Use of alkoxylated fatty alcohols for improving the low-temperature cleaning of metal components

Abstract

The invention relates to an alkaline aqueous cleaner with a pH above 8.5, containing, in each case based on the cleaner, at least 0.10 wt. % of a surfactant mixture comprising (i) at least 50 wt. %, based on the total amount of components (i) to (iii), of one or more surfactants selected from fatty alcohols alkoxylated with ethylene oxide (EO) and propylene oxide (PO), which have an EO:PO ratio of greater than 1:1, (ii) less than 50 wt. %, based on the total amount of components (i) to (iii), of one or more surfactants selected from fatty alcohols alkoxylated with ethylene oxide (EO) and propylene oxide (PO), which have an EO:PO ratio of 1:1 or less, and (iii) optionally further surfactants, preferably with defoaming properties; 0.10 to 5.0 wt. % of alkali metal hydroxides; 0.05 to 4.0 wt. % of water-soluble phosphates; optionally up to 1.0 wt. % of organic complexing agents and water. The invention also relates to a method for degreasing the metal surfaces of a component, in which at least the metal surfaces of the component are brought into contact with the described alkaline aqueous cleaner, wherein the temperature of the cleaner is below 50 °C when it is brought into contact with the surface.

Description

[0001] Use of alkoxylated fatty alcohols to improve the

[0002] Low-temperature cleaning of metallic components

[0003] The present invention relates to a method for low-temperature cleaning of metallic components by means of alkaline aqueous cleaners to which a specific surfactant mixture is added, as well as to the alkaline aqueous cleaner comprising said surfactant mixture.

[0004] State of the art

[0005] In highly automated industrial series production, the cleaning of semi-finished products, components, and materials plays a key role in their successful further processing into the respective final product. The key function of cleaning is to provide standardized and thus reproducible surfaces in the series production of complex components. A reproducible surface finish across all semi-finished products, components, and materials is often a prerequisite for the effectiveness and longevity of coatings, bonding, welds, and forming processes that must be carried out along the production chain to produce the final product.Any surface finish that deviates from a well-defined standard must therefore be identified early on in production and remedied by targeted intervention in the cleaning process to prevent the production of defective end products and ensure high productivity. At the same time, such high productivity demands in series production require not only high-quality cleaning steps but also cleaning processes that can be operated reliably within a wide process window in order to be able to respond flexibly to changing levels of contamination in the semi-finished products, components, and materials to be cleaned.

[0006] EP 3783450 A1 describes such a production line suitable for the serial cleaning of components, in which, in order to achieve a desired surface finish, certain control variables of a cleaning bath can be addressed depending on the degree of contamination, both in a resource-saving manner and from the point of view of the lowest possible energy consumption.

[0007] The well-known immersion cleaning processes for various substrates and types of contaminants are carried out at high temperatures, i.e., in a range of 55°C to 70°C. However, the treatment times are very long due to the minimal or nonexistent bath movement. The cleaning results achieved, however, are only adequate despite the high temperatures and long treatment times. Alkaline immersion cleaning is hardly practical at low temperatures, i.e., below 50°C.

[0008] It is of great economic and ecological importance that the energy consumption for cleaning, and thus essentially the process temperature, can be reduced as much as possible. Cleaning metallic semi-finished products contaminated with corrosion protection, drawing, and forming oils typically requires the use of alkaline cleaners, which are used by spraying and / or immersion at temperatures often reaching 50 °C and above.

[0009] The present invention now sets itself the task of providing an alkaline aqueous cleaner and a cleaning method for the series production of components that are at least partially made of metallic materials, in which complete degreasing can be reliably achieved even at bath temperatures below 50 °C ("low-temperature degreasing"). In particular, the cleaner and the method should be suitable for significantly improving the degreasing performance of alkaline aqueous cleaners with regard to metallic surfaces of zinc, iron and / or aluminum in order to be able to vary the working window with regard to the process temperature in the serial cleaning of these materials over a wide range in accordance with requirements, i.e. the stability of the cleaner must be ensured.

[0010] Brief description of the invention

[0011] Surprisingly, it has now been discovered that by adding a surfactant based on the fatty alcohol 2-ethylhexanol to conventional metal cleaning systems, completely oil- and grease-free metal surfaces can be achieved, even at low to moderate application temperatures, but otherwise under standard cleaning conditions in terms of cleaning time, bath circulation, and spray pressure. The newly developed surfactant improves the cleaning performance of cleaning processes in the low-temperature range and can also significantly shorten cleaning times.

[0012] The present invention therefore initially relates specifically to an alkaline aqueous cleaner having a pH value above 8.5, which in each case, based on the cleaner, contains a) at least 0.10 wt.%, preferably at least 0.20 wt.%, particularly preferably at least 0.25 wt.% of a surfactant mixture comprising

[0013] (i) at least 50% by weight, preferably at least 65% by weight, particularly preferably at least 80% by weight, in each case based on the total amount of components (i) to (iii), of one or more surfactants selected from fatty alcohols alkoxylated with ethylene oxide (EO) and propylene oxide (PO), which have an EO:PO ratio of greater than 1:1; (ii) less than 50% by weight, preferably less than 30% by weight, particularly preferably less than 20% by weight, but preferably at least 5% by weight, in each case based on the total amount of components (i) to (iii), of one or more surfactants selected from fatty alcohols alkoxylated with ethylene oxide (EO) and propylene oxide (PO), which have an EO:PO ratio of 1:1 or less;

