Classifications

• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
  • C23F11/00—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent
  • C23F11/08—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids
  • C23F11/10—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids using organic inhibitors
  • C23F11/14—Nitrogen-containing compounds
  • C23F11/149—Heterocyclic compounds containing nitrogen as hetero atom

Definitions

• Benzotriazole, mercaptobenzothiazole and tolyltriazole are well known copper corrosion inhibitors.
• U.S. patent 4,675,158 and the references cited therein see U.S. patent 4,744,950, which discloses the use of alkoxybenzotriazoles as corrosion inhibitors and U.S. patent 4,406,811, which discloses the use of benzotriazole/tolyltriazole blends in water treatment compositions for multimetal corrosion inhibition.
• 5-methoxybenzotriazole anisotriazole
• the use of alkoxybenzotriazoles is not known in the water treatment art.
• the instant invention relates to the use of alkoxybenzotriazoles as corrosion inhibitors, particularly copper and copper alloy corrosion inhibitors. These compounds from long-lasting protective films on metallic surfaces, particularly copper and copper alloy surfaces, in contact with aqueous systems.
• the instant invention is directed to a method of inhibiting the corrosion of metallic surfaces, particularly copper and copper alloy surfaces, in contact with an aqueous system, comprising adding to the aqueous system being treated an effective amount of a compound having the following structure: wherein R is any straight or branched, substituted or unsubstituted alkoxy group having 3-18 carbons, and isomers of such compounds.
• the instant invention is also directed to an aqueous system which is in contact with a metallic surface, particularly a copper or copper alloy surface, and which contains an alkoxybenzotriazole.
• compositions comprising water, particularly cooling water, and an alkoxybenzotriazole are also claimed.
• alkoxybenzo­trizoles are effective corrosion inhibitors. These compounds form durable, long-lasting films on metallic surfaces, including but not limited to copper and copper alloy surfaces. Alkoxybenzotriazoles are especially effective inhibitors of copper and copper alloy corrosion, and can be used to protect multimetal systems, especially those containing copper or a copper alloy and one or more other metals.
• alkoxybenzotriazoles de-activate soluble copper ions, which prevents the galvanic deposition of copper which concomminantly occurs with the galvanic dissolution of iron or aluminum in the presence of copper ions. This minimizes aluminum and iron corrosion. These compounds also indirectly limit the above galvanic reaction by preventing the formation of soluble copper ions due to the corrosion of copper and copper alloys.
• Substituted alkoxybenzotriazoles and their isomers can also be used.
• one or more of the CH2 groups in R of structure I when R is an unsubstituted alkoxy group of 3-18 carbons may be replaced by an 0 or NH.
• Specific examples include, but are not limited to, the oxapentyl group (CH3CH2OCH2CH2-), the azapentyl group (CH3CH2NHCH2CH2-) and the 6-oxa-3-aza-octyl group (CH3CH2OCH2CH2 NHCH2CH2-).
• substituted alkoxybenzotriazoles includes compounds wherein R of structure I is any oxa and/or aza alkoxy group. Substituted alkoxybenzotriazoles also include compounds wherein R of structure I contains halogeno­methylene group, CH y X z , where y is 1 or 0 and z is 1 or 2, x is a group VII element, and x can be either the same or a different halogen. Also, one or more of the methylene groups may be substituted with oxygen or sulfur resulting in for example an alcohol, thioalcohol, keto or thioketo group. The carbon of the ether linkage should be unsubstituted.
• Substituted alkoxybenzotriazoles also include compounds wherein R of structure I contains an aromatic group. Particular examples include, but are not limited to, compounds wherein R is: wherein n is 1-9 and X is H, halageno, nitro, carboxy, cyano, amido, substituted amino or C1-C3 alkoxy; and compounds where R is: , wherein n is 1-8, and x is as above.
• an effective amount of an instant alkoxy­benzotriazole should be used.
• the term "effective amount” refers to that amount of an alkoxybenzotriazole which effectively inhibits corrosion in a given aqueous system.
• the alkoxybenzotriazoles, substituted alkoxybenzotriazoles and isomers thereof of the present invention effectively inhibit the corrosion of metallic surfaces, especially copper and copper alloy surfaces, when added to an aqueous system in contact with such surfaces at a concentration of at least about 0.1 ppm, preferably about 0.5 to 100 ppm and most preferably about 1-10 ppm.
• Maximum concentrations are determined by the economic considerations of the particular application, while minimum concentrations are determined by operating conditions such as pH, dissolved solids and temperature.
• the instant alkoxybenzotriazoles may be prepared by any known method.
• the instant alkoxy benzotriazoles may be prepared by contacting a 4-alkoxy-1, 2-diaminobenzene with an aqueous solution of sodium nitrite in the presence of an acid, e.g., sulfuric acid, and then separating the resultant oily product from the aqueous solution.
• the 4-alkoxy-1, 2-diaminobenzene may be obtained from any number of sources.
• the instant compounds can be used as water treatment additives for industrial cooling water systems, gas scrubber systems or any water system which is in contact with a metallic surface, particularly surfaces containing copper and/or copper alloys. They can be fed alone or as part of a treatment package which includes, but is not limited to, biocides, scale inhibitors, dispersants, defoamers and other corrosion inhibitors.
• a treatment package which includes, but is not limited to, biocides, scale inhibitors, dispersants, defoamers and other corrosion inhibitors.
