CA1050211A - Method of neutralizing surface color caused by anodizing aluminum alloys - Google Patents
Method of neutralizing surface color caused by anodizing aluminum alloysInfo
- Publication number
- CA1050211A CA1050211A CA220,999A CA220999A CA1050211A CA 1050211 A CA1050211 A CA 1050211A CA 220999 A CA220999 A CA 220999A CA 1050211 A CA1050211 A CA 1050211A
- Authority
- CA
- Canada
- Prior art keywords
- color
- dye
- sealing
- cast
- aluminum
- 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
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
- C25D11/02—Anodisation
- C25D11/04—Anodisation of aluminium or alloys based thereon
- C25D11/18—After-treatment, e.g. pore-sealing
- C25D11/24—Chemical after-treatment
- C25D11/246—Chemical after-treatment for sealing layers
-
- 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
- B05D5/00—Processes for applying liquids or other fluent materials to surfaces to obtain special surface effects, finishes or structures
- B05D5/06—Processes for applying liquids or other fluent materials to surfaces to obtain special surface effects, finishes or structures to obtain multicolour or other optical effects
- B05D5/067—Metallic effect
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
- C25D11/02—Anodisation
- C25D11/04—Anodisation of aluminium or alloys based thereon
- C25D11/18—After-treatment, e.g. pore-sealing
- C25D11/24—Chemical after-treatment
- C25D11/243—Chemical after-treatment using organic dyestuffs
-
- 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
- B05D2202/00—Metallic substrate
- B05D2202/20—Metallic substrate based on light metals
- B05D2202/25—Metallic substrate based on light metals based on Al
-
- 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
- B05D3/00—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
- B05D3/10—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by other chemical means
- B05D3/102—Pretreatment of metallic substrates
Landscapes
- Chemical & Material Sciences (AREA)
- General Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Chemical Treatment Of Metals (AREA)
- Electrochemical Coating By Surface Reaction (AREA)
Abstract
METHOD OF NEUTRALIZING SURFACE COLOR
CAUSED BY ANODIZING ALUMINUM ALLOYS
Abstract of the Disclosure A surface color modification caused by anodizing certain, aluminum alloys is neutralized by sealing the anodized surface in an aqueous solution containing a specific dye. The dye neutralizes said color modification without leaving a color of its own.
CAUSED BY ANODIZING ALUMINUM ALLOYS
Abstract of the Disclosure A surface color modification caused by anodizing certain, aluminum alloys is neutralized by sealing the anodized surface in an aqueous solution containing a specific dye. The dye neutralizes said color modification without leaving a color of its own.
Description
: ~
¦ Backqround of the Invention The present invention relates to the co_rection of a surface color modification caused by anodizing certain aluminum alloys and more particularly to a method of neutralizing said ¦ color modification with a dye-containing sealing solution.
¦ It is known that anodizing certain aluminum alloys can modify the surface color. In copper-containing aluminum alloys, for example~ this color appears as a yellow cast. In some applications, the appearance of this cast is not detrimental to ¦ th~ final product. When the product is to be used for decorative ¦ purposes, however, the cast may be considered undesirable, for example, in the case of aluminum automobile bumpers.
¦ A known method to eliminate or reduce this undesired ¦ cast is to lower the current density during anodizing to 2 level whereby the cast is diminished. This method has the I disadvantages of slowing production and producing an anodic ¦ coating of inferior corrosion resistance.
I -1- ~
-- - : , . : : :
- - ~
.
-.-, ~ ': ' :'.: ' : ~
- : . : - :. :
~050Zll of course, manufacturers have the option to plate the aluminum surface instead of anodizincJ it. If the aluminum is to be used for automobile bumpers, for example, it can be eléctro-plated with nickel and chromium. Electroplating, however, is expensive and the corrosion resistance of the resulting surface is unpredictable.
Contrary to the objectives of the present invention, some decorative uses of aluminum require a colored surface.
