JPH11171939A - Water-soluble graft polymer, scale-preventing agent and prevention of scale using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an easily producible scale-preventing agent effective in suppressing a scale of esp. potassium phosphate or zinc hydroxide, and to provide a method for preventing the scale by using the agent. SOLUTION: This agent comprises a polymer obtained by subjecting (A) a polyether compound having a number-average molecular weight of <200 and (B) a monoethylenic unsaturated monomer component to graft polymerization in the absence of any solvent and another polymer obtained by subjecting the compound A and the component B to graft polymerization, wherein a hydroxyl value of each polymer is >=200 mgKOH/g and an acid value thereof is >=100 mgKOH/g.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-soluble graft polymer, a scale inhibitor and a method for preventing scale using the same.

[0002]

2. Description of the Related Art In a cooling water system, a boiler water system, a seawater desalination apparatus, a pulp dissolving pot, a black liquor concentrating pot, an oil field, and the like, calcium carbonate, calcium phosphate,
Precipitates (scales) such as zinc hydroxide and magnesium silicate adhere, which may cause various operational problems such as a decrease in thermal efficiency and local corrosion.

In particular, when an iron pipe is used in an aqueous system, it is necessary to use a large amount of a phosphoric acid compound, a zinc salt or the like as a corrosion inhibitor. In this case, a scale made of calcium phosphate or zinc hydroxide is required. Is a problem.

[0004]

SUMMARY OF THE INVENTION USP 4,659,481
The specification describes that a polymer composed of a monomer component having a hydroxyl group and a monomer component having a sulfonic acid group is effective in suppressing the scale of calcium phosphate, zinc hydroxide and the like. However, although such a polymer has a certain effect in suppressing the scale, there is a problem that the synthesis is difficult because a monomer component having a special structure is used.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a scale inhibitor which is particularly effective in controlling the scale of calcium phosphate and zinc hydroxide and is easy to produce, and a method of preventing scale using the same.

[0006]

As a result of extensive studies by the present inventors, it has been found that a polymer obtained by graft-polymerizing a monoethylenically unsaturated monomer component to a polyether compound having ethylene oxide as a constitutional unit can be easily produced. Focusing on that, the number average molecular weight of the polyether compound as a raw material of such a polymer,
The present inventors have found that the above problems can be solved by specifying the hydroxyl value and the acid value, and have reached the present invention.

Further, a water-soluble graft polymer having a specified number average molecular weight of the raw material polyether compound has an excellent weight without turbidity and no phase separation when converted to an aqueous alkali salt solution by specifying a grafting method. They have found that they can be united, and have reached the present invention. That is, the water-soluble graft polymers according to the present invention is represented by the following formula: a repeating unit represented by -CH ₂ -CH ₂ -O-, polyethers having average molecular weight of less than 200 having at least one or more in one molecule A water-soluble graft polymer obtained by graft-polymerizing a monoethylenically unsaturated monomer component (B) containing an unsaturated carboxylic acid-based monomer as an essential component to a compound (A) without using a solvent. .

[0008] In the above, the hydroxyl value is 30 mg KOH
/ G or more, and the acid value is preferably 50 mgKOH / g or more. The scale inhibitor according to the present invention is a polyether compound having at least one repeating unit represented by the following general formula: —CH ₂ —CH ₂ —O— in one molecule and having a number average molecular weight of less than 200 ( A) a scale inhibitor containing a polymer obtained by graft polymerization of a monoethylenically unsaturated monomer component (B) containing an unsaturated carboxylic acid monomer as an essential component,
The polymer has a hydroxyl value of 200 mgKOH / g or more and an acid value of 100 mgKOH / g or more.

In the above, the polyether compound (A)
Is preferably any of polyalkylene glycol, alkoxypolyalkylene glycol, and aryloxypolyalkylene glycol. Further, as at least a part of the monoethylenically unsaturated monomer component (B),
It is preferable to use a sulfonic acid group-containing monomer and / or a hydroxyl group-containing monomer.

