JPH09291371A - Resin chromate composition and surface treated metallic sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin chromate composition excellent in bare corrosion resistance at a worked part, resistance to chromium elusion and resistance to fingerprint and to provide a metallic sheet treated with the resin chromate. SOLUTION: In this resin chromate composition, (a) an aq. soln. and/or a water dispersion of a polyester resin containing >=30mol% arom. dicarboxylic acid out of total acid component, (b) a water soluble chromium compd., (c) more than one kind mineral acid and (d) a colloidal silica are incorporated, and the surface treated metallic sheet has a film of the resin chromate composition on the metallic sheet in 5-300mg/m<2> in terms of a metallic chromium.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to metals such as cold rolled steel,
Zn-plated steel sheet, Zn-based alloy-plated steel sheet, Ni, Cu,
A resin chromate composition which forms a resin chromate film by coating and drying on a surface of a metal plated steel sheet of Pb, Sn, Cd, Al, Ti or the like or an alloy plated steel sheet of these metals, and a surface-treated metal having a resin chromate film It is about boards.

[0002]

2. Description of the Related Art Cold rolled steel sheet, Zn plated steel sheet, Zn-Ni
System, Zn-Ni-Co system, Zn-Ni-Cr system, Zn-
Zn-based alloy plated steel sheets such as Fe-based, Zn-Co-based, Zn-Cr-based, Zn-Mn-based, or Ni, Cu, Pb,
In order to improve the corrosion resistance of metal-plated steel sheets such as Sn, Cd, Al, and Ti or alloy-plated steel sheets of these metals, chromate treatment is generally performed to form a chromate film. This chromate treatment can be roughly divided into electrolytic chromate and coating chromate. As the electrochromic chromate, for example, chromic acid as a main component and sulfuric acid added thereto (Japanese Patent Publication No. 39-7).
No. 461), with phosphoric acid added (Japanese Patent Publication No. 30-
No. 3514, Japanese Patent Publication No. 35-8917, Japanese Patent Publication No. 36-9559, Japanese Patent Publication No. 36-9560), and boric acid added (US Pat. No. 2,733,319).
9, U.S. Pat. No. 2,780,592), those to which halogen ions are added (Japanese Patent Publication No. 39-14363), and the like.
It is known to subject a steel sheet to cathodic electrolysis using a bath containing various anions.

As the coating type chromate, one coating a water-soluble chromium compound containing trivalent chromium as a main component, an inorganic colloidal compound and an acidic aqueous solution containing an inorganic anion (JP-A-63-218279), hexavalent chromium. In which colloidal silica is mixed with chromic acid obtained by reducing a part of trivalent chromium (JP-A-63-243279), a water-soluble chromium compound containing trivalent chromium as a main component,
One that treats a liquid containing an inorganic colloidal compound and an inorganic anion (JP-A-63-218279), one that treats a liquid in which a chromic acid of a specific element and a specific proportion of a colloidal compound and an inorganic anion are mixed 63-17
No. 8873), a treatment with a liquid containing chromic acid and an inorganic colloid and an inorganic anion in which the ratio of hexavalent chromium to trivalent chromium is specified, and trivalent chromium in the total chromium containing SiO ₂ and PO ₄ ^3-. Which treats an aqueous chromic acid solution having a specified ratio (Japanese Patent Application Laid-Open No. 1-65272), which contains a specific amount of trivalent chromium ions, and a specific amount of silicofluoride and fluoride with respect to hexavalent and trivalent chromium ions. For treating a liquid containing each sodium salt of JP-A-1-56879
Gazette) Hexavalent and 3 containing a specific amount of trivalent chromium ions
Treating an aqueous solution containing a specific amount of SiO ₂ with respect to valent chromium ions (JP-A-1-56877) Specific for hexavalent and trivalent chromium ions containing a specific amount of trivalent chromium ions A solution obtained by treating a liquid containing an amount of ammonium silicofluoride and a silane coupling agent (JP-A-1-56878), containing chromium and a silica sol in a specific ratio, and specifying a hexavalent chromium amount and a silica sol particle size. What is to be treated (JP-A-2-104672), what contains a specific proportion of chromium ions, phosphoric acid and silicic acid sol, and is to treat a liquid in which hexavalent chromium ions in all chromium ions are specified (JP-A-2-104672) No. 2-85372), chromic acid, an anhydrous colloidal compound, and a solution containing a silane coupling agent in a specific ratio are treated (Japanese Patent Laid-Open No. HEI 3)
No. 146676), a liquid containing silica gel, phosphoric acid and Zn is treated with hexavalent and trivalent chromium ions containing a specific amount of trivalent chromium ions (Japanese Patent Laid-Open No. 3-67883). Etc. can be mentioned.

