KR860008301A - How to prevent corrosion and scale formation in water systems - Google Patents

Abstract

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Description

How to prevent corrosion and scale formation in water systems

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Claims (14)

Precipitation of calcium phosphate or calcium phosphonate on the structural part of the system exposed to the aqueous medium is characterized by the addition of an effective amount of a water soluble polymer containing repeating unit residues of formulas (a) and (b) How to control. In the above formula, R ₁ is H or lower alkyl (C ₁ -C ₃ ); R ₂ is OH, OM or NH ₂ ; M is a water soluble cation; R ₃ is a hydroxy substituted C ₁ to about C ₆ alkyl or alkylene radical, or an unsubstituted C ₁ to about C ₆ alkyl or alkylene radical; X is an anionic radical; Z is H or hydrogen or a water soluble cation or cations, all together offset the valence of X; a is 0 or 1; The method of claim 1, wherein the precipitation of calcium phosphate is controlled on the structural portion of the system exposed to an aqueous medium containing calcium cations and phosphate anions under precipitation forming conditions. The method of claim 1, wherein the precipitation of calcium phosphate on the structural portion of the system exposed to an aqueous medium susceptible to precipitation of calcium phosphate. The process of claim 1, wherein the water soluble polymer contains a third repeating unit residue (c), which repeating unit (c) is acrylic acid, alkyl acrylate, hydroxylated lower alkyl (C ₁ -C). ₆ ) A monomeric repeating unit selected from acrylate, methacrylic acid and acrylamide and water soluble salt forms thereof, wherein the repeating unit (a) and the repeating unit (c) are different from each other. The compound of any of claims 1-4, wherein R ₁ is hydrogen, R ₂ is OH or CM, R ₃ is 2-hydroxypropylidene, X is SO ₃ , Z is one radical or radicals selected from H, Na, NH ₄₊ , Ca and K, and a is 1. 6. The method according to any one of items 1 to 5, wherein the number average molecular weight of the water-soluble polymer is about 1,000 to 1,000,000, the molar ratio x: y is 10: 1 to 1: 5, and the system is a cooling water system. Sufficient amounts of (A) a water-soluble polymer containing repeating unit residues of the following general formulas (a) and (b) and a (B) water-soluble orthophosphate compound, respectively, to provide a passivating oxide film on the metal surface that almost prevents scale formation Forming a protective passivating oxide film on the surface of the metal in contact with the aqueous medium, with little or no precipitation of scale on the iron (II) -containing metal portion in contact with the aqueous medium. A method of suppressing corrosion of the containing metal part. In the above formula, R ₁ is H or lower alkyl (C ₁ -C ₃ ); R ₂ is OH, OM or NH ₂ ; M is a water soluble cation; R ₃ is a hydroxy substituted C ₁ to about C ₆ alkyl or alkylene radical, or an unsubstituted C ₁ to about C ₆ alkyl or alkylene radical; X is an anionic radical; Z is H or hydrogen or a water soluble cation or cations, all together cancel the valence of x; a is 0 or 1; 8. The process of claim 7, wherein the water soluble polymer contains a third repeating unit residue (c), which repeating unit (c) is acrylic acid, alkylacrylate, hydroxylated lower alkyl (C ₁ -C ₆ ) acrylate. , Methacrylic acid and acrylamide and a water-soluble salt thereof, a monomeric repeating unit, provided that the repeating unit (a) and the repeating unit (c) are different from each other. The method according to claim 7 or 8, R ₁ is hydrogen, R ₂ is OH or OMel, R ₃ is 2-hydroxypropylidene, X is SO ₃ , Z is one radical or radicals selected from H, NA, NH ₄₊ , Ca and K, and a is 1. 10. The method of any one of claims 7 to 9, wherein the horizontal group molecular weight of the water-soluble polymer is about 1,000 to 1,000,000, the molar ratio x: y is from 10: 1 to 1: 5 and the aqueous medium is a cooling water system. (A) Mass ratio of the polymer to the orthophosphate represented by PO ₄ ^-3 as the water-soluble polymer containing the repeating unit residue of general formula (a) and (b), and (B) water-soluble orthophosphate compound : 1, wherein the composition comprises a protective, passivating oxide film on the surface of the iron (II) -containing metal portion with little or no precipitation of scale on the iron (II) -containing metal portion in contact with an aqueous solution. In the above formula, R ₁ is H or lower alkyl (C ₁ -C ₃ ); R ₂ is OH, OM or NH ₂ ; M is a water soluble cation; R ₃ is hydroxy substituted C ₁ to about C ₆ alkyl or alkylene radicals, or unsubstituted about C ₁ to C ₆ alkyl or alkylene radicals, X is an anionic radical; Z is H or hydrogen, but is a water soluble cation or cation, all together canceling the valence of X; a is 0 or 1; The method of claim 11, wherein the water soluble polymer contains a third repeating unit residue (c), which repeating unit (c) is acrylic acid, alkyl acrylate, hydroxylated lower alkyl (C ₁ -C ₆ ) acrylate. A monomeric repeating unit selected from methacrylic acid and alkylamide and its water-soluble salt form, provided that the repeating unit (a) and the repeating unit (c) are different from each other. The method of claim 11 or 12, R ₁ is hydrogen, R ₂ is OH or OM, R ₃ is 2-hydroxypropylidene, X is SO ₃ , Z is one radical or radicals selected from H, Na, NH ₄₊ , Ca and K, and a is 1. The composition according to any one of claims 11 to 13, wherein the water-soluble polymer has a number average molecular weight of 1,000 to 1,000,000 and a molar ratio x: y of 10: 1 to 1: 5. ※ Note: The disclosure is based on the initial application.