CA1112432A - Protective coating for metals - Google Patents
Protective coating for metalsInfo
- Publication number
- CA1112432A CA1112432A CA299,400A CA299400A CA1112432A CA 1112432 A CA1112432 A CA 1112432A CA 299400 A CA299400 A CA 299400A CA 1112432 A CA1112432 A CA 1112432A
- Authority
- CA
- Canada
- Prior art keywords
- composition
- acid
- tannin
- polymers
- organic
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
- B05D7/14—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials to metal, e.g. car bodies
- B05D7/16—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials to metal, e.g. car bodies using synthetic lacquers or varnishes
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
- C09D5/08—Anti-corrosive paints
- C09D5/082—Anti-corrosive paints characterised by the anti-corrosive pigment
- C09D5/086—Organic or non-macromolecular compounds
Landscapes
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Wood Science & Technology (AREA)
- Chemical & Material Sciences (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Paints Or Removers (AREA)
- Preventing Corrosion Or Incrustation Of Metals (AREA)
- Application Of Or Painting With Fluid Materials (AREA)
- Chemical Treatment Of Metals (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A chromium-free composition and process impart improved corrosion resistance and paint receptivity to a metal surface. The metal surface is contacted with an aqueous solution or dispersion of an organic film-forming polymer and an organic tannin.
A chromium-free composition and process impart improved corrosion resistance and paint receptivity to a metal surface. The metal surface is contacted with an aqueous solution or dispersion of an organic film-forming polymer and an organic tannin.
Description
~llZ43Z
P-10751.
I~C~CGROUNI) OF THE IN~!ENTI ON
_ The present invention relates to a process for forming a protective coating on the surface of metals to lmpr~ve the corrosion resistance and adhesion of top coated paints.
Zinc has been applied to the surface of steel by hot galvanizing or electroplating for the corrosion protection of steel However, zinc tends to develop white rust under humid con~itions which tends to degrade the appearance, to reduce the corrosion resistance of the base metal and to decrease the adhesion of top coated paints. The white rust on galvanized steel sheets has conventionally been prevented by ~ chromating p~ocess using a bath containing mainly chromic acid or its salts, While chromating affords inexpen-sive and excellent corrosion resistance, the presence of hexavalent chromium is objectionable from the standpoint of health and environment. Accordingly, it would be desirable to have a substitute for the chromating compositions which would impart satisfactory corrosion resistance and paint receptivity to the metal surface.
Japanese Patent Publication No, 2902/1976 discloses a process for treating the surface of metals, in particular steel, with tannic acid to inhibit the corrosion or to improve the adhesion of paint. The corrosion protection imparted by tannins is also generall~ disclosed in the literature such as Journal of Surface Treatment Association, Vol. 37, No. ~, ~2 (1964~, Journal of the Oil Color Chemistry Association, Vol. 41, 10 (1956). However, satisfactory corrosion protection o~ a zinc surface cannot be accomplished by such con~entional processes. In addition, when hot galvanized steel sheets are treated with tannic acid, the metallic luster is degraded.
~1~2432 At a p~ value from 6.5 to 9.0 which affords les~
change in the appearance, the tannin affords less reactivity with the surface, resulting in poor corrosion protection, and at a pH value of higher than 7.0, the tannin tends to decompose.
Further, while the corrosion resistance is improved with increas~
ed concentrations of tannin, the coating becomes powdery and thus reduces the adhesion of top coated paints.
On the other hand, when an aqueous solution or sus-pension of a water-~oluble or water-dispersible resin is applied to the surface of metals, the adhesion is extremely poor.
When a metal surface is treated with an aqueous solu-tion or suspension containing mainly a water-soluble or water-dispersible polymer, a process for treating the metal surface with the solution or disper~ion together with chromic acid or its salts has been ~uggested but the drawbacks of hexavalent chromium remain.
SUMMARY OF THE INVENTION
It has now been found that a passive coating can be formed with a better corrosion resistance and paint receptivity 20 than the known chromium-free coati~gs by contacting the metal surface with an aqueous neutral-to-acidic solution or sus-pension containing an organic tannin in an amount ranging from 0.1 to 20% by weight.
