Improved activator for manganese phosphate treatment process

Abstract

The present invention relates to an alkaline aqueous activator for a manganese phosphate treatment process, comprising: a) nanoscale manganese phosphate particles in dispersed form; and b) at least one dispersant selected from the group consisting of homopolymers containing at least one monomer unit having at least one carboxylate group and copolymers containing at least one monomer unit having at least one carboxylate group. The present invention also relates to a method for preparing the activator, an improved manganese phosphate treatment process utilizing the activator, and metal substrates, particularly steel substrates, phosphated thereby.

Description

[Technical Field]

[0001] The present invention relates to an improved activator for a manganese phosphate treatment process, a method for producing the same, an improved manganese phosphate treatment process using the activator, and a phosphate-treated metal substrate, particularly a steel substrate, thereby. [Background technology]

[0002] Acidic aqueous manganese phosphate systems are used, in particular, to phosphorylate steel substrates, especially engine components such as engine transmissions or pipe fittings in oil fields. The phosphorylated substrates exhibit not only improved corrosion resistance but also reduced sliding friction. In addition to manganese and phosphate ions, the manganese phosphate system preferably contains iron(II) and / or nickel ions in a dissolved form.

[0003] In order to form a crystalline phosphate layer (e.g., one made of heuriolite) on the surface of a substrate to be coated, the surface must first be activated; that is, phosphate crystals must be deposited as crystallization nuclei. This is achieved by applying such an activator to the surface.

[0004] In the production of activators for manganese phosphate treatment processes, dried manganese phosphate is typically ground using a dry mill to obtain manganese phosphate powder, which is then dispersed in an alkaline aqueous composition.

[0005] However, the activator obtained in this way has a drawback: if not continuously stirred, the manganese particles will settle, and further activation will be impossible. Due to this tendency to settle, there is always a risk that manganese phosphate residue will precipitate on the surface of the substrate, resulting in insufficient adhesion and homogeneity of the subsequent phosphate layer.

[0006] Furthermore, such activators must be applied at fairly high concentrations. This is because they have a particle size of several micrometers (typically about 3 μm). 50 This is because the activation is not very efficient due to the value. For the same reason, the subsequent manganese phosphate treatment process must be carried out at a relatively high temperature, typically in the range of 80-90°C. [Overview of the project] [Problems that the invention aims to solve]

[0007] Therefore, the fundamental problem of the present invention is to provide an improved activator for manganese phosphate treatment processes that avoids the drawbacks of the prior art activators described above. [Means for solving the problem]

[0008] This problem relates to the activator described in claim 1, that is, a) Nanoscale manganese phosphate particles in a dispersed form, and b) At least one dispersant selected from the group consisting of homopolymers containing at least one monomer unit having at least one carboxylic acid base and copolymers containing at least one monomer unit having at least one carboxylic acid base, This is resolved by alkaline aqueous activators, including [specific component].

[0009] By using at least one dispersant according to b), the viscosity of the corresponding concentrate for producing the activator becomes suitable, neither too high nor too low. This is because if the viscosity is too high, problems arise when removing the concentrate from its storage container, while if the viscosity is too low, irreversible phase separation may occur after approximately two weeks of storage. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 shows the particle size distribution before wet grinding. [Figure 2]Figure 2 shows the particle size distribution after wet grinding. [Figure 3] Figure 3 shows the SEM image. [Figure 4] Figure 4 shows the SEM image.

Mode for Carrying Out the Invention

[0011] Definition: In the present invention, the "aqueous composition" means that 35 mass percent or more of the composition is water, and preferably deionized water is used.

[0012] The "nanoscale (...) particles" are understood to have a d value of less than 1.0 μm in the particle size distribution. 90 value less than 1.0 μm.

[0013] "Dispersed form" means that the particles are distributed in a continuous aqueous phase, and when the composition is gently left standing for a long time, dispersion can be obtained and the particles do not settle, that is, the heterogeneous mixture is a colloid, or, if the particles partially settle, the fluid dispersion can be restored by shaking the composition for a short time.

