JP3088085B2 - Scale inhibitor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a scale inhibitor.

[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, etc., deposits (scale) of calcium carbonate, calcium phosphate, zinc hydroxide, magnesium silicate, etc. are formed on the inner wall. They may adhere, which may cause various operational obstacles such as a decrease in thermal efficiency and local corrosion.

Hitherto, polymers such as copolymer salts of acrylic acid, maleic acid and 2-hydroxyethyl methacrylate have been known as scale inhibitors (Japanese Patent Publication No. 54-29315).

[0004]

However, in order to make use of water resources more efficient, water having a high concentration ratio is used as circulating water. Recently, a high scale-inhibiting effect has been required of a scale inhibitor. Has been
It is difficult for such conventional polymers to meet the criteria.

Accordingly, an object of the present invention is to provide a novel scale inhibitor having a high scale preventing effect.

[0006]

Means for Solving the Problems As a result of intensive studies by the present inventors, a monoethylenically unsaturated monomer was substantially dissolved in a polyether compound having ethylene oxide as a structural unit.
When grafting is carried out without using a polymer, the graft ratio can be increased, and it has been found that a scale inhibitor containing such a graft polymer exhibits a high scale preventing effect.

That is, the scale inhibitor according to the present invention comprises a polyether compound (A) having a number average molecular weight of 200 or more and having a constitutional unit of ethylene oxide of 80 mol% or more.
Monoethylenically unsaturated monomer component (B) is substantially dissolved in
It is characterized by containing a water-soluble graft polymer obtained by graft polymerization without using a medium . In the above, the monoethylenically unsaturated monomer component (B) contains (meth) acrylic acid (b1) in an amount of 40 to 100 mol% and another copolymerizable monoethylenically unsaturated monomer (b2) in an amount of 0 to 60 mol. %
It preferably comprises

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The polyether compound (A) used in the present invention contains ethylene oxide in an amount of 80 mol.
% Or more having a number average molecular weight of 200 or more as a constitutional unit, and can be obtained by polymerizing ethylene oxide and, if necessary, another alkylene oxide by a known method starting from water or an alcohol. Examples of the alcohol for obtaining the polyether compound (A) include primary alcohols having 1 to 22 carbon atoms such as methanol, ethanol, n-propanol and n-butanol; secondary alcohols having 3 to 18 carbon atoms; Tertiary alcohols such as butanol; diols such as ethylene glycol, diethylene glycol, propanediol, butanediol, and propylene glycol; triols such as glycerin and trimethylolpropane; and polyols such as sorbitol. Other alkylene oxides copolymerizable with ethylene oxide are not particularly limited, but propylene oxide and butylene oxide are preferred. Further, the content of other alkylene oxide copolymerizable with ethylene oxide must be less than 20 mol% of the whole. When it is at least 20 mol%, the graft ratio of the obtained graft polymer will decrease. Further, as the polyether compound (A), the hydroxyl groups at all or some of the terminals of the polyether obtained as described above may be substituted with fatty acids having 2 to 22 carbon atoms, succinic acid, succinic anhydride, and maleic acid. And those esterified with dicarboxylic acids such as maleic anhydride and adipic acid.

The molecular weight of the polyether compound (A) is 20
0 or more, preferably 500 or more, more preferably 1000 or more. The upper limit of the molecular weight is not particularly limited, but is preferably 20,000 or less. When the polyether has two or more hydroxyl groups, the molecular weight is preferably 6,000 or less. When the molecular weight is less than 200, there is a problem that polyether not grafted increases.

The monoethylenically unsaturated monomer (B) used in the present invention includes (meth) acrylic acid (b1) and other copolymerizable monoethylenically unsaturated monomers (b).
It is preferable to use 2). (Meth) acrylic acid (b
Other monoethylenically unsaturated monomers (b2) copolymerizable with 1) include maleic acid; fumaric acid; maleic anhydride; alkyl esters of maleic acid such as dimethyl maleate and diethyl maleate; Alkyl esters of fumaric acid such as dimethyl dimethyl and diethyl fumarate; methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, stearyl (meth)
Alkyl (meth) acrylates such as acrylates; hydroxyalkyl (meth) acrylates such as hydroxyethyl (meth) acrylate and hydroxypropyl (meth) acrylate; alkenyl acetates such as vinyl acetate; aromatic vinyls such as styrene; ) Acrylonitrile, (meth) acrolein, (meth) acrylamide; dialkylaminoethyl (meth) acrylates such as dimethylaminoethyl (meth) acrylate;
Acrylamide-2-methylpropanesulfonic acid and the like can be mentioned, and one or more of these can be used. Among these, maleic acid, fumaric acid, and maleic anhydride are preferable from the viewpoint of increasing the carboxylic acid density of the graft polymer and increasing the polyvalent metal ion chelating ability and dispersing ability.