Also, although it is a kind of coating type chromate,
A coating type chromate to which an organic resin is added, that is, a so-called resin chromate has been recently developed. For example, a treatment method comprising specified chromium, amorphous silica, a phosphoric acid compound, and polyacrylic acid, and specifying the C / Si ratio of the outermost layer of the film (JP-A-2-163385), methyl methacrylate in a chromate solution. A method of adding an acrylic emulsion of a copolymer such as the above under specific conditions and treating it (JP-A-2-179883), a liquid containing chromic acid, a chromic acid reduction product, an acrylic emulsion, and silica sol under specific conditions. Coating method (Japanese Patent Laid-Open No. 3-215683)
No.), chromic acid, a chromic acid reduction product, an acrylic emulsion, and a wet type silica sol under a specific condition (JP-A-3-215681), an ethylenically unsaturated carboxylic acid component, and a hydroxyl group-containing group. For metal surface treatment by mixing monomer component, other aqueous emulsion consisting of ethylenically unsaturated compound, water-soluble chromium compound, water-based colloid of inorganic compound and inorganic substance which reacts with amphoteric metal to form sparingly water-soluble salt Examples thereof include a composition (JP-A-5-230666).

However, among the chromate films formed by electrolysis, although the chromium elution is not small, the corrosion resistance cannot be said to be sufficient, and the scratch resistance of the film during processing is poor, and therefore the corrosion resistance after processing is low. Extremely low.

Further, since the chromate film formed by the coating type has a considerable amount of hexavalent chromium in the film,
Hexavalent chromium repairs the scratches on the chromate film and cracks on the film or metal plating produced by working, so that relatively good corrosion resistance can be obtained by the so-called repair effect. However, the corrosion resistance is not necessary and sufficient, and hexavalent chromium elutes during use, which is not preferable from the viewpoint of environmental hygiene, and there is a strong demand for reduction of chromium elution amount. Further, the fingerprint resistance is also poor, and improvement is desired.

[0007]

On the other hand, various resin chromates have been investigated for the purpose of suppressing the chromium elution amount. In each case, although the chromium elution amount can be suppressed, the corrosion resistance of the processed part is poor. In particular, cracks are generated in the plating layer during processing, which causes a marked failure in a base material having poor workability such as a hot-dip galvanized steel sheet. The reason for this has not been fully clarified, but in the resin chromate, the chromium elution is suppressed by the added organic component, so that the effect of repairing hexavalent chromium as in the case of coating type chromate cannot be obtained. Thought to be one. For this reason, there has been no resin chromate film capable of ensuring corrosion resistance in the processed part.

[0008]

SUMMARY OF THE INVENTION In view of these problems, the inventors of the present invention have both corrosion resistance and chromium elution resistance of the machined part,
Further, as a result of diligent studies of a resin chromate composition imparting fingerprint resistance, an aqueous solution and / or water dispersion of a polyester resin in which an acid component obtained by copolymerizing a hydrophilic component is 30 mol% or more of an aromatic dicarboxylic acid and water-soluble chromium The present invention has been accomplished by discovering that a resin chromate composition containing a compound and one or more kinds of mineral acids as main components is excellent in chromium elution resistance and fingerprint resistance, and surprisingly has a high degree of corrosion resistance in a processed part. .