[0014] (iii) optionally further surfactants, preferably with defoaming properties, particularly preferably selected from fatty amine alkoxylates and / or fatty alcohol alkoxylates, b) 0.10 to 5.0 wt.%, preferably 0.20 to 4.0 wt.%, particularly preferably 0.30 to 3.0 wt.% of alkali metal hydroxides, preferably selected from potassium hydroxide, calculated as KOH; c) 0.05 to 4.0 wt.%, preferably 0.10 to 3.0 wt.%, particularly preferably 0.20 to 2.0 wt.% of water-soluble phosphates, preferably selected from orthophosphates, pyrophosphates and / or tripolyphosphates, calculated as PO4, and / or carbonates calculated as CO3; d) optionally up to 1.0 wt.-% of organic complexing agents, preferably selected from a-hydroxycarboxylic acids, preferably selected from lactic acid, glycolic acid and / or gluconic acid and their water-soluble salts, di- and / or tricarboxylic acids, preferably selected from tartaric acid and / or citric acid and their water-soluble salts, and / or phosphonic acids, preferably selected from aminotrimethylenephosphonic acid and / or etidronic acid and their water-soluble salts, and e) water.

[0015] In a further aspect, the present invention relates to a method for degreasing the metallic surfaces of a component, in which at least the metallic surfaces of the component are brought into contact with an alkaline aqueous cleaner, wherein the temperature of the cleaner during contact is below 50 °C, and the cleaner comprises a surfactant mixture containing the components (i)-(iii):

[0016] (i) at least one or more surfactants selected from fatty alcohols alkoxylated with ethylene oxide (EO) and propylene oxide (PO) having an EO:PO ratio of greater than 1:1, (ii) at least one or more surfactants selected from fatty alcohols alkoxylated with ethylene oxide (EO) and propylene oxide (PO) having an EO:PO ratio of 1:1 or less, and

[0017] (iii) optionally further surfactants, preferably with defoaming properties, wherein the surfactant mixture contains at least 50% by weight of component (i), based on the total amount of components (i) to (iii).

[0018] The claimed improvement in cleaning performance is demonstrated in each case with regard to the wettability in the water break test after degreasing using test sheets with the same degree of soiling, whereby the degreasing is carried out comparatively in the absence and presence of the selected fatty alcohol alkoxylated with ethylene oxide (EO) and propylene oxide (PO) with a ratio of EO:PO of greater than 1:1, but otherwise under the same application conditions.

[0019] Detailed description of the invention

[0020] The detailed and specific embodiments of the invention described below are for illustrative purposes only, meaning that various modifications may be made without departing from the invention. The present invention is limited only by the appended claims.

[0021] All embodiments disclosed and claimed herein may be implemented and carried out without undue experimentation in view of the disclosure.

[0022] The contents of the documents referred to herein shall be deemed to be incorporated in their entirety into this document.

[0023] The present invention is the realization of the solution to one or more of the above-mentioned problems.

[0024] According to the invention, a significant improvement in cleaning performance at low to moderate application temperatures is achieved by the surfactant mixture which comprises at least 50% by weight (based on the total amount of the components of the surfactant mixture) of at least one or more surfactants selected from fatty alcohols alkoxylated with ethylene oxide (EO) and propylene oxide (PO) and having an EO:PO ratio of greater than 1:1, and at least one or more surfactants selected from fatty alcohols alkoxylated with ethylene oxide (EO) and propylene oxide (PO) and having an EO:PO ratio of 1:1 or less. Compared to conventional alkaline aqueous cleaners which do not comprise this surfactant mixture, a significant reduction in the energy consumption of a cleaning system can be achieved.Accordingly, for optimal to still sufficient degreasing performance with simultaneous significant energy savings, it is preferred if the application temperature when used according to the invention is below 50.0 °C, particularly preferably below 45.0 °C, very particularly preferably below 40.0 °C and especially preferably below 35.0 °C.

[0025] However, in order to maintain sufficient degreasing performance with usual residence times in the cleaning zone, which can be from 30 to 600 seconds, it will regularly be necessary not to lower the application temperature below 20 °C, so that in the process according to the invention and when used according to the invention, an application temperature of at least 25.0 °C, particularly preferably of at least 30.0 °C, very particularly preferably of at least 35.0 °C is preferably realized.

[0026] The embodiments of the method according to the invention mentioned below can be readily transferred to the first aspect of the invention relating to the alkaline aqueous cleaner.

[0027] The metallic surface of a component cleaned with the alkaline-aqueous cleaner is not restricted in any way, and the surfaces can include, in particular, copper, steel, alloy-galvanized steel, and aluminum, as well as their alloys. Degreasing with alkaline-aqueous cleaners is particularly suitable for metallic surfaces of steel, galvanized and alloy-galvanized steel, especially for grades (Z), (ZF), (ZA), (AZ), (AS), and (ZM), and aluminum, preferably aluminum and its alloys. Aluminum alloys include materials that consist of at least 50 at.% aluminum.

[0028] Naturally, the improved degreasing performance at low application temperatures achieved according to the invention is independent of the type of component and is not influenced by its spatial configuration. Therefore, all components that are at least partially made of a metallic material, which in turn also forms a surface of the component accessible for cleaning with a fluid, are considered components within the meaning of the invention. Typical components that must be freed from oil and grease residues or other contaminants for further processing are semi-finished products and blanks resulting from forming and metal-cutting processes, such as sheets, profiles, rods, tubes, discs, and can cylinders, as well as joined, cast, or additively manufactured components such as car bodies, housings, tools, and machine parts.