More specifically, the invention relates to an aqueous chromium-free composition useful for treating a metal surface comprising up to 40 wt.% of an org~nic film-forming polymer and from 0.1 to 20 wt.% of an organic tannin, the pH
value of the composition not exceeding 7.
The invention also relates to a process for forming an adhesive corrosion resistant coating on a metal surface com-prising contacting the surface with the above composition and thereafter drying the surface.
-` 1112432 DETAILED DESCRIPTION OF THE INVENTION
Metals to be treated according to this invention include iron, zinc or aluminum or alloys in which they pre-dominate including steel and galvanized steel.
The organic tannin usable in this invention may be any hydrolyzable tannin or condensed tannin or those containing their decomposition products and may include, - 2a -P-107sl l~lZ43Z
for exainI)le, depside tannin or gallotannin, Chinese tannin, hamamclitannin, tannic acid derived from Acer Ginnala, chebulinic acid, sumac tannin, Chinese gallotannin, ellagitannin, catechin, catechin-tannin, quebracho tannin and the like.
S The concentration of the tannin depends on the coating procedures ~ut ranges generally from 0.1 to 20% by weight.
In an amount of less than 0.1% by weight, little corrosion protection is imparted. At an amount of higher than 20%
by weight, the treating baths tend toward instability.
Conventional acid stable, water-soluble or water-dispersible polymers may be used in this invention and such polymers include, for example, vinylic polymers and copoly-mers derived from vinyl acetate, vinyl chloride, vinylidene chloride and the like; acrylic polymers and copolymers derived from acrylic acid, methacrylic acid, acrylates, methacrylates, hydroxyacrylic acid, hydroxymethacrylic acid and the like;
polymers and copolymers of alkyd type, epoxy type, fluorine type, polyester type, styrene type and olefine type; synthetic rubbers and naturally occurred pol~mers~ Aqueous solutions and dispersions containing one or~more such polymers or copoly-mers having molecular weight preferably higher than 1,000 and most preferabiy higher than 5,000 may be used in the process according to the invention.
The pH suitable for aqueous solutions or suspensions containing water-soluble or water-dispersible organic polymers and tannins ~ccording to the invention depends on the type of tannin, the type of metal to be treated and the coating process and conditions. The pH value will not normally exceed ? and usually ranges from 2 to 6,5, ~ a pH of les~
than 2, the reaction will occur too violently and may damage the surface appearance. At a pH of higher than 6.5, the reactivity with zinc is too weak to form a coating having good corrosion resistance. At a pH of higher than 7.0, the treating bath will usually be unstable due to decomposition of the tannin.
The adjustment of pH in the treating ~aths may be carried out, if necessary, by using any conventional pll adjusting compound; e.g., an inorganic acid such as phosphoric, nitric, sulfuric, hydrofluoric, hydrochloric, boric acids or a salt thereof; an organic acid such as oxalic, citric, malic, maleic, phthalic, lactic, tartaric, chloroacetic, acrylic, methacrylic acids or a salt thereof; alkali metal or ammonium hydroxides, carbonates, silicates and amines such as ethylamine, diethylamine, triethylamine, ethanolamine. In order to enhance the effects of the treating baths according to this invention, the baths may also include thiourea and/or a water-soluble titanium, zirconium, or hafnium compound~
When a zinc galvanized surface is treated and deformed, e.g., by bending or pressing, degreased and then painted directly, the coating remains so that it can serve as a paint base without applying further passivating treatments.
The present invention will be now illustrated by way of the following examples and comparative examples, but such examples should be construed by no means to limit the ~5 invention.
