JP2001515959A - Pretreatment of painting of composite metal structures with aluminum parts - Google Patents

Abstract

  (57) [Summary] In a chemical pre-treatment process prior to painting of a composite metal structure having steel, galvanized steel and / or alloy-plated steel parts and aluminum or aluminum alloy parts, the steel and galvanized steel or alloy The metal structure is treated with a zinc phosphate chemical conversion solution that forms a crystalline zinc phosphate film on the surface of the gold-plated steel, but does not form a zinc phosphate film on the surface of the aluminum part. The metal structure is brought into contact with a treatment solution that forms a chemical conversion layer on the surface of the aluminum part without excessively dissolving the crystalline zinc phosphate film on the surface of the steel, galvanized steel and / or alloy-plated steel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[Background Art]

The use of aluminum in vehicle structures is increasing for a number of reasons, such as weight, stiffness, and recyclability. In the description of the present invention, the term "aluminum"
It includes not only pure aluminum but also aluminum alloys whose main component is aluminum. Examples of commonly used alloying elements are silicon, magnesium, copper, manganese, chromium, and nickel, and the weight ratio of all these alloying elements is usually 10% or less.

[0002] A large amount of aluminum is already used for engines, gear parts, wheels, seat frames, and the like. However, use of aluminum in a vehicle body structure is not limited to a hood, a rear trunk, an inner part of a door, various small parts and a truck. Cabs, vehicle cab side walls or minivan accessories. Overall, less than 5% of the metal surfaces of automobile bodies are made of aluminum worldwide. Research into increasing the use of aluminum in this area is being actively pursued in the aluminum and automotive industries.

[0003] The present invention relates to an anticorrosion pretreatment process prior to painting of a composite metal structure having parts of aluminum and / or aluminum alloy in addition to parts of steel and / or galvanized steel. This process is intended especially for use in automobile manufacturing. In the manufacture of automobiles, car bodies or body parts having components of aluminum and / or aluminum alloy in addition to components of steel and / or galvanized steel are subjected to a conversion pre-treatment before being painted. chemical pretreatment
) Is applied. In this regard, the first stage of painting is now cathodic dip coating (
cathodic electro-dip-coating) is commonly used. The process of the present invention is particularly suited to this stage of pretreatment.

[0004] The process of the present invention is a conventional step in automotive manufacturing in that in the first step, a zinc phosphate layer is formed on the steel and / or galvanized steel surface with little coating on the aluminum surface. Different from the processing process. The second step comprises treatment with a solution that does not excessively erode the previously formed layer of zinc phosphate, but preferably enhances its anticorrosive action, while at the same time forming a surface layer on the aluminum surface.

[0005] Thus, the first stage involves a two-stage process having a conventional zinc phosphate conversion treatment. Of course, it is a necessary condition to use a zinc phosphate chemical conversion treatment solution that does not form a layer on the surface of aluminum. Such zinc phosphate conversion treatment solutions are known in the prior art and are mentioned below by way of example. In the second step, a solution containing a component effective for forming a protective layer on the aluminum surface is used. The properties and concentrations of this solution ensure that, on the one hand, a layer is formed on the surface of the aluminum, while on the other hand steel and / or
Alternatively, it must be selected so that the layer of crystalline zinc phosphate formed on the galvanized steel surface is not excessively damaged.

[0006] The purpose of phosphating a metal is to create a layer of metal phosphate that is firmly attached to the metal surface, which itself increases the corrosion resistance and is compatible with paints or other organic coatings. This contributes to a significant improvement in the adhesion of the film and the creep resistance under corrosive stress. Such a phosphatization process has been known for a long time. As a pretreatment for coating, particularly for electrolytic dip coating, the zinc ion concentration in the phosphating solution is relatively low, for example, 0.5 to 2 g / L (hereinafter generally referred to as "g / L"). A process using a zinc-concentrated phosphatization solution is particularly suitable. The basic parameters of this low zinc concentration phosphate conversion bath are
The weight ratio of phosphate ions to zinc ions is usually larger than 8 and may reach 30.

It is known that the simultaneous use of polyvalent cations in a zinc phosphate treatment bath enables the formation of a phosphate layer with significantly improved corrosion protection and paint adhesion. For example, a low zinc concentration process in which 0.5 to 1.5 g / L of manganese ions and 0.3 to 2.0 g / L of nickel ions are added is a so-called trication process, which is used for painting, for example, cathodic electrolysis of an automobile body. Widely used for conditioning metal surfaces in dip coating.

[0008] Nickel and cobalt are now both as poisonous and detrimental from the point of view of wastewater treatment, so they are now as efficient as the tricationic process and have significantly lower nickel and / or cobalt concentrations. Efforts are being made to find a phosphatization process that does not use these two metals.

[0009] EP-A-459541 contains substantially no nickel, and contains 0.2 to 4 g / L of manganese and 1 to 30 mg / L (hereinafter referred to as "m") in addition to zinc and phosphoric acid.
g / L ") of copper phosphate. DE-A-
No. 4,210,513, a nickel-free phosphate chemical conversion treatment solution containing 0.5 to 25 mg / L of copper ions in addition to zinc and phosphoric acid and hydroxylamine as an accelerator is known. This treatment liquid may also contain 0.15 to 5 g / L of manganese.

[0010] German Patent Application DE 196 01 60.76 describes a phosphoric acid with a reduced heavy metal concentration comprising 0.2 to 3 g / L of zinc ions, 1 to 150 mg / L of manganese ions and 1 to 30 mg / L of copper ions. A chemical conversion solution is described. This treatment liquid may contain up to 50 mg / L of nickel ions and up to 100 mg / L of cobalt ions. Further, it may contain 0.2 to 1.5 g / L of lithium ions.

DE 195 38 778 describes the use of hydroxylamine as an accelerator to control the coverage of the phosphate layer. The use of hydroxylamine and / or its compounds to affect the formation of phosphate crystals is known in many literatures. EP-A-315059 discloses a special effect of the use of hydroxylamine in a phosphatizing bath, where the zinc concentration in the bath exceeds the normal range of low zinc concentration processes, it can be columnar or nodular. (No
discloses that phosphate crystals of the desired shape form on the steel surface. In this case, the zinc concentration is up to 2 g / L and the weight ratio of phosphoric acid to zinc is 3.7.
And low phosphating baths. The required concentration of hydroxylamine is 0.5-50 g / L, preferably 1-10 g / L.

