Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
  • B05D7/50—Multilayers
  • B05D7/56—Three layers or more
  • B05D7/57—Three layers or more the last layer being a clear coat
  • B05D7/577—Three layers or more the last layer being a clear coat some layers being coated "wet-on-wet", the others not

Definitions

• the invention relates to a method for producing a multilayer painting, especially metallic substrates, the is particularly suitable for automotive painting.
• Basecoat and clearcoat are preferably wet-on-wet applied, i.e. the basecoat is after a flash-off time, if necessary with heating, and after subsequent application a clear varnish baked together with this.
• EP-A-0 238 037 is a method to reduce burn-in layers become known in which a filler and an aqueous metallic base coat applied by the wet-on-wet method. The sample part is it can be seen that the filler layer in a usual for filler paints Dry film thickness of 35 microns is applied.
• the object of the invention is to provide a method for producing Multi-layer paintwork, in particular of automotive paintwork with comparable to the prior art Overall property level, but reduced layer thickness of the To provide overall paint structure, which with as few as possible Burn-in steps can be carried out.
• the method of multi-layer coating of the invention provided with a burned-in first electrocoat layer Substrate, which is characterized in that on this first Electrocoating layer a second coating layer corresponding to one Dry layer thickness from 10 to less than 30 ⁇ m from a first aqueous, color and / or effect basecoat, the one or contains several polyurethane resins, is applied, whereupon wet-on-wet a third coating layer corresponding to a dry layer thickness of 7 to 15 microns from a second aqueous, color and / or effect Basecoat coating agent applied and on the third coating layer a fourth coating layer from one without baking Clear lacquer coating agent applied and the second, third and fourth Coating layer are baked together, with a first aqueous Basecoat is used, which has a higher content Polyurethane resin has as the second basecoat based on the total weight of the respective aqueous basecoat coating agent, and the solid resin content in the first basecoat coating agent not more than
• the method according to the invention makes it possible to directly access a burned-in first coating layer created by electrodeposition apply an aqueous basecoat and this layer together with the subsequently applied second Burn in the water-based lacquer layer and clear lacquer layer, using usual Filler layers or other intermediate layers are eliminated.
• the first layer of coating namely a primer
• ETL cathodically depositable electrocoat materials
• aqueous coating agents with a Solids up to 50% by weight, for example 10 to 20% by weight.
• the Solid is formed from the usual for electrodeposition painting Binders, the ionic groups or in ionic groups convertible groups and, if necessary, for chemical crosslinking capable groups, and any existing crosslinkers, Pigments, fillers and / or additives common in paint.
• the Ionic or groups which can be converted into ionic groups can be anionic or groups which can be converted into anionic groups, e.g. acidic groups like - COOH groups or cationic or convertible into cationic groups, e.g. basic groups such as amino, ammonium, e.g.
• Binders with basic groups are preferred. Particularly preferred are nitrogen-containing basic groups. These groups can quaternized or at least partially with one usual neutralizing agent, an acid, e.g. an organic Monocarboxylic acid, e.g. Formic acid or acetic acid, in ionic Groups convicted.
• an acid e.g. an organic Monocarboxylic acid, e.g. Formic acid or acetic acid, in ionic Groups convicted.
• the electrodeposition lacquer layer For the production of the first coating layer, the electrodeposition lacquer layer, it is possible, for example, to use the usual anodically depositable electrodeposition lacquer binders and lacquers (ATL) containing anionic groups.
• ATL lacquers
• binders based on polyesters, epoxy resins, poly (meth) acrylates, maleate oils or polybutadiene oils with a weight average molecular weight of, for example, 300 to 10,000 and an acid number of 35 to 300 mg KOH / g.
• the binders carry, for example, -COOH, -SO 3 H and / or -PO 3 H 2 groups. After neutralization of at least some of the acidic groups, the resins can be converted into the water phase.
• the binders can be self-crosslinking or externally crosslinking.
• the lacquers can therefore also contain customary crosslinking agents, for example triazine resins, crosslinking agents which contain groups capable of transesterification or blocked polyisocyanates.
• customary crosslinking agents for example triazine resins, crosslinking agents which contain groups capable of transesterification or blocked polyisocyanates.
• Specific examples of such anodically depositable electrodeposition paint binders and paints (ATL) which contain anionic groups and can be used in the process according to the invention are described, for example, in DE-A-28 24 418.
