Phosphate-free cleaning agent for metallic surfaces with reduced pickling corrosion.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- CHEMETALL GMBH
- Filing Date
- 2020-03-20
- Publication Date
- 2026-08-03
Smart Images
Figure 0007898854000001 
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Abstract
Description
Technical Field
[0001] The present invention relates to water-based alkaline cleaning agent concentrates and to cleaning agents for metallic surfaces with reduced pitting corrosion, said concentrates or said cleaning agents acting without the use of phosphates, and the invention relates to a method of anticorrosively treating metallic surfaces including the corresponding cleaning process, metallic surfaces obtained by said method, and methods of using these in branches of the metalworking industry.
Background Art
[0002] Detergent products containing phosphates have long been used as standard in industrial metal cleaning for their action of accelerating degreasing. Furthermore, in addition to their degreasing action, phosphates offer the advantage of acting as complexing agents for interfering ions such as magnesium or calcium.
[0003] For example, the anticorrosive pretreatment of metal strips and metallic parts in vehicle construction or in normal industry uses aqueous cleaning systems and conversion solutions with a pH in a considerably acidic range or in an alkaline range.
[0004] Thus, during the cleaning itself, so-called pitting attack occurs, which can attack not only the oxide film but also the base material, and its morphology can be adversely affected. This can act on the precipitation of the subsequent conversion coating and can then lead to a reduction in the adhesion of the resulting coating, especially of cathodic electrodeposition materials, and can thus adversely affect corrosion control.
[0005] For this reason, standard phosphate-containing products are often combined with silicate compounds as corrosion inhibitors so that, during the cleaning operation, materials sensitive to attack, such as (zinc) plated steel, aluminum or aluminum-containing substrates, are protected from excessive stress.
[0006] However, at pH levels below 11, silicate compounds, such as potassium and sodium silicates, as well as potassium and sodium aqueous glass, tend to precipitate and thus lose their activity, and thus may further form a crust in the washing bath or a dry precipitate on the metal surface being treated, which is difficult to remove and visually unsightly. Therefore, such compounds are not commonly used today as pickling inhibitors in alkaline washing systems.
[0007] Meanwhile, boron compounds, such as boric acid, or sodium borate or potassium borate, have been used as substitutes for silicate compounds, particularly in the case of aluminum and galvanized steel.
[0008] However, in recent years, there has been a clear trend toward safer and more environmentally friendly detergent compositions. The sources driving this trend are, firstly, legal regulations in various countries (e.g., China) or regions that increasingly prohibit the use of certain ingredients, including phosphates and complexing agents such as EDTA, and secondly, the growing environmental and safety awareness of users.
[0009] This trend is also reflected in conversion systems, with a greater focus on thin, organosilane-based film systems, such as Oxsilan® (Chemetall GmbH, Germany). Like zinc phosphate treatment, these systems act as aqueous conversion systems, but they offer clear advantages in terms of more environmentally friendly products, environmental considerations, and the prohibition of raw materials such as nickel or phosphate.
[0010] Therefore, aqueous cleaning agents are now required to exhibit high compatibility with established conversion processes, such as compatibility with 3-cation (trication) phosphate treatment, as well as nickel-free zinc phosphate treatment, and especially compatibility with the thin film systems mentioned above. Consequently, there is a demand for producing metal surfaces that are optimal for all types of conversion treatments.
[0011] Patent document 1 (US9567552B2) describes a phosphate-free cleaning agent in which a long-chain polyacrylate is used as a corrosion inhibitor. This cleaning agent is suitable for treating aluminum / aluminum alloys, but is not suitable for multimetal systems of the kind commonly used in the automotive industry, for example. The compatibility of the cleaning agent with subsequent thin film coatings based on organosilanes or 3-cationic phosphate treatment systems is not described. [Prior art documents] [Patent Documents]
[0012] [Patent Document 1] US9567552B2 [Overview of the Initiative] [Problems that the invention aims to solve]
[0013] Accordingly, an object of the present invention is to provide a water-based detergent concentrate, and a water-based detergent for corresponding metallic surfaces that, firstly, acts without the use of phosphates, and at the same time, combines a harmonized pickling attack with good cleaning performance, and secondly, prepares a metallic surface that is optimal for any type of conversion treatment. [Means for solving the problem]
[0014] The purpose is to provide a water-based alkaline cleaning agent concentrate for manufacturing cleaning agents for metallic surfaces, a) At least one (meth)acrylic acid homopolymer having a mass-average molar mass in the range of 3000 to 19000 g / mol, b) At least one (meth)acrylic acid copolymer having a mass-average molar mass in the range of 50,000 to 100,000 g / mol, This was achieved by a detergent concentrate containing at least one copolymer of at least one (meth)acrylic acid copolymer with at least one monomer having at least two acidic groups selected from the group consisting of (meth)acrylic acid, a vinyl group, and a carboxylic acid group and a sulfonic acid group. [Modes for carrying out the invention]
[0015] The polymers of components a) and b) are used here as phosphate substitutes in the detergent concentrate of the described invention. Surprisingly, the performance of a standard phosphate-containing detergent could not be achieved with the polymers alone. Instead, equivalent results could only be achieved by using a polymer mixture of components a) and b).
[0016] The polymer in component a) contains a relatively short-chain (meth)acrylic acid homopolymer, which combines prevention of pickling attack with a moderate cleaning effect. In contrast, the polymer in component b) is a specific long-chain (meth)acrylic acid copolymer, and due to its strong complexing properties and associated strong pickling attack, it acts as a cleaning accelerator, and its cleaning performance is equivalent to that of phosphates used as a standard.
[0017] The mass-average molar mass of the polymers of components a) and b) is consistently determined here using GPC with an eluent aqueous solution. G el P ermeation C Chromatography (gel permeation chromatography) is used for measurement. In this case, the column is calibrated using polystyrene sulfonate with a narrow molecular weight distribution.
[0018] Definition: Here, the term "water-based" is understood to mean that the corresponding composition, which may include both dissolved and dispersed components, for example a detergent concentrate or a detergent, is composed of, for example, at least 50% by mass of water, preferably at least 55% by mass of water.
[0019] Here, "detergent" and "detergent composition" are used as synonyms. More specifically, the detergent or detergent composition may be a detergent solution.
[0020] "(Meth)acrylic acid" always represents methacrylic acid, acrylic acid, or both here. Further, it is always intended to also include the deprotonated forms, and thus the conjugate bases of methacrylic acid or acrylic acid respectively.
