Surface conditioner for metallic surfaces prior to conversion coating

Abstract

The present invention relates to an aqueous surface conditioning concentrate for metallic surfaces comprising (a) one or more laminar clay minerals; (b) one or more zinc phosphates; and (c) one or more acrylic polymers, in an aqueous carrier medium, wherein the (c) (meth)acrylic polymers comprise a poly(meth)acrylic backbone and side chains comprising hydroxyl terminated poly(alkylene oxide) chains. The invention also relates to an aqueous surface conditioner, obtainable by diluting the afore-mentioned concentrate and its use as a surface activating composition of a metal material prior to a chemical conversion treatment step. The invention further comprises a method of surface activating a metal material prior to a chemical conversion treatment, and a method of surface pre-treating a metal material, the method comprising surface activating a metal material with the aqueous surface conditioner and contacting the thus obtained activated surface with a chemical conversion treatment composition.

Description

[0001] Chemetall GmbH Dec. 05, 2025

[0002] SURFACE CONDITIONER FOR METALLIC SURFACES PRIOR TO

[0003] CONVERSION COATING

[0004] The present invention relates to an aqueous surface conditioner concentrate for metallic surfaces and an aqueous dilution thereof and its use, a method of surface activating a metal material prior to a chemical conversion treatment, making use of the dilution of the aqueous surface conditioner concentrate, and a method of surface pre-treating a metal material, comprising the application of the afore-mentioned surface activation since, followed by contacting the thus obtained activated surface with a chemical conversion treatment composition.

[0005] BACKGROUND

[0006] Automobile bodies, household electrical appliances or the like are commercialized by forming metal moldings from metal materials such as steel sheets, galvanized steel sheet, sheets of an aluminum alloy, sheets of zinc or magnesium or their alloys, such as zinc-magnesium alloy or the like, subsequently coating and assembling. Coating of such metal moldings are conducted after performing various steps such as cleaning, surface activation, chemical conversion treating, electrodeposition coating and finally applying primer coating materials and topcoat materials, such as basecoat materials and clearcoat materials.

[0007] Surface activation is a treatment step performed before the application of a chemical conversion treatment step.

[0008] For example, EP-A-1 378 586 discloses a zinc phosphate containing surface conditioning agent to be used for surface activation prior to zinc phosphate conversion coating of a metallic material, which contains from 500 to 20,000 ppm of zinc phosphate and which has a pH from 3 to 11 , wherein said zinc phosphate has an average particle size of at most 3 pm and D90 of at most 4 pm.

[0009] WO-A-2019 / 238573 concerns an aqueous dispersion comprising (a) at least 5 % by weight of a dispersed particulate component comprising (a1) at least one particulate inorganic compound of a polyvalent metal cation possessing a D50 value of more than 10 pm, and (a2) at least one polymeric organic compound which is composed at least in part of styrene and / or an a-olefin having no more than 5 carbon atoms and maleic acid, its anhydride and / or its imide and which additionally has polyoxyalkylene units, and (b) at least one thickener.

[0010] EP-B-1 566 466 relates to a surface conditioner, containing zinc phosphate particles and having a pH of 3 to 12, wherein said zinc phosphate particles have a D50 value of 3 pm or less and said surface conditioner contains carboxylate group-containing copolymers obtained by copolymerizing a monomer composition containing acrylic acid in an amount less than 50 % by weight and 2-acrylamido-2-methyl propane sulfonic acid and / or allyl sulfonic acid in a total amount more than 50 % by weight, and a hectorite. Chemetall GmbH Dec. 05, 2025

[0011] WO 00 / 05066 A describes a liquid composition for conditioning metal surfaces prior to phosphate conversion coating treatment thereof wherein said liquid composition contains solid microsize particles of at least one phosphate of a divalent or trivalent metal and an accelerant selected from saccharides and their derivatives, orthophosphoric acids, organophosphonic acids, and polymers of vinyl acetate and / or carboxylic acid.

[0012] WO 01 / 12341 A relates to a process of forming a phosphate conversion coating on a metal substrate surface, wherein a metal surface is surface conditioned by contact with a liquid surface conditioner composition that contains dispersed fine particles of solid phosphate of at least one divalent or trivalent cations type and an adhesion promoting agent.

[0013] EP-A-0 117 599 relates to a process for pretreating metal surfaces prior to phosphate conversion coating treatment and an aqueous composition used in this process. The aqueous composition contain montmorillonite in an amount of preferably 0.01 to 10 g / l.

[0014] In US 2017 / 0306498 A1 an activation rinse for treating at least a portion of a substrate is disclosed, which comprises a dispersion of metal phosphate particles having a D90 particle size of no greater than 10 pm, wherein the metal phosphate comprises divalent or trivalent metals or combinations thereof and which further comprises a dispersant; and a metal sulfate salt.

[0015] The aims of the present invention are to provide a surface conditioner concentrate, which is not only long-term stable under storage conditions, but also provides - in diluted form - a conditioner providing, if used prior to a chemical pretreatment, an excellent paint adhesion, particularly regarding corrosive undermining on different metallic substrates including steel, galvanized substrates, such as hot-dip galvanized steel or electrogalvanized steep, and aluminum and its alloys. Further, the thus treated metal materials should also possess an excellent stone-chip resistance.

[0016] SUMMARY

[0017] The above aims were achieved by providing an aqueous surface conditioner concentrate for metallic surfaces comprising

[0018] (a) one or more laminar clay minerals;

[0019] (b) one or more zinc phosphates; and

[0020] (c) one or more (meth)acrylic polymers, in an aqueous carrier medium, wherein the (c) (meth)acrylic polymers comprise a poly (meth)acry I ic backbone and side chains comprising hydroxyl terminated poly (alkylene oxide) chains. Chemetall GmbH Dec. 05, 2025

[0021] The surface conditioner concentrate above and its preferred embodiments as described herein-below are denoted as "surface conditioner concentrate according to the invention.”

[0022] The term "comprising” as used in the present invention always includes the limiting meaning "consisting of” and the open non-exclusive meaning "containing.”

[0023] The terms "conditioning” or "conditioner” as used herein and in the field of the invention, is interchangeable with and used in accordance with the meaning of the term "activation” as defined in ISO 2080:15-07-2008 "Metallic and other inorganic coatings - Surface treatment, metallic and other inorganic coatings - Vocabulary” (herein after referred to as ISO 2080, only). According to ISO 2080 "activation” is the elimination of a passive surface condition. Thus, the surface conditioner concentrate can also be denoted as a "surface activation concentrate.”

[0024] The term "aqueous carrier medium” as used herein above and below defines a carrier medium essentially consisting of water, preferably the aqueous carrier medium comprises at least 95 wt.-%, more preferred at least 98 wt.-%, even more preferred at least 99 wt.-%, such as at least 99.5 wt.-% of water. The term "water” as herein used includes deionized water and mains water, if not specified otherwise.

[0025] Another subject matter of the invention is an aqueous surface conditioner, comprising 0.1 g to 8 g of the aqueous surface conditioner concentrate according to the invention per 1 liter of an aqueous carrier medium.

[0026] The surface conditioner above and its preferred embodiments as described herein-below are denoted as "surface conditioner according to the invention.”

[0027] A further subject matter of the invention is a method of surface activating a metal material prior to a chemical conversion treatment, the method comprising the step of

[0028] (I) contacting at least part of the surface of the metal material with the surface conditioner according to the invention.

[0029] The afore-mentioned method of surface treating a metal material prior to a chemical conversion treatment and its preferred embodiments as described herein-below are denoted as "surface activating method according to the invention.”

[0030] Yet another subject matter of the invention is a method of surface pre-treating a metal material, the method comprising the steps of Chemetall GmbH Dec. 05, 2025

[0031] (i) contacting at least part of the surface of the metal material with the surface conditoner according to the invention to obtain an activated surface of the metal material; and subsequently

[0032] (II) contacting the thus obtained activated surface with a chemical conversion treatment composition.

[0033] The afore-mentioned method of surface pre-treating a metal material and its preferred embodiments as described herein-below are denoted as "surface pre-treatment method according to the invention.”

[0034] A further subject matter of the invention is the use of the aqueous surface conditioner as a surface activating composition of a metal material prior to a chemical conversion treatment step.

[0035] The afore-mentioned use and its preferred embodiments as described herein-below are denoted as "use according to the invention.”

[0036] DETAILED DESCRIPTION

[0037] Ingredients of the Aqueous Surface Conditioner Concentrate

[0038] In the following, the ingredients used to produce the aqueous surface conditioner concentrate will be described in more detail.