That is, according to the present invention, (a) an aqueous solution and / or an aqueous dispersion of a polyester resin having an aromatic dicarboxylic acid content of 30 mol% or more of all acid components, (b) a water-soluble chromium compound, and (c) A resin chromate composition comprising one or more kinds of mineral acids and optionally (d) colloidal silica. Furthermore, a film obtained from the above resin chromate composition on a metal plate such as a steel plate, zinc or zinc alloy plated steel plate, aluminum or aluminum alloy plated steel plate, lead or lead alloy plated steel plate, tin or tin alloy plated steel plate. The surface-treated steel sheet has a metal chromium content of 5 to 300 mg / m ² .

The polyester resin (a) used in the present invention has an aromatic dicarboxylic acid (including a hydrophilic group-containing aromatic dicarboxylic acid such as a metal sulfonate group) as an acid component.
It is necessary to copolymerize 30 mol% or more, preferably 40 mol% or more of the total acid component. If the amount of the aromatic dicarboxylic acid is less than 30 mol%, the elution resistance of chromium and the fingerprint resistance are deteriorated. As the aromatic dicarboxylic acid containing no hydrophilic group,
For example, terephthalic acid, isophthalic acid, orthophthalic acid,
1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4′-diphenyldicarboxylic acid,
2,2'-diphenyldicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid and the like can be mentioned. this house,
Particularly, terephthalic acid and isophthalic acid are preferable, and the repeating unit obtained from these acid components and ethylene glycol, for example, is stable even in the presence of mineral acid or chromic acid. As the other dicarboxylic acid, an aliphatic dicarboxylic acid or an alicyclic dicarboxylic acid may be copolymerized. As the alicyclic dicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid,
1,4-cyclohexanedicarboxylic acid, 4-methylhexahydrophthalic anhydride, 3-methylhexahydrophthalic anhydride, 2-methylhexahydrophthalic anhydride, dicarboxyhydrogenated bisphenol A, dicarboxyhydrogenated bisphenol S, hydrogen Examples thereof include added dimer acid, hydrogenated naphthalene dicarboxylic acid, and the like, and aliphatic dicarboxylic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, dodecanedioic acid, azelaic acid, dimer acid and the like. Of these, 1,4-cyclohexanedicarboxylic acid is particularly preferable as the alicyclic dicarboxylic acid, and sebacic acid and azelaic acid are particularly preferable as the aliphatic dicarboxylic acid. Further, a polyvalent carboxylic acid such as trimellitic anhydride or pyromellitic dianhydride may be used in combination as long as the content of the invention is not impaired.

The (a) polyester resin used in the present invention is an anionic hydrophilic group such as a sulfonate group, a sulfate ester salt or a carboxylate salt, a cationic hydrophilic group such as quaternary nitrogen or quaternary phosphorus, sulfobetaine or the like. By containing in the molecule a hydrophilic group selected from zwitterionic hydrophilic groups, nonionic hydrophilic groups such as polyalkylene oxides, and / or 0.01 to 30% by weight of various surfactants in combination with the polyester resin. It is used after being made water-soluble and water-dispersed.
Specifically, JP-A-56-88454 and JP-A-57
-40525, JP-A-57-70177,
The method described in JP-A-57-212250 can be applied.

In order to obtain good corrosion resistance in the processed part and a stable aqueous solution or dispersion, it is most preferable to use a metal sulfonate base and / or a polyalkylene oxide alone or in combination as the hydrophilic group. The preferred amount of metal sulfonate base in the polyester resin is in the range of 0.1 to 8 wt% as sulfur. When it is less than 0.1% by weight, hydrophilicity is insufficient and good water solubility or water dispersibility cannot be obtained, and it is preferable to use polyalkylene glycol in combination. When it exceeds 8% by weight, the hydrophilicity of the chromate film becomes too strong, which is not preferable. The preferred amount of polyalkylene oxide in the polyester resin is 10-8.
0% by weight. If it is less than 10% by weight, the hydrophilicity is insufficient, and it is necessary to use a metal sulfonate base together.
If it exceeds 80% by weight, it is not preferable in terms of chromium elution and fingerprint resistance. Examples of the polyalkylene glycol include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and the like.
Polyethylene glycol is the most desirable in terms of corrosion resistance and water dispersibility of the processed part. The preferred molecular weight of the polyalkylene glycol is 500 to 20,000, more preferably 1000 to 10,000. When the molecular weight is less than 500, hydrophilicity is not sufficiently imparted, and when the molecular weight exceeds 20,000, compatibility with other components of the polyester resin is deteriorated and the resin becomes brittle, which is not preferable. The polyalkylene oxide and the repeating unit of other glycol may be random copolymers or block copolymers.

