JPH07145349A - Coating composition for rusty surface and rust prevention and corrosion prevention of steel structure therewith - Google Patents

Abstract

PURPOSE:To obtain a coating composition excellent in intimate adhesion to an imperfectly derusted steel sheet, an effect of preventing its corrosion, etc., by using a substance having a disulfide bond in the molecule as the essential component. CONSTITUTION:This coating composition is prepared by using a substance having a disulfide bond in the molecule as the essential component and optionally mixing this compound with a base resin component such as an epoxy resin (e.g. bisphenol A derived epoxy resin). Desirable examples of the above substances include an epoxy-terminated polysulfide compound having a disulfide bond in the skeleton and a mercapto-terminated polysulfide compound having a plurality of disulfide bonds in the skeleton (e.g. trademark Thikol LP-2, a product of Toray Thiokol Kk).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rust surface coating composition and a method for preventing rust and corrosion of a steel structure using the rust surface coating composition, and in particular, it has excellent adhesion and adhesion to a steel sheet having rust remaining. TECHNICAL FIELD The present invention relates to a rust surface coating composition and a method for preventing corrosion and corrosion of a steel structure using the same.

[0002]

Steel products are widely used in offshore structures, harbor facilities, ships, construction / civil engineering structures, automobiles, mechanical equipment, railway vehicles, generators, large transformers and the like. However, if left in the natural environment,
There is a problem that so-called "rust" occurs when trying to return to a more stable iron oxide state.

Offshore structures, port facilities, etc.
For the purpose of preventing deterioration of ships, construction / civil engineering structures, automobiles, machinery, railway vehicles, generators, large transformers, etc.
Anti-corrosion and anti-corrosion coating is widely used. The corrosion resistance, durability, adhesion and adhesiveness of this rust / corrosion preventive coating after aging are
The degree of rust removal has a great effect. If the rust is not removed sufficiently, the coating film will have poor adhesion and peeling or rust of the coating film will occur very quickly. Therefore, the highest level of rust removal is standardized in rust / corrosion coating construction.

However, in reality, offshore structures, port facilities, ships, construction / civil engineering structures, automobiles, mechanical equipment,
Depending on the conditions such as the environment and parts of steel structures such as railway cars, generators, and large transformers, high-level rust removal work itself is difficult, and there are many coating problems due to inadequate pretreatment. Further, in recent years, due to lack of workers engaged in rust removal work, there has been a strong demand for simplification of rust removal work.

Therefore, an object of the present invention is to provide a coating composition for a rust surface which is excellent in adhesion and adhesion to a steel sheet on which rust remains.

Another object of the present invention is to provide a method for preventing rust and corrosion of steel structures.

[0007]

As a result of earnest research in view of the above object, the inventors of the present invention have found that a composition containing a substance having a disulfide bond in the molecule has an adhesive force to a steel sheet on which rust remains. Further, they have found that they have excellent adhesive strength and have arrived at the present invention.

That is, the rust surface coating composition of the present invention is characterized by containing a substance having a disulfide bond in the molecule.

The steel structure rust / corrosion prevention method of the present invention is characterized in that the above-mentioned rust surface coating composition is applied to the steel structure.

The present invention is described in detail below. [1] Rust surface coating composition The rust surface coating composition of the present invention contains a substance having a disulfide bond in the molecule.

(1) Substance Having Disulfide Bond in Molecule In the present invention, a substance having a disulfide bond in the molecule (hereinafter simply referred to as “disulfide bond-containing substance”) is a substance having a disulfide bond (-). SS-) 1
It is a substance having one or two or more. Examples of the substance containing a disulfide bond include, for example, dimethyl disulfide,
Diethyl disulfide, dipropyl disulfide,
Dibutyl disulfide, dioctyl disulfide,
Dibenzyl disulfide, diheptyl disulfide, dicyclohexyl disulfide, didodecyl disulfide, diamyl disulfide, 2,2'-dithiodibenzoic acid, 2,2'-dithiodibutanoic acid, 2,2 '
-Dithiodipropionic acid, or an epoxy group-terminated polysulfide compound, a mercaptan-terminated polysulfide compound, a hydroxyl group-terminated polysulfide compound, an acryl-terminated polysulfide compound, an isocyanate-terminated polysulfide compound, and the like.

Among the above disulfide bond-containing substances, epoxy group-terminated polysulfide compounds and mercaptan-terminated polysulfide compounds are preferable.

The epoxy group-terminated polysulfide compound is a substance having an epoxy group at the terminal and having a disulfide bond in the skeleton, but a compound having a plurality of disulfide bonds in the skeleton is preferable. Particularly preferred epoxy-terminated polysulfide compound, in a molecule _{(-CH 2 CH 2 OCH 2 OCH} 2 CH 2 SS-) n,
Or _{(-CH 2 CH 2 OCH 2 CH} 2 OCH 2 CH 2
Examples include substances having two or more polysulfide bond-containing structural units represented by SS-) _n (2 ≦ n) and having an epoxy group at the terminal.

Commercially available products of such epoxy group-terminated polysulfide compounds are "FLEP-10", "FLEP-50", and "FLEP" manufactured by Toray Thiokol Co., Ltd.
-60 "," FLEP-80 "," FLEP-120 "
X "," FVD-103X "," FVD-105X ",
"FVD-123X", "FLEP-125X", "F
"LEP-410C", "FLEP-410XA", "F
"VD-423C" and "FVD-423XA", "ELP-612" manufactured by Morton International,
"ZL-1856" and "EPOXY-LP ADDU
CTS "etc. can be mentioned.

The mercaptan-terminated polysulfide compound is a substance having a mercaptan group at the terminal and a plurality of disulfide bonds in the skeleton. Preferred mercaptan terminated polysulfide _{compounds, -CH 2 CH 2 OCH 2 OCH} 2 CH 2 SS- in the molecule,
Or _{-CH 2 CH 2 OCH 2 CH 2} OCH 2 CH 2 S
Examples thereof include a substance having a polysulfide bond-containing structural unit represented by S- and having a mercaptan group at the terminal.

Commercial products of such mercaptan-terminated polysulfide compounds include "Thiocol LP-2" and "Thiocol LP-3" manufactured by Toray Thiokol Co., Ltd.
"Thiocol LP-12", "Thiocol LP-3"
1 "," Thiocol LP-32 "," Thiocol LP-
55 "," Thiocol LP-56 "," Thiocol LP
-70 "