CA2277336A1 - Stabilizers for hydroxylamine in copper-containing phosphating solution - Google Patents
Stabilizers for hydroxylamine in copper-containing phosphating solution Download PDFInfo
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- CA2277336A1 CA2277336A1 CA002277336A CA2277336A CA2277336A1 CA 2277336 A1 CA2277336 A1 CA 2277336A1 CA 002277336 A CA002277336 A CA 002277336A CA 2277336 A CA2277336 A CA 2277336A CA 2277336 A1 CA2277336 A1 CA 2277336A1
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
- C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
- C23C22/07—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing phosphates
- C23C22/08—Orthophosphates
- C23C22/12—Orthophosphates containing zinc cations
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
- C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
- C23C22/34—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing fluorides or complex fluorides
- C23C22/36—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing fluorides or complex fluorides containing also phosphates
- C23C22/364—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing fluorides or complex fluorides containing also phosphates containing also manganese cations
Abstract
The invention concerns an acid aqueous phosphating solution which contains zinc ions, phosphate ions, copper ions and hydroxylamine in free form, as a salt or hydroxylamine-cleaving compound, and additionally one or a plurality of hydroxylamine stabilizers selected from organic molecules having at least two heteroatoms per molecule or, in the case of polymers, at least one heteroatom per four carbon atoms. The invention also concerns an aqueous concentrate and an aqueous supplementary solution for the phosphating solution.
Description
"Stabilisers for hydroxylamine in copper-containing phosphating solutions"
This invention relates to phosphating solutions suitable for the production of crystalline zinc phosphate layers on steel, zinc-coated steel or steel coated with zinc alloy and also on aluminium and alloys thereof. In addition to zinc ions and phosphate ions, these phosphating solutions contain copper ions and also hydroxylamine in free, salt-like or bound form as accelerator.
The addition of small quantities of copper ions to phosphating baths has already been known for 40 years. Thus, in US-A-2,293,716 very small quantities of Cliz+ ions are added as an "accelerator", or as a "colour neutraliser" to improve the whiteness of anodic electrocoating paint. In this connection, it was observed that additions of copper increase the layer weight, in particular on steel.
DE-A-40 13 483 discloses a process for phosphating metal surfaces with the use of phosphating solutions which are substantially free from nickel. Zinc, manganese and small quantities of copper are mentioned as being important constituents of the bath. Furthermore, the concentration of Fe(II) is kept below a maximum value by means of oxygen and/or other equally active oxidising agents. The process is used in particular for the pretreatment of metal surfaces for a subsequent coating, in particular an electrocoating.
EP-A-186 823 discloses strongly acidic phosphating solutions having a pH of 1.8 to 2.5 which contain 7.5 to 75 g/1 of zinc ions, 0.1 to 10 g/1 of hydroxylamine and optionally up to 20 g/1 of manganese ions and 5 to 75 g/1 of nitrate ions. The solutions tolerate an iron content of up to 25 g/1.
EP-A-315 059 discloses a process for the zinc phosphating of iron-containing surfaces. The required morphology of the zinc phosphate crystals is obtained by the use of hydroxylammonium salts, hydroxylamine complexes and/or hydroxylamine.
EP-B-633 950 discloses a process for producing copper-containing nickel-free phosphate layers having a copper content of 0.1 to 5 wt. % and a chain length of the phosphate crystals of 0.5 to 10 ~m on metal surfaces selected from steel, zinc-coated steel, steel coated with zinc alloy, aluminum and alloys thereof, by treating the same in a spraying process, dipping process, or spraying/dipping process using a phosphating solution containing the following components:
zinc ions 0.2 to 2 g/1 copper ions 0.5 to 25 mg/1 phosphate ions 5 to 30 g/1 (calculated as PZOS) and also hydroxylamine salts, hydroxylamine complexes and/or hydroxylamine in a quantity of 500 to 5,000 ppm of hydroxylamine, based on the phosphating solution Phosphating baths which contain hydroxylamine as accelerator and also copper ions have the following disadvantage: the catalytic effect of copper ions leads to an accelerated decomposition of the hydroxylamine. This effect is particularly marked in spraying processes, during which the phosphating solution comes into close contact with air. This catalytic decomposition considerably increases the consumption of hydroxylamine and leads to an increase in the cost of the phosphating process.
An object of the present invention is therefore to provide phosphating solutions wherein the decomposition of hydroxylamine by copper is retarded by the presence of suitable stabilisers.
The present invention accordingly relates to an acidic aqueous phosphating solution containing:
0.3 to 3 g/1 of zinc ions 4 to 30 g/1 of phosphate ions, 0.002 to 0.2 g/1 of copper ions and 0.25 to 10 g/1 of hydroxylamine in free form, as salt or as a hydroxylamine-releasing compound, characterised in that it contains in addition one or more stabilisers for hydroxylamine, selected from organic molecules which have at least two heteroatoms per molecule or, in the case of polymers, at least one heteroatom per four carbon atoms, with at least one of the heteroatoms being a nitrogen atom or an oxygen atom and heteroatoms bonded to the same carbon atom being counted only once and, in the case of carboxyl-containing molecules or of polymers, with there having to be at least three carbon atoms between neighbouring carboxyl groups.
