JPH01172466A - Anticorrosive paint composition - 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 FIELD OF INDUSTRIAL APPLICATION The present invention relates to an anticorrosive coating composition, and more particularly to a coating that inhibits corrosion of steel in corrosive environments above 80'0 containing hydrogen sulfide, oxygen and water. The present invention relates to an anticorrosive coating composition.

The anticorrosive coating composition of the present invention is used to coat steel materials used in chemical plants or tanks that handle hydrogen sulfide or in which hydrogen sulfide is mixed as an impurity, or in pipelines and stations for transporting natural gas, oil, etc., in which hydrogen sulfide is mixed. It can be suitably used for.

BACKGROUND OF THE INVENTION It is known that hydrogen sulfide (Has) is highly reactive and easily forms sulfides, especially with various metals. Particularly in steel materials, due to the unique reactivity of hydrogen sulfide, so-called hydrogen sulfide cracking occurs, which deteriorates the strength of steel materials, unlike corrosion of general metals, and many accidents have been reported.

Regarding the causes of these hydrogen sulfide cracks, see Nishimura, Kurisu, and Okama, "Journal of the Welding Society J 32(8), 478-4.
89 (1983), hydrogen sulfide cracking is basically the same as hydrogen embrittlement, and hydrogen sulfide forms sulfides on the steel surface and acts as a promoter of hydrogen absorption in the steel material.

In addition, cathodic protection is ineffective as a method of preventing hydrogen sulfide cracking and may cause embrittlement and softening of the paint film.
It is stated that it is relatively effective if an appropriate one is selected. Therefore, a coating material for preventing hydrogen sulfide cracking must first have the ability to control the formation of sulfides on the steel surface.

Such anti-corrosion performance is also necessary for coating materials in corrosive environments where the concentration of hydrogen sulfide is low and does not lead to hydrogen sulfide cracking. In other words, when hydrogen sulfide passes through the coating along with water and oxygen and generates sulfide on the steel surface, the bond between the coating material and the steel material is broken, and as a result, the coating material peels off from the steel surface. However, the anti-corrosion mechanism is lost.

Conventional hydrogen sulfide-resistant anticorrosive paint compositions include, for example, as shown in Japanese Patent Application Laid-Open No. 81-162584, which is effective against corrosion of steel materials in a corrosive environment containing hydrogen sulfide, oxygen, and water at room temperature to around 30°C. As an anticorrosive coating composition that can be used as a coating material that suppresses (II) Consisting of an aliphatic diamine and a polyamide amine consisting of a dimer acid, the ratio of the epoxy resin to the polyamide amine is 0.8/1 to 0.8/1 in terms of reaction equivalent.
100 parts by weight of a 1.4/1 vehicle, 50 to 200 parts by weight of a filler inert to hydrogen sulfide and a water soluble content of 0.
Rust preventive pigment 3 with a pH of 6.0 to 7.0 in dissolved water at 3% or less
There is an anticorrosive coating composition consisting of ~40 parts by weight.

Problems to be Solved by the Invention However, it is difficult to maintain adhesion over a long period of time in a corrosive environment containing hydrogen sulfide, oxygen, and water at temperatures exceeding 60°C. There is a desire to develop an anticorrosive coating composition with excellent long-term adhesion (hereinafter referred to as hydrogen sulfide resistance).

Means for Solving the Problems The present inventors have developed a conventional hydrogen sulfide-resistant anticorrosive paint composition, that is, the anticorrosion paint composition described in JP-A-81-1625134 containing hydrogen sulfide at a temperature exceeding 60°C. The present invention was completed as a result of extensive research into improving hydrogen sulfide resistance in corrosive environments.

That is, in the present invention, the epoxy equivalent obtained by the addition reaction of bisphenol A having 1 to 2 oxirane rings per (+) molecule and epihalohydrin is 180 to 2.
500, and a modified polyamine obtained by reacting and adding glycidyl ether at a ratio of 0.2 to 0.8 moles per mole of a condensate of (II)+++-xylene diamine and epichlorohydrin. The ratio of modified aliphatic polyamine is 0.8/1- in terms of reaction equivalent.
100 parts by weight of a 1.4/l vehicle, 50 to 200 parts by weight of a filler inert to hydrogen sulfide and 0 water solubles.
．． This is an anticorrosive paint composition comprising 3 to 40 parts by weight of an anticorrosive pigment having a pH of 8.0 to 7.0 in dissolved water at 3% or less.