WO93 / 03198 states that the zinc concentration is 0.5-2 g / L, the nickel and manganese concentrations are 0.2-1.5 g / L, respectively, and the weight ratio of zinc to other divalent cations It is disclosed that hydroxylamine is used as an accelerator in a tricationic phosphating bath where is maintained at a predetermined value. The bath also contains 1 to 2.5 g / L of "hydroxylamine accelerator", which has been shown to be a salt of hydroxylamine, preferably hydroxylamine ammonium sulfate.

In order to improve the anticorrosion performance of the phosphate layer, a so-called post-inactivation cleaning (pa
ssivating post-rinsing or post-passivation) is commonly used in this technology. For this purpose, treatment baths containing chromic acid are still widely used. However, from the viewpoint of work safety and environmental protection, it is a general tendency to replace the chromium-containing inactivation bath with a chromium-free treatment bath.

For this purpose, organic reactive bath solutions containing complex-substituted poly (vinylphenol) are known. Examples of such compounds are described in DE-C-3146265. Particularly useful polymers of this type include amine substitutes and poly (
(Vinylphenol) and aldehydes and organic amines. Such polymers are, for example, EP-B-91166, EP-B-319
016 and EP-B-319017. Such polymers are also used in the present invention, and the contents of the four immediately preceding references are mentioned here, except to the extent that they contradict the obvious facts of the present invention. The use of such a polyvinyl phenol derivative for the surface treatment of aluminum is described in, for example, the above-mentioned EP-B-3190.
16 known.

WO 90/12902 has a pH in the range of about 2.5 to about 5.0 and, in addition to a derivative of polyvinyl phenol, phosphate ions and zircon, titanium, hafnium and silicon fluoro acids. A chromium-free coating of aluminum is disclosed, wherein the aluminum surface is contacted with a processing solution containing the same.

US Pat. No. 5,129,967 describes a non-cleaning treatment of aluminum (“dried in place”).
Conversion baths) are disclosed, which include the following: (a) a copolymer of polyacrylic acid or acrylic acid at 10 to 16 g / L; (b) hexafluorozirconic acid at 12 to 19 g / L; (c) hydrofluoric acid at 0.17 to 0.3 g / L; d) hexafluorotitanic acid of 0.6 g / L or less.

[0017] EP-B-8942 discloses a treatment solution suitable for aluminum cans having a pH of less than 3.5, including: (a) 0.5 to 10 g / polyacrylic acid or an ester thereof (b) of the L 0.2~8g / L of the compound _{H 2 ZrF 6, H 2 TiF} 6 and one or more of H ₂ SiF _6. It also discloses a replenisher for replenishing a processing solution, including: (a) 25~100g / polyacrylic acid or an ester thereof (b) of the L 25~100g / L of the compound _{H 2 ZrF 6, H 22 TiF} 6 and one or more of _{H 2 SiF 6 (c) 17~120g} / A fluoride ion source that produces L free fluoride.

DE-C-193 33013 contains 0.1 to 15 g / L of complex fluorides of boron, titanium or zircon, whose pH is above 3.5 and whose stoichiometric equivalent is properly measured. And a treatment bath containing 0.5 to 30 g / L of an oxidizing agent, particularly sodium meta-nitrobenzenesulfonate. DE-C-2433704 discloses 0.1 to 5 g / L of polyacrylic acid or a salt or ester thereof, especially as a treatment bath for improving paint adhesion and long-term corrosion resistance on aluminum surfaces.
including processing bath fluorozirconate ammonium 0.1~3.5g / L in terms of and rO ₂ is disclosed. The pH of this bath can be varied over a wide range. Generally, best results are obtained when the pH is between 6 and 8.

US Pat. No. 4,992,116 discloses an aluminum conversion treatment bath having a pH value of about 2.5 to 5 and containing at least the following three components. (a) 1.1 × 10 ^{−5 to} 5.3 × 10 ⁻³ mol / liter phosphate ion (corresponding to 1 to 500 mg / L); (b) 1.1 × 10 ^{−5 to} 1.3 × 10 ⁻³ mole / L of Zr, Ti, Hf and Si in one group (corresponding to 1.6 to 380 mg / L of each element) fluoro acid; and (c) 0.26 to 20 g / L is a polyphenol compound obtained by reacting poly (vinylphenol) with an aldehyde and an organic amine. The molar ratio of fluoroacid to phosphate must be maintained between about 2.5: 1 to about 1:10. There is.

[0020] DE-A-2715292 discloses that titanium and / or zircon in which the parts by weight (hereinafter referred to as “ppm”) per million are 10 or more, phosphates in the range of 10 to 1000 ppm, and titanium and / or Also disclosed is a chromium-free pretreatment bath for an aluminum can having a pH value of 1.5 to 4 containing a sufficient amount of fluoride (but not less than 13 ppm) to produce zircon and complex fluoride. ing.

[0021] WO 92/07973 is used as an essential component in an acidic aqueous solution, from 0.01 to about 1%.
Using up to 8 wt% H ₂ ZrF ₆ and from 0.01 to about 10 wt% 3- (NC _1-4 alkyl-N-2-hydroxyethyl-aminomethyl) -4-hydroxystyrene polymer. A chromium-free aluminum treatment process is disclosed. As an optional component, 0.05 to 10% by weight of dispersed SiO ₂ , and 0.06 to 0.6% by weight of a polymer dissolving agent or a surfactant may be contained. The above-mentioned polymers are included in the "reaction product of poly (vinylphenol) with an aldehyde and an amine containing an organic hydroxyl group", which is also used in the present invention described later.

It is known that simultaneous phosphatization of the surface of aluminum and the surface of steel and / or galvanized steel requires a technical compromise in the composition of the treatment bath. Aluminum ions released from the aluminum surface by etching or pickling act as harmful components of the phosphatization solution and inhibit the formation of zinc phosphate crystals on the iron surface. Therefore, the dissolved aluminum must be precipitated or masked by appropriate means. For this purpose, usually free or complex-bound fluoride ions are added to the phosphating bath.