In these cases, a surface color modification caused by anodi-zing may be desired and can even be enhanced with dyes. More- !
over, dyes of any desired color, if used in sufficient quantity, may be used to impart color to the anodized surface. Dyeing is most commonly carried out prior to sealing. However, some methods of dyeing and sealing in a single step are known.
In U.S. Patent 2J683,113, a method of coloring aluminum ice trays is described wherein the anodized tray is placed in an aqueous solution of an organic dye. The dye is added to the solution in a sufficient quantity to yield the desired color. By maintaining the dye bath at a temperature of between about 175 and 210F. the surface is sealed simultaneously with dyeing.
Another method of dyeing and sealing anodized aluminum in a single step is described in U S Patent ~o 3~079~309. In this method, anodized aluminum is colored by applying an ink composition consisting essentially of a water soluble organic hydroxy compound having a boiling point greater than 212F., a ~ ' :
¦ Backqround of the Invention The present invention relates to the co_rection of a surface color modification caused by anodizing certain aluminum alloys and more particularly to a method of neutralizing said ¦ color modification with a dye-containing sealing solution.
¦ It is known that anodizing certain aluminum alloys can modify the surface color. In copper-containing aluminum alloys, for example~ this color appears as a yellow cast. In some applications, the appearance of this cast is not detrimental to ¦ th~ final product. When the product is to be used for decorative ¦ purposes, however, the cast may be considered undesirable, for example, in the case of aluminum automobile bumpers.
¦ A known method to eliminate or reduce this undesired ¦ cast is to lower the current density during anodizing to 2 level whereby the cast is diminished. This method has the I disadvantages of slowing production and producing an anodic ¦ coating of inferior corrosion resistance.
I -1- ~
-- - : , . : : :
- - ~
.
-.-, ~ ': ' :'.: ' : ~
- : . : - :. :
~050Zll of course, manufacturers have the option to plate the aluminum surface instead of anodizincJ it. If the aluminum is to be used for automobile bumpers, for example, it can be eléctro-plated with nickel and chromium. Electroplating, however, is expensive and the corrosion resistance of the resulting surface is unpredictable.
Contrary to the objectives of the present invention, some decorative uses of aluminum require a colored surface.
In these cases, a surface color modification caused by anodi-zing may be desired and can even be enhanced with dyes. More- !
over, dyes of any desired color, if used in sufficient quantity, may be used to impart color to the anodized surface. Dyeing is most commonly carried out prior to sealing. However, some methods of dyeing and sealing in a single step are known.
In U.S. Patent 2J683,113, a method of coloring aluminum ice trays is described wherein the anodized tray is placed in an aqueous solution of an organic dye. The dye is added to the solution in a sufficient quantity to yield the desired color. By maintaining the dye bath at a temperature of between about 175 and 210F. the surface is sealed simultaneously with dyeing.
Another method of dyeing and sealing anodized aluminum in a single step is described in U S Patent ~o 3~079~309. In this method, anodized aluminum is colored by applying an ink composition consisting essentially of a water soluble organic hydroxy compound having a boiling point greater than 212F., a ~ ' :
-2-~
. . -coloring material dissolved therein, a viscosity control agent compatible with and chemically inert toward the remaining constituents in the composition and a finely divided filling agent consisting of porous particles of solid, inorganic pigment which also is chemically inert toward the remaining constituents in the composition.
In accordance with a method described in U.S. Patent No. 3,767,474, surface color modifications caused by anodizing may be enhanced, or in the alternative, a different color may be imparted to the anodized surface by sealing the anodized sur-face with a hot aqueous solution containing disodium 4-dodecylated oxydibenzene sulfonate, a soluble hydrolyzable metallic salt and a dye compatible with the other constituents of said solution.
Summary of the Invention It has now been discovered that the undesired cast appearing in the anodized surface of certain aluminum alloys can be simply and economically neutralized by contacting said surface with an aqueous sealing solution containing a specific dye. Thus, in accordance with the present invention there is provided a new method for eliminating undesired surface color modifications imparted to aluminum as the result of anodizing.
