JPS63258697A - Corrosion inhibitor that also suppresses the scale of metals in water systems - Google Patents

Abstract

PURPOSE:To effectively suppress scale, by using a polymer consisting of water- soluble org. phosphonic acid having a carbon-phosphorus bond, a water-soluble zinc salt and a specific monoethylenic unsaturated sulfonic acid monomer. CONSTITUTION:Water-soluble org. phosphonic acid such as 2- phosphonobutane-1,2,4-tricarboxylic acid or 1-phosphonopropane-2,3-dicarboxylic acid, a water-soluble zinc salt (e.g., zinc chloride, zinc sulfate) and a monoethylenic unsaturated sulfonic acid monomer (e.g., 2-acrylamide-2- methylpropanesulfonic acid, 2-methacrylamide-2-methylpropanesulfonic acid) are copolymerized along with acrylic acid to form copolymer. The wt. average MW of this copolymer is pref. 10<3>-10<5>. This copolymer is used as a scale inhibitor to make it possible to enhance operability.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Industrial Application Field The present invention is directed to a synergistic composition for corrosion prevention that also serves as scale control for metal materials such as heat exchangers and piping in aqueous systems including cooling water systems. Regarding.

B. Conventional Technology Various water treatment agents are used to prevent corrosion of metal materials and suppress scale in water systems such as cooling water systems. Among these water treatment agents, chromate,
Heavy metal salts such as zinc salts and phosphoric acid compounds are used, but the use of chromate salts has been restricted in recent years to prevent pollution, and the concentration of zinc salts in wastewater has also been restricted.

Among phosphoric acid compounds, polymerized phosphoric acids are easily hydrolyzed in water systems, so they easily turn into scales such as calcium phosphate, and if wastewater is discharged without any treatment, it causes eutrophication of lakes and oceans and disturbs the ecosystem. becomes.

Therefore, instead of polymerized phosphoric acids, phosphonic acids have recently been frequently used because they are less susceptible to hydrolysis in aqueous systems and are less likely to scale, and because they can reduce the phosphorus concentration in wastewater.

It is thought that these phosphonic acids react with calcium in water to form a metal protective film of calcium phosphonate, exhibiting an anti-corrosion effect, but phosphonic acids alone do not have sufficient anti-corrosion properties, so zinc salts etc. are added. This strengthens the anti-corrosion ability.

Furthermore, phosphonic acids are known to have the effect of suppressing calcium carbonate scale at low concentrations. Phosphonic acids commonly used in cooling water systems include l-hydroxyethylidene-1,1-diphosphonic acid, 2-hydroxyphosphonoacetic acid, aminotrimethylenephosphonic acid, and 2-hydroxyethylidene-1,1-diphosphonic acid.
Examples include phosphonobutane-1,2,4-tricarboxylic acid. Although these phosphonic acids have excellent anticorrosion effects,
Due to the increase in pH and hardness components, there is a tendency to react with calcium and zinc ions in water and precipitate as calcium phosphonate and zinc phosphonate, reducing the effective concentration of phosphonic acid and zinc in water, resulting in corrosion prevention and scale inhibiting power. may no longer be displayed.

C9 Problems to be Solved by the Invention An object of the present invention is to solve the above-mentioned drawbacks and problems.

The present inventors have completed the present invention as a result of intensive research on improving the anticorrosive effect when using phosphonic acids and zinc salts together, methods for inhibiting scale and staining, and synergistic compositions. did it. That is, the purpose of the present invention is to provide corrosion prevention that also serves as scale control for metals in aqueous systems that can prevent scale deposition caused by the reaction of phosphonic acid with calcium and zinc ions in water, as well as the precipitation and deposition of other poorly soluble salts in water. An object of the present invention is to provide a water treatment composition that does not require any pH control by adding an acid to prevent scaling.

