CN1033178C - Corrosion inhibitor for metal - Google Patents

Abstract

To obtain an anticorrosive causing no environmental pollution by using an acrylic copolymer consisting essentially of (meth)acrylic acid and/or a salt thereof and sulfoethyl (meth)acrylate and/or a salt thereof and polymaleic acid and/or a salt thereof as effective components. This anticorrosive for metals contains an acrylic copolymer consisting essentially of (meth)acrylic acid and/or a salt thereof and sulfoethyl (meth)acrylate and/or a salt thereof in 95:5-40:60 ratio and polymaleic acid and/or a salt thereof as effective components. The mol.wt. of the acrylic copolymer is 500-2,000 and that of the polymaleic acid or a salt thereof is 300-5,000.

Description

The anti-corrosion method of ferrous metal in the water system

The invention relates to the method for metal corrosion protection.In more detail, be about under metal and corrosive environment that water contacts, in water, add the metal anti-corrosion method of particular chemical medicament.

At so-called water initiating device, as, in steam-generating installation, heating system, chemical reaction equipment, the cooling water system, corrosive nature when contacting with water, takes place in metal (iron, soft steel, cast iron etc.) easily that constitute this type of device.One to since, in order to prevent this corrosion, advise always and adopt all inhibitors.Wherein, particularly join inorganic salt such as the chromic salt that uses as water-soluble inhibitor in the recirculated waters such as water coolant, phosphoric acid salt, nitrite and thanomin etc., particularly well-known.

But the past is considered to the chromic acid compounds such as potassium bichromate of excellent inhibitor always, but re-uses hardly because of it has toxicity now.And things such as other Tripyrophosphoric acid also because the regulation of public hazards aspect, and limit its use gradually.In addition, also have the material of picture nitrite and low-grade amine and so on,, when using them, also can be subjected to all restrictions in case generate carcinogenic nitrosamine person simultaneously and with reacting.

The objective of the invention is to develop, do not use heavy metal compound, nitrogen compound, the phosphorus compound that can cause public hazards, and can bring into play the anti-corrosion method of good corrosion protection result.

Some multipolymer in the used acrylic copolymer among the present invention, past has found to have the fouling of preventing effect in water system, this is well-known, and (Japan, spy open clear 60-41595 communique (promptly " openly speciallyying permit communique " 1985 No. 41595)., this kind multipolymer has the discovery of corrosion protection effect to metal, but is strange.Particularly, prevent that fouling is based on the sequestering action of compound used therefor, thereby suppress the separating out of hardness components (especially calcium component) in the water, the corrosion protection effect of so-called metallic surface then is based on the heterogenetic effect.Therefore, these prevent between the effect of fouling and the corrosion protection effect and first dependency, and also do not have migrating property easily between them in principle.

The present inventor is through studying intensively, and the result is surprised to find that these acrylic copolymers have very excellent corrosion protection effect.

And, also further examination with this acrylic copolymer and other various medicaments simultaneously and usefulness, the result found again, by it and polymaleic acid class and usefulness, can obtain the fact of more excellent synergy corrosion protection effect.

Therefore the present invention can provide a kind of method of metal corrosion protection, it is characterized in that in the water system of corrosion protection object:

Be added into the acrylic copolymer (i) that constitutes as the principal monomer composition with (methyl) vinylformic acid and/or its salt (A) and (methyl) vinylformic acid sulfo-ethyl ester and/or its salt (B), with this corrosion inhibitor for metal of forming as effective constituent; And contain the corrosion inhibitor for metal of (ii) forming with this acrylic copolymer (i) and polymaleic acid and/or its salt as effective constituent.

In the used acryllic acid based copolymer of the present invention,, can recommend to adopt: vinylformic acid, methacrylic acid and these sour an alkali metal salts etc. as its (methyl) vinylformic acid and/or its salt (A) person who forms unit.

And form in (methyl) vinylformic acid sulfo-ethyl ester and/or its salt (B) of unit as another, can recommend: their sulfo-ethyl ester and an alkali metal salts of these esters etc. separately of vinylformic acid, methacrylic acid.