[0029] The method of bringing the alkaline-aqueous cleaner into contact with the metallic surfaces of the component is also not limited in any way and can be carried out using conventional methods known in the prior art, preferably by immersion with or without ultrasound and / or by spraying. Application takes place in a zone in which the alkaline-aqueous cleaner is applied from one or more storage containers for application and / or is kept in one or more system tanks, preferably only one system tank for energy reasons, for contacting. A system tank is therefore a container in which the alkaline-aqueous cleaner is located for cleaning purposes, but is not necessarily the location of contact.Thus, a sufficient portion of the treatment solution stored in a system tank to bring the surfaces of the component into contact can be drawn from the system tank and applied to the component spatially separated from the system tank, for example, in a spray or fogging chamber. However, the method is particularly advantageous for cleaning zones in which the cleaner is applied by immersing the components in a system tank containing the cleaner, since the greatest energy savings can be achieved in such systems using a method according to the invention.

[0030] It has been found that in the alkaline aqueous cleaner, in particular the alkoxylated fatty alcohols mentioned are suitable for developing a good degreasing performance in the process according to the invention, even at low application temperatures.

[0031] Fatty alcohol alkoxylates (alkoxylated fatty alcohols) within the meaning of the present invention are compounds which comprise at least one hydrophobic residue (fatty alcohol) and at least one hydrophilic residue (alkoxylated with ethylene oxide and propylene oxide). The alkoxylated fatty alcohols according to the present invention are compounds which comprise at least one hydrophobic residue and at least one hydrophilic residue.

[0032] The alkoxylated fatty alcohols according to the present invention may have a weight-average molecular mass of less than 2000 g / mol, preferably less than 1500 g / mol, particularly preferably less than 900 g / mol and most preferably less than 700 g / mol.

[0033] The hydrophilic radical can have up to 30 units of ethylene oxide (EO) and propylene oxide (PO), preferably up to 20 units of ethylene oxide (EO) and propylene oxide (PO), particularly preferably up to 15 units of ethylene oxide (EO) and propylene oxide (PO), and very particularly preferably up to 10 units of ethylene oxide (EO) and propylene oxide (PO), for example 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 ethylene oxide (EO) and propylene oxide (PO). This is the sum of ethylene oxide (EO) and propylene oxide (PO) units, i.e. if 30 units are bound to a fatty alcohol, the 30 units can each be ethylene oxide (EO) and propylene oxide (PO).

[0034] The hydrophilic residue of the alkoxylated fatty alcohol can be a random copolymer or a block copolymer. Random copolymers are a type of copolymer in which two or more monomers are randomly distributed along the polymer chain and follow statistical rules. In these copolymers, the sequence of monomer residues follows statistical principles. If the probability of finding a particular monomer residue at any point in the chain is equal to the mole fraction, the polymer is considered a truly random copolymer. These copolymers are influenced by the reaction kinetics of the chemically distinct monomer reactants and are commonly referred to as "random" or "random" in the polymer literature. Block copolymers are a special class of copolymers in which chemically distinct monomer units are grouped in discrete blocks along the polymer chain.These polymers consist of molecules with a linear arrangement of blocks, where a block is defined as a part of a polymer.

[0035] The hydrophobic residue is a fatty alcohol, i.e. the hydrophobic residue is derived in particular from aliphatic, long-chain, monohydric alcohols.

[0036] Even-numbered fatty alcohols are preferred due to their better biodegradability. The fatty alcohol can be a C12 to C22 fatty alcohol, preferably a C13 to C18 fatty alcohol, particularly preferably a C12 to C12 fatty alcohol, and especially preferably a C8 to C10 fatty alcohol. The fatty alcohol can be a C8 fatty alcohol.

[0037] The fatty alcohol can be branched or linear, with the hydrophobic residue preferably being branched.

[0038] The fatty alcohol can be saturated, monounsaturated or polyunsaturated, with fully saturated residues being preferred.

[0039] The fatty alcohol can be selected from the group consisting of 1-hexanol, 1-heptanol, 1-octanol, 1-decanol, 1-dodecanol, 1-tetradecanol, 1-hexadecanol, 1-heptadecanol, 1-octadecanol, 1-eicosanol, 1-docosanol and combinations thereof.

[0040] The fatty alcohol can be selected from the group consisting of cis-9-hexadecen-l-ol, cis-9-octadecen-l-ol, trans-9-octadecen-l-ol, cis-11-octadecen-l-ol and combinations thereof.

[0041] The fatty alcohol can be cis,cis-9,12-octadecadien-l-ol and / or 6,9,12-octadecatrien-l-ol.

[0042] The fatty alcohol can be a primary branched aliphatic alcohol having more than 6 carbon atoms. Preferably, the primary branched aliphatic alcohol has more than 6 and fewer than 10 carbon atoms. More preferably, the primary branched aliphatic alcohol has more than 6 and fewer than 10 carbon atoms, with at least 5 carbon atoms in the aliphatic main chain.

[0043] The fatty alcohol can be 2-propyl-1-pentanol and / or 2-ethyl-1-hexanol. The fatty alcohol is preferably 2-ethyl-1-hexanol. The cleaner can comprise, based on the total weight of components (i) to (iii), at least 65% by weight, preferably 80% by weight, of component (i); and / or less than 30% by weight, preferably 5 to 20% by weight, of component (ii). It is particularly preferred if the cleaner comprises, based on the total weight of components (i) to (iii), at least 80% by weight of component (i) and 10% by weight of component (ii). Components (i) and (ii) can comprise a plurality of surfactants; for example, components (i) and (ii) can comprise 2, 3, 4, 5, 6, or more surfactants.