As a method of introducing the metal sulfonate base into the polyester, there are a method of reacting a compound having a metal sulfonate base with a polyester resin, a method of sulfonating the polyester resin to form a salt, etc. It is desirable to use compounds having a metal sulfonate base. Examples of the ester-forming dibasic acid component or glycol component having a metal sulfonate group include 5-sodium sulfoisophthalic acid, 5-potassium sulfoisophthalic acid, sodium sulfoterephthalic acid, 2-sodiumsulfo-1,4-butanediol,
Examples thereof include those containing a sulfonate such as 2,5-dimethyl-3-sodium sulfo-2,5-hexanediol. The sulfonate group is preferably an alkali metal salt, but may be a salt of quaternary nitrogen or phosphorus.

The glycol component of the polyester resin used in the present invention includes ethylene glycol, diethylene glycol, propylene glycol, 1,3-, in addition to polyalkylene oxide as a hydrophilic group for imparting water solubility or water dispersibility. Propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 2-ethyl-2-butyl-1,3-propanediol, 1,5-pentanediol, 3-methyl -1,5
-Pentanediol, 1,6-hexanediol, neopentyl glycol, triethylene glycol, dipropylene glycol, 2,2,4-trimethyl-1,3-
Pentanediol, polytetramethylene glycol, cyclohexane dimethanol, dimethylol tricyclodecane, bisphenol A or bisphenol F ethylene oxide adduct and propylene oxide adduct, hydrogenated bisphenol A or F ethylene oxide Examples thereof include adducts and propylene oxide adducts. Of these, ethylene glycol, neopentyl glycol, 1,3-propylene glycol, 2-methyl-1,3-propanediol, diethylene glycol, 1,5-pentanediol, 3-methyl-1,5-
Pentanediol, 1,6-hexanediol, cyclohexanedimethanol, and an ethylene oxide or propylene oxide adduct of bisphenol A are particularly preferable from the viewpoint of corrosion resistance of the processed part.

Further, polyhydric polyols such as trimethylolethane, trimethylolpropane, glycerin and pentaerythritol may be used in combination within a range not impairing the content of the invention. Further, in the polyester resin used in the present invention, after polymerizing the polyester resin, trimellitic anhydride, phthalic anhydride, pyromellitic anhydride, succinic anhydride, 1,8-naphthalic anhydride, 1,2-cyclohexane anhydride An acid value may be imparted by post-adding dicarboxylic acid or the like.

The number average molecular weight of the polyester resin used in the present invention is preferably in the range of 500 to 50,000, more preferably 1000 to 20,000. When the number average molecular weight is less than 500, the cohesive force of the resin is weak, the physical properties of the resin are poor, the corrosion resistance of the processed part is poor, and the chromium elution resistance is also poor. When the number average molecular weight exceeds 50,000, it is difficult to impart hydrophilicity, and good water solubility or water dispersibility cannot be obtained.

Examples of the water-soluble chromium compound (b) used in the present invention include chromic anhydride and reduced chromic acid obtained by partially reducing it, potassium (di) chromate, sodium (di) chromate, and (di) chromic acid. Examples thereof include dichromates such as ammonium and chromates, and among these, chromic anhydride or partially reduced chromic acid is preferable. The compounding ratio of the water-soluble chromium compound (b) and the aqueous solution and / or water dispersion of the polyester resin (a) in the resin chromate composition can be appropriately selected, but usually Cr of the water-soluble chromium compound is used.
The weight ratio of the weight in terms of O ₃ and the solid content of the polyester resin is preferably 1: 1 to 1:10.