Fluoride ions can be converted to aluminum ions by formation of complex compounds and / or, if the concentration exceeds the solubility product of the corresponding salt, by precipitation as sodium and / or potassium hexafluoroaluminates. Is masked. Furthermore, the released fluoride ions usually increase the erosion due to the etching of the aluminum surface, so that they are more or less closed and sealed.
and sealed) A layer of zinc phosphate is formed on the surface.

The simultaneous phosphatization of aluminum components with steel and / or galvanized steel components thus has the disadvantage that the chemical conversion bath must be monitored very accurately for fluoride concentration. Have a special point. This increases the amount of control and monitoring work and also necessitates the storage and metering of separate fluoride solutions as replenishers. In addition, the precipitated hexafluoroaluminate increases the amount of phosphatized sludge and increases the cost of its removal and disposal.

Thus, in composite structures having parts of steel and / or galvanized steel in addition to aluminum parts, such as the body of a motor vehicle, there is a need for a pre-treatment process. It is necessary to expand the range of phosphatization solutions and reduce control and monitoring tasks. As a result of the overall pre-treatment, all exposed metal surfaces must be provided with a suitable conversion layer as a corrosion protection coating.

[0026]

DISCLOSURE OF THE INVENTION

The purpose of this is a chemical pretreatment process prior to the organic coating of a composite metal structure having parts of aluminum and / or aluminum alloy, together with parts of steel, galvanized steel and / or alloy plated steel, comprising: Achieved by a characteristic process.

That is, (I) In the first step, a crystalline zinc phosphate film having an adhesion amount of 0.5 to 5 g / m ² is formed on the surface of steel, galvanized steel and / or alloy-plated steel. Then, the composite metal structure is treated with a zinc phosphate conversion treatment solution that does not form a zinc phosphate film on the surface of the aluminum portion.

Then, with or without intermediate washing with water, (II) In the second step, the crystals formed in step (I) on the surface of steel, galvanized steel and / or alloy-plated steel Preferably does not dissolve more than 60, 50, 40, 30, 20, 15, 10, 8 or 6% of the zinc phosphate coating, respectively, and the surface of the aluminum portion This is a process of bringing the composite metal structure into contact with a treatment solution for forming a chemical conversion layer.

In step (I), the provision that no zinc phosphate film is formed on the surface of the aluminum portion means that a closed and sealed crystal layer is not formed, and It should be understood that the mass per unit area does not exceed 0.5 g / m ² (hereinafter referred to as “g / m ² ”) in any part of the aluminum portion. In order to satisfy this condition, the phosphatization bath can be arbitrarily determined as long as specific conditions are maintained for the fluoride concentration.

This condition is shown in EP-B-452638. This document outlines the conditions under which a closed zinc phosphate layer is formed on an aluminum surface.
According to the disclosure, it is necessary to satisfy the condition that the concentration of released fluoride ions at a certain temperature T (expressed in ° C.) exceeds 8 / T, expressed in g / L.
However, in the present invention, in contrast to the teaching of EP-B-452638, in the phosphating step (I), a certain temperature T (° C.) It is necessary that the concentration (g / L) of the released fluoride ions in the phosphatization solution in (display) is less than 8 / T.

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION

That is, in step (I), the zinc phosphate chemical conversion treatment solution is about 2.5 to about 3.
A free fluoride concentration in g / L of 8 / T (T is the liquid temperature in ° C.) having a pH in the range of up to 6 and a temperature in the range of about 20 to about 65 ° C. It is preferable to use one that does not exceed the value of ()).

The zinc phosphate chemical conversion treatment liquid preferably contains the following components independently of each other. 0.3 to 3 g / L of Zn (II), 5 to 40 g / L of phosphate ion, and one or more of the following accelerators in the following amounts 0.3 to 4, more preferably 1 to 4 g / L of chlorine Acid ion, 0.01-0.2 g / L nitrite ion, 0.05-2, more preferably 0.2-2 g / l m-nitrobenzenesulfonate ion, 0.05-2 g / L m-nitrobenzoate ion, 0.05-2 g / l p-nitrophenol, 0.001-0.15, more preferably 0.001-0.070 g / l free or bound hydrogen peroxide, 0 0.1 to 10 g / l of free or bound hydroxyamine, and 0.1 to 10 g / l of reducing sugar.

In the case where the zinc phosphate chemical conversion treatment liquid in step (I) further contains one or more cations having the following concentrations, the crystalline zinc phosphate formed in such a phosphate chemical conversion treatment bath It is empirically known that the corrosion resistance and paint adhesion of the film are improved. 0.001-4 g / l Mn (II), 0.001-4 g / l Ni (II), 0.002-0.2 g / l Cu (II), 0.2-2.5 g / l Mg (II), 0.2-2.5 g / l Ca (II), 0.01-0.5 g / l Fe (II), 0.2-1.5 g / l Li (I) And W (VI) from 0.02 to 0.8 g / l.

[0034] More preferably, the zinc concentration is in the range of about 0.8 to about 1.6 g / L. A zinc concentration above 1.6 g / L, for example 2-3 g / L, would not be very advantageous for the process, but could increase sludge production in the phosphating tank. If zinc dissolves into the treatment bath by etching during the phosphate conversion treatment of the galvanized steel surface, the zinc concentration in the phosphating bath is adjusted during the operation. About 1 to 50 mg / L for nickel and about 5 to 100 mg / L for cobalt
The nickel and / or cobalt ions in the concentration range are combined with the nitrate concentration being as low as possible, below about 0.5 g / L, when the phosphating bath does not contain nickel or cobalt or when the nitrate concentration is zero. More than 0.5 g / L, the anticorrosion property and paint adhesion are improved. In this way, a favorable compromise can be found between the performance of the phosphatization bath and the requirements from the wastewater treatment of the wash water.

For a phosphatization bath with a low heavy metal content, the manganese concentration is about 0.5.
It may be in the range of 001 to 0.2 g / L. Otherwise, about 0.5-1.
A manganese concentration of 5 g / L is common.

From DE-A-19500927 it is known that lithium ions in an amount of about 0.2 to about 1.5 g / L improve the anticorrosion performance obtained with a zinc phosphate conversion bath. Lithium at a concentration of 0.2 to about 1.5 g / L, especially about 0.4 to about 1 g / L, has a beneficial effect on the anti-corrosion performance resulting from the phosphatization process of the present invention and the subsequent treatment. Effect.

