US3957529A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for cleaning and passivating a metal surface
Assignee: Dow Chemical Co
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Filing: 1974-06-03
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Granted: 1976-05-18
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Expires: 1994-06-03
Abstract
Abstract A cleaning solvent useful in the cleaning of metal surfaces, e.g. nickle-iron alloys, contains sulfamic acid, citric acid, a solvent for hydrocarbon residues, and a surfactant. Metal surfaces are cleaned by contacting the surface with the cleaning solvent and then passivated by contact with aqueous solutions of citric acid or sodium nitrite or a combination of the two.
Inventors
- 👤 George B. Alexander
- 👤 Norman F. Carpenter
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 03:28
CPC Classifications
C; C23; C23G; C23G1/00; C11; C11D; C11D3/00; C11D3/16; C11D3/20; C11D3/2075; C11D3/2086; C11D3/43; C11D7/00; C11D7/02; C11D7/04; C11D7/08; C23G1/02; C23G1/10
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
152 words
A method of cleaning a metal surface which comprises the sequence of steps: a. contacting said surface for a sufficient period of time to clean said surface with a composition comprising in percentages by weight the following ingredients: i. about 8 to 12% sulfamic acid; ii. about 4 to 6% citric acid; iii. about 4 to 6% of a nonionic solvent for hydrocarbon residues which solvent is characterized as not producing turbidity at 75°F when present in said composition; iv. about 0.095 to 0.15% of a soluble nonionic surfactant which surfactant is characterized as having a cloud point of at least about 90°F and having a surface tension of about 32 dynes/cm. or less when present in an amount of 0.1% of said composition; v. the balance, water; b. rinsing said surface with water to remove residual composition; and c. passivating the surface with a solution of citric acid and sodium nitrite.
Claim 2
Independent Claim
152 words
A method of cleaning a metal surface which comprises the sequence of steps: a. contacting said surface for a sufficient period of time to clean said surface with a composition comprising in percentages by weight the following ingredients: i. about 8 to 12% sulfamic acid; ii. about 4 to 6% citric acid; iii. about 4 to 6% of a nonionic solvent for hydrocarbon residues which solvent is characterized as not producing turbidity at 75°F when present in said composition; iv. about 0.095 to 0.15% of a soluble nonionic surfactant which surfactant is characterized as having a cloud point of at least about 90°F and having a surface tension of about 32 dynes/cm. or less when present in an amount of 0.1% of said composition; v. the balance, water; b. rinsing said surface with water to remove residual composition; and c. passivating the surface with a solution of citric acid and sodium nitrite.
Claim 3
Dependent Claim
25 words
The method of claim 1 wherein the flow rate of the composition applied in step (a) is about 2 to about 30 feet per second.
Claim 4
Dependent Claim
21 words
The method of claim 1 wherein the temperature of the composition applied in step (a) is about 40°F to about 140°F.
Claim 5
Dependent Claim
21 words
The method of claim 1 wherein the temperature of the composition applied in step (a) is about 70°F to about 80°F.
Claim 6
Dependent Claim
14 words
The method of claim 1 wherein the surface is that of an iron-nickel alloy.
Claim 7
Dependent Claim
12 words
The method of claim 1 wherein the solvent is a glycol ether.
Claim 8
Dependent Claim
21 words
The method of claim 1 wherein the solvent is chosen from the group consisting of 2-butoxyethanol, 2-(2-butoxyethoxy)ethanol, 2-(2-ethoxyethoxy)ethanol, 2-methoxyethanol, and 2-ethoxyethanol.
Claim 9
Dependent Claim
25 words
The method of claim 1 wherein the surfactant is chosen from the group consisting of linear alcohol ethoxylates, polyoxyethylene esters, and alkyl aryl polyethylene oxides.
Claim 10
Dependent Claim
26 words
The method of claim 1 wherein the surfactant is a mixture of primary alcohols of about 10 to about 12 member carbon chains, about 60% ethoxylated.
Claim 11
Independent Claim
221 words
A method of cleaning an iron-nickel alloy surface which comprises in sequence: a. contacting said surface for a sufficient period of time to clean said surface with a composition comprising in percentages by weight the following ingredients: i. about 8 to 12% sulfamic acid; ii. about 4 to 6% citric acid; iii. about 4 to 6% of a nonionic solvent for hydrocarbon residues which solvent is characterized as not producing turbidity at 75°F when present in said composition; iv. about 0.095 to 0.15% of a soluble nonionic surfactant which surfactant is characterized as having a cloud point of at least about 90°F and having a surface tension of about 32 dynes/cm. or less when present in an amount of 0.1% of said composition; v. the balance, water; at a rate of 4 feet per second for a period of about 2 hours, said composition being maintained at a temperature of about 70°F to 80°F, b. contacting said surface with a 1% aqueous citric acid solution at a rate of 5.5 ft/sec for about 10 minutes, c. contacting said surface with a 0.1% aqueous sodium nitrite solution at a rate of 5.5 ft/sec for about 10 minutes to passivate said surface, and d. contacting said surface with water at a rate of 3.5 ft/sec for about 20 minutes to remove residual substances.
Claim 12
Independent Claim
221 words
A method of cleaning an iron-nickel alloy surface which comprises in sequence: a. contacting said surface for a sufficient period of time to clean said surface with a composition comprising in percentages by weight the following ingredients: i. about 8 to 12% sulfamic acid; ii. about 4 to 6% citric acid; iii. about 4 to 6% of a nonionic solvent for hydrocarbon residues which solvent is characterized as not producing turbidity at 75°F when present in said composition; iv. about 0.095 to 0.15% of a soluble nonionic surfactant which surfactant is characterized as having a cloud point of at least about 90°F and having a surface tension of about 32 dynes/cm. or less when present in an amount of 0.1% of said composition; v. the balance, water; at a rate of 4 feet per second for a period of about 2 hours, said composition being maintained at a temperature of about 70°F to 80°F, b. contacting said surface with a 1% aqueous citric acid solution at a rate of 5.5 ft/sec for about 10 minutes, c. contacting said surface with a 0.1% aqueous sodium nitrite solution at a rate of 5.5 ft/sec for about 10 minutes to passivate said surface, and d. contacting said surface with water at a rate of 3.5 ft/sec for about 20 minutes to remove residual substances.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-05-18 | 1979-11-17 | 1980-05-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-05-18 | 1983-11-17 | 1984-05-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-05-18 | 1987-11-17 | 1988-05-18 | $7700.00 | Window Closed / Lapsed |