Above-mentioned multipolymer is made of as main component monomer (A) and monomer (B), and monomer (A) and (B) with 95: 5 to 40: 60 mol ratio and constitutor is better, then better by 90: 10 to 50: 50 constitutors of mol ratio on the corrosion protection effect.

In addition, the molecular weight of above-mentioned multipolymer, being adjusted into about 500-20,000, its corrosion protection effect is good, and is about 1,000-10,000 is then better.

Above-mentioned multipolymer can be made every effort to overcome (ア Network ア リ Star Network) person (registered trademark, Nippon Shokubai Kagaku Kogyo Co., Ltd) by commodity A Kua by name and be obtained, and as for the preparation aspect of the used inhibitor of the present invention, also is to adopt this commercially available product comparatively easy.But, re-use after also can producing this multipolymer.

In this case,, be prepared by various polymerizations though can adopt common polymerization starter, yet, be easy to the control aspect from reaction and consider that polymerization is better in solvent.

As used in this case solvent, though can select all kinds of SOLVENTS, during from above-mentioned monomer (A) and the consideration of solvability (B), then comparatively suitable with water, lower alcohol.

And, need according to above-mentioned solvent types and selective polymerization initiator suitably.For example, in water solvent, can adopt an alkali metal salt or its ammonium salt of persulfuric acid, perhaps hydrogen peroxide etc.And in the lower alcohol equal solvent time, then can recommend benzoyl peroxide, lauroyl peroxide, hydrogen phosphide cumene, Diisopropyl azodicarboxylate etc.

In above-mentioned polyreaction, also can suitably select suitable promotor or chain-transfer agent also to use together.

The temperature of above-mentioned polyreaction can suitably be determined according to condition such as solvent for use and polymerization starter, but normally react in 0-120 ℃ of scope.

As the polymaleic acid among the present invention, though various molecular weights all can be used, consider from being easy to synthetic aspect, then be advisable with the molecular weight junior, can fit for service be that molecular weight is about 300-5000 person generally.And consider from the corrosion protection effect, then molecular weight less than 1000 for good especially.These polymaleic aciies can obtain by following method, for example, in organic solvent, employing is greater than 5% polymerization starter (benzoyl peroxide, Diisopropyl azodicarboxylate etc.), make Maleic Acid, Anhydrous aggregate into poly-Maleic Acid, Anhydrous under with polymerizing condition such as heat additional, then, among water etc., add moisture be situated between it and obtain; Perhaps, in the aqueous solution, toxilic acid or Maleic Acid, Anhydrous are made single alkali metal salts or ammonium salt, adopt polymerization starter (hydrogen peroxide class, dialkyl group peroxide and persulfuric acid salt etc.), additionally wait polymerizing condition acquisition down to heat.And, as polymaleic acid salt, in fact so long as water-soluble person just can use, for example, what can be suitable for using has, the salt that low-grade alkylamine such as an alkali metal salt of lithium, sodium and sylvite and so on, ammonium salt or it and methylamine, dimethylamine, Trimethylamine 99, ethamine, diethylamine, propylamine is combined to.In the middle of these,, use an alkali metal salt for well from the corrosion protection effect.Again, the part ester body of polymaleic acid, or part amine body all can be used as polymkeric substance, promptly can use as long as come down to water-soluble person.

In addition, polymaleic acid class one is to as scale inhibitor (Japan, special public clear 53-20475 communique (i.e. " special permission communique " 1978 No. 20475)) be well-known.And, with specific corrosion compound and time spent, it also is known (spy of Japan opens clear 53-149837 communique (promptly " openly speciallyying permit communique " 1978 No. 149837), and the spy opens clear 53-149836 communique (promptly " openly speciallyying permit communique " 1978 No. 149836)) as the ancillary component role of corrosion protection.But finding also has the document of abundant corrosion protection effect but not have when itself uses separately.