Means for Solving Problem D2 The corrosion inhibitor of the present invention contains (1) at least one water-soluble organic phosphonic acid having a carbon-phosphorous bond and (2) at least one water-soluble zinc salt.
species and (3) a monoethylenically unsaturated sulfonic acid monomer represented by the following formula IRz? C= CHI? , -9O,H (in the formula, l, , R1 each independently represent hydrogen or a methyl group, and cannot be a methyl group at the same time, and R5 is represented by the following formula: In the formula, X I, X t each independently represents hydrogen, a hydroxyl group, or a methyl group, and n represents an integer from 1 to 3.)
It is composed of a polymer (including homopolymers and copolymers) consisting of as an essential monomer as an active ingredient.

The water-soluble organic phosphonic acids having a carbon-phosphorus bond used in the present invention include 2-phosphonobutane-1,2,
4-) dicarboxylic acid, 1-phosphonopropane-2,3-
Dicarboxylic acid, phosphonosuccinic acid, α-methylphosphonosuccinic acid, phosphonocarboxylic acids such as 1-phosphonopropane-1,2,3-tricarboxylic acid, aminotrimethylenephosphonic acid, ethylenediaminetetramethylenephosphonic acid, hexa Aminophosphonic acids such as methylenediaminetetramethylenephosphonic acid, diethylenetriaminepentamethylenephosphonic acid, l-hydroxyethylidene-1,1-disulfonic acid, 1-hydroxypropylidene-
Examples include hydroxy-substituted lower alkylenephosphonic acids such as 1,1-disulfonic acid and 2-hydroxyphosphonoacetic acid. The most preferred water-soluble organic phosphonic acids are 2-
They are phosphonobutane-1,2,4-tricarboxylic acid, 1-hydroxyethylidene-1,1-disulfonic acid, 2-hydroxyphosphonoacetic acid, and aminotrimethylenephosphonic acid. The water-soluble organic phosphonic acids used in the present invention refer to phosphonic acids and water-soluble salts thereof. The water-soluble salt mentioned here means that some or all of the protons of the phosphoric acid group and/or nine-carboxyl group are alkali metal,
Substituted with alkaline earth metals, zinc, ammonia, and/or amines, etc., and soluble at the concentration used.

Two or more types of water-soluble organic phosphonic acids may be used in combination.

The present inventors surprisingly discovered that 1-hydroxyethylidene-1,1-diphosphonic acid and the following general formula: % formula % (wherein R is H, CH3, or CHf-CH!-00
It has been found that a mixture with phosphonocarboxylic acid represented by .

The most preferred example of the phosphonocarboxylic acids is 2-
Phosphonobutane-1,2,4-toIJcarphonic acid is mentioned.

The zinc compound used in the present invention may be any compound as long as it dissolves at the concentration used in the zinc aqueous system and releases zinc ions, but preferably zinc chloride, zinc sulfate,
Examples include zinc nitrate, zinc acetate, zinc malate, and zinc citrate.

Examples of the monoethylenically unsaturated sulfonic acid monomer in the polymer used in the present invention include 2-acrylamido-2-methylpropanesulfonic acid, 2-methacrylamido-2-methylpropanesulfonic acid, and sulfopropylacrylic acid. , sulfopropyl methacrylic acid, 3-acryloxy-1,2-dihydroxypropanesulfonic acid, 3-
Methacryloxy-1,2-dihydroxypropanesulfonic acid, 3-allyloxy-1,2-dihydroxypropanesulfonic acid, 3-allyloxy-2-hydroxypropanesulfonic acid, 3-methacryloxy-2-hydroxypropanesulfonic acid, and water solutions thereof Examples include salts.

Further, as copolymerization components in the copolymer with the monoethylenically unsaturated sulfonic acid monomer, carboxylic acids such as acrylic acid, maleic acid, maleic anhydride, methacrylic acid, fumaric acid, itaconic acid, and crotonic acid, acrylamide,
Amides such as methacrylamide, (meth)acrylic acid esters such as methyl (meth)acrylate and edyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-methacryloxy-1 , 2-dihydroquinepropane and other hydroxyalkyl (meth)acrylates, allyl alcohol, 3-methyl-3-buten-1-ol, 3
-Methyl-2-buten-1-ol Alcohols such as 2-methyl-3-buten-2-ol, sulfonic acids such as vinylsulfonic acid and allylsulfonic acid, methyl vinyl ether, 3-acryloxy (methacryloxy)-1, 2-
Examples include ethers such as dihydroxypropane and adal(methallyl)polyalkylene glycol.