Thus, in accordance with the present teachings, a method is provided of neutralizing an undesired cast appearing in an anodized surface of an aluminum alloy, by sealing the anodized surface for about 10 to 30 minutes with an aqueous solution containing a monoazo metallic dye of `~
a color and in a concentration of between 3 and 30 mg. per liter and sufficient to neutralize the undesired cast without -imparting the dye color. The solution is maintained at a pH between about 5.5 and 6O5 - 0.1 and a temperature between t~ ~
~ ~ - 3 -.
- :. -~0~1 -t about 180 and 210F - 5F.
Prior to anodizing, the aluminum workpiece can be chemically brightened if desired. The workpiece then is anodized at a current density sufficient to produce an anodic coating having good corrosion resistance. It is preferred to anodize at ~-
. . -coloring material dissolved therein, a viscosity control agent compatible with and chemically inert toward the remaining constituents in the composition and a finely divided filling agent consisting of porous particles of solid, inorganic pigment which also is chemically inert toward the remaining constituents in the composition.
In accordance with a method described in U.S. Patent No. 3,767,474, surface color modifications caused by anodizing may be enhanced, or in the alternative, a different color may be imparted to the anodized surface by sealing the anodized sur-face with a hot aqueous solution containing disodium 4-dodecylated oxydibenzene sulfonate, a soluble hydrolyzable metallic salt and a dye compatible with the other constituents of said solution.
Summary of the Invention It has now been discovered that the undesired cast appearing in the anodized surface of certain aluminum alloys can be simply and economically neutralized by contacting said surface with an aqueous sealing solution containing a specific dye. Thus, in accordance with the present invention there is provided a new method for eliminating undesired surface color modifications imparted to aluminum as the result of anodizing.
Thus, in accordance with the present teachings, a method is provided of neutralizing an undesired cast appearing in an anodized surface of an aluminum alloy, by sealing the anodized surface for about 10 to 30 minutes with an aqueous solution containing a monoazo metallic dye of `~
a color and in a concentration of between 3 and 30 mg. per liter and sufficient to neutralize the undesired cast without -imparting the dye color. The solution is maintained at a pH between about 5.5 and 6O5 - 0.1 and a temperature between t~ ~
~ ~ - 3 -.
- :. -~0~1 -t about 180 and 210F - 5F.
Prior to anodizing, the aluminum workpiece can be chemically brightened if desired. The workpiece then is anodized at a current density sufficient to produce an anodic coating having good corrosion resistance. It is preferred to anodize at ~-
- 3~ -~.
~l iO~iOZll I a current density between about 12 and 24 amperes per square foot j for about 15 to 30 minutes. If the anodizing step causes an ¦ undesired cast to be imparted to the anodized surface, a dye ic selected to neutralize that cast.
¦ It is critical to select the dye on the basis of ¦ its ability to neutralize the undesired cast without leaving ¦ a color of its own. Dyes having the color characteristics necessary to neutralize the undesired cast are selected on the ¦ basis of a color system such as the Munsell color system. When ¦ the Munsell system is used, the hue corresponding to the ¦ undesired cast is found on the 100 hue Munsell color circle.
¦ The color opposite the position~on that circle, of said cor- ~
¦ responding hue, i.e. 180 from that position~ is normally the I -¦ neutralizing color. A dye having said neutralizing color then ¦ is selected. Suitable dyes include the monoazo acid metallized l type, among others.
¦ Several dyes may appear to be satisfactory. However, ¦ each dye must be t:ested to determine which dyes of those selected will not leave a color of their own in the anodized surface. ¦ I
Testing may be carried out on a laboratory scale by contacting I samples of anodized aluminum having the undesired cast with aqueou.s I
l sealing solutions containing the individual dyes. (The compos- ¦
¦ ition of said solutions is defined below.) The sealed samples ¦ are visually inspected and the specific dye or dyes that yield ¦ best results are thereby selected.