[0039] (a) Laminar Clay Mineral

[0040] The surface conditioner concentrate of the invention comprises at least one laminar clay mineral. In this case, the surface conditioner concentrate prevents not only the precipitation of zinc phosphate particles in the aqueous surface conditioner concentrate but also the precipitation of zinc phosphate particles in the surface conditioner concentrate (that is, the concentrate of the surface conditioner of the invention before diluting it to the ready-to-use surface conditioner with an aqueous carrier medium, preferably with water), and therefore it can retain a long-term stability of the concentrate.

[0041] By adding the laminar clay mineral, an excellent thickening effect can be exerted and repulsion of charged particles can also be exerted by this addition. Accordingly, although the reason why the precipitation of the concentrated surface conditioner solution can be prevented is not fully clear, it is estimated that an excellent anti-settling behavior of the zinc phosphate is obtained by this thickening effect in synergy with the repulsion of charged particles.

[0042] The above-mentioned laminar clay minerals have electric repulsion per se. Thus, when the above laminar clay minerals adhere to circumferences of zinc phosphate particles, zinc phosphate particles in the surface conditioner concentrate can be stabilized by electric repulsion. Therefore, in preparation of the surface conditioner concentrate Chemetall GmbH Dec. 05, 2025

[0043] (liquid concentrate), it is possible to attain finer zinc phosphate particles in dispersing the ingredients in the solution and also to further improve dispersion efficiency.

[0044] The above laminar clay mineral is not particularly limited, but preferably selected from smectite group minerals such as, e.g., montmorillonite, beiderite, saponite, and hectorite. These laminar clay minerals may be natural minerals or may be synthetic minerals, preferably formed by hydrothermal synthesis, fusion methods, or solid phase methods.

[0045] The laminar clay minerals as used in the preparation of the surface conditioner concentrate preferably have an average diameter below 100 m, more preferably at least 80 %, more preferably at least 85 wt.-%, even more preferred at least 90 wt.-% should pass a US mesh 200 sieve, before any milling or grinding of the concentrate is carried out.

[0046] The above laminar clay minerals are preferably natural hectorite and / or synthetic hectorite. These hectorites can provide the more excellent stability of dispersion for the aqueous surface conditioner concentrate and can further improve the dispersion efficiency.

[0047] The afore-mentioned natural hectorite is typically a trioctahedral type clay mineral included in a montmorillonite group.

[0048] Examples of commercially available products of the above natural hectorite, are, for example, available under the trademark BENTONE® (produced by ELEMENTIS PLC).

[0049] The above-mentioned synthetic hectorites are typically substances which are analogous to hectorite belonging to a trioctahedral mineral of an infinite layer expansion type having a crystal trilaminar structure and an expansive lattice.

[0050] The synthetic hectorites typically comprises magnesium, silicon, sodium, as the main ingredients, and a trace of lithium and fluorine.

[0051] The above synthetic hectorite has a trilaminar structure and each layer of a crystal structure in the laminar structure consists of two-dimensional platelets of about 1 nm in thickness. A lithium atom having a low valence isomorphically substitutes for a part of magnesium atoms existing in a middle layer of this platelet unit and therefore the platelet unit is negatively charged. In a dry condition, this negative charge balances with a displaceable cation present at the outside of a lattice structure in a plate plane and these particles are combined with one another by a Van der Waals force in a solid phase to form a bundle of plates. Chemetall GmbH Dec. 05, 2025

[0052] When such synthetic hectorites are dispersed in a water phase, a displaceable cation is hydrated and particles cause swelling, and a stable sol can be attained by dispersing the resulting particles using a typical dispersing machine such as a high-speed dissolver. In such a state of being dispersed in a water phase, the platelets bear negative charges on their surfaces, repel one another by virtue of their electrostatic repulsion and become a stable sol which has been fractionized up to a primary particle of a platelet form. But, when the concentration of particles or the concentration of ions is increased, repulsion by virtue of negative charge on the surface is decreased and this allows an end portion of the platelet positively charged to be electrically oriented to a plate of another platelet negatively charged and forms the so-called card house structure, resulting in an increase in viscosity.

[0053] It is estimated that when the above synthetic hectorites are used, an excellent thickening property can be thus exerted and therefore it is possible to even better prevent zinc phosphate particles from precipitating in aqueous surface conditioner concentrate and as a result of this, it is possible to retain the long-term stability of dispersion of the concentrate.

[0054] Examples of commercially available synthetic hectorites, are, for example, EP, B, S, RDS, XLG, and XLS types of LAPONITE (trade name) series. These are white powders, which readily form sols (S, RDS and XLS types of LAPONITE series) or gels (B and XLG types of LAPONITE series) when dissolved in water. Particularly preferred are organically modified LAPONITES such as LAPONITE EP.

[0055] The laminar clay materials as used in the present invention include laminar clay minerals comprising intercalated compounds (pillared crystal, etc.), laminar clay minerals subjected to ion-exchanging, laminar clay minerals obtained by applying a surface treatment to the above laminar clay minerals (i.e., surface-treated laminar clay minerals), and partially or fully delaminated laminar clay minerals. These laminar clay minerals may be used alone or in combination of two or more species.

[0056] Natural hectorites and synthetic hectorites may be used alone or in combination of two or more species.

[0057] In the aqueous surface conditioner concentrate of the invention, a content of the above laminar clay minerals is preferably within a range of 0.2 wt.-% (lower limit) to 5.0 wt.-% (upper limit), based on the total weight of the aqueous surface conditioner concentrate. When the content is less than 0.2 wt.-%, a sufficient effect of anti-settling of the zinc phosphate particles in the aqueous surface conditioner concentrate may not be attained. When it is more than 5.0 wt.-%, adsorption of the clay minerals to a metal surface may occur and this adsorption may influence a subsequent chemical conversion treatment step. More preferably, the above lower limit is 0.3 wt.-% and the above upper limit is 4.0 wt.-%, based on the total weight of the aqueous surface conditioner concentrate. Chemetall GmbH Dec. 05, 2025

[0058] (b) Zinc Phosphate

[0059] The aqueous surface conditioner concentrate of the present invention contains zinc phosphate. Here, zinc phosphate is preferably zinc orthophosphate represented by Zn3(PO4)2, which is preferably employed as a hydrate. Surface-treated and / or modified zinc phosphates, inorganically or organically modified, as, e.g., described below are also to be subsumed under the term "zinc phosphate” as commonly used in this field of art.

[0060] In one route to obtain zinc phosphate, as known from prior art, zinc sulfate and a dilute solution of disodium hydrogen phosphate may be mixed and heated in a molar ratio of 3:2, whereby a tetrahydrate of zinc phosphate will be formed as a crystallizable precipitate. If the zinc phosphate used in the present invention is prepared by use of zinc sulfate, it is highly preferred that the resultant zinc phosphate does not contain any residual metal sulfates. However, it is preferred that zinc phosphates as employed in the present invention are obtained, without using sulfates in the production thereof.

[0061] In another prior art route to obtain zinc phosphate, a tetrahydrate of zinc phosphate may be obtained by reacting a dilute phosphoric acid aqueous solution with zinc oxide or zinc carbonate. Crystals of the tetrahydrate are typically of rhombic system, and there are three types of transformation. When heated, it becomes a dihydrate at 100 °C, a monohydrate at 190 °C and an anhydrate at 250 °C. Zinc phosphate in the present invention may preferably be either a tetrahydrate, a dihydrate, a monohydrate or an anhydride, or a mixture of one or more of the aforementioned, but usually a tetrahydrate which is readily available, may be used as it is.

[0062] It is also known from prior art to obtain finely particulate zinc phosphate by adding silica and polyphosphoric acid at the time of reacting a zinc compound with phosphoric acid (e.g., JP-B-49-2005), or to replace a part of zinc in zinc phosphate by a metal such as magnesium, calcium or aluminum by kneading zinc phosphate with various types of a metal compound in a wet system by a mechanical means to complete the reaction mechanochemically (e.g., JP-A-4-310,511 ). For example, it may be one having a component other than phosphorus, oxygen and zinc, such as silica, calcium or aluminum, introduced by such a means, or one commercially available as a silicate- modified zinc-phosphate. In such a case, it preferably contains zinc phosphate corresponding to at least 25 wt.-% as calculated as ZnO and at least 15 wt.-% as calculated as P2O5.

[0063] Suitable and preferred routes to obtain zinc phosphate make use of a reaction between zinc acetate and phosphoric acids, or make use of a reaction between basic zinc carbonate and phosphoric acid (EP 2 007 920 A1).

