JPS6259640B2 - - 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 to 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 excellent phosphorus-free or low-phosphorus scale prevention that suppresses scale generation even when used in combination with known corrosion inhibitors such as zinc-based and condensed phosphoric acid-based corrosion inhibitors. That is, the scale inhibitor of the present invention has the general formula: (However, in the formula, R ¹ represents hydrogen or a methyl group, and X represents hydrogen, a monovalent metal, a divalent metal, an ammonium group, or an organic amine group.) Seed (meth)acrylic acid monomer (),
general formula (However, in the formula, p represents an integer of 1 to 4, q and r each independently represent an integer of 0 or 1 to 100, and R ² and R ³ each independently represent an integer of 2 to 4 carbon atoms.
represents an alkylene group, and Y and Z each independently represent a hydroxyl group, an alkoxyl group having 1 to 4 carbon atoms, 1
A monovalent phosphoric acid group (including salts of monovalent metals, divalent metals, ammonium groups, or organic amine groups, or mono- or diesters of alkyl groups having 1 to 4 carbon atoms) or a monovalent sulfonic acid group (however, , a monovalent metal, a divalent metal, an ammonium salt or a salt of an organic amine group, 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 Represents a divalent sulfonic acid group. ) At least one allyl ether monomer selected from the group consisting of compounds represented by (), and a monomer copolymerizable with these monomers ()
, (meth)acrylic acid monomer ()20~99.5
Mol%, allyl ether monomer () 0.5-80
Mol% and monomer () 0 to 40 mol% (however,
The sum of (), () and () is 100 mol%. ) is the main component. Examples of the (meth)acrylic acid monomer () used in the present invention include acrylic acid, sodium acrylate, potassium acrylate, lithium acrylate, ammonium acrylate, methacrylic acid, sodium methacrylate, potassium methacrylate, Examples include lithium methacrylate and ammonium methacrylate. In addition, as the allyl ether monomer (), for example,
3-allyloxypropane-1,2-diol, 3
-Allyloxypropane-1,2-diol phosphate, 3-allyloxypropane-1,2-diol sulfonate, 3-allyloxy-1,2-di(poly)oxyethylene ether propane, 3-
Allyloxy-1,2-di(poly)oxyethylene ether propane phosphate, 3-allyloxy-1,2-di(poly)oxyethylene ether propane sulfonate, 3-allyloxy-1,2
-di(poly)oxypropylene ether propane, 3-allyloxy-1,2-di(poly)oxypropylene ether propane phosphate, 3-
Allyloxy-1,2-di(poly)oxypropylene ether propane sulfonate, 6-allyloxyhexane 1,2,3,4,5-pentaol,
6-allyloxyhexane-1,2,3,4,5-
Pentaol phosphate, 6-allyloxyhexane-1,2,3,4,5-pentaol sulfonate, 6-allyloxy-1,2,3,4,5-
Penta(poly)oxyethylene ether hexane, 6-allyloxy-1,2,3,4,5-penta(polyoxypropylene ether hexane, 3
-Allyloxy-2-hydroxypropanesulfonic acid and its monovalent metal salts, divalent metal salts, ammonium salts or organic amine salts, or phosphoric acid esters or sulfuric acid esters of these compounds and their monovalent metal salts, 2 Valent metal salt, ammonium salt or organic amine salt; 3-allyloxy-2-(poly)
Oxyethylenepropanesulfonic acid and its monovalent metal salts, divalent metal salts, ammonium salts or organic amine salts, or phosphoric acid esters or sulfuric acid esters of these compounds, and their monovalent metal salts, divalent metal salts, Ammonium salt or organic amine salt; 3-allyloxy-2-(poly)oxypropylenepropanesulfonic acid and its monovalent metal salt, 2
Examples include valent metal salts, ammonium salts, or organic amine salts, or phosphoric acid esters or sulfuric acid esters of these compounds, and monovalent metal salts, divalent metal salts, ammonium salts, or organic amine salts thereof; . Among these allyl ether monomers (), those in which p in the general formula is 1 or 4 are advantageous because they are easily available industrially. The usage amounts of (meth)acrylic acid monomer () and allyl ether monomer () are as follows: (meth)acrylic acid monomer (), allyl ether monomer () and monomer ( ) respectively in amounts of 20 to 99.5 mol% and 0.5 to 80 mol%. Even if either the (meth)acrylic acid monomer () or the allyl ether monomer () is out of the above range, the excellent scale inhibitor of the present invention cannot be obtained. The monomer () may be selected based on the total of the (meth)acrylic acid monomer (), the allyl ether monomer (), and the monomer () so that the resulting polymer is water-soluble. Such monomers () may be used in amounts of up to 40 mol% within the range
For example, styrene, vinyl acetate, (meth)acrylonitrile, (meth)acrylamide, methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate,