• cathodic electrodeposition paints are preferred based on cationic or basic binders for the production of first coating layer used.
• Such basic resins are for example primary, secondary or tertiary amino groups resins containing, the amine numbers e.g. at 20 to 250 mg KOH / g lie.
• the weight average molecular weight (Mw) of the base resins is preferably from 300 to 10,000.
• Examples of such base resins are Amino (meth) acrylate resins, amino epoxy resins, amino epoxy resins with terminal double bonds, amino epoxy resins with primary OH groups, Aminopolyurethane resins, amino group-containing polybutadiene resins or modified epoxy resin-carbon dioxide-amine reaction products.
• This Base resins can be self-crosslinking or they are known Crosslinkers used in the mixture.
• Crosslinkers are Aminoplast resins, blocked polyisocyanates, crosslinkers with terminal Double bonds, polyepoxide compounds or crosslinkers Contain transesterifiable groups.
• Specific examples of in base resins and cathodic dip lacquer (KTL) baths Crosslinkers are e.g.
• EP-A-0 082 291 EP-A-0 234 395, EP-A-0 227 975, EP-A-0 178 531, EP-A-0 333 327, EP-A-0 310 971, EP-A-0 456 270, US 3,922,253, EP-A-0 261 385, EP-A-0 245 786, DE-A-33 24 211, EP-A-0 414 199, EP-A-0 476 514.
• Such resins can be used alone or in a mixture.
• Prefers so-called “non-yellowing" -KTL systems are used, the one Yellowing or discoloration of the multi-layer coating when baked avoid.
• it is by means of special selected blocked polyisocyanate crosslinking KTL systems, such as described for example in EP-A-0 265 363.
• ETL electrocoat
• pigments and fillers come the usual inorganic and / or organic pigments and Fillers in question. Examples are carbon black, titanium dioxide, Iron oxide pigments, phthalocyanine pigments, quinacridone pigments, kaolin, Talc or silicon dioxide.
• the pigments can be dispersed into pigment pastes, e.g. under Use of known paste resins. Such resins are known to the person skilled in the art common. Examples of paste resins that can be used in KTL baths are in EP-A-0 183 025 and EP-A-0 469 497.
• additives are known for ETL coating agents.
• examples include wetting agents, Neutralizing agents, leveling agents, catalysts, Corrosion inhibitors, anti-foaming agents, solvents, in particular however, light protection agents if necessary in combination with Antioxidants.
• the second and the third coating layer the usual, familiar to the skilled worker aqueous color and / or effect basecoat used as for the production of basecoat / clearcoat two-coat paint be used and in large numbers be described for example in the patent literature.
• the waterborne basecoats can be physically drying or under Formation of covalent bonds can be cross-linked. With the under It can form water-based paints that crosslink covalent bonds are self- or third-party networking systems. It can be one or be two-component systems, one-component systems are preferred.
• the waterborne basecoats which can be used in the process according to the invention contain water-dilutable binders. These contain for Ensuring their water dilutability conferring hydrophilicity non-ionic and / or ionic groups.
• Suitable non-ionically stabilized binders are such binders, the water dilutability by incorporation of Polyether segments in the resin molecule is reached.
• Specific Examples of such stabilized polyurethane or Polyurethane acrylate resins are e.g. in EP-A-0 354 261, EP-A-0 422 357 and EP-A-0 424 705.
• binders containing ionic groups can be cationic or anionic groups Trade binders.
• Stabilized binders are wholly or partially neutralized cationic (meth) acrylic copolymer, polyester, Polyurethane and / or polyurethane urea resins, especially with one Number average molecular weight (Mn) from 500 to 500000, an OH number of 0 to 450, an amine number from 20 to 200 and one Glass transition temperature from -50 to + 150 ° C.
• Mn Number average molecular weight
• Specific examples of these binders familiar to the person skilled in the art, are described in DE-A-40 11 633 described.
• the waterborne basecoats preferably contain binders which are about anionic groups are stabilized. It is a or several film-forming resins, such as those in aqueous coating compositions, are common, especially in aqueous basecoats.
• the film-forming Resins can, for example, polyester, (meth) acrylic copolymer or preferably be polyurethane resins. You can self or cross-linking or physically drying. Specific examples for suitable water-dilutable (meth) acrylic copolymers e.g. in EP-A-0 399 427 and EP-A-0 287 144.
• suitable water-dilutable polyester resins are e.g. in DE-A-29 26 854, DE-A-38 32 142 and EP-A-0 301 300.
• binders are those in which (meth) acrylic copolymer and Polycondensation resin covalently or in the form of interpenetrating Resin molecules are connected.
• the combination is (meth) acrylic copolymer and polyester resin.
• Specific Examples of such a usable combination are, for example in EP-A-0 226 171.