The aforementioned inhibitor of using as the present invention of effective constituent with acrylic copolymer, the aqueous solution that can be made into 5-50% (weight) is usually used.And in the object water of need corrosion protection, add aforesaid propylene acid based copolymer, to make its content in water be 1-500ppm for well.If, just can not perform to the corrosion protection effect of expection less than prescribing a time limit under this scope.And can not obtain higher effect in limited time greater than last, the result causes waste, and is bad on the contrary.And in above-mentioned scope, the addition preferably of corrosion protection effect is 20-200ppm as bringing into play fully.

On the other hand, be the inhibitor of effective constituent with above-mentioned acrylic copolymer and polymaleic acid class, the form that generally also can be dissolved in the water and using.At this moment, concerning 1 parts by weight of acrylic multipolymer, polymaleic acid and/or its salt can be decided to be the 0.1-10 weight part, and from the performance synergistic effect, this is suitable.And it is better with the 0.2-5 weight part.Especially good when being decided to be about 1 weight part.And when adding this kind inhibitor in object water, in two kinds of effective constituents, acrylic copolymer content is 1-500ppm for well.Again, in this scope, can further bring into play more abundant corrosion protection effect, addition is 10-100ppm preferably.

Contain the acrylic copolymer inhibitor this, and the inhibitor that contains acrylic copolymer and polymaleic acid class, join in the corrosion protection object water, just can suppress significantly by this or anti-sealing in the corrosion of the metal, particularly ferrous metal that exist.

In addition, also can in the used inhibitor of the present invention, mix, also can suitably add additives such as other dispersion agent, sterilization and sterilant not hinder other anticorrosive composition of its corrosion protection effect.

The present invention can be described in detail by following embodiment, but the present invention can not be limited in view of the above.

The synthetic example of acrylic copolymer:

In the glass reactor that is equipped with thermometer, agitator, dropping funnel, airway and reflux condensing tube, 89.9 parts in the water of packing into the air in the nitrogen replacement reactor, is heated to 95 ℃ under whipped state.Then, 55.8 parts of monomer mixture solutions of being formed of sodium-salt aqueous solution by 94.3 parts of 40% methacrylic acid sodium water solutions and 40% vinylformic acid sulfo-ethyl ester; And 10% 50 parts of ammonium persulfate aqueous solution, with 120 fens clock times, join in the reactor respectively.After having added, add 10 part of 10% ammonium persulfate aqueous solution with 20 fens clock times again.After the monomer interpolation finishes, make temperature remain in boiling point 120 minutes,, obtain multipolymer to finish polyreaction.This multipolymer viscosity is 88 centipoises.In addition, with high-speed liquid chromatography method determining molecular weight, the result is 1100.

Example

Adopt synthetic condensed water as experimental liquid, 1 liter of the experimental liquid that adds the specified amount medicament is equipped with in the test that the corrosion protection effect of soft steel test film is measured, in 1 liter flat bottom beaker.Soft steel test film (commercially available name of an article SPCC is shaped as 30 * 50 * 1 millimeter rectangle sheet) is hung on end with the stirring rod of motor interlock, and be dipped in the experimental liquid.Set up thermostatted, made the liquid temperature remain in 40 ℃, above-mentioned test film is rotated so that 100 rev/mins speed is lasting, carried out five days test with the heating liner plate.After the off-test, take out test film, gravimetry after pickling, washing, drying is by the weight determination MDD (millimeter/decimetre that is reduced ². day), i.e. the corrosion decrement of each day.The water quality of used synthetic condensed water is shown in (table 1).

The water quality of (table 1) synthetic condensed water

The menu bit value

PH - 8.3

Calcium hardness mg/litre 200

M basicity mg/litre 200

P basicity mg/litre 0

Chlorion mg/litre 200

Sulfate ion mg/litre 100

At first, what Fig. 1 represented is, make the mole of sodium acrylate ((A) composition) and vinylformic acid sulfo-ethyl ester ((B) composition) liken many variations to and the multipolymer that is modulated into, and (A Kua makes every effort to overcome (registered trademark to molecular weight about 4000, Nippon Shokubai Kagaku Kogyo Co., Ltd) LS) and molecular weight about 10,000 (A Kua makes every effort to overcome (the same) NS) person, uses this multipolymer, and be the concentration of 40ppm when adding with its solid state component, the result of the MDD of determination test sheet (being the corrosion decrement of every day).

