JPS5923885A - Corrosion inhibitor for metal - Google Patents

Abstract

PURPOSE:To obtain a non-polluting corrosion inhibitor contg. no Cr and phosphates, by incorporating a water soluble copolymer having a specific ether unit and unsatd. carboxylic acid (salt) unit in a corrosion inhibitor for metals in contact with aq. systems. CONSTITUTION:A corrosion inhibitor contains a water soluble copolymer having a mono(metha)allyl ether unit (a) of trivalent or higher polyhydric alcohol, an unsatd. carboxylic acid (salt) unit (b), and if necessary, the other unsatd. monomer unit (c). The unit (a) here is the compd. expressed by the formula (R1 is H, CH3, Y1 is the residual group excluding OH from trivalent or higher polyhydric alcohol, P is >=2 integer), or the like. The corrosion inhibitor maintains the initial corrosion inhibiting effect even if the concn. of corrosive ions of soluble salts, more particularly chloride ions, sulfate ions or the like is high or the temp. is high. However, the biological decomposability is smaller as compared to ordinary oxycarboxylic acids, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to corrosion inhibitors for metals. Historically speaking,
Concerning corrosion inhibitors for metals that come into contact with aqueous systems. Conventionally, chromates and various phosphates are well known as corrosion inhibitors used in open and closed cooling water systems. However, because chromate is highly toxic, wastewater regulations are in place, making it practically difficult to use. Furthermore, although phosphates have low toxicity, they cause eutrophication when discharged into the Inn River or the Inland Sea, so their active use is undesirable for environmental reasons.

Therefore, research is being conducted in various fields on corrosion inhibitors that do not contain harmful heavy metals such as chromium and phosphates. Examples of currently known corrosion inhibitor components include oxycarphonic acids such as tartaric acid, citric acid, and gluconic acid. When these oxycarboxylic acids are used alone, they are susceptible to the concentration and temperature of dissolved salts, corrosive ions such as chloride ions and sulfate ions. The higher the value, the lower the corrosion inhibition effect, and it is difficult to apply to a wide range of water systems because it is biodegradable.

As a result of extensive research aimed at making use of the anticorrosive properties of oxycarboxylic acids and improving the corrosion inhibiting effect, Akira Kinie et al. developed the present invention, which does not contain harmful heavy metals such as chlorine and phosphates. We have completed a non-polluting corrosion inhibitor.

That is, the present invention comprises a mono(meth)allyl ether unit (a) of a polyhydric alcohol having a valence of 3 to 42, an unsaturated carboxylic acid (salt) unit (I), and other unsaturated monomers as necessary. This is a metal corrosion inhibitor characterized by containing a water-soluble copolymer (A) having a body unit (C).

The mono(meth)allyl ether of a trihydric or higher polyhydric alcohol forming the unit (+1) of the copolymer (A) in the present invention is as follows.

General formula % Formula % (1) (wherein, R1 is 11 or CD3. Y is a residue of a trihydric or higher polyhydric alcohol, P is an integer of 2 or more, preferably an integer of 2 to 7, especially (preferably an integer of 2 to 3).

The residue of a polyhydric alcohol having a valence of 3 or more means a group obtained by removing a hydroxyl group from a polyhydric alcohol.

Examples of polyhydric alcohols forming residues of trihydric or higher polyhydric alcohols include aliphatic polyhydric alcohols, aliphatic amino polyhydric alcohols, and/or alkylenoxy and do adducts thereof. Examples of aliphatic polyhydric alcohols include aliphatic octahydric alcohols such as glycerin, 1,2,4-
Butanetriol.

1-limethylolethane, 1-limethylolbropano.

1.2.6-hexaztriol, aliphatic tetrahydric alcohols such as pentaerythritol, erythritol,
d- and e-trainode pentahydric alcohols, such as d- and s-arahisoto, atonito, aliphatic hexahydric alcohols, such as (1- and e-trunpi-, d- and l-mannite, and sugars such as d-glucose).

(1-caractose, d-xylose, sucrose,
Examples of aliphatic amine polyhydric alcohols such as lactose and maltose include triethanolamine 7 and mixtures of two or more thereof.

Examples of alkylene oxide adducts include ethylene oxide and/or propylene oxide adducts. The number of moles of alkylene oxide added is usually 1 to 4.
o is preferably 1 to 1o. The number of moles added per O11 is usually 1 to 5, preferably 1 to 3. J: Among the polyhydric alcohols listed above, preferably trihydric alcohol,
Particularly preferred are chrycerin and ]-rimethylolpropane.