[0021] Thus, a "(meth)acrylic acid homopolymer" may be a polymer containing only methacrylic acid, only acrylic acid, or both methacrylic acid and acrylic acid as monomer units, but no other monomer units are applicable.
[0022] The same applies to "(meth)acrylic acid copolymers". This term may include only methacrylic acid, only acrylic acid, or both methacrylic acid and acrylic acid as monomer units, but always has additional monomers that are not methacrylic acid or acrylic acid. Here, it is also intended that at least one monomer having a vinyl group and at least two acidic groups includes all deprotonated forms of the corresponding acidic groups.
[0023] When in each case in this application the expression "calculated as X" where X is a specifically identified chemical compound is used in relation to a concentration on a mass basis (wt%), this has the following meaning: if a replacement chemical compound (other than X) is used, this should be used as the molar concentration calculated from the specifically given mass concentration (wt%) for X, taking into account the molar mass.
[0024] The component a) of the detergent concentrate of the present invention preferably comprises at least one (meth)acrylic acid homopolymer, and more preferably at least one acrylic acid homopolymer.
[0025] The at least one (meth)acrylic acid homopolymer of component a) preferably comprises, and more preferably comprises, at least one (meth)acrylic acid homopolymer having a mass-average molar mass in the range of 5,000 to 15,000 g / mol, particularly preferably in the range of 6,000 to 12,000 g / mol, and most preferably in the range of 7,000 to 9,000 g / mol, calculated as polyacrylic acid.
[0026] The phrase "calculated as polyacrylic acid" should be understood as follows: Even if at least one (meth)acrylic acid homopolymer of component a) is not polyacrylic acid, or is not exclusively polyacrylic acid, for the purpose of calculating the concentration, it is nevertheless assumed that all monomer units (100 mol%) of at least one (meth)acrylic acid homopolymer of component a) are acrylic acid.
[0027] The at least one (meth)acrylic acid homopolymer of component a) particularly preferably includes, and more preferably, at least one (meth)acrylic acid homopolymer having a mass-average molar mass in the range of 5,000 to 15,000 g / mol, particularly preferably in the range of 6,000 to 12,000 g / mol, and very preferably in the range of 7,000 to 9,000 g / mol, calculated as polyacrylic acid.
[0028] At least one (meth)acrylic acid homopolymer of component a) is added to the detergent concentrate, preferably as a salt, more preferably as an alkali metal salt, and particularly preferably as a sodium salt. In terms of the alkalinity of the detergent concentrate obtained, the sodium salt is particularly advantageous.
[0029] A particularly suitable example is polyacrylic acid with a mass-average molar mass of approximately 8000 g / mol (available as Sokalan® PA 30 CL, BASF SE, from Germany).
[0030] The component b) of the detergent concentrate of the present invention comprises at least one (meth)acrylic acid copolymer of (meth)acrylic acid and at least one monomer having a vinyl group and at least two acidic groups selected from the group consisting of a carboxylic acid group and a sulfonic acid group, preferably a linear copolymer.
[0031] On the one hand, (meth)acrylic acid units and on the other hand, monomer units having at least two acidic groups are arranged here preferably in an alternating arrangement. In principle, however, the corresponding block copolymers and random copolymers are suitable. At least one (meth)acrylic acid copolymer preferably does not contain other monomer units, more preferably does not contain vinyl acetate or vinyl alcohol, and more specifically still does not contain vinyl acetate units.
[0032] The (meth)acrylic acid units constitute preferably 35 to 65 mol%, particularly preferably 40 to 50 mol%, and very preferably 45 to 55 mol% of at least one (meth)acrylic acid copolymer of component b), while the monomer units having at least two acidic groups constitute preferably 65 to 35 mol%, particularly preferably 60 to 40 mol%, and very preferably 55 to 45 mol% of at least one (meth)acrylic acid copolymer of component b), and the above mol% preferably total 100 in each case.
[0033] According to the first preferred embodiment, the at least one (meth)acrylic acid copolymer of component b) comprises, preferably alternating, copolymers of (meth)acrylic acid and at least one, preferably exactly one monomer comprising a vinyl group and at least two, preferably exactly two, carboxylic acid groups.
[0034] Here, the at least one monomer comprising a vinyl group and at least two carboxylic acid groups is preferably selected from the group consisting of vinyldicarboxylic acids, more preferably from the group consisting of maleic acid and fumaric acid, and more preferably from maleic acid.
[0035] Here, it is noted that "maleic acid" is understood to include maleic anhydride or a mixture of maleic acid and maleic anhydride. However, in particular, this compound is maleic acid, which is formed from maleic anhydride by hydrolysis in an aqueous environment.
[0036] According to a second preferred embodiment, the at least one (meth)acrylic acid copolymer of component b) comprises, and more preferably, an alternating copolymer of at least one, preferably exactly one monomer comprising (meth)acrylic acid and a vinyl group and at least two, preferably exactly two, sulfonic acid groups.
[0037] The monomers containing a vinyl group and at least two sulfonic acid groups are preferably selected from the group consisting of vinyl disulfonic acid.
[0038] The component b) preferably comprises, and more preferably comprises, at least one (meth)acrylic acid copolymer having a mass-average molar mass calculated as poly(acrylic acid-alt-maleic acid) in the range of 55,000 to 90,000 g / mol, particularly preferably 60,000 to 80,000 g / mol, and most preferably 65,000 to 75,000 g / mol.
[0039] "Calculated as poly(acrylic acid-alt-maleic acid)" should therefore be understood as follows: Even if at least one (meth)acrylic acid copolymer of component b) is not "poly(acrylic acid-alt-maleic acid)" or is not exclusively "poly(acrylic acid-alt-maleic acid)", it is assumed that for the purpose of calculating the concentration, at least half (50%) of the monomer units of at least one (meth)acrylic acid copolymer of component b) is maleic acid.
[0040] The at least one (meth)acrylic acid copolymer of component b) is particularly preferably at least one, preferably alternating copolymer, which is a copolymer of (meth)acrylic acid and at least one, preferably exactly one, monomer (having a vinyl group and at least two, preferably exactly two carboxylic acid groups), and which, when calculated as poly(acrylic acid-alt-maleic acid), includes and more preferably has a mass-average molar mass in the range of 55,000 to 90,000 g / mol, particularly preferably in the range of 60,000 to 80,000 g / mol, and very particularly in the range of 65,000 to 75,000 g / mol.