Apart from the above-mentioned cations which are incorporated into the zinc phosphate layer or which advantageously influence the crystal growth thereof, the phosphatization baths also contain, in principle, sodium, potassium and / or Or contains an ammonium ion. The term "free acid" is well known to those skilled in the art of phosphatization. A method for determining the free and total acids in this step is given in the examples.
Free acid and total acid are important control parameters in the phosphatization because they have a great influence on the coating amount. The free acidity ranges from 0 to 1.5 points in the phosphating treatment of parts and 2.5 points in the coil treatment, and the total acidity is about 10 points (preferably about 10 points in the immersion chemical treatment). 15 points) to about 30 points fall within the normal technical range, and this range is appropriate in the present invention.

In the phosphate conversion treatment of the zinc surface, it is not always necessary that the treatment bath contains a so-called accelerator. However, in the phosphatization of steel surfaces, it is necessary that the treatment bath contains one or more accelerators. Such an accelerator has been conventionally used as a component of a zinc phosphate chemical conversion treatment bath. The term accelerator refers to a substance that chemically reacts with the hydrogen generated on the metal surface by the etching action of the acid. Further, the oxidizing accelerator has an effect of oxidizing Fe (II) ions released by the etching action on the steel surface to trivalent and precipitating them as phosphates of Fe (III).

In the step (II), it is also possible to use a conventional solution for forming a conversion layer on the aluminum surface. However, this solution
The crystalline zinc phosphate layer formed in step (I) must not be excessively dissolved.
Therefore, the pH of this solution is preferably in the range of 2.5-10, more preferably 3.3-10. As advantageous in step (II), a solution containing a component that makes the crystalline zinc phosphate layer more inert is selected. Such solutions are mentioned below by way of example. In the process of the present invention, in order to contact the metal structure with the treatment solution in the step (II), a spray method or an immersion method is usually used. The temperature of the processing solution in step (II) is preferably selected in the range of 20 to 70 ° C.

For example, the treatment solution of step (II) has a pH in the range of about 5 to about 5.5,
Those containing a total of about 0.3 to about 1.5 g / L of hexafluorotitanate and / or hexafluorozirconate ions may be used. If the solution of step (II) further contains about 0.01-0.1 g / L of copper ions, step (I)
May be advantageous for the anticorrosion property of the crystalline zinc phosphate layer formed by the method.

Further, in step (II), having a pH in the range of 3.5-5.8,
A treatment solution containing 00 mg / L of an organic polymer selected from poly-4-vinylphenol compounds represented by the following general formula (I) may be used.

[0042]

Embedded image

Here, n is an integer between 5 and 100, and each of X and Y independently represents a hydrogen group or a CRR ¹ OH group, and each of R and R ¹ in this group is independently hydrogen. A group or an aliphatic or aromatic group having 1 to 12 carbon atoms.

According to EP-B-319016, it is particularly preferable to use a treatment solution containing a derivative of polyvinylphenol in step (II). This reference also discloses the preparation of such polyvinylphenol derivatives. Therefore, in the step (II), it has a pH in the range of 3.3 to 5.8 and the following substance (α
) And (β), a treatment solution containing 10 to 5000 mg / L of an organic polymer selected from a homopolymer (homopolymar) or a copolymer compound containing an amino group, having one or more polymers selected from (β). Preferably, it is used. Here, the substance (α) is composed of a polymer molecule having at least one unit represented by the following general formula (II).

[0045]

Embedded image

Each of R ^{2 to} R ⁴ is independently of each other, independently of each other, or independently of each other when one or more units represented by the above formula are present in one polymer molecule. A hydrogen group, an alkyl group having 1 to 5 carbon atoms and an allyl group having 6 to 18 carbon atoms.

Each of Y ^{1 to} Y ⁴ is independently of each other, independently of each other, or independently of each other when two or more units represented by the above formula are present in one polymer molecule. A hydrogen group, a —CH ₂ Cl group, an alkyl group having 1 to 18 carbon atoms, an allyl group having 6 to 18 carbon atoms, represented by the general formula —CR ¹² R ¹³ OR ¹⁴ Selected from the group consisting of

Each of R ^{12 to} R ¹⁴ is a hydrogen group, an alkyl group, an allyl group, a hydroxyalkyl group, an aminoalkyl group, a mercaptoalkyl group, a phosphoalkyl group, or one of the following two general formulas It is selected from the group consisting of Z groups.

[0049]

Embedded image

Here, each of R ^{5 to} R ⁸ independently of one another, independently of each other,
When there are two or more units represented by the above formula in the polymer molecule, each of the units independently represents a hydrogen group, an alkyl group, an allyl group, a hydroxyalkyl group, an aminoalkyl group, a mercaptoalkyl group and a phosphoalkyl group. Selected from the group consisting of
And R ⁹ is selected from a hydrogen group, an alkyl group, an allyl group, a hydroxy or polyhydroxyalkyl group, an amino or polyaminoalkyl group, a mercapto or polymercaptoalkyl group, a phospho or polyphosphoalkyl group, a -0 ^- group and an -OH group. Selected from the group

At least one of Y ¹ to Y ^{4 in} at least one unit of each of the selected polymer molecules is a Z group defined by the above formula, and W ¹ is independently between each constituent molecule. And when two or more units represented by the general formula (II) are present in one polymer molecule, a hydrogen group, an acyl group, an acetyl group, a benzoyl group; Hydroxypropyl group; 3-benzyloxy-2-hydroxypropyl group; 3-butoxy-2-hydroxypropyl group; 3-alkyloxy-2-hydroxypropyl group; 2-hydroxyoctyl group; 2-hydroxyalkyl group; -Hydroxy-2-phenylethyl group; 2-hydroxy-2-alkylphenylethyl group; benzyl, methyl, ethyl, propyl, unsubstituted alkyl, unsubstituted allyl, Substituted alkylbenzyl; halo or polyhaloalkyl, or halo or polyhaloalkenyl groups; groups derived from condensation polymerization products that remove one hydrogen atom from ethylene oxide, propylene oxide or mixtures thereof; and sodium, potassium, lithium , Ammonium or substituted ammonium, or a phosphonium or substituted phosphonium cationic group.

In addition, the substance (β) does not include the unit represented by the general formula (II), and includes an organic polymer including one or more units corresponding to the following general formula (III).