[0014] Therefore, the "dispersant" means a composition that stabilizes the distribution of particles in a continuous aqueous phase to obtain a colloid, or, if the particles partially settle after a long time, the fluid dispersion can be restored by shaking the composition for a short time.

[0015] Here, "wt.-% (mass%)" is an abbreviation for mass percent, that is, the value obtained by dividing the mass of the composition by the total mass of the composition.

[0016] "Carboxylate group" means a deprotonated, that is, neutralized form of a carboxylic acid group.

[0017] As used herein, “(meth)acryl” is an abbreviation for acrylic, methacrylic, or a mixture of acrylic and methacrylic. Correspondingly, “copolymer of (meth)acrylic acid” means a polymer containing other monomer units not derived from (meth)acrylic acid.

[0018] The manganese phosphate nanoparticles preferably have a particle size distribution with a d value of less than 0.8 μm, more preferably less than 0.7 μm, even more preferably less than 0.6 μm, and most preferably less than 0.5 μm. 90 show a particle size distribution with a value of.

[0019] Furthermore, the d value of the particle size distribution is preferably less than 0.5 μm, more preferably less than 0.4 μm, and most preferably less than 0.3 μm, while the d value is preferably less than 0.3 μm and more preferably less than 0.2 μm. 50 while the d value is preferably less than 0.3 μm and more preferably less than 0.2 μm. 10 The particle size distribution including the d value, d value, and d value may be determined by a Mastersizer 2000 (Malvern Instruments, UK) according to the manufacturer's operating manual.

[0020] d 10 d 50 and d 90 The particle size distribution including the d value, d value, and d value may be determined by a Mastersizer 2000 (Malvern Instruments, UK) according to the manufacturer's operating manual.

[0021] Preferably, at least 35% by mass, more preferably at least 50% by mass, and even more preferably at least 65% by mass of the manganese phosphate nanoparticles are crystalline. The proportion of such nanocrystalline particles may be determined by wide-angle X-ray scattering (WAXS).

[0022] In the alkaline aqueous activator, the concentration of the manganese phosphate nanoparticles is preferably in the range of 1.0 to 8.0×10% by mass, more preferably in the range of 2.0 to 7.0×10% by mass, and most preferably in the range of 2.5 to 6.5×10% by mass. -3 more preferably in the range of 2.0 to 7.0×10% by mass, -3 and most preferably in the range of 2.5 to 6.5×10% by mass. -3 is in the range.

[0023] In prior art, manganese phosphate powder obtained by dry grinding manganese phosphate requires a concentration of approximately 0.1 to 0.3% by mass in the dispersion. In comparison, the concentration of dispersed nanoscale manganese phosphate particles according to the present invention is approximately 100 times lower, demonstrating the latter's significantly greater efficiency.

[0024] The at least one dispersant is preferably selected from the group consisting of homopolymers containing at least one monomer unit having at least one carboxylic acid base and copolymers containing at least one monomer unit having at least one carboxylic acid base, where the at least one monomer unit constitutes at least 35 mol%, more preferably at least 50 mol%, even more preferably at least 65 mol%, and most preferably at least 80 mol% of the monomer units of such copolymer.

[0025] Preferably, at least one dispersant comprises at least one salt of at least one homopolymer or copolymer of (meth)acrylic acid, more preferably at least one salt of at least one homopolymer or copolymer of acrylic acid. Preferred homopolymers and copolymers are linear. Preferred copolymers are those with maleic acid. Preferred salts are sodium salts or potassium salts, with sodium salts being particularly preferred.

[0026] According to a preferred embodiment, at least one dispersant comprises a sodium salt of an acrylic acid homopolymer and / or a copolymer of acrylic acid and maleic acid, preferably a sodium salt of an acrylic acid homopolymer and / or a copolymer of acrylic acid and maleic acid.

[0027] Aron A6020 (Toagosei, Japan) or Dispex® N40 (Chiba, Switzerland) are particularly preferred and commercially available dispersants.