The above-described scale inhibitor is effective as a scale inhibitor for calcium phosphate or zinc hydroxide. The above-mentioned scale inhibitor, a phosphoric acid compound and / or
Or, a method of preventing scale in which zinc salt and a total of 0.5 to 50 ppm are added to an aqueous system greatly improves not only the effect of preventing scale of the pipe but also the effect of preventing corrosion.
Very useful.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The scale inhibitor according to the present invention will be described. The scale inhibitor according to the present invention includes a polymer obtained by graft-polymerizing a monoethylenically unsaturated monomer component (B) to a polyether compound (A) having a number average molecular weight of less than 200, and has a hydroxyl value of such a polymer. 200mg
KOH / g or more and an acid value of 100 mgKOH / g or more. The hydroxyl value of the polymer is 200 mgK
When the content is OH / g or more, the ability of calcium phosphate and zinc hydroxide to prevent scale is greatly improved. By setting the acid value of the polymer to 100 mgKOH / g or more, the ability of calcium carbonate to prevent scale is exhibited. The hydroxyl value is preferably 250 mgKOH / g or more,
More preferably, it is 0 mgKOH / g or more. The acid value is preferably 120 mg KOH / g or more,
More preferably, it is at least 40 mgKOH / g.

The polyether compound (A) used for the production of such a graft polymer has a general formula: —CH ₂ —CH ₂
It has a number average molecular weight of less than 200, having at least one repeating unit represented by -O- in one molecule,
A cyclic ether containing ethylene oxide as an essential component and further containing other alkylene oxides as necessary.
It is obtained by performing polymerization by a known method or the like in the presence of a compound to be reacted, which is a starting point of polymerization.

Other alkylene oxides used to obtain the polyether compound include, for example, propylene oxide, isobutylene oxide, 1-butene oxide, 2-butene oxide, trimethylethylene oxide, tetramethylethylene oxide, butadiene monoxide, styrene oxide 1,1-diphenylethylene oxide, epifluorohydrin, epichlorohydrin, epibromohydrin, glycidol, butyl glycidyl ether, hexyl glycidyl ether, allyl glycidyl ether, ethylene glycol diglycidyl ether, cyclohexene oxide, dihydronaphthalene oxide, Vinylcyclohexene monoxide, oxetane, tetrahydrofuran, 1,4-epoxycyclohexane, etc. Bets can be, they are used alone or in combination.

The compound to be reacted is a compound that serves as a starting point of polymerization of the cyclic ether, and there is no particular limitation on its type, molecular weight, and the like. Examples of the compound to be reacted include water; hydrogen; oxygen; carbon dioxide; alcohol; hydrogen halide; ammonia;
Carboxylic acids; acid halides; lactones; aldehydes;
Benzene and the like can be mentioned.
Used over seeds. Among them, at least one selected from water and alcohol is preferable as the compound to be reacted.

Examples of the alcohol include primary aliphatic alcohols having 1 to 22 carbon atoms, such as methanol, ethanol, n-propanol and n-butanol; phenol, iso-propylphenol, octylphenol, tert-butylphenol, nonylphenol and the like.
Aromatic alcohols such as naphthol; secondary alcohols having 3 to 18 carbon atoms such as iso-propyl alcohol and alcohols obtained by oxidizing n-paraffin; tertiary alcohols such as tert-butanol; ethylene glycol, diethylene glycol, propanediol And diols such as butanediol and propylene glycol; triols such as glycerin and trimethylolpropane; and polyols such as sorbitol. These may be used alone or in combination of two or more.

The type of polymerization of the cyclic ether is not particularly limited. Anionic polymerization using a strong alkali such as an alkali metal hydroxide or an alcoholate, an alkylamine or the like as a base catalyst, a halide of a metal or a metalloid, or the like. , Or a coordination polymerization using a combination of alkoxides of metals such as aluminum, iron and zinc, alkaline earth compounds, Lewis acids and the like.

Further, as the polyether compound (A), at least one terminal hydroxyl group of the polyether obtained by the above-mentioned polymerization is converted to a fatty acid having 2 to 22 carbon atoms such as acetic acid or acetic anhydride, an acid anhydride thereof, and a succinic acid. Examples thereof include those esterified with a dicarboxylic acid such as an acid, succinic anhydride, and adipic acid. In this case, hydrolysis is preferably performed after graft polymerization for the purpose of improving the hydroxyl value.

As these polyether compounds (A),
By using polyalkylene glycol, alkoxy polyalkylene glycol, or aryloxy polyalkylene glycol, a polymer having a large acid value and a hydroxyl value can be obtained. It is important that the number average molecular weight of the polyether compound (A) is less than 200;
It is preferably less than 0, more preferably less than 180. When the number average molecular weight is 200 or more, the ability of calcium phosphate and zinc hydroxide to prevent scale tends to decrease.