[0053]

Embedded image

Here, each of R ¹⁰ and R ¹¹ is independent of each other, independently of each other, and when each polymer molecule contains two or more units represented by the above formula, Independently of each other, a hydrogen group, an alkyl group having 1 to 5 carbon atoms and 6 to 18 carbon atoms
Is selected from the group consisting of

Each of Y ^{4 to} Y ⁶ is independently of each other, independently of each constituent molecule, and independently of each other when two or more units represented by the above formula are present in one polymer molecule. ,
Except as described below, a hydrogen group, a —CH ₂ Cl group, an alkyl group having 1 to 18 carbon atoms, an allyl group having 6 to 18 carbon atoms, and a group represented by the general formula —CR ¹² R ¹³ OR ¹⁴ Selected from the group R ^{12 to} R ¹⁴ each represent a hydrogen group, an alkyl group, an allyl group, a hydroxyalkyl group, an aminoalkyl group, a mercaptoalkyl group, a phosphoalkyl group and a substance.
(Α) is selected from the group consisting of the Z groups defined above.

One or more of Y ¹ to Y ⁴ in at least one unit of each selected polymer molecule is a Z group as defined above, and W ² is independently represented by 1 When there are two or more units represented by the above formula in the polymer molecule, hydrogen, acyl, acetyl, benzoyl, 3-allyloxy-2-hydroxypropyl, 3-benzyl Oxy-2-hydroxypropyl group, 3-butoxy-2-hydroxypropyl group, 3-alkyloxy-2-hydroxypropyl group, 2-hydroxyoctyl group, 2-hydroxyalkyl group, 2-hydroxy-2-phenylethyl Group, 2-hydroxy-2-alkylphenylethyl group, benzyl, methyl, ethyl, propyl, unsubstituted alkyl, unsubstituted allyl, unsubstituted Rukirubenjiru, halo or polyhalo alkyl, or halo or poly haloalkenyl group, ethylene oxide, propylene oxide or a hydrogen atom from a mixture thereof 1
Selected from the group consisting of a group derived from the condensation polymerization product from which the cations are removed, and a cationic group of sodium, potassium, lithium, ammonium or substituted ammonium or phosphonium or substituted phosphonium.

The term “polymer molecule” in the above definition of substances (α) and (β) includes any electrically neutral molecule having a molecular weight of 300 (Dalton) or more.

Mainly for economic reasons, the substances (α) and / or (β) usually have the units of the general formulas (I) and (II), except where the terminal groups are relatively short. It is desirable to mainly use a molecule consisting of one of the above. Similarly, for economic reasons, such materials generally comprise homopolymers of p-vinylphenol for substance (α) and phenol-aldehyde condensation products for substance (β), formaldehyde and secondary It is prepared by reacting with a tertiary amine and joining a Z group to the activated benzene ring.

However, in certain cases, substances (α) and / or (β) with more complex chemical structures
May be more useful. For example, the component (α
) Or a condensable form of molecule belonging to (β) (except where the requirement that the molecule has one or more Z groups is not initially required) is a phenol, tannin, novolak-type resin, lignin compound, A condensation product is prepared by reacting with a different molecule selected from the group consisting of aldehydes, ketones and mixtures thereof, and if necessary,
This is further reacted with (1) an aldehyde or ketone, and (2) a secondary amine,
One or more previously defined Z groups may be introduced into each molecule such that the molecule is a substance (α) or (β).

Another example of a more complex material used as material (α) is that the polymer chain is entirely or mainly composed of unsubstituted or substituted 4-vinylphenol and a vinyl monomer such as Is a substance comprising a copolymer of This vinyl monomer includes acrylonitrile, methacrylonitrile, methyl acrylate, methyl methacrylate, vinyl acetate, vinyl methyl ketone, isopropenyl methyl ketone, acrylic acid, methacrylic acid, acrylamide, methacrylamide, n -amyl methacrylate, styrene , m - bromostyrene, p - bromostyrene, pyridine, diallyldimethylammonium salts, 1,3-butadiene, n -
Butyl acrylate, t -butylaminoethyl methacrylate, n -butyl methacrylate, t -butyl methacrylate, n -butyl vinyl ether, t -butyl vinyl ether, m -chlorostyrene, o -chlorostyrene, p -chlorostyrene, n -decyl methacrylate, N, N-diallylmelamine, N, N-di- n -butylacrylamide, di- n -butylitaconate, di- n -butylmaleate, diethylaminoethyl methacrylate, diethylene glycol monovinyl ether, diethyl fumarate, diethyl itaconate, Diethyl vinyl phosphate, vinyl phosphate, diisobutyl maleate, diisopropyl itaconate, diisopropyl maleate, dimethyl fumarate, dimethyl itaconate, Rumareeto, di - n - Nonirufumareto, di - n - Nonirumareeto, dioctyl fumarate, di - n - octyl itaconate, di - n - propyl itaconate, N- dodecyl vinyl ether, acidic ethyl fumarate, acidic ethyl maleate, ethyl Acrylate, ethyl cinnamate, N-ethyl methacrylamide, ethyl methacrylate, ethyl vinyl ether, 5-ethyl-2-vinylpyridine, 5-ethyl-2-vinylpyridine-1-oxide, glycidyl acrylate, glycidyl methacrylate, n -hexyl methacrylate , 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, isobutyl methacrylate, isobutyl vinyl ether, isoprene, isopropyl methacrylate, iso Propyl vinyl ether, itaconic acid, lauryl methacrylate, methacrylamide, methacrylic acid, methacrylonitrile, N-methylolacrylamide, N-methylolmethacrylamide, N-isobutoxymethylacrylamide, N-isobutoxymethylmethacrylamide, N-alkyl Oxymethylacrylamide, N-alkyloxymethylmethacrylamide, N-vinylcaprolactam, methyl acrylate, N-methylmethacrylamide, α-methylstyrene, m -methylstyrene, o -methylstyrene, p -methylstyrene,
2-methyl-5-vinylpyridine, n -propyl methacrylate, sodium p -styrenesulfonate, stearyl methacrylate, styrene, p -styrenesulfonic acid, p -styrenesulfonamide, vinyl bromide, 4-vinylcarbazole, Vinyl chloride, vinylidene chloride, 1-vinylnaphthalene, 2
-Vinylnaphthalene, 2-vinylpyridine, 4-vinylpyridine, 2-vinylpyridine N-oxide, 4-vinylpyrimidine and N-vinylpyrrolidone.