That heteroatoms bonded to the same atom are counted only once means, for example, that the two oxygen atoms of a carboxyl group are counted as only one heteroatom.
Likewise, sulfo groups or phosphonic groups are for this purpose rated as only one heteroatom. The reason for this method of counting is based on the assumption that the stabilising action of organic molecules containing heteroatoms is connected with a complexing action with copper.
However, acidic groups, such as carboxyl groups, for steric reasons generally act only as monodentate ligands, that is, only one oxygen atom is available for a coordination with the copper.
The result of this method of counting is that monocarboxylic acids which have no other heteroatoms apart from the one carboxyl group do not come within the scope of the present invention. They do not develop an adequate stabilising action. The present definition also excludes dicarboxylic, oligocarboxylic or polycarboxylic acids wherein there are not at least three carbon atoms between neighbouring carboxyl groups. Acids having more closely spaced carboxyl groups, owing to the complexing action of the latter with iron, may directly influence the layer formation and lead, for example, to unsuitable layer weights. Only those dicarboxylic, oligocarboxylic or polycarboxylic acids wherein neighbouring carboxyl groups are separated by at least three carbon atoms may be recommended as stabilisers without possibly adverse side effects. For this reason, by way of example, oxalic acid, malic acid, tartaric acid or citric acid, as well as poly(meth)acrylic acids, do not come within the scope of the application.
The stabiliser may, for example, be characterised in that it contains a sequence of atoms X -C,_3 - Y, wherein X represents an oxygen atom or nitrogen atom and Y
represents an oxygen atom, nitrogen atom, phosphorus atom or sulfur atom. Particularly suitable are those stabilisers containing a sequence of atoms O - C - C - O or O - C - C - C - O
wherein, in accordance with the above limitation, at most one of the two O atoms of the above-mentioned sequence of atoms may in this case be part of a carboxyl group. These may in particular be polyethylene glycols, polypropylene glycols or polytetrahydrofuran. Suitable examples are polyethylene glycols having an average molar mass of 200 to 10,000, determined by gel permeation chromatography.
The stabiliser may also be a diazole derivative or triazole derivative.
Examples of such active derivatives are carbendazim and/or 1H-benzotriazole-5-carboxylicacid.
The stabiliser may also be selected from molecules which contain a sequence of atoms - N - C
- C - Y' - Z, wherein Z represents an oxygen atom or a nitrogen atom and Y' represents a carbon atom, sulfur atom or phosphorus atom or may even be completely absent.
For example, this sequence of atoms may be: - N - C - C - N -. Preferred molecules here are those wherein the two nitrogen atoms are members of two aromatic heterocyclic rings.
Included here are in particular 2,2'-bipyridine, 2,2' :6' ,2"-terpyridine and 1,10-phenanthroline.
The stabiliser may also contain the sequence of atoms: - N - C - C - O. These stabilisers may, for example, be alpha amino acids. Preferred amino acids here are those having at least one aromatic group. Examples of these are phenylalanine, tyrosine, tryptophan and histidine.
Also suitable are those molecules containing a sequence of atoms: - N - C - C -O wherein the nitrogen atom is a member of a heterocyclic aromatic ring. For example, the nitrogen atom may be in a pyridine ring. An example of such a compound is picolinic acid.
The phosphating bath may also contain a stabiliser possessing a sequence of atoms - N - C -C
- Y - O, wherein Y represents a sulfur atom or a phosphorus atom. This includes, for example, nitrogen-containing sulfonic acid and phosphonic acid. Here, too, it is advantageous that the stabiliser have a molecular structure wherein the nitrogen atom is a member of a heterocyclic aromatic ring, in particular a pyridine ring. An example of such a heterocyclic sulfonic acid is quinoline-8-sulphonicacid.
Other examples of stabilisers according to the general definition are aromatic hydroxycarboxylic acids. In particular hydroxybenzoic acids having one or more hydroxyl groups may be considered. The p-hydroxybenzoic acid is particularly suitable.
In general the type and quantity of the stabiliser is to be so chosen that it forms no precipitates with copper ions in the concentration range of 0.002 to 0.2 g/1 at the pH of a phosphating solution, which is usually between about 2.5 and about 3.8. It is advisable to accommodate the concentration of the stabiliser to the concentration of the copper ions.
The molar ratio of stabiliser to copper ions should be 1:1 to 20:1. If a polymer, such as a polyglycol, is used as stabiliser, then for the purpose of calculating the concentration the term "mol" refers to the monomer unit. In the case of polyethylene glycol this would be the ethylene oxide unit.
The stabiliser is used particularly for copper-containing zinc phosphating solutions which contain in addition up to 2 g/1 manganese ions.
Phosphating solutions are conventionally prepared by diluting an aqueous concentrate with water to the concentration for use and if necessary adjusting the required pH
or the value of the "free acid" (a generally known term in the field of phosphating) by adding alkalies. The present invention accordingly also includes an aqueous concentrate, which after dilution with water in the ratio of 1:10 to 1:100 and, if necessary, adjustment of the pH, produces a phosphating solution according to one or more of claims 1 to 18.