As a mono(meth)allyl ether of a polyhydric alcohol with a valence of 3 JJ, p, for example, -F general formula % formula % (2) [In the formula, the ratio 1 is the same as the ratio in the general formula (1); 1 (is CH3 or C)-"I5; A is an alkylene group having 2 to 3 carbon atoms in+nl+12, n3 has a total of 0 or 1 to 5
0 or positive integer i 7n, , m2 is 1 to 4
is an integer of ].

General formulas (2), (3), (4), (5
), those in which J, n2, and r13 are 0 are preferred from the viewpoint of the method for producing the compound.

A specific 1υ compound is 1-(meth)allyloxy-
2,3-dihydroxypropano 12-(meth)allyloxy-1,3-dihydroxypropano; 1-(meth)allyloxy-3,4-dihydroxybutano 11-(meth)allyloxy-2,2-dihydroquinemethyl Propano; 1-(meth)allyloxy-2,2-dihydroquinemethylbutane il (meth)allyloxyethoxy-2
, 3-dihydroquinopropane and l-(meth)allyloxy-2,2,2-trimethylolethane. Preferred among these are 1-(meth)allyloxy-2,3-dihydroxypropane; 2-(meth)allyloxy-1,3-dihydroxypropano and 1-(meth)allyloxy-2,2-dihydroquinemethylbutane. It is. The monomer constituting the unsaturated carboxylic acid (salt) unit is monoethylenically unsaturated polycalepho/
Acid τ (salt) (maleic acid (salt), fumaric acid (salt)
, itaconoic acid (salt), etc.], monoethylenically unsaturated monocalyponic acid (salt) ((meth)acrylic acid (salt))
, chloric acid (salt), cinnamic acid (salt), vinylbenzoic acid (salt), etc.]. Among these, preferred C) are acrylic acid (salt) and especially maleic acid (salt).
salts), I and mixtures of two or more of these.

The unsaturated carboxylic acid (salt) unit (b) may be in the acid form or may be an alkali metal, ammonium or amine salt. As an alkali metal, C is +N+L IK,
Examples include Li. The amine has 1 to 5 carbon atoms.
mono-, di-, and 1-realkylamines having an alkyl group; mono-, di-, and trialkanolaminos such as triethanolamine; and heterocyclic amines such as birin.

Among the unsaturated carboxylic acids (salts), those are preferred, and the other unsaturated monomer (C) used can be arbitrarily selected as long as the copolymer pores maintain water solubility. Examples of this unsaturated monomer include the following.

(1) Hydrophilic unsaturated monomer ■) Monoethylenically unsaturated sulfonic acid monomer: aliphatic or aromatic monoethylenically unsaturated monomer/phonic acids such as vinyl sulfonic acid; styrene sulfonic acid; ) Allylsulfone N ((meth)allylsulfonic acid, 2
-Hydroxy-3-(meth)allyloxypropanosulfonic acid]; (meth)acrylicsulfonic acids [starefoprovir (meth)acrylate, 2-hydroxy-3-
(meth)acryloxypropylsulfonic acid, 2. -(meth)acryloylamino-2,2-dimethylethanosulfonic acid'-);
Recali metal salts, ammonium salts, amine salts, etc. 2) Monoethylenically unsaturated alcohols: (meth)allyl alcohol, etc. 3) Polyols of monoethylenically unsaturated mono- or polycarboxylic acids (alkylenoglycols, glycerin,
(Polyoxyalkylenoglycol, etc.) Ester: Hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate-1-, h-ethylenoglycol (meth)acrylate, etc. (2) Weakly hydrophilic to hydrophobic monomers 1) Alkyl esters of monoethylenically unsaturated freho/acids: methyl (meth)acrylate-1-, ethyl (meth)acrylate, maleic acid diethyl ester.

2-Ethylhexol (meth)acrylate-1-, l-tenyl (meth)acrylate-1-, stearyl (ivy)acrylate-1-nato2) Monoethylenoid infl+amidoni(meth)acrylamide; N-alkyl (meth) Acrylamides such as N-methylacrylamide, N-hydroxyalkyl (meth)acrylamide, N,N-dihydroxyalkyl (meth)acrylamide, etc. 3) Esters of monoethylenically unsaturated and saturated atrecols: vinyl acetate, probionoic acid, acetic acid c) Allyl, etc. 4) Monoethylenically unsaturated nido! (meth)acrylonitrile, etc. 5) Aromatic monoethylenically unsaturated nide bodies: styrene, alkylstyrene, hazymedelstyrene, etc. 6) Monoethylenically unsaturated ether monomers: vinyl ethyl ether, hinilph 'Robyl edel avinyl isobutyl ether, Ari I leethyl ether, etc. (3) Geno-containing body: Preferable among these other unsaturated monomers such as chloride, vinylithia chloride, etc. The ones are vinyl sulfonic acid and styrenosulfonoic acid.