The copolymerization ratio of (meth) acrylic acid (b1) and another copolymerizable monoethylenically unsaturated monomer (b2) is (b1) 40 to 100 mol%, and (b2) is 0%. Preferably, it is ｍｏｌ60 mol%. Monomer (b
When 2) is a monomer having no carboxyl group,
As for the copolymerization ratio, (b1) is 80 to 100 mol%,
2) is preferably 0 to 20 mol%. When the monomer (b2) is a monomer having no carboxyl group, if the content of (meth) acrylic acid is less than 80 mol%, the carboxylic acid density of the obtained graft polymer is low, and the polyvalent metal ion chelate is obtained. Performance, dispersibility, etc., are not easily satisfied. (B
In the case where 2) is a carboxyl group-containing monomer such as maleic acid, fumaric acid, or maleic anhydride, even if the amount of (meth) acrylic acid is less than 40 mol%, the carboxylic acid density of the obtained graft polymer is reduced. However, in this case, if the content of (meth) acrylic acid is less than 40 mol%, the rate of introduction of maleic acid, fumaric acid, maleic anhydride, etc. into the graft polymer decreases, and the amount of remaining monomers increases. There is.

In the present invention, the ratio of the monoethylenically unsaturated monomer (B) to the polyether compound (A) is not particularly limited. However, if a high scale suppression ratio is desired, the ratio is set to 25% by weight or more. be able to. In the present invention, 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 ketone peroxides such as methyl ethyl ketone peroxide and cyclohexanone peroxide; t-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, 2,5-dimethylhexane- 2,5-dihydroperoxide,
Hydroperoxides such as 1,1,3,3-tetramethylbutyl hydroperoxide; di-t-butyl peroxide, t-butylcumyl peroxide, dicumyl peroxide, α, α′-bis (t- Dialkyl peroxides such as butylperoxy) p-diisopropylbenzene and α, α′-bis (t-butylperoxy) p-isopropylhexyne; t-butylperoxyacetate, t-butylperoxylaurate, −
Peroxyesters such as butylperoxybenzoate, di-t-butylperoxyisophthalate, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, t-butylperoxyisopropyl carbonate; n-butyl Peroxyketals such as -4,4-bis (t-butylperoxy) valerate and 2,2-bis (t-butylperoxy) butane; diacyl peroxides such as dibenzoyl peroxide;

The amount of the polymerization initiator is not particularly limited, but is preferably 0.1 to 15% by weight, more preferably 0.5 to 10% by weight, based on the monoethylenically unsaturated monomer component (B). It is. If the amount is less or more than this, the grafting efficiency to the polyether compound (A) decreases. The polymerization initiator can be added to the polyether compound (A) in advance, but can also be added simultaneously with the monoethylenically unsaturated monomer component (B).

The graft polymerization is carried out substantially without solvent.
You. When water or an organic solvent such as alcohol or toluene is used, the monomer component (B) to the polyether compound (A)
Graft efficiency 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.

In the graft polymerization, the polyether compound (A) is preferably initially charged in part or in its entirety. When maleic acid, fumaric acid, or maleic anhydride is used as the (meth) acrylic acid (b1) and the other copolymerizable monomer (b2), at least half of (b2) is preliminarily polymerized. Mix with ether compound (A) and add 100
After heating at a temperature of not less than ° C., it is preferable to add the remaining monomer components and the polymerization initiator separately and 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 greatly improved.

The graft polymer obtained as described above can be used as a scale inhibitor as it is, but may be used by adding various additives if necessary. The scale inhibitor of the present invention is used in water systems such as cooling water systems, boiler water systems, seawater desalination equipment, pulp dissolving pots, black liquor concentrating pots, etc.
What is necessary is just to add as it is. When the scale inhibitor contains a component other than the above graft polymer, it can be added separately.

The scale inhibitor of the present invention can be used for preventing or removing scale such as calcium carbonate, calcium phosphate, zinc hydroxide, silicate, silica, iron and the like.