The vehicle used in the anticorrosive coating composition of the present invention is an epoxy resin having an epoxy equivalent of 180 to 2,500 and having 1 to 2 oxirane rings per molecule obtained by the addition reaction of bisphenol A and epihalohydrin (7); Amount - Ratio of 114 or 2 or more of butyl glycidyl ether, phenyl glycidyl ether, 0-talesyl glycidyl ether, and ethylhexyl glycidyl ether in a ratio of 0.2 to 0.6 mol per 1 mol of the condensate of xylene diamine and epichlorohydrin. This is a compound obtained by reacting a modified polyamine added by reaction at a reaction equivalent ratio of 0.8/l-1, 4/1.

The above-mentioned epoxy resin usually contains diglycidyl ether of bisphenol A, which has two oxirane rings per molecule, as a main component, and also contains a small amount of monoglycidyl ether of bisphenol A, which has one oxirane ring per molecule. It is an epoxy resin.

For example, "Epicote" (Yuka Shell Evokishi ■)
, “Ebototo” (Tobu Kasei ■), “Araldite” (
Ciba-Geigy) and "Evicron" (Dainippon Ink Chemical Industry Co., Ltd. 1111) are commercially available products. Epoxy equivalent is 180-2500. It is appropriate to use an epoxy resin with a molecular weight of 380 to 3000. For example, if manufactured by Yuka Shell Epoxy Co., Ltd., Epicoat 828 is used with n=0. The average molecular weight is 380 and the epoxy equivalent is 184 to 194,
Epicoat 1001 has n=2.0. The average molecular weight is 900 and the epoxy equivalent is 450-500, and Epicoat 10
04 is n=3.7. The average molecular weight is 1400 and the epoxy equivalent is 900-1000, and Epicoat 1007 has n=
8.8. Average molecular weight 2900 and epoxy equivalent weight 1750
~2!00.

On the other hand, what is a modified polyamine in which glycidyl ether is reacted and added to a condensate of xylene diamine and epichlorohydrin?

An intestine having a molecular structure of n = 1 to 4
Condensate of silane diamine and epichlorohydrin (for example, Gascamin G37B manufactured by Mitsubishi Gas Chemical Co., Ltd.) has the following structure per mole, and R is a butyl group, a phenyl group, or 0-
This is a modified polyamine obtained by addition-reacting glycidyl ether, which is either a cresyl group or an ethylhexyl group, in a ratio of 0.2 to 0.8 moles.

When the R group of the glycidyl ether is other than the above-mentioned groups,
The hydrogen sulfide resistance at temperatures exceeding 80°C is poor and the purpose of the present invention cannot be achieved, and the addition ratio of glycidyl ether is
■-Synthesis of xylene diamine and epichlorohydrin 1
It is desirable that glycidyl ether is in the range of 0.2 to 0.8 mol based on the mole. If this ratio is less than 0.2 mol, the hydrogen sulfide resistance at temperatures exceeding 60°C will decrease, and if the ratio is less than 0.6 mol, If the curing agent is exceeded, the viscosity increases greatly during synthesis and the composite becomes a hard solid, making it difficult to put it to practical use. Methods for producing these curing agents are disclosed in JP-A-59-33321, etc.

The blending ratio of the above-mentioned epoxy resin and modified polyamine is the number of equivalents of epoxy groups/number of equivalents of active hydrogen of modified polyamine=
It must be between 0.8/1 and 1.4/l.

If this ratio is less than 0.8/1, the coating film will be plasticized by the remaining modified polyamine and become too soft, and the remaining unreacted amine groups will easily attract water; Since there are many unreacted epoxy groups, a normal coating film cannot be obtained and hydrogen sulfide resistance deteriorates.

Next, the filler of the coating composition of the present invention will be explained.

Examples of fillers include carbon black.

One or a mixture of two or more fillers that are inert to hydrogen sulfide, such as titanium oxide, aluminum powder, silicon oxide, aluminum oxide, and magnesium oxide, can be used.

In addition, as rust preventives, Ha, Zn, [Er,
Contains a compound mainly composed of one or more oxides of No and M as an essential component.

Both these fillers and anti-corrosion pigments have a small glacial melt content and are 0.
．． The common property is that it is 3% or less and relatively stable against hydrogen sulfide, which is the original purpose. Here, the pH of the aqueous content and dissolved water was measured at -510122 for the aqueous content and -510124 for the pH of the JIS-.