As components of the phosphating bath are consumed during the phosphating process, it is conventional to adjust the set concentration of these components by continuous or intermittent addition of a replenishing solution. Depending on the differing consumption of the individual components in the phosphating solution, the quantities in the replenishing solution may differ from the quantities to be adjusted in the phosphating bath. For example, the phosphating solution need contain no zinc ions if, during the phosphating of zinc-coated material, owing to acid attack, sufficient zinc ions enter the phosphating bath. If, for example, particularly the consumption or the decomposition of the accelerator hydroxylamine has to be compensated, the replenishing solution may contain a higher ratio of hydroxylamine to layer-forming canons than that in the phosphating bath. In the simplest case, the replenishing solution may contain only hydroxylamine and stabiliser and no layer-forming components. The present invention accordingly also includes an aqueous replenishing solution for a phosphating solution according to one or more of claims 1 to 18, which contains hydroxylamine in free form, as a salt or as a compound releasing hydroxylamine, and also one or more stabilisers, the stabiliser being defined according to at least one of claims 1 to 17.
Examples A commercially available phosphating bath concentrate was prepared by mixing the following components in the order given:
486.40 g/kg water 358.80 g/kg phosphoric acid (75 % ) 31.00 g/kg zinc oxide (99 % ) 35.00 g/kg manganese carbonate (92%) 2.80 g/kg iron (II) sulfate* 7 water 42.00 g/kg fluorosilicic acid (34 % ) 44.00 g/kg hydroxylamine (50 % ) corresponding to 54.55 g hydroxylamine sulfate An operable phosphating bath is obtained by adding a 4.8 wt. % aqueous solution of this concentrate and adjusting to a pH of 3.2. Different quantities of copper ions (as copper sulfate) and stabiliser are added to this phosphating bath, which is then stored at S~C in a drying oven. At particular times, the residual content of hydroxylamine is determined analytically by the so-called "acetone method" . The 1:20 diluted bath solution is ( 1 ) adjusted to a pH of 3.76 using 0.1 N NaOH and 10 ml of acetone is added and is (2) readjusted to pH
3.76 using 0.1 N NaOH. Consumption (2) in ml x 0.033 = % hydroxylamine in the bath. In the Tables below the initial content of hydroxylamine is in each case assigned a relative value of 100 % and the quantities of hydroxylamine found at particular times are stated with reference to this.
Table 1 below shows the residual content of hydroxylamine as a function of the time in storage at 55°C. Here, a Cu concentration of 0.11 mmol/1 corresponding to 7 mg/1, was established for series A and a Cu concentration of 0.16 mmol/1, corresponding to 10.2 mg/1, was established for series B.
In a further series of experiments the accelerated decomposition of hydroxylamine on close contact of the phosphating solution with air, such as occurs during a spraying process, was investigated. To this end a phosphating bath was prepared as described above and 7 mg/1 of copper ions was added thereto. The phosphating bath was heated to S~C. At this temperature, the bath was stirred with a magnetic stirrer sufficiently vigorously for air to be stirred into the bath. At various times, the residual contents of hydroxylamine were determined and stated with reference to a relative initial content of 100 % .
The results are shown in Table 2 below.
Table 1: Residual hydroxylamine content as a function of the time in storage at 55°C
Exp. No. Stabiliser Molar Relative ratio hydroxylamine to Cu content [g]
after Series A: 0.11 mmol/1 copper 0 4 d 7 d 11 14 d d d Comp. 1 none 0 100 70.5 46.8 8.8 0 Exp. 1 Histidine 4 100 76.5 62 14.3 0 Exp. 2 Tyrosine 4 100 69.7 48.6 20.1 0 Exp. 3 Tyrosine 15 100 70.8 53.5 23.8 3.1 Exp. 4 Tryptophan 3 100 72.8 50.8 25.3 0 Exp. 5 Phenylalanine 4 100 73.6 52.2 29.2 0 Exp. 6 Phenylalanine 17 100 73.9 57.3 32.3 0 Exp. 7 EDTA 3 100 72.1 59.4 26.4 0 Exp. 8 p-Hydroxybenzoic 10 100 70 47.8 24.3 0 acid Series B: 0.16 mmol/1 copper 0 4 d 7 d 11 14 d d d Comp. 2 none 0 100 66 43.8 8.2 0 Exp. 9 1,10- 3 100 74.5 55.7 29.2 5.1 phenanthroline Exp. 10 1,10- 6 100 73 51 31.4 5.9 phenanthroline Exp. 11 Quinoline-8- 3 100 70.3 48.5 22.2 0 sulphonic acid Exp. 12 Picolinic acid 4 100 69.5 45.6 21.9 0 Exp. 13 1H-benzotriazole 6 100 74.5 55 24.8 8.9 Exp. 14 2,2':6',2"- 5 100 77.9 61.4 40.5 12.8 terpyridine Exp. 15 2,2'-bipyridine 3 100 73.1 51.2 29.7 2.4 Exp. 16 Tryptophan 5 100 71.8 58.9 22.9 0 Table 2: Residual hvdroxylamine content as a function of time after vigorous stirring at 55°C
Exp. No. Stabiliser Concn. Relative stabiliser hydroxylamine mg/1 content [%]
after 0.11 mmol/1 copper h h h h h Comp. none 100 4.7 0 0 0 Exp. 17 Polyethylene 150 100 72.4 46.3 14.6 0 glycol 600 Exp. 18 Polyethylene 150 100 72.8 45.5 12.9 0 glycol 400 Exp. 19 Polyethylene 150 100 70.8 44.9 12.2 0 glycol 2000 Exp. 20 Polyethylene 100 100 70.1 41.6 13.9 0 glycol 600 Exp. 5 Polyethylene 300 100 72.4 43.7 14.3 0 glycol 600
This invention relates to phosphating solutions suitable for the production of crystalline zinc phosphate layers on steel, zinc-coated steel or steel coated with zinc alloy and also on aluminium and alloys thereof. In addition to zinc ions and phosphate ions, these phosphating solutions contain copper ions and also hydroxylamine in free, salt-like or bound form as accelerator.