Hot galvanized steel sheets having a s~ze of lOOmm x lOOmm x 0.3mm treated temporarily with an anti-rust oil were spra~ed with an a~ueous solution of sodium tertiary phosphate in a concentration o~ 20 g/liter at 60C for 20 seconds and 1~12~3;~
rinsed with ~at~r. The cleaned galvanized steel sheets were then immersed in a treating bath prepared by mixing 500 ml of an aqueous demineralized water solution containing 50 g/l Chinese gallotannin (available from Fuji Chemicals Co. under ~ ) ~Rr~
5 ~3 the trade nR~ of Tann_c Acid AL) and 10 g/l thiourea with an aqueous suspension of an organic polymer prepared by diluting an emulsion containlng 100 g/l polyacrylate ester (available from Toyo Ink Co. under the trade ~e of Tocryl N-1~2) to 2,500 ml ~ith demineralized water and adjusting to a pH value of 3.5. The panels are immersed in this bath for a period of 1 minute at room temperature. The sheets were passed through rolls to remove excess liquid and then were dried in a hot circulating oven at 120C for 1 minute to form a coating.
Table 1 shows the results obtained by salt spray testing according to JIS~Z-2371.
COMPARATIVE EXAMPLE la Cleaned galvanized steel sheets pretreated in the same manner as in EXAMPLE 1 were immersed in an aqueous solution prepared by dissolving Chinese gallotannin (50 g) in demineralized water and making up to 1 liter and by adjusting the pH to 3.5 at room temperature for one minute, passed through rolls to squeeze excess liquid and dried in a hot air circulating oven at 120C for one minute. Table 1 also shows ~5 results obtained by testing these controls.
COMPARATIVE EXAMPLE lb Test pieces as used in Comparative Example la, were coated with an emulsion of polyacrylate as used in Example 1 in a consis~ency of 100 g/liter in an amount of about 10 g~m2 by bar coating procedure and dried in a hot air recycling ovell at 120~C for one minute to~form a coating.
Table 1 shows again results obtained by testing such coatings.
Table 1 24 Hour Salt spraY
Test Results Appearance of Coating -% White Rust Example 1 Clear and colorless 0 Comparative Example la Milky White 80-90%
Comparative Example lb Clear and colorless 100%
Test panels prepared as in Example 1 and Comparative Examples la and lb, respectively, were coated with an alkyd me-lamine paint (available from Dainippon Toryo Co. under the trade mark of Delicon No. 700 White) by bar coating procedure and baked in a hot air circulating oven at 140C for 25 minutes to provide a paint film having a thickness of about 30 microns.
Table 2 shows results of the cross hatch test, Erichsen test, impact test and salt spray corrosion test for the painted panels of the example and comparative examples.
Corrosion testing of the painted panels was carried out by scribing the paint film to the base metal by means of a knife edge and subjecting the sheets to the salt spray test ac-cording to JIS-Z-2371 for 120 hours. The coated surfaces were then rinsed with water, dried and the corroded width (creepage) was measured by applying Cellophane tape to the scribe and peeling rapidly. Cellophane is a trade mark. Table 2 shows the results obtained.
Table 2 Adhesion of Painted Film ~ec~n 120 Hr.
Cross hatch` Erich ~ Impact Salt Spray Creepage - mm test test test _ _ .
S EX ~ le 2 100/100100/lQ0 No ~val 3 ~arative EXample 2a 100/100 50/100 ~50~ n~val 10 C~rative Example 2b 100/100 100/100 ~o ~val 10 Cross-Hatching test~
The film was cxoss-hatched to form 100 squares having a size of 1 x 1 mm by scribing to the base metal and applying T~ Ce ~/~ c ~ and peelin~ ecllop~4 tape from the cross-hatched squares.
The result ~a~ represented by the number of unstripped squares/100 squares.
Erichsen test:
The film was cross-hatched to form 100 squares having a si2e of 1 mm x 1 mm. The sheet was then pressed by means of/an ~icl~en tester to a convex displacement of 5 mm e ,~ ~e and o~ll~rh~c-tape ~as applied to the deformed squares and then removed~ Xesults are reported as in the Cross-hatch test.
Impact test: ~
The film wa~ impacted by a weight having a diameter of 1~2 inches, a io~d of 500 g, and falling a distance of 50 cm on a D~Pont impact tester. Cellophane tape was applied to the convex de~orination and yeeled off.
Test panels ~ere prepared as in Example 1 and Compaxative Examples la and lb kut, after coating, were cleaned with an ~eous alkaline cleaner ~available from P-10751 lllZ43~
B Nihon Parkeri7.ing Co.l I.td. under the trade 3aM~ of l~ine-cleaner 4326) having a concentration of 20 g/liter, by spraying for 60 seconds at a temperature of 60C. The clean panels were then subjected to salt spray test according to JIS-Z-2371 to test the corrosion resistance of the protective coating prepared by Example 1 and Comparative Examples la and lb.
