JPS602918B2 - Anti-scale agent - Google Patents

Description

[Detailed description of the invention] This invention relates to scale inhibitors.

Specifically, the present invention relates to a scale inhibitor containing an organic synthetic polymer as an active ingredient. Scale formation has become a problem in various industrial water systems.

Most industrial water is used for heat exchange such as cooling and heating, so it is hot and comes into contact with heat transfer surfaces, which tends to cause scale.Especially when water containing a large amount of hardness components is used, When alkali or alkaline earth metal compounds enter the water system due to internal operation or environmental reasons, or when the concentration of phosphate ions or heavy metal ions in the water system increases due to the use of anticorrosives, etc., there is always a problem of scale generation. Typical examples of these scales include calcium carbonate scale, calcium phosphate scale, zinc scale, etc. Among these scales, various effective scale inhibitors have already been proposed and used for calcium carbonate scale. However, there are few effective scale inhibitors for calcium phosphate scale, lead noise scale, etc., and even if there are scale inhibitors that are effective for each of the scales mentioned above, there are almost no known ones that are effective for all of the various scales. In view of these points, the inventors of this invention have conducted extensive research on scale inhibitors that are uniformly effective on various scales, and have found that specific organic synthetic polymers are effective as scale inhibitors. The present inventors have discovered the fact that when used as a component, the generation of calcium phosphate scale is significantly suppressed, and furthermore, the generation of various scales such as calcium carbonate scale and zinc scale is significantly suppressed. .

Thus, according to the present invention, one or more alkylolamide compounds represented by the general formula (1),
A scale inhibitor containing a copolymer with one or more alkenyl compounds represented by the general formula (0) as an active ingredient is provided.

In the above general formula (1), R and R2 are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and x has one bond or a branch having 1 to 8 carbon atoms. It is an alkylene group that can be used as an alkylene group. When X is an alkylene group, it preferably has 1 to 5 carbon atoms, and 1 to 3 carbon atoms, from the viewpoint of solubility etc.
is most preferred. Furthermore, in the above general formula (0), R
3, R4 and R5 are each independently a hydrogen atom or a methyl group, and A is a hydroxyl group or a group of -OR6 (in the formula, H is a lower alkyl group which may be substituted with one hydroxyl group) or a -N ratio Alternatively, it represents a group of -NHR7 (in the formula, R7 is a lower alkyl group which may be substituted with -S03 at its terminal). Specific examples of the alkylolamide compound of general formula (1) include N-hydroxyacrylamide, N-hydroxymethacrylamide, N-methyl-N
-Hydroxyacrylamide, N-methylolacrylamide, N-methylolmethacrylamide, N-methyl-N-methylolmethacrylamide, N-methyl-N-methylolmethacrylamide, N-ethyl-N-methylolmethacrylamide, N-ethyl-N-methylolmethacrylamide, N -Hydroxyethyl acrylamide, N
-Hydroxyethyl methacrylamide, N-methyl-N
-Hydroxyethyl acrylamide, N-ethyl-N-
Hydroxyethyl acrylamide, N-propyl-N-hydroxyethylacrylamide, N-hydroxypropylacrylamide, N-hydroxyp.

Examples include pyrmethacrylamide, N-hydroxyisopropylacrylamide, N-hydroxyisopropylmethacrylamide, and the like. Among these, N-methylol acrylamide, N-methylol methacrylamide, N
- Hee. Droxyethyl acrylamide, N-hydroxyethyl methacrylamide, etc. can be preferably used from the viewpoint of ease of synthesis and cost. Specific examples of the alkenyl compound of general formula (0) include acrylic acid, methacrylic acid, crotonic acid, incrotonic acid, Vans-2-methylcrotonic acid, 2-methylisocrotonic acid, acrylamide, methacrylamide, N-methyl Acrylamide, N-ethylacrylamide, N-propylacrylamide,
Acrylamide-N-methylpropanesulfonic acid, methyl acrylate, methyl methacrylate, methyl crotonate, ethyl acrylate, ethyl methacrylate,
Ethyl crotonate, propyl acrylate, propyl methacrylate, propyl crotonate, butyl acrylate, butyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate,
Examples include 2-hydroxypropyl methacrylate.

Among these, acrylic acid, methacrylic acid, acrylamide, methacrylamide, acrylamide N-methylpropanesulfonic acid, methyl acrylate, ethyl acrylate, hydroxyethyl acrylate, etc. can be preferably used. The organic synthetic polymer used in this invention is a copolymer obtained by subjecting one or more of the above alkylolamide compounds and one or more of the above alkenyl compounds to known polymerization conditions. and usually alki.