[0028] The overall concentration of at least one dispersant in the aqueous alkaline activator is preferably 0.04 × 10⁻⁶. -3Higher, more 0.12 × 10 -3 , and more preferably 0.16 × 10 -3 This is expressed in mass percent. The concentration is 0.04 × 10⁻⁶. -3 If the concentration is less than mass%, not all nanoscale manganese phosphate particles may be present in a dispersed form. However, high concentrations of the dispersant may reduce the storage stability of the alkali activator, particularly due to increased susceptibility to bacterial contamination. Therefore, the overall concentration of at least one dispersant is preferably 0.80 × 10⁻⁶. -3 Less than, more preferably 0.64 × 10 -3 , and more preferably 0.48 × 10 -3 It is expressed as mass percent.

[0029] The overall concentration of at least one dispersant is more preferably 0.04 to 0.80 × 10 -3 In the range of mass%, more preferably 0.12 to 0.64 × 10 -3 In the range of mass%, more preferably 0.16 to 0.48 × 10 -3 In the range of mass% and most preferably 0.18 to 0.42 × 10 -3 It is within the range of mass percent.

[0030] With respect to the mass percentage concentration of the activator, the nanoscale manganese phosphate particles and at least one dispersant preferably exhibit a ratio in the range of 1.2:1 to 200:1, more preferably in the range of 3:1 to 60:1, and even more preferably in the range of 5.2:1 to 41:1.

[0031] In addition to components a) and b), namely nanoscale manganese phosphate particles and at least one dispersant, the alkaline aqueous activator may further contain advantageous components, in particular at least one additive. Particularly preferred additives are selected from the group consisting of biocides and pH adjusters including buffer systems. Furthermore, the addition of at least one defoamer may be advantageous.

[0032] Preferably, the activator comprises c) at least one biocide, the total concentration of which is preferably in the range of 0.1 to 0.5% by mass. A preferred biocide is Acticide® MBS50 (Thor, Germany).

[0033] The pH value of the activator is higher than 7.0, preferably in the range of 7.5 to 10.0, and more preferably in the range of 8.5 to 10.0.

[0034] Preferably, the activator includes c) at least one buffering system.

[0035] The present invention also relates to a method for producing an alkaline aqueous activator, wherein water and a) Manganese phosphate, and b) At least one dispersant selected from the group consisting of homopolymers containing at least one monomer unit having at least one carboxylic acid base and copolymers containing at least one monomer unit having at least one carboxylic acid base. A mixture containing the above is wet-milled in a bead mill, preferably a stirring bead mill, until an aqueous concentrate containing nanoscale manganese phosphate particles in a dispersed form is obtained, from which an alkaline aqueous activator is obtained by diluting with water, preferably at a coefficient in the range of 1:4,000 to 1:12,000 relative to volume, and by adding at least one pH adjuster if necessary.

[0036] Manganese phosphate a) is preferably heurolith, and its concentration is in the range of 25 to 35% by mass in the mixture to be ground, which is advantageous in terms of the suitable viscosity of the mixture to be ground.

[0037] The use of at least one dispersant according to (b) results in a sufficiently low viscosity of the mixture to be ground, so that the mobility of the beads in the grinding chamber and the throughput of the material are sufficiently high during the grinding process, and nanoscale manganese phosphate particles are obtained in a dispersed form.

[0038] The at least one dispersant is preferably selected from the group consisting of homopolymers containing at least one monomer unit having at least one carboxylic acid base and copolymers containing at least one monomer unit having at least one carboxylic acid base, where the at least one monomer unit constitutes at least 35 mol%, more preferably at least 50 mol%, even more preferably at least 65 mol%, and most preferably at least 80 mol% of the monomer units of such copolymer.

[0039] Preferably, at least one dispersant in the mixture to be ground contains at least one salt of at least one homopolymer or copolymer of (meth)acrylic acid, more preferably at least one salt of at least one homopolymer or copolymer of acrylic acid. Preferred homopolymers and copolymers are linear. Preferred copolymers are those with maleic acid. Preferred salts are sodium salts or potassium salts, with sodium salts being particularly preferred.