• Anionically stabilized polyurethane resins are particularly preferred used. Such polyurethane resins are familiar to the person skilled in the art and are described in great variety in the literature. It is about thereby aqueous polyurethane dispersions or solutions or such Binder in which (meth) acrylic copolymer and polyurethane resin covalent or in the form of interpenetrating resin molecules. Examples of suitable polyurethane dispersions are stable, aqueous Dispersions with a solids content of 20 to 50% by weight.
• the Weight-average molecular weight (Mw) of the resins can vary within wide limits fluctuate, e.g. from 1000 to 500000.
• the polyurethane resins can functional groups such as Hydroxyl groups or blocked Contain isocyanate groups.
• polyurethane dispersions are those that are isocyanate-functional by chain extension
• Prepolymers can be made with polyamine and / or polyol. They are described, for example, in EP-A-0 089 497, EP-A-0 228 003, DE-A-36 28 124 and EP-A-0 512 524.
• polyurethane dispersions that are made by Chain extension of isocyanate-functional prepolymers with water can be produced, e.g. in DE-A-39 15 459 and DE-A-42 24,617.
• anionically stabilized usable Polyurethane (PU) dispersions are those that are available through Chain extension of at least one CH-acidic group in the molecule containing polyurethane resins with compounds with at least two CH-acidic groups can react. These are special examples polyurethane resin dispersions described in DE-A-42 28 510.
• PU dispersions based on siloxane bridges can also be used chain-extended polyurethane resins can be used. Such are e.g. known from DE-A-44 13 562.
• the waterborne basecoats can be a single aqueous binder contain, but also several aqueous binders in Combination.
• Aqueous binders based on are preferred contain anionically stabilized polyurethanes. It can be convenient if a part, e.g. up to 50% by weight of the polyurethane binder by resins based on a combination of (meth) acrylic copolymer and Polyester resin is replaced.
• water-dilutable binders based on cellulose be included.
• the crosslinking agents familiar to those skilled in the art, such as, for example, formaldehyde condensation resins, such as phenol-formaldehyde condensation resins and amine-formaldehyde condensation resins, as well as free or blocked Polyisocyanates are used.
• the crosslinkers can be used individually or in Mixture can be used.
• the mixing ratio crosslinker too Binder resin is preferably 10:90 to 40:60, especially preferably 20:80 to 30:70, in each case based on the Solid weight.
• the waterborne basecoats used in the process according to the invention contain in addition to the usual physically drying and / or chemical crosslinking binders pigments.
• the expression used here "Pigments" includes inorganic and / or organic colored pigments and / or effect pigments and any fillers present. All common pigments can be used; examples are Titanium dioxide, iron oxide pigments, carbon black, azo pigments, Phthalocyanine pigments, metal pigments, e.g. made of titanium, aluminum or Copper, interference pigments, e.g. titanium dioxide coated Aluminum, coated mica, graphite effect pigments, platelet-shaped iron oxide, platelet-shaped Copper phthalocyanine pigments, talc, barium sulfate, kaolin, Silicon dioxide.
• first and second basecoat coating compositions differ in their pigment / volume concentration (PVC) by no more than 30% of the absolute value of the pigment / volume concentration in the second basecoat coating composition.
• the pigment / volume concentration of the first basecoat coating composition is preferably below that of the second basecoat coating composition.
• the same is preferred in both basecoat coatings Pigments, particularly preferably the same pigmentations used.
• the pigmentation is the relative composition of a To understand pigment mixture, d. H. the type of pigments and their respective proportions in the pigment mixture. It is also preferred in the two basecoat coatings pigmentations with similar average specific weight (this results from the relative proportions of the individual pigments) to use.
• the average specifics preferably differ Weights of the pigmentations in the two basecoat coatings not more than 20% based on the average specific Weight of pigmentation in the second waterborne basecoat.
• the color-imparting absorption pigments (colored pigments) and, if necessary Fillers are generally found in some of the water-dilutable Binder ground.
• the rubbing can preferably also be carried out in one special water-thinnable paste resin happen. They can do that Paste resins known to those skilled in the art and suitable for aqueous systems be used. A specific example of a preferred usable paste resin based on an anionically stabilized Polyurethane resin can be found in DE-A-40 00 889. The rubbing takes place in conventional units known to the person skilled in the art. After that with the remaining portion of the aqueous binder or the aqueous Paste resin for the finished pigment pigment grinding completed. Are in paste resins are present in the waterborne basecoat, these add up Binders plus any crosslinker present. Either Binders as well as crosslinkers and paste resins together make up the Solid resin content of the water-based paints.