[0064] Furthermore, as zinc phosphate, one subjected to a surface treatment may be employed. For example, it may be one surface-treated with, e.g., a silane coupling agent, rosin, a silicone compound, or a metal alkoxide such as silicon alkoxide or aluminum alkoxide. Chemetall GmbH Dec. 05, 2025

[0065] The form of zinc phosphate is also not particularly limited. Its commercial product is usually in a white powder form. However, the form of the powder may be any form such as a fine particulate form, a platelet form, or a scaly form. The particle size is also not particularly limited, but it is usually a powder having an z-average particle size in the range from 0.5 m to 8 pm, more preferred in the range from 1 to 5 pm as determined by ISO 22412:2017.

[0066] In the aqueous surface conditioner concentrate of the invention, a content of the above zinc phosphate, calculated as zinc phosphate without crystal water, is preferably within a range of 10 wt.-% (lower limit) to 40 wt.-% (upper limit), based on the total weight of the aqueous surface conditioner concentrate. When the content is less than 10 wt.-%, stability of the dispersion might tend to decrease. When it is more than 40 wt.-%, milling might become more difficult. More preferably, the above lower limit is 15 wt.-% or 20 wt.-% and the above upper limit is 35 wt.-%.

[0067] As described hereinafter, in the present invention, it is possible to prepare a stable dispersion having zinc phosphate finely dispersed.

[0068] (c) (Meth)acrylic Polymer

[0069] The aqueous surface conditioner concentrate of the invention further contains a (meth)acrylic polymer. The term "(meth)acrylic polymer” denotes for polymers which contain, acrylic monomers, methacrylic monomers or both. However, (meth)acrylic polymers may contain further ethylenically unsaturated monomers, such as vinyl ethers and vinyl esters.

[0070] In the present invention, the (meth)acrylic polymer serves as a dispersant for the zinc phosphate particles.

[0071] The (meth)acrylic polymer of the present invention comprises a poly(meth)acrylic backbone and side chains comprising hydroxyl terminated poly(alkylene oxide) chains. The poly(alkylene oxide) chains are preferably depicted by -[AO]nH, wherein A stands for an alkylene residue, preferably alkylene residue selected from ethylene residues (CH2CH2; EO) and propylene residues (CHR'CHR”; PO), with one of R' or R” being H and one of R' or R” being CH3, and n being the number of AO units, preferably n being in the range from 3 to 15 more preferred from 3 to 12, even more preferred from 3 to 10 and most preferred 3 to 8.

[0072] If AO stands for EO and PO, the EO and PO residues may be arranged in any order in the polyoxy alkylene chains, such as arbitrarily, as a gradient, or in two or more blocks, each block consisting of EO or PO residues, only.

[0073] Even more preferred on average at least 50 mole-% of the n AO units are ethylene oxide units (EO), more preferred at least 60 mole-% of the n AO units are EO units, even more preferred at least 70 mole-% are EO units, and most preferred at least 80 mole-% of the AO units are EO units. Most preferred 100 mole-% of the AO units are EO units. Chemetall GmbH Dec. 05, 2025

[0074] The poly (meth)acry lie backbone comprises or even more preferred consists of a chain, formed by polymerization, preferably radical polymerization of monoethylenically unsaturated monomers.

[0075] The finally used (c) (meth)acrylic polymer comprises or consists of monomeric units which are formally derived from polymerizing monoethylenically unsaturated monomers selected from the group of monomers having the following formula (I):

[0076] H2C=CRb-(CO)p-O-(LO)qRa(I), and wherein

[0077] Rais selected from H and a residue of formula [AO]nH, wherein A stands for an alkylene residue, preferably an alkylene residue selected from ethylene residues and propylene residues, n being the number of AO units, preferably being in the range from 3 to 15 more preferred from 3 to 12, even more preferred from 3 to 10 and most preferred 3 to 8, and

[0078] Rbis H or CH3; p = 0 or 1 ; q = 0 or 1 ;

[0079] LO is an ethylene oxide, propylene oxide or butylene oxide; with the provisos that at least part of residues Raare residues of formula [AO]nH.

[0080] Preferably, the (c) (meth)acrylic polymers are formally derived from the monoethylenically unsaturated monomers as depicted above (formula (I)) and below. The term "formally derived” as used herein means that the monomers may either directly be used in the polymerization reaction to produce the (c) (meth)acrylic polymers or be created by attaching the poly (alkylene oxide) side chains to hydroxy groups in a polymer analogues reaction, subsequent to the formation of the polymeric backbone, e.g., by graft reaction.

[0081] For example, this particularly applies to those monomers of formula (I), which comprise a residue of formula [AO]nH. Such residues can, e.g., be introduced into a precursor of the (c) (meth)acrylic polymer, which, for example, comprises monomers of formula

[0082] H2C=CRb-(CO)p-O-(LO)-H by an alkoxylation reaction with ethylene oxide and / or propylene oxide.

[0083] In case of q = 0 and Ra= H, at least part, preferably all of the thus resulting COOH groups are neutralized in the resulting (c) (meth)acrylic polymer. Chemetall GmbH Dec. 05, 2025

[0084] In case p = 1 , the monoethylenically unsaturated monomers of formula (I) are acrylic (Rb= H) or methacrylic (Rb= CH3) monomers.

[0085] In case p = 0, the monoethylenically unsaturated monomers of formula (I) are vinyl (Rb= H) monomers.

[0086] Besides the monoethylenically unsaturated monomers of formula (I) the (c) (meth)acrylic polymer employed in the aqueous surface conditioner of the present invention may further comprise, in polymerized form, maleic anhydride, itaconic anhydride, maleic acid, itaconic acid, and / or salts of the afore-mentioned acids. Amongst the aforementioned, maleic anhydride, maleic acid, and / or salts of maleic acids are even more preferred.

[0087] Preferably, the (c) (meth)acrylic polymer is formed by polymerization of one or more monoethylenically unsaturated monomers selected from the group consisting of monoethylenically unsaturated monomers of formula (I) and optionally maleic anhydride and / or (meth)acrylic acid followed by an at least partial neutralization of COOH groups, if present.

[0088] While further ethylenically unsaturated monomers, particularly monoethylenically unsaturated monomers may be employed in polymerization of the (c) (meth)acrylic polymer, it is preferred that at least 80 mole-%, more preferred at least 90 mole-% and most preferred at least 95 mole-% such as 100 mole-% of the ethylenically unsaturated monomers employed in the polymerization of the (c) (meth)acrylic polymer consist of carbon, oxygen and hydrogen atoms.

[0089] It is even more preferred that at least 80 mole-%, more preferred at least 90 mole-% and most preferred at least 95 mole-% such as 100 mole-% of the ethylenically unsaturated monomers employed in the polymerization of the (c) (meth)acrylic polymer (meth)acrylic monomers comprising poly(alkylene oxide) chains, i.e. monomers of formula (I), wherein p = 1 , q = 1 ,

[0090] LO = an ethylene oxide, propylene oxide or butylene oxide, Rb= H or CH3, preferably CH3 and preferably at least 50 mole-%, more preferred at least 60 mole-%, or further preferred at least 70 mole-%, or even more preferred at least 90 mole-%, such as at least 95 mole-% of the AO units are ethylene oxide units, particularly preferred all AO units are ethylene oxide units.

[0091] Particularly preferred is that the (c) (meth)acrylic polymer does not contain sulfonic acid groups or at least partially neutralized sulfonic acid groups, such as in 2-acrylamide-2-methylpropane sulfonic acid and the salts thereof.

[0092] Even more preferred, the (c) (meth)acrylic polymer used in the present invention is not formed by use of sulfur or nitrogen containing ethylenically unsaturated monomers in the polymerization. Chemetall GmbH Dec. 05, 2025

[0093] Most preferred, the (c) (meth)acrylic polymer used in the present invention is a polymer which is formed from ethylenically unsaturated monomers consisting of aliphatic ethylenically unsaturated monomers. Thus, it is preferred that ethylenically unsaturated monomers, such as styrene are not contained employed in the polymerization of the (c) (meth)acrylic polymer.

[0094] In a preferred embodiment the (c) (meth)acrylic polymer consists of monomeric units which are formally derived from polymerizing monoethylenically unsaturated monomers selected from the group of monomers having the following formula (la):

[0095] H2C=CRb-(CO)-O-(LO)q[AO]nH (la), and wherein the AO unit stands for at least one alkylene oxide residue, selected from ethylene oxide residues and propylene oxide residues, preferably AO is an ethylene oxide unit; n being the number of AO units, preferably being in the range from 3 to 15 more preferred from 3 to 12, even more preferred from 3 to 10 and most preferred 3 to 8, and

[0096] Rbis H or CH3, preferably CH3; q = 0 or 1; and

[0097] LO is an ethylene oxide, propylene oxide or butylene oxide.