[0040] According to a preferred embodiment, at least one dispersant comprises a sodium salt of an acrylic acid homopolymer and / or a copolymer of acrylic acid and maleic acid, preferably a sodium salt of an acrylic acid homopolymer and / or a copolymer of acrylic acid and maleic acid.

[0041] Aron A6020 (Toagosei, Japan) or Dispex® N40 (Chiba, Switzerland) are particularly preferred and commercially available dispersants.

[0042] The overall concentration of at least one dispersant in the mixture to be ground is preferably in the range of 1 to 10% by mass, more preferably in the range of 3 to 8% by mass, and even more preferably in the range of 4 to 6% by mass, which is advantageous in terms of the suitable viscosity of the mixture to be ground.

[0043] A bead mill contains a large number of beads packed into a grinding chamber. In the case of agitated bead mills, grinding is supported by an agitation shaft located within the grinding chamber. In particular, the agitation shaft is a cylinder with a row of knobs on its surface (e.g., Grinding Systems MiniFer, NEOS, ZETA®, and MACRO, Netzsch, Germany) or a rotor with several parallel discs (e.g., DYNA®-MILL, WAB, Switzerland).

[0044] When the volume of the beads is 88% or more, preferably 92% or more, of the total volume of the mixture filled in the grinding chamber, and the rotation speed of the mill during the grinding process is less than 3,400 rpm, preferably less than 3,200 rpm, an activator with particularly suitable viscosity and especially small particle size can be obtained.

[0045] After grinding, at least one further component c), particularly at least one additive, may be added to the mixture. Particularly preferred additives are selected from the group consisting of biocides and pH adjusters, including buffer systems. Furthermore, the addition of at least one defoamer may be advantageous.

[0046] Further preferred features and embodiments of the method for producing the activator can be obtained from the activator of the present invention described above.

[0047] The present invention also relates to an aqueous concentrate for producing the alkaline aqueous activator of the present invention, wherein the alkaline aqueous activator of the present invention is obtained by diluting the concentrate with water, preferably at a coefficient in the range of 1:4,000 to 1:12,000 by volume, and, if necessary, by adding at least one pH adjuster.

[0048] The present invention also provides an improved manganese phosphate treatment process, namely, the following steps: i) A step of bringing a preferably cleaned and / or pickled metal substrate, particularly a steel substrate, into contact with an alkaline aqueous activator according to the present invention. ii) Optionally, a step of rinsing the metal substrate, iii) A step of contacting a metal substrate with an acidic aqueous manganese phosphate system containing manganese, phosphoric acid, and preferably iron(II) and / or nickel ions in a dissolved form. iv) Optionally, a step of rinsing the metal substrate. v) A step of drying the metal substrate, vi) Optionally, coating the metal substrate with at least one oil, emulsion, and / or polymer, preferably for corrosion prevention purposes. This relates to a manganese phosphate treatment process, including [specific details omitted].

[0049] Compared with prior art manganese phosphate treatment processes that utilize manganese phosphate powder obtained by dry grinding, the manganese phosphate treatment process according to the present invention is - Lower energy costs - Less consumption of activators and manganese phosphate systems, and - Less debris in the activated bath and less scale in the phosphate-treated bath. This indicates.

[0050] The metal substrate is preferably a steel substrate, particularly an engine component such as an engine transmission or a pipe fitting for use in an oil field. In such cases, it is important not only to have improved corrosion resistance but also to reduce sliding friction.

[0051] If the substrate is washed before step i), it is preferable to use an alkaline cleaning agent that does not contain silicates. Furthermore, the washing is preferably carried out at a temperature in the range of 50 to 85°C for, for example, 10 minutes.

[0052] If the substrate is pickled with acid before performing step i), it is preferable to use a mineral acid such as phosphoric acid for the pickling.

