JPS6223639B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to scale inhibitors.
Specifically, it relates to a scale inhibitor used in boilers, condensers, heat exchangers, gas scrubbing towers, etc. The heat transfer surfaces of boilers, condensers, heat exchangers, etc., the filling surfaces and piping of gas scrubbing towers, etc., contain cations such as calcium and magnesium, carbonate ions, etc. present in make-up water, cooling water, and collection water. bicarbonate ion,
In addition to anions such as sulfite ions and sulfate ions,
In some cases, zinc ions and phosphate ions caused by corrosion inhibitors are likely to precipitate and form scale. This phenomenon is particularly noticeable in systems that use a refrigerant with a high Ca concentration and high pH, so-called brine. Such scale adhesion not only increases operating costs due to decreased heat transfer efficiency and increased flow resistance, but also
Scale adhesion on the sensors of various instruments such as meters can lead to abnormal readings and delays in response speed.
Furthermore, localized corrosion makes it difficult to continue normal operation. Since the attached scale is hard and difficult to remove, the cost required for stopping the operation, removing the scale, etc. is also large. Conventionally, lignin-based compounds, phosphorus-based compounds, poly(meth)acrylates, and the like have been used as scale inhibitors for the purpose of preventing such scale adhesion. However, the quality of lignin-based compounds is not constant, and as mentioned above, hydrolyzed phosphate ions, including those added as corrosion inhibitors, become scale components when highly concentrated, and furthermore, they are included in blow water. If they are released into closed water systems such as lakes and inland seas, they can cause serious pollution such as blue-green algae and red tide. Although poly(meth)acrylate has received the best evaluation among these conventionally used scale inhibitors, it still tends to generate zinc-based, phosphorus-based, etc. scales when highly concentrated. An object of the present invention is to provide an excellent phosphorus-free or low-phosphorus scale inhibitor that suppresses scale generation even when used in combination with known corrosion inhibitors such as zinc-based and condensed phosphate-based corrosion inhibitors. That is, the scale inhibitor of the present invention has the general formula: (However, in the formula, A ¹ and A ² each independently represent hydrogen, a methyl group, or -COOX ² , and A ¹ and A ² cannot be -COOX ² at the same time, and A ³ represents hydrogen, a methyl group, or -COOX 2. represents CH ₂ −COOX ³ and when A ³ is −CH ₂ −COOX ³ , A ¹ and
A ² each independently represents hydrogen or a methyl group, and X ¹ , X ² and X ³ each independently or together represent hydrogen, a monovalent metal, a divalent metal, an ammonium group or an organic amine group. ) One or more unsaturated carboxylic acid monomers () represented by the general formula (However, in the formula, p and q are each independently 0 or 1 to
represents an integer of 100, R ¹ represents hydrogen or a methyl group, R ² represents an alkylene group having 1 to 4 carbon atoms, R ³ and R ⁴ each independently represent an alkylene group having 2 to 4 carbon atoms, Y and Z are each independently a hydroxyl group, carbon number 1-
4 alkoxy group, monovalent phosphoric acid group (including salts of monovalent metals, divalent metals, ammonia or organic amine groups, or mono- or diesters of alkyl groups having 1 to 4 carbon atoms), monovalent phosphoric acid groups A sulfonic acid group (including salts of monovalent metals, divalent metals, ammonia or organic amine groups, or esters of alkyl groups having 1 to 4 carbon atoms) or a monovalent sulfuric acid group (including monovalent metals, divalent metals, salts of ammonia or organic amine groups, or esters of alkyl groups having 1 to 4 carbon atoms); or Y and Z together represent a divalent phosphoric acid group or a divalent sulfonic acid group. represents. ) One or more selected from the (meth)acrylic acid ester monomers () shown in () and a monomer copolymerizable with these monomers ()
, unsaturated carboxylic acid monomer () 10 to 99.5 mol%, (meth)acrylic acid ester monomer () 0.5 to 90 mol%, and monomer () 0 to 40 mol% (However, ( ), (), and () are 100 mol % in total. Examples of the unsaturated carboxylic acid monomer () used in the present invention include acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, monovalent metals such as Examples include partially neutralized products or completely neutralized products with metals, ammonia, and organic amines. Examples of monovalent metals include sodium and potassium, and examples of divalent metals include calcium, magnesium, and zinc. In addition, organic amines include alkylamines such as monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, and triethylamine; alkanolamines such as monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, and dimethylethanolamine; and pyridine. etc. can be given. Further, as the (meth)acrylic acid ester monomer () represented by the above general formula, for example, 3-
(meth)acryloxy-1,2-dihydroxypropane; 3-(meth)acryloxy-1,2-di(poly)oxyethylene ether propane; 3-