The purpose of the filler is to provide color and to strengthen the coating, and it must improve the corrosion resistance against general corrosion caused by water and oxygen, or in an environment where hydrogen sulfide is present.

Hunke J, O, C, C, A, vol. 50, 942
On page (19B?), wood is mentioned as a corrosion factor,
The mechanism of permeation through the film is explained; in each case, permeation occurs due to water attacking the interface between the vehicle and the filler pigment.

In the present invention, the interaction between the vehicle and these fillers or antirust pigments at the interface is strong, and water, oxygen, or hydrogen sulfide is difficult to attack and accumulate at this interface. It is. Especially for water, the aqueous solubility is small, and for hydrogen sulfide, H
We considered that the essential condition for not weakening the interaction at this interface is to cause as little reaction as possible with 7S.

Coatings using fillers or anti-corrosion pigments with low aqueous solution content and low reactivity with hydrogen sulfide have excellent performance in standard anti-corrosion tests, such as smooth spray resistance, water resistance and salt water resistance. In addition, it also shows very excellent performance when immersed in hydrogen sulfide water at temperatures exceeding 60°C.

Additionally, if water or hydrogen sulfide attacks the pigment surface, dissolves the pigment, and causes a reaction with hydrogen sulfide, water or hydrogen sulfide tends to accumulate at the interface with the vehicle. This promotes the supply of water or hydrogen sulfide, which is a corrosive factor, to the surface of the steel material, leading to a significant deterioration in anticorrosion performance. In other words, there is little water soluble content,
In addition, a @ film that uses pigments and fillers that have low reactivity with hydrogen sulfide can maintain anticorrosion performance.

Specific examples of such fillers include carbon black, titanium oxide, aluminum powder, silicon oxide, aluminum oxide, elemental magnesium oxide, and Mg called talc.
O* 5i02・M, 03. Al2O called clay
3 fists 5i02, mica theal 2011M, 03.5i0
Compounds such as No. 2 can be mentioned, but other fillers can also be used if they can be used as described above.

On the other hand, anticorrosion pigments are generally metal salts that have a high aqueous content and a greater tendency to ionize than iron, and are used for their ability to control anode corrosion reactions. However, in systems where corrosive agents including water, oxygen and hydrogen sulfide coexist.

Easily soluble in water means that metal ions are generated, and when hydrogen sulfide attacks these ions, sulfides of the metal are immediately generated. This weakens the interfacial interaction between the vehicle and these anticorrosive pigments, resulting in accelerated corrosion reactions under the coating. In other words, it is difficult for rust-preventing pigments to react with hydrogen sulfide;
Furthermore, it is a necessary requirement that it is difficult to dissolve in water.

Further, it is preferable that the pH of the water dissolved in the pigment is slightly acidic, measured according to JIS-5101, from 6 to 7. Hydrogen sulfide is slightly acidic when dissolved in water. If these substances are dissolved in water and the pH becomes alkaline, they will serve to attract more hydrogen sulfide water, which is slightly acidic, which is disadvantageous for anticorrosion properties. Conversely, if the pH is less than 6, corrosion of steel will occur in an acidic region.
A low pH is not preferable because it promotes corrosion by itself.

A preferred antirust pigment that satisfies these conditions is 1.
For example, barium chromate (Ha(:rOa)), zinc chromate ZTO type (ZnCrO* 4Zn(OH)
2).

Aluminum phosphomolyftate (1003” P 20
Examples include S.Al, 03).

The amount of these ingredients to be blended is 50 to 200 parts by weight as a filler and 3 to 40 parts by weight as a rust preventive pigment, based on 100 parts by weight of the vehicle component.

If the amount of filler is less than 50 parts by weight, the coating film will not be practical in terms of strength and will have poor impact and bending properties. Also, 200
If it exceeds 1 part by weight, the amount of binder will be less than the amount of filler, which is undesirable because there will be insufficient binder and a uniform film will not be formed, causing defects such as pinholes, and the physical properties will be insufficient. .

Next, if the amount of the rust preventive pigment is less than 3 parts by weight, the rust preventive property will be insufficient, and if it exceeds 40 parts by weight, the rust preventive pigment will dissolve in water even if the insoluble content is suppressed to 0.3% or less. This is not preferable because the absolute amount of pigment increases and the rust prevention property deteriorates.