Monoethylenically unsaturated monomer component (B)
Contains an unsaturated carboxylic acid monomer as an essential component,
It may further include another unsaturated monomer copolymerizable with the unsaturated carboxylic acid monomer. The unsaturated carboxylic acid monomer is an ethylenically unsaturated carboxylic acid, and / or
An ester that produces a carboxylic acid by hydrolysis.

Examples of the ethylenically unsaturated carboxylic acid include (meth) acrylic acid; maleic acid; fumaric acid;
Maleic anhydride and the like can be mentioned, and one or more of these can be used. When the unsaturated carboxylic acid monomer is at least one selected from (meth) acrylic acid, maleic acid, fumaric acid and maleic anhydride,
The acid value and dispersibility of the obtained graft polymer are increased.

Further, it is preferable that 25% by weight or more of the monomer component (B) is (meth) acrylic acid.
When the amount of (meth) acrylic acid is small, the acid value of the obtained graft polymer is small, and various performances such as polyvalent metal ion chelating ability and dispersing ability are hardly satisfied. The ester that produces a carboxylic acid by hydrolysis is not particularly limited as long as it is an ester of the above-mentioned ethylenically unsaturated carboxylic acid. For example, maleic acid such as monomethyl maleate, dimethyl maleate, monoethyl maleate, diethyl maleate and the like can be used. Esters of fumaric acid such as monomethyl fumarate, dimethyl fumarate, monoethyl fumarate and diethyl fumarate; methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, (meth) acrylate ) Esters of (meth) acrylic acid such as stearyl acrylate, hydroxyethyl (meth) acrylate and hydroxypropyl (meth) acrylate; aminoalkyl (meth) acrylates such as dimethylaminoethyl (meth) acrylate; Sulfoethyl (meth)
Examples thereof include sulfoalkyl (meth) acrylates such as acrylate, and one or more of these are used. When only the above ester is used, a step of converting a part or all of the ester group to a carboxyl group after the graft polymerization is required. Therefore, it is preferable that the unsaturated carboxylic acid monomer essentially includes an ethylenically unsaturated carboxylic acid from the viewpoint that this conversion step becomes unnecessary.

The other unsaturated monomer copolymerizable with the unsaturated carboxylic acid monomer is not particularly limited as long as it is a monomer other than the unsaturated carboxylic acid monomer. Meta)
Amide group-containing monomers such as acrylamide; vinyl esters such as vinyl acetate, vinyl propionate, vinyl pivalate, vinyl benzoate, and vinyl cinnamate; alkenes such as ethylene and propylene; and styrene and styrene sulfonic acid. Aromatic vinyl monomers; trialkyloxysilyl group-containing vinyl monomers such as vinyltrimethoxysilane and vinyltriethoxysilane; silicon-containing vinyl monomers such as γ- (methacryloyloxypropyl) trimethoxysilane Monomers: maleimide, methylmaleimide, ethylmaleimide, propylmaleimide, butylmaleimide, octylmaleimide, dodecylmaleimide,
Maleimide derivatives such as stearylmaleimide, phenylmaleimide and cyclohexylmaleimide; vinyl monomers containing nitrile groups such as (meth) acrylonitrile;
Aldehyde group-containing vinyl monomers such as (meth) acrolein; 2-acrylamido-2-methylpropanesulfonic acid, methallylsulfonic acid, styrenesulfonic acid, allylsulfonic acid, vinylsulfonic acid, 2-hydroxy-
Sulfonic acid group-containing monomers such as 3-allyloxy-1-propanesulfonic acid and 2-hydroxy-3-butenesulfonic acid; alkyl vinyl ethers such as methyl vinyl ether and ethyl vinyl ether; vinyl chloride, vinylidene chloride, allyl chloride; Allyl alcohol: other functional group-containing monomers such as vinylpyrrolidone and the like can be mentioned, and one or more of these are used.

As at least a part of the monomer component (B), a sulfonic acid group-containing monomer, a hydroxyl group-containing monomer (including a monomer that produces a hydroxyl group by hydrolysis (for example, vinyl acetate)), It is preferable to use at least one selected from a sulfonic acid group-containing monomer and a hydroxyl group-containing polymer because the effect of suppressing scale, particularly the effect of suppressing calcium phosphate and zinc hydroxide, is enhanced.