A more preferable polymer containing the monoethylenically unsaturated sulfonic acid is a homopolymer of the monoethylenically unsaturated sulfonic acid monomer and a water-soluble salt thereof, or the monoethylenically unsaturated sulfonic acid monomer. and/or acrylamide, maleic acid (including maleic anhydride) and/or formula: %Formula% [In the formula, Rl and nt each independently represent hydrogen or a methyl group, and cannot be a methyl group at the same time. ] A copolymer containing a monomer selected from unsaturated carboxylic acids and water-soluble salts thereof, and water-soluble salts thereof.

The water-soluble salts mentioned here are salts in which some or all of the protons of sulfonic acid groups and/or carboxyl groups are substituted with alkali metals, alkaline earth metals, zinc, ammonia, and/or amines, etc., and are therefore soluble at the concentration used. refers to what is possible.

The preferred copolymerization ratio in the above copolymer is such that the total amount of monoethylenically unsaturated sulfonic acid monomer is 10 to 90%, and the total amount of unsaturated carboxylic acid monomer and acrylamide is 10 to 90%.
It is 90%.

Preferred examples of the polymer include a copolymer of acrylic acid and/or methacrylic acid and 2-acrylamido-2-methylpropanesulfonic acid, and a copolymer of acrylic acid and/or methacrylic acid and 2-methacrylamido-2-methylpropanesulfonic acid. .

Acrylic acid and/or methacrylic acid and sulfopropyl acrylic acid copolymer, acrylic acid and/or methacrylic acid and sulfopropyl methacrylic acid copolymer, acrylamide and 2-acrylamide-methylpropanesulfonic acid copolymer, acrylic acid and/or methacrylic acid and sulfopropyl methacrylic acid copolymer, Or methacrylic acid, acrylamide and 2-acrylamitomedelpropanesulfonic acid terpolymer, 2-acrylamide-methylpropanesulfonic acid homopolymer, maleic acid (anhydride) and 2-acrylamido-2-methylpropanesulfonic acid copolymer and their water-soluble salts.

The preferred molecular weight of the polymer is 1.000 to 100.0 as ff1ffi average molecular weight. There is OOOte, more preferable l
t3.000 to 30,000. Here, the weight average molecular weight is determined by gel permeability chromatography (GPC).
Using this method, polyethylene glycol, which has a known molecular bond, is measured as a substance. Outside this molecular weight range, synergistic corrosion and scale inhibiting effects will not be exhibited.

Each component of the corrosion inhibitor in the present invention is added to the system individually, or it may be added as a formulation with other compounds as necessary. These compounds and formulations are injected continuously or intermittently to maintain sufficient concentrations within the system to simultaneously achieve corrosion, scale, and fouling control.

As for the amount of water-soluble organic phosphonic acid added. , 2-30p
pm, yol) preferred tL, <ha l-10ppm, the amount of water-soluble zinc salt added is 0.2 to 30 ppm as Zn, more preferably 1 to toppm, and the amount of polymer added is 0.2 to 1
It is more preferably 0.5 to 30 ppm than 100 ppm.

It is possible to further add at least one kind of chemicals known as other corrosion inhibitors and scale inhibitors to the treatment agent in the present invention. Examples of these chemicals include chromate, ffl chromate, anhydrous chromate, orthophosphoric acid and its water-soluble salts, 1M synthetic phosphoric acid and its water-soluble salts, molybdates, tungstates, nitrites, silica. acid salt,
Organic phosphoric acid esters and their water-soluble salts, phosphinic acids and their water-soluble salts, lignylin sulfonates, tannins, water-soluble cellulose gums such as carboxymethyl cellulose and sulfonated cellulose, and citric acid.

Hydroxy acids such as malic acid, gluconic acid, glucoheptonic acid, 1,2.3-) lyazole, l.