• waterborne basecoats can be used as auxiliaries included, such as Catalysts, leveling agents, anti-foaming agents, Anti-cratering agents or, in particular, light stabilizers, if appropriate Connection with antioxidants.
• the water-based paints for example, have a solids content of 10 to 50% by weight, for example, for effect basecoats preferably 15 - 30 wt .-%, for plain-colored basecoats it is preferably higher, for example at 20-45% by weight.
• the ratio of Pigment to binder plus crosslinker plus if necessary optionally paste resin in the water-based lacquer is, for example between 0.03: 1 to 3: 1, for effect basecoats it is for example preferably at 0.06: 1 to 0.6: 1, for plain-colored Basecoats are preferably higher, for example 0.06: 1 to 2.5: 1, each based on the solid weight.
• the one for generation the second water-based paint used in the second coating layer preferably a lower pigment / binder ratio than that for Generation of the third coating layer used second Wet basecoat.
• binding agent includes the or the Binder as such plus any crosslinker present any paste resins present, the sum of these Constituents represent the solid resin content of the water-based paints.
• the first to generate the second Coating layer used waterborne basecoat compared to the second waterborne basecoat used to create the third coating layer characterized by a higher proportion by weight of polyurethane resins.
• the absolute value preferably corresponds to this excess Polyurethane resins in the first water-based paint between 5 and 50%, particularly preferably between 10 and 35% of the absolute value of the Solid resin weight content in the second coating agent.
• the second basecoat coating agent has a solid resin content from 20% by weight
• the preferred absolute value for is calculated the polyurethane content in the first basecoat coating composition as a sum the polyurethane content X (% by weight) of the second coating agent plus 5 to 50% of 20% by weight, i.e.
• the polyurethane content of the first Coating agent is then preferred: X + (1 to 10) wt .-%.
• the absolute value of the weight content differs Solid resin in the first basecoat by no more than 20% of the absolute value of the weight content of solid resin in the second Basecoat coating compositions; in the example above is Solid resin content of the second basecoat coating composition 20 wt .-%, so accordingly the solid resin content of the first basecoat coating composition total 16 to 24 wt .-%.
• the solid resin content of the first coating agent particularly preferably equal to or higher than that of the second basecoat coating agent.
• the first Basecoat coating composition according to a preferred procedure from the second basecoat coating agent by admixing a corresponding one Amount of polyurethane resin can be produced.
• polyurethane resins that the higher proportion in can make out first waterborne basecoat are the above as Binder suitable for water-based paints Polyurethane resins.
• the second waterborne basecoat in the first waterborne basecoat of a higher proportion of polyurethane resin can be used for the process according to the invention
• manufactured second and third coating layers are also in others
• Water-based paints that differ from one another, preferred however, similar waterborne basecoats can be used.
• the two water-based paints preferably differ only by the above-mentioned essential to the invention Distinguishing feature. This is explained in more detail below.
• a clear coat for the generation of the fourth and any additional coating layers are in principle all usual clear coats or transparent colored or colorless pigmented Coating agent suitable. It can be one or act multi-component clear lacquer coating agents. You can be solvent-free (liquid or as a powder clear coat), or it can are systems based on solvents or are are water-thinnable clear coats, whose binder systems in suitably, e.g. anionic, cationic or non-ionic, are stabilized. With the water-borne clear lacquer systems it can are water-soluble or water-dispersed systems, act, for example, emulsion systems or powder slurry systems. The Clear lacquer coating agents harden during baking under training covalent bonds due to chemical cross-linking.
• the clear lacquers which can be used in the process according to the invention are concerned it is the usual clearcoat coating agent, the expert are common and the one or more common base resins as contain film-forming binders. You can, if the base resins are not self-crosslinking and may also contain crosslinking agents. Both the base resin component and the crosslinker component are not subject to any restrictions.
• a film-forming binder can, for example, polyester, polyurethane and / or (Meth) acrylic copolymer resins can be used.
• Water-clear lacquer systems used as clear lacquer in the process according to the invention can be used can be found in DE-A-39 10 829, DE-A-40 09 931, DE-A-40 09 932, DE-A-41 01 696, DE-A-41 32 430, DE-A-41 34 290, DE-A-42 03 510, EP-A-0 365 098, EP-A-0 365 775, EP-A-0 496 079, EP-A-0 546 640.
• powder clearcoat systems in the invention Processes that can be used as clear lacquer can be found in EP-A-0 509 392, EP-A-0 509 393, EP-A-0 522 648, EP-A-0 544 206, EP-A-0 555 705, DE-A-42 22 194, DE-A-42 27 580.
