JPH0475800B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to scale inhibitors.
More specifically, it relates to scale inhibitors used in boilers, condensers, heat exchangers, gas scrubbing towers, geothermal power generation, and the like. 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 abnormal readings due to scale adhesion to the sensors of various instruments such as thermometers and PH meters. This causes a delay 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 tidal marshes or 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. In order to improve these above-mentioned drawbacks, for example,
No. 51-146341, JP-A-59-25809, JP-A-59-
Copolymers using (meth)acrylic acid ester monomers having hydroxyl groups have been proposed in No. 196799, but these copolymers have ester bonds and are therefore susceptible to hydrolysis. for example
It was unsuitable for use in relatively high-temperature systems such as cooling water systems, boilers, and geothermal power generation systems where temperatures exceed 70°C. Additionally, JP-A-59-102496 proposes the use of _C5 unsaturated alcohol, which has received relatively good reviews, but is said to be vulnerable to water conditions with high concentrations of scale components such as zinc and phosphorus. There were flaws. Also, Special Publication No. 57-39246, Japanese Patent Publication No. 56-111098
No., JP-A-57-84794, JP-A-57-119896,
JP-A-57-126810, JP-A-57-144094, JP-A-57-202311, JP-A-59-391, JP-A-59-
No. 12798, JP-A-59-12908, JP-A-59-176312
The use of allyl alcohol or unsaturated alcoholic monomers in which ethylene oxide or propylene oxide is added to allyl alcohol has been proposed in Japanese Patent Application Laid-Open No. 59-22698, but these monomers have a basic skeleton. Since it is an allyl group, copolymerization with unsaturated monocarboxylic acid and/or unsaturated dicarboxylic acid is not sufficient, and when used as a scale inhibitor, a relatively large amount is required, which is not preferable. As a result of intensive research in view of the current situation, the present inventors have found that unsaturated alcoholic monomers obtained by adding alkylene oxide to specific alcohols can form unsaturated monocarboxylic acids and/or unsaturated dicarboxylic acids. We have discovered that the copolymer obtained by copolymerization is resistant to hydrolysis and has much better scale prevention performance than the above-mentioned known (co)polymers. The present invention has been completed. That is, the present invention has the general formula (However, in the formula, A ¹ and A ² are each independently hydrogen,
Represents a methyl group or -COOX ² , and A ¹ and A ² cannot be -COOX ² at the same time, A ³ is hydrogen,
represents a methyl group or -CH ₂ COOX ³ and A ³ is -
In the case of CH ₂ COOX ³ , A ¹ and A ² each independently represent 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, or an ammonium group. group or organic amine group. ) One or more unsaturated carboxylic acid monomers () represented by the general formula (However, in the formula, R ¹ and R ² each independently represent hydrogen or a methyl group, R ¹ and R ² cannot be a methyl group at the same time, and R ³ is -CH ₂ -, -
(CH ₂ ) ₂ - or -C(CH ₃ ) ₂ - and R ¹ , R ²
The total number of carbon atoms in and R ³ is 3, Y represents an alkylene group having 2 to 3 carbon atoms, and n is an integer of 1 to 100. ) One or more selected from the unsaturated alcoholic monomers () shown in 40 to 99.5 mol% of the unsaturated carboxylic acid monomer () and 0.5% of the unsaturated alcoholic monomer () ~60 mol% (however, the total of () and () is 100 mol%
It is. The present invention relates to a scale inhibitor containing a copolymer (A) as a main component, which is obtained by using the following ratio. Examples of the unsaturated carboxylic acid monomer () represented by the above general formula used in the present invention include:
Partially or completely neutralized products of acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, or other acids with monovalent metals, divalent metals, ammonia, and organic amines are listed. It will be done. Monovalent metals include sodium, potassium, etc., and divalent metals include:
Examples include calcium, magnesium, and zinc. In addition, organic amines include alkylamines such as monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, and triethylamine; monoethanolamine,
