JPS5922698A - Scale preventive agent for boiler water and cooling water - Google Patents

Abstract

PURPOSE:To obtain an excellent scale preventive agent, by incorporating a wate soluble copolymer consisting of mono(meth)allylether of trivalent or higher polyhydric alcohol, unsatd. carboxlyic acid and other unsatd. monomers into said agent. CONSTITUTION:A water soluble copolymer (A) is produced by copolymerizing mono(meth)allylether of trivalent or higher polyhydric alcohol (a), unsatd. carboxylic acid (b) and, if necessary, other unsatd. monomers (c) are copolymerized in an aq. soln. The mol.wt. of the water soluble copolymer (A) is usually 400- 100,000, more preferably 500-20,000 and the molar ratio of the unit (a) thereof to the unit (b) is preferably (a):(b)=(1:0.3)-(1:10) in order to provide a scale preventive effect. The above-described water soluble copolymer is added at 1-100ppm to an object aq. system in the case of using the same as a scale preventive agent.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a scale inhibitor for boiler water and cooling water.

Today, large amounts of water are used as boiler water and cooling water in various industries. However, in such water,
Generally contains magnesium, calcium, zinc, bicarbonate, carbonate, sulfuric acid, silicic acid, and phosphoric acid ions.
As a result of water evaporation and concentration in the boiler water system, cooling system, and water system, poorly soluble compounds precipitate on, for example, heat exchangers and heat transfer surfaces, and scale is formed.

The formation of such scale not only reduces cooling or thermal efficiency, but also causes corrosion on pipes and heat transfer surfaces, obstructs fluid flow, and requires equipment operation to clean and remove the scale that has formed. This can cause various problems, such as having to temporarily suspend operations.

Conventionally, various scale inhibitors have been proposed in order to prevent the formation of scale that causes such unexpected losses.

As such scale inhibitors, inorganic and organic acid compounds (polymerized phosphates, alkyl phosphates, alkyl phosphites, etc.), synthetic polymers (acrylic acid and maleic acid homo- and copolymers, etc.) are used. Can be mentioned. Among these, the scale inhibitor has rapidly become popular, but it has not always been possible to obtain completely satisfactory results in terms of scale prevention performance.

An object of the present invention is to provide a scale inhibitor that is superior to conventional scale inhibitors in terms of instantaneous scale prevention performance.

That is, the present invention is a mono(meth)allyl ether unit (a) of a polyhydric alcohol (in the unsaturated carboxylic acid (salt) unit) and, if necessary, other unsaturated monomer units (0). This is a scale inhibitor for seawater desalination, which is characterized by containing a water-soluble copolymer (A) having the following.

The mono(meth)allyl ether of a trivalent polyhydric alcohol forming the unit (a) of the copolymer (A) in the present invention is as follows.

General formula - River ■ CH2= 0-0H20(Yl) (OH),
(1) (wherein 111 is ■ or OH3, Y
, P is an integer of 2 or more, preferably an integer of 2 to 7, particularly preferably 2 to 8.
) is an integer of ).

The polyhydric alcohol residue of trivalent tab refers to a group obtained by removing a hydroxyl group from a polyhydric alcohol.

The polyhydric alcohol that forms the residue of the polyhydric alcohol in the third measurement is an aliphatic polyalcohol.

Examples include aliphatic amine polyhydric alcohols and/or their alkylene oxide adducts. Examples of aliphatic polyhydric alcohols include aliphatic tetrahydric alcohols such as aliphatic octahydric alcohol-I tohaglycerin, 1,2,4-butanetriol, trimethylolethane, trimethylolpropane, and 1,2,6-hexandriol. For example, Pentaerythritol.

erythritol, d- and l-traisotho, etc.

Aliphatic pentahydric alcohols such as d- and l-aravit, adonisotho, etc., aliphatic hexahydric alcohols such as d
- and l-sorbitol, d- and l-mannite and sugars such as d-glucose, d-galactose, d-xylose, saccharose, lactose, maltose and aliphatic aminopolyhydric alcohols such as l - Reethanolamine, etc., and mixtures of two or more thereof. Furthermore, examples of alkylene oxide adducts include ethylene oxide and/or propylene oxide adducts. The number of moles of alkylene oxide added is usually 1 to 40
Preferably it is 1-10. The number of moles added per 0.0 cm is usually 1 to 5. Preferably it is 1-3. Among polyhydric alcohols.