[0044] Overall, it is advantageous for a reliable increase in degreasing performance at low to moderate application temperatures if the total proportion of components (i) and (ii) contained in the alkaline aqueous cleaner is at least 0.10 g / kg, particularly preferably at least 0.50 g / kg, but preferably less than 10.0 g / kg, particularly preferably less than 5.0 g / kg, in each case based on the cleaner.

[0045] For the suitability of the cleaner for degreasing, i.e. the removal of corrosion inhibitors, drawing and forming oils from metallic surfaces, it is essential that the aqueous cleaner in the process according to the invention is alkaline and preferably has a pH value above 8.5, preferably above 9.0, but preferably below 11.0, particularly preferably below 10.0. According to the invention, the pH value corresponds to the negative decimal logarithm of the hydronium ion activity measured in the cleaner at a temperature of 25 °C using a pH-sensitive glass electrode after two-point calibration against technical buffer solutions of acetic acid / acetate and boric acid / borate.

[0046] Preferably, the alkaline aqueous cleaner is provided with a specific buffer capacity so that in the process according to the invention it has a total alkalinity in points of at least 4.0, particularly preferably of at least 6.0, most preferably of at least 7.0, but preferably a total alkalinity of 11.0 is not exceeded. The total alkalinity corresponds to the consumption of 0.1 N hydrochloric acid in milliliters after titration of a solution of 50 ml of deionized water (K ​​< 1 pScm- x ) diluted sample volume of 10 ml of the cleaner in the presence of the indicator bromocresol green (transition point: pH 3.6) at a temperature of 25 °C.

[0047] To adjust the alkalinity of the aqueous cleaner, any builders known in the art that represent alkaline-reacting compounds or a mixture of such compounds can be used. Particularly suitable and established builders are alkaline-reacting inorganic compounds, which are preferred in the context of the present invention and are particularly preferably selected from water-soluble hydroxides, carbonates, borates, silicates, and / or phosphates, wherein in turn, at least water-soluble carbonates and / or phosphates are preferably present, which in turn are preferably selected from orthophosphates, pyrophosphates, and / or tripolyphosphates.Suitable builders are therefore alkali metal carbonates, preferably selected from potassium carbonate, mixtures of alkali metal hydroxides, preferably selected from potassium hydroxide, with phosphoric acid and / or with boric acid and alkali metal tripolyphosphates, preferably selected from potassium tripolyphosphate.

[0048] A beneficial factor for good degreasing performance is the presence of surface-active substances. These substances are not formed as anionic fatty acids in the system tank through saponification of the oils adhering to the components, but are already formulated into the cleaner to impart a more extensive emulsifying effect. In principle, all surface-active substances known in the art that are capable of emulsifying non-polar components in a continuous aqueous phase are suitable. These include anionic surfactants, but especially non-ionic surfactants (nonionic surfactants).

[0049] In a preferred embodiment of the process according to the invention, the alkaline aqueous cleaner therefore contains at least one further nonionic surfactant which differs from the surfactants according to components (i) and (ii) and has an HLB value above 10.0, preferably above 11.0, particularly preferably above 12.0. In the context of the present invention, the HLB value is an empirical value and is calculated as follows: HLB = 20 ■ (1 - ML / M), where "ML" corresponds to the molar mass of the lypophilic group of the nonionic surfactant and "M" to the molar mass of the nonionic surfactant. Fatty amine alkoxylates and / or fatty alcohol alkoxylates have proven to be particularly suitable for degreasing, so that this type of nonionic surfactant is preferred according to the invention.

[0050] Said additional non-ionic surfactant can be selected from fatty amine alkoxylates having at least 8 but fewer than 14 EO units, which in turn are preferably selected from fatty amine ethoxylates having at least 10 but no more than 16 carbon atoms in the aliphatic (hydrophobic) radical. 12-fold ethoxylated coconut amine is most preferably present in the alkaline cleaner.

[0051] As a further nonionic surfactant which is also particularly suitable with regard to degreasing, at least one fatty alcohol alkoxylate which has at least 6 but fewer than 10 EO units is preferably present in the alkaline aqueous cleaner of the process according to the invention, which fatty alcohol alkoxylate in turn is preferably selected from fatty alcohol ethoxylates having at least 10 but not more than 16 carbon atoms in the aliphatic radical. Very particularly preferably, as a further nonionic surfactant, 8-fold ethoxylated isododecan-l-ol, 1-dodecanol, isotridecan-l-ol, 1-tridecanol, tetradecan-l-ol and / or isotetradecan-l-ol is present in the alkaline cleaner.

[0052] Particularly preferred are mixtures of fatty amine alkoxylates and fatty alcohol alkoxylates, especially mixtures of the preferred representatives of these nonionic surfactants. The proportion of the other nonionic surfactants in the alkaline cleaner of the process according to the invention is preferably at least 0.5 g / kg, more preferably at least 1.0 g / kg, especially preferably at least 2 g / kg, and most preferably at least 3 g / kg, based on the cleaning composition.

[0053] In various embodiments, it is provided that the cleaner comprises less than 15 wt.%, preferably less than 10 wt.%, more preferably less than 5 wt.%, even more preferably less than 3 wt.%, in each case based on the total weight of the cleaner, of further fatty alcohol alkoxylates as nonionic surfactants with a degree of alkoxylation of < 8 EO.