Examples include dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, maleic acid, fumaric acid, itaconic acid, and monovalent metal salts, divalent metal salts, ammonium salts or organic amine groups of these acids. can. A conventionally known method can be used to obtain the copolymer (A) from the (meth)acrylic acid monomer (), the allyl ether monomer (), and the monomer (). 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 a water-soluble organic solvent and water, an appropriate polymerization initiator or a combination of a polymerization initiator and an accelerator can be selected from among the various polymerization initiators described above. 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. Such alkaline substances include 1
Examples include hydroxides, chlorides and carbonates of valent metals and divalent metals; ammonia; organic amines and the like. As the scale inhibitor of the present invention, copolymer (A)
Although it is sufficiently effective when used alone, it can also be used in combination with other additives used in the art. 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 effect is 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 specified, all parts are by weight, and all percentages are by weight. Reference Example 1 Put 165 g of pure water into a 4-necked flask with an inner volume of 1 and equipped with a reflux condenser, and add 620 g of a 30% aqueous solution of sodium acrylate and 15 g of 3-allyloxy-1,2-dihydroxypropane while stirring at 90°C. ,
200 g of a 5% aqueous solution of ammonium persulfate and ammonium persulfate were each added dropwise over 3.5 hours to cause a copolymerization reaction to obtain a pale yellow and transparent reaction solution. When the unreacted monomer was measured by the bromine addition method (the same applies to the following examples), the polymerization rate was 95%. The number average molecular weight of this water-soluble copolymer (1) measured by gel permeation chromatography (the same applies to the following examples) is
It was 4400. Furthermore, infrared absorption spectrum analysis of this water-soluble copolymer (1), which was purified by precipitation with methanol and dried, confirmed absorption based on -O-, -CO-, and -OH. Furthermore, this dried water-soluble copolymer (1) was dissolved in D ₂ O and subjected to NM analysis.

Absorption of [formula] and -CH ₂ - was confirmed. Reference Example 2 Using the polymerization reactor used in Reference Example 1, pure water
191g, 437g of 30% potassium methacrylate aqueous solution,
172 g of a 40% aqueous solution of 3-allyloxy-1,2-dihydroxypropane phosphate obtained by reacting an equivalent amount of 3-allyloxy-1,2-dihydroxypropane with phosphorus pentoxide, and 200 g of a 6% aqueous solution of ammonium persulfate. A polymerization reaction was carried out in the same manner as in Reference Example 1 except that a yellow transparent aqueous solution of water-soluble copolymer (2) was obtained. The weight percentage is 85%,
The number average molecular weight of water-soluble copolymer (2) was 6,100. Reference Example 3 Using the polymerization reactor used in Reference Example 1, pure water
249g, 35% aqueous solution of sodium acrylate 406
A polymerization reaction was carried out in the same manner as in Reference Example 2 except that 145 g of a 40% aqueous solution of sodium 3-allyloxy-2-hydroxypropanesulfonate was used to obtain a red and transparent water-soluble copolymer (3) aqueous solution. .
The polymerization rate was 94%, and the number average molecular weight of water-soluble copolymer (3) was 4,900. Reference Example 4 Using the polymerization reactor used in Reference Example 1, pure water
After preparing 370g, 3-allyloxy-1,2
-Dissolve 100 g of allyl ether monomer obtained by adding 10 moles of ethylene oxide to dihydroxypropane using powdered sodium hydroxide as a catalyst, and then dissolve in a 30% aqueous potassium methacrylate solution.
A polymerization reaction was carried out in the same manner as in Reference Example 2 except that 330 g was added dropwise over 3.5 hours to obtain a reddish-brown transparent aqueous solution of water-soluble copolymer (4). The polymerization rate was 90%, and the number average molecular weight of water-soluble copolymer (4) was 6,500. Reference Example 5 Using the polymerization reactor used in Reference Example 1, pure water
422g of 35% aqueous solution of 248g sodium acrylate,
Reference example except that 130 g of a 40% aqueous solution of an allyl ether monomer obtained by adding 2 moles of propylene oxide to 3-allyloxy-1,2-dihydroxypropane and then reacting an equivalent amount of phosphorus pentoxide was used. A polymerization reaction was carried out in the same manner as in 2 to obtain a yellow and transparent aqueous solution of water-soluble copolymer (5). The polymerization rate was 95%, and the number average molecular weight of water-soluble copolymer (5) was 4,500. Reference Example 6 Using the polymerization reactor used in Reference Example 1, pure water
240g, 520g of 35% sodium acrylate aqueous solution,
and a 20% aqueous solution of sodium hydroxide as a catalyst.