Fig. 2 represents to adopt the molecular weight of multipolymer to be respectively about 1000 (multipolymers that are modulated in the above-mentioned synthetic example), about 4000 (A Kua makes every effort to overcome (the same) LS), about 7000 (A Kua makes every effort to overcome (the same) PS) and about 10,000 (A Kua makes every effort to overcome (the same) NS), and (A) composition in this multipolymer and (B) mol ratio between the composition with (A): (B)=80: 20 (* tagger), 50: 50 (Δ tagger), the multipolymer that is constituted with 30: 70 (* tagger), when the solid state component of this multipolymer added with the concentration of 40ppm, the determination test sheet corroded the result of decrement MDD every day.

Fig. 3 represents, adopt about 4000 (A Kua makes every effort to overcome (the same) LS) of molecular weight of copolymer, and with (A) composition in this multipolymer and (B) mol ratio between composition be, (A): (B)=80: 20 (* tagger), 50: 50 (Δ tagger) and 30: 70 (* tagger) multipolymer of being constituted, when changing the interpolation concentration of this multipolymer, the determination test sheet corrodes the result of decrement MDD every day.

From above result, at first, show that the mol ratio of sodium acrylate (A) and vinylformic acid sulfo-ethyl ester (B) can be brought into play its effective corrosion protection effect with 95: 5 to 40: 60 the multipolymer that scope was constituted by Fig. 1.

Secondly, as shown in Figure 2, the molecular weight of this multipolymer, can be kept effective corrosion protection effect at 000 o'clock at about 1000-10.

And then illustrate by Fig. 3, when using this inhibitor,, when making composition that it exists, just can give full play to its effect in liquid greater than 20ppm if add multipolymer, as if further adding 40ppm to when above, just can bring into play its corrosion protection effect to greatest extent.

Example 2

Adopt the Osaka City water that concentrates 5 times as experimental liquid, the soft steel test film is carried out the determination test of corrosion protection effect.In the beaker of the peaceful end, 1 liter of the experimental liquid of packing into and being added with the specified amount medicament.Soft steel test film (commercially available name of an article spcc is shaped as 30 * 50 * 1 millimeter rectangle thin slice) is hung on stirring rod end with the motor interlock, and be dipped in the experimental liquid.Set up thermostatted, made the liquid temperature remain in 40 ℃ or 50 ℃ with the heating liner plate.Make above-mentioned test film with the lasting rotation of 100 rev/mins speed, tested three days.After the off-test, take out test film, after pickling, washing, drying, gravimetry.By the weight determination MDD (milligram/decimetre that is reduced ². day), i.e. the corrosion decrement of each day.The used water quality that concentrates 5 times Osaka City is shown in (table 2), and MDD result then is shown in (table 3) and (table 4).

Again, (table 3) expression is that 40 ℃ of liquid temperature, difference is added MDD (the per 1 day corrosion decrement) results under the ratio.As acrylic copolymer, adopt by (A) composition sodium acrylate and (B) sale on the market formed of composition vinylformic acid sulfo-ethyl ester (registered trademark A Kua makes every effort to overcome: following multipolymer Nippon Shokubai Kagaku Kogyo Co., Ltd):

Commodity label mol ratio molecular weight

(A): (B) (average viscosity)

KS-20 80∶20 1000

LS-15 85∶15 4000

LS-20 80∶20 4000

LS-30 70∶30 4000

LS-70 30∶70 4000

PS-20 80∶20 7000

NS-20 80∶20 10000

Then adopt various molecular weight as polymaleic acid salt, promptly molecular weight is about the polymkeric substance of 300-400 and about 900.

On the other hand, (table 4) expression is that 50 ℃ of liquid temperature, and various interpolation is about adopting above-mentioned LS-15, LS-20 and LS-30 (molecular weight 4000) result as acrylic copolymer than corroding decrement (MDD) every day under the condition.