[0041] At least one (meth)acrylic acid copolymer of component b) is added to the detergent concentrate, preferably as a salt, more preferably as an alkali metal salt, and particularly preferably as a sodium salt. A sodium salt is particularly advantageous due to the alkalinity of the resulting detergent concentrate.
[0042] A particularly suitable example is poly(acrylic acid-alt-maleic acid) (Sokalan® CP 5, BASF SE, from Germany) with a mass-average molar mass of approximately 70,000 g / mol.
[0043] Particularly suitable, correspondingly, as a polymer mixture of components a) and b) of the present invention, is a combination of polyacrylic acid (available from Sokalan® PA 30CL, BASF SE, Germany) with a mass-average molar mass of about 8000 g / mol and poly(acrylic acid-alt-maleic acid) (available from Sokalan® CP 5, BASF SE, Germany) with a mass-average molar mass of about 70000 g / mol.
[0044] The at least one (meth)acrylic acid homopolymer of component a) is preferably present in a concentration of at least 1.0% by mass, particularly preferably at least 1.5% by mass, and very preferably at least 1.7% by mass, calculated as polyacrylic acid and based on the total detergent concentrate, but preferably in an amount of up to 2.5% by mass, more preferably at a maximum of 2.0% by mass. On the other hand, the at least one (meth)acrylic acid copolymer of component b) is present in a concentration of at least 0.5% by mass, particularly preferably at least 0.7% by mass, and very preferably at least 0.9% by mass, calculated as poly(acrylic acid-alt-maleic acid) and based on the total detergent concentrate, but preferably in an amount of up to 1.5% by mass.
[0045] Here, at least one (meth)acrylic acid homopolymer of component a) and at least one (meth)acrylic acid copolymer of component b) are present in the detergent concentrate of the present invention in a mass ratio of polyacrylic acid:poly(acrylic acid-alt-maleic acid), preferably in the range of 1.0:1 to 2.5:1, more preferably in the range of 1.3:1 to 2.0:1, particularly preferably in the range of 1.5:1 to 1.9:1, and very preferably in the range of 1.7:1 to 1.8:1.
[0046] By selecting components a) and b) within the preferred range described above, the performance of the detergent obtained from the detergent concentrate of the present invention, and the effective cleaning performance combined with a harmonized pickling attack, may reach or exceed the performance of a standard phosphate-containing detergent.
[0047] The detergent concentrate of the present invention is preferably phosphate-free, which by definition means that no phosphate is added thereto during manufacturing. However, although undesirable, the raw materials used may contain trace amounts of phosphate impurities, and therefore the detergent concentrate may also contain small amounts of phosphate. In a further preferred embodiment, however, the detergent concentrate contains less than 100 ppm, more preferably less than 10 ppm, particularly preferably less than 1 ppm, and especially very preferably less than 0.1 ppm of phosphate.
[0048] The detergent concentrate is preferably silicate-free, meaning that no silicate is added to it during manufacturing. However, if the raw materials used contain trace amounts of silicate impurities, the detergent concentrate may also contain small amounts of silicate compounds. In a further preferred embodiment, however, the detergent concentrate contains less than 100 ppm, more preferably less than 10 ppm, particularly preferably less than 1 ppm, and especially very preferably less than 0.1 ppm of silicate compounds.
[0049] The reason for this is that silicate compounds, as has already been observed as described above, tend to precipitate at pH levels below 11 and therefore lose their activity as pickling inhibitors. Furthermore, they may form a crust in the washing bath or produce dry precipitates that are visually undesirable on the metal surface being treated.
[0050] The detergent concentrate of the present invention preferably further comprises at least one water-soluble boron compound c), the water-soluble boron compound c) is preferably selected from the group consisting of boric acid and alkali metal borates, and more preferably selected from the group consisting of boric acid, sodium borate, and potassium borate.
[0051] Remarkably, this allows for precise control of the aggressiveness, i.e., the pickling attack of the medium, on any metallic surface being cleaned, even on highly sensitive materials such as aluminum and galvanized and / or pre-phosphated steel. This, therefore, results in improved multi-metal performance, i.e., improved multi-metal treatment, of the cleaning agent obtained from the cleaning agent concentrate of the present invention, where different metallic surfaces, such as steel, aluminum, galvanized steel, and pre-phosphated steel, are cleaned simultaneously or successively in the same bath.
[0052] Here, galvanized steel may specifically refer to hot-dip galvanized or electro-galvanized steel, or steel coated with a zinc-magnesium alloy. The galvanized steel may also be pre-phosphated. "Aluminum" is always intended to include aluminum alloys.
[0053] At least one water-soluble boron compound c) is preferably present in a concentration of at least 7.5% by mass, more preferably at least 10.0% by mass, more preferably at least 10.5% by mass, particularly preferably at least 12.5% by mass, and very preferably at least 14.0% by mass, calculated as boric acid and based on the total concentration of the detergent concentrate, but preferably at a maximum of 25.0% by mass, more preferably at a maximum of 20.0% by mass, particularly preferably at a maximum of 17.0% by mass, and very preferably at a maximum of 16.0% by mass. By maintaining the concentration of at least one water-soluble boron compound c) within the above-mentioned lower limits, the multimetallic capacity of the detergent can be further improved, particularly in the case of a 1:50 dilution of the concentrate, while the upper limit is determined by the pH-dependent solubility of the water-soluble boron compound.
[0054] The detergent concentrate of the present invention is alkaline, meaning that the detergent concentrate has a pH greater than 7. The pH is preferably in the range of 9.5 to 14.0, particularly preferably in the range of 10.5 to 14.0, and most preferably in the range of 11.5 to 14.0. The alkalinity may be adjusted, for example, by adding corresponding amounts of sodium hydroxide or potassium hydroxide, and / or sodium carbonate or potassium carbonate, to the detergent composition of the present invention.
[0055] The detergent concentrate preferably further contains at least one salt, which, together with the conjugate acid formed in situ, forms a buffer system and acts against the decrease in pH caused by the intake of carbon dioxide from the surrounding air, thereby ensuring a stable pH of the concentrate and the detergent obtained therefrom. In this case, the at least one salt is preferably sodium carbonate, sodium bicarbonate, potassium carbonate, and / or potassium bicarbonate. The advantage of particularly favoring the use of sodium carbonate and / or potassium carbonate is that the required alkalinity can thus be established simultaneously.