The following considerations apply to the molecules of the substances (α) and (β) as preferred choices, independently of each other, mainly for reasons of improved economy, improved corrosion protection and / or increased water solubility.

Each of R ^{2 to} R ⁵ , R ¹⁰ , R ¹¹ , W ¹ and W ² independently of each other and independently of each other in the same or different molecule, preferably a hydrogen group Each of Y ^{1 to} Y ⁶ independently of each other and independently of each unit in the same or different molecule, preferably a hydrogen group or a Z group; the above-mentioned general formula ( The number of units corresponding to one of II) and (III) is preferably (more preferably later) 2, 3, 4, 5, 6, 7 or 8 or more, and independently of this: It is preferably 100, 75, 50, 40, 30, or 20 or less.

The ratio of the number of Z groups to the number of aromatic nuclei in the substances (α) and (β) in the composition of the present invention used in the step (II) is preferably (the later the better, the better). More preferably) 0.01: 1.0, 0.03: 1.0, 0.05: 1.0, 0.10: 1.0, 0.20: 1.0, 0.40: 1.0 , 0.50: 1.0, 0.60: 1.0, 0.70: 1.0, 0.80: 1.0, 0.90: 1.0 or 0.95: 1.0 or more And, independently of this, preferably (more preferably later) 2.0: 1.0, 1.6: 1.0, 1.50: 1.0, 1.40: 1.0 1.30: 1. 0, 1.20: 1.0, 1.10: 1.0 or 1.00: 1.0 or less.

The total of the substances (α) and (β) in the composition of the present invention used in the step (II) is a “polyoxy Z group” based on the total number of Z groups in the composition. One or more of R ^{5 to} R ⁸ in the general formula is (i) 3 to 8, preferably 4 to 6 carbon atoms, and (ii) one or more R ^{5 to} R ⁸ , each of which is bonded to a carbon atom. The ratio of the numbers (defined as Z groups having fewer hydroxy groups than the number of carbon atoms in the group) is preferably (more preferably later) 0.10: 1.0, 0.20: 1.0, 0.30: 1.0, 0.40: 1.0, 0.50: 1.0, 0. 60: 1.0, 0.70: 1.0, 0.80: 1.0, 0.90: 1.0 or 0.98: 1.0 or more.

Poly (5-vinyl-2-hydroxy-N-benzyl) -N-methylglucamine is the most preferred type of polymer, which at least in its acidic pH range to be ensured Some exist as ammonium salts.

A solution containing no active ingredient other than the polyvinylphenol derivative and an acid (preferably phosphoric acid) for adjusting the pH may be used. However, the addition of active ingredients, in particular hexafluorotitanate or hexafluorozirconate ions, in addition to this may improve the layer formation on the aluminum surface. For example, the pH is preferably in the range of about 3.3 to 5.8, 10 to 2000 mg / L phosphate, 10 to 2500 mg / L hexafluorotitanate or hexafluorozirconate and 10 to 1000 mg / L. A solution containing about 100 to about 5000 mg / L of an organic polymer in the form of a methylmethanolamine derivative or a methylglucamine derivative of polyvinylphenol in addition to / Mg of manganese ions may be used.

Instead of a polyvinylphenol derivative, which requires considerable cost for its preparation, a solution or dispersion of an organic polymer selected from homopolymers and / or copolymers of acrylic acid, methacrylic acid and esters thereof is prepared. It may be used in (II). These solutions or dispersions preferably have a pH value in the range from about 3.3 to about 4.8 and contain from about 250 to about 1500 mg / L of the organic polymer. According to EP-B-008942, a solution or dispersion of such a polymer may further comprise hexafluorotitanate, hexafluorozirconate and / or hexafluorosilicate.

[0068]

【Example】

The process of the present invention includes a cold-rolled steel sheet (hereinafter referred to as “CRS”), an electrogalvanized steel sheet (hereinafter referred to as “ZE”), an iron-zinc electroplated steel sheet (hereinafter referred to as “ZFE”), and aluminum. Tested on 6111 sample metal plate. These metal plates were first washed with alkali and activated with an activating liquid containing titanium phosphate, as is customary in the field of automobile manufacturing. Then, the metal plate was heated at a temperature of 48.
It was immersed in a phosphate chemical conversion treatment solution having the following composition at 3 ° C. for 3 minutes.

Zn = 1.2 g / L Mn = 0.8 g / L Ni = 0.8 g / L PO 43 ⁻ = 18 g / L NO 2 ⁻ = 110 ppm Residual cation = Na ⁺ free acid = 1.1.

By this phosphate conversion treatment, a sealed phosphate layer having an adhesion amount of about 2 g / m ² was deposited on the surface of the cold-rolled steel sheet, the electrogalvanized steel sheet, and the iron-zinc electroplated steel sheet. . In the scanning electron micrograph, only widely dispersed zinc phosphate crystals were formed on the aluminum surface.

As step (II), the sample plate was treated with sufficiently deionized water (comparative test) and a solution having one of the following compositions (a), (b) and (c). Solution temperature is 2
Sprayed on sample plate at 5 ° C. for 30 seconds. Then add one to these sheets
After spraying sufficiently deionized water for 5 seconds for 15 seconds, compressed air at room temperature was blown. In order to be used for anticorrosion tests, test plates were coated in a triple coating structure in the following order.
E-coat = PPG ED 5000, base coat = Dupont white 542 AB 839
, Clear coat = Dupont RK 8010. The corrosion resistance test consists of the following steps,
Performed according to the General Motors GMP9540P-B process cycle.

1. (1.1) Spray the spray solution (containing 0.9 wt% sodium chloride, 0.1 wt% calcium chloride and 0.25 wt% sodium bicarbonate, balance water) until each panel is completely wetted, 1.2) Within 30 minutes after spraying, put each panel in an atmosphere at 25 ° C and a relative humidity of 30 to 50%, and (1.3) 9 hours from the start of step (1.2).
Remove it after keeping it in the adjusted atmosphere for 0 minutes, and then follow steps (1.1) and (1.2)
Is repeated three times. Thus, the entire step 1 takes 8 hours. 2. Water condensation test at 49 ° C., 95-100% relative humidity for 8 hours 3. Dry storage for 8 hours at 60 ° C., <30% relative humidity On weekends, dry storage at 25 ° C., 30-50% relative humidity In any case, steps 1 to 3 above form a cycle that is repeated from Monday to Friday. Step 4 is not counted in the number of cycles. The test lasts 40 cycles (5 cycles per week, 8 week test period). Table 1 below shows the compositions of the three post-rinse solutions, and Tables 2 and 3 show the etch amount of the zinc phosphate coating and the average point of the paint at full scribe width, respectively. Indicates creepages.