Table 3 24 Hour 120 Hour S~t Spray < Spray Specimen Creepage - mm -% White Rust Example 1 10-20% 5 ~arative ~le la 100% 10 Camparative Example lb 100% 10 ~ -Untreated sheet 100% 10
P-10751.
I~C~CGROUNI) OF THE IN~!ENTI ON
_ The present invention relates to a process for forming a protective coating on the surface of metals to lmpr~ve the corrosion resistance and adhesion of top coated paints.
Zinc has been applied to the surface of steel by hot galvanizing or electroplating for the corrosion protection of steel However, zinc tends to develop white rust under humid con~itions which tends to degrade the appearance, to reduce the corrosion resistance of the base metal and to decrease the adhesion of top coated paints. The white rust on galvanized steel sheets has conventionally been prevented by ~ chromating p~ocess using a bath containing mainly chromic acid or its salts, While chromating affords inexpen-sive and excellent corrosion resistance, the presence of hexavalent chromium is objectionable from the standpoint of health and environment. Accordingly, it would be desirable to have a substitute for the chromating compositions which would impart satisfactory corrosion resistance and paint receptivity to the metal surface.
Japanese Patent Publication No, 2902/1976 discloses a process for treating the surface of metals, in particular steel, with tannic acid to inhibit the corrosion or to improve the adhesion of paint. The corrosion protection imparted by tannins is also generall~ disclosed in the literature such as Journal of Surface Treatment Association, Vol. 37, No. ~, ~2 (1964~, Journal of the Oil Color Chemistry Association, Vol. 41, 10 (1956). However, satisfactory corrosion protection o~ a zinc surface cannot be accomplished by such con~entional processes. In addition, when hot galvanized steel sheets are treated with tannic acid, the metallic luster is degraded.
~1~2432 At a p~ value from 6.5 to 9.0 which affords les~
change in the appearance, the tannin affords less reactivity with the surface, resulting in poor corrosion protection, and at a pH value of higher than 7.0, the tannin tends to decompose.
Further, while the corrosion resistance is improved with increas~
ed concentrations of tannin, the coating becomes powdery and thus reduces the adhesion of top coated paints.
On the other hand, when an aqueous solution or sus-pension of a water-~oluble or water-dispersible resin is applied to the surface of metals, the adhesion is extremely poor.
When a metal surface is treated with an aqueous solu-tion or suspension containing mainly a water-soluble or water-dispersible polymer, a process for treating the metal surface with the solution or disper~ion together with chromic acid or its salts has been ~uggested but the drawbacks of hexavalent chromium remain.
SUMMARY OF THE INVENTION
It has now been found that a passive coating can be formed with a better corrosion resistance and paint receptivity 20 than the known chromium-free coati~gs by contacting the metal surface with an aqueous neutral-to-acidic solution or sus-pension containing an organic tannin in an amount ranging from 0.1 to 20% by weight.
More specifically, the invention relates to an aqueous chromium-free composition useful for treating a metal surface comprising up to 40 wt.% of an org~nic film-forming polymer and from 0.1 to 20 wt.% of an organic tannin, the pH
value of the composition not exceeding 7.
The invention also relates to a process for forming an adhesive corrosion resistant coating on a metal surface com-prising contacting the surface with the above composition and thereafter drying the surface.
-` 1112432 DETAILED DESCRIPTION OF THE INVENTION
Metals to be treated according to this invention include iron, zinc or aluminum or alloys in which they pre-dominate including steel and galvanized steel.
The organic tannin usable in this invention may be any hydrolyzable tannin or condensed tannin or those containing their decomposition products and may include, - 2a -P-107sl l~lZ43Z
for exainI)le, depside tannin or gallotannin, Chinese tannin, hamamclitannin, tannic acid derived from Acer Ginnala, chebulinic acid, sumac tannin, Chinese gallotannin, ellagitannin, catechin, catechin-tannin, quebracho tannin and the like.