The (c) mineral acid used in the resin chromate composition of the present invention includes phosphoric acid, sulfuric acid, hydrochloric acid, nitric acid, boric acid, etc. Phosphoric acid is preferred from the viewpoint of corrosion resistance and bath stability. The phosphoric acid used may be phosphoric acid, polyphosphoric acid, hypophosphorous acid, phosphorous acid, or the like. The addition amount can be selected as appropriate, but H ₃
The chromic acid concentration in the bath in terms of PO ₄ (in terms of CrO ₃ ) is 1.
It is desirable to add 0 times or more. In addition to these, Si
O ₂ , Cr ₂ O ₃ , Fe ₂ O ₃ , Fe ₃ O ₄ , MgO,
A sol such as ZrO ₂ , SnO ₂ , Al ₂ O ₃ , and Sb ₂ O ₅ , a fluoride, and the like can be present in the resin chromate composition and the coating, if necessary. The amount of the resin chromate film deposited is preferably in the range of 5 to 300 mg / m ^{2 in} terms of metal chromium. If it is 5 mg / m ² or less, the corrosion resistance is insufficient, and if it exceeds 300 mg / m ² , the weldability tends to decrease. Further, if necessary, it is preferable to add (d) colloidal silica from the viewpoint of corrosion resistance. As the colloidal silica, a particulate or chain aqueous dispersion is preferable.

As a method for treating a metal plate, coating with a roll coater, coating with a ringer roll, dipping and coating with an air knife, coating with a bar coater,
Application by spraying, application by curtain flow, etc. are mentioned. Next, the metal plate to which the present invention is applicable is a cold rolled steel plate, Zn, Zn-Ni system, Zn-Ni-Co system, Zn.
-Ni-Cr system, Zn-Fe system, Zn-Co system, Zn-
Zinc-based electric plating such as Cr-based, Zn-Mn, Zn-Al-based, Zn-Mg-based, hot dip plating, vapor deposition plated steel sheet, aluminum or aluminum alloy plated steel sheet, lead or lead alloy plated steel sheet, tin or tin alloy plating Steel plates and further these plating baths contain a small amount of dissimilar metal elements or impurities such as cobalt, tungsten, nickel, titanium, chromium, cadmium, manganese, iron, magnesium, lead, antimony, tin, copper and arsenic. And / or those in which an inorganic substance such as silica, alumina, and titania is dispersed. Further, the present invention can be applied to multilayer plating in which two or more kinds of the above plating are sequentially applied, or composite plating in which the above plating and other kinds of plating are combined. In addition, Ni, Cu, P
It can also be used for a plated steel sheet made of a metal such as b, Sn, Cd, Al or Ti, or an alloy of these metals. Among them, the resin chromate composition of the present invention is particularly excellent in the corrosion resistance of the processed part against the base material which causes cracks in the plating during the processing of hot-dip galvanized steel sheets and the like.

[0020]

The present invention will be specifically illustrated by the following examples. In the examples, “parts” means “parts by weight”. Evaluations in Examples and Comparative Examples were performed by the following methods.

1. Number average molecular weight The number average molecular weight in terms of polystyrene was measured using gel filtration chromatography (GPC).

2. Glass transition temperature Measured at a heating rate of 20 ° C./min using a differential scanning calorimeter (DSC). As a sample, 5 mg of the sample was placed in an aluminum pressing lid type container and crimped before use.

3. Preparation of test piece A predetermined resin chromate aqueous solution or a coating type chromate treatment aqueous solution is adhered on a predetermined metal-plated metal plate that has been degreased with alkali in advance, and the adhesion amount is 40 to 6 in terms of chromium after drying.
A test piece was obtained by coating with a roll so as to be 0 mg / m ² and drying under predetermined conditions.