• the transparent coating can be in a single layer or in shape of multiple layers from the same or from several different transparent coating agents can be applied.
• a substrate for the method according to the invention are electrical conductive materials, such as metals. Particularly suitable are e.g. Automobile bodies or parts of them, them can be made of pretreated or untreated metal, with a electrically conductive layer provided metal or electrically conductive or provided with an electrically conductive layer Plastic.
• the first one is on these substrates Coating layer, especially in the form of a Corrosion protection primer, electrophoretically in the usual way and in a usual dry layer thickness of ETL primers for example, 15 to 35 microns deposited and baked.
• a Corrosion protection primer electrophoretically in the usual way and in a usual dry layer thickness of ETL primers for example, 15 to 35 microns deposited and baked.
• multi-layer coatings are obtained more than the four coating layers produced according to the invention, nevertheless is in the context of the present invention in the invention Process first applied electrocoat layer first Called coating layer.
• Waterborne basecoat preferably in one spray pass in one of the Opacity of the color-dependent dry layer thickness from 10 to less than 30 ⁇ m, for example 10 to 29 ⁇ m, preferably 10 to 25 ⁇ m, applied particularly preferably from 10 to 20 microns.
• Suitable spray application methods are compressed air spraying, airless spraying or electrostatic (ESTA) high-rotation spraying, wherein electrostatic spraying for the application of the first waterborne basecoat is the preferred application method.
• the third Coating layer from the second color and / or effect Waterborne basecoat in one spray pass preferably by compressed air spraying preferably in a smaller dry layer thickness than the second Coating layer, applied from only 7 to 15 ⁇ m and briefly vented, optionally at temperatures up to 80 ° C, for example during 1 to 5 minutes, e.g. by exposure to infrared radiation.
• the third coating layer is applied and vented the application of the clear lacquer in the wet-on-wet process.
• the fourth coating layer is made from a common liquid clear coat or powder clearcoat (in this case it is a dry-on-wet application) in a usual for clear lacquer layers Dry layer thickness of for example 30 to 80 microns, preferably 30 to 60 ⁇ m, overpainted and together with the second and third Coated layer.
• the Baking temperature when baking the three together Coating layers between 80 and 160 ° C, preferably below 140 ° C. If necessary, further layers of clear lacquer from the same or of which various clear lacquer coating agents before or after Branding can be applied.
• the method according to the invention allows the production of four or even multi-layer paintwork, in particular automotive paintwork with compared to the prior art, the filler layers and / or includes other intermediate layers, reduced total layer thickness and comparable overall property level. There are only two Burn-in steps necessary. It has been shown to be excellent Properties achieved by the procedure according to the invention even though this eliminates the need for conventional filler layers.
• this waterborne basecoat is 13.8% by weight.
• Pre-coated body panels are sprayed on Waterborne basecoat (blue metallic) from Example 1 in one Dry layer thickness of 15 ⁇ m applied. After the application flashed off briefly and then a second layer of the same Waterborne basecoat in a dry layer thickness of 10 ⁇ m also through Syringes applied. It is predried at 80 ° C. for 10 minutes. Subsequently, the 2K-HS car series clear coat from Example 1 is used overcoated with a dry film thickness of 40 ⁇ m and at 30 minutes 130 ° C (object temperature) dried.
• Body panel On a usual phosphated and by cathodic dip painting and pre-coated with a 30 ⁇ m thick filler layer Body panel is made by spraying the one described below Waterborne basecoat (black) in a dry layer thickness of 20 ⁇ m upset. After application, the product is briefly vented and then Predried at 80 ° C for 10 minutes.
• Waterborne basecoat black
• This waterborne basecoat has a solid resin content of 21.9% by weight.
• Pre-coated body panels are sprayed on Water-based paint (black) from example 4 in a dry layer thickness of 15 ⁇ m applied. After application, the product is briefly vented and then a second coat of the same waterborne basecoat in a dry film thickness of 10 ⁇ m also by spraying upset. It is predried at 80 ° C. for 10 minutes. Subsequently is with the 2K-HS car series clear coat from Example 1 in one Dry layer thickness of 40 ⁇ m overcoated and 30 minutes at 130 ° C (Object temperature) dried.
• the water-based paints 6a), 6b) and 6c) each have one Solid resin content of 23.7% by weight.
• Table 1 summarizes the results of the stone chip tests carried out. Multi-layer painting 1 2nd 3a 3b 3c 4th 5 6a 6b 6c VDA rockfall 1 3rd 1 1 1 3rd 1 1 Stone chipping using the "split method" 7 12th 3rd 5 6 5 10th 4th 4th 4th 0-1 4-5 0-1 0-1 1 0-1 4-5 0-1 0-1 1 1 0-1 4-5 0-1 0-1 1 1