[0056] Here, at least one salt is present, calculated as potassium carbonate and based on the total concentration of the detergent, preferably at least 5% by mass, more preferably at least 7% by mass, and particularly preferably 8-12% by mass.
[0057] The cleaning agent composition preferably further comprises at least one complexing agent capable of complexing interfering external ions, particularly Ca, Mg, and Zn cations, thereby retaining them in the solution and preventing them from having an adverse effect throughout operation, i.e., preventing them from contaminating the bath in the form of a film, thereby increasing the need for cleaning, and preventing them from degrading the performance of the system by reacting with the components of the cleaning agent. The at least one complexing agent preferably comprises a gluconate, which is added to the cleaning agent composition preferably in the form of sodium gluconate and / or potassium gluconate.
[0058] Here, the at least one complexing agent is preferably present in the concentrate in an amount ranging from at least 1.0% by mass, more preferably at least 2.0% by mass, and particularly preferably 2.5 to 3.5% by mass, calculated as sodium gluconate and based on the total amount of the detergent concentrate.
[0059] In a particularly preferred embodiment, the detergent concentrate of the present invention comprises the following components: a) At least 1.0% by mass of (meth)acrylic acid homopolymer, calculated as polyacrylic acid, with a mass-average molar mass in the range of 3000 to 19000 g / mol. b) A copolymer of (meth)acrylic acid and at least one vinyl dicarboxylic acid, calculated as poly(acrylic acid-alt-maleic acid), with a mass-average molar mass in the range of 50,000 to 100,000 g / mol, comprising at least 0.5% by mass. c) Calculated as boric acid, at least 10.0% by mass of sodium borate and / or potassium borate, d) At least 8.0% by mass of sodium hydroxide and / or potassium hydroxide, calculated as potassium hydroxide. e) Calculated as potassium carbonate, at least 5% by mass of sodium carbonate and / or potassium carbonate, f) A complexing agent calculated as sodium gluconate, at least 1.5% by mass, and g) at least 50% by mass of water, This includes, where (meth)acrylic acid homopolymer and copolymer of (meth)acrylic acid and at least one vinyl dicarboxylic acid are present in a mass ratio of 2.0:1 to 1.5:1, and in each case the above mass % totals 100% by mass.
[0060] The present invention further relates to a water-based alkaline cleaning agent for metallic surfaces, wherein the alkaline cleaning agent is a) At least one (meth)acrylic acid homopolymer having a mass-average molar mass in the range of 3000 to 19000 g / mol, b) At least one (meth)acrylic acid copolymer having a mass-average molar mass in the range of 50,000 to 100,000 g / mol, and h) at least one surfactant, Includes, The (meth)acrylic acid copolymer comprises at least one copolymer of (meth)acrylic acid and at least one monomer having at least two acidic groups selected from the group consisting of a vinyl group and a carboxylic acid group and a sulfonic acid group, and when the cleaning agent is a fresh cleaner, component a) is present at a maximum concentration of 0.65 g / l, preferably 0.10 to 0.50 g / l, calculated as polyacrylic acid, and component b) is present at a maximum concentration of 0.35 g / l, preferably in the range of 0.05 to 0.30 g / l, calculated as poly(acrylic acid-alt-maleic acid).
[0061] If the concentration of components a) and b) exceeds the specified maximum concentration, the cleaning performance will be sufficient, but the pickling attack will become too severe.
[0062] "Fresh cleaner" is understood here to mean a cleaner that has not yet come into contact with a metallic surface. This is because contact with a metallic surface causes ions to leach from the surface and separates oil and grease from the surface, and these ions, oil, and grease accumulate in the cleaning bath. Thus, the bath ages. As a result, the pickling attack of the cleaner is reduced, making it possible to use component a) at a concentration of 1.0 g / l or less and component b) at a concentration of 0.55 g / l or less, and still prevent pickling corrosion.
[0063] The detergent of the present invention is derived from the detergent concentrate of the present invention. 1) Dilution, preferably by water dilution, and preferably by a factor of 1:20 to 1:100 (corresponding to 10 to 50 g of concentrate per 1.0 L of detergent), 2) Addition of at least one surfactant, preferably a detergent, at a concentration in the range of 0.3 to 10 g / l, and 3) In some cases, it can be obtained by adjusting the pH using at least one acid or base.
[0064] Particularly preferably, in step 1), the dilution factor is 1:40 to 1:60, and especially preferably 1:45 to 1:55. Conversely, the concentration of at least one surfactant in step 2) is particularly preferably in the range of 0.4 to 5 g / l, and very preferably in the range of 0.5 to 3.5 g / l, based on the detergent.
[0065] During the cleaning operation, at least one surfactant acts to remove any organic impurities, such as mineral oil and grease, and is therefore necessarily added to the diluted concentrate. More specifically, this at least one surfactant includes at least one nonionic, anionic, and / or cationic surfactant.
[0066] Suitable nonionic surfactants in this context include, in particular: Alkylphenol alkoxylates, particularly alkylphenol ethoxylates, have a C6-C14 alkyl chain and a degree of alkoxylation of 5-30 moles per mole of phenol. - Alkyl polyglucosides having an alkyl chain length of C8 to C22, preferably C10 to C18, and 1 to 20, preferably 1 to 5, glucoside units. - Block copolymers comprising fatty acid amide alkoxylates, fatty acid alkanol amide alkoxylates, N-alkylglucamides, or ethylene oxide, propylene oxide, and / or butylene oxide, and -Alkoxylated C8-C22 alcohols, for example, fatty alcohol alkoxylates, oxoprocess alcohol alkoxylates, and Guerbet alcohol alkoxylates, where alkoxylation may be carried out using ethylene oxide, propylene oxide, butylene oxide, and / or mixtures thereof as block copolymers or random copolymers. The alcohol preferably has 8 to 18 atoms; the degree of alkoxylation is typically 2 to 50 moles, preferably 3 to 20 moles, of at least one of the above-mentioned alkylene oxides per mole of alcohol. The alkylene oxide head group may additionally include the following so-called end-capping groups as modifications: benzyl, methyl, and / or tert-butyl capping.