[0073]

[Table 1] Composition of Post-Rinse

[0074]

[Table 2] Amount of etching loss of zinc phosphate film

[0075]

[Table 3] Corrosion test results

──────────────────────────────────────────────────続 き Continuation of front page (81) Designated country EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE ), OA (BF, BJ, CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, GM, KE, LS, MW, SD, SZ, UG, ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AL, AM, AT, AU, AZ, BA, BB, BG, BR, BY, CA, CH, CN, CU, CZ, DE, DK, EE, ES, FI, GB, GE, GH, GM, HR, HU, ID, IL, IS, JP, KE, KG, KP , KR, KZ, LC, LK, LR, LS, LT, LU, LV, MD, MG, MK, MN, MW, MX, NO, NZ, PL, PT, RO, RU, SD, SE, SG, SI, SK, SL, TJ, TM, TR, TT, UA, UG, US, UZ, VN, YU, ZW. 72) Inventor Göke Jürgen, Germany, D-40225 Düsseldorf, Stofferdam 108 (72) Inventor Enke Forkhard, Germany, D-51 381 Revelksen, Brugroch 14 (72) Inventor Blower Jean Willem, Germany, D- 47877 Willich, Klefelderstrasse 221 (72) Inventor Wensshot Hubert D75180 Forzheim, Ambaldstrasse 19 Fter, Germany 4D075 BB75Y DA06 DB02 DB07 EB01 4K026 AA02 AA07 AA09 AA12 AA25 BA04 BB06 BB08 CA13 CA18 CA23 CA28 CA32 CA34 CA35 CA37 CA39 DA12 DA13 DA15

Claims (13)