[0020]

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. Synthesis Example 1 70 parts by weight of monomethoxypolyethylene glycol having an average molecular weight of 2000 and 13.9 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 then charged under a nitrogen stream. Heat, melt and mix,
The temperature was raised to 145 ° C. with stirring. Next, the temperature was set to 145 to 1
While maintaining at 47 ° C., 19 parts by weight of acrylic acid, di-t-
1.7 parts by weight of butyl peroxide were separately added dropwise continuously over 1 hour, and then stirring was continued for 1 hour. After cooling, an aqueous solution of sodium hydroxide (a 10% solution) was added to the mixture so as to have a pH of about 11 with stirring, and the mixture was heated at reflux temperature for 1 hour to obtain an aqueous sodium salt of the graft polymer 1. Synthesis Example 2 70 parts by weight of monomethoxypolyethylene glycol having an average molecular weight of 2,000 and 11.8 parts by weight of maleic acid were charged into a reactor similar to that of Synthesis Example 1, and heated and melted and mixed under a nitrogen stream, and then stirred 140 The temperature was raised to ° C. Next, while maintaining the temperature at 140 to 142 ° C, acrylic acid 20.4
Parts by weight and 1.6 parts by weight of di-t-butyl peroxide were separately dropped continuously over 1 hour, and then stirring was continued for 30 minutes. After cooling, aqueous sodium hydroxide solution (1
0% solution) with stirring to an amount of about pH 11,
The mixture was heated at the reflux temperature for 1 hour to obtain an aqueous sodium salt solution of the graft polymer 2. Synthesis Example 3 70 parts by weight of monomethoxypolyethylene glycol having an average molecular weight of 2,000 and 13.9 parts by weight of maleic acid were charged into a reactor similar to that of Synthesis Example 1, heated and melted and mixed under a nitrogen stream, and then stirred at 145%. The temperature was raised to ° C. Next, while maintaining the temperature at 145 to 146 ° C., acrylic acid 20.4
Parts by weight and 1.6 parts by weight of di-t-butyl peroxide were separately dropped continuously over 2 hours, and then stirring was continued for 30 minutes. After cooling, aqueous sodium hydroxide solution (1
0% solution) with stirring to an amount of about pH 11,
The mixture was heated at the reflux temperature for 1 hour to obtain an aqueous sodium salt solution of the graft polymer 3. Examples 1 to 3 170 g of water was placed in a glass bottle having a capacity of 225 ml.
10 g of a 56% calcium chloride dihydrate aqueous solution, and 0.1 g of the graft polymers 1 to 3 obtained in the above Synthesis Examples 1 to 3.
3 g of a 02% aqueous solution was mixed, and 10 g of a 3% aqueous sodium bicarbonate solution and 7 g of water were added to make a total amount of 200 g. The obtained 530 ppm supersaturated aqueous solution of calcium carbonate was sealed and heated at 70 ° C. for 3 hours. After cooling, the precipitate was filtered through a membrane filter having a pore size of 0.1 μm, and the filtrate was analyzed in accordance with JIS K0101. The calcium carbonate inhibition rate (%) was determined by the following equation. The results are shown in Table 1.

Scale inhibition rate (%) = (CB) / (A
-B) × 100 A: The concentration of calcium dissolved in the liquid before the test B: The concentration of calcium in the filtrate, which was tested without the addition of a scale inhibitor C: The concentration of calcium in the filtrate after the test

[0022]

[Table 1]

[0023]

The scale inhibitor of the present invention is a novel scale inhibitor having a high scale preventing effect.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-177406 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C02F 5/10-5/14 C08F 283 / 06 C08L 51/08 C11D 7/22-7/46 F28F 19/00

Claims (2)

(57) [Claims] 1. A monoethylenically unsaturated monomer component (B) is added to a polyether compound (A) having a number average molecular weight of 200 or more containing ethylene oxide as a constitutional unit in an amount of 80 mol% or more.
A scale inhibitor comprising a water-soluble graft polymer obtained by graft polymerization substantially without using a solvent . 2. Monoethylenically unsaturated monomer component (B)
Is (meth) acrylic acid (b1) 40 to 100 mol%
The scale inhibitor according to claim 1, comprising 0 to 60 mol% of another copolymerizable monoethylenically unsaturated monomer (b2).