(meth)acryloxy-1,2-di(poly)oxypropylene ether propane; 3-(meth)acryloxy-1,2-dihydroxypropane phosphate and its monovalent metal, divalent metal, ammonium salt, organic amine salt or Mono- or diester of alkyl group having 1 to 4 carbon atoms; 3-(meth)
Acryloxy-1,2-dihydroxypropane sulfate and its monovalent metal salt, divalent metal salt, ammonium salt, organic amine salt or carbon number 1-4
3-(meth)acryloxy-2-hydroxypropanesulfonic acid and its monovalent metal salt, divalent metal salt, ammonium salt, organic amine salt or ester of an alkyl group having 1 to 4 carbon atoms; 3 -(meth)acryloxy-2-(poly)
Oxyethylene ether propane sulfonic acid and its monovalent metal salts, divalent metal salts, ammonium salts,
Organic amine salts or esters of alkyl groups having 1 to 4 carbon atoms; 3-(meth)acryloxy-2-(poly)oxypropylene ether propanesulfonic acid and its monovalent metal salts, divalent metal salts, ammonium salts, organic amines Examples include salts and esters of alkyl groups having 1 to 4 carbon atoms. The monomer () is a water-soluble polymer obtained based on the total of the unsaturated carboxylic acid monomer (), the (meth)acrylic acid ester monomer (), and the monomer () as necessary. Examples of such monomers include styrene, styrene sulfonic acid, vinyl acetate (meth)acrylonitrile,
Examples include (meth)acrylamide, methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, etc. can. Unsaturated carboxylic acid monomers () and (meta)
The amount of acrylic ester monomer () used is:
10-99.5 mol% and 0.5-99.5 mol% respectively based on the total of unsaturated carboxylic acid monomer (), (meth)acrylic acid ester monomer () and monomer ()
The amount is 90 mol%. Even if either the unsaturated carboxylic acid monomer () or the (meth)acrylic acid ester monomer () deviates from the above range, the excellent scale inhibitor of the present invention cannot be obtained. Unsaturated carboxylic acid monomer (), (meth)acrylic acid ester monomer () and monomer ()
Copolymer (A) can be obtained by conventionally known methods. Examples include polymerization in a solvent such as water, an organic solvent, or a mixed solvent of a water-soluble organic solvent and water. At this time, persulfate, hydrogen peroxide, etc. are used as a polymerization initiator for polymerization in an aqueous medium, and a promoter such as sodium bisulfite or ascorbic acid may be used in combination. For polymerization in an organic solvent, an azo compound, an organic peroxide, or the like is used as a polymerization initiator, and a promoter such as an amine compound can be used in combination. For polymerization in a mixed solvent of water-soluble organic solvent and water,
The polymerization initiator or the combination of the polymerization initiator and the accelerator can be appropriately selected from among the above-mentioned various polymerization initiators or combinations of the polymerization initiator and accelerator. The copolymer (A) thus obtained can be used as a scale inhibitor as it is, but if necessary, it can be further neutralized with an alkaline substance before use. Examples of such alkaline substances include hydroxides, chlorides, and carbonates of monovalent metals and divalent metals; ammonia; organic amines, and the like. As the scale inhibitor of the present invention, copolymer (A) is sufficiently effective when used alone, but it can also be used in combination with other additives used in the technical field. For example, it can be combined with a phosphorus-free corrosion inhibitor such as molybdenum to form a phosphorus-free water treatment composition. It is also possible to use a slime inhibitor or chelating agent in combination, if necessary. The scale inhibitor of the present invention can be used in the same manner as ordinary scale inhibitors, for example, by quantitative injection or intermittent injection so that the concentration in circulating water is constant, and the amount added is generally 1.
Sufficient effects are observed at ~50ppm. Hereinafter, the present invention will be explained in more detail with reference to Reference Examples and Examples. In the examples, unless otherwise noted,
All parts are by weight, and all percentages are by weight. Reference Example 1 325 g of pure water was charged into a 4-necked flask with an internal volume of 1 equipped with a reflux condenser, and while stirring at 90°C, 420 g of a 30% aqueous solution of sodium acrylate, 55 g of 3-methacryloxy-1,2-dihydroxypropane was added.
g and 100 g of a 5% aqueous solution of ammonium persulfate were each added dropwise over 4 hours to cause a copolymerization reaction.
When the unreacted monomer was measured by the bromine addition method (the same applies to the following examples), the polymerization rate was 97%. In addition, the number average molecular weight of this water-soluble copolymer (1) obtained by precipitation purification with methanol and drying was 4500, and infrared absorption spectroscopy revealed -CO-, -
Absorption based on OH was confirmed. Furthermore, the water-soluble copolymer (1) obtained by drying was dissolved in D ₂ O,
NMR analysis,

[Formula] Absorption of -CH ₂ - and -CH ₃ was confirmed. Reference Example 2 Using the same polymerization reactor as Reference Example 1, pure water 310
After adding 50 g of dipotassium maleate, add 370 g of a 30% aqueous solution of potassium methacrylate and 3-acryloxy-1,2 while stirring at 95℃.