In addition to the above-mentioned essential components, the anticorrosive coating composition according to the present invention may contain appropriate additives such as anti-cissing agents, anti-sagging agents, and spreading agents. In order to improve workability, solvents can also be added as necessary. Furthermore, in order to adjust the curing time of the paint, 2-ethyl-4-methylimidazole,
2゜4.6-) Curing accelerator such as lith(dimethylaminomethyl)phenol 1 Reactive diluent, dicanol DLO5
It is also possible to blend additives such as a viscosity modifier such as (manufactured by Mitsubishi Gas Chemical Co., Ltd.).

Hereinafter, the present invention will be explained in more detail according to Examples.

Examples First of all, Synthesis Example B02 of a modified aliphatic polyamine which is a curing agent used in preparing the anticorrosive coating composition according to the present invention. B03
．． 806. The methods for synthesizing PO2, CO2 and BO2 and the methods for synthesizing polyamideamine (I), polyamideamine (■) and polyamideamine adduct which are curing agents corresponding to JP-A No. 61-1132584 are shown below.

[Synthesis of BO2] Gascamine G3, which is a condensate of soda-xylene diamine and epichlorohydrin, was added to a three-bottle flask equipped with a stirrer.
28 (manufactured by Mitsubishi Gas Chemical Co., Ltd., active hydrogen equivalent: 55, molecular weight: 320) was added to 320 g (1 mol) of Nirasan Epiol B (Japanese), which is a butyl glycidyl ether, while heating and stirring at 80°C in a nitrogen stream. Manufactured by Yushisha, molecular weight 1
30) 28 g (0.2 mol) was added dropwise over one sowing period, and after the addition was completed, the reaction was further stirred at 80° C. for 2 hours to complete the reaction. The active hydrogen equivalent of BO2, which is the modified aliphatic polyamine produced, was 61.

[Synthesis of BO3] 320 g (1 mol) of 6328 was reacted with 39 g (0.3 mol) of Nirasaneviol B in exactly the same manner as the synthesis of BO2 to obtain BO3, which is a modified aliphatic polyamine. The active hydrogen equivalent of BO3 was 62.

[Synthesis of BO6] 320 g (1 mol) of 0328 was reacted with 78 g (0.8 mol) of Nirasaneviol B in exactly the same manner as for the synthesis of 802 to produce 806, which is a modified aliphatic polyamine.
I got it. The active hydrogen equivalent of BO6 was 85.

[Synthesis of BO2] In exactly the same manner as the synthesis of 802, the glycidyl ether to be added to 0328 was added to phenylglycidyl ether Nirasanepiol P (manufactured by NOF Corporation, molecular weight: 50).
320g (1 mol) of G328 and 30g (
0.2 mol) of Nirasaneviol P was reacted to obtain PO2, which is a modified polyamine. The active hydrogen equivalent of BO2 was 62.

[Synthesis of C02] In exactly the same manner as the synthesis of BO2, the glycidyl ether to be added to G328 was converted into 0-cresol glycidyl ether J.
Shideru Heroxy WCll12 (I C Fist Ai
Made by Japan Co., Ltd., molecular weight 165), 320g (1
mol) of G328 was reacted with 33 g (0.2 mol) of heroxylic acid C82 to obtain CO2, which is a modified polyamine.

The active hydrogen equivalent of CO2 was 63.

[Synthesis of BO2] In exactly the same manner as the synthesis of BO2, the glycidyl ether added to 0328 was changed to 2-ethylhexyl glycidyl ether (Evolai) M-800 (manufactured by Kyoeisha Yushi Co., Ltd., molecular weight 184), and 320 g (0,1 mol) of G328 and 38.8g (0.2 mol) of Evolite M
-800 is reacted with B, which is a modified aliphatic polyamine.
Obtained O2. The active hydrogen equivalent of BO2 was 63.

[Synthesis of polyamidoamine (I)]

In a three-loaf flask equipped with a Kuehler dehydrator and a stirrer, 578 g of Versadim 9218 (dimer acid manufactured by Henkel Japan, acid value 195) (equivalent to 1 mole as a calculated value, theoretical value is seog) and ethylenediamine 120
g (2 mol) and stirred while gradually heating.

