JPS596382A - Corrosion inhibitor for metal - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to corrosion inhibitors for metals, and more particularly to corrosion inhibitors for metals in contact with mineral waters. Acid salts and various phosphates are well known. However, since chromate salts are highly toxic, emission regulations are in place, and phosphate salts are a cause of red tide, so their active use is not desirable from an environmental standpoint.

Furthermore, oxycarboxylic acids such as citric acid and tartaric acid, which are known corrosion inhibitors, are easily decomposed by microorganisms, making it difficult to maintain their corrosion inhibiting effect.

In order to solve these drawbacks of the conventional technology, the present inventors conducted intensive research with the aim of developing a non-polluting corrosion inhibitor that does not contain harmful metals such as chromium and phosphates, and as a result, the present invention was developed. The invention was completed.

That is, the present invention provides polymerization with the general formula % (where AI and A2 each independently represent hydrogen, a methyl group, or -COOXzt", and AI and At do not simultaneously become -C00Xt). , As represents hydrogen, a methyl group or CHz C00X3, and A3 is CHz C
In the case of 00Xs, AI and A2 each independently represent hydrogen or a methyl group, and Xs, Xs, and Xs each independently represent hydrogen, a monovalent metal, a divalent metal, an ammonium group, or an organic amine group. ) At least one monomer of t' (11) selected from the group consisting of compounds giving repeating units represented by r each independently represents 0 or an integer from 1 to 100, and R
, and R2 each independently represent an alkylene group having 2 to 4 carbon atoms; Salts of valent metals, ammonium groups, or organic amine groups, or mono- or diesters of alkyl groups having 1 to 4 carbon atoms), monovalent sulfone groups (however, salts of monovalent metals, ammonium groups, or organic amine groups, or mono- or diesters of alkyl groups having 1 to 4 carbon atoms); salts, or esters of alkyl groups having 1 to 4 carbon atoms), or monovalent sulfate groups (including salts of monovalent metals, divalent metals, ammonium groups, or organic amine groups, or alkyl groups having 1 to 4 carbon atoms); or (2) Y and 2 together represent a hydroxyl group, a divalent phosphoric acid group, a divalent sulfonic acid group, or a divalent sulfuric acid group. ) at least one selected from the group consisting of compounds represented by
Species allyl ether monomers (Ill, and monomers copolymerizable with these monomers (Ml), monomer (It, 20 to 99.5 mol, monomer (n) o
, s~80 mol% and monomer (Ill 0~40 mol% (excluding 1), total of (Ill and (1) 11
00 morti. ) is a copolymer (Alt-based metal corrosion inhibitor).

Examples of the monomer (1) used in the present invention include (meth)acrylic acid (acrylic acid represents methacrylic acid. The same applies hereinafter), maleic acid, fumarusaka itaconic acid, and/or L salts thereof. (eg, sodium salts, lithium salts, potassium salts, ammonium salts, etc.). Of course, maleic anhydride or itaconic anhydride can be used as a monomer providing this repeating unit.

Examples of the monomer (n) include 3-allyloxypropane-1,2-diol, 3-allyloxypropane-1,2
-Diol, sulfonate, 3-aryloxy 1.2-
Di(poly)oxyethylene ether propane, 3-allyloxy-1,2-di(poly)oxyethylene ether propane sulfonate, 3-allyloxy-1,2-cy(poly)oxypropylene ether propane, 3-allyloxy-1,
2-di(poly)oxypropylene ether propane sulfonate, 6-arylokydihexane-1.2.3.4.
5-pentaol, 6-arylokydihexane-1.2.
3.4.5-pentaol sulfonate, 6-allyloxy-1,2,3,4,5-penta(poly)oxyethyleneetherhexane, 6-allyloxy-1,λ3.4°5-penta(poly)oxy It can be diluted with propylene ether hexane and the like.

Monomers (Ml include styrene, vinyl acetate, (meth)acrylonitrile, (meth)acrylamide, methyl (meth)acrylate, ethyl (meth)acrylate,
Butyl (meth)acrylate, 2-ethylhexyl methacrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, etc.
=6 can be added.