[0054] Typically, the alkaline cleaner for use in a process according to the invention is derived from a cleaner concentrate, with which the system tank of the cleaner is prefilled and the application bath is ultimately prepared by dilution. In this context, concentrates are all concentrated compositions containing one or more active components of the alkaline cleaner, through which a ready-to-use alkaline cleaner can be produced simply by mixing them together and diluting them with water, for example, surface and / or groundwater treated as process water, water with a specific conductivity of less than 10 pScm. 1 or deionized water (K ​​< 1 pScm -1 ). The concentrate is therefore also suitable for refining the application bath as a whole or individual active components during the degreasing process of an entire series of components.

[0055] A preferred method within the scope of the present invention is characterized in that the cleaner, as described above, comprises additional surfactants, preferably with defoaming properties. Suitable surfactants with defoaming properties can be, for example, alkoxylated fatty alcohols.

[0056] A particularly suitable process according to the invention within the scope of the present invention is characterized in that the alkaline aqueous cleaner is obtainable by diluting a cleaner concentrate with water, preferably with deionized water (K ​​< 1 pScm -1 ), particularly preferably with water with a specific conductivity of less than 10 pScm 1and most preferably with process water, by a factor of 5 to 100. The alkaline aqueous cleaner with a pH above 8.5 comprises, based on the total weight of the cleaner, a) at least 0.10 wt.%, preferably at least 0.20 wt.%, particularly preferably at least 0.25 wt.% of a surfactant mixture comprising

[0057] (i) at least 50% by weight, preferably at least 65% by weight, particularly preferably at least 80% by weight, in each case based on the total amount of components (i) to (iii), of one or more surfactants selected from fatty alcohols alkoxylated with ethylene oxide (EO) and propylene oxide (PO) and having an EO:PO ratio of greater than 1:1;

[0058] (ii) less than 50% by weight, preferably less than 30% by weight, particularly preferably less than 20% by weight, but preferably at least 5% by weight, in each case based on the total amount of components (i) to (iii), of one or more surfactants selected from fatty alcohols alkoxylated with ethylene oxide (EO) and propylene oxide (PO) and having an EO:PO ratio of 1:1 or less;

[0059] (iii) optionally further surfactants, preferably with defoaming properties, particularly preferably selected from fatty amine alkoxylates and / or fatty alcohol alkoxylates, b) 0.10 to 5.0 wt.%, preferably 0.20 to 4.0 wt.%, particularly preferably 0.30 to 3.0 wt.% of alkali metal hydroxides, preferably selected from potassium hydroxide, calculated as KOH; c) 0.05 to 4.0 wt.%, preferably 0.10 to 3.0 wt.%, particularly preferably 0.20 to 2.0 wt.% of water-soluble phosphates, preferably selected from orthophosphates, pyrophosphates and / or tripolyphosphates, calculated as PO4, and / or carbonates calculated as CO3; d) optionally up to 1.0 wt.-% of organic complexing agents, preferably selected from a-hydroxycarboxylic acids, preferably selected from lactic acid, glycolic acid and / or gluconic acid and their water-soluble salts, di- and / or tricarboxylic acids, preferably selected from tartaric acid and / or citric acid and their water-soluble salts, and / or phosphonic acids, preferably selected from aminotrimethylenephosphonic acid and / or etidronic acid and their water-soluble salts, and e) water.

[0060] Definitions

[0061] In the context of the present invention, a surfactant is a surface-active organic compound that reduces the surface tension or interfacial tension between two liquids (e.g., between water and nonpolar oils) and aggregates in bulk phases to form micelle colloids or lyotropic mesophases. Surfactants are amphiphilic molecules, meaning they have both hydrophobic and hydrophilic moieties. This allows them to interact with both water and oils / lipids. Surfactants can be classified into anionic, cationic, nonionic, and zwitterionic based on the charge of their hydrophilic moieties.

[0062] For the purposes of the present invention, a surfactant is considered to have defoaming properties if it is capable of bringing the cloud point of the cleaner into the range of the application temperature, thereby reducing the cleaner's tendency to foam. Suitable surfactants with defoaming properties can be, for example, alkoxylated fatty alcohols.

[0063] Not each of the components (i) to (iii) represents an essential feature of the compositions according to the invention. The phrase (or similar phrases) "based on the total weight of components (i) to (iii)" should be understood to refer to the combined total weight of those components (i) to (iii) actually present in a particular composition. For example, if only components (i) and (ii) are present and component (iii) is not, in this context the phrase "based on the total weight of components (i) to (iii)" corresponds to the combined total weight of components (i) and (ii).This means that this wording should not be understood to mean that each of the components (i) to (iii) must be present (unless they have been identified as essential), but rather that it is the combined total weight of those of these components that are actually present in a particular composition.

[0064] In the compositions disclosed herein where amounts are expressed in weight percent (wt%), for example based on the total weight of the components present in the composition (e.g. the total weight of the surfactants and foaming agents present), the combined amounts, expressed in wt%, of each of the individual components present in the composition may not exceed 100 wt%.

[0065] For the purposes of the present invention, the term "liquid" includes liquids and gels, as well as pasty compositions. This statement refers, unless otherwise stated, to standard conditions. The liquid compositions are preferably flowable and pourable under standard conditions; it is also possible for them to be a non-Newtonian fluid with a yield point, i.e., the fluid is a pseudoplastic (increasing viscosity with increasing shear forces) or dilatant (increasing viscosity with increasing shear rate) fluid.