The temperature was raised from 180°C to 200°C over about 4 hours, and the water produced by the reaction was dehydrated in a Kuehler dehydrator, and the acid value of the resin was measured when 36g of theoretical water had been dehydrated. After confirming that the acid value was 3 or less, the reaction was terminated.

The active hydrogen equivalent of the polyamide amine (I) produced is 10
It was 7.

[Synthesis of polyamidoamine (II)]

In the same apparatus as used for the synthesis of polyamide amine (I), 576 g (1 mol) of Versadime #216 and 272 g (2 mol) of ■-xylene diamine were heated with stirring, and 1
The temperature was raised from 60°C to 200°C for about 3 hours, and while constantly removing reaction water from the system, it was confirmed that about 38g of water came out of the system and that the ugliness value was 3 or less. The reaction was terminated. The active hydrogen equivalent of the obtained polyamide amine (II) was 141.

[Synthesis of polyamide amine adduct]

7.1 g of the above polyamide amine (I) was placed in a three-bottle flask equipped with a stirrer, heated to 80°C in a nitrogen stream, and while stirring, Epikote 1001 (manufactured by Yuka Shell Co., Ltd., molecular weight 900) was added. .9 g was added over 1 hour, and after the addition was completed, the reaction was further stirred at 80°C for 2 hours to complete the reaction, and a polyamide amine adduct ((epoxy group/active hydrogen) ratio = 1.2/1) was synthesized. .

Next, Examples 1 to 27 of anticorrosive coating compositions according to the present invention.
As comparative examples, Comparative Examples 1 to 4 corresponding to JP-A-81-11112584 and Comparative Example 5 other than JP-A-81-11125134 are collectively shown in Table 1. Epoxy resins used in comparative examples are shown in Table 2, fillers in Table 3, and antirust pigments in Table 4.

The anticorrosive coating composition in Table 1 was prepared using xylene/butyl cellosolve/methyl isobutyl ketone/n-butanol (50/3
G/1G/10) was dissolved in 120 parts by weight of a mixed solvent, and a film having a thickness of 100 IL was coated on a steel plate using an airless coating machine. The steel plate is 70 ■ Houji X 150 ■ Director X 0.
An 8 gm thick blank steel plate polished with #400 paper was used. Drying conditions: 20℃ x 1 day +50℃
*24 hours.

Adhesion, hardness, bending, smooth sprayability, and methanol water immersion of the dried coating film were tested in accordance with API-RP-5L-2. Furthermore, it was immersed in 80° C. saturated hydrogen sulfide water for 2000 hours and an adhesion test was conducted to examine hydrogen sulfide resistance. The results were as shown in Table 5.

As is clear from the results in Table 5, when the composition of the present invention is used as a coating composition for corrosion protection of steel materials, extremely good results that have never been seen before can be obtained in a 60°C saturated hydrogen sulfide water immersion test. .

Effects of the Invention As is clear from the Examples, the anticorrosive paint composition according to the present invention significantly improves the hydrogen sulfide resistance at 60°C compared to conventional anticorrosion paint compositions.

Claims (1)

[Claims] 1. An epoxy resin having 1 to 2 oxirane rings per molecule and having an epoxy equivalent of 180 to 2,500 obtained by the addition reaction of bisphenol A and epihalohydrin, and m-xylene diamine and epichlorohydrin. Reaction with a modified polyamine obtained by reacting and adding at least one of butyl glycidyl ether, phenyl glycidyl ether, o-cresyl glycidyl ether, and ethylhexyl glycidyl ether at a ratio of 0.2 to 0.6 mol per mol of the condensate. 100 parts by weight of a vehicle having a reaction equivalent ratio of epoxy resin to modified polyamine of 0.8/1 to 1.4/1, 50 to 200 parts by weight of a filler inert to hydrogen sulfide, and JIS - Insoluble matter by K-5101 is 0.3% or less and the pH of the dissolved water is 6.0 to 7.
．． An anticorrosion paint composition comprising 3 to 40 parts by weight of a rust preventive pigment of 0. 2. The filler inert to hydrogen sulfide is at least one selected from the group consisting of carbon black, titanium oxide, aluminum powder, silicon oxide, aluminum oxide, and magnesium oxide, according to claim 1. Anticorrosive paint composition. 3. Rust-preventing pigments are barium chromate and zinc chromate Z
The anticorrosive coating composition according to claim 1, which is at least one selected from the group consisting of TO type and aluminum phosphomolybdate.