4. Corrosion resistance of processed part 4. The test piece prepared in the above was subjected to 7 mm Erichsen extrusion from the back surface, and then a corrosion resistance test was performed. The evaluation was based on the occurrence of white rust at the Erichsen extruded portion. The corrosion test is a salt spray test based on JIS-Z-2371 standard (salt water concentration 5%, tank temperature 35 ° C, spray pressure 20PS).
I). The rusting condition after 120 hours and 360 hours was represented by 5 stages of ⊚, ○, Δ, ×, and XX. ◎: White rust occurrence rate 0% to 1% ○: White rust occurrence rate over 1% to 10% △: White rust occurrence rate over 10% to 30% ×: White rust occurrence rate over 30% to 50% XX: White rust occurrence rate over 50%

[5] Fingerprint resistance 4. Vaseline was applied to the chromate layer of the test piece prepared in the above, and the color difference (ΔE) before and after application was evaluated. The smaller the color difference, the better the fingerprint resistance. ⊚: ΔE <0.5 ○: 0.5 ≦ ΔE <1.0 Δ: 1.0 ≦ ΔE <2.0 ×: 2.0 ≦ ΔE <3.0 ××: 3.0 ≦ ΔE

6. Chromium elution resistance 4. Immerse the test piece in boiling water for 60 minutes,
The change rate of the chromium adhesion amount before and after that was measured. In addition,
The amount of chromium adhering was evaluated by atomic absorption analysis of chromium metal eluted in the solution, and evaluated by weight% with respect to chromium metal in the surface treatment film before immersion. ◎: Chromium reduction rate <2.0% ○: 2.0% ≤ Chromium reduction rate <5.0% △: 5.0% ≤ Chromium reduction rate <10.0% ×: 10.0% ≤ Chromium reduction rate <20.0% XX: 20.0% ≤ chromium reduction rate

Synthesis Example of Polyester Resin (A) 99.6 parts of terephthalic acid, 101 parts of 5-sodium sulfoisophthalic acid, 111 parts of ethylene glycol, and 0.102 of tetrabutyl titanate were placed in a reaction vessel equipped with a stirrer, a condenser and a thermometer. And 1.4 parts of sodium acetate were charged, and the esterification reaction was performed from 160 ° C. to 240 ° C. for 4 hours. Then, 42.8 parts of polyethylene glycol (molecular weight 1000) was charged, and the mixture was stirred at 210 ° C. for about 15 minutes. Then, the pressure inside the system was gradually reduced to 50 mmHg over 50 minutes, and further reduced to 0.
A polycondensation reaction was performed at 260 ° C. for 15 minutes under a vacuum of 3 mmHg or less. As a result of composition analysis such as NMR, the obtained polyester resin was found to have a molar ratio of acid component of terephthalic acid / 5-sodium sulfoisophthalic acid = 60/40 and glycol component of ethylene glycol / polyethylene glycol = 9.
It was 5/5. The sulfur content of 5-sodium sulfoisophthalic acid in the polyester resin was 4.6% by weight, and the content of polyethylene glycol was 18% by weight. The reduced viscosity of this polyester resin is 0.13d
It was 1 / g, the number average molecular weight was 2,200, and the glass transition temperature was about 9 ° C. Obtained polyester resin (A) 50
Parts and 450 parts of ion-exchanged water were charged into a flask equipped with a stirrer, a condenser and a thermometer, and dissolved by stirring at 80 ° C. for 3 hours. Then, it was cooled to room temperature to obtain an aqueous dispersion of polyester (A). This aqueous dispersion had a good stability and was a milky white liquid having a solution viscosity of 50 cps. The results are shown in Table 1.

Polyester Resin Synthesis Examples (B) to (I) Polyester Resins (B) to (I) as in Synthesis Example (A)
Was synthesized. The results are shown in Tables 1 and 2.

Comparative Synthesis Example (J) of Polyester Resin
(K) Comparative polyester resin (J) -as in Synthesis Example (A)
(K) was synthesized. The results are shown in Table 3.