Trihydric alcohols are preferred, particularly glyceric acid and trimethylolpropane.

For example, the mono(meth)allyl ether of a polyhydric alcohol with a measuring tool has the following general formula am,, = 6-c■2o(Ao)n(ca materialn云C■2)m20(AO)n2■1 06AO)nl ・・・・・・(2)CH20(AO
)n2■ ・・・・・・(5) [The use in the formula is the same as in general formula (1); R2 is OH3 or C2H) A is an alkylene group having 2 to 3 carbon atoms i''+n
l+n2. n3 is 0 whose sum is 0 or 1 to 5
Or a positive integer i? nt, 'fn2 is an integer from 1 to 4].

General formulas (2), (3), (4), (5
) in nl, n2. Those in which n3 is 0 are preferred from the viewpoint of the method for producing the compound.

A specific compound is 1-(meth)allyloxy-2
, 8-dihydroxypropane 12-(meth)allyloxy-1,3-dihydroxypropane; 1-(meth)aryloxy-3,4-dihydroxyphthane 11-(meth)allyloxy-2,2-dihydroxymethylbutane;
i (meth)allyloxy-2,2-dihydroxymethylbutane; 1 (meth)allyloxyethoxy-2,
Examples include 3-dihydroxypropane and 1-(meth)allyloxy-2,2,2-)limethylolethane. Among these, preferred are 1-(meth)allyloxy-2,3-dihydroxypropane i2 (meth)allyloxy-1,3-dihydroxypropane and 1-(meth)allyloxy-2,2-dihydroxymethylbutane.

Monomers constituting the unsaturated carboxylic acid (salt) unit include monoethylenically unsaturated polycarboxylic acids (salts) [maleic acid (m), fumaric acid (m), itaconic acid (salt), etc.], monoethylene unsaturated monocarboxylic acids (salts) [(meth)acrylic acid (salts), crotonoic acid (salts), cinnamic acid (
salt), vinylbenzoic acid (salt), etc. Preferred among these are acrylic acid (salts) and especially maleic acid (salts), and mixtures of these two.

The unsaturated carboxylic acid (salt) unit (b) may be in the acid form or may be an alkali metal, ammonium or amine salt. The alkali metal is Na.

Examples include K and Li. As an amine, carbon number is 1
Mono-, di-, and trialkylamines having ~5 alkyl groups; mono-, di-, and trialkanolamines such as triethanolamine; heterocyclic amines such as pyridine; and the like.

Among the unsaturated carboxylic acids (salts), other unsaturated monomers (C), which may be used as necessary, can be arbitrarily selected as long as the copolymer (copolymer) maintains water solubility. Examples of this unsaturated monomer include the following.

(1) Hydrophilic unsaturated monomers 1) Monoethylenically unsaturated sulfonic acid monomers: aliphatic or aromatic monoethylenically unsaturated sulfonic acids such as vinyl sulfonic acid, styrene sulfonic acid; (meth)allylsulfone [(meth)allylsulfonic acid, 2-hydroxy-3-(meth)allyloxypropanesulfonic acid, etc.]; (meth)acrylsulfonic acids [sulfopropyl(
meth)acrylate, 2-hydroxy-8-(meth)acryloxypropylsulfonic acid, 2-(meth)acryloylamino-2,2-dimethylethanesulfonic acid, etc.]
alkali metal salts, ammonium salts of sulfonic acids;
Amine salts etc. 2) Monoethylenically unsaturated alcohols: (meth)allyl alcohol etc. 8) Monoethylenically unsaturated mono- or polycarboxylic acid polyols (alkylene glycols).

Glycerin, polyoxyalkylene glycol, etc.) Esters: Hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, triethylene glycol (meth)acrylate, etc. (2) Weakly hydrophilic to hydrophobic monomers 1) Monoethylenic Alkyl esters of unsaturated carboxylic acids: methyl (meth)acrylate, ethyl (meth)acrylate, maleic acid diethyl ester, 2-ethylhexyl (meth)acrylate, dotecyl (meth)acrylate, stearyl (meth)acrylate, etc. 2) Monoethylenic Unsaturated amides: (meth)acrylamide; N-alkyl (meth)acrylamide such as N-methylallylajt'; Esters of alcohols: vinyl acetate, vinyl propionate, (meth)allyl acetate, etc. 4) Monoethylenically unsaturated nitriles: (meth)acrylonitrile, etc. 5) Aromatic monoethylenically unsaturated monomers: styrene, (
L-alkylstyrene such as monomethylstyrene 6) Monoethylenically unsaturated ether monomers: vinyl ethyl ether, vinyl propyl ether, vinyl isobutyl ether, allyl ethyl ether, etc. (3) Halogen-containing monomers: vinyl chloride, Preferred among these other unsaturated monomers, such as vinylidene chloride, are vinylsulfonate, styrenesulfonic acid, and the like.