The addition of small quantities of copper ions to phosphating baths has already been known for 40 years. Thus, in US-A-2,293,716 very small quantities of Cliz+ ions are added as an "accelerator", or as a "colour neutraliser" to improve the whiteness of anodic electrocoating paint. In this connection, it was observed that additions of copper increase the layer weight, in particular on steel.
DE-A-40 13 483 discloses a process for phosphating metal surfaces with the use of phosphating solutions which are substantially free from nickel. Zinc, manganese and small quantities of copper are mentioned as being important constituents of the bath. Furthermore, the concentration of Fe(II) is kept below a maximum value by means of oxygen and/or other equally active oxidising agents. The process is used in particular for the pretreatment of metal surfaces for a subsequent coating, in particular an electrocoating.
EP-A-186 823 discloses strongly acidic phosphating solutions having a pH of 1.8 to 2.5 which contain 7.5 to 75 g/1 of zinc ions, 0.1 to 10 g/1 of hydroxylamine and optionally up to 20 g/1 of manganese ions and 5 to 75 g/1 of nitrate ions. The solutions tolerate an iron content of up to 25 g/1.
EP-A-315 059 discloses a process for the zinc phosphating of iron-containing surfaces. The required morphology of the zinc phosphate crystals is obtained by the use of hydroxylammonium salts, hydroxylamine complexes and/or hydroxylamine.
EP-B-633 950 discloses a process for producing copper-containing nickel-free phosphate layers having a copper content of 0.1 to 5 wt. % and a chain length of the phosphate crystals of 0.5 to 10 ~m on metal surfaces selected from steel, zinc-coated steel, steel coated with zinc alloy, aluminum and alloys thereof, by treating the same in a spraying process, dipping process, or spraying/dipping process using a phosphating solution containing the following components:
zinc ions 0.2 to 2 g/1 copper ions 0.5 to 25 mg/1 phosphate ions 5 to 30 g/1 (calculated as PZOS) and also hydroxylamine salts, hydroxylamine complexes and/or hydroxylamine in a quantity of 500 to 5,000 ppm of hydroxylamine, based on the phosphating solution Phosphating baths which contain hydroxylamine as accelerator and also copper ions have the following disadvantage: the catalytic effect of copper ions leads to an accelerated decomposition of the hydroxylamine. This effect is particularly marked in spraying processes, during which the phosphating solution comes into close contact with air. This catalytic decomposition considerably increases the consumption of hydroxylamine and leads to an increase in the cost of the phosphating process.
An object of the present invention is therefore to provide phosphating solutions wherein the decomposition of hydroxylamine by copper is retarded by the presence of suitable stabilisers.
The present invention accordingly relates to an acidic aqueous phosphating solution containing:
0.3 to 3 g/1 of zinc ions 4 to 30 g/1 of phosphate ions, 0.002 to 0.2 g/1 of copper ions and 0.25 to 10 g/1 of hydroxylamine in free form, as salt or as a hydroxylamine-releasing compound, characterised in that it contains in addition one or more stabilisers for hydroxylamine, selected from organic molecules which have at least two heteroatoms per molecule or, in the case of polymers, at least one heteroatom per four carbon atoms, with at least one of the heteroatoms being a nitrogen atom or an oxygen atom and heteroatoms bonded to the same carbon atom being counted only once and, in the case of carboxyl-containing molecules or of polymers, with there having to be at least three carbon atoms between neighbouring carboxyl groups.
That heteroatoms bonded to the same atom are counted only once means, for example, that the two oxygen atoms of a carboxyl group are counted as only one heteroatom.
Likewise, sulfo groups or phosphonic groups are for this purpose rated as only one heteroatom. The reason for this method of counting is based on the assumption that the stabilising action of organic molecules containing heteroatoms is connected with a complexing action with copper.
However, acidic groups, such as carboxyl groups, for steric reasons generally act only as monodentate ligands, that is, only one oxygen atom is available for a coordination with the copper.