(meth)allyl alcohol, (meth)acrylamide,
These include hinyl acetate, styrene, hinyl chloride, and mixtures of two or more of these.

Unit (・l) in the water bathable copolymer (A) in the present invention
Considering the corrosion inhibiting effect, the molar ratio of units () and ()) is usually (a): (b) = 1: 0.
3 to 1:10.

” - At the molar ratio, if (b) is less than 03, then l
) remains in the system, making it difficult to copolymerize completely.If (1)) exceeds 10, the effect of the hydroxyl groups in the resulting water-soluble copolymer (i) decreases, resulting in a sufficient corrosion inhibiting effect. I can't get it. When (b) is an unsaturated monocarboxylic acid (salt), preferably (a): (b) = 1: 0.8~
In case of unsaturated polycarboxylic acid (salt) or unsaturated polycarboxylic acid (salt), the equivalent amount of carboquino-I group per mole is more than twice that of unsaturated mono-JI leponic acid (salt). Therefore, the ratio is preferably (+L): (+1) -1:04 to 1:4. Also, the sum of (+l) and mountain) in (A) is (/1
) is usually 50% or more, or 65% or more, based on the weight of the material. The sum of (+1) and (1]) or 5
If 0% rice is used, the effect of the hydroxyl group of the water-centered copolymer (A) is reduced, and a sufficient corrosion-inhibiting effect cannot be obtained. The amount of units (C) is not particularly limited as long as the copolymer shows water solubility, but it is usually 50% or more and preferably 35% or less based on the weight of the water-soluble copolymer (A) ((C) Usually 80% if the amount is around 7g of weakly hydrophilic or hydrophobic monomers.
The amount below is preferably 2% or less. (C)
If the amount is more than L, the effect of the resulting water-soluble copolymer (A) decreases, and a 1-minute corrosion inhibiting effect cannot be obtained.The water-soluble copolymer (A) in the present invention is trivalent or more It can be produced by copolymerizing a mono(meth)allyl ether of a polyhydric alcohol, an unsaturated carboxylic acid, and, if necessary, other unsaturated monomers in a water bath liquid. A specific method for producing such a copolymer is described in Japanese Patent Application No. 57-4868.
Examples include the method described in the specification (in the case of maleino acid) and the method using another unsaturated carboxylic acid in place of maleino acid in this method.

In addition, the water-soluble copolymer (A) is produced by copolymerizing their precursors [monomers that can become (a) or (b) by hydrolysis] instead of copolymerizing the middle weights listed in 1-1. It can also be produced by hydrolysis. For example, instead of an unsaturated carbonic acid, its lj (g hydrate (maleic anhydride, 71+ (itaconic acid), ester (alkyl ester of monoethylenically unsaturated carboxylic acid mentioned above), etc.), dilyl ( (acrylo-di-I, ryl), amide (acrylamide), etc., and/or its anacur, ester, etc. in place of the mono(meth)allyl ether of polyhydric alcohol-I of 3 or more valences. Copolymerization is carried out, followed by hydrolysis to obtain the kosuri unit (a), (
+1) and optionally (C) copolymer (A)
can be manufactured.

In the method described in L, polyhydric alcohol mono(
Examples of acetals and esters of meth)allyl ethers include general formulas (5) and (6) +3yohi(?
) can be used.

co2= 6- cJ■2o6y2Mox1) p2
...(6) Or it is a group excluding all, and 几 is 1
1 or (JA: I3. R' is II, CLI3 or C2■■5. >C-CJ.

1'2 is an integer greater than or equal to 1. In the method described above, polymerization can be carried out by a conventional method (radical polymerization or solution polymerization, etc.), and hydrolysis can also be carried out by a conventional method (7IO thermal F or in the presence of an acid or alkali).

The copolymer in the present invention is a colorless or pale yellow liquid or solid water-soluble polymer, and its molecular weight range is usually 600 to 200,000, preferably 1,50.
0 to 100,000, particularly preferably a, oo.

It is 10,000. If the molecular weight of this copolymer is too low, biodegradability will become significant and the effect of suppressing one side food will decrease.

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 watercolor in the same manner as conventional corrosion inhibitors.

The degree of use of the corrosion inhibitor of the present invention is determined depending on the purpose, but generally the active ingredient is 5 to 50%
0 gate ■ is sufficiently effective. It is not necessary to adjust the pil range of the target water system, but it is generally pH 6 to pJ, J,
13, preferably pH 5-10.