(meth)allyl alcohol, (meth)acrylamide,
Vinyl acetate, styrene, vinyl chloride, and mixtures of two or more of these.

Considering the scale prevention effect, the molar ratio of units (a) and units (b) in the water-soluble copolymer (i) in the present invention is as follows: a (a) two (b) = t: 0. 8-1:
It is 10.

In the molar ratio shown, when (b) is 03%, (a) remains in the system and it is difficult to completely copolymerize (b).
) exceeds 10, the effect of the hydroxyl groups in the resulting water-soluble copolymer () decreases, and a sufficient scale prevention effect cannot be obtained. When (b) is an unsaturated monocarboxylic acid (salt), preferably (a): (b)-1: 0.8 to 1. :8
``'Qh When (b) is an unsaturated polycarboxylic acid (salt), the equivalent amount of carboxyl groups per mole is more than twice that of an unsaturated monocarboxylic acid (salt), so (a) is preferable. :(b)-1:0.4 to 1:4.Also, the total of (a) and (b) in (A) is usually preferably 50% or more based on the weight of (A). is 65% or more.The sum of (a) and (b) is 50%.
When using rice, the effect of the hydroxyl groups in the resulting water-soluble copolymer (A) decreases, and a sufficient scale prevention effect cannot be obtained. The amount of unit (e) is not particularly limited as long as the copolymer shows water solubility, but it is usually 50% or less, preferably 8% or less [(C) is a weakly hydrophilic to hydrophobic monomer unit, the amount is usually 80% or less, preferably 20% or less. If the amount of (e) is greater than L, the effect of the resulting water-soluble copolymer GA) will be reduced and a sufficient scale prevention effect will not be obtained.

The water-soluble copolymer (A) in the present invention is prepared by copolymerizing three mono(meth)allyl ethers of polyhydric alcohols, an unsaturated carboxylic acid, and other unsaturated monomers as necessary in an aqueous solution. It can be manufactured by A specific method for producing such a copolymer is described in Japanese Patent Application No. 57-4.
Examples include the method described in No. 368 (in the case of maleic acid) and the method in which other unsaturated carboxylic acids are used in place of maleic acid.

In addition, the water-soluble copolymer (A) is produced by copolymerizing their precursors [monomers that can become (a) or (b) by hydrolysis], and then adding water to the monomers. It can also be produced by decomposition. For example, instead of an unsaturated carboxylic acid, its anhydride (maleic anhydride,
(such as itaconic anhydride), esters (such as the alkyl esters of monoethylenically unsaturated levonic acids listed above), nitriles (such as acrylonitrile), amides (such as acrylamide), etc., and/or 8 g of polyhydric alcohols. Copolymerization is carried out using its acetal, ester, etc. instead of mono(meth)allyl ether, and then hydrolyzed to form monomer units (a), (b) and, if necessary, (
0) can be produced.

As the acetal and ester of mono(meth)allyl ether of polyhydric alcohol in the method described above, for example, those represented by the following general formulas (5), (6) and (7) can be used.

扛.

CH2= 0-0H20iY270X, )p 2
(6) or a group excluding all 几 is ■ or CH,
, 几l is H, CH3 or 02H, Xl is ■ or a residue of a monocarboxylic acid (acetic acid, etc.), X2 is a residue of a dicarboxylic acid (oxalic acid, maleic acid, etc.) or >C=O.

P2 is an integer greater than or equal to 1. In the method described above, polymerization can be carried out by a conventional method (such as radical polymerization or solution polymerization), and hydrolysis can also be carried out by a conventional method (under heating or in the presence of an acid or alkali).

The molecular weight of the water-soluble copolymer (A) in the present invention is usually 4.
00-100,000, preferably 500-20,0
It is 00. The molecular weight can be measured using an aqueous G, P, C, (gel permeation chromatograph) or vapor pressure permeability meter.