[0067] Depending on the application, the following anionic surfactants are particularly used: -A fatty alcohol surfactant having an alkyl chain length of 8 to 22 carbon atoms, preferably 10 to 18 carbon atoms, such as lauryl sulfate, cetyl sulfate, myristyl sulfate, palmityl sulfate, or stearyl sulfate. - Alkyl ether sulfate having an alkyl chain length of 8 to 22, preferably 10 to 18 carbon atoms, and - Linear C8-C20 alkylbenzene sulfonates, or other alkanesulfonates, and soaps, such as sodium or potassium salts of C8-C24 carboxylic acids.
[0068] The cationic surfactants used are, in particular, the following, depending on the application: -Quaternary mono- and di-(C7-C25 alkyl)dimethylammonium compounds, -Ester quaternary esterified mono-, di- and tri-canolamines esterified with C8-C22 carboxylic acids, and -C7~C25 alkylamines, N,N-dimethyl-N-(hydroxy-C7~C25 alkyl)ammonium salts and / or imidazoline fluoride.
[0069] The surfactant preferably comprises at least one nonionic surfactant, and more preferably at least one nonionic surfactant. Anionic surfactants tend to foam highly in most applications, while cationic surfactants often adhere to metallic surfaces, which can cause problems with the precipitation of the conversion coating. These disadvantages are not present in nonionic surfactants.
[0070] In diluting the detergent concentrate of the present invention, even without adjusting the pH, a suitable pH for use in easy pretreatment of multiple metal properties is already achieved (a ready-to-use pH), and therefore, the further addition of at least one additional acid or base is only necessary in specific applications.
[0071] The cleaning agent of the present invention is preferably phosphate-free, meaning that no phosphate is added thereto. Nevertheless, although undesirable, the raw materials used may contain small amounts of phosphate impurities, and therefore the cleaning agent concentrate and the cleaning agent produced therefrom may also contain small amounts of phosphate. The small amount of phosphate in the cleaning agent may be due to substances dissolved from the metal surface being cleaned, especially if these surfaces have been pre-treated with phosphate. However, more preferably, the phosphate content of the cleaning agent is less than 200 ppm, particularly preferably less than 20 ppm, and especially less than 2 ppm.
[0072] The detergent is preferably free of silicate compounds, meaning that no silicate compounds are added during manufacturing. However, the raw materials used may contain small amounts of silicate impurities, and therefore the detergent may also contain small amounts of silicate compounds. However, more preferably, the silicate compound content of the detergent is less than 100 ppm, more preferably less than 10 ppm, particularly preferably less than 1 ppm, and very preferably less than 0.1 ppm.
[0073] The detergent of the present invention preferably comprises at least one water-soluble boron compound c), which is preferably selected from the group consisting of boric acid and alkali metal borates, and more specifically from the group consisting of boric acid, sodium borate, and potassium borate.
[0074] The concentration of at least one water-soluble boron compound c) is preferably at least 0.15% by mass, more preferably at least 0.20% by mass, more preferably at least 0.21% by mass, particularly preferably at least 0.25% by mass, and very preferably at least 0.28% by mass, calculated as boric acid and based on the total concentration of the detergent concentrate, however, preferably at most 0.50% by mass, more preferably at most 0.40% by mass, particularly preferably at most 0.34% by mass, and very preferably at most 0.32% by mass. By adhering to the above-mentioned lower limit of the concentration of at least one water-soluble boron compound c), the multi-metal performance of the detergent can be further improved, while the upper limit arises from the pH-dependent solubility of the water-soluble boron compound in the concentrate, more particularly in the dilution of the detergent from a 1:50 concentrate.
[0075] Further advantageous embodiments and properties of the detergent of the present invention are described above in relation to the detergent concentrate of the present invention.
[0076] The present invention further relates to a method for corrosion-preventive treatment of a metallic surface, wherein the surface is treated with the following composition, i) At least one water-based alkaline cleaning agent for metallic surfaces, comprising: a) at least one (meth)acrylic acid homopolymer having a mass-average molar mass in the range of 3,000 to 19,000 g / mol; b) at least one (meth)acrylic acid copolymer having a mass-average molar mass in the range of 50,000 to 100,000 g / mol; and h) at least one surfactant, wherein at least one (meth)acrylic acid copolymer is selected from the group consisting of (meth)acrylic acid and vinyl groups, and carboxylic acid groups and sulfonic acid groups. The detergent comprises at least one copolymer of at least one monomer containing at least two acidic groups, and if the detergent is an unused detergent, component a) is present at a maximum concentration of 0.65 g / l, preferably 0.10 to 0.50 g / l, calculated as polyacrylic acid, and component b) is present at a maximum concentration of 0.35 g / l, preferably in the range of 0.05 to 0.30 g / l, calculated as poly(acrylic acid-alt-maleic acid), and at least one water-based alkaline detergent. ii) A first water-based rinse composition, iii) Optionally, a second water-based rinse composition, iv) Water-based acid conversion composition, v) Optionally, a third water-based rinse composition, and vi) A water-based composition comprising (meth)acrylate-based and / or epoxy-based cathode or anode electrodeposition materials and / or water-based or solvent-based wet or powder coating materials, This relates to a method that includes successive contacts.
[0077] Contacting the metallic surface with compositions i) through vi) in succession is not intended to exclude contact with at least one further, preferably water-based, composition, such as an activating composition or passivating composition, or with a further rinsing composition, before, after, or in between, as described later with respect to the phosphate treatment, or is not intended to exclude being subsequently subjected to at least one drying process, for example in a drying oven, or being given a further coating film, such as an undercoat, top coat, and clear coat (automotive paint system).
[0078] A key feature of the present invention is that, while operating without using a phosphate-containing cleaning agent composition, it nevertheless produces results in terms of corrosion control and paint adhesion that are equivalent to those obtained when using a phosphate-containing cleaning agent composition.
[0079] In step i), the metallic surface is brought into contact with at least one of the cleaning agents of the present invention, combining a harmonized pickling attack with efficient cleaning performance, thereby preparing a metallic surface optimal for any type of conversion treatment. Therefore, the acid conversion composition in step iv) may be a conversion coating for trication phosphate treatment, as well as a conversion coating for nickel-free zinc phosphate treatment, an organosilane-based thin film coating, or a conversion coating for providing a passivation composition.
[0080] The cleaning agent in step i) preferably further comprises at least one water-soluble boron compound c), which is preferably selected from the group consisting of boric acid and alkali metal borates, and more preferably from the group consisting of boric acid, sodium borate, and potassium borate. As already described above, this method allows for precise control of the aggressiveness (aggressiveness) of each metal surface to be cleaned and then coated, even if it is a sensitive material. The metallic surface therefore preferably includes at least one sensitive material selected from the group consisting of aluminum, galvanized steel, and pre-phosphated steel.