Comparative Synthesis Example (L) of Acrylic Emulsion 400 parts of deionized water was put in a reaction tank to raise the liquid temperature to 60 ° C., 80 parts of methyl methacrylate and 8 parts of styrene.
0 part, butyl acrylate 188 parts, methacrylic acid 2
A solution of 0 part, 32 parts of 2-hydroxyethyl acrylate and 4 parts of ammonium persulfate in 96 parts of deionized water and a solution of 11 parts of acidic sodium sulfite in 89 parts of deionized water were simultaneously and in parallel for 2 hours. After completion of the dropwise addition with stirring, the polymerization reaction was continued with stirring at 60 ° C. for 3 hours. Thereafter, (O) to (P) were synthesized by the same method. The results are shown in Table 4.

Example 1 100 parts by weight of an aqueous dispersion of polyester resin (A) in an electrogalvanized steel sheet (basis weight: 30 mg / m ² ), 50% reduced chromic acid in terms of total chromic acid of 15 parts, phosphoric acid of 60 A resin chromate treatment liquid containing 1 part was applied and dried at 150 ° C. The corrosion resistance of the processed portion of the surface-treated steel sheet was very good even after 360 hours of the salt spray test, and surprisingly, the corrosion resistance was far better than that of the inorganic coating chromate of the comparative material. The chromium elution resistance and fingerprint resistance were also good. Table 5 shows the results.

Examples 2 to 9 Polyester resins (B) to (I) were blended in the same manner as in Example 1 and the bare corrosion resistance after processing, chromium elution resistance and fingerprint resistance were evaluated. The results are shown in Tables 5-6.

Comparative Examples 10 to 11 Polyester resins (J) to (M) were blended in the same manner as in Example 1 and the bare corrosion resistance after processing, chromium elution resistance and fingerprint resistance were evaluated. Table 7 shows the results.

Comparative Examples 12 to 16 Compounds were prepared by using an acrylic resin in the same manner as in Example 1, and the bare corrosion resistance after processing, chromium elution resistance and fingerprint resistance were evaluated. Table 8 shows the results.

Comparative Examples 17 to 18 Coating type chromate was prepared as a comparative example, and the bare corrosion resistance after processing, chromium elution resistance and fingerprint resistance were evaluated. Table 9 shows the results.

[0036]

[Table 1]

[0037]

[Table 2]

[0038]

[Table 3]

[0039]

[Table 4]

[0040]

[Table 5]

[0041]

[Table 6]

[0042]

[Table 7]

[0043]

[Table 8]

[0044]

[Table 9]

[0045]

EFFECT OF THE INVENTION By applying the resin chromate composition mainly composed of the polyester water-based resin of the present invention to various metal-plated metal plates or metal plates, the bare corrosion resistance of the processed part, which has been difficult to achieve technically in the past, has been difficult. And chromium elution resistance are both excellent and satisfying at a high level,
It is possible to obtain a resin chromate surface-treated metal plate having excellent appearance resistance and excellent fingerprint resistance.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshio Odajima 3-11-11 Kanaokahigashi-cho, Okayama-shi, Okayama (72) Inventor Chizo Takahashi 3-10-10 Kanaokahigashi-cho, Okayama-shi, Okayama

Claims (4)

[Claims] 1. An aqueous solution and / or an aqueous dispersion of a polyester resin, wherein (a) the aromatic dicarboxylic acid is 30 mol% or more of all the acid components, (b) a water-soluble chromium compound, and (c) one kind. A resin chromate composition comprising the above mineral acid. 2. An aqueous solution and / or an aqueous dispersion of a polyester resin, wherein (a) the aromatic dicarboxylic acid is 30 mol% or more of all the acid components, (b) a water-soluble chromium compound, and (c) one kind. A resin chromate composition comprising the above mineral acid and (d) colloidal silica. 3. The polyester resin contains 10 to 80% by weight of a polyalkylene oxide having a molecular weight of 500 to 20,000 as a copolymerization component, and 0.1 to 8% by weight of a metal sulfonate base as sulfur. The resin chromate composition according to claim 1 or 2, having a number average molecular weight of 1,000 to 50,000. 4. A film obtained from the resin chromate composition of claim 1 or 2 on a metal plate in terms of metal chromium.
A surface-treated metal plate having a content of ˜300 mg / m ² .