Examples include alkanolamines such as diethanolamine, triethanolamine, monoisopropanolamine, and dimethylethanolamine; pyridine; and the like. Further, as the unsaturated alcohol monomer () represented by the above general formula, for example, 3-methyl-3
- From 1 to 1 mol of ethylene oxide and/or propylene oxide per mol of unsaturated alcohol such as buten-1-ol, 3-methyl-2-buten-1-ol, 2-methyl-3-buten-2-ol, etc. Compounds with 100 moles added can be mentioned. The types of ethylene oxide and propylene oxide may be one or two types, and
When adding multiple types, there are no restrictions on the order in which they are combined. If the number of moles of alkylene oxide added is 0 moles, the effect of the present invention is not sufficient, and even if the amount exceeds 100 moles, no improvement in the effect is observed, and on the contrary, a large amount of addition is required, which is not preferable. . The amount of unsaturated carboxylic acid monomer () and unsaturated alcohol monomer () used is based on the total amount of unsaturated carboxylic acid monomer () and unsaturated alcohol monomer (). , 40 to 99.5 respectively
mol%, 0.5 to 60 mol%. Even if either the unsaturated carboxylic acid monomer () or the unsaturated alcohol monomer () is out of the above range, the excellent scale inhibitor of the present invention cannot be obtained. The copolymer (A) can be obtained from the unsaturated carboxylic acid monomer () and the unsaturated alcohol monomer () by a conventionally known method. for example,
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 it is as the scale inhibitor of the present invention, but if necessary, it can be further neutralized with an alkaline substance before use. Examples of such alkaline substances include hydroxides, chlorides, carbonates, and bicarbonates of monovalent 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 effects are observed at ~50ppm. EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to these examples. In the examples, % represents weight % unless otherwise specified. Reference Example 1 Put 451 g of ion-exchanged water into a 5-neck round bottom flask with a capacity of 1.5 and equipped with a reflux condenser, raise the temperature to 75°C, and add 195 g of 40% ammonium acrylate aqueous solution (as ammonium acrylate) while stirring.
0.876 mol), 33 g of 80% acrylic acid aqueous solution (0.366 mol as acrylic acid), unsaturated alcohol made by adding 5 mol of ethylene oxide to 3-methyl-3-buten-1-ol (hereinafter referred to as IEO-5).
191g of 50% aqueous solution (0.312mol as IEO-5)
and 130 g of a 3% ammonium persulfate aqueous solution were each dropped from separate dropping nozzles. In addition, the dropping time was 150 minutes for the ammonium persulfate aqueous solution, and for the others.
It was set as 120 minutes. After dropping the ammonium persulfate aqueous solution, the copolymerization reaction was continued at 100°C for 30 minutes.
The mixture was cooled and neutralized by adding 20 g of 28% aqueous ammonia to obtain an aqueous solution of copolymer (1). According to GPC analysis, the obtained copolymer (1) has a number average molecular weight of 22,000, unreacted acrylic acid monomer (including ammonium acrylate) is 0.3 mol% (based on the amount charged), and unreacted IEO-5 is
It was 2.8 mol% (based on the amount charged). Reference example 2 3-methyl-3 was added to the reaction vessel used in reference example 1.
-10 ethylene oxide to buten-1-ol
Molar addition of unsaturated alcohol (hereinafter referred to as IEO−10
It is called. ) 492 g (0.935 mol as IEO-10) and 164 g of ion-exchanged water were charged. 95 after nitrogen replacement
The temperature was raised to .degree. C., and a solution of 91.6 g of maleic anhydride (0.935 mol as maleic anhydride) and 9.34 g of ammonium persulfate dissolved in 177 g of ion-exchanged water was added dropwise over 120 minutes. After dropping the solution, add 67 g of 7% ammonium persulfate aqueous solution at the same temperature.
The solution was added dropwise within minutes to complete polymerization. Next, 400 g of the polymerization reaction product obtained by cooling was collected, 400 g of ion-exchanged water was added, and the mixture was neutralized with 60 g of a 48% sodium hydroxide aqueous solution while stirring to form an aqueous solution of copolymer (2). Obtained. Copolymer obtained from GPC analysis
(2) had a number average molecular weight of 4300, and no unreacted monomer could be detected. Reference Example 3 Add ion-exchanged water to the reaction vessel used in Reference Example 1.