The result of this method of counting is that monocarboxylic acids which have no other heteroatoms apart from the one carboxyl group do not come within the scope of the present invention. They do not develop an adequate stabilising action. The present definition also excludes dicarboxylic, oligocarboxylic or polycarboxylic acids wherein there are not at least three carbon atoms between neighbouring carboxyl groups. Acids having more closely spaced carboxyl groups, owing to the complexing action of the latter with iron, may directly influence the layer formation and lead, for example, to unsuitable layer weights. Only those dicarboxylic, oligocarboxylic or polycarboxylic acids wherein neighbouring carboxyl groups are separated by at least three carbon atoms may be recommended as stabilisers without possibly adverse side effects. For this reason, by way of example, oxalic acid, malic acid, tartaric acid or citric acid, as well as poly(meth)acrylic acids, do not come within the scope of the application.
The stabiliser may, for example, be characterised in that it contains a sequence of atoms X -C,_3 - Y, wherein X represents an oxygen atom or nitrogen atom and Y
represents an oxygen atom, nitrogen atom, phosphorus atom or sulfur atom. Particularly suitable are those stabilisers containing a sequence of atoms O - C - C - O or O - C - C - C - O
wherein, in accordance with the above limitation, at most one of the two O atoms of the above-mentioned sequence of atoms may in this case be part of a carboxyl group. These may in particular be polyethylene glycols, polypropylene glycols or polytetrahydrofuran. Suitable examples are polyethylene glycols having an average molar mass of 200 to 10,000, determined by gel permeation chromatography.
The stabiliser may also be a diazole derivative or triazole derivative.
Examples of such active derivatives are carbendazim and/or 1H-benzotriazole-5-carboxylicacid.
The stabiliser may also be selected from molecules which contain a sequence of atoms - N - C
- C - Y' - Z, wherein Z represents an oxygen atom or a nitrogen atom and Y' represents a carbon atom, sulfur atom or phosphorus atom or may even be completely absent.
For example, this sequence of atoms may be: - N - C - C - N -. Preferred molecules here are those wherein the two nitrogen atoms are members of two aromatic heterocyclic rings.
Included here are in particular 2,2'-bipyridine, 2,2' :6' ,2"-terpyridine and 1,10-phenanthroline.
The stabiliser may also contain the sequence of atoms: - N - C - C - O. These stabilisers may, for example, be alpha amino acids. Preferred amino acids here are those having at least one aromatic group. Examples of these are phenylalanine, tyrosine, tryptophan and histidine.
Also suitable are those molecules containing a sequence of atoms: - N - C - C -O wherein the nitrogen atom is a member of a heterocyclic aromatic ring. For example, the nitrogen atom may be in a pyridine ring. An example of such a compound is picolinic acid.
The phosphating bath may also contain a stabiliser possessing a sequence of atoms - N - C -C
- Y - O, wherein Y represents a sulfur atom or a phosphorus atom. This includes, for example, nitrogen-containing sulfonic acid and phosphonic acid. Here, too, it is advantageous that the stabiliser have a molecular structure wherein the nitrogen atom is a member of a heterocyclic aromatic ring, in particular a pyridine ring. An example of such a heterocyclic sulfonic acid is quinoline-8-sulphonicacid.
Other examples of stabilisers according to the general definition are aromatic hydroxycarboxylic acids. In particular hydroxybenzoic acids having one or more hydroxyl groups may be considered. The p-hydroxybenzoic acid is particularly suitable.
In general the type and quantity of the stabiliser is to be so chosen that it forms no precipitates with copper ions in the concentration range of 0.002 to 0.2 g/1 at the pH of a phosphating solution, which is usually between about 2.5 and about 3.8. It is advisable to accommodate the concentration of the stabiliser to the concentration of the copper ions.
The molar ratio of stabiliser to copper ions should be 1:1 to 20:1. If a polymer, such as a polyglycol, is used as stabiliser, then for the purpose of calculating the concentration the term "mol" refers to the monomer unit. In the case of polyethylene glycol this would be the ethylene oxide unit.
The stabiliser is used particularly for copper-containing zinc phosphating solutions which contain in addition up to 2 g/1 manganese ions.
Phosphating solutions are conventionally prepared by diluting an aqueous concentrate with water to the concentration for use and if necessary adjusting the required pH
or the value of the "free acid" (a generally known term in the field of phosphating) by adding alkalies. The present invention accordingly also includes an aqueous concentrate, which after dilution with water in the ratio of 1:10 to 1:100 and, if necessary, adjustment of the pH, produces a phosphating solution according to one or more of claims 1 to 18.
As components of the phosphating bath are consumed during the phosphating process, it is conventional to adjust the set concentration of these components by continuous or intermittent addition of a replenishing solution. Depending on the differing consumption of the individual components in the phosphating solution, the quantities in the replenishing solution may differ from the quantities to be adjusted in the phosphating bath. For example, the phosphating solution need contain no zinc ions if, during the phosphating of zinc-coated material, owing to acid attack, sufficient zinc ions enter the phosphating bath. If, for example, particularly the consumption or the decomposition of the accelerator hydroxylamine has to be compensated, the replenishing solution may contain a higher ratio of hydroxylamine to layer-forming canons than that in the phosphating bath. In the simplest case, the replenishing solution may contain only hydroxylamine and stabiliser and no layer-forming components. The present invention accordingly also includes an aqueous replenishing solution for a phosphating solution according to one or more of claims 1 to 18, which contains hydroxylamine in free form, as a salt or as a compound releasing hydroxylamine, and also one or more stabilisers, the stabiliser being defined according to at least one of claims 1 to 17.