[0066] In the context of the present invention, the term "solid" refers to compounds / compositions that are solid under standard conditions, i.e., the said compounds / compositions are neither in liquid nor gaseous form. The solids are preferably in powder, granulate, or compact form.

[0067] For the purposes of the present invention, "standard conditions" are synonymous with "normal temperature and pressure", which are defined as a temperature of 21±1 °C and an absolute pressure of 101.325 kPa (1 atm).

[0068] Unless otherwise stated here, atmospheric pressure is 101.325 kPa.

[0069] Unless otherwise stated, room or ambient temperature is 21±1 °C.

[0070] Unless otherwise stated, all measurements and procedures disclosed herein are understood to have been performed under standard conditions.

[0071] Unless expressly stated otherwise, all percentages given herein with respect to the compositions or formulations refer to percentages by weight (wt%) based on the total weight of the respective composition.

[0072] Unless explicitly stated otherwise, numerical values ​​expressed without decimal places refer to the full value, while those expressed with one decimal place refer to the full value. For example, 99% represents 99.0%.

[0073] In the context of the present application, the term "essentially free" refers to the fact that the compound / solvent / etc. from which the composition or material in question is essentially free may nevertheless be present in small amounts (e.g., as impurities in other components present in the composition in question—for example, commercially available solvents may contain small amounts of, for example, acetone or methyl ethyl ketone as undesirable impurities) that do not, however, affect the desired properties attributed to the compositions of the present technology. "Essentially free" in this context may mean that the compound, solvent, etc.from which the composition or material in question is essentially free may be present in an amount of 1000 ppm or less, 750 ppm or less, 500 ppm or less, 300 ppm or less, 200 ppm or less, 100 ppm or less, 50 ppm or less, or 10 ppm or less.

[0074] The mention of a document in this document does not constitute an admission that said document or its contents are within the common knowledge of the person skilled in the art. The term "comprise," as used herein, is synonymous with "containing" and does not exclude additional, unlisted elements or process steps. According to the present invention, the term "comprise" also encompasses the term "consist essentially of" or "consist of," meaning that "comprise" may be replaced by the other terms in alternative embodiments, where "consist of" excludes any element or step not expressly mentioned, and "consist essentially of" allows the inclusion of additional, unlisted elements or steps that do not significantly affect the essential or fundamental characteristics of the composition or process in question.

[0075] Where a numerical range is specified herein, that range is continuous and includes both the minimum and maximum values ​​of the range, as well as every value between those minimum and maximum values. Where a range refers to whole numbers, every whole number between the minimum and maximum values ​​of such a range is included. Where multiple ranges are specified to describe a feature or characteristic, those ranges may be combined. This means that, unless expressly stated otherwise, all ranges disclosed herein are to be understood to include all subranges contained therein. For example, a specified range of "1 to 10" is to be understood to include all subranges between the minimum value of 1 and the maximum value of 10, including the values ​​1 and 10. Example subranges of the range 1 to 10 include, but are not limited to, 1 to 6.1, 3.5 to 7.8, and 5.5 to 10.The disclosed upper and lower limits for quantity, range and ratio can be combined independently.

[0076] Any feature of the invention which is intended to be present in a particular range or in a particular amount may be combined in a corresponding embodiment with the other features of that embodiment, wherein the other features may be present in the ranges or amounts disclosed herein for said other features.

[0077] All ranges and amounts for one feature of an embodiment can be combined with all ranges and amounts of the other features in that embodiment. For example, ranges or values ​​stated as preferred, more preferred, or most preferred for one feature or component of the invention can be combined with any range or amount stated for any other feature or component of the embodiment, regardless of whether the range or amount stated for the other element is labeled as preferred, more preferred, or most preferred, etc., or is disclosed without such labeling or indication. The singular forms used herein (e.g., "a" or "a") include the plural unless the context clearly indicates otherwise.

[0078] The term "at least one," as used herein, includes, but is not limited to, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or more. When referring to an ingredient, the statement refers to the type of ingredient and not to the absolute number of molecules. To clarify the foregoing, "at least one alcohol" means at least one type of alcohol, meaning that it can refer to one type of alcohol or a mixture of several different alcohols. The same applies to expressions that refer to a higher number (e.g., "at least two", "at least three", etc.), each of which begins with a higher number (e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10 or more for "at least two"; 3, 4, 5, 6, 7, 8, 9, 10 or more for "at least three"; etc.).

[0079] Unless expressly stated otherwise, molar mass data always refer to the weight-average molar mass (Mw).

[0080] Examples

[0081] The examples listed below are intended only to illustrate certain embodiments of the invention and in no way limit the scope of the invention described herein and claimed in the claims.

[0082] Unless explicitly stated otherwise, all syntheses and measurement methods of parameters were carried out at room or ambient temperature, ie at 21±1 °C, and atmospheric pressure.

[0083] Unless explicitly stated otherwise, technically pure reagents were used.

[0084] All reagents used in the examples described below were purchased commercially under the indicated product names.

[0085] Measurement methods

[0086] Molar mass

[0087] The number-average and weight-average molecular weights can be determined, for example, by gel permeation chromatography (GPC) according to DIN 55672-1:2007-08 using THF as eluent.

[0088] Experimental data: The tested surfactants contain 2-ethylhexanol as the fatty alcohol, which was functionalized with EO and PO. The EO / PO functionalization is summarized in Table 1.