After charging 218g and raising the temperature to 100℃, add 447g of 37% sodium methacrylate aqueous solution (1.531 mol as sodium methacrylate) and 10%α while stirring.
- 155 g of sodium crotonate aqueous solution (0.144 mol as α-sodium crotonate), an unsaturated alcohol prepared by adding 5 mol of propylene oxide to 3-methyl-2-buten-1-ol (hereinafter referred to as
It is called PPO-5. ) 38.4g of 50% aqueous solution (PPO−
0.051 mol) and 142 g of a 3% ammonium persulfate aqueous solution were each added dropwise from separate dropping nozzles over 120 minutes. After the dropwise addition was completed, the copolymerization reaction was continued for another 30 minutes at the same temperature, and then cooled to obtain an aqueous solution of copolymer (3). From GPC analysis, the obtained copolymer (3) had a number average molecular weight of 4000, unreacted sodium methacrylate was 0.2% (based on the amount charged), and unreacted sodium α-crotonate was 0.4% (based on the amount charged). However, no unreacted PPO-5 was detected. Reference example 4 3-methyl-3 was added to the reaction vessel used in reference example 1.
-propylene oxide to buten-1-ol
665 g (0.221 mol as IPOEO-2040) of an unsaturated alcohol with 20 mol and then 40 mol of ethylene oxide added (hereinafter referred to as IPOEO-2040),
Fumaric acid 12.8g (0.110 mol as fumaric acid)
and 214 g of ion-exchanged water were charged. After nitrogen replacement
The temperature was raised to 100°C, and 63.8 g of a 34% maleic anhydride aqueous solution (0.221 mol as maleic anhydride) and 27.6 g of a 10% ammonium persulfate aqueous solution were added dropwise thereto over 120 minutes. After the dropwise addition was completed, 16.5 g of a 10% ammonium persulfate aqueous solution was added dropwise over 60 minutes at the same temperature to complete the polymerization. Next, 400 g of the polymerization reaction product obtained by cooling was taken out, 400 g of ion-exchanged water was added, and the mixture was neutralized with 20 g of a 48% sodium hydroxide aqueous solution while stirring to form an aqueous solution of copolymer (4). Obtained.
From GPC analysis, the obtained copolymer (4) had a number average molecular weight of 6800, and unreacted fumaric acid was detected at 3 mol% (based on the amount charged), but unreacted maleic acid and unreacted
IPOEO-2040 was not detected at all. Reference example 5 2-methyl-3 was added to the reaction vessel used in reference example 1.
-30 ethylene oxide to buten-2-ol
593 g (0.350 mol as BEOPO-305) of unsaturated alcohol with 5 mol of propylene oxide added (hereinafter referred to as BEOPO-305), 22.8 g of itaconic acid (0.175 mol as itaconic acid)
and 214 g of ion-exchanged water were charged. After nitrogen replacement
The temperature was raised to 100°C, and 100.7 g of a 34% maleic anhydride aqueous solution (0.350 mol as maleic anhydride) and 43.6 g of a 10% ammonium persulfate aqueous solution were added dropwise thereto over 120 minutes. After the dropwise addition was completed, 26.2 g of a 10% ammonium persulfate aqueous solution was added dropwise over 60 minutes at the same temperature to complete the polymerization. Next, 400 g of the reaction product obtained by cooling was collected, 400 g of ion-exchanged water was added, and the mixture was neutralized with 33 g of 48% sodium hydroxide aqueous solution while stirring to obtain an aqueous solution of copolymer (5). Ta. According to GPC analysis, the obtained copolymer (5) has a number average molecular weight of 6400.
So, unreacted maleic acid is 1.5 mol% (based on the amount charged),
Although 2 mol % (based on the amount charged) of unreacted itaconic acid was detected, no unreacted BEOPO-305 was detected. Comparative Reference Example 1 Instead of 191 g of 50% IEO-5 aqueous solution used in Reference Example 1, 26.8 g of 3-methyl-3-buten-1-ol was used.