The water quality of (table 2) Osaka City water (* 5 times) condensed water

The menu bit value

PH - 8.45

The little Siemens/cm 940 of conductivity

Total hardness CaCO ₃Mg/litre 242.8

Calcium hardness CaCO ₃Mg/litre 197.0

M basicity CaCO ₃Mg/litre 80.5

P basicity CaCO ₃Mg/litre 0

Chlorion Cl mg/litre 97.7

Sulfate ion SO ₄Mg/litre 172.0

Silicon oxide component S iO ₂Mg/litre 33.5

In addition, for the purpose of reference, when the interpolation concentration of embodiment in above-mentioned (table 3) and (table 4) was 25 mg/litre and 50 mg/litre, the relation of adding ratio and corroding decrement (MDD) every day all was illustrated among Fig. 4 and Fig. 5 with the relation of the molecular weight of acrylic copolymer.

From above-mentioned (table 3) and (table 4) and Fig. 4 and Fig. 5 as can be known, by acrylic copolymer and polymaleic acid salt and usefulness, can make and corrode decrement (MDD) every day and significantly reduce when using respectively separately, synergistic effect has been brought into play in this explanation.Especially, the former: the latter=1: 5-5: 1 o'clock (during the former 1 weight part, the latter should be 0.2-5 mutually), this effect is more remarkable.

The present invention's metal anti-corrosion method is based on the effect of specific acrylic acid series copolymer itself, Perhaps based on the synergistic effect between this copolymer and the poly class, thus to iron, mild steel, Cast iron etc. present excellent corrosion protection effect. And, owing to do not need heavy metal compound, phosphatization Compound, aminated compounds etc., and have the advantage that can use safely.

Fig. 1 is the copolymerization ratio difference of expression along with the acrylic copolymer of main component in the used inhibitor of the present invention, the graphic representation that its corrosion protection effect also changes thereupon.Fig. 2 is the difference of expression along with the acrylic copolymer molecular weight of main component in the used inhibitor of the present invention, the curve that its corrosion protection effect is also different.Fig. 3 is the difference of expression along with the used inhibitor of the present invention addition in the aqueous solution, the graphic representation that its corrosion protection result is also different.Fig. 4 and Fig. 5 are expressions because of acrylic copolymer and Malaysia acids and with the graphic representation that presents different efficacies.

(table 3) result of the test (40 ℃ of liquid temperatures)

(table 3) result of the test (40 ℃ of liquid temperatures) (continuing)

(table 4) result of the test (50 ℃ of liquid temperatures) (continuing)

(table 4) result of the test (50 ℃ of liquid temperatures) (continuing)

Claims (6)

1. the method for the ferrous metal corrosion protection in the water system, it is characterized in that, in the water system of corrosion protection object, interpolation is with (methyl) vinylformic acid and/or its salt (A), and the acrylic copolymer (i) that constitutes as the principal monomer composition of (methyl) vinylformic acid sulfo-ethyl ester and/or its salt (B), its addition is 1-500ppm.

2. the method for the ferrous metal corrosion protection in the water system, it is characterized in that, in the water system of corrosion protection object, add described acrylic copolymer of claim 1 (i) and polymaleic acid and/or its salt (ii), and the addition of acrylic copolymer (i) is 1-500ppm, and acrylic copolymer (i) is 1 with polymaleic acid and/or its salt weight part ratio (ii): 0.1-10.

3. according to the ferrous metal anti-corrosion method in the described water system of claim 1, wherein, in the described acrylic copolymer, composition (A) is 95 with the copolymerization ratio of composition (B): 5-40: 60.

4. according to the metal anti-corrosion method of iron class in the described water system of claim 1, wherein, the molecular weight of described acrylic copolymer is about 500-20000.

5. according to the metal anti-corrosion method of the iron class in the described water system of claim 1, wherein, the molecular weight of described polymaleic acid or its salt is about 300-5000.

6. according to the ferrous metal anti-corrosion method in the described water system of claim 2, wherein, described acrylic copolymer (i) is 1 with polymaleic acid and/or its salt weight part ratio (ii): 0.2-5.

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