S The concentration of the tannin depends on the coating procedures ~ut ranges generally from 0.1 to 20% by weight.
In an amount of less than 0.1% by weight, little corrosion protection is imparted. At an amount of higher than 20%
by weight, the treating baths tend toward instability.
Conventional acid stable, water-soluble or water-dispersible polymers may be used in this invention and such polymers include, for example, vinylic polymers and copoly-mers derived from vinyl acetate, vinyl chloride, vinylidene chloride and the like; acrylic polymers and copolymers derived from acrylic acid, methacrylic acid, acrylates, methacrylates, hydroxyacrylic acid, hydroxymethacrylic acid and the like;
polymers and copolymers of alkyd type, epoxy type, fluorine type, polyester type, styrene type and olefine type; synthetic rubbers and naturally occurred pol~mers~ Aqueous solutions and dispersions containing one or~more such polymers or copoly-mers having molecular weight preferably higher than 1,000 and most preferabiy higher than 5,000 may be used in the process according to the invention.
The pH suitable for aqueous solutions or suspensions containing water-soluble or water-dispersible organic polymers and tannins ~ccording to the invention depends on the type of tannin, the type of metal to be treated and the coating process and conditions. The pH value will not normally exceed ? and usually ranges from 2 to 6,5, ~ a pH of les~
than 2, the reaction will occur too violently and may damage the surface appearance. At a pH of higher than 6.5, the reactivity with zinc is too weak to form a coating having good corrosion resistance. At a pH of higher than 7.0, the treating bath will usually be unstable due to decomposition of the tannin.
The adjustment of pH in the treating ~aths may be carried out, if necessary, by using any conventional pll adjusting compound; e.g., an inorganic acid such as phosphoric, nitric, sulfuric, hydrofluoric, hydrochloric, boric acids or a salt thereof; an organic acid such as oxalic, citric, malic, maleic, phthalic, lactic, tartaric, chloroacetic, acrylic, methacrylic acids or a salt thereof; alkali metal or ammonium hydroxides, carbonates, silicates and amines such as ethylamine, diethylamine, triethylamine, ethanolamine. In order to enhance the effects of the treating baths according to this invention, the baths may also include thiourea and/or a water-soluble titanium, zirconium, or hafnium compound~
When a zinc galvanized surface is treated and deformed, e.g., by bending or pressing, degreased and then painted directly, the coating remains so that it can serve as a paint base without applying further passivating treatments.
The present invention will be now illustrated by way of the following examples and comparative examples, but such examples should be construed by no means to limit the ~5 invention.
Hot galvanized steel sheets having a s~ze of lOOmm x lOOmm x 0.3mm treated temporarily with an anti-rust oil were spra~ed with an a~ueous solution of sodium tertiary phosphate in a concentration o~ 20 g/liter at 60C for 20 seconds and 1~12~3;~
rinsed with ~at~r. The cleaned galvanized steel sheets were then immersed in a treating bath prepared by mixing 500 ml of an aqueous demineralized water solution containing 50 g/l Chinese gallotannin (available from Fuji Chemicals Co. under ~ ) ~Rr~
5 ~3 the trade nR~ of Tann_c Acid AL) and 10 g/l thiourea with an aqueous suspension of an organic polymer prepared by diluting an emulsion containlng 100 g/l polyacrylate ester (available from Toyo Ink Co. under the trade ~e of Tocryl N-1~2) to 2,500 ml ~ith demineralized water and adjusting to a pH value of 3.5. The panels are immersed in this bath for a period of 1 minute at room temperature. The sheets were passed through rolls to remove excess liquid and then were dried in a hot circulating oven at 120C for 1 minute to form a coating.
Table 1 shows the results obtained by salt spray testing according to JIS~Z-2371.
COMPARATIVE EXAMPLE la Cleaned galvanized steel sheets pretreated in the same manner as in EXAMPLE 1 were immersed in an aqueous solution prepared by dissolving Chinese gallotannin (50 g) in demineralized water and making up to 1 liter and by adjusting the pH to 3.5 at room temperature for one minute, passed through rolls to squeeze excess liquid and dried in a hot air circulating oven at 120C for one minute. Table 1 also shows ~5 results obtained by testing these controls.