Comparative copolymer (1) having a number average molecular weight of 3900 was obtained in exactly the same manner as in Reference Example 1, except that 164 g and 164 g of water were used. The amount of unreacted acrylic acid monomer was 0.7% (based on the amount charged), and the amount of unreacted 3-methyl-3-buten-1-ol was 3.5 mol% (based on the amount charged). Comparative Reference Example 2 In place of 492 g of IEO-10 used in Reference Example 2, 466 g of unsaturated alcohol (hereinafter referred to as AEO-10), which is obtained by adding 10 moles of ethylene oxide to allyl alcohol, was used for initial ion exchange. water
A comparative copolymer (2) having a number average molecular weight of 2,700 was obtained in exactly the same manner as in Reference Example 2, except that 190 g of ion-exchanged water was used instead of 164 g. Unreacted maleic acid is 7.3 mol% (based on the amount charged), unreacted AEO-10 is 8.4 mol%
(vs. amount of preparation). Comparative Reference Example 3 Instead of 492 g of IEO-10 used in Reference Example 2, an unsaturated alcohol (hereinafter referred to as
It is called GEO-10. ), and a comparative copolymer (3) having a number average molecular weight of 2200 was obtained in exactly the same manner as in Reference Example 2, except that 121 g of ion-exchanged water was used instead of 164g of ion-exchanged water initially charged. Unreacted maleic acid is 10 mol% (based on the amount charged), unreacted GEO-10 is
It was 12 mol% (based on the amount charged). Comparison reference example 4 In reference example 1, 451g of ion-exchanged water was initially charged to 460g.
g, and an unsaturated alcohol (hereinafter referred to as AAEO-5) obtained by adding 5 moles of ethylene oxide to acrylic acid instead of 191 g of 50% IEO-5 aqueous solution.
A comparative copolymer (4) having a number average molecular weight of 5,400 was obtained in exactly the same manner as in Reference Example 1 except that 182 g of a 50% aqueous solution was used. Unreacted acrylic acid monomer is 0.4 mol%
(based on the amount charged), and unreacted AAEO-5 was 3.2 mol% (based on the amount charged). Comparative Reference Example 5 Instead of 665 g of IPOEO-2040 used in Reference Example 4, an unsaturated alcohol obtained by adding 20 moles of propylene oxide and 40 moles of ethylene oxide to methacrylic acid (hereinafter referred to as MPOEO-2040) 665
A polymerization reaction was carried out in exactly the same manner as in Reference Example 4 except that g was used. However, unreacted maleic acid is 85 mol% (based on the amount charged), unreacted fumaric acid is 93 mol% (based on the amount charged),
Unreacted MPOEO-2040 was 33 mol % (based on the amount charged) and had extremely poor copolymerizability. Example 1 Place the following (note) in a glass Erlenmeyer flask with a capacity of 300 ml.
135 g of the liquid to be treated and 15 g of a 0.015% aqueous solution of copolymer (1) obtained in Reference Example 1 as a scale inhibitor.
After adding a reflux condenser, the temperature was pre-heated to 110±2℃.
Heat treatment was performed for 3.5 hours in an oil bath adjusted to
After cooling, scale is removed by passing through a 0.45 μ membrane filter, and the Ca hardness of the liquid is determined by JIS.
It was measured by the method described in K0101, and the calcium carbonate scale inhibition rate was calculated by the following formula. The results are shown in Table 1. (Note) Liquid to be treated Add water to 1.11g of calcium carbonate and make up the entire amount.
Aqueous solution dissolved by blowing carbon dioxide into 5000g Calcium carbonate scale suppression rate = C-B/A-B x 10
0 A: Ca hardness before heat treatment (=200ppm) B: Ca hardness in the liquid after the scale inhibitor-free test
Ca hardness (=24ppm) C: Ca in liquid after scale inhibitor addition test
Hardness (ppm) Examples 2 to 5 Examples except that copolymers (2) to (5) obtained in Reference Examples 2 to 5 were used instead of copolymer (1) as a scale inhibitor. The scale inhibition rate was calculated in exactly the same manner as in Example 1. The results are shown in Table 1. Comparative Examples 1 to 4 Completely the same as Example 1 except that the comparative copolymers (1) to (4) obtained in Comparative Reference Examples 1 to 4 were used instead of copolymer (1) as a scale inhibitor. Similarly,
The scale inhibition rate was calculated. The results are shown in Table 1. Comparative Example 5 Commercially available sodium polyacrylate (average molecular weight 4000) was used instead of copolymer (1) as a scale inhibitor.