The graft polymerization is preferably performed in the presence of a polymerization initiator. As the polymerization initiator, a known radical initiator can be used, and an organic peroxide is particularly preferable. Examples of the organic peroxide include methyl ethyl ketone peroxide, cyclohexanone peroxide, 3,3,5-trimethylcyclohexanone peroxide, methylcyclohexanone peroxide, methyl acetoacetate peroxide,
Ketone peroxides such as acetylacetone peroxide; tert-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, 2,5-dimethylhexane-
2,5-dihydroperoxide, 1,1,3,3-
Tetramethylbutyl hydroperoxide, 2- (4
Hydroperoxides such as -methylcyclohexyl) -propane hydroperoxide; di-tert-
Butyl peroxide, tert-butylcumyl peroxide, dicumyl peroxide, α, α′-bis (tert-butylperoxy) p-diisopropylbenzene, α, α′-bis (tert-butylperoxy) p-isopropyl Hexin, 2,5-dimethyl-
2,5-di (tert-butylperoxy) hexane,
Dialkyl peroxides such as 2,5-dimethyl-2,5-di (tert-butylperoxy) hexyne-3; tert-butylperoxyacetate, tert
-Butylperoxylaurate, tert-butylperoxybenzoate, di-tert-butylperoxyisophthalate, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, tert-butylperoxyisopropylcarbonate, tert-butyl peroxyisobutyrate, tert-butyl peroxybivalate, tert-butyl peroxy neodecanoate, cumyl peroxy neodecanoate, tert-butyl peroxy-2-ethylhexanoate, tert
-Butylperoxy-3,5,5-trimethylcyclohexanoate, tert-butylperoxybenzoate, tert-butylperoxymaleic acid, cumylperoxyoctoate, tert-hexylperoxybivalate, tert-hexylperoxy Peroxyesters such as neohexanoate and cumylperoxyneohexanoate; n-butyl-4,4-bis (te
rt-butylperoxy) valate, 2,2-bis (tert-butylperoxy) butane, 1,1-bis (tert-butylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis ( tert-butylperoxy) cyclohexane, 2,2-bis (tert
Peroxyketals such as -butylperoxy) octane; acetyl peroxide, isobutyryl peroxide, octanoyl peroxide, decanoyl peroxide, lauroyl peroxide, 3,3,5-trimethylcyclohexanoyl peroxide, succi Nick acid peroxide, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, m-
Diacyl peroxides such as toluyl peroxide; di-isopropylperoxydicarbonate, di-
2-ethylhexyl peroxydicarbonate, di-n
-Propylperoxydicarbonate, bis- (4-t
tert-butylcyclohexyl) peroxydicarbonate, dimyristyl peroxydicarbonate, di-methoxyisopropyl peroxydicarbonate, di (3
-Methyl-3-methoxybutyl) peroxydicarbonates such as peroxydicarbonate and di-allylperoxydicarbonate; and other organic peroxides such as acetylcyclohexylsulfonyl peroxide and tert-butylperoxyallylcarbonate. These may be used alone or in combination of two or more.

The amount of the organic peroxide to be used is not particularly limited, but is preferably 0.1 to 30% by weight, more preferably 0.5 to 30% by weight, based on the monoethylenically unsaturated monomer component (B).
-20% by weight. If it is less than 0.1% by weight, the graft ratio to the polyether compound tends to decrease.
On the other hand, if it exceeds 30% by weight, the organic peroxide is expensive, which is economically undesirable. The organic peroxide is preferably added simultaneously with the ethylenically unsaturated monomer simultaneously and separately without previously mixing with the polyether compound, but may be added to the polyether compound in advance, It may be added to the monoethylenically unsaturated monomer.

An organic peroxide decomposition catalyst or a reducing compound may be used together with the organic peroxide. Examples of organic peroxide decomposition catalysts include metal halides such as lithium chloride and lithium bromide; metal oxides such as titanium oxide and silicon dioxide; hydrochloric acid, hydrobromic acid, perchloric acid, sulfuric acid, nitric acid and the like. Carboxylic acids such as formic acid, acetic acid, propionic acid, lacnic acid, isoleic acid, and benzoic acid, esters and metal salts thereof; pyridine, indole,
Heterocyclic amines such as imidazole and carbazole and derivatives thereof and the like can be mentioned.
Used over seeds.