[0081] The addition of at least one water-soluble boron compound c) results in improved multiple metallic properties, as already described. Therefore, the metallic surface preferably comprises at least two metallic materials selected from the group consisting of steel, aluminum, galvanized steel and pre-phosphated steel, more preferably from the group consisting of aluminum, galvanized steel and / or pre-phosphated steel. Even more preferably, the metallic surface comprises not only aluminum but at least one galvanized and / or pre-phosphated steel, and particularly preferably aluminum and both at least one galvanized and at least one pre-phosphated steel.
[0082] According to the first preferred embodiment, the acid conversion composition in step iv) is a nickel-free phosphate treatment composition, which contains zinc ions and manganese ions, as well as phosphate ions, and does not contain nickel ions.
[0083] In nickel-free zinc phosphate treatments, and in tricationic phosphate treatments in which zinc, manganese, nickel ions, and phosphate ions are used, the metallic surface is usually additionally contacted with an aqueous surfactant before step iv), the aqueous surfactant preferably contains particles composed of zinc phosphate and / or titanium phosphate crystals. This promotes the precipitation of the phosphate crystal phase in step iv).
[0084] After the phosphate treatment in step iv), the metallic surface may be further contacted with an aqueous passivation composition. This may be particularly advantageous for surfaces that include areas containing aluminum in addition to areas containing zinc and / or iron. In this way, further improvements in corrosion control and paint adhesion to the painted surface can be achieved. The passivation composition described above preferably comprises at least one compound of titanium, zirconium, and / or hafnium, more preferably at least one fluorocomplex of the above elements, and also preferably at least one organosilane (including their hydrolysis and condensation products).
[0085] According to a second preferred embodiment, the acid conversion composition in step iv) is a composition for giving an organosilane-based thin film system, the composition comprising at least one organosilane, including hydrolysis and condensation products thereof, but optionally, at least one compound of titanium, zirconium, and / or hafnium.
[0086] Unlike phosphate treatment, the cleaning agent compositions of the present invention, when combined with an organosilane-based thin film system, provide better corrosion protection than conventional phosphate-containing cleaning agents, and this applies when the cleaning agent composition is phosphate-free. At least one cleaning agent of the present invention in step i), and therefore the cleaning agent concentrate of the present invention, is therefore preferably phosphate-free, and this applies in particular when an organosilane-based thin film system is subsequently provided.
[0087] According to a third preferred embodiment, the water-based acid conversion composition in step iv) comprises a passivation composition which, in addition to titanium, zirconium, and / or hafnium compounds, comprises at least one fluorocomplex of the elements described above, and optionally at least one more organosilane—including its hydrolysis and condensation products.
[0088] Advantageous embodiments and features of the present invention used in step i) are those described above with respect to the detergent concentrate and the detergent of the present invention.
[0089] The present invention further relates to a corrosion-resistant metallic surface that can be obtained using the method of the present invention, and to a method for using the product in the metalworking industry, particularly in the automotive, automotive parts supply sector, or general industry, where a conversion step is used for pretreatment purposes.
[0090] The present invention will be described below using examples and comparative examples, but it should be understood that the above examples are not intended to imply any limitations. [Examples]
[0091] i) Determination of pickling corrosion: Measurement principle: Pickling corrosion indicates the mass loss of the base metal during the cleaning process. This is tested by immersing a standard sheet of specified AA6014 aluminum (Gardobond® test sheet, Chemetall GmbH, Germany), measuring 105 × 190 mm, in the solution under test—in this case, the corresponding cleaning solution. The mass loss is then measured by gravimetric method using a chemical balance. The test in this case is limited to the aluminum surface, as these are the most susceptible to pickling attack.
[0092] Preparation of test sheets To remove any organic impurities, the test sheets were first pre-degreased using petroleum spirits. This allowed for a direct attack of the test solutions on the base substrates to be evaluated and compared.
[0093] Measurement of pickling corrosion The mass of each pre-degreased test sheet was measured on a chemical balance. Immediately thereafter, the test sheets were immersed for 10 minutes at 55°C in a 3L beaker containing the corresponding test solution. The beaker was stirred at a speed of 500 rpm at the bottom using a 40mm magnetic stirrer.
[0094] After 10 minutes, the test sheet was removed from the test solution, rinsed with thoroughly desalted (FD) water, and dried using compressed air. The mass loss was then measured using a chemical balance.
[0095] To make the obtained values comparable, a reference was tested in parallel in each case.
[0096] ii) Measurement of minimum washing time Measurement principle: The Minimum Cleaning Time (MCT) indicates the minimum duration of the cleaning process required to remove organic impurities from a standard sheet (test sheet) of 1.0312 steel with dimensions of 105 × 190 mm under specific conditions. The cleaning quality must achieve a specified minimum value, which was determined based on the percentage of water wetting of the metal surface. This was performed exclusively on the steel surface because it is typically the most difficult surface to degrease.
[0097] Creating an exam sheet The test sheet used had a constant oil coating (1.7 + / - 0.2 g / m²). 2 ) was present. This was helpful in comparing the results.
[0098] Measurement of minimum washing time: To measure the minimum washing time, each test sheet was immersed in a 3L beaker containing the corresponding detergent solution at 55°C for 1 minute. The bottom of the beaker was stirred at a speed of 500 rpm using a 40mm magnetic stirrer. The test sheets were then rinsed in an immersive rinse with a back-and-forth motion (approximately 15 back-and-forth movements). In each case, the sheet was always completely removed from the rinse water and held vertically (to exclude apparent wetting) for evaluation after 10 seconds. The minimum cleaning time was achieved when the surface was at least 95% wet, i.e., when a tightly adhering water film was present. If this condition was not met, the test sheet was immersed in the cleaning solution for an additional minute as described above, and then rinsed in the immersion rinse. This was repeated until the condition was met.
[0099] To total the number of repetitions and for verification, test sheets of the same oil were left in the cleaning solution for the entire duration. This was necessary because an intermediate rinsing step improves cleaning performance. If the sheet was at least 95% wet after the total time, this time was recorded as the Maximum Clutch Time (MCT). If this was not the case, the washing and rinsing cycle was repeated in 1-minute increments without an intermediate rinsing step until the surface was at least 95% wettable. This time was then recorded as the MCT. iii) Investigation of different cleaning solutions: To test the effects of pickling corrosion and MCT on different polymers, a standard detergent concentrate (VB1) with a pH of 12.9 was initially prepared as a reference, containing FV water and the following components: [Table 1]
[0100] By adding the following polymers to this standard, different detergent concentrates were obtained (VB2-VB6 and B1).