-20 g of dihydroxypropane, 100 g of a 10% aqueous solution of ammonium persulfate, and 50 g of a 10% aqueous solution of hydrogen peroxide were each added dropwise over 4 hours to cause a copolymerization reaction. The polymerization rate was 95%. The number average molecular weight of this water-soluble copolymer (2) was 3,900. Reference example 3 Using the same polymerization reactor as in reference example 1, pure water 250
g and 35% aqueous solution of sodium acrylate.
400 g of a 50% aqueous solution of sodium 3-methacryloxy-2-hydroxypropanesulfonate and 100 g of a 3% aqueous solution of ammonium persulfate were each added dropwise over 4 hours to cause a copolymerization reaction. The polymerization rate was 97%. The number average molecular weight of this water-soluble copolymer (3) was 4,800. Examples 1 to 3 Put 170 g of water in a glass bottle with a capacity of 225 ml, add 10 g of a 1.56% aqueous solution of calcium chloride dihydrate, and Reference Example (1).
Each of the water-soluble copolymers (1) to (3) obtained in ~(3)
1g, 5g or 10g of 0.02% aqueous solution (1ppm, 5ppm or 10ppm based on the resulting supersaturated aqueous solution)
Mix and add 10g of 3% sodium bicarbonate solution
Calcium carbonate obtained by adding and mixing
A 530 ppm supersaturated aqueous solution was sealed and heat treated at 70°C for 3 hours. Then, after cooling, the precipitate
Filter the liquid through a 0.45μ membrane filter.
Analyzed according to JIS K0101. The results are shown in Table 1. Comparative Example 1 Example 1 was repeated except that sodium polyacrylate having a molecular weight of 4000 was used instead of the water-soluble copolymer used in Example 1. The results are shown in Table 1. Comparative Example 2 Example 1 except that sodium tripolyphosphate was used instead of the water-soluble copolymer used in Example 1.
repeated. The results are shown in Table 1. Comparative Example 3 Example 1 was repeated except that the water-soluble copolymer was not added. The results are shown in Table 1. Examples 4-6 Calcium chloride dihydrate in a 225ml glass bottle
Add 145g of 45.6% water solubility, then reference examples (1) to (3)
0.02% of each of the water-soluble copolymers (1) to (3) obtained in
Mix 5 g, 30 g or 50 g of the aqueous solution (5 ppm, 30 ppm or 50 ppm based on the obtained test aqueous solution), and further add an aqueous sodium hydroxide solution as appropriate.
The pH was adjusted to 10.0, water was added to make the total amount 200 g, and an aqueous solution for testing was prepared. Store this at 20℃ for 30 days,
Filter the precipitate through a 0.1μ membrane filter,
The weight of the dried precipitate was measured. The results are shown in Table 2. Comparative Example 4 Example 4 was repeated except that sodium polyacrylate having a molecular weight of 4000 was used instead of the water-soluble copolymer used in Example 4. The results are shown in Table 2. Comparative Example 5 Example 4 was repeated except that sodium hexametaphosphate was used instead of the water-soluble copolymer used in Example 4. The results are shown in Table 2. Comparative Example 6 Example 4 was repeated except that the water-soluble copolymer was not added. The results are shown in Table 2.

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Claims (1)

[Claims] 1. General formula (However, in the formula, A ¹ and A ² each independently represent hydrogen, a methyl group, or -COOX ² , and A ¹ and A ² cannot be -COOX ² at the same time, and A ³ represents hydrogen, a methyl group, or -COOX 2. represents CH ₂ −COOX ³ and when A ³ is −CH ₂ −COOX ³ , A ¹ and
A ² each independently represents hydrogen or a methyl group, and X ¹ , X ² and X ³ each independently or together represent hydrogen, a monovalent metal, a divalent metal, an ammonium group or an organic amine group. ) One or more unsaturated carboxylic acid monomers () represented by the general formula (However, in the formula, p and q are each independently 0 or 1.
represents an integer of ~100, R ¹ represents hydrogen or a methyl group, R ² represents an alkylene group having 1 to 4 carbon atoms, and R ³ and R ⁴ each independently represent an alkylene group having 2 to 4 carbon atoms. , Y and Z are each independently a hydroxyl group, a carbon number of 1 to
4 alkoxy group, monovalent phosphoric acid group (including monovalent metal, divalent metal, salt of ammonia or organic amine, or mono- or diester of alkyl group having 1 to 4 carbon atoms), monovalent sulfone Acid groups (including monovalent metals, divalent metals, salts of ammonia or organic amines, or esters of alkyl groups having 1 to 4 carbon atoms) or monovalent sulfate groups (however, monovalent metals, divalent metals) , ammonia or an organic amine salt, or an ester of an alkyl group having 1 to 4 carbon atoms), or Y and Z together represent a divalent phosphoric acid group or a divalent sulfonic acid group. ) One or more selected from the (meth)acrylic acid ester monomers () shown in () and a monomer copolymerizable with these monomers ()
, unsaturated carboxylic acid monomer () 10 to 99.5 mol%, (meth)acrylic acid ester monomer () 0.5 to 90 mol%, and monomer () 0 to 40 mol% (However, ( ), the sum of () and () is 100 mol%.