[0098] The (meth)acrylic polymer of formula (la) preferably possesses a number average molecular weight determined by gel permeation chromatography (GPC) in the range from 2000 Da to 10000 Da, more preferred 3000 Da to 8000 Da, even more preferred 3500 Da to 6000 Da, and most preferred 4000 Da to 5500 Da.

[0099] Furthermore the (meth)acrylic polymer of formula (la) preferably possesses a weight average molecular weight determined by gel permeation chromatography (GPC) in the range from 10000 Da to 40000 Da, more preferred 12000 Da to 35000 Da, even more preferred 14000 Da to 30000 Da, and most preferred 16000 Da to 25000 Da.

[0100] (d) Further Ingredients

[0101] Besides the mandatory ingredients, i.e., the (a) laminar clay mineral, the (b) zinc phosphate and the (c) (meth)acrylic polymer, further ingredients (d), which differ from (a), (b) and (c), may be employed in the aqueous surface conditioner concentrate of the present invention.

[0102] Such (d) further ingredients are preferably selected from the group of pH adjustment agents, serving to adjust the pH value to the desired range; preservatives, preventing the aqueous surface conditioner concentrate from fouling; chelators for complex formation with metal ions; organic rheology modifiers, further improving the rheological Chemetall GmbH Dec. 05, 2025 properties, such as increasing long term stability; and organic solvents. Most preferred amongst the aforementioned further ingredients are preservatives from a microbiological view and rheology modifiers from a technical view.

[0103] According to the present invention, the aqueous surface conditioner concentrate preferably has a pH value at 20 °C from 7 to 11 more preferred from 7.5 to 10.5, even more preferred from 7.8 to 9.8, and most preferred from 8.1 to 9.1 . The pH value can be determined by use of a calibrated pH electrode. An alkaline component may be present in the aqueous surface conditioner concentrate in an amount sufficient to adjust its pH value. Suitable alkaline components may include, for example, hydroxides, carbonates, orthophosphates, pyrophosphates, tripolyphosphate and silicates, each of sodium and potassium, or combinations thereof.

[0104] According to the present invention, the aqueous surface conditioner concentrate may also include a preservative. Suitable preservatives include, for example, 1 ,2-benzoisothazolin-3-one, 2-methyl-4-isothiazolin-3-one, or combinations thereof.

[0105] Examples of chelators are, for example, carboxylates such as tartrates, citrates or gluconates, acetate-based complexes such as ethylenediaminetetraacetate or nitrilotriacetate, phosphates such as pentasodium triphosphate or tetrapotassium pyrophosphate, phosphonates, polycarboxylates, the acids, esters, or salts of any of the aforementioned, or combinations thereof.

[0106] Organic solvents are also subsumed under (d) further ingredients, since the aqueous carrier medium used in the aqueous surface conditioner concentrate may comprise, besides water, also one or more water-dispersible or water-soluble, preferably water-soluble organic solvents. If such organic solvents are used, it is advisable to control the content of the organic solvent at a low level, preferably at most 10 wt.-%, more preferably at most 5 wt.-% based on the weight of the aqueous surface conditioner concentrate. In the present invention, the dispersion may be one which contains no carrier medium other than water. It is particularly preferred that the surface conditioner concentrate is free of organic solvents.

[0107] Particularly preferred as further optional ingredients (d) are organic rheology modifiers as for example, polyurethanes, acrylic polymers, lattices, styrene / butadiene, polyvinylalcohols, cellulose based materials such as carboxymethyl cellulose, methyl cellulose, (hydroxypropyl)methyl cellulose or gelatin, gums such as guar gum and xanthan gum, or combinations thereof. Particularly suitable are the afore-mentioned gums. The organic rheology modifiers may be employed, depending on their properties, in pure or pre-dissolved form.

[0108] Such further ingredients (d) as herein described above, may, however, be added to the aqueous surface conditioner concentrate after its dilution to the become the ready-to-use aqueous surface conditioner. Chemetall GmbH Dec. 05, 2025

[0109] Amounts of Ingredients in the Surface Conditioner Concentrate

[0110] The aqueous surface conditioner concentrate for metallic surfaces according to the invention preferably comprises

[0111] (a) one or more laminar clay minerals in an amount from 0.2 to 5.0 wt.-%, more preferred in an amount from 0.3 to 4.0 wt.-%, even more preferred in an amount from 0.5 to 2.0 wt.-%, and most preferred in an amount from 0.75 to 1.75 wt.-%,

[0112] (b) one or more zinc phosphates in an amount from 10.0 to 50.0 wt.-%, more preferred in an amount from 15.0 to 45.0 wt.-% even more preferred in an amount from 20.0 to 40.0 wt.-%, and most preferred in an amount from 25.0 to 35.0 wt.-%,

[0113] (c) one or more (meth)acrylic polymers as defined above in an amount from 1 .0 to 10.0 wt.-%, more preferred in an amount from 2.0 to 8.0 wt.-%, even more preferred in an amount from 3.0 to 7.0 wt.-%, and most preferred in an amount from 4.0 to 6.0 wt.-%; and

[0114] (d) one or more further ingredients selected from the group consisting of pH adjustment agents, preservatives, chelators, organic rheology modifiers, and organic solvents, even more preferred from the group consisting of preservatives and organic rheology modifiers, in an amount from 0.0 to 10.0 wt.-%, more preferred in an amount from 0.02 to 8.0 wt.-%, even more preferred in an amount from 0.04 to 7.0 wt.-%, and most preferred in an amount from 0.06 to 6.0 wt.-%; based on the total weight of the aqueous surface conditioner concentrate, the rest being water and (a), (b), (c), (d) and water summing up to 100 wt.-%.

[0115] The aqueous surface conditioner concentrate of the present invention serves to prepare a ready-to-use surface conditioner by diluting the concentrate with an aqueous carrier medium as described herein below.

[0116] The above ranges are valid, irrespective if just (a) one laminar clay material or a mixture of laminar clay materials is used, if just (b) one zinc phosphate or a mixture of zinc phosphates is used, if just (c) one (meth)acrylic polymer as defined above or a mixture of these is used; and if just (d) one further ingredient or mixture of further ingredients is used.

[0117] Particularly, the ranges also apply for any preferred ingredient or selection of ingredients under (a), (b), (c) and (d), irrespective of the level of preference, such as being more preferred, even more preferred, or most preferred.

[0118] With respect to the preferred embodiments, it is referred to the description of the ingredients above. Chemetall GmbH Dec. 05, 2025

[0119] Preparation of the Aqueous Surface Conditioner Concentrate

[0120] The method for preparing an aqueous surface conditioner concentrate (i.e., an aqueous dispersion) comprising the (a) one or more laminar clay minerals, the (b) one or more zinc phosphates and the (c) one or more (meth)acrylic polymer dispersed in an aqueous carrier medium, is not particularly limited. However, it is preferred to first mix the (a) laminar clay material and the (c) (meth)acrylic polymer and to add the (b) zinc phosphate afterwards. This guarantees for a better dispersibility.

[0121] For any of the (d) further ingredients it is preferred to add them as last ingredient(s).

[0122] Preferably the surface conditioner concentrate is subjected to a milling and / or grinding process after combining the (a) one or more laminar clay minerals, the (b) one or more zinc phosphates and the (c) one or more (meth)acrylic polymer. Milling and / or grinding are typically and preferably carried out on the aqueous concentrate in wet-milling processes, e.g., using bead mills or similar means.

[0123] Preferably the z-average particle size of the particles contained in the mixture of (a), (b) and (c), after the milling and / or grinding step, is below 1 m, more preferred below 800 nm, further preferred below 600 nm, even more preferred below 500 nm, and most preferred below 400 nm, as determined by dynamic light scattering. Further details as to the method used in determining the z-average particle size are described in the experimental part of the present invention.

[0124] Most preferred the further ingredients (d), particularly the one or more organic rheology modifiers are mixed in after the milling and / or grinding step.

[0125] Aqueous Surface Conditioner

[0126] To produce the ready-to-use aqueous surface conditioner, it is preferred to just dilute the surface conditioner concentrate with an aqueous carrier medium, preferably water. The water is selected from mains water, preferably having a low water hardness and deionized water. Preferably, deionized water is used.

[0127] Preferably, the surface conditioner concentrate is diluted in that 0.1 g to 8.0 g, more preferred 0.2 g to 7.0 g, even more preferred 0.3 g to 6.0 g of the aqueous surface conditioner concentrate are mixed in 1 liter of aqueous carrier medium, preferably water, to obtain the surface conditioner, which is than ready-to-use.