The specific dye is added in a concentration of between about 3 and 30 milligrams per liter to water, thus making-up the _4_ .
` .
I aqueous sealing solution. Sealing accelerators such as metallic ¦ salts, for example, Co or Ni salts~ can be added to the solution.
¦ The use of accelerators, however, makes color control difficult.
¦ It is critical that the concentration of the dye is below ~he ¦ value that would cause coloring of the anodized surface and is ¦ at or above the value necessary to effect neutralization of the ¦ undesired cast. Minor variations will easily establish the ¦ optimum concentration range for the specific dye. In a ¦ continuous process, the optimum concentration range is maintained .0 ¦ with the aid of a colorimeter or spectrophotometer.
l Also critical to the method of the present invention ¦ is the maintenance of the pH of the solution within a range ¦ that is optimum for sealing and dye absorption. The pH must be ¦ between about 5.5 and 6.5. Selectlon of a pH value is based on ¦ the desired rate of sealing. Sealing rate decreases with ¦ increased acidity. Once a pH value is selected~ it must be I controlled to + 0.1. Sodium hydroxide or acetic acid is used to ¦ control the pH.
¦ The temperature of the solution must be maintained at a ~0 1 value sufficient to effect sealing of the anodized surface. A
l temperature between about 180 and 210F. is selected and I ¦ maintained at + 5F.
¦ Sealing according to the present invention is effected by contacting the anodized aluminum with the dye-containing ~5 1 sealing solution for about lO to 30 minutes.
¦ ~he present invention will be more fully illustrated ¦ in the example which follows:
.
,' ~ .
. - 5 -. ~
EXAMPLE
A high strength aluminum alloy utilized in the manu-facture of bumpers for automobiles was chemically brightened by a conventional process. The alloy had the following composition:
1.0% magnesium, o.8% copper, 4.5~ zinc, less than 0.1~ iron, less than 0.1~ silicon, 0.05~ titanium and the balance; high purity aluminum ingot. Anodizing was effected at a standard current density of 14 amperes per square foot until the anodic coating was between about 0.00~4 and 0.0005 inch thick. The anodized product had an undesired yellow cast. On the basis of the Munsell Color System, five dyes of neutralizing color were selected, namely, aluminum black-c-conc, aluminum grey NL paste, aluminum black 2 LW, aluminum fast black GL paste, and aluminum black V. All dyes were from Sandoz Colors and Chemicals.
A sealing solution having a dye concentration of about 15 milligrams per liter was maintained at a pH between 5.6 and 5.7, with sodium hydroxide and acetic acid. A sealing solution temperature of about 205F. ~ 5F. wa~ used. The anodized alloy was immersed in the solution for 15 minutes. As the result of experimentation w.ith the above-dyes under these conditions, it was found that aluminum black V (also known as acid black 52, a monoazo metallic dye having the chemical formula:
N307SC2oHl 3 xCr Na and a color index of 15,711) successfully neutralized the undesired yellow cast without leaving a color of its own.
Having set forth the general nature and an exemplary embodiment of the present invention, the scope is now par~icu rly pointed out in the appended claims.
~ - 6 -.
~l iO~iOZll I a current density between about 12 and 24 amperes per square foot j for about 15 to 30 minutes. If the anodizing step causes an ¦ undesired cast to be imparted to the anodized surface, a dye ic selected to neutralize that cast.
¦ It is critical to select the dye on the basis of ¦ its ability to neutralize the undesired cast without leaving ¦ a color of its own. Dyes having the color characteristics necessary to neutralize the undesired cast are selected on the ¦ basis of a color system such as the Munsell color system. When ¦ the Munsell system is used, the hue corresponding to the ¦ undesired cast is found on the 100 hue Munsell color circle.
¦ The color opposite the position~on that circle, of said cor- ~
¦ responding hue, i.e. 180 from that position~ is normally the I -¦ neutralizing color. A dye having said neutralizing color then ¦ is selected. Suitable dyes include the monoazo acid metallized l type, among others.