2.3-benzotriazole, tolyltriazole (i.e. 4-methyl-1,0-benzotriazole and 5-methyl-1,8-benzotriazole), 4-carboxy-1,H-benzotriazole, 4-nitro-1
, H-benzotriazole and other triazoles, 2-
Thiazoles such as mercaptobenzodeazole, 5-chloro-2-methicaptobenzothiazole, 2-(3'-aminopropyl)-benzothiazole, 2-(2'-amino-2'-methylpropyl)-benzothiazole , 2-(5'-aminopentyl)benzimidazole, 2-(2'-amino-2'-methylpropyl)-bezimidazole, 2-ethyl-4-methyl-imidazole, 2-ethylimidazole, 2-methyl Examples include imidazoles such as imidazole.

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples.

Example 1 30! A total length of 50 cm in a test cooling water tower with a holding water capacity of
Four double-tube test heat exchangers were connected in series, and water was circulated at a flow rate of 0.5 m/s using a centrifugal pump. The material of the test heat exchanger tube was carbon 194 (J[S 5TPG, outer diameter 12.7 mm), and an electric heater was inserted inside the heat exchanger tube. Provides a heat flux of OOQ Kcal/m”, h, heats the circulating water, and increases the outlet temperature of the cooling water to 45
℃'IRN I, was. The amount of evaporated water in the cooling tower is 2. Of/
Blowdown is performed using a metering pump so that the concentration of the circulating water is constant, and the corrosion and scale inhibitor of the present invention is supplied using a chemical feeder.
The chemical a degree of the circulating water was maintained constant. The test period is 15 days. After the test was completed, the test heat exchanger tube was dried and weighed, and then the deposits were removed and weighed again. Method for judging results: Corrosion rate (MDD) - 'Ninii Miji S, xO Deposit adhesion fil (mg/cm") = "-h Here,: Pre-test type ffi of test heat exchanger tube [mg]
L-image: Mold weight after test of test heat exchanger tube [n+g]L3
= Heavy ffi after removing deposits from test heat exchanger tube
(Results are expressed as the average value of four test heat exchanger tubes.

) Sl: Surface area of test heat exchanger tube 14m"]S
t: Surface area of test heat exchanger tube [cm”lD
: Exam period [day] Test G Tsuba T: The two days of Me are Table-11 Konashi Age A Yesterday Ha 3
Initial high concentration treatment was performed at twice the concentration.

The quality of circulating water is pH 8.8, electrical conductivity 1540μS/
am.

M alkalinity 160ppm, total hardness 320ppm, C
The a hardness was 160 ppm, the phosphor content was 52 ppm, and the chlorine ion was 240 ppm.

The concentration of circulating water was 4.

The results are shown in Table-1.

+1EDP: 1-hydroxyethylidene-1,1
-diphosphonic acid 11P8; 2-hydroxyphosphonoacetic acid PBTC:
MP to 2-phosphonobutane-1,2,4-tricarboxylic acid; MPS to aminotrimethylenephosphonic acid:
2-Acrylamide-2-methylpropanesulfonic acid polymer^-8 PS: Acrylic acid/2-acrylamide-
2-methylpropanesulfonic acid copolymer, polymerization ratio 6:4 (weight) M-H + llI'S: methacrylic acid/2-acrylamide-2-methylpropanesulfonic acid copolymer, polymerization ratio 1:r (weight) AM-AMPS: Acrylamide/2-acrylamide-2-methylpropanesulfonic acid copolymer, polymerization ratio I:3 (weight) MA-AMr'S: Maleic anhydride/2-acrylamide-2-Tw: Weight average molecular weight The fffffi average molecule mπW of the union is all 10,0
00 to 20,000) (blank below) As is clear from this table, the corrosion inhibitor of the present invention containing phosphonic acid, zinc chloride, and a polymer has a Compared to comparative examples that lack either one of them, the corrosion prevention effect due to the synergistic effect of the three is remarkable.
The amount of deposits attached also decreases in inverse proportion to this effect.

Example 2 The dissolution and dispersion performance of the inhibitor in the present invention in zinc phosphonate was evaluated.

Calcium chloride, magnesium chloride in deionized water.