[0128] If contacting the surface conditioner in the surface activating method as described herein below is achieved by spraying, the surface conditioner concentrate is diluted in that 0.1 g to 5.0 g, more preferred 0.2 g to 4.0 g, even Chemetall GmbH Dec. 05, 2025 more preferred 0.3 g to 3.0 g of the aqueous surface conditioner concentrate are mixed in 1 liter of aqueous carrier medium, preferably water, to obtain the surface conditioner, which is than ready-to-use in spray application.

[0129] If contacting the surface conditioner in the surface activating method as described herein below is achieved by immersion, i.e. , dipping the substrate into an activation bath, the surface conditioner concentrate is diluted in that 0.3 g to 8.0 g, more preferred 0.4 g to 7.0 g, even more preferred 0.5 g to 6.0 g of the aqueous surface conditioner concentrate are mixed in 1 liter of aqueous carrier medium, preferably water, to obtain the surface conditioner, which is than ready-to-use in immersion application.

[0130] Optionally, however preferred, the surface conditioner may further be supplemented with additives such as water- soluble phosphates and / or water-soluble silicates, of alkali metals. Particularly preferred sodium and / or potassium salts of phosphates, preferably orthophosphates and pyrophosphates, and sodium and / or potassium salts of silicates, such as metasilicates. Such additives, preferably the afore-mentioned sodium and / or potassium orthophosphates, pyrophosphates, and silicates, such preferably metasilicates are preferably employed in the aqueous surface conditioner in form of an aqueous concentrate.

[0131] Preferably, such aqueous concentrates comprises alkali metal orthophosphates and alkali metal pyrophosphates, each calculated as P2O5, and each in an amount in the range from 1 wt.-% to 10 wt.-%, preferably 2 wt.-% to 8 wt.- % and most preferably 3 wt.-% to 6 wt.-%, based on the weight of such concentrate; and alkali metal silicates, preferably alkali metal metasilicates, calculated as SiC>2, in an amount in the range from 1 wt.-% to 10 wt.-%, preferably 2 wt.-% to 8 wt.-% and most preferably 3 wt.-% to 6 wt.-%, based on the weight of such concentrate. The alkali metals in the afore-mentioned orthophosphates, pyrophosphates and silicates are preferably sodium and / or potassium, preferably the weight ratio of K to Na being in the range from 30:1 to 5: 1, more preferred 20: 1 to 8:1 and most preferred 15: 1 to 10:1. The rest of the concentrate preferably being water.

[0132] Such concentrate of one or more additives is preferably employed in an amount of 0 g to 10.0 g, more preferred 0.2 g to 8.0 g, even more preferred 0.5 to 7.0 g in 1 liter of the aqueous carrier medium, which is used to dilute the surface conditioner concentrate.

[0133] Surface activating method according to the invention

[0134] Surface activation of various metal materials can be carried out by using the aqueous surface conditioner of the present invention as described above by contacting at least part of the surface of the metal material with the aqueous surface conditioner of the present invention.

[0135] The term "metal material” as used herein includes metals and their alloys. Metal materials, to which the above- mentioned surface conditioning is applied, are not particularly limited and the surface conditioning can be applied to various materials to which the chemical conversion treatment of phosphate is generally applied, for example, Chemetall GmbH Dec. 05, 2025 bare steel, cold-rolled steel, galvanized steel, such as electrogalvanized steel and hot-dip galvanized steel, aluminum or aluminum alloys, magnesium of magnesium alloys, such zinc magnesium. This method can also be suitably applied to the contact area between two or more types of metal materials. Thus, an application on multimetal substrates, i.e., preassemble substrates comprising two or more metals or alloys, is possible. The metal materials may have any shape, such as the shape of a vehicle body and parts thereof.

[0136] The metal material to be treated in accordance with the methods of the present invention may be cleaned with a cleaning composition to remove grease, dirt, or other extraneous matter and / or rinsed prior to applying the aqueous surface conditioner. Cleaning the surface of the metal material is often done by employing mild or strong alkaline cleaners, such as are commercially available and conventionally used in metal pretreatment processes. Following cleaning, the surface of the metal material optionally may be rinsed with tap water, deionized water, and / or an aqueous solution of rinsing agents to remove any residues of the cleaning composition.

[0137] According to the present invention, the aqueous surface conditioner can be contacted with the surface of the metal material by any conventional means, preferably by spraying or immersion techniques. The aqueous surface conditioner may be contacted with the substrate at a temperature in the range from 10 °C to 55 °C, more preferred in the range from 15 °C to 45 °C, most preferred 18 °C to 25 °C for any suitable period of time, preferably in the range from 5 seconds to 3 minutes, more preferred in the range from 10 seconds to 2 minutes.

[0138] Method of Surface Pre-treating a Metal Material

[0139] The above-described method of surface pre-treating a metal material, i.e., the surface pre-treatment method according to the invention comprises

[0140] (i) contacting at least part of the surface of the metal material with aqueous surface conditioner according to the invention to obtain an activated surface of the metal material (i.e., the surface activation method according to the invention); and subsequently

[0141] (ii) contacting the thus obtained activated surface with a chemical conversion treatment composition.

[0142] Step (i)

[0143] The surface activation treatment by use of the aqueous surface conditioner is carried out prior to a chemical conversion treatment. Thus, all details as herein above described for the surface activating method also apply here. Chemetall GmbH Dec. 05, 2025

[0144] Step (ii)

[0145] The term "conversion treatment” is also used in accordance with the afore-mentioned ISO 2080 and means a chemical or electrochemical process producing a superficial layer containing a compound of the substrate metal (often referred to as conversion coating) and an anion of an environment. The conversion coating as meant herein is preferably a phosphate conversion coating in accordance with ISO 2080, namely a layer of insoluble phosphates formed on a metal surface by using an agent containing ortho-phosphoric acid and / or ortho-phosphates.

[0146] The term "subsequently” between steps (I) and (II) does not exclude further steps such as rinsing steps with water or the like, preferably rinsing with water, preferably in one or more steps. Other steps prior to step (II) are also possible such as drying steps, while drying is not encouraged.

[0147] The chemical conversion treatment is preferably a phosphate conversion treatment which is not particularly limited, and various known methods, such as dipping treatment and spraying treatment, may be used. A plurality of them may be used in combination. The phosphate coating to be precipitated, is not particularly limited so long as a phosphate such as zinc phosphate with or without manganese and / or nickel, iron phosphate, manganese phosphate and / or zinc calcium phosphate is used.

[0148] The ii. step of contacting the metallic substrate with a chemical conversion treatment composition can be carried out by any common conversion treatment procedure. Most preferred are spray application and / or dip application, the latter one being most preferred. The duration of contacting the metallic substrate with the chemical pretreatment composition preferably ranges from 15 seconds to 8 min, more preferred 1 min to 5 min, most preferred 2 min to 4 min.

[0149] Generally, the temperature of the chemical conversion treatment composition used in step ii. is preferably in the range from 15 to 60 °C, more preferred 20 to 55 °C, even more preferred 25 to 50 °C.

[0150] Generally, any known chemical pre-treatment composition as used in metal surface finishing can be used in the ii. one or more chemical pre-treatment steps of the method of pre-treating a metallic substrate according to the present invention.

[0151] The chemical pre-treatment compositions used in the present invention are preferably acidic chemical pretreatment compositions.

[0152] Preferably the chemical pre-treatment compositions used in the method for coating according to the present invention are selected from phosphate conversion treatment compositions, including compositions which are layerforming and non-layer-forming. Chemetall GmbH Dec. 05, 2025

[0153] Examples for phosphate conversion treatment compositions are i. Ni- and / or Mn-containing and Ni- and / or Mn-free zinc phosphating compositions and trication phosphating compositions, i.e,, so-called "layer forming systems,” ii. compositions forming amorphous phosphate conversion coatings, i.e., so called "non-layer forming systems,” ill. phosphate conversion treatment compositions containing zinc ions and at least one of manganese ions and nickel ions including Ti / Zn based activation and optional zirconium-based passivation; and iv. compositions forming amorphous iron phosphate conversion coatings.

[0154] Amongst the zinc phosphating compositions, Ni-containing compositions may be employed. However, for environmental reasons, Ni-free zinc phosphating conversion treatment compositions are preferred, which contain Zn ions and Mn ions. Further variants of zinc phosphating conversion treatment compositions are the so-called trication phosphate conversion treatment compositions containing Zn, Mn and Ni ions. Phosphate conversion treatment compositions are for example available from Chemetall GmbH (Frankfurt, Germany) under the trademark Gardobond®.