The scale inhibition rate was calculated in exactly the same manner as in Example 1, except that . The results are shown in Table 1. Comparative Example 6 Commercially available sodium polymaleate (average molecular weight 1000) was used instead of copolymer (1) as a scale inhibitor.
The scale inhibition rate was calculated in exactly the same manner as in Example 1, except that . The results are shown in Table 1.

[Table] Example 6 Put 155 g of ion-exchanged water and 5 g of a 0.02% aqueous solution of copolymer (1) obtained in Reference Example 1 as a scale inhibitor into a glass bottle with a capacity of 225 ml, and
0.168% sodium bicarbonate aqueous solution 10g, 0.0192
% zinc chloride aqueous solution and 10 g of 0.29% calcium chloride dihydrate aqueous solution were added, and after adjusting the pH to 9 with sodium hydroxide, ion exchange water was added to make the total amount 200 g. After sealing the resulting supersaturated aqueous solution, place it in a water bath pre-adjusted to 70°C.
Soaked for 28 hours. After cooling, the solution was filtered through a 0.1μ membrane filter to remove scale, and the zinc concentration in the solution was measured according to the method described in JIS K0101, and the zinc scale inhibition rate was calculated using the following formula.
The results are shown in Table 2. Zinc scale suppression rate = Z-Y/X-Y x 100 Zinc concentration in the liquid after agent addition test (ppm) Examples 7 to 10 Copolymers (2) to (5) obtained in Reference Examples 2 to 5 were used instead of copolymer (1) as scale inhibitors. The scale inhibition rate was calculated in exactly the same manner as in Example 6 except that each of the following was used. The results are shown in Table 2. Comparative Examples 7-10 Same as Example 6 except that each of the comparative copolymers (1) to (4) obtained in Comparative Reference Examples 1 to 4 was used instead of copolymer (1) as a scale inhibitor. The scale inhibition rate was calculated in exactly the same manner. The results are shown in Table 2. Comparative Example 11 Commercially available sodium polyacrylate (average molecular weight 4000) was used instead of copolymer (1) as a scale inhibitor.
The scale inhibition rate was calculated in the same manner as in Example 6, except that . The results are shown in Table 2. Comparative Example 12 Commercially available sodium polymaleate (average molecular weight 1000) was used instead of copolymer (1) as a scale inhibitor.
The scale inhibition rate was calculated in the same manner as in Example 6 except that . The results are shown in Table 2.

【table】

Claims (1)

[Claims] 1. General formula (However, in the formula, A ¹ and A ² are each independently hydrogen,
represents a methyl group or -COOX ² , and A ¹ and A ² cannot be -COOX ² at the same time, A ³ represents hydrogen, a methyl group, or -CH ₂ COOX ³ , and A ³ is -CH ₂ COOX ³ . In this case, A ¹ and A ² each independently represent 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. represents. ) One or more unsaturated carboxylic acid monomers () represented by the general formula (However, in the formula, R ¹ and R ² each independently represent hydrogen or a methyl group, and R ¹ and R ² cannot be a methyl group at the same time, and R ³ is -CH ₂ -, -(CH ₂ ) ₂ -or-C( _CH3 ) _2-
and the total number of carbon atoms in R ¹ , R ² and R ³ is 3
, Y represents an alkylene group having 2 to 3 carbon atoms, and n
is an integer from 1 to 100. ) 40 to 99.5 mol% of unsaturated alcohol monomer () and 0.5 mol% of unsaturated alcohol monomer () ~
60 mol% (however, the total of () and () is 100
It is mole%. ) A scale inhibitor whose main component is a copolymer (A) derived by using the following ratio.