The scale inhibitor of the present invention contains the copolymer described in t as an active ingredient, and is a pl-
The I range is also not particularly limited.

Preferably it is 7-12.

As mentioned above, the target water systems for this scale inhibitor include boiler water systems and cooling water systems. Especially calcium phosphate and zinc phosphate in these water systems.

Although zinc hydroxide scales frequently occur, the scale inhibitor of the present invention exhibits a remarkable effect in preventing the formation of these scales.

can do. Known scale inhibitors include polyacrylates, partial hydrolysates of polyacrylamide,
Maleic acid homo and copolymers.

Metal corrosion inhibitors include oxycarboxylic acids, thiazoles, triazoles, penozotriazoles, and amines, such as itaconic acid homo and copolymers, acrylic acid copolymers containing 2-hydroxyethyl methacrylic acid, etc. , imines, hydroxamic acids, polyvalent metal salts (zinc, nickel, etc.), etc. may be combined with phosphate scale inhibitors and anticorrosive agents such as phosphates and phosphonates, depending on the circumstances and necessity. . In this case, the amount of phosphorus itself added can be reduced by blending with these phosphoric acid scale inhibitors. Furthermore, by blending the scale inhibitor of the present invention with the phosphorus-containing corrosion inhibitor alone, a synergistic effect can be obtained, and the amount of the phosphoric acid-based corrosion inhibitor added can be reduced.

This invention will be further explained below with reference to Examples and Reference Examples, but the invention is not limited thereto.

Reference example 1 11 four-roof flask, stirrer, thermometer, 1 dropping funnel,
Attach the nitrogen gas introduction pipe and reflux cooling pipe, and
-allyloxy-2,3-dihydroxypropane 182
116 g of maleic acid and 400 g of arsenic water were charged. Separately, 18 grams of ammonium persulfate was placed in a beaker, 90 grams of water was added thereto, and the aqueous initiator was placed in a dropping funnel. After removing oxygen from the system with nitrogen gas, the monomer aqueous solution in the flask was heated to 85°C, and the initiator aqueous solution was added dropwise from a two-dropping funnel over 30 minutes. Subsequently, the mixture was aged at 90°C for 1 hour to obtain a transparent and uniform aqueous solution of water-soluble copolymer 748FI. The solids content of the aqueous solution is 8
4.896 (W/W), and the molecular weight was 1000 by GPC.

The aqueous solution was used as the scale inhibitor in Case I of Example 1.

Reference Example 2 850y of toluene was placed in a reaction vessel similar to Reference Example-1 and heated to 80°C. Separately in a beaker, 2-methyl-4-
72f of allyloxymethyl-1,3-dioxolane and 98f of maleic anhydride were taken and heated to 50°C to dissolve them. After cooling to room temperature, benzoyl peroxide 1
8 g was added and uniformly dissolved to create a monomer solution.

This monomer solution was added dropwise to the previously prepared toluene over 30 minutes,
Polymerization was continued at 80°C for 1 hour and then at 100°C for 1 hour. After the polymerization was completed, it was cooled to 40°C, the precipitated copolymer and the toluene solution were separated, and dried under reduced pressure.
114 g of copolymer was obtained.

800 g of water was added to the L copolymer and boiled, and acetaldehyde produced by hydrolysis was distilled out of the system together with water in 1 hour. After further heating for 2 hours and hydrolysis, 345 g of a transparent and uniform aqueous solution of the water-soluble copolymer was obtained. The solid content of the aqueous solution was 51% (W/W), and the molecular weight was 600 as determined by GPC.

The aqueous solution was used as a case river scale inhibitor in Example-1.

Reference Example 3 An aqueous solution was prepared in the same manner as in Reference Example 1 except for changing the raw materials or ratios. Cases Ill, IV and V of Example-1 were prepared.
It was used as a scale inhibitor.

Reference Example 4 300g of toluene was heated at 50° in the same reaction vessel as Reference Example 1.
The mixture was heated and dissolved in C, and styrene 6,'f was mixed therein.

After cooling to room temperature, add benzoyl peroxide 711,
A monomer solution was prepared by uniformly dissolving the mixture.

This monomer solution was added dropwise to the previously prepared toluene over 45 minutes.