[0155] Examples of suitable chemical conversion treatment compositions and their application conditions are, e.g., also described in US 2022 / 0119957 A1 and WO 2024 / 047074 A1 .

[0156] Optional Further Coating Layers

[0157] After the chemical conversion treatment, typically and preferably painting is carried out.

[0158] Typically, first an electrodeposition coating layer is formed by using electrodeposition coating materials, which are aqueous coating compositions being applied by dip coating, i.e., dipping the preferably chemically surface pretreated metal material into the electrically conductive, aqueous electrodeposition coating composition and applying a direct voltage between the substrate and a counter electrode. The electrodeposition coating composition is an anodic or cathodic electrodeposition coating composition, preferably a cathodic electrodeposition coating composition. Cathodic electrodeposition coating compositions are preferably selected from epoxy type and poly(meth)acrylate-type electrodeposition coating compositions.

[0159] Secondly, a primer coating material, one or more basecoat coating materials and one or more clearcoat coating materials, are preferably applied onto the electrodeposition coating layer in the afore-mentioned order. The primer coating materials, basecoat coating materials and clearcoat coating materials can be one-pack or two-pack coating materials, aqueous or solvent-borne. Chemetall GmbH Dec. 05, 2025

[0160] It is also possible to apply powder coating material after the chemical conversion treatment.

[0161] Use of the aqueous surface conditioner of the invention Finally, the invention provides the use of the aqueous surface conditioner as defined herein-above as a surface activating composition of a metal material prior to a chemical conversion treatment step. The metal material being as described herein above and the chemical conversion treatment being as described herein above.

[0162] Now, the present invention will be described in further detail with reference to Examples.

[0163] Chemetall GmbH Dec. 05, 2025

[0164] EXAMPLES

[0165] Determination of Substance and Composition Parameters

[0166] Determination of the averaged molecular weights

[0167] The determination of the number average and weight average molecular weights of the polymers used herein, and particularly the (meth)acrylic polymers (c), were carried out by gel permeation chromatography at 35 °C, using a 0.07 M aqueous solution of sodium hydrogen phosphate as eluent, a polyacrylic acid standard.

[0168] Determination of the z-average particle size of the solids in the concentrate

[0169] The z-average particle size of the solid particles contained in the aqueous surface conditioner concentrates of the invention after milling and / or grinding are determined by dynamic light scattering using a 0.3 wt.-% dispersion of the concentrate in water at 25 °C. The instrument used is a Zetasizer Ultra, commercially available from Malvern Panalytical.

[0170] Free Acid “FA” and Free Acid-KCI “FA-KCI”

[0171] For determination of the free acid-KCI, 10 ml of the chemical conversion treatment composition is pipetted into a suitable vessel, such as a 300 ml conical flask, and diluted with 50 ml of 2 M KCI solution. Titration then takes place, using a pH meter and an electrode, with 0.1 M NaOH to a pH of 4.0. The quantity of 0.1 M NaOH consumed in this titration, in ml per 10 ml of the composition, gives the value of the free acid-KCI (FA-KCI) in points. If no complex fluorides are contained, the Free Acid "FA” is determined in the same way except for using deionized water instead of the KCI solution. See also: W. Rausch "Die Phosphatierung von Metallen”, Eugen G. Leuze Verlag, 3rd edition, 2005, chapter 8.1 , pp. 333-334).

[0172] Free Acid (Diluted) (FA (dil.))

[0173] (cf. W. Rausch "Die Phosphatierung von Metallen”, Eugen G. Leuze Verlag, 3rd edition, 2005, chapter 8.1 , pp. 333- 334)

[0174] For determination of the free acid (diluted), 10 ml of the chemical conversion treatment composition is pipetted into a suitable vessel, such as a 300 ml conical flask. 150 ml of deionized water is then added. Using a pH meter and an electrode, titration takes place with 0.1 M NaOH to a pH of 4.2. The quantity of 0.1 M NaOH consumed in this titration, in ml per 10 ml of the diluted composition, gives the value of the free acid (diluted) (FA (dil.)) in points. Chemetall GmbH Dec. 05, 2025

[0175] Total Acid Fischer (TAF)

[0176] (cf. W. Rausch "Die Phosphatierung von Metallen”, Eugen G. Leuze Verlag, 3rd edition, 2005, chapter 8.2, pp. 334- 336)

[0177] Following determination of the free acid (diluted), the diluted composition of the invention, after addition of potassium oxalate solution, is titrated, using a pH meter and an electrode, with 0.1 M NaOH to a pH of 8.9. The consumption of 0.1 M NaOH in ml per 10 ml of the diluted composition gives here the Total Acid Fischer (TAF) in points.

[0178] Total Acid (TA) or Total Acid-KCI (TA-KCI)

[0179] (cf. W. Rausch "Die Phosphatierung von Metallen”, Eugen G. Leuze Verlag, 3rd edition, 2005, chapter 8.3, pp. 336- 338)

[0180] The total acid or— where complex fluorides are present in the phosphating bath— total acid-KCI is the sum of the divalent cations present and also free and bonded phosphoric acids (the latter being phosphates). It is determined by the consumption of 0.1 M NaOH using a pH meter and an electrode. For this purpose, 10 ml of the composition of the invention is pipetted into a suitable vessel, such as a 300 ml conical flask, and diluted with 50 ml of deionized water. Where the composition of the invention comprises complex fluorides, the sample is instead diluted with 50 ml of 2 M KCI solution. This is followed by titration with 0.1 M NaOH to a pH of 8.9. The consumption in ml per 10 ml of the diluted composition corresponds here to the points number of the total acid (TA) or of total acid-KCI (TA- KCI).

[0181] Acid Value (S Value, also sometimes denoted as A Value)

[0182] (cf. W. Rausch "Die Phosphatierung von Metallen”, Eugen G. Leuze Verlag, 3rd edition, 2005, chapter 8.4, p. 338)

[0183] The acid value (S value) represents the ratio FA:TAF or FA-KCI:TAF and is obtained by dividing the value for the free acid (FA) or for the free acid-KCI (FA-KCI) by the value for the Total Acid Fischer (TAF). Chemetall GmbH Dec. 05, 2025

[0184] Test Methods

[0185] Copper Accelerated Salt Spray Test (CASS Test)

[0186] The CASS test is used for determining the corrosion resistance of a coating on a substrate. In accordance with DIN EN ISO 9227 (07-2017) the samples under analysis are in a chamber in which there is continuous misting of a 5% NaCI solution, the salt solution being admixed with acetic acid (pH reduction to 3.1 to 3.3) and copper chloride, at a temperature of 50 °C over a duration of 96, 168, 240 and 504 hours, respectively, with controlled pH value. The spray mist deposits on the samples under analysis, covering them with a corrosive film of salt water. Prior to the CASS test, the coating on the samples for investigation is scored down (i.e. scribed) to the substrate with a tool having a blade incision of 1 mm (Corrocutter 639 from Erichsen with a Sikkens 1 mm-blade). The samples are investigated for their level of under-film corrosion in accordance with DIN EN ISO 4628-8 (03-2013), since the substrate corrodes along the scribe line during the CASS test. As a result of the progressive process of corrosion, the coating is undermined to a greater or lesser extent during the test. The extent of undermining in [mm] is a measure of the resistance of the coating. The values are average values of 3 panels.

[0187] VDA Test

[0188] The VDA test was carried out in accordance with „VDA-Prufblatt 233-102”.

[0189] The respective coating on the samples under investigation is scored down to the substrate with a bladed incision prior to the implementation of the alternating climate test, thus allowing the samples to be investigated for their level of under-film corrosion (undermining) to DIN EN ISO 4628-8 (03-2013), since the substrate corrodes along the score line during the performance of the alternating climate test. As a result of the progressive process of corrosion, the coating is undermined to a greater or lesser extent during the test. The degree of undermining in [mm] is a measure of the resistance of the coating to corrosion. The average undermining level stated in the results later on below represents the average value of the individual values obtained by assessing every 5 to 10 mm at regular intervals and the average value is the result. 5 mm at the beginning and end of the scribe are not included

[0190] Value “c” is the value for corrosion in accordance to DIN EN ISO 4628-8 and shows the corrosion attack in specific corrosion tests where an "underrusting” happens. Cyclic tests have often “c” = “d.” Value “d” is the value for delamination in accordance to DIN EN ISO 4628-8, which can be found more often in the neutral salt spray test. The NSS acc.accoring to DIN EN ISO 9227 shows less corrosion attacks due to a high humid continuous salt environment. Chemetall GmbH Dec. 05, 2025

[0191] Climate Change Test PV 1210 (Volkswagen PV 1210 Test; date: 2016-02)

[0192] This climate change test is used to determine the corrosion resistance of a coating on a substrate. The climate change test is carried out in 30 or more cycles. Prior to the PV1210 test, the coating of the specimens to be tested is scored down to the substrate with a scribing tool (see above "Corrocutter”) before the climate change test is performed, the specimens can be tested for their degree of under-film corrosion in accordance with DIN EN ISO 4628-8 (03-2013), since the substrate corrodes along the scoring line during the climate change test. As corrosion progresses, the coating is more or less infiltrated during the test. The degree of undermining in [mm] is a measure of the resistance of the coating. The values are average values of 3 panels.