Examples of the reducing compound include organometallic compounds such as ferrocene; metals such as iron, copper, nickel, cobalt and manganese such as iron naphthenate, copper naphthenate, nickel naphthenate, cobalt naphthenate and manganese naphthenate; Inorganic compounds capable of generating ions; inorganic compounds such as boron trifluoride ether adduct, potassium permanganate, perchloric acid; sulfur dioxide, sulfite, sulfate, bisulfite, thiosulfate, sulfoxylate, benzene Sulfinic acid and its substituents, sulfur-containing compounds such as homologues of cyclic sulfinic acids such as paratoluenesulfinic acid; octyl mercaptan, dodecyl mercaptan, mercaptoethanol, α-mercaptopropionic acid, thioglycolic acid
Mercapto compounds such as thiopropionic acid, sodium sulfopropyl α-thiopropionate and sodium sulfoethyl ester α-thiopropionate; nitrogen-containing compounds such as hydrazine, β-hydroxyethylhydrazine, and hydroxylamine; formaldehyde, acetaldehyde, propionaldehyde And aldehydes such as n-butyraldehyde, isobutyraldehyde and isovalerian aldehyde; ascorbic acid; and one or more of these are used.

The graft polymerization may be carried out in the presence of an acidic substance together with the organic peroxide. The acidic substance has a function of improving the graft ratio of the monoethylenically unsaturated monomer to the polyether compound, increasing the purity and dispersibility of the obtained graft polymer, and improving the scale preventing ability. The acidic substance is not particularly limited as long as it is an acidic substance, but at least one selected from organic sulfonic acid compounds, inorganic acids, and phosphoric acid compounds is preferable.

Examples of the organic sulfonic acid compound include aliphatic sulfonic acids such as methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid and octanesulfonic acid;
Aromatic sulfonic acids such as benzenesulfonic acid, benzenedisulfonic acid, naphthalenesulfonic acid, and naphthalenedisulfonic acid; chlorobenzenesulfonic acid, 1-naphthylamine-4-sulfonic acid (naphthionic acid), dobiasic acid, peric acid, and gamma acid (γ-acid) ), Aromatic acids having a nuclear substituent such as jaeic acid (J acid), koch acid, metanilic acid, toluenesulfonic acid, dodecylbenzenesulfonic acid, etc., and one or more of these can be used. Is done.

Examples of the inorganic acid include hydrochloric acid, hydrofluoric acid, hydrobromic acid, hydroiodic acid, perchloric acid, chlorous acid, hypochlorous acid, periodic acid, sulfuric acid, fuming sulfuric acid, and sulfurous acid. , Nitric acid, fuming nitric acid, manganic acid, permanganic acid, chromic acid, dichromic acid, etc., and one or more of these are used. Examples of the phosphoric acid compound include phosphoric acid, phosphorous acid, hypophosphorous acid, polyphosphoric acid,
Metaphosphoric acid, pyrophosphoric acid, methyl phosphate, ethyl phosphate, propyl phosphate, butyl phosphate, octyl phosphate,
Dodecyl phosphate, stearyl phosphate, phenyl phosphate,
Dimethyl phosphate, diethyl phosphate, dipropyl phosphate,
Examples thereof include dibutyl phosphate, dioctyl phosphate, didodecyl phosphate, distearyl phosphate, diphenyl phosphate, and the like. One or more of these are used.

The amount of the acidic substance used is not particularly limited.
0.05 to 20 based on the polyether compound
%, More preferably 0.1 to 15% by weight.
If the amount of the acidic substance is less than 0.05% by weight, a large amount of unreacted polyether compound remains, and the graft ratio of the monoethylenically unsaturated monomer tends to decrease. On the other hand, when the use amount of the acidic substance exceeds 20% by weight, the effect corresponding to the added amount may not be exhibited. The acidic substance may be added to the polyether compound in advance, or may be added to the monoethylenically unsaturated monomer.

The graft polymerization is preferably performed substantially without a solvent. When water or an organic solvent such as alcohol or toluene is used, the grafting efficiency of the monomer component (B) to the polyether compound (A) decreases. When a solvent is used for the addition of the polymerization initiator or the monomer component (B), it is preferable to reduce the amount as much as possible. It is preferable to immediately evaporate it.

The temperature of the graft polymerization is preferably 100 ° C. or higher, more preferably 110 ° C. or higher and 160 ° C.
It is as follows. When the temperature is lower than 100 ° C., the grafting efficiency of the monomer component (B) to the polyether compound (A) decreases. At a temperature higher than 160 ° C., the polyether compound (A) and the obtained graft polymer may be thermally decomposed.