Examples A commercially available phosphating bath concentrate was prepared by mixing the following components in the order given:
486.40 g/kg water 358.80 g/kg phosphoric acid (75 % ) 31.00 g/kg zinc oxide (99 % ) 35.00 g/kg manganese carbonate (92%) 2.80 g/kg iron (II) sulfate* 7 water 42.00 g/kg fluorosilicic acid (34 % ) 44.00 g/kg hydroxylamine (50 % ) corresponding to 54.55 g hydroxylamine sulfate An operable phosphating bath is obtained by adding a 4.8 wt. % aqueous solution of this concentrate and adjusting to a pH of 3.2. Different quantities of copper ions (as copper sulfate) and stabiliser are added to this phosphating bath, which is then stored at S~C in a drying oven. At particular times, the residual content of hydroxylamine is determined analytically by the so-called "acetone method" . The 1:20 diluted bath solution is ( 1 ) adjusted to a pH of 3.76 using 0.1 N NaOH and 10 ml of acetone is added and is (2) readjusted to pH
3.76 using 0.1 N NaOH. Consumption (2) in ml x 0.033 = % hydroxylamine in the bath. In the Tables below the initial content of hydroxylamine is in each case assigned a relative value of 100 % and the quantities of hydroxylamine found at particular times are stated with reference to this.
Table 1 below shows the residual content of hydroxylamine as a function of the time in storage at 55°C. Here, a Cu concentration of 0.11 mmol/1 corresponding to 7 mg/1, was established for series A and a Cu concentration of 0.16 mmol/1, corresponding to 10.2 mg/1, was established for series B.
In a further series of experiments the accelerated decomposition of hydroxylamine on close contact of the phosphating solution with air, such as occurs during a spraying process, was investigated. To this end a phosphating bath was prepared as described above and 7 mg/1 of copper ions was added thereto. The phosphating bath was heated to S~C. At this temperature, the bath was stirred with a magnetic stirrer sufficiently vigorously for air to be stirred into the bath. At various times, the residual contents of hydroxylamine were determined and stated with reference to a relative initial content of 100 % .
The results are shown in Table 2 below.
Table 1: Residual hydroxylamine content as a function of the time in storage at 55°C
Exp. No. Stabiliser Molar Relative ratio hydroxylamine to Cu content [g]
after Series A: 0.11 mmol/1 copper 0 4 d 7 d 11 14 d d d Comp. 1 none 0 100 70.5 46.8 8.8 0 Exp. 1 Histidine 4 100 76.5 62 14.3 0 Exp. 2 Tyrosine 4 100 69.7 48.6 20.1 0 Exp. 3 Tyrosine 15 100 70.8 53.5 23.8 3.1 Exp. 4 Tryptophan 3 100 72.8 50.8 25.3 0 Exp. 5 Phenylalanine 4 100 73.6 52.2 29.2 0 Exp. 6 Phenylalanine 17 100 73.9 57.3 32.3 0 Exp. 7 EDTA 3 100 72.1 59.4 26.4 0 Exp. 8 p-Hydroxybenzoic 10 100 70 47.8 24.3 0 acid Series B: 0.16 mmol/1 copper 0 4 d 7 d 11 14 d d d Comp. 2 none 0 100 66 43.8 8.2 0 Exp. 9 1,10- 3 100 74.5 55.7 29.2 5.1 phenanthroline Exp. 10 1,10- 6 100 73 51 31.4 5.9 phenanthroline Exp. 11 Quinoline-8- 3 100 70.3 48.5 22.2 0 sulphonic acid Exp. 12 Picolinic acid 4 100 69.5 45.6 21.9 0 Exp. 13 1H-benzotriazole 6 100 74.5 55 24.8 8.9 Exp. 14 2,2':6',2"- 5 100 77.9 61.4 40.5 12.8 terpyridine Exp. 15 2,2'-bipyridine 3 100 73.1 51.2 29.7 2.4 Exp. 16 Tryptophan 5 100 71.8 58.9 22.9 0 Table 2: Residual hvdroxylamine content as a function of time after vigorous stirring at 55°C
Exp. No. Stabiliser Concn. Relative stabiliser hydroxylamine mg/1 content [%]
after 0.11 mmol/1 copper h h h h h Comp. none 100 4.7 0 0 0 Exp. 17 Polyethylene 150 100 72.4 46.3 14.6 0 glycol 600 Exp. 18 Polyethylene 150 100 72.8 45.5 12.9 0 glycol 400 Exp. 19 Polyethylene 150 100 70.8 44.9 12.2 0 glycol 2000 Exp. 20 Polyethylene 100 100 70.1 41.6 13.9 0 glycol 600 Exp. 5 Polyethylene 300 100 72.4 43.7 14.3 0 glycol 600
Claims (26)
1. Use of organic molecules which have at least two hetero atoms per molecule or in the case of polymers at least one hetero atom per 4 carbon atoms, wherein at least one of the hetero atoms is a nitrogen atom or an oxygen atom and hetero atoms bonded to the same C atom being counted only once and, in the case of carboxyl-containing molecules or polymers, with there having to be at least three C atoms between two neighbouring carboxyl groups, as stabilisers for hydroxylamine in acidic, aqueous phosphating solutions containing 0.3 to 3 g/l of zinc ions 4 to 30 g/l of phosphate ions, 0.002 to 0.2 g/l of copper ions and 0.25 to 10 g/l of hydroxylamine in free form as salt or as a hydroxylamine-releasing compound.
