheets produced in the same way and baked in order to test a two-coat structure; in comparison to the single coating composition the results were not significantly other than expected, however, for which reason the associated properties are not listed separately.
• the corrosion protection was improved by the thicker paint film structure and in some cases the flexibility or/and elasticity was slightly reduced.
• the content of binders based on at least one polyester urethane acrylate, at least one modified polyester urethane acrylate or/and at least one urethane acrylate is preferably 25 to 37 wt. %, particularly preferably 27 to 35 wt. %, in particular at least 28 wt. % and in particular up to 34 wt. %.
• the content of radical binders including chemical postcuring agents is preferably 25 to 41 wt. %, particularly preferably 27 to 39 wt. %, in particular at least 28 wt. % and in particular up to 37 wt. %.
• T1 denotes the single thickness
• T2 the double thickness etc. of the metal strip used as a measure for the diameter and the distance between the metal strips bent into a U shape with parallel faces
• a bending radius of e.g. T1 to T4 is set depending on the flexibility of the top coat in the case of topcoated sheets and of e.g.
• T1/2 for sheets without a topcoat and wherein T1 for example indicates the smallest bending dimension, wherein despite affixing strips of Tesafilm ⁇ 4104 in the area of the bend and subsequently tearing the Tesafilm away no damage visible to the naked eye occurs.
• a copper sulfate solution was applied beforehand. If no visible discoloration of the surface occurs, it can be assumed that the surface is undamaged.
• the surface slip and forming properties were determined using the Erichsen cup indentation test.
• An Erichsen 142-20 cup drawing device with a 33 mm punch diameter and a pressing rate of 750 mm/min was used for testing on blanks of 60 mm diameter made from metal sheets coated according to the invention. This test was used to determine whether the formed sheets are free from abrasion and striation, wherein this is also used as a measure of the impact of rolling and forming processes.
• the elasticity and bond strength were also determined on metal sheets coated according to the invention by means of the Erichsen indentation test in accordance with DIN EN ISO 1520 with ball indentation from a ball of 20 mm diameter and using an Erichsen 202-C device, wherein the ball was pushed into the uncoated back of the metal sheet coated on one side according to the invention at a speed of 0.1 to 0.3 mm/sec. A cross-hatch adhesion grid was not used in this case.
• the formed sheets should display no cracks or peeling of the coating; the indentation depth in mm is measured before the first faults start to develop, such as peeling or cracks which are visible to the naked eye. Sheet thicknesses of 0.75 mm were used for testing.
• the bond strength and freedom from peeling and cracks can be tested again if required on the formed parts by affixing and then tearing off strips of Tesafilm. The greater the indentation values, the better the elasticity and bond strength.
• the elasticity that was measured is in some cases markedly better than in conventional primer coatings.
• the corrosion resistance was measured on metal sheets coated according to the invention in a salt spray test according to DIN 50021, firstly over the area of the metal sheets coated according to the invention and secondly on scratched sheets coated according to the invention, by means of subsurface migration at the scratch after test times of varying lengths.
• the anticorrosive coating according to the invention could be overpainted very effectively, which is by no means self-evident, and displayed a very high chemical resistance, wherein the high quality was also achieved through the choice of resins and their crosslinking.
• the overpainting ability could be improved with the same measures that were used to improve the adhesion.
• the anticorrosive coating according to the invention displayed practically no embrittlement, unlike aqueous UV systems, in which embrittlement can be clearly observed firstly after a period of 2 to 3 days of curing after UV irradiation and secondly over the years thereafter in long-term ageing.
• anionically, cationically or/and radically curing binder systems displaying so little embrittlement have not previously been known in a 100% system (paint-like system with little or no content of water or/and solvent(s)).
• the embrittlement tendency was determined on metal sheets coated according to the invention and cured, by means of the T-bend test as a flexibility test in accordance with ECCA standard T7, before and after an additional ten UV irradiation cycles at a wavelength of around 340 nm and with a luminance of around 600 mJ/cm 2 , 2 days after application.
• the embrittlement tendency is low or undetectable if the T-bend test values are unchanged in comparison to the T-bend test values prior to these additional irradiation cycles after an additional five UV irradiation cycles and exceptionally low or undetectable after the use of an additional eight irradiation cycles.
• the anticorrosive coating according to the invention proved to be tack-free.
• the reactivity of the binder system according to the invention could be dramatically improved, in particular through the choice of photoinitiators—in particular according to their reactivity, more reactive binders and the addition of tertiary amine, wherein binders were preferably chosen which with adequate curing display an MEK resistance of over 40 cycles with a dry film thickness of just 8 ⁇ m; in the tests, however, an MEK resistance of up to 132 cycles was even achieved. Furthermore, with a slower belt speed and alternatively with a higher number of UV lamps, which with the same film thickness also led to slower UV curing, MEK cycle counts of 106, 110, 119, 123 and 132 were achieved. In the MEK test it is important to keep all test conditions constant, especially the wiping conditions.
• the water resistance was tested in the condensation water alternating climate test in accordance with DIN 50017 for 400 h.
• the metal sheets coated according to the invention were stored in deionised water without being moved.
• blister-free anticorrosive coatings showing no signs of damage to the naked eye could be obtained in many cases after 400 h of testing. Some samples could successfully withstand this test for 500 h or even for 600 h.
• examples B 25 to B 29 a different modified polyurethane acrylate with improved reactivity was used in place of the unmodified polyurethane acrylate previously used.
• this content was also slightly increased and the proportion of isobornyl methacrylate reduced accordingly.
• benzophenone was also replaced by a more reactive mixture based on alkyl benzoyl formate.
• this content was also increased slightly.
• polypropylene wax was also added in addition. Otherwise the manufacturing conditions for the coated substrates were very largely identical to those for the previously described examples.
• Soya lecithin oil 0.5 — — — — — — — — — — — 3.e. Tertiary amine — — — — — — — — — — — — Corrosion inhibitors 4.a. (Benzothiazol-2- 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 1 1 1 1 ylthio)succinic acid derivative 4.b. 4-Oxo-4-tolyl butanoic acid — — — — — — — — — — — 4.c. Ca-modified silicate pigment 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 Photoinitiators 5.a.

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• 2003
  • 2003-01-11 DE DE10300751A patent/DE10300751A1/de not_active Withdrawn
• 2004
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  • 2004-01-09 PL PL378248A patent/PL209668B1/pl unknown
  • 2004-01-09 WO PCT/EP2004/000108 patent/WO2004063294A1/de active Application Filing
  • 2004-01-09 ES ES04701002.0T patent/ES2628231T3/es not_active Expired - Lifetime
  • 2004-01-09 US US10/540,721 patent/US20060228481A1/en not_active Abandoned
  • 2004-01-09 EP EP04701002.0A patent/EP1585793B1/de not_active Expired - Lifetime
  • 2004-01-09 AU AU2004203920A patent/AU2004203920C1/en not_active Ceased
  • 2004-01-09 MX MXPA05007213A patent/MXPA05007213A/es active IP Right Grant
  • 2004-01-09 BR BRPI0406487-9A patent/BRPI0406487B1/pt not_active IP Right Cessation
  • 2004-01-09 CN CNB2004800063024A patent/CN100560659C/zh not_active Expired - Fee Related
  • 2004-01-09 CA CA2513003A patent/CA2513003C/en not_active Expired - Fee Related
• 2010
  • 2010-11-03 US US12/938,584 patent/US20110045201A1/en not_active Abandoned
• 2012
  • 2012-01-06 US US13/344,642 patent/US9695322B2/en not_active Expired - Fee Related

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