Landscapes

• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Wood Science & Technology (AREA)
• Application Of Or Painting With Fluid Materials (AREA)
• Paints Or Removers (AREA)

Applications Claiming Priority (3)

Publications (2)

Family

ID=7786172

Family Applications (1)

Country Status (8)

Cited By (1)

Families Citing this family (47)

Family Cites Families (8)

• 1996
  • 1996-02-23 DE DE19606716A patent/DE19606716C1/de not_active Expired - Lifetime
• 1997
  • 1997-02-19 DE DE59700330T patent/DE59700330D1/de not_active Expired - Lifetime
  • 1997-02-19 US US09/101,271 patent/US5976343A/en not_active Expired - Fee Related
  • 1997-02-19 BR BR9707608A patent/BR9707608A/pt not_active IP Right Cessation
  • 1997-02-19 JP JP52978997A patent/JP4096069B2/ja not_active Expired - Fee Related
  • 1997-02-19 EP EP97903326A patent/EP0881954B1/de not_active Expired - Lifetime
  • 1997-02-19 AU AU17924/97A patent/AU1792497A/en not_active Abandoned
  • 1997-02-19 ES ES97903326T patent/ES2140962T3/es not_active Expired - Lifetime
  • 1997-02-19 WO PCT/EP1997/000784 patent/WO1997030795A1/de active IP Right Grant

Also Published As

Similar Documents

Legal Events