A suitable copolymer is one in which the alkylolamide compound is copolymerized at a monomer ratio of at least 1% by weight based on the total amount of the monomers of the alkyloamide compound and the alkenyl compound. Furthermore, if the molecular weight exceeds 100,000, aggregation occurs, which is not preferable. Therefore, those with a molecular weight of about 500 to 100,000 are suitable, and usually about 5
00 to 20,000 is preferable. These copolymers include, for example, one or more alkylolamide compounds and one or more alkenyl compounds in water, water-containing soot, or an organic solvent (e.g., lower alcohol, dioxane, aromatic polymerization initiators (e.g., inorganic and organic peroxides such as persulfates and penzoyl peroxide, azopisisobutyronitrile, redox catalysts, etc.)
It can be obtained by overflowing with.

Note that when the polymerization reaction is carried out under acidic conditions, crosslinking is likely to occur and a three-dimensional structure is likely to occur, which may reduce the solubility and dispersibility of the produced polymer. Therefore, it is desirable to carry out the polymerization reaction under alkaline conditions by adding sodium hydroxide or the like. However, no matter what structure the obtained copolymer has, the desired solubility (including when made into a salt)
, any condition can be used as long as it exhibits dispersibility. When the polymers thus obtained are used as scale inhibitors, they must be substantially water-soluble.

Therefore, if the obtained copolymer is difficult to dissolve in water,
In order to obtain the desired effect, it is desirable to increase the solubility by converting the free acid or its ester moiety in the copolymer into the corresponding salt. In this case, lithium, sodium, potassium and ammonium salts are preferred, and sodium and potassium salts are more preferred.
The copolymer of the present invention is usually used as a scale inhibitor in the form of a powder or liquid preparation.

As a liquid preparation, it is convenient and preferable to use an aqueous liquid containing the polymer bound by the above-mentioned polymerization reaction as it is as long as the solubility is satisfied. In this case, since the polymerization reaction further proceeds in the liquid preparation, it is desirable to add a polymerization inhibitor such as hydroquinoso. When using the scale inhibitor of this invention, the addition method may be exactly the same as that for ordinary scale inhibitors, and the amount added varies depending on the target aqueous system, but is usually 0.5 to 3
The purpose can be achieved by adding 00 wind.

The scale inhibitors of this invention can also be used in combination with conventional scale inhibitors such as phosphonic acids, phospho/carboxylic acids, EDT.
A, NTA, lignin sulfonic acid, poly-IJ acrylic acid,
It is also possible to use it in combination with polymaleic acid and the like.

Furthermore, the scale inhibitor of the present invention may be used in combination with a commonly used corrosion inhibitor, in which case it will not have any adverse effects on the corrosion inhibitor, and will also simultaneously exhibit the effect of preventing scale caused by the corrosion inhibitor itself. Therefore, more favorable results can be obtained.

In this case, examples of the anticorrosive agent used in combination include polymerized phosphates, salts of heavy metals such as zinc, manganese, and nickel, molybdates, oxycarboxylate salts, and the like. The scale inhibitor of the present invention is effective in preventing not only calcium carbonate scale, but also calcium phosphate scale and zinc scale, and is also effective in preventing the occurrence of various other scales.

Therefore, it is effective in preventing the generation of not only single scales but also multicomponent scales in various industrial water systems, making it an industrially useful agent. Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereby.

Example 1 Copolymers having the monomer compositions shown in Table 1 were synthesized by known methods, and a pentacalcium carbonate scale prevention test was conducted using these copolymers.

The molecular weight of each polymer is estimated by the viscosity method.Table 1 (Test method) Calcium ion 10Q cape and sodium bicarbonate
It was added to pure water to give an alkalinity of 600 to a test solution.

Each of the above compounds was added to the test solution 1 to a predetermined concentration, and the mixture was stirred for 2 hours at 20 pm using a magnetic stirrer while maintaining the temperature at 50 pm. Next, the test liquid was sifted with furnace paper (Toyoguchi M.6), and the calcium ion concentration of the furnace liquid was measured. The amount of calcium ions precipitated during the test was determined from the difference in calcium ion concentration in the test solution before and after the test, and from this the amount of calcium carbonate (CaC03) scale deposited per 1 test solution was calculated.

The results are shown in Table 2.

As a comparative example, polyacrylic acid (molecular weight approximately 5000
) are also shown. Table 2 Example 2 A calcium phosphate scale prevention test was conducted using 3 times more concentrated Osaka city water.

Table 3 shows the quality of the water used. Table 3 PH 7.5
0 electrical conductivity (rs/enemy) 750p alkalinity (willow) OM alkalinity (chest)
61.5 Calcium hardness (legs)
■86 total hardness (legs)
157.0 sulfate ions (pieces) 3
9.5 Chlorine ions (skin) 691 SiQ (legs) 10.5 Total iron (
Skin) 0.5 Sodium hexametaphosphate was added as POJ to 0.5 of the above concentrated water, and 204 of sodium monophosphate was added as POJ to give the respective compounds used in Example 1 a predetermined concentration. While keeping the temperature at 50° C., koji-azusa was continued for 24 hours at 10 pm using a koji-azusa machine.