2. Use according to claim 1, wherein the stabiliser contains a sequence of atoms X-C1-3-Y, wherein X represents an oxygen atom or nitrogen atom and Y represents an oxygen atom, nitrogen atom, phosphorus atom or sulfur atom.
3. Use according to claim 2, wherein the stabiliser contains a sequence of atoms O-C-C-O or O-C-C-C-O, with at most one of the oxygen atoms of the sequence of atoms being part of a carboxyl group.
4. Use according to claim 3, wherein the stabiliser is polyethylene glycol, polypropylene glycol or polytetrahydrofuran.
5. Use according to claim 1, wherein the stabiliser is a diazole derivative or triazole derivative.
6. Use according to claim 5, wherein the stabiliser is carbendazim and/or 1H-benzotriazole-5-carboxylicacid.
7. Use according to claim 2, wherein the stabiliser is selected from molecules which contain a sequence of atoms -N-C-C-Y'-Z, wherein Z represents an oxygen atom or a nitrogen atom and Y' represents a carbon atom, sulphur atom or phosphorus atom or may even be completely absent.
8. Use according to claim 7, wherein the stabiliser contains a sequence of atoms -N-C-C-N-.
9. Use according to claim 8, wherein the two nitrogen atoms are members of two aromatic heterocyclic rings.
10. Use according to claim 9, wherein the stabilisers are selected from 2,2'-bipyridine, 2,2':6',2"-terpyridine and 1,10-phenanthroline.
11. Use according to claim 7, wherein the stabiliser contains a sequence of atoms -N-C-C-O.
12. Use according to claim 11, wherein the stabiliser is an alpha-amino acid.
13. Use according to claim 12, wherein the amino acid has at least one aromatic group.
14. Use according to claim 11, wherein the nitrogen atom is a member of a heterocyclic aromatic ring.
15. Use according to claim 7, wherein the stabiliser contains a sequence of atoms -N-C-C-Y-O, wherein Y denotes a sulfur atom or a phosphorus atom.
16. Use according to claim 15, wherein the nitrogen atom is a member of a heterocyclic aromatic ring.
17. Use according to claim 1, wherein the stabiliser is selected from hydroxybenzoic acids.
18. Use according to one or more of claims 1 to 17, wherein the phosphating solution contains the stabiliser in quantities of from one mol of stabiliser (in polymers: mol based on monomer units) to 20 mol of stabiliser per mol of copper ions.
19. Use of an aqueous concentrate for the preparation of a phosphating solution, wherein the said concentrate, after dilution with water in the ratio of 1:10 to 1:100 and, if necessary, adjustment of the pH value, produces a phosphating solution corresponding to the definition in one or more of claims 1 to 18.
20. Use of an aqueous solution for replenishing a phosphating solution which is to contain 0.3 to 3 g/l of zinc ions 4 to 30 g/l of phosphate ions, 0.002 to 0.2 g/l of copper ions and 0.25 to 10 g/l of hydroxylamine in free form as salt or as a hydroxylamine-releasing compound as well as a stabiliser for hydroxylamine, wherein the replenishing solution contains hydroxylamine in free form, as a salt or as a compound releasing hydroxylamine, and also one or more stabilisers corresponding to the definition in at least one of claims 1 to 17.
21. Acidic, aqueous phosphating solution which contains 0.3 to 3 g/l of zinc ions 4 to 30 g/l of phosphate ions, 0.002 to 0.2 g/l of copper ions and 0.25 to 10 g/l of hydroxylamine in free form as salt or as a hydroxylamine-releasing compound, wherein it contains in addition one or more stabilisers for hydroxylamine, selected from:
a) polyethylene glycol, polypropylene glycol or polytetrahydrofuran, b) diazole derivatives or triazole derivatives, c) molecules containing a sequence of atoms -N-C-C-Y-Z, wherein Z represents an oxygen atom or a nitrogen atom and Y represents a sulphur atom or a phosphorus atom, d) molecules which contain a sequence of atoms -N-C-C-N-, wherein the two nitrogen atoms are members of two aromatic heterocyclic rings, e) alpha-amino acids, f) molecules containing a sequence of atoms -N-C-C-O, wherein the nitrogen atom is a member of a heterocyclic aromatic ring, g) hydroxybenzoic acids.
a) polyethylene glycol, polypropylene glycol or polytetrahydrofuran, b) diazole derivatives or triazole derivatives, c) molecules containing a sequence of atoms -N-C-C-Y-Z, wherein Z represents an oxygen atom or a nitrogen atom and Y represents a sulphur atom or a phosphorus atom, d) molecules which contain a sequence of atoms -N-C-C-N-, wherein the two nitrogen atoms are members of two aromatic heterocyclic rings, e) alpha-amino acids, f) molecules containing a sequence of atoms -N-C-C-O, wherein the nitrogen atom is a member of a heterocyclic aromatic ring, g) hydroxybenzoic acids.