• the instant alkoxybenzotriazoles and substituted alkoxybenzo­triazoles can be fed intermittantly or continuously.
• An object of the instant invention is to provide inhibitors which produce durable protective films, and which overcome the above-described limitations.
• alkoxybenzotriazoles substituted alkoxybenzo­triazoles and isomers of these compunds to minimize corrosion and/or to provide protective, durable hydrophobic films on metallic surfaces, especially copper and copper alloy surfaces.
• the instant alkoxybenzotriazoles allow intermittent feed to cooling water systems. Depending on water aggressiveness, the time between feedings may range from several days to months. This results in an average lower inhibitor requirement and provides advantages relative to waste treatment and environmental impact.
• the preferred alkoxybenzotriazoles are within the range of propyloxybenzotriazole to nonyl­oxybenzotriazole.
• the most preferred compounds are butyloxybenzotriazole, pentoxybenzotriazole and hexyloxybenzotriazole.
• Corrosion results are given in Table III. The results are reported as “Corrosion Rates After Passivation” for the passivation step and as “Corrosion Rates In Inhibitor-Free Agressive Water”.
• Table III shows that 5-pentyloxybenzotriazole provided 99% inhibition, even after 15 days exposure to aggressive water, while the ethyloxybenzotriazole film lasted less than 2 days, and tolyltriazole, a conventional inhibitor, failed within one day.
• the dynamic test unit for these examples consisted of an 8L reservoir, a heater-circulator and a coil heater to provide the desired heat flux.
• the coil heater was designed to fit securely around the 3/8" 0D tubes used in the tests.
• Flow through the tube was monitored by an in-line rotameter having a flow capacity of 400 ml/min.
• the power input to the heater was controlled by a rheostat, which made it possible to vary temperature differences across the tubes.
• the tube inlet and outlet temperatures were monitored by thermocouples attached to a digital readout having an accuracy of 0.1 o F.
• the system was entirely enclosed to minimize evaporation.
• the linear velocity through the heated tubes was 2.2 fps, which gave a N Re of approximately 9350. Heat fluxes of 8,000-10,000 Btu/hr-ft2 were chosen as being representative of industrial practices.
• the corrosion rates of the heated tubes were determined by the weight loss method described in "Standard Practice for Preparing, Cleaning and Evaluating Corrosion Test Specimens"; ASTM designation G1-81.
• the corrosion rates of immersed specimens were determined by linear-polarization using a Petrolite Model M1010 Corrosion Data Acquisition System. This method measures the corrosion rate at a particular time, and is thus useful for following the immediate effects of chlorine concentration on corrosion rates.
• tolyltriazole which is a widely used inhibitor, gave only 36 percent corrosion protection. Also, the immersed copper probes treated with either pentyloxybenzotriazole or hexyloxyl benzotriazole were not significantly affected by exposure to chlorine over the 1 hour contact time while the copper probes treated with tolyltriazole or the blank experienced dramatically higher corrosion rates in the presence of chlorine.
• the pilot cooling tower system used contained two single tube heat exchangers. Cooling water flowed in series through the shell side (annular space) of the heat exchangers and hot water was circulated through the tubes in series, counterflow. In addition to the main recirculation circuit through the cooling tower, the system also contained a recycle loop from the outlet of the No. 2 Heat Exchanger to the inlet of the No. 1 Heat Exchanger for the purpose of maintaining cooling water linear velocity in the heat exchangers.
• the heat exchanger shells were fabricated of Plexiglass to permit observation of the heat exchanger surfaces during the test run. For these tests, a 90/10 copper/nickel tube was placed in the No. 2 Heat Exchanger.
• Instrumentation for monitoring and control of test variables included a pH and conductivity indicator/­controller, PAIR corrosion rate indicators, a temperature indicator/controller, and rotometers for air and water flows.
• PAIR probes for continuous monitoring of 90/10 copper/nickel corrosion rates were installed after the outlet of the No. 2 Heat Exchanger.
• a corrosion test coupon of 90/10 copper/nickel was installed in the recycle loop.
• the PAIR cells and the corrosion test sloop were fabricated of Plexiglass to permit observation of the Corrater electrodes and the corrosion coupons.
• Table VI shows the corrosion rate just prior to the addition of chlorine to the system and the maximum corrosion rate recorded while chlorine was present. Chlorine was added so that between 0.2 mg/L to 0.5 mg/L free residual of chlorine was present. The chlorine concentration was then allowed to dissipate through blow-down, evaporation, and reaction.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Preventing Corrosion Or Incrustation Of Metals (AREA)

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• 1990
  • 1990-04-30 NZ NZ233493A patent/NZ233493A/en unknown
  • 1990-05-07 ZA ZA903436A patent/ZA903436B/xx unknown
  • 1990-05-07 CA CA002016147A patent/CA2016147C/en not_active Expired - Lifetime
  • 1990-05-07 AU AU54760/90A patent/AU636343B2/en not_active Ceased
  • 1990-05-08 JP JP2116998A patent/JP2768538B2/ja not_active Expired - Lifetime
  • 1990-05-08 EP EP90304948A patent/EP0397450B1/de not_active Expired - Lifetime
  • 1990-05-08 DE DE9090304948T patent/DE69000724T2/de not_active Expired - Lifetime
  • 1990-05-08 AT AT90304948T patent/ATE84322T1/de not_active IP Right Cessation
  • 1990-05-08 ES ES90304948T patent/ES2054247T3/es not_active Expired - Lifetime
• 1993
  • 1993-03-05 GR GR930400461T patent/GR3007241T3/el unknown

Non-Patent Citations (3)

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