The corrosion inhibitors of the present invention can be used in a wide variety of applications. Target surface 46-2 to which this corrosion inhibitor is applied
No. 170, 4.6-217 January, 49-42477
No. 5], No. 4,1578, No. 52-3383,
il as described in No. 52-15530 etc.
Can be used for J-way.

The corrosion inhibitor of the present invention is sufficiently effective against aqueous systems made of 100% pure metal, but other corrosion inhibitors may be used if necessary, such as when other metals are also used. For example, oxycarboxylic acids, mercap l-hy J
Thiabul such as chiapur, azoles such as benozotriazole, water-soluble amines such as cyclohexylamino, hydrazine alkylamine, polyamine, ethyleneinoimine, pyrrolidino, piperidine, piperazine,
Organic compounds such as imine 7 such as kedimine, hydroxy->tumic acids such as porumhydroxamic acid, acetohydroxamic acid, and benozhydroxamic acid; nitrites, silicates.

Ortho-, k-polymerization-2 various organic phosphates, borates.

In addition, if necessary, conventional micro-dispersants 1, such as acrylic acid homo- and copolymers (/$ (sodium polyacrylate, partial hydrolyzate of polyacrylamide, etc.)) may be used.
, maleinoic acid homo- and copolymers.

b)) Conoacid homo- and copolymers, acrylic acid copolymers containing 2-hydroquine ethyl methacrylic acid The corrosion inhibitor of the present invention has a concentration of dissolved salts, especially corrosive ions such as chloride ions and sulfate ions. And it is not easily affected by temperature, and its corrosion inhibiting effect does not decrease even if the concentration of L-phonocytic ions increases or the temperature increases. Furthermore, it is a corrosion inhibitor that is less biodegradable than ordinary oxycarboxylic acids.

The present invention will be further explained below with reference to Examples and Reference Examples, but the present invention is not limited thereto.

Reference Example 1 Add a stirrer to the fourth flask of 1e, and add the temperature Fig' + drops l1l-1-,! Base gas introduction pipe and reflux condensing pipe attachment, 1-allyloxy-2,3-dihydro-)
[132 g of cypropano, 16 g of maleic acid] and 2 g of water
I prepared 0M. Separately, add 7 monomonium persulfate to the heater.
g was taken, and an aqueous initiator solution which had been added to 60F water and homogeneously decomposed was put into a dropping row 1. After removing oxygen from the system with nitrogen gas, the monomer aqueous solution in the flask was heated to 85°C.
The initiator aqueous solution was added dropwise from the dropping funnel over 30 minutes. Subsequently, the mixture was aged at 90°C for 1 hour to obtain 511 g of a transparent and uniform aqueous solution of the water-soluble copolymer. The solid content of the aqueous solution was 34.8% (W/W), and the molecular weight was GI'
It was 4000 more than C.

The aqueous solution was used as a corrosion inhibitor in Case I of Example 1.

Reference Example 2 150f of toluene was placed in a reaction vessel similar to Reference Example 1 and heated to 80'C. Separately in a beaker, 2-methyl-4-
Allyloxymethyl-1,3-dioxolane '12y and maleic anhydride 98f were taken and heated to 50°C to dissolve them. After cooling to room temperature, benozoyl peroxide 1
1yt=u and uniformly dissolved to prepare a monomer solution.

This monomer solution was added dropwise to the previously prepared toluene for 30 minutes,
Polymerization was continued at 80°C for 1 hour and then at 100°C for 1 hour. After completion of polymerization, cool to 40°C, separate the precipitated copolymer from the toluene solution, and dry under reduced pressure.
Add 300 g of water to 66 g of the copolymer obtained in step t, boil it υ1), and expel the acetaldehyde produced by hydrolysis from the system together with water.
Distilled in time.

After further heating for 2 hours and hydrolysis, 340 g of a transparent and uniform aqueous solution of the water-soluble copolymer was obtained. The solid content of the aqueous solution is 51% UW/W), the molecular weight is (a' from 31'G,
It was ooo.

The aqueous solution was used as a corrosion inhibitor in Case 11 of Example 1.

Reference Example 3 An aqueous solution was obtained in the same manner as in Reference Example 1 except that the raw materials or ratios were changed, and used as a corrosion inhibitor in Cases Ill, IV, and ■ of Example-1.

Reference Example 4 Toluenol 5 II /
1 and heated to 80°C. Separately, take 648 g of 1-allyloxo-2,3-diacetquine propano and 5 g of maleinoic anhydride in a beaker and add to 50"C.
:11! The mixture was poured and dissolved, and 6.2 g of styrene was mixed therein.