COMPARATIVE EXAMPLE lb Test pieces as used in Comparative Example la, were coated with an emulsion of polyacrylate as used in Example 1 in a consis~ency of 100 g/liter in an amount of about 10 g~m2 by bar coating procedure and dried in a hot air recycling ovell at 120~C for one minute to~form a coating.
Table 1 shows again results obtained by testing such coatings.
Table 1 24 Hour Salt spraY
Test Results Appearance of Coating -% White Rust Example 1 Clear and colorless 0 Comparative Example la Milky White 80-90%
Comparative Example lb Clear and colorless 100%
Test panels prepared as in Example 1 and Comparative Examples la and lb, respectively, were coated with an alkyd me-lamine paint (available from Dainippon Toryo Co. under the trade mark of Delicon No. 700 White) by bar coating procedure and baked in a hot air circulating oven at 140C for 25 minutes to provide a paint film having a thickness of about 30 microns.
Table 2 shows results of the cross hatch test, Erichsen test, impact test and salt spray corrosion test for the painted panels of the example and comparative examples.
Corrosion testing of the painted panels was carried out by scribing the paint film to the base metal by means of a knife edge and subjecting the sheets to the salt spray test ac-cording to JIS-Z-2371 for 120 hours. The coated surfaces were then rinsed with water, dried and the corroded width (creepage) was measured by applying Cellophane tape to the scribe and peeling rapidly. Cellophane is a trade mark. Table 2 shows the results obtained.
Table 2 Adhesion of Painted Film ~ec~n 120 Hr.
Cross hatch` Erich ~ Impact Salt Spray Creepage - mm test test test _ _ .
S EX ~ le 2 100/100100/lQ0 No ~val 3 ~arative EXample 2a 100/100 50/100 ~50~ n~val 10 C~rative Example 2b 100/100 100/100 ~o ~val 10 Cross-Hatching test~
The film was cxoss-hatched to form 100 squares having a size of 1 x 1 mm by scribing to the base metal and applying T~ Ce ~/~ c ~ and peelin~ ecllop~4 tape from the cross-hatched squares.
The result ~a~ represented by the number of unstripped squares/100 squares.
Erichsen test:
The film was cross-hatched to form 100 squares having a si2e of 1 mm x 1 mm. The sheet was then pressed by means of/an ~icl~en tester to a convex displacement of 5 mm e ,~ ~e and o~ll~rh~c-tape ~as applied to the deformed squares and then removed~ Xesults are reported as in the Cross-hatch test.
Impact test: ~
The film wa~ impacted by a weight having a diameter of 1~2 inches, a io~d of 500 g, and falling a distance of 50 cm on a D~Pont impact tester. Cellophane tape was applied to the convex de~orination and yeeled off.
Test panels ~ere prepared as in Example 1 and Compaxative Examples la and lb kut, after coating, were cleaned with an ~eous alkaline cleaner ~available from P-10751 lllZ43~
B Nihon Parkeri7.ing Co.l I.td. under the trade 3aM~ of l~ine-cleaner 4326) having a concentration of 20 g/liter, by spraying for 60 seconds at a temperature of 60C. The clean panels were then subjected to salt spray test according to JIS-Z-2371 to test the corrosion resistance of the protective coating prepared by Example 1 and Comparative Examples la and lb.
Table 3 24 Hour 120 Hour S~t Spray < Spray Specimen Creepage - mm -% White Rust Example 1 10-20% 5 ~arative ~le la 100% 10 Camparative Example lb 100% 10 ~ -Untreated sheet 100% 10
Claims (6)
1. An aqueous chromium-free composition useful for treating a metal surface comprising up to 40 wt.% of an organic film-forming polymer and from 0.1 to 20 wt.% of an organic tannin, the pH value of the composition not exceeding 7.
2. The composition of Claim 1 wherein the concentration of the tannin material is between 1 and 5 wt.% and the pH
value of the composition is from 2.0 to 6.5.
value of the composition is from 2.0 to 6.5.