The composition ratio of monomer (11, monomer (Ill) and monomer (Ill) in copolymer (4) is monomer (1120-99
．． 5 mol, monomer (Illo, s ~ 80 mol,
and monomer (1) 0 to 40 mol% ((11(loss(■
) is 100 molti).

If any of the monomers (11, (■) and (l) deviates from the above range, the excellent corrosion inhibiting effect of the present invention cannot be obtained.

The copolymer (2) of the present invention can be polymerized by a conventionally known method. For example, polymerization can be carried out in water, an organic solvent, or a mixed solvent of a water-soluble solvent and water. At this time, for polymerization in an aqueous medium, persulfate, hydrogen peroxide, etc. are used as a polymerization initiator, and arR hydrogen is used as a polymerization initiator.
Accelerators such as IJum and ascorbic acid can be used in combination. For polymerization in an organic solvent, an azo compound, an organic peroxide, or the like is used as a polymerization initiator, and an accelerator such as an amine compound can be used in combination. For polymerization in a mixed solvent of a water-soluble organic solvent and water, an appropriate polymerization initiator or a combination of a polymerization initiator and an accelerator can be selected from among the various polymerization initiators described above.

The thus obtained copolymer (Al) can be used as a corrosion inhibitor as it is, but if necessary, it can be further neutralized with an alkaline substance (or a trace of hydration) before use. Examples include hydroxides, chlorides and carbonates of monovalent and divalent metals; ammonia; organic amines and the like.

In addition, the molecular weight of this copolymer is 1,200,000 or less.
More preferably, it is about 500 to 50,000.

The corrosion inhibitor of the present invention contains the above-mentioned copolymer as an active ingredient, and is used by being directly added to the target water system in the same way as conventional corrosion inhibitors.

The corrosion inhibitor of the present invention can be applied to all types of water such as pure water, soft water, tap water, and industrial water, and the concentration used is determined depending on the purpose, but generally the active ingredient is 5 to 500μ. is sufficiently effective. Also, the pH of the target water system
There is no need to adjust the range, but generally hpH6~
13, preferably pH 6-1O. The target water system to which this corrosion inhibitor is applied may be any water system in which corrosion is a problem, but preferable examples include open circulation, overflow or closed circulation cooling water systems, and prine water systems. In a cooling water system using water or soft water, there are few dissolved salts, which has a positive effect on the corrosion inhibiting effect of the present invention, and is preferable because it exhibits an excellent corrosion inhibiting effect compared to conventional corrosion inhibitors.

The copolymer of the present invention is sufficiently effective against aqueous systems made of steel even when used alone, but if necessary, such as when other metals are also used, other corrosion inhibitors may be added. Oxycarboxylic acids, thiazoles such as mercaptobenzothiazole, azoles such as benzotriazole and tolyltriazole, water-soluble amines such as cyclohexylamine, hydrazines, alkylamines, alkanolamines, and polyamines, ethyleneimine, pyrrolidine, piperidine, and ketimine. imines such as formhydroxamic acid, hydroxamic acids such as benzhydroxamic acid, long chain aliphatic carboxylic acids such as oleic acid, aromatic carboxylic acids such as benzoic acid and phthalic acid, catechol, tannin, lignin, phosphonic acids, etc. It can also be used in combination with inorganic compounds such as organic compounds, nitrites, silicates, various phosphates, borates, zinc salts, nickel salts, aluminum compounds, molybdates, tungstates, etc.
The present invention will be further explained below with reference to Examples, but the present invention is not limited thereto.

Example 1 Test liquids 11 of each water quality shown in Table-■ were placed in a beaker, a predetermined amount of the corrosion inhibitor of the present invention was added thereto, and the water temperature was set to 150C.
was held at A mild steel test piece was suspended from a stirring rod in this beaker and rotated at a rotation speed of 160 rpm.
It remained in that state for days.

The corrosion inhibitors used are shown below.