[0101] [Table 2]
[0102] Furthermore, a standard concentrate (VB7) containing phosphate with a pH exceeding 11.5 was prepared as a reference, which contained FV water and the following components: [Table 3]
[0103] All detergent concentrates were then diluted with FV water at a factor of 1:50 (corresponding to 20 g of concentrate per 1.0 L of detergent) and mixed with 2 g / l of ethylene / propylene oxide fatty alcohol, i.e., a nonionic surfactant.
[0104] Additionally, the pH of all detergent concentrates was adjusted to 10.5 by adding boric acid or potassium hydroxide aqueous solution.
[0105] Next, the resulting cleaning solution was tested for pickling corrosion and MCT as described above (Notes i) and ii). The results are shown in Table 1 (in each case, the average value of at least three sheets, i.e., n≧3).
[0106] [Table 4]
[0107] The experimental results indicate that significant improvements in cleaning performance can be achieved by adding polymer-polyacrylic acid or poly(acrylic acid-alt-maleic acid) (see MCT; VB2-VB6 and B1 vs VB1). At the same time, the aggressiveness of the medium towards aluminum increased (see pickling corrosion). In the case of polyacrylic acid, it is clear that the effect of polymer addition increased in terms of pickling attack and MCT as the chain length increased, i.e., as the molar mass increased (VB2-VB4).
[0108] Furthermore, it was found that the polymers alone could not achieve the same performance against pickling corrosion and MCT as standard phosphate-containing cleaning agents. Only the cleaning solution (B1) of the present invention, containing a specific mixture of the two polymers, achieved a generally low input concentration and harmonized pickling attack of 0.8 g / m². 2 In the following cases of pickling corrosion, it is possible to achieve or even surpass the cleaning performance of a phosphate-containing cleaning agent (VB7)—MCT of less than 4 minutes. However, when the concentrations of the two polymers are doubled (increased), the cleaning performance remains satisfactory, but the pickling attack becomes too severe (VB6).
[0109] iv) Measurement of properties of multiple metals: Using the two measurement principles described above, pickling corrosion (Table 2: n≧3, see reference) and MCT (Table 3: n≧3, see reference), but using a specific VDA230-213 test apparatus in each case, the multiple metal properties of various solutions were similarly measured. These tests were performed on the following four substrates used in the automotive industry: cold-rolled steel (CRS), hot-dip galvanized steel (HDG), pre-phosphated steel (ZEP), and automotive-grade aluminum (AA6014).
[0110] [Table 5]
[0111] [Table 6]
[0112] As can be clearly seen from Table 2, in the case of the cleaning agent solution (B1) of the present invention, the pickling attack is actually somewhat higher compared to the phosphate-containing cleaning agent (VB7). However, in contrast to cleaning agent solutions based on only one polymer, the values obtained for aluminum (AA6014) at lower polymer concentrations (VB8) are also acceptable for current operations and thus support the multi-metal performance of the cleaning agent solution of the present invention.
[0113] Table 3 shows that the minimum cleaning time (MCT), i.e., cleaning performance, of the cleaning agent solution (B1) of the present invention is better in each case, particularly with substrates used in multiple metal operations, compared to the phosphate-containing cleaning agent (VB7), but also better than the cleaning agent solution (VB8) based on only one polymer with a lower polymer concentration. The results obtained for pickling corrosion and MCT using a specific VDA230-213 test apparatus were higher than those obtained by manual verification in Table 1, which is due to lower circulation / bath activity within the apparatus.
[0114] To determine the optimal state in terms of pickling attack in multiple metal operations, the concentration of borate in the cleaning agent solution B1 of the present invention was further varied. The cleaning solutions thus prepared (B1-1 to B1-3) were then tested as described above (Note i)) for pickling corrosion on the following three substrates used in the automotive industry: automotive-grade aluminum (AA6014), hot-dip galvanized steel (HDG), and electro-galvanized steel (MBZE). The metal sheets used for this purpose were each pre-degreased using a surfactant solution.
[0115] The results obtained are shown in Table 4 (average value of at least 3 sheets, i.e., n≧3).
[0116] [Table 7]
[0117] As can be seen from the experimental results of the detergent solution B1 and its variations B1-1 and B1-3 of the present invention, when the concentration of boric acid in the concentrate was in the range of 14.5% and 16.5% by mass, i.e., 0.29% and 0.33% by mass, respectively, in the detergent solution at a 1:50 dilution, the pickling attack of aluminum (AA6014) was within the desired low range. Thus, all substrates containing aluminum that were tested could be combined and treated optimally.
[0118] v) Compatibility with conversion processing: The compatibility of the cleaning agent solution (B1) of the present invention with known conversion treatments was tested based on a thin film coating of organosilane and / or trication phosphate treatment. To investigate the effects of the cleaning agent solution (B1) of the present invention, the corresponding polymers were added to both conversion baths (B2 and B3) in amounts greater than the usual amount for the process, so that they would travel along the components in the conversion bath and reach the cleaning agent medium. Subsequently, the following substrates used in the automotive industry—cold rolled steel (CRS), hot-dip galvanized steel (HDG), and aluminum (AA6014)—were pre-treated according to standard processing procedures, followed by pre-activation with organosilane and zirconium compounds, or zinc-manganese-nickel phosphate (phosphate treatment: 180 seconds), or zinc phosphate (activation time: 60 seconds).
[0119] The effect of the polymer was evaluated by measuring the coating mass (CW) of the obtained conversion coats using X-ray fluorescence (XRF) analysis and scanning electron microscopy (SEM) imaging. The measured coating masses—calculated as zirconium metal (Zr)—for organosilane-based thin film coatings are shown in Table 5 (n≧3).
[0120] [Table 8]
[0121] The deviations occurring within the different modifications (VB9, B2, and B3) were within the acceptable error range for CW measurements. SEM images of the surface structure of the conversion films showed no abnormalities in any case. The polymers used in this invention therefore do not adversely affect the optimal development of organosilane-based thin film coatings and are thus compatible with the aforementioned systems. The measured film mass was calculated as Zn3(PO4)2·4H2O and is shown in Tables 6 and 7, respectively, for zinc phosphate and for the following tricationic phosphate treatment (n≧3 in each case).