[Claims] A chemical pretreatment process prior to the organic coating of a composite metal structure having one or more steel, galvanized steel or alloy-plated steel portions and one or more aluminum or aluminum alloy portions. (I) A crystalline zinc phosphate film having a coating weight of 0.5 to 5 g / m ² is formed on the surface of steel, galvanized steel and alloy-plated steel, but a zinc phosphate film is formed on the surface of the aluminum portion. A first step of treating the composite metal structure with a zinc phosphate conversion treatment solution that does not form, and then, with or without intermediate washing with water, (II) steel, galvanized steel And / or contacting the composite metal structure with a treatment solution that does not dissolve more than 60% of the crystalline zinc phosphate coating on the surface of the alloy-plated steel and forms a conversion layer on the surface of the aluminum part. Step Chemical pretreatment processes that have and. 2. The zinc phosphate chemical conversion treatment solution in step (I) is 2.5 to 3.6.
And a temperature in the range of 20-65 ° C., expressed in g / L,
Contains free fluoride in an amount not exceeding the quotient divided by the liquid temperature in degrees Celsius, and in step (II), the treatment solution comprises 25% of the crystalline zinc phosphate coating formed in step (I). 2. The process of claim 1, wherein the process does not dissolve the super. 3. A zinc phosphate chemical conversion treatment solution used in step (I) comprises: 0.3 to 3 g / L of Zn (II); 5 to 40 g / L of phosphate ions; 0.3 to 4 g / L chlorate ion, 0.01 to 0.2 g / L nitrite ion, 0.05 to 2 g / L m-nitrobenzene sulfonate ion, 0.05-2 g / L m-nitrobenzoate ion, 0.05-2 g / L p-nitrophenol, 0.001-0.15 g / L free or bound hydrogen peroxide, 0.1-10 g / L of hydroxylamine in a free or bound state, and 0.1 to 10 g / L of reducing sugar, and in step (II), the treatment solution is formed of the crystalline zinc phosphate film formed in step (I). 3. The process of claim 2, wherein said process does not dissolve more than 10%. 4. The process according to claim 3, wherein the zinc phosphate conversion solution used in step (I) further comprises one or more of the following amounts of cations. 0.001 to 4 g / L Mn (II), 0.001 to 4 g / L Ni (II), 0.002 to 0.2 g / L Cu (II), 0.2 to 2.5 g / L Mg (II), 0.2-2.5 g / L Ca (II), 0.01-0.5 g / L Fe (II), 0.2-1.5 g / L Li (I) , And 0.02-0.8 g / L of W (VI) 5. The treatment solution used in step (II) has a pH in the range of 3.5 to 5.5, and has a hexafluorotitanate ion of 0.3 to 1.5 g / L. 5. A composition comprising a fluorozirconate ion or both.
The process according to any of the above. 6. The treatment solution used in step (II) may further comprise 0.01 to 0.
. The process according to claim 5, comprising 1 g / L of copper ions. 7. The poly-4-vinylphenol molecule having a pH in the range of 3.5 to 5.8, wherein the treatment solution used in step (II) has a pH in the range of 3.5 to 5.8. An organic polymer selected from the group consisting of 10 to 500 mg / L.
The process according to any of the above. Embedded image Here, n is an integer between 5 and 100, and each of X and Y independently represents a hydrogen group or a CRR ¹ OH group, and each of R and R ¹¹ in this group independently represents a hydrogen group or It is an aliphatic or aromatic group having 1 to 12 carbon atoms. 8. The treatment solution used in step (II) has a pH in the range of 3.3 to 5.8, and comprises an organic polymer selected from the following substances (α) and (β): The process according to any one of claims 1 to 4, comprising 10 to 5000 mg / L. Here, the substance (α) is composed of a polymer molecule having at least one unit represented by the following general formula (II). Embedded image Here, each of R ^{2 to} R ⁴ is independently of each other, independently of each other, and 1
When two or more units represented by the above formula are present in the polymer molecule, a group consisting of a hydrogen group, an alkyl group having 1 to 5 carbon atoms and an allyl group having 6 to 18 carbon atoms is independently formed between the units. Selected from. Each of Y ^{1 to} Y ⁴ is independently of each other, independently of each constituent molecule, and independently of each other when two or more units represented by the above formula are present in one polymer molecule. Excluding the case where they are formed from a hydrogen group, a —CH ₂ Cl group, an alkyl group having 1 to 18 carbon atoms, an allyl group having 6 to 18 carbon atoms, and a group represented by the general formula —CR ¹² R ¹³ OR ¹⁴ Selected from the group. Here, each of R ^{12 to} R ¹⁴ is a hydrogen group, an alkyl group, an allyl group, a hydroxyalkyl group, an aminoalkyl group, a mercaptoalkyl group, a phosphoalkyl group, or one of the following two general formulas. It is selected from the group consisting of Z groups. Embedded image Here, each of R ^{5 to} R ⁸ is independently of each other, independently of each constituent molecule, and independently of each other when two or more units represented by the above formula are present in one polymer molecule. Selected from the group consisting of a hydrogen group, an alkyl group, an allyl group, a hydroxyalkyl group, an aminoalkyl group, a mercaptoalkyl group and a phosphoalkyl group.
And R ⁹ is a hydrogen group, an alkyl group, an allyl group, hydroxy or polyhydroxy Shiarukiru group, amino or polyamino alkyl groups, mercapto or poly mercaptoalkyl group, phospho or poly phosphonium alkyl group, -0 ^- group and
Selected from the group consisting of -OH groups. At least one of Y ¹ to Y ^{4 in} at least one unit of each of the selected polymer molecules is a Z group defined by the above formula, and W ¹ is independently represented by 1 When two or more units represented by the general formula (II) are present in a polymer molecule, a hydrogen group, an acyl group, an acetyl group, an acetyl group, a benzoyl group, a 3-allyloxy-2-hydroxypropyl group is independently provided between the units. 3-benzyloxy-2-hydroxypropyl group, 3-butoxy-2-hydroxypropyl group, 3-alkyloxy-2-hydroxypropyl group, 2-hydroxyoctyl group, 2-hydroxyalkyl group, 2-hydroxy- 2-phenylethyl group, 2-hydroxy-2-alkylphenylethyl group, benzyl, methyl, ethyl, propyl, unsubstituted alkyl, unsubstituted allyl, unsubstituted alkyl Benzyl, halo or polyhaloalkyl or halo or poly haloalkenyl group, ethylene oxide, propylene oxide or a hydrogen atom from a mixture thereof 1
Selected from the group consisting of a group derived from the condensation polymerization product from which the cations are removed, and a cationic group of sodium, potassium, lithium, ammonium or substituted ammonium or phosphonium or substituted phosphonium. The substance (β) does not contain the unit represented by the general formula (II), and has the following general formula
It consists of an organic polymer containing one or more units corresponding to (III). Embedded image Here, each of R ¹⁰ and R ¹¹ is independently of each other, independently of each constituent molecule, and independently of each other when two or more units represented by the above formula are present in one polymer molecule. A hydrogen group, an alkyl group having 1 to 5 carbon atoms and 6 to 18 carbon atoms.
Is selected from the group consisting of Each of Y ^{4 to} Y ⁶ independently of each other, independently of each other, and independently of each other when two or more units represented by the above formula are present in one polymer molecule;
Except as described below, a hydrogen group, a —CH ₂ Cl group, an alkyl group having 1 to 18 carbon atoms, an allyl group having 6 to 18 carbon atoms, and a group represented by the general formula —CR ¹² R ¹³ OR ¹⁴ Selected from the group Here, each of R ^{12 to} R ¹⁴ represents a hydrogen group, an alkyl group, an allyl group, a hydroxyalkyl group, an aminoalkyl group, a mercaptoalkyl group, a phosphoalkyl group, and a Z group defined above for the substance (α). Selected from the group consisting of One or more of Y ¹ to Y ⁴ in at least one unit of each selected polymer molecule is a Z group as defined above, and W ² is independently between each constituent molecule and in one polymer molecule. In the case where there are two or more units represented by the above formula, a hydrogen group, an acyl group, an acetyl group, a benzoyl group, a 3-allyloxy-2-hydroxypropyl group, a 3-benzyloxy-2 -Hydroxypropyl group, 3-butoxy-2-hydroxypropyl group, 3-alkyloxy-2-hydroxypropyl group, 2-hydroxyoctyl group, 2-hydroxyalkyl group, 2-hydroxy-2-phenylethyl group, 2 -Hydroxy-2-alkylphenylethyl group, benzyl, methyl, ethyl, propyl, unsubstituted alkyl, unsubstituted allyl, unsubstituted alkylben Le, halo or polyhalo alkyl, or halo or poly haloalkenyl group, ethylene oxide, propylene oxide or a hydrogen atom from a mixture thereof 1
Selected from the group consisting of a group derived from the condensation polymerization product from which the cations are removed, and a cationic group of sodium, potassium, lithium, ammonium or substituted ammonium or phosphonium or substituted phosphonium. The term "polymer molecule" in the above definition for substances (α) and (β) is intended to include any electrically neutral molecule having a molecular weight of 300 (Daltons) or more. 9. The process according to claim 8, wherein at least 20% by number of Z groups in the substance (α) and the substance (β) in the processing solution used in the step (II) are polyhydroxyl Z groups. 10. The treatment solution used in the step (II), wherein the substance (α) is (i) polyvinylphenol having a weight average molecular weight in the range of 1,000 to 10,000, (ii) formaldehyde or 9. The process of claim 8, comprising a condensation reaction product of paraformaldehyde and (iii) one or more secondary organic amines. 11. The method according to claim 1, wherein said secondary organic amine is selected from the group consisting of methylethanolamine, N-methylglucamine and mixtures thereof.
0 described process. 12. The treatment solution according to claim 1, wherein said treatment solution has a pH in the range of 3.3 to 4.8.
0 to 5000 mg / L of the above condensation reaction product, 10 to 2000 mg / L of phosphate ion, 10 to 2500 mg / L of hexafluorotitanate ion, hexafluorozirconate ion or both thereof, 10 to 1000 mg 12. The process of claim 11, comprising / L of manganese ions. 13. The treatment solution used in step (II) has a pH in the range of 3.3 to 5.8, and is a homopolymer or copolymer of acrylic acid, methacrylic acid and their esters. An organic polymer selected from the group consisting of
The process according to any one of claims 1 to 4, containing 0 mg / L.