[0053] Step i) of the method of the present invention is preferably carried out by immersing the substrate in an activator at room temperature for, for example, 1 minute.

[0054] When performing the cleaning in step 2), it is preferable to immerse the substrate in cold tap water for, for example, 1 minute. The same applies to any optional rinsing step iv).

[0055] Due to the use of the activator of the present invention, step iii) of the process of the present invention may be carried out at a temperature of less than 80°C, preferably less than 75°C, or more preferably less than 65°C. Step iii) is preferably carried out by immersing the substrate in the activator for, for example, 10 minutes.

[0056] The manganese phosphate system in step iii) preferably contains nitroguanidine as a phosphorylation accelerator, with a concentration preferably in the range of 0.5 to 3 g / l, more preferably in the range of 1 to 2 g / l. The addition of nitroguanidine also contributes to lowering the temperature in step iii).

[0057] In a manganese phosphate system, the ratio of total acid to free acid is preferably in the range of 5 to 15, more preferably in the range of 8 to 12. The total acid in the manganese phosphate system is determined by the following procedure.

[0058] Place 5 ml of phosphate bath into an Erlenmeyer flask using a pipette, dilute with approximately 50 ml of distilled water, and add 10-15 drops of phenolphthalein pH indicator. Then, titrate the sample with a 0.1 M sodium hydroxide solution until its color changes to red. Here, the total acid of the phosphate bath is obtained by dividing the amount of hydroxide solution consumed by ml and multiplying by 2.

[0059] The free acid is determined as follows:

[0060] 5 ml of phosphate bath is pipetted into an Erlenmeyer flask and diluted with approximately 50 ml of distilled water. One drop of dimethyl yellow pH indicator is then added. Next, the sample is titrated with a 0.1 M sodium hydroxide solution until its color changes to yellow. Here, the free acid of the phosphate bath is obtained by dividing the amount of hydroxide solution consumed by ml and multiplying by 2.

[0061] The selection of the ratio of total acid to free acid also helps to lower the temperature in step iii).

[0062] Step v) is preferably carried out by oven, preferably at a temperature in the range of 100 to 120°C for a period of 5 to 20 minutes, or by compressed air.

[0063] Further preferred features and embodiments of the manganese phosphate treatment process can be derived from the activator of the present invention described above.

[0064] Finally, the present invention also relates to a phosphate-treated metal substrate, particularly a steel substrate, which can be obtained by the manganese phosphate treatment process according to the present invention. Compared with the prior art phosphate layer obtained by the prior art phosphate treatment process described above, the phosphate layer obtained by the process of the present invention is i) More homogeneous, ii) Having a reduced coating mass, iii) It consists of finer crystals.

[0065] As a result, surfaces that have been phosphorylated in this way exhibit improved performance, particularly in terms of corrosion resistance and low sliding friction.

[0066] The present invention will be further explained below with reference to examples and comparative examples, but this will not limit the scope of the present invention. [Examples]

[0067] A) Grinding parameters: A mixture consisting of water, 30% by mass of manganese phosphate (Hurolith), and 5% by mass of Aron A6020 (Toagosei, Japan) (2% by mass relative to the polymer) was wet-milled for 4 hours using zirconium oxide beads with a diameter of 0.5–0.7 mm in a MiniFer stirred bead mill (Netzsch, Germany). In each case, the total volume of the mixture and zirconium oxide beads was 160 ml, and the material throughput during the milling process was 250 ml / min.

[0068] The bead grinding parameters—volume, rotation speed, pressure, and temperature—were varied as shown in Table 1 below:

[0069] [Table 1] *) Percentage of beads in the total volume (i.e., the volume of beads and the volume of the mixture mentioned above), **) rpm = revolutions per minute, ***) If the temperature rises above 30°C due to friction, water cooling is automatically initiated.

[0070] In all combinations of parameters applied in Examples E1 to E9, concentrates with suitable viscosity (determined by Mastersizer2000 (Malvern Instruments, UK) according to the manufacturer's operating manual) and nanoscale manganese phosphate particle distribution were obtained.