Test water with the following water quality was prepared by dissolving sodium hydrogen carbonate and zinc sulfate: CaVE degree 300 ppm
, Mg hardness 1501) pm, HCO* 300pp
m (as CaCOa), Zn lOppm, HE
The compounds shown in Table 2 were added to the DP 3Gppm0 test water, and the prt of the test water was adjusted to 8.5. The test liquid was placed in a sealed container and allowed to stand for 3 days in a constant temperature bath at 50°C, and then the test water was filtered through a membrane filter with a thickness of 0.45μ, and the zinc'a degree was measured by atomic absorption spectrometry.

The results are shown in Table-1.

(Table 2) Effects of the F6 invention According to the corrosion inhibitor that also serves as scale suppression of the present invention, corrosion of metal materials, particularly carbon steel heat exchangers and pipes, etc. in water systems including cooling water systems can be prevented by phosphorus. The absence of any of the acid-zinc compounds and polymers is not only achieved economically with lower phosphonic acid-free polymer and zinc concentrations compared to conventional compositions, but also the secondary This not only eliminates all the problems of scale build-up and minimizes the concentration of phosphorus and zinc in wastewater, but also eliminates the need for pH adjustment by adding acid, which improves operational efficiency. It also has a great effect on ease of use.

Patent applicant: Hakuto Chemical Co., Ltd. Representative Shigeo Takayama

Claims (1)

[Scope of Claims] 1. (1) at least one water-soluble organic phosphonic acid having a carbon-phosphorus bond, (2) at least one water-soluble zinc salt, and (3) a monoethylenic compound represented by the following formula: Unsaturated sulfonic acid monomer ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (In the formula, R^1 and R^2 each independently represent hydrogen or a methyl group, and cannot be a methyl group at the same time,
is represented by the following formula: ▲There are mathematical formulas, chemical formulas, tables, etc.▼ In the formula, X_1 and X_2 each independently represent hydrogen, a hydroxyl group, or a methyl group, and n represents an integer from 1 to 3. ) as an essential monomer (including homopolymers and copolymers) as an effective ingredient. agent. 2. Water-soluble organic phosphonic acids include 1-hydroxyethylidene-1,1-diphosphonic acid, 2-hydroxyphosphonoacetic acid, 2-phosphonobutane-1,2,4-tricarboxylic acid, acinotrimethylenephosphonic acid, and water-soluble ones thereof. The inhibitor according to claim 1, which is at least one selected from the group consisting of salts. 3.Water-soluble organic phosphonic acids are 1-hydroxyethylidene-1,1-diphosphonic acid and the following general formula: ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R is H, CH_3, or CH_2-CH_2
The inhibitor according to claim 1, which is a mixture with at least one phosphonocarboxylic acid represented by -COOH. 4. The polymer has the following formula: ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (In the formula, R_1 and R_2 each independently represent hydrogen or a methyl group, and cannot be a methyl group at the same time, and R_
3 is represented by the following formula: ▲There are mathematical formulas, chemical formulas, tables, etc.▼ In the formula, X_1 and X_2 each independently represent hydrogen, a hydroxyl group, or a methyl group, and n represents an integer from 1 to 3. ) A monoethylenically unsaturated sulfonic acid monomer represented by acrylamide, maleic acid (including maleic anhydride) or the following formula: (wherein, R_1 and R_2 each independently represent hydrogen or a methyl group, and at the same time 1) is a copolymer with at least one monomer selected from monoethylenically unsaturated carboxylic acid monomers represented by Inhibitor. 5. The total amount of monoethylenically unsaturated sulfonic acid monomers in the copolymer is 10 to 90% based on the copolymer.
and the total amount of acrylamide, maleic acid (including maleic anhydride) or monoethylenically unsaturated carboxylic acid monomer is 90 to 10%, Claim 4
Inhibitors listed in section. 6. The molecular weight of the polymer is 1,000 as a weight average molecular weight.
Claim 1 ranging from 100,000 to 100,000
The inhibitor according to any one of Items 1 and 4. 7. The inhibitor according to claim 1, wherein the water-soluble zinc salt is at least one zinc compound selected from the group consisting of zinc chloride, zinc sulfate, zinc acetate, zinc malate, and zinc citrate. .