At the time of graft polymerization, it is preferable to initially or partially charge the polyether compound (A). Also, when graft polymerization is carried out on a polyether compound (A) using (meth) acrylic acid and at least one monomer selected from the group consisting of maleic acid, fumaric acid and maleic anhydride as monomer components. , Maleic acid, fumaric acid, and maleic anhydride, at least half of which were previously mixed with the polyether compound (A) and heated to 100 ° C or higher, and then the remaining monomer components and the polymerization initiator were separately added. It is preferable to carry out graft polymerization. According to this method, the rate of introduction of maleic acid, fumaric acid, and maleic anhydride into the graft polymer can be significantly improved, and the molecular weight of the graft polymer can be adjusted.

The graft polymer obtained as described above can be used directly as a scale inhibitor. If necessary, a phosphorus compound, an acrylic acid polymer (salt), a maleic acid polymer (salt), acrylic acid / 3-allyloxy-
1,2-propanediol copolymer, acrylic acid / 2-
Allyloxy-1,2-propanediol copolymer, acrylic acid / 2-hydroxy-3-allyloxy-1-propanesulfonic acid copolymer, acrylic acid / maleic acid copolymer, acrylic acid / allyl alcohol copolymer, Acrylic acid / hydroxy methacrylate copolymer, maleic acid /
Ethylene sulfonic acid copolymer, maleic acid / styrene copolymer, maleic acid / pentene copolymer, maleic acid /
Carboxyl group-containing low molecular weight polymers such as allyl alcohol copolymer, maleic acid / ethylene copolymer, maleic acid / butadiene copolymer, aspartic acid polymer, glyoxylic acid polymer; organic sulfonic acid; sodium tripolyphosphate; Inorganic polyphosphates such as sodium hexametaphosphate; phosphonic acids such as nitrilotrimethylenephosphonic acid, hydroxyethylidene diphosphonic acid, ethylenediaminetetramethylenephosphonic acid and phosphonobutanetricarboxylic acid; metal salts such as zinc, chromium and manganese;
Anticorrosive; Algae inhibitor; Preservative; Antifungal agent; Antibacterial agent; Slime control agent; Ethylenediaminetetraacetic acid (EDT
A) Chelating agents such as diethylenetriaminepentaacetic acid (DTPA), hydroxyiminodisuccinic acid (HIDS), iminodisuccinic acid (IDS), and citric acid; cleaning agents; deoxidizers; sludge dispersants; One or more of these may be added to provide a scale inhibitor.

The scale prevention method using the scale inhibitor of the present invention will be described. The scale inhibitor of the present invention may be added as it is to water systems such as a cooling water system and a boiler water system. When the scale inhibitor contains a component other than the above graft polymer, it can be added separately. When adding the scale inhibitor to the aqueous system, it is preferable to add it together with the phosphoric acid compound and / or the zinc salt. The reason is that it is possible to enhance both effects of preventing corrosion of iron pipe used as a flow path of the water system and preventing adhesion of scale. Phosphoric acid compounds include polymerized phosphoric acid (salt), phosphoric acid (salt), phosphonic acids (salts) and the like, and zinc salts include zinc nitrate, zinc phosphate, zinc chloride and the like. The scale inhibitor of the present invention is preferably added in a total amount of 0.5 to 50 ppm with a phosphoric acid compound and / or a zinc salt.

The scale inhibitor of the present invention is particularly effective in preventing and removing scales of calcium phosphate and zinc hydroxide. However, calcium carbonate, barium sulfate, calcium sulfate, calcium sulfite, calcium silicate,
It can also be used to prevent and remove other scales such as magnesium silicate, magnesium hydroxide, zinc phosphate, basic zinc carbonate, silica, iron salts and the like.

The water-soluble graft polymer according to the present invention will be described. The water-soluble graft polymer according to the present invention is obtained by graft-polymerizing a monoethylenically unsaturated monomer component (B) to a polyether compound (A) having a number average molecular weight of less than 200 without using a solvent. It is important that a solvent is not used when graft-polymerizing the water-soluble graft polymer of the present invention, that is, that the graft polymerization is performed substantially without a solvent. This is because the use of water or an organic solvent such as alcohol or toluene decreases the grafting efficiency of the monomer component (B) onto the polyether compound (A). Further, when the graft polymer is converted to an aqueous solution of an alkali salt, turbidity may occur or phase separation may occur. When a solvent is used for the addition of the polymerization initiator or the monomer component (B), it is preferable to reduce the amount as much as possible. Must be distilled off immediately.