3. The composition of Claim 1 wherein the polymer is selected from the group of film-forming polymers consisting of vinylic polymers and copolymers of vinyl acetate, vinyl chloride, and vinylidene chloride; polymers and copolymers of acrylic acid, methacrylic acid, acrylic acid esters, meth-acrylic acid esters, hydroxyacrylic acid, and hydroxymeth-acrylic acid; alkyd-, epoxy-, fluorine-containing, urethane, polyester, styrene and olefinic polymers and copolymers; syn-thetic rubber such as butadiene rubber; and naturally occurr-ing organic polymers.
4. The composition of Claim 1, 2 or 3 wherein the organic tannin is selected from the group consisting of depside tannin, gallotannin, Chinese tannic acid, Turkey tannic acid, hamamelitannic acid, tannic acid from Acer Ginnala, chebulinic acid, sumac, Chinese gallotannin, ellagitannin, catechin and quebracho.
5. The composition of Claim 1, 2 or 3 containing at least one adjuvant selected from the group consisting of pig-ments, plasticizers, high boiling organic solvents and surfac-tants.
6. A process for forming an adhesive corrosion resis-tant coating on a metal surface comprising contacting the surface with the composition of Claim 1, 2 or 3 and there-after drying the surface.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP30,488/77 | 1977-03-22 | ||
| JP3048877A JPS53116240A (en) | 1977-03-22 | 1977-03-22 | Method of forming top coat of metal |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1112432A true CA1112432A (en) | 1981-11-17 |
Family
ID=12305211
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA299,400A Expired CA1112432A (en) | 1977-03-22 | 1978-03-21 | Protective coating for metals |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JPS53116240A (en) |
| AU (1) | AU520635B2 (en) |
| CA (1) | CA1112432A (en) |
| GB (1) | GB1572210A (en) |
| ZA (1) | ZA781666B (en) |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS582590B2 (en) * | 1978-11-02 | 1983-01-17 | 新日本製鐵株式会社 | Chemical conversion treatment method for manganese-plated steel materials |
| GB2075538B (en) * | 1980-05-02 | 1983-12-21 | Applied Coating Tech Inc | Stable latex rust converting primer |
| JPS614775A (en) * | 1984-06-19 | 1986-01-10 | Shuji Kimura | Rust-inhibiting resin |
| DE69921787T2 (en) | 1998-02-18 | 2005-10-27 | Nippon Paint Co., Ltd. | CORROSION PROTECTION COATING AND PROCESSING FOR CORROSION PROTECTION |
| US20050183793A1 (en) * | 2004-02-25 | 2005-08-25 | Hyung-Joon Kim | Method of improving the performance of organic coatings for corrosion resistance |
| JP5571881B2 (en) | 2008-06-07 | 2014-08-13 | 日本パーカライジング株式会社 | Surface treatment liquid for autodeposition coating treatment of metal material, and autodeposition coating treatment method |
| WO2011055415A1 (en) | 2009-11-09 | 2011-05-12 | トヨタ自動車株式会社 | Exhaust device of internal combustion engine |
| CN106581778B (en) * | 2015-10-14 | 2020-07-21 | 先健科技(深圳)有限公司 | Absorbable iron-based alloy implanted medical instrument and preparation method thereof |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5247535A (en) * | 1975-10-15 | 1977-04-15 | Nippon Steel Corp | Process for forming rusttproofing underlayer on metallic articles |
-
1977
- 1977-03-22 JP JP3048877A patent/JPS53116240A/en active Granted
-
1978
- 1978-03-21 AU AU34354/78A patent/AU520635B2/en not_active Expired
- 1978-03-21 GB GB11063/78A patent/GB1572210A/en not_active Expired
- 1978-03-21 CA CA299,400A patent/CA1112432A/en not_active Expired
- 1978-03-22 ZA ZA00781666A patent/ZA781666B/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| ZA781666B (en) | 1979-02-28 |
| AU520635B2 (en) | 1982-02-18 |
| JPS5631876B2 (en) | 1981-07-24 |
| GB1572210A (en) | 1980-07-23 |
| AU3435478A (en) | 1979-09-27 |
| JPS53116240A (en) | 1978-10-11 |
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| MKEX | Expiry |