[0122] [Table 9]
[0123] [Table 10]
[0124] The obtained film masses indicate that the two polymers did not affect the activation of zinc phosphate (Note, Table 6) and showed only a slight effect on trication phosphate treatment (Note, Table 7) (B4 and B5 vs. VB10), and these effects can be compensated for within the current procedure by adjusting the phosphate parameters. SEM images of the surface structure of the trication conversion film showed no abnormalities.
[0125] Therefore, it was possible to demonstrate not only the compatibility of the cleaning agent solution of the present invention with organosilane-based thin film coatings, but also its compatibility with trication phosphate treatment systems.
[0126] vi) Corrosion behavior within thin film coatings of organosilane bases: To investigate the effect of the cleaning agent solution B1 of the present invention on the corrosion behavior, a sheet-like material HDG was treated using a standardized process. Process: 1.) Spray clean for 60 seconds 2.) Immerse and wash for 180 seconds 3.) Soak and rinse for 30 seconds 4.) Immersion conversion, 180 seconds 5.) Soak and rinse for 30 seconds 6.) Drying using compressed air
[0127] The phosphate-free detergent solution of the present invention was used in a 1:50 dilution from the concentrate and in 2 g / l ethylene / propylene oxide fatty alcohol to perform washing steps 1) and 2). For comparison, two standard phosphate-containing detergents (VB11 and VB12) were also tested.
[0128] For the conversion in step 4), a thin organosilane-based film system (Chemetall, Germany) was used. After step 6, the treated sheets were tested for paint adhesion and corrosion, using the standard cyclic corrosion test (VDA621-415) used in the automotive sector.
[0129] Table 8 shows the results of paint adhesion after corrosive undermining and stone chipping (n≧3 in each case).
[0130] It is clear that the phosphate-free cleaning agent solution B1 of the present invention, when combined with an organosilane-based conversion system, significantly improves both corrosion behavior and surface paint adhesion characteristics compared to standard phosphate-containing cleaning agents (VB11 and VB12).
[0131] [Table 11]
Claims
1. A water-based alkaline cleaning agent concentrate for manufacturing cleaning agents for metallic surfaces, a) At least one (meth)acrylic acid homopolymer having a mass-average molar mass in the range of 5,000 to 19,000 g / mol, and b) At least one (meth)acrylic acid copolymer having a mass-average molar mass in the range of 50,000 to 100,000 g / mol, A detergent concentrate comprising, wherein at least one (meth)acrylic acid copolymer comprises at least one linear copolymer of (meth)acrylic acid and at least one monomer having at least two acidic groups selected from the group consisting of a vinyl group and a carboxylic acid group and a sulfonic acid group, and wherein the amount of silicate compound in the alkaline detergent concentrate is less than 100 ppm.
2. The detergent concentrate according to claim 1, characterized in that at least one (meth)acrylic acid homopolymer of component a) comprises at least one (meth)acrylic acid homopolymer having a mass-average molar mass in the range of 5,000 to 15,000 g / mol when calculated as polyacrylic acid.
3. The detergent concentrate according to claim 1 or 2, characterized in that at least one (meth)acrylic acid copolymer of component b) comprises at least one copolymer of (meth)acrylic acid and at least one comonomer comprising a vinyl group and at least two carboxylic acid groups.
4. The detergent concentrate according to any one of claims 1 to 3, characterized in that component b) contains at least one (meth)acrylic acid copolymer having a mass-average molar mass in the range of 55,000 to 90,000 g / mol, calculated as poly(acrylic acid-alt-maleic acid).
5. A detergent concentrate according to any one of claims 1 to 4, characterized in that at least one (meth)acrylic acid homopolymer of component a) is present at a concentration of at least 1.0% by mass when calculated as polyacrylic acid, and at least one (meth)acrylic acid copolymer of component b) is present at a concentration of at least 0.5% by mass when calculated as poly(acrylic acid-alt-maleic acid).
6. The detergent concentrate according to any one of claims 1 to 5, characterized in that at least one (meth)acrylic acid homopolymer of component a) and at least one (meth)acrylic acid copolymer of component b) are present in a ratio of 1.0:1 to 2.5:1 when calculated as polyacrylic acid:poly(acrylic acid-alt-maleic acid).
7. A detergent concentrate according to any one of claims 1 to 6, characterized in that it does not contain phosphate.
8. A detergent concentrate according to any one of claims 1 to 7, further comprising at least one water-soluble boron compound c).
9. The detergent concentrate according to claim 8, characterized in that at least one water-soluble boron compound c) is present in an amount of at least 10.5% by mass, calculated as boric acid.
10. A water-based alkaline cleaning agent for metallic surfaces, The alkaline cleaning agent is a diluted product of the cleaning agent concentrate described in any one of claims 1 to 9. The alkaline cleaning agent contains h) at least one nonionic surfactant, A water-based alkaline cleaning agent characterized in that, when the cleaning agent is an unused cleaning agent, component a) is present at a maximum concentration of 0.65 g / l calculated as polyacrylic acid, and component b) is present at a maximum concentration of 0.35 g / l calculated as poly(acrylic acid-alt-maleic acid).
11. A method for corrosion-preventive treatment of a metallic surface, wherein the surface is treated with the following composition, i) At least one water-based alkaline cleaning agent according to claim 10, ii) First water-based rinse composition, iii) Optionally, a second water-based rinse composition, iv) Water-based acid conversion composition, v) Optionally, a third water-based rinse composition, and vi) A water-based composition comprising (meth)acrylate-based and / or epoxy-based cathode or anode electrodeposition materials and / or water-based or solvent-based wet or powder coating materials, A method that includes successive contacts.
12. The method according to claim 11, wherein the acid conversion composition in step iv) includes a nickel-free zinc phosphate treatment composition, the nickel-free zinc phosphate treatment composition includes phosphate ions in addition to zinc ions and manganese ions, and no nickel ions are added to the nickel-free zinc phosphate treatment composition.
13. The method according to claim 11, wherein the acid conversion composition in step iv) comprises a composition for applying an organosilane-based thin film system, the composition comprising at least one organosilane, its hydrolysis and condensation products, and optionally further comprising at least one titanium compound, a zirconium compound, and / or a hafnium compound.