[0193] One cycle (24 hours) here consists of 4 hours of salt spray mist testing as per DIN EN ISO 9227 NSS (2017-07), 4 hours aging at room temperature / room humidity approx. 23°C / 50% relative humidity and 16 hours at 40°C / approx. 100% relative humidity in accordance to DIN EN ISO 6270-2 CH (2018-04). At weekends there is an aging at room temperature / room humidity approx. 23°C / 50% relative humidity 30 cycles therefore correspond to a total duration of 42 days (= 6 weeks).

[0194] PV 3.15.3 test (Volkswagen PV 3.15.3 test; date: 2016-12)

[0195] The test is a cyclic treatment test of a coated, down-to-the-metallic-base-material-scribed substrate, which comprises a combination of different climatic and corrosive loads, including salt spray treatment, standard atmosphere aging and heat humidity aging as set out in detail in the above-mentioned standard. A cycle is 24 hours, 15 cycles are carried out before evaluation.

[0196] Stone Chip resistance test

[0197] Stone chip resistance is determined in accordance to DIN EN ISO 20567-1.

[0198] Maximum sedimentation rate (LUMiSizer Measurement)

[0199] The method serves to characterize the sedimentation process of a dispersed material. For this purpose, the sample is accelerated in an optical cuvette centrifuge and thus experiences a centrifugal force. The effect of this is separation of the dispersed sample constituents in accordance with their density. This separation process can be followed along a cuvette as a function of time. The resulting rate profiles characterize the mechanism of sedimentation (when the density of the dispersed particles is greater than that of the surrounding dispersant) or of creaming (when the density of the dispersed particles is less than that of the surrounding dispersant). Chemetall GmbH Dec. 05, 2025

[0200] In the case of sedimentation, the rate at which the phase boundary between sediment and clear supernatant changes position can serve as a quantification of the sedimentation process: A sample wherein the position of the phase boundary barely changes within a given time has much greater sedimentation stability than a sample where the phase boundary undergoes distinct movement within the same period of time.

[0201] Since the sample has still not been subjected to any centrifugal force prior to commencement of the measurement, and therefore the homogeneity of the sample is at the maximum possible level, the sedimentation rate will be at its highest directly on commencement of or at least within the initial period of measurement and will then drop gradually.

[0202] The actual measurements proceed as follows:

[0203] The sample is analyzed in an optical cuvette centrifuge (LUMiSizer 6110-74) with regard to sedimentation rates over a period of 50,000 seconds and the maximum sedimentation rate within this period is evaluated (PA cuvettes with optical path length 2 mm, measurement temperature 25°C, wavelength 870 nm, 134 g, 1000 rpm).

[0204] Preparation of Surface Conditioner Concentrates SCC

[0205] Inventive Surface Conditioner Concentrates ISSC1, ISSC2, and ISSC3

[0206] The inventive surface conditioner concentrate ISSC1 was prepared by weighing in the water (position 1 ) and while high-speed mixing, adding the ingredients as shown in Table 1, in the respective amounts, one after each other as indicated by their positions (positions 2, 3, 5 and 6). The thus obtained composition was ground using a mill. The pH value of the composition at 20 °C was 8.6 ± 0.5.

[0207] The inventive surface conditioner concentrates ISCC2 and ISCC3 were prepared in the same manner, but with differing amounts of IP1, the difference being balanced by addition of more or less amounts of water, respectively.

[0208] The inventively used polymer IP1 (position 3) is a poly (meth)acrylic acid wherein the (meth)acrylic acid functions comprise polyethylene oxide chains.

[0209] The number-average molecular weight Mnand weight -average molecular weight Mwof IP1 were determined by GPC as lined out above. The Mnwas 4800 Da, the Mwwas 20400 Da.

[0210] Comparative Surface Conditioner Concentrate CSCC1

[0211] The comparative surface conditioner concentrate CSCC1 was prepared by weighing in the water (position 1 ) and while high-speed mixing, adding the ingredients as shown in Table 1, in the respective amounts, one after each Chemetall GmbH Dec. 05, 2025 other as indicated by their positions (positions 2 and 4 to 6). The thus obtained composition was ground using a mill. The pH value of the composition at 20 °C was 8.6 ± 0.1.

[0212] The polymer CP1 (position 4) as used in the comparative surface conditioner concentrate is a copolymer composed of 40% by weight of acrylic acid and 60% by weight of 2-acrylamide-2-methylpropane sulfonic acid.

[0213] The number-average molecular weight Mnand weight -average molecular weight Mwof CP1 were determined by GPC as lined out above. The Mnwas 2550 Da, the Mwwas 8330 Da.

[0214] Table 1

[0215] Preparation of Surface Conditioner SC from the Surface Conditioner Concentrates SCC

[0216] The ready-to-use surface conditioners SC (ISC1 , ISC2, ISC3, and CSC1) were prepared by diluting 1 gram of the respective surface conditioner concentrate SSC in 1 L of deionized water and subsequently the dilutions were supplemented with 3 g of an aqueous concentrate AC comprising (weight ratio K / Na 15:1-10:1 , 4.5 ± 1.5 wt.-% orthophosphate (calculated as P2O5), 4.5 ± 1.5 wt.-% pyrophosphate (calculated as P2O5), 4.5 ± 1.5 wt.-% metasilicate (calculated as SiO2), and 55 wt.-% deionized water). The amounts are shown in Table 2.

[0217] Chemetall GmbH Dec. 05, 2025

[0218] Table 2

[0219] Preparation of rinsed, pre-treated and coated substrates

[0220] Test panels of various metallic substrates (steel, cold rolled steel, electrolytically galvanized steel, hot-dip galvanized steel, and aluminum) were first cleaned. This was done by spraying for 120 seconds, followed bv dipping for 180 seconds (alkaline (pH value = 10 to 11) aqueous solution (60 °C) comprising a surfactant plus a detergent builder comprising borate, silicate and phosphate).

[0221] The panels were then spray-rinsed with mains water at 20 °C for 60 seconds.

[0222] Subsequently, they were subjected to the surface conditioners as shown in Table 2, for 40 seconds by dipping.

[0223] Subsequently, phosphating took place using acidic aqueous phosphating solutions PL1 to PL4 as indicated in Table 3, at 53 °C for 180 seconds by dip-application.

[0224] After phosphating, the panels were again spray-rinsed with mains water at 20 °C for 60 seconds.

[0225] The panels were then rinsed with deionized water (conductivity <20 pS / cm) at 20 °C by dipping for 30 seconds and dried in a drying oven at 110 to 120° C for 10 min.

[0226] The different phosphated test panels were analyzed using XRF (x-ray fluorescence analysis) and gave the mean zinc phosphate coat weights set out in Table 4. Chemetall GmbH Dec. 05, 2025

[0227] Table 3

[0228] *) calculated as Zna(PO4 In Tables 5, 6, 7, and 8, respectively, inventive, and comparative surface conditioner treatments were compared on different metallic substrates, namely aluminum (Table 5), electrogalvanized steel (Table 6), hot-dip galvanized steel (Table 7), and cold rolled steel (Table 8), with respect to their effect on corrosion resistance, particularly corrosive undermining, and their stone chip resistance. In each case, after surface conditioner treatment, zinc phosphating, as described above, an e-coating was applied.