[0071] However, in terms of viscosity and particle size, the best results were obtained from the combination of parameters applied in Examples E3 and E6.

[0072] B) Dispersant: A mixture consisting of water, 30% by mass of manganese phosphate (heuriolite), and 5% by mass of different dispersant products (approximately 2% by mass relative to the polymer in each case) was wet-milled using zirconium oxide beads with a diameter of 0.5–0.7 mm in a MiniFer stirred bead mill (Netzsch, Germany) for 4 hours (94% by volume of beads and a rotation speed of 3,000 rpm). In each case, the total volume of such mixture and zirconium oxide beads was 160 ml. The resulting concentrate was then diluted with water at a coefficient of 1:5,000 (by volume) and the pH was adjusted to 9.5.

[0073] Table 2 below shows the results obtained for the applied dispersant products and their corresponding concentrates and activators, regarding sufficiently low viscosity and compatibility with the subsequent manganese phosphate treatment process. Since there is always a certain amount of carryover in the phosphate treatment bath, the activator must not interfere with the phosphate treatment bath, i.e., it must be compatible with the phosphate treatment process.

[0074] [Table 2] +=Requirements met, -=The requirements were not met. nd = Not determined due to inappropriate viscosity

[0075] In the case of Disperbyk2080 (Comparative Example CE1), the viscosity of the resulting concentrate was too high, causing problems during the grinding process and when removing the concentrate from the storage container. On the other hand, in the case of Edaplan492 (Comparative Example CE2), the manganese phosphate treatment bath was completely inhibited due to the carryover of the activator.

[0076] In contrast, using Dispex® AA4140, Dispex® N40, and Aron A6020 resulted in activators with sufficiently low viscosity in the concentrate and suitable for the subsequent phosphate treatment process (Examples E10-E13).

[0077] C) Particle size analysis: The particle size distribution of manganese phosphate (huriolite) was determined using a Mastersizer2000 (Malvern Instruments, UK) according to the manufacturer's operating manual, before (Figure 1) and after (Figure 2) wet grinding, following the procedure described for Example E3 or E6 (see above).

[0078] As can be easily deduced by comparing Figures 1 and 2, the particle size distribution after wet grinding shifts significantly to particles with a diameter of less than 1 μm, i.e., nanoscale particles.

[0079] D) XPS and SEM surface analysis: Test panels made of cold-rolled steel (CRS) and hot-rolled steel (HRS) were treated as follows:

[0080] The panels were degreased by immersing them in a solution containing 50 g / l of alkaline cleaning agent (GC S5176, Chemetall, Germany) at 65°C for 10 minutes, and then rinsed by immersion in cold tap water for 1 minute.

[0081] Next, 6.0×10 -3 Wet-ground manganese phosphate (Huriolite) at mass% and 5% by mass of Aron A6020 (Toagosei, Japan) (with a pH of 9.5) were immersed in an aqueous dispersion at room temperature for 1 minute, and then phosphate-treated and activated by immersion in an acidic aqueous solution of manganese phosphate at 78°C for 10 minutes.

[0082] Afterward, the panels were rinsed in cold tap water for one minute, and then dried with compressed air.

[0083] Next, the mass of the phosphate coating was measured by the mass method, i.e., differential mass method, and the surface structure was visualized using a scanning electron microscope (SEM).

[0084] The average phosphate coating mass is 5-10 g / m². 2This is the coating mass obtained after activation using dispersed dry-ground manganese phosphate (prior art) of the same concentration (typically 15 g / m²). 2 It is significantly lower than (exceeding) [amount].

[0085] Compared to prior art, the phosphate coating was more homogeneous and, as can be seen in Figure 3, consisted of much finer crystals.