¦ Several dyes may appear to be satisfactory. However, ¦ each dye must be t:ested to determine which dyes of those selected will not leave a color of their own in the anodized surface. ¦ I
Testing may be carried out on a laboratory scale by contacting I samples of anodized aluminum having the undesired cast with aqueou.s I
l sealing solutions containing the individual dyes. (The compos- ¦
¦ ition of said solutions is defined below.) The sealed samples ¦ are visually inspected and the specific dye or dyes that yield ¦ best results are thereby selected.
The specific dye is added in a concentration of between about 3 and 30 milligrams per liter to water, thus making-up the _4_ .
` .
I aqueous sealing solution. Sealing accelerators such as metallic ¦ salts, for example, Co or Ni salts~ can be added to the solution.
¦ The use of accelerators, however, makes color control difficult.
¦ It is critical that the concentration of the dye is below ~he ¦ value that would cause coloring of the anodized surface and is ¦ at or above the value necessary to effect neutralization of the ¦ undesired cast. Minor variations will easily establish the ¦ optimum concentration range for the specific dye. In a ¦ continuous process, the optimum concentration range is maintained .0 ¦ with the aid of a colorimeter or spectrophotometer.
l Also critical to the method of the present invention ¦ is the maintenance of the pH of the solution within a range ¦ that is optimum for sealing and dye absorption. The pH must be ¦ between about 5.5 and 6.5. Selectlon of a pH value is based on ¦ the desired rate of sealing. Sealing rate decreases with ¦ increased acidity. Once a pH value is selected~ it must be I controlled to + 0.1. Sodium hydroxide or acetic acid is used to ¦ control the pH.
¦ The temperature of the solution must be maintained at a ~0 1 value sufficient to effect sealing of the anodized surface. A
l temperature between about 180 and 210F. is selected and I ¦ maintained at + 5F.
¦ Sealing according to the present invention is effected by contacting the anodized aluminum with the dye-containing ~5 1 sealing solution for about lO to 30 minutes.
¦ ~he present invention will be more fully illustrated ¦ in the example which follows:
.
,' ~ .
. - 5 -. ~
EXAMPLE
A high strength aluminum alloy utilized in the manu-facture of bumpers for automobiles was chemically brightened by a conventional process. The alloy had the following composition:
1.0% magnesium, o.8% copper, 4.5~ zinc, less than 0.1~ iron, less than 0.1~ silicon, 0.05~ titanium and the balance; high purity aluminum ingot. Anodizing was effected at a standard current density of 14 amperes per square foot until the anodic coating was between about 0.00~4 and 0.0005 inch thick. The anodized product had an undesired yellow cast. On the basis of the Munsell Color System, five dyes of neutralizing color were selected, namely, aluminum black-c-conc, aluminum grey NL paste, aluminum black 2 LW, aluminum fast black GL paste, and aluminum black V. All dyes were from Sandoz Colors and Chemicals.
A sealing solution having a dye concentration of about 15 milligrams per liter was maintained at a pH between 5.6 and 5.7, with sodium hydroxide and acetic acid. A sealing solution temperature of about 205F. ~ 5F. wa~ used. The anodized alloy was immersed in the solution for 15 minutes. As the result of experimentation w.ith the above-dyes under these conditions, it was found that aluminum black V (also known as acid black 52, a monoazo metallic dye having the chemical formula:
N307SC2oHl 3 xCr Na and a color index of 15,711) successfully neutralized the undesired yellow cast without leaving a color of its own.
Having set forth the general nature and an exemplary embodiment of the present invention, the scope is now par~icu rly pointed out in the appended claims.
~ - 6 -.
Claims (4)
1. A method of neutralizing an undesired cast appearing in an anodized surface of an aluminum alloy, by sealing said anodized surface for about 10 to 30 minutes with an aqueous solution containing a monoazo metallic dye of a color and in a concentration of between 3 and 30 mg. per liter and sufficient to neutralize said undesired cast without imparting the dye color wherein said solution is maintained at a pH between about 5.5 and 6.5 ? 0.1 and a temperature between about 180° and 210°F. ? 5°F.