[0229] In the following Tables 5 to 10, in the inventive examples IE the combination of ICS1 and PL1 was used, and in comparative example CE1 the combination CSC1 and PL4 was used. The e-coat applied was CathoGuard® 800 cured at a peak metal temperature of 175 °C for 15 minutes. Chemetall GmbH Dec. 05, 2025

[0230] Table 5 - CASS test: aluminum (AA6014) I e-coat (CG 800)

[0231] Table 6 - PV3.15.3 test: electrogalvanized steel I e-coat (CG 800)

[0232] Table 7 - PV 3.15.3 test: hot-dip galvanized steel I e-coat (CG 800)

[0233] Table 8 - PV 1210 test: cold rolled steel I e-coat (CG 800)

[0234] In Tables 9 and 10, respectively, inventive, and comparative surface conditioner treatments were compared on different metallic substrates, namely electrogalvanized steel (Table 9) and hot-dip galvanized steel (Table 10), with respect to their effect on corrosion resistance, particularly corrosive undermining. In each case, after surface conditioner treatment, zinc phosphating, e-coating, and three-layer paint coating (TLP coating: consisting of filler + basecoat + clear coat) were applied as described above. In the TLP coating a water-based filler on the basis of polyester and polyurethane binders (color: anthracite), an obsidian black ColorBrite ES basecoat (from BASF Coatings GmbH) and a two-pack high-solids clear coat were used. Chemetall GmbH Dec. 05, 2025

[0235] As can be learned from the Examples there is are considerable improvements on galvanized steel panel (electrogalvanized and hot-dip galvanized steel panel), while on aluminum no significant changes were observable with respect to filiform corrosion. Table 9 - VDA test: electrogalvanized steel I e-coat (CG 800) + TLP

[0236] Table 10 - VDA test: hot-dip galvanized steel / e-coat (CG 800) + TLP In Table 11 the LUMiSizer measurements are shown, indicating the much better sedimentation stability of the inventive surface conditioner ISC1 compared to the comparative surface conditioner CSC2.

[0237] Table 11 - LUMISizer Measurements

Claims

1. Chemetall GmbH Dec. 05, 2025CLAIMS1 . An aqueous surface conditioner concentrate for metallic surfaces comprising(a) one or more laminar clay minerals;(b) one or more zinc phosphates; and(c) one or more (meth)acrylic polymers, in an aqueous carrier medium, wherein the (c) (meth)acrylic polymers comprise a poly (meth)acry lie backbone and side chains comprising hydroxyl terminated poly (alky lene oxide) chains.

2. The aqueous surface conditioner concentrate of claim 1 , wherein the one or more laminar clay materials are selected from the group of smectite group minerals, preferably montmorillonite, beiderite, saponite, and hectorite.

3. The aqueous surface conditioner concentrate of claim 2, wherein the hectorite is a natural or synthetic hectorite.

4. The aqueous surface conditioner concentrate according to any one or more of the preceding claims, wherein the one or more zinc phosphates are selected from the group non-hydrated or hydrated zinc phosphates.

5. The aqueous surface conditioner concentrate according to any one or more of the preceding claims, wherein the hydroxy terminated poly(alkylene oxide) chains of the one or more (meth)acrylic polymers are depicted by -[A0]nH, wherein A stands for an alkylene residue, preferably alkylene residue selected from ethylene residues (CH2CH2) and propylene residues (CHR'CHR”), with one of R' or R” being H and one of R' or R” being CH3, and n being the number of AO units, preferably n being in the range from 3 to 15 more preferred from 3 to 12, even more preferred from 3 to 10 and most preferred 3 to 8.

6. The aqueous surface conditioner concentrate according to any one or more of the preceding claims, wherein the hydroxy terminated poly (alkylene oxide) chains on average at least comprise 50 mole-% of the n AO units being ethylene oxide units (EO), more preferred at least 60 mole-% of the n AO units being EO units, even more preferred at least 70 mole-% being EO units, and most preferred at least 80 mole-% of the AO units being EO units.Chemetall GmbH Dec. 05, 20257. The aqueous surface conditioner concentrate according to any one or more of the preceding claims, wherein the poly (meth)acrylic backbone of the one or more (meth)acrylic polymers comprises or preferably preferred consists of a chain, formed by polymerization of monoethylenically unsaturated monomers.

8. The aqueous surface conditioner concentrate according to any one or more of the preceding claims, wherein the (c) (meth)acrylic polymer comprises monomeric units which are formally derived from polymerizing monoethylenically unsaturated monomers selected from the group of monomers having the following formula (I):H2C=CRb-(CO)p-O-(LO)qRa(I), and whereinRais selected from H and a residue of formula [AO]nH, wherein A stands for an alkylene residue, preferably an alkylene residue selected from ethylene residues and propylene residues, n being the number of AO units, preferably being in the range from 1 to 12 more preferred from 2 to 10, even more preferred from 3 to 8 and most preferred 3 to 6, andRbis H or CH3; p = 0 or 1 ; q = 0 or 1 ;LO is an ethylene oxide, propylene oxide or butylene oxide; with the provisos that at least part, preferably all of residues Raare residues of formula [AO]nH.

9. The aqueous surface conditioner concentrate according to claim 8, wherein the (c) (meth)acrylic polymer consists of monomeric units which are formally derived from polymerizing monoethylenically unsaturated monomers selected from the group of monomers having the following formula (la):H2C=CRb-(CO)-O-(LO)q[AO]nH (la), and wherein the AO unit stands for at least one alkylene oxide residue, selected from ethylene oxide residues and propylene oxide residues, preferably AO is an ethylene oxide unit; n being the number of AO units, preferably being in the range from 3 to 15 more preferred from 3 to 12, even more preferred from 3 to 10 and most preferred 3 to 8, andRbis H or CH3, preferably CH3; q = 0 or 1; andChemetall GmbH Dec. 05, 2025L0 is an ethylene oxide, propylene oxide or butylene oxide.

10. The aqueous surface conditioner concentrate according to any one or more of the preceding claims, characterized in that it comprises one or more further ingredients (d) selected from the group consisting of pH adjustment agents, preservatives, chelators, organic rheology modifiers, and organic solvents, even more preferred from the group consisting of preservatives and organic rheology modifiers, preferably a rheology modifier selected from gums, which might be pre-dissolved.

11. The aqueous surface conditioner concentrate according to any one or more of the preceding claims, characterized in that the z-average particle size of the solid particles therein is below 1 m, as determined by dynamic light scattering.

12. The aqueous surface conditioner concentrate for metallic surfaces according to one or more of claims 1 to 11 comprises(a) one or more laminar clay minerals in an amount from 0.2 to 5.0 wt.-%, more preferred in an amount from 0.3 to 4.0 wt.-%, even more preferred in an amount from 0.5 to 2.0 wt.-%, and most preferred in an amount from 0.75 to 1 .75 wt.-%,(b) one or more zinc phosphates in an amount from 10.0 to 50.0 wt.-%, more preferred in an amount from 15.0 to 45.0 wt.-% even more preferred in an amount from 20.0 to 40.0 wt.-%, and most preferred in an amount from 25.0 to 35.0 wt.-%,(c) one or more (meth)acry lie polymers as defined above in an amount from 1 .0 to 10.0 wt.-%, more preferred in an amount from 2.0 to 8.0 wt.-%, even more preferred in an amount from 3.0 to 7.0 wt.-%, and most preferred in an amount from 4.0 to 6.0 wt.-%; and(d) one or more further ingredients selected from the group consisting of pH adjustment agents, preservatives, chelators, organic rheology modifiers, and organic solvents, even more preferred from the group consisting of preservatives and organic rheology modifiers, in an amount from 0.0 to 10.0 wt.-%, more preferred in an amount from 0.02 to 8.0 wt.-%, even more preferred in an amount from 0.04 to 7.0 wt.-%, and most preferred in an amount from 0.06 to 6.0 wt.-%; based on the total weight of the aqueous surface conditioner concentrate, the rest being water and (a), (b), (c), (d) and water summing up to 100 wt.-%.

13. An aqueous surface conditioner, comprising 0.1 g to 8 g of the aqueous surface conditioner concentrate as defined in any one or more of the preceding claims per 1 liter of an aqueous carrier medium.

14. The aqueous surface conditioner of claim 13, further comprising at least one sodium or potassium salt selected from silicates and phosphates, the phosphates preferably being selected from orthophosphates and pyrophosphates and the silicates preferably being selected from metasilicates.Chemetall GmbH Dec. 05, 202515. A method of surface activating a metal material prior to a chemical conversion treatment, the method comprising the step of(I) contacting at least part of the surface of the metal material with the aqueous surface conditioner as defined in any one or more of claims 13 and 14.

16. A method of surface pre-treating a metal material, the method comprising the steps of(I) contacting at least part of the surface of the metal material with the aqueous surface conditioner as defined in any one or more of claims 13 or 14 to obtain an activated surface of the metal material; and subsequently(II) contacting the thus obtained activated surface with a chemical conversion treatment composition, preferably a phosphate conversion treatment composition.

17. Use of the aqueous surface conditioner as defined in claim 13 or 14 as a surface activating composition of a metal material prior to a chemical conversion treatment step.

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