A, acrylic acid-3-allyloxypropane-1,2-diol (CHz=CHCut OCHz CHCHz
OH)H Na salt of copolymer (molar ratio 4:1 average molecular weight approximately 4,500) B, same as above (molar ratio 19:1 average molecular weight approximately 4,000) C, acrylic acid-3-allyloxypropane-1 , 2-diolsulfonic acid soda (CHz=CHCHz 0-CHz CH-CH2-
Copolymer of 0-8OsNa) (molar ratio 19:1, average molecular weight approximately 400) D, same as above (molar ratio 17:3, average molecular weight approximately 5,000) E
, Na salt of maleic acid-acrylic acid-3-allyloxyfuropane-1,2-diol copolymer (mole ratio 5:3:2 average molecular weight approximately 3,000)F
, malein 1ll-3-allyloxypropane-1,2-
Na salt of diol copolymer (mole ratio 1:1 average molecular weight about 3,500) G, acrylic acid-3-allyloxypropane-1,2-diol sodium salt copolymer (mole ratio 4:l average molecular weight (approximately 3,000) H, Na salt of acrylic acid-3-allyloxypropane-1,2-diol-acrylamide copolymer (molar ratio 15:1:4 average molecular weight approximately 3,500),
As a comparative example, a, sodium polyacrylate (average molecular weight approximately 4.5
GO) b, maleic acid-acrylic acid copolymer (Na
Salt) (molar ratio 1:1, average molecular weight approximately 4.000) was also tested.

The results are shown in Table-2.

In addition, in Table ■, the water quality of 1 corresponds to a closed cooling water system, a low concentration open cooling water system, and a vortex type cooling water system, and the water quality of 2 corresponds to an open cooling water system that is about 3 times more concentrated.Table 1 Table 2 From this result, It can be seen that the corrosion inhibitor of the present invention has a far more corrosion inhibiting effect than the chemicals shown for comparison.

Example 2 A corrosion test was conducted on a gold coin under the same conditions as in Example 1 except that a pure water sound having a conductivity of 1 μs/cm or less was used.

The results are shown in Table-3.

Table 3) From these results, it can be seen that the corrosion inhibitor of the present invention exhibits superior corrosion prevention effects compared to conventional corrosion inhibitors even in pure water systems with extremely low salt concentrations.

Patent applicant Kurita Industries Co., Ltd.

Claims (1)

[Claims] (1) When polymerized, the general formula % formula % (However, in the formula %! and AX each independently represent hydrogen, a methyl group, or 1000Xxt, and AI and 1 simultaneously become 1000X* N represents hydrogen, a methyl group, or CH2C00Xj, and A3 is -C
In the case of Hz-C00Xs, A1 and A2 each independently represent hydrogen or a methyl group, and xl, xl, and X3 each independently represent hydrogen, a monovalent metal, a divalent metal, an ammonium group, or an organic amine group. ) At least one monomer (11) selected from the group consisting of compounds that give a repeating unit represented by each independently represents 0 or an integer from 1 to 100, and R
1 and h independently represent an alkylene group having 2 to 4 carbon atoms, and Y and 2 each independently represent a hydroxyl group, an alkoxy group having 1 to 4 carbon atoms, a monovalent phosphate group (but Monovalent metals, divalent metals, ammonium groups, < includes salts of organic amine groups, or mono- or diesters of alkyl groups having 1 to 4 carbon atoms), monovalent sulfone groups (however, monovalent metals, divalent salts of metals, ammonium groups, or organic amine groups, or esters of terkyl groups having 1 to 4 carbon atoms), or monovalent sulfate groups (however, monovalent metals, divalent metals, ammonium groups, or organic amine groups) salt, or an ester group of an alkyl group having 1 to 4 carbon atoms) 11-, or ■Y and 2 together represent a hydroxyl group, a divalent phosphate group, a divalent sulfone group, or a divalent sulfate group represents. ) At least 4 species of allyl ether monomers (Ill, and a monomer copolymerizable with these monomers 1) selected from the group consisting of the compounds represented by 1120-995 molti, monomer (1) o, s-80
Molar ratio and monomer (1) 0 to 40 mol% (+1
) Jllll and (1) totaling 100 moles. A copolymer (Alt-based metal corrosion inhibitor) derived using a ratio of