[0089] Table 1 : tested surfactants

[0090] The compositions tested are summarized in Table 2.

[0091] Table 2: Overview of the components of the surfactant mixtures used in wt-%

[0092] The comparison surfactant is coconut amine, which is alkoxylated with about 12 ethylene oxide units.

[0093] The defoamer is an ethylene oxide / propylene oxide copolymer based on a C13 / C15 alcohol.

[0094] Comparison of the cleaning effect of additives in immersion cleaning with alkaline cleaners

[0095] Steel Q-panels (ST1404) were pre-cleaned with an alkaline cleaner (2% BONDERITE C-AK 6444, 0.2% BONDERITE C-AD 0469, and deionized water). For this purpose, the Q-panels were fully immersed in the solution. The panels were then immersed in water at a frequency of approximately 1 Hz 20 times. This step was repeated with deionized water. Finally, the panels were dried with compressed air. The resulting pre-cleaned and dried panels were immersed in oil (100% Anticorit 4107S) at room temperature. The treated panels were hung at room temperature for 15 minutes to allow them to dry. They were then immersed in a thermostatically controlled bath equipped with a Thermo Fisher Scientific DC30 circulation pump. Cleaning was carried out at 35 °C for a period of 300 s.

[0096] Cleaning compositions containing the surfactant mixtures listed in Table 2 were provided for the bath. The cleaning compositions include the components shown in Table 3.

[0097] Table 3: Overview of the components of the cleaning compositions

[0098] The cleaning performance was determined using a SITA CleanoSpector (SITA Messtechnik GmbH). The fluorescence of a layer of dirt is stimulated by a UV light source, and a photodiode in the sensor head of the SITA CleanoSpector measures the intensity of the radiation emitted by the fluorescence at a specified wavelength in the blue light range. The higher the measured intensity, the more severe the surface contamination. Organic substances such as oils exposed to UV light exhibit intrinsic fluorescence. This makes it possible to determine the degree of contamination. The resulting RFU value is acceptable if it is below 10.

[0099] For the water break test (wettability of the surface), the degreased panel is completely immersed in a container at room temperature for 1 min and then rinsed with deionized water (K ​​< 1 pScm -1). The vessel has a continuous fresh water supply (process water) of 120 ± 20 L / h (the quantity is to be determined by calibrating). Wettability is assessed after the panel has been removed. A continuous water film should be maintained for 10 seconds after removal, with the panel remaining vertical during this time. The water-wettable surface is given as a percentage of the total surface. Water wettability is "OK" if the entire surface remains completely wetted (100%) with water for at least 10 seconds after cleaning and subsequent rinsing with water.

[0100] The stability of the diluted cleaning composition was determined visually. A non-homogeneous solution or a solution with phase separation was considered unstable (stability is not known).

[0101] The cleaning performance was OK if, after 60 seconds of treatment time, less than 15 mg / m 2of carbon residues were detected. The amount of carbon remaining on the surface of the layer is determined after pyrolytic decomposition. For this purpose, a sheet metal section of a defined area is heated to a substrate temperature (PMT) of 550°C in an oxygen atmosphere in a furnace, and the amount of carbon dioxide released is quantitatively determined as the amount of carbon using an infrared sensor and the LECO® RC-412 Multiphase Carbon Determinator (Leco Corp.).

[0102] The results achieved by the tested compositions are summarized in Table 4.

[0103] Table 4: Results of the cleaning test with the cleaning compositions comprising the surfactant mixtures according to Examples 1 to 9

[0104] Examples 3 to 6 are stable. However, their cleaning performance is sufficient.

[0105] In contrast, examples 1 and 2 have good cleaning performance, whereas their stability is insufficient.

[0106] In direct comparison to examples 1 and 2, but also 3 to 6, the above-mentioned examples 7 to 9 show an outstanding performance in that not only the required cleaning performance of low-temperature applications is achieved, but also that the stability of the cleaner is ensured.

Claims

Claims:

1. A method for degreasing the metallic surfaces of a component, in which at least the metallic surfaces of the component are brought into contact with an alkaline aqueous cleaner, the temperature of the cleaner being below 50 °C during contact, and the cleaner comprising a surfactant mixture containing components (i)-(iii): (i) at least one or more surfactants selected from fatty alcohols alkoxylated with ethylene oxide (EO) and propylene oxide (PO) having an EO:PO ratio greater than 1:1, (ii) at least one or more surfactants selected from fatty alcohols alkoxylated with ethylene oxide (EO) and propylene oxide (PO) having an EO:PO ratio of 1:1 or less, and (iii) optionally further surfactants, preferably with defoaming properties, wherein the surfactant mixture contains at least 50% by weight of component (i), based on the total amount of components (i) to (iii).

2. Method according to claim 1, characterized in that the contacting of the cleaner is carried out by spraying and / or dipping, preferably by immersing the component in a system tank containing the cleaner.

3. Method according to one or both of the preceding claims, characterized in that the degreasing takes place at a temperature of the cleaner below 50.0 °C, preferably below 45.0 °C, particularly preferably below 40.0 °C and especially preferably below 35.0 °C.

4. Method according to one or more of the preceding claims, characterized in that the metallic surfaces of the component are surfaces of the materials aluminum, steel, galvanized steel and / or alloy-galvanized steel, preferably of the material aluminum and its alloys.

5. Process according to one or more of the preceding claims, characterized in that the weight-average molecular mass of components (i) and (ii) of the surfactant mixture is less than 2000 g / mol, preferably less than 1500 g / mol, particularly preferably less than 900 g / mol and most particularly preferably less than 700 g / mol.