As the polyether compound (A) and the monoethylenically unsaturated monomer component (B) which are the raw materials of the water-soluble graft polymer of the present invention, those exemplified above can be used in the same manner. The conditions for the graft polymerization can be the same as those described above. However, no solvent is used. The water-soluble graft polymer of the present invention includes, in addition to the scale inhibitor described above, a detergent builder, a fiber treating agent, a pigment dispersant, an organic-inorganic solid particle dispersant, a papermaking auxiliary, a compatibilizer, and the like. Can be used as

[0040]

The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto. Experimental Example 1 A glass reactor equipped with a thermometer, a stirrer, a nitrogen inlet tube, and a reflux condenser was charged with 120 parts by weight of polyethylene glycol having a number average molecular weight of 150 and 41.4 parts by weight of maleic acid. Heat to dissolve and stir at 128 ° C
Temperature. Next, while maintaining the temperature at 128 ± 2 ° C., 38.6 parts by weight of acrylic acid and 4 parts by weight of t-butylperoxybenzoate were separately added dropwise continuously over 2 hours, and thereafter stirring was continued for 60 minutes. Graft polymer 1 was obtained. Experimental Example 2 120 parts by weight of polyethylene glycol having a number average molecular weight of 130 (a mixture of diethylene glycol, triethylene glycol and tetraethylene glycol) was placed in a glass reactor equipped with a thermometer, a stirrer, a nitrogen inlet tube, and a reflux condenser, and maleic acid. 41.4 parts by weight were charged, dissolved by heating under a nitrogen stream, and heated to 128 ° C. with stirring.
Next, while maintaining the temperature at 128 ± 2 ° C., the acrylic acid 3
8.6 parts by weight and 4 parts by weight of t-butyl peroxybenzoate were separately dropped continuously over 2 hours, and thereafter, stirring was continued for 60 minutes to obtain a graft polymer 2. Experimental Example 3 100 parts by weight of polyethylene glycol having a number average molecular weight of 200 and 20 parts by weight of maleic acid were charged into a glass reactor equipped with a thermometer, a stirrer, a nitrogen inlet tube, and a reflux condenser, and heated under a nitrogen stream. Then, the mixture was heated to 145 ° C. with stirring. Next, while maintaining the temperature at 145 to 147 ° C., 75 parts by weight of acrylic acid and 1.5 parts by weight of di-t-butyl peroxide were separately dropped continuously over 1 hour, and then stirring was continued for 90 minutes. Thus, a graft polymer 3 was obtained. Experimental Example 4 100 parts by weight of phenoxy polyethylene glycol having a number average molecular weight of 300 and 20 parts by weight of maleic acid were charged into a glass reactor equipped with a thermometer, a stirrer, a nitrogen inlet tube, and a reflux condenser, and heated under a nitrogen stream. To dissolve and stir 1
The temperature was raised to 45 ° C. Next, while maintaining the temperature at 145 to 147 ° C., 70 parts by weight of acrylic acid and 2.5 parts by weight of di-t-butyl peroxide were separately dropped continuously over 1 hour, and thereafter, stirring was continued for 80 minutes. Thus, a graft polymer 4 was obtained. Experimental Example 5 A glass reactor equipped with a thermometer, a stirrer, a nitrogen inlet tube, and a reflux condenser was charged with 100 parts by weight of monomethoxy polyethylene glycol having a number average molecular weight of 2000 and 5 parts by weight of maleic acid. The mixture was heated and dissolved, and the temperature was raised to 145 ° C. with stirring. Next, the temperature was set to 145 to 147 ° C.
, 25 parts by weight of acrylic acid and 2.5 parts by weight of di-t-butyl peroxide were separately dropped continuously over 1 hour, and then stirring was continued for 60 minutes to obtain a graft polymer 5. Experimental Example 6 120 parts by weight of methoxypolyethylene glycol having a number average molecular weight of 160 and 34.9 maleic anhydride were placed in a glass reactor equipped with a thermometer, a stirrer, a nitrogen inlet tube, and a reflux condenser.
8 parts by weight and 60 parts by weight of water were charged, dissolved by heating under a nitrogen stream, and heated to 128 ° C. with stirring. Next, while maintaining the temperature at 128 ± 2 ° C., 38.6 parts by weight of acrylic acid and 4 parts by weight of t-butylperoxybenzoate were separately added dropwise continuously over 2 hours, and thereafter stirring was continued for 60 minutes. Graft polymer 6 was obtained. Example 1 (Calcium phosphate scale prevention test) In a 200 cc glass container with a lid, 164 g of pure water, 0.1
10% aqueous sodium hydrogen phosphate dodecahydrate 10 ml,
10 ml of 0.73% calcium chloride dihydrate aqueous solution,
6 ml of a 0.1% aqueous graft polymer solution and 10 ml of a 0.2% aqueous sodium hydrogen carbonate solution were added, and the pH was adjusted to 8.5 using a 0.1 N aqueous sodium hydroxide solution. The glass container was capped and allowed to stand at 60 ° C. and 20 hours. After cooling with running water for 15 minutes, the mixture was filtered through a 0.45 micron membrane filter, and the phosphorus concentration of the filtrate was measured by ICP analysis.