After cooling to room temperature, 5 g of benozoyl peroxide was added and uniformly dissolved to prepare a monomer solution. This monomer bath solution was added dropwise to the previously prepared toluene over 45 minutes, and heated to 80°C.
Polymerization was carried out for 1 hour at 100°C and for 2 hours at 100°C. After the polymerization was completed, the copolymer was cooled to 40°C, and the precipitated copolymer was distributed from house to house, followed by drying under reduced pressure to obtain 118 g of copolymer.

Water of 55y was added to the L copolymer and heated under reflux for 3 hours to perform hydrolysis, and the resulting homogeneous aqueous solution was evaporated to dryness to obtain a hydrolyzed copolymer 971V. The hydrolysis rate is 93q6 according to the kenization value, and the molecular weight is 3,5 according to OPC.
00 J] Tsuta.

98f of water was added to the copolymer to give a solids content of 50. . %
(W/W) was prepared as an aqueous solution and used as a corrosion inhibitor in Case ① of Example 1.

A performance test of the agent was conducted.

The test water used was synthesized by adding various ingredients to Yokohama city water, and its water quality is as follows.

pH 7.6 Sleepiness conductivity 240 μS/ctn Total hardness 7.4
II 1J m force l lesium hardness 50ppm
M -7, IL/potassium 54 pl) rn Chloride ion 1.57171 Hl (a, gCaCO3) Sulfate ion 25 ppm Silica 28 yen (
+ixS 102) The following corrosion inhibitors were added to this test water in one 100P well, and after adjusting the pH to 7.0 and the water temperature to 50°C, a rotating disk was immersed at a rotation speed of 160 rpm. death.

This state was maintained for 20 hours.

For the two discs, soft rope (diameter 50M, wall thickness 1 mm, material 5POC) was used.

The corrosion inhibitor used was that obtained in Reference Example 1-4. For comparison, polyacrylic acid sol (molecule 3t, approx. 4,
500), hollyhinyl alcohol (molecular paper approx. 15
,000) was used. The results are shown in Table-1.

From this result, it can be seen that the corrosion inhibitor of the present invention has a far more corrosion inhibiting effect than the agent shown as Comparison 1.

Table 1 Example 2 In order to clarify that the corrosion inhibitor of the present invention has lower biodegradability than existing oxycarboxylic acids etc., the following was carried out. Added 1100pp of B as a corrosion inhibitor to the same test water, and added activated sludge to MLSS.
In addition to the water temperature of 3QIIpm, a 7-day food test was conducted at a water temperature of 30°C.

The test pieces were mild steel round bars (10 rods in diameter).

The change in corrosion rate over time was measured using a commercially available corrosion needle.

As a conventional oxycarboxylic acid corrosion inhibitor.

I chose citric acid.

The results are shown in Table-2.

Table 2 Based on these results, are there two corrosion inhibition effects of the present invention? While RL was able to provide a stable corrosion inhibiting effect over the 1-day period, citric acid was found to have a significantly lower effect from the 2nd day onwards.

Claims (1)

[Scope of Claims] ], a mono(meth)allyl ether unit of a polyhydric alcohol with a valence of -8 or higher, l), an unsaturated carboxylic acid (salt) unit (
b) and, if necessary, other unsaturated monomers (C)? A corrosion inhibitor for metals, comprising a water-soluble copolymer (A) having the following properties. 2, the molar ratio of ()L) and (1)) is (a) two (b
)=1:03 to 1:10, the corrosion inhibitor according to claim 1. 8. Claims where the sum of (a) and (b) is 50% or more based on the weight of (A) @Claim 1 or 2
Corrosion inhibitors as described in section. 4. The molecular weight of the water-soluble copolymer (A) is 500 to 200
．． 000, the corrosion inhibitor according to any one of claims 1 to 3. 5. Addition of water-soluble copolymer) to water is 5 to 50
5. The corrosion inhibitor according to any one of claims 1 to 4, wherein the corrosion inhibitor is 0ppl. 6. The corrosion inhibitor according to any one of claims 1 to 5, wherein the polyhydric alcohol having a valence of 3 or more is an aliphatic triol and/or an alkylene oxide adduct thereof. 7. Aliphatic triol is glycerin, 1,2゜4-butanetriol, 1,2,6-hex→hornotriol,
7. The corrosion inhibitor according to claim 6, which is a compound selected from the group consisting of 1-herimethyloleta/and trimedylolpropane. 8. The corrosion inhibitor according to claim 6 or 7, wherein the alkylenoxide adduct is an ethylene oxide and/or propylene oxide adduct. 9. The corrosion inhibitor according to any one of claims 1 to 8, wherein the unsaturated carboxylic acid is maleinoic acid.