Thereafter, the amounts of precipitated calcium ions and total phosphoric acid were determined in the same manner as in Examples, and the sum was defined and calculated as a calcium phosphate scale. The results are shown in Table 4.

Table 4 Table 5 Example 3 The scale prevention effect when the scale inhibitor of this invention and various anticorrosive agents were used together was tested.

One volume of the 3-fold concentrated water of Example 2 was used as the water used, and each compound was added thereto at a predetermined concentration. A mild steel plate (SPCC; 30 x 50 x 1 side) is suspended on a stainless steel frame twill, and the mild steel plate is immersed in a solution, and while keeping the temperature at 50°C, the mild steel plate is heated at 10 pm for 5 minutes. The lantern worship continued for days. Magnesium, calcium, zinc and total phosphate ions after the test were measured in the same manner as in Example 1, and the total was taken as the amount of precipitated ions per test solution.

Note that results using sodium polyacrylate are also shown as a comparative example. These results are shown in Table 5.

Claims (1)

[Claims] 1 General formula (I): ▲ Numerical formula, chemical formula, table, etc. ▼ (In the formula, R_1 and R_2 are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms; X is 1 one or more alkylolamide compounds represented by an alkylene group (optionally having two bonds or a branch with 1 to 8 carbon atoms), and general formula (II): ▲ Numerical formula, chemical formula, table, etc. ▼ [In the formula, R_3, R_4 and R_5 are each independently a hydrogen atom or a methyl group; A is a hydroxyl group or -OR
_6 (in the formula, R_6 is a lower alkyl group optionally substituted with one hydroxyl group) or -NH_2 or -N
A scale containing as an active ingredient a copolymer with one or more alkenyl compounds represented by HR_7 (in the formula, R_7 is a lower alkyl group whose terminal may be substituted with -SO_3H) Inhibitor. 2 The alkylolamide compound of general formula (I) is N-
Hydroxyacrylamide, N-hydroxymethacrylamide, N-methyl-N-hydroxyacrylamide,
N-methylolacrylamide, N-methylolmethacrylamide, N-methyl-N-methylolmethacrylamide, N-methyl-N-methylolmethacrylamide, N
-Ethyl-N-methylol acrylamide, N-ethyl-N-methylol methacrylamide, N-hydroxyethyl acrylamide, N-hydroxyethyl methacrylamide, N-methyl-N-hydroxyethylacrylamide, N-ethyl-N-hydroxyethylacrylamide , N-propyl-N-hydroxyethylacrylamide, N-hydroxypropylacrylamide, N-hydroxypropylmethacrylamide, N-hydroxyisopropylacrylamide, or N-hydroxyisopropylmethacrylamide. agent. 3. Claim 1 or 2, wherein the alkylolamide compound of general formula (I) is N-methylol acrylamide, N-methylol methacrylamide, N-hydroxyethyl acrylamide, or N-hydroxyethyl methacrylamide. scale inhibitor. 4 The alkenyl compound of general formula (II) is acrylic acid,
Methacrylic acid, crotonic acid, isocrotonic acid, tran
s-2-methylcrotonic acid, 2-methyl-isocrotonic acid, acrylamide, methacrylamide, N-methylacrylamide, N-ethylacrylamide, N-propylacrylamide, acrylamide-N-methylpropanesulfonic acid, methyl acrylate, methyl methacrylate, Methyl crotonate, ethyl acrylate, ethyl methacrylate, ethyl crotonate, propyl acrylate, propyl methacrylate, propyl crotonate, butyl acrylate, butyl methacrylate, 2
The scale inhibitor according to any one of claims 1 to 3, which is -hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, or 2-hydroxypropyl methacrylate. 5 The alkenyl compound of general formula (II) is acrylic acid,
The scale inhibitor according to any one of claims 1 to 4, which is methacrylic acid, acrylamide, methacrylamide, acrylamide-N-methylpropanesulfonic acid, methyl acrylate, ethyl acrylate, or hydroxyethyl acrylate. 6 Claims in which the copolymer is obtained by subjecting it to copolymerization at a monomer ratio such that the total amount of the alkylolamide compound is at least 10% by weight based on the total amount of monomers before polymerization. The scale inhibitor according to any one of Items 1 to 5. 7. The scale inhibitor according to any one of claims 1 to 6, wherein the copolymer has a molecular weight of about 500 to 100,000. 8. The scale inhibitor according to any one of claims 1 to 7, wherein the copolymer has a molecular weight of about 500 to 20,000.