The same measurement was carried out for a system containing no graft polymer, and the scale inhibition rate of calcium phosphate was determined by the following calculation method. The results are shown in Table 1.

[0042]

(Equation 1)

Example 2 (Scale prevention test of zinc hydroxide) Into a 200 cc glass container with a lid, 160 g of pure water, 0.0
10 ml of a 4% aqueous solution of zinc nitrate hexahydrate, 10 ml of a 0.73% aqueous solution of calcium chloride dihydrate, 10 ml of a 0.1% aqueous solution of a graft polymer, and 10 ml of a 0.2% aqueous solution of sodium bicarbonate are added. The pH was adjusted to 8.5 using an aqueous sodium oxide solution. Cover the glass container,
It was left still at 60 ° C. and 20 hours. Then 15 minutes with running water
After cooling for one minute, the solution was filtered through a 0.45 micron membrane filter, and the zinc concentration of the filtrate was measured by ICP analysis.

The same measurement was performed for a system containing no graft polymer, and the scale inhibition rate of zinc hydroxide was determined by the following calculation method. The results are shown in Table 1.

[0045]

(Equation 2)

[0046]

[Table 1]

Example 3 The aqueous solution of each graft polymer was neutralized with sodium hydroxide, and the pH of the aqueous solution was adjusted to 8.5. Turbidity was observed only in the graft polymer 6, and the phase was separated when allowed to stand.

[0048]

The scale inhibitor of the present invention is easy to produce, and according to the scale prevention method using such a scale inhibitor, it is particularly effective in controlling the scale of calcium phosphate and zinc hydroxide. The water-soluble graft polymer of the present invention is an excellent polymer which is not turbid and does not cause phase separation when converted to an aqueous alkali salt solution, and is useful as a scale inhibitor and the like.

Claims (8)

[Claims] 1. A polyether compound (A) having at least one repeating unit represented by the following general formula: —CH ₂ —CH ₂ —O— in one molecule and having a number average molecular weight of less than 200 is unsaturated. A water-soluble graft polymer obtained by graft-polymerizing a monoethylenically unsaturated monomer component (B) containing a carboxylic acid monomer as an essential component without using a solvent. 2. The water-soluble graft polymer according to claim 1, which has a hydroxyl value of 30 mg KOH / g or more and an acid value of 50 mg KOH / g or more. 3. A polyether compound (A) having at least one repeating unit represented by the following general formula: —CH ₂ —CH ₂ —O— in one molecule and having a number average molecular weight of less than 200 is unsaturated. A scale inhibitor comprising a polymer obtained by graft polymerization of a monoethylenically unsaturated monomer component (B) containing a carboxylic acid monomer as an essential component,
A scale inhibitor, wherein the polymer has a hydroxyl value of 200 mgKOH / g or more and an acid value of 100 mgKOH / g or more. 4. The scale inhibitor according to claim 3, wherein the polyether compound (A) is any one of a polyalkylene glycol, an alkoxypolyalkylene glycol, and an aryloxy polyalkylene glycol. 5. A monoethylenically unsaturated monomer component (B)
A sulfonic acid group-containing monomer and / or a hydroxyl group-containing monomer are used as at least a part of the above.
A scale inhibitor as described. 6. A calcium phosphate scale inhibitor comprising the scale inhibitor according to claim 3. 7. A zinc hydroxide scale inhibitor comprising the scale inhibitor according to claim 3. 8. A scale prevention method comprising adding the scale inhibitor according to claim 3 and a phosphoric acid compound and / or a zinc salt to a total of 0.5 to 50 ppm of an aqueous system.