Claims

1. An alkaline aqueous activator for manganese phosphate treatment processes, a) Dispersed form, d less than 1.0 μm ９０ Nanoscale manganese phosphate particles exhibiting a particle size distribution with a value, and b) At least one dispersant selected from the group consisting of homopolymers containing at least one monomer unit having at least one carboxylic acid base and copolymers containing at least one monomer unit having at least one carboxylic acid base, including and The concentration of the aforementioned nanoscale manganese phosphate particles is 1.0 to 8.0 × 10 －３ An alkaline aqueous activator characterized by being within the range of mass percent.

2. The aforementioned nanoscale manganese phosphate particles are less than 0.7 μm in size. ９０ The alkaline aqueous activator according to claim 1, characterized by exhibiting a particle size distribution with a value.

3. The concentration of the aforementioned nanoscale manganese phosphate particles is 2.0 to 7.0 × 10 －３ The alkaline aqueous activator according to claim 1 or 2, characterized in that it is within the range of mass percent.

4. The alkaline aqueous activator according to any one of claims 1 to 3, characterized in that the at least one dispersant comprises at least one salt of at least one homopolymer or copolymer of (meth)acrylic acid.

5. The total concentration of the at least one dispersant is 0.04 to 0.80 × 10 －３ The alkaline aqueous activator according to any one of claims 1 to 4, characterized in that it is in the range of mass percent.

6. c) The alkaline aqueous activator according to any one of claims 1 to 5, characterized in that it comprises at least one biocide, and the total concentration of the biocide is in the range of 0.1 to 0.5% by mass.

7. An alkaline aqueous activator according to any one of claims 1 to 6, characterized in that the pH value is in the range of 7.5 to 10.

0.

8. A method for producing an alkaline aqueous activator according to any one of claims 1 to 7, comprising water and a) Manganese phosphate, and b) At least one dispersant selected from the group consisting of homopolymers containing at least one monomer unit having at least one carboxylic acid base and copolymers containing at least one monomer unit having at least one carboxylic acid base. A method characterized by wet grinding a mixture containing the above in a bead mill until an aqueous concentrate containing nanoscale manganese phosphate particles in a dispersed form is obtained, and then diluting the concentrate with water to obtain an alkaline aqueous activator.

9. The method according to claim 8, characterized in that at least one pH value adjusting agent is added to the aqueous concentrate.

10. The method according to claim 8 or 9, characterized in that the bead mill is a stirring bead mill.

11. The method according to any one of claims 8 to 10, characterized in that the at least one dispersant comprises at least one salt of at least one homopolymer or copolymer of (meth)acrylic acid.

12. The method according to any one of claims 8 to 11, characterized in that the total concentration of the at least one dispersant is in the range of 1 to 10% by mass, based on the mixture.

13. An aqueous concentrate for producing an alkaline aqueous activator according to any one of claims 1 to 7, characterized in that the activator can be obtained by diluting the concentrate with water.

14. An aqueous concentrate for producing an alkaline aqueous activator according to any one of claims 1 to 7, characterized in that the activator can be obtained by diluting the concentrate with water and adding at least one pH adjusting agent.

15. The following steps: i) A step of bringing a metal substrate into contact with an alkaline aqueous activator according to any one of claims 1 to 7, ii) Optionally, a step of rinsing the metal substrate, iii) A step of bringing the metal substrate into contact with an acidic aqueous manganese phosphate system containing manganese and phosphate ions in a dissolved form, iv) Optionally, a step of rinsing the metal substrate, v) A step of drying the metal substrate, vi) Optionally, a step of coating the metal substrate with at least one oil, emulsion, and / or polymer. A manganese phosphate treatment process characterized by including the following:

16. The manganese phosphate treatment process according to claim 15, characterized in that step iii) further comprises an acidic aqueous manganese phosphate system in a form in which iron(II) and / or nickel ions are dissolved.

17. The phosphate treatment process according to claim 15 or 16, characterized in that the manganese phosphate system of step iii) contains nitroguanidine as a phosphorylation accelerator.

18. The phosphate treatment process according to any one of claims 15 to 17, characterized in that in the manganese phosphate system of step iii), the ratio of total acid to free acid is in the range of 5 to 15.

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