A polymerization reaction was carried out in the same manner as in Reference Example 1, except that 40 g of a 50% aqueous solution of monoallyl sorbitol ether separated from the reaction solution obtained by reacting the same mole of allyl bromide and sorbitol at 75°C was used to produce a yellow transparent water-soluble copolymer. An aqueous solution of coalescence (6) was obtained. Polymerization rate is 97%
The number average molecular weight of water-soluble copolymer (6) was 4,400. Reference Example 7 Using the polymerization reactor used in Reference Example 1, pure water
After 400 g of disodium maleate was added with stirring, the temperature was raised to 100°C and dissolved. Then a 35% aqueous solution of sodium acrylate
250g of sodium 3-allyloxy-2-hydroxypropanesulfonate, 85g of a 60% aqueous solution of sodium 3-allyloxy-2-hydroxypropanesulfonate, 100g of a 6% aqueous solution of ammonium persulfate, and 100g of a 6% aqueous solution of hydrogen peroxide were each added dropwise over 4 hours to cause a copolymerization reaction. An aqueous solution of copolymer (7) was obtained. The polymerization rate was 92%, and the number average molecular weight of the water-soluble copolymer (7) was 4,100. Examples 1 to 6 Put 170 g of water into a 225 ml glass bottle, add 10 g of calcium chloride dihydrate 1.56% aqueous solution, and Reference Example (1)
Each of the water-soluble copolymers (1) to (6) obtained in ~(6)
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 K 0101. 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.

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[Table] Examples 7 to 13 Calcium chloride dihydrate in a 225ml glass bottle
Add 145g of 45.6% aqueous solution, then reference examples (1) to (7)
0.02% of each of the water-soluble copolymers (1) to (7) obtained in
Mix 5g, 30g or 50g of the aqueous solution (5ppm, 30ppm or 50ppm based on the resulting test aqueous solution) and add an appropriate sodium hydroxide aqueous solution to the pH.
10.0, and water was added to make the total amount 200 g, which was used as an aqueous solution for testing. This was stored at 20° C. for 30 days, and the precipitate was filtered through a 0.1μ membrane filter, and after drying, the weight of the precipitate was measured. The results are shown in Table 2. Comparative Example 4 Example 7 was repeated except that sodium polyacrylate having a molecular weight of 4000 was used instead of the water-soluble copolymer used in Example 7. The results are shown in Table 2. Comparative Example 5 Example 7 was repeated except that sodium hexametaphosphate was used instead of the water-soluble copolymer used in Example 7. The results are shown in Table 2. Comparative Example 6 Example 7 was repeated except that the water 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, R ¹ represents hydrogen or a methyl group, and X represents hydrogen, a monovalent metal, a divalent metal, an ammonium group, or an organic amine group.) Seed (meth)acrylic acid monomer (), general formula (However, in the formula, p represents an integer of 1 to 4, q and r each independently represent an integer of 0 or 1 to 100, and R ² and R ³ each independently represent an integer of 2 to 4 carbon atoms.
represents an alkylene group, and Y and Z each independently represent a hydroxyl group, an alkoxyl group having 1 to 4 carbon atoms, 1
A monovalent phosphoric acid group (including salts of monovalent metals, divalent metals, ammonium groups, or organic amine groups, or mono- or diesters of alkyl groups having 1 to 4 carbon atoms) or a monovalent sulfonic acid group (however, , a monovalent metal, a divalent metal, an ammonium salt or a salt of an organic amine group, 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 Represents a divalent sulfonic acid group. ) At least one allyl ether monomer selected from the group consisting of compounds represented by () and a monomer copolymerizable with these monomers ()
, (meth)acrylic acid monomer ()20~99.5
Mol%, allyl ether monomer () 0.5-80
Mol% and monomer () 0 to 40 mol% (however,
The sum of (), () and () is 100 mol%. ) A scale inhibitor whose main component is a copolymer (A) derived by using the following ratio.