Polymerization was continued at 80°C for 1 hour and at 100°C for 2 hours. After the polymerization was completed, the copolymer was cooled to 40'C, the precipitated copolymer was separated from P, and then dried under reduced pressure to obtain a copolymer of 116f. Add 5511 water to the copolymer and reflux.

Hydrolysis was carried out by heating for 8 hours, and the resulting homogeneous aqueous solution was evaporated to dryness to obtain hydrolyzed copolymer 981. The hydrolysis rate was 93% based on the saponification value, and the molecular weight was 1100 based on GPC.

98 g of water was added to the copolymer to give a solid content of 500% (
W/W) was prepared as an aqueous solution and used as a scale inhibitor in Case ① of Example 1.

Example 1 Monoallyl ether unit (a) of the triol listed in Table 1 obtained in Reference Examples 1 to 4, unsaturated carboxylic acid (@ unit (b)
), and if necessary, an aqueous solution containing other unsaturated monomer units (0), was used as a scale inhibitor to conduct an inhibition test for calcium phosphate, supplementary hydroxide, and zinc phosphate scales. The test conditions for each scale are as follows.

a) Common procedure Various test solutions were kept in a constant temperature water bath at 60°C, and a predetermined amount of a scale inhibitor was added thereto, left to stand for 40 hours, and then filtered with a membrane filter for 3T.

Phosphoric acid and/or #≠ in water measures the residual amount of zinc ions.

b) Add calcium chloride to 100 ppm (100 ppm) of calcium phosphate scale inhibition test solution (100 ppm
) and sodium orthophosphate at 10 ppm (PO3
4-) were added and p■ was adjusted.

1) Zinc hydroxide scale suppression test solution Chlorination power 1 in pure water
Added 1100pp of 1/Sium (as CaC0), 1100pp of bicarbonate of soda (C straight blade, closed) and 5ppm of zinc chloride (as Zn),
■Adjusted.

Engineering) Zinc phosphate scale suppression test solution Add tooppm of calcium chloride to pure water (as Ca (30)), 1100 ppm of bicarbonate of soda (as 0aCO3), 8.5 ppm of zinc chloride (as Zn), and 6 ppm of sodium phosphate (as PO2) was added to adjust the p■, Reiken Kakeru Sorinmu was Doo, fA-
Shi・j・su.

Incidentally, as a comparative example, a scale inhibition test was conducted on a monovinyl alcohol I-enriched oleic acid copolymer and a vinyl alcohol-Σ4 acrylic acid copolymer under the same conditions as in Section t, and the results are also shown.

The scale precipitation suppression limit concentration is the minimum amount of scale inhibitor added ( This is an indicator defined as (solid content equivalent).

(c) From these results, the scale inhibitor c of the present invention has superior scale prevention performance for calcium phosphate-based, zinc hydroxide-based, and zinc phosphate-based scales compared to each copolymer shown as a comparative example. It can be seen that the

Patent applicant: Sanyo Chemical Industries, Ltd.

Claims (1)

[Scope of Claims] Mono(meth)allyl ether unit (a) of polyhydric alcohol with a valence of 1.3 or higher (t), unsaturated carboxylic acid (salt) unit jb)
and, if necessary, a water-soluble copolymer (A) having another unsaturated monomer unit (C). A scale inhibitor for boiler water and cooling water. 2. (a) and (h) (f) Mo11/proportion is (a
):(b)=1:0.8 to 1:10. 8. The inhibitor according to claim 1 or 2, wherein the sum of (a) and (b) is 50% or more based on the weight of (A). 4. The molecular weight of the water-soluble copolymer (A) is 0 to 400-10.
00, the inhibitor according to any one of claims 1 to 8. 5. The amount of water-soluble copolymer (A) added to water is 1 to i
The inhibitor according to any one of claims 1 to 4, which is o o ppm. 6.8 The inhibitor according to any one of claims 1 to 5, wherein the polyhydric alcohol of the measuring tool t is an aliphatic triol and/or an alkylene oxide adduct thereof. 7. Claim 6, wherein the aliphatic triol is a compound selected from the group consisting of glycerin, 1,2.4-butanetriol, 1,2.6-hexatriol, trimethylolethano, and trimethylolpropane. Inhibitors listed. 8. The inhibitor according to claim 6 or 7, wherein the alkylene oxide adduct is an ethylene oxide and/or propylene oxide adduct. 9. The inhibitor according to any one of claims 1 to 8, wherein the unsaturated carboxylic acid is maleic acid.