22. Phosphating solution according to claim 21, wherein the stabiliser specified under b) is carbendazim or 1H-benzotriazole-5-carboxylicacid.
23. Phosphating solution according to claim 21, wherein the stabiliser specified under c) is selected from molecules which contain a sequence of atoms -N-C-C-Y-O, wherein Y denotes a sulfur atom or a phosphorus atom and the nitrogen atom is a member of a heterocyclic aromatic ring.
24. Phosphating solution according to claim 21, wherein the stabiliser specified under d) is selected from 2,2'-bipyridine,2,2':6',2"-terpyridine and 1,10-phenanthroline.
25. Phosphating solution according to one or more of claims 21 to 24, wherein it contains the stabiliser in quantities of from one mol of stabiliser (in polymers: mol based on monomer units) to 20 mol of stabiliser per mol of copper ions.
26. Aqueous concentrate for the preparation of a phosphating solution, wherein the said concentrate, after dilution with water in the ratio of 1:10 to 1:100 and, if necessary, adjustment of the pH value, produces a phosphating solution corresponding to the definition in one or more of claims 21 to 25.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19700326.5 | 1997-01-08 | ||
| DE1997100326 DE19700326A1 (en) | 1997-01-08 | 1997-01-08 | Stabilizers for hydroxylamine in copper-containing phosphating solutions |
| PCT/EP1997/007185 WO1998030732A1 (en) | 1997-01-08 | 1997-12-19 | Hydroxylamine stabilizers in copper-containing phosphating solutions |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2277336A1 true CA2277336A1 (en) | 1998-07-16 |
Family
ID=7816929
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002277336A Abandoned CA2277336A1 (en) | 1997-01-08 | 1997-12-19 | Stabilizers for hydroxylamine in copper-containing phosphating solution |
Country Status (8)
| Country | Link |
|---|---|
| EP (1) | EP0960220A1 (en) |
| JP (1) | JP2002500702A (en) |
| AU (1) | AU5859098A (en) |
| BR (1) | BR9714199A (en) |
| CA (1) | CA2277336A1 (en) |
| DE (1) | DE19700326A1 (en) |
| TR (1) | TR199901460T2 (en) |
| WO (1) | WO1998030732A1 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| RU2691443C2 (en) | 2014-04-30 | 2019-06-13 | Рио Фервальтунгс Аг | Processing device and processing method for etching and phosphating of metal parts |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS57179843A (en) * | 1981-04-30 | 1982-11-05 | Oriental Shashin Kogyo Kk | Color developer composition for color photographic sensitive silver halide material |
| JPS595574B2 (en) * | 1981-10-20 | 1984-02-06 | 日進化工株式会社 | Hydroxylamine stabilizer |
| JPS595573B2 (en) * | 1981-10-20 | 1984-02-06 | 日進化工株式会社 | Hydroxylamine stabilizer |
| JPS59160142A (en) * | 1983-03-02 | 1984-09-10 | Fuji Photo Film Co Ltd | Method for processing color photosensitive silver halide material |
| JPH068956B2 (en) * | 1983-04-04 | 1994-02-02 | 富士写真フイルム株式会社 | Processing method of silver halide color photosensitive material |
| US4975357A (en) * | 1989-05-23 | 1990-12-04 | Eastman Kodak Company | Method of photographic color development using polyhydroxy compounds, metal ions and sequestering agents |
| DE4210513A1 (en) * | 1992-03-31 | 1993-10-07 | Henkel Kgaa | Nickel-free phosphating process |
| IT1274594B (en) * | 1994-08-05 | 1997-07-18 | Itb Srl | ACID WATER PHOSPHATIC SOLUTION AND METALLIC SURFACE PHOSPHATION PROCESS USING IT |
| DE19606017A1 (en) * | 1996-02-19 | 1997-08-21 | Henkel Kgaa | Zinc phosphating with low copper and manganese contents |
-
1997
- 1997-01-08 DE DE1997100326 patent/DE19700326A1/en not_active Withdrawn
- 1997-12-19 EP EP97954444A patent/EP0960220A1/en not_active Withdrawn
- 1997-12-19 CA CA002277336A patent/CA2277336A1/en not_active Abandoned
- 1997-12-19 JP JP53050498A patent/JP2002500702A/en active Pending
- 1997-12-19 AU AU58590/98A patent/AU5859098A/en not_active Abandoned
- 1997-12-19 BR BR9714199-2A patent/BR9714199A/en unknown
- 1997-12-19 TR TR1999/01460T patent/TR199901460T2/en unknown
- 1997-12-19 WO PCT/EP1997/007185 patent/WO1998030732A1/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| DE19700326A1 (en) | 1998-07-09 |
| TR199901460T2 (en) | 1999-11-22 |
| AU5859098A (en) | 1998-08-03 |
| BR9714199A (en) | 2000-03-28 |
| WO1998030732A1 (en) | 1998-07-16 |
| JP2002500702A (en) | 2002-01-08 |
| EP0960220A1 (en) | 1999-12-01 |
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