6. Process according to one or more of the preceding claims, characterized in that components (i) and (ii) of the surfactant mixture contain up to 30 units of ethylene oxide (EO) and propylene oxide (PO), preferably up to 20 units of ethylene oxide (EO) and propylene oxide (PO), particularly preferably up to 15 units of ethylene oxide (EO) and propylene oxide (PO), and very particularly preferably up to 10 units of ethylene oxide (EO) and propylene oxide (PO).

7. Method according to one or more of the preceding claims, characterized in that - component (i) of the surfactant mixture has an EO:PO ratio in a range from 1.5:1 to 1:1.05, preferably 1.3:1 to 1.1:1, more preferably 1.3:1 to 1.2:1, and particularly preferably an EO:PO ratio of 1.25:1; and / or - component (ii) of the surfactant mixture has an EO:PO ratio in a range from 1:1 to 1:3, preferably 1:1.5 to 1:2.

5.

8. Method according to one or more of the preceding claims, characterized in that the hydrophobic residue (i) is linear or branched, preferably branched; (ii) an aliphatic monohydric alcohol, preferably an even-numbered fatty alcohol, more preferably a Ce to C22 fatty alcohol, especially preferably a Ce to C8 fatty alcohol, even more preferably a Ce to C12 fatty alcohol, further preferably a C8 to C10 fatty alcohol and most preferably a C8 fatty alcohol; (iii) a saturated, monounsaturated or polyunsaturated fatty alcohol, preferably a fully saturated fatty alcohol.

9. Process according to one or more of the preceding claims, characterized in that the hydrophobic radical is a fatty alcohol, wherein the fatty alcohol is 2-propyl-l-pentanol and / or 2-ethyl-l-hexanol, preferably 2-ethyl-l-hexanol.

10. Process according to one or more of the preceding claims, characterized in that the surfactant mixture of the cleaner contains, based on the total amount of components (i) to (iii), at least 65% by weight of component (i), preferably at least 80% by weight of component (i).

11. Process according to one or more of the preceding claims, characterized in that the surfactant mixture of the cleaner, based on the total amount of components (i) to (iii), contains less than 30% by weight of component (ii), preferably less than 20% by weight of component (ii), but preferably at least 5% by weight of component (ii).

12. Method according to one or more of the preceding claims, characterized in that in the alkaline aqueous cleaner at least one alkaline reacting, inorganic compound based on water-soluble hydroxides, carbonates, borates, silicates and / or phosphates, wherein preferably at least water-soluble phosphates are contained, which in turn are preferably selected from orthophosphates, pyrophosphates and / or tripolyphosphates.

13. Process according to one or more of the preceding claims, characterized in that the alkaline aqueous cleaner has a pH value above 8.5, preferably above 9.0, but preferably below 11.0, particularly preferably below 10.

0.

14. The method according to one or more of the preceding claims, characterized in that the alkaline aqueous cleaner contains at least one non-ionic surfactant as component (iii) of the surfactant mixture, which differs from the surfactants according to components (i) and (ii) and has an HLB value above 10.0, preferably above 11.0, particularly preferably above 12.0, which is preferably selected from fatty amine alkoxylates with preferably at least 8, but fewer than 14 EO units and / or fatty alcohol alkoxylates with preferably at least 6, but fewer than 10 EO units.

15. Alkaline aqueous cleaner with a pH above 8.5, which contains, based on the cleaner, a) at least 0.10 wt.%, preferably at least 0.20 wt.%, particularly preferably at least 0.25 wt.% of a surfactant mixture comprising (i) at least 50% by weight, preferably at least 65% by weight, particularly preferably at least 80% by weight, in each case based on the total amount of components (i) to (iii), of one or more surfactants selected from fatty alcohols alkoxylated with ethylene oxide (EO) and propylene oxide (PO) and having an EO:PO ratio of greater than 1:1; (ii) less than 50% by weight, preferably less than 30% by weight, particularly preferably less than 20% by weight, but preferably at least 5% by weight, in each case based on the total amount of components (i) to (iii), of one or more surfactants selected from fatty alcohols alkoxylated with ethylene oxide (EO) and propylene oxide (PO) and having an EO:PO ratio of 1:1 or less; (iii) optionally further surfactants, preferably with defoaming properties, particularly preferably selected from fatty amine alkoxylates and / or fatty alcohol alkoxylates, b) 0.10 to 5.0 wt.%, preferably 0.20 to 4.0 wt.%, particularly preferably 0.30 to 3.0 wt.% of alkali metal hydroxides, preferably selected from potassium hydroxide, calculated as KOH; c) 0.05 to 4.0 wt.%, preferably 0.10 to 3.0 wt.%, particularly preferably 0.20 to 2.0 wt.% of water-soluble phosphates, preferably selected from orthophosphates, pyrophosphates and / or tripolyphosphates, calculated as PO4, and / or carbonates calculated as CO3; d) optionally up to 1.0% by weight of organic complexing agents, preferably selected from a-hydroxycarboxylic acids, preferably selected from lactic acid, glycolic acid and / or gluconic acid and their water-soluble salts, di- and / or tricarboxylic acids, preferably selected from tartaric acid and / or citric acid and their water-soluble salts, and / or phosphonic acids, preferably selected from aminotrimethylenephosphonic acid and / or etidronic acid and their water-soluble salts, and e) water.

Images