2. A method as in claim l wherein said aluminum alloy is chemically brightened prior to anodization.
3. A method of neutralizing a yellow cast appearing in an anodized surface of a copper-containing aluminum alloy, by sealing said anodized surface for about 15 minutes in an aqueous solution containing about 15 milligrams per liter of acid black 52, wherein said solution is maintained at a pH
between about 5.6 and 5.7 and a temperature of about 205°F.? 5°F.
between about 5.6 and 5.7 and a temperature of about 205°F.? 5°F.
4. A method as in claim 3 wherein said aluminum alloy is chemically brightened prior to anodizing.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US47411374 US3874902A (en) | 1974-05-28 | 1974-05-28 | Method of neutralizing surface color caused by anodizing aluminum alloys |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1050211A true CA1050211A (en) | 1979-03-13 |
Family
ID=23882228
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA220,999A Expired CA1050211A (en) | 1974-05-28 | 1975-02-28 | Method of neutralizing surface color caused by anodizing aluminum alloys |
Country Status (9)
| Country | Link |
|---|---|
| US (1) | US3874902A (en) |
| JP (1) | JPS5530079B2 (en) |
| BR (1) | BR7501330A (en) |
| CA (1) | CA1050211A (en) |
| DE (1) | DE2510246A1 (en) |
| FR (1) | FR2273088B1 (en) |
| GB (1) | GB1437709A (en) |
| IT (1) | IT1032374B (en) |
| SE (1) | SE7505484L (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3500079A1 (en) * | 1985-01-03 | 1986-07-10 | Henkel KGaA, 4000 Düsseldorf | AGENT AND METHOD FOR PRODUCING COLORLESS COMPRESSION LAYERS ON ANODIZED ALUMINUM SURFACES |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2030236A (en) * | 1933-02-16 | 1936-02-11 | Chem Ind Basel | Colored oxide film of aluminum |
| US2683113A (en) * | 1951-01-16 | 1954-07-06 | Gen Motors Corp | Method of finishing ice trays |
| US2814576A (en) * | 1952-01-30 | 1957-11-26 | Ciba Ltd | Process for producing fast dyeings on anodically oxidized aluminium |
| US2969351A (en) * | 1957-03-11 | 1961-01-24 | Durand & Huguenin Ag | New metalliferous ortho:ortho'-dihydroxy-monoazo-dyestuffs |
| US3767474A (en) * | 1971-09-22 | 1973-10-23 | Cohn S | Sealing methods and compositions for aluminum oxide coatings |
-
1974
- 1974-05-28 US US47411374 patent/US3874902A/en not_active Expired - Lifetime
-
1975
- 1975-02-28 CA CA220,999A patent/CA1050211A/en not_active Expired
- 1975-03-06 BR BR7501330A patent/BR7501330A/en unknown
- 1975-03-08 DE DE19752510246 patent/DE2510246A1/en active Pending
- 1975-03-12 FR FR7507665A patent/FR2273088B1/fr not_active Expired
- 1975-03-18 GB GB1116775A patent/GB1437709A/en not_active Expired
- 1975-03-20 IT IT4868675A patent/IT1032374B/en active
- 1975-04-15 JP JP4575275A patent/JPS5530079B2/ja not_active Expired
- 1975-05-13 SE SE7505484A patent/SE7505484L/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| SE7505484L (en) | 1975-12-01 |
| JPS5530079B2 (en) | 1980-08-08 |
| BR7501330A (en) | 1976-11-30 |
| FR2273088B1 (en) | 1980-04-04 |
| FR2273088A1 (en) | 1975-12-26 |
| DE2510246A1 (en) | 1975-12-18 |
| GB1437709A (en) | 1976-06-03 |
| US3874902A (en) | 1975-04-01 |
| JPS50153738A (en) | 1975-12-11 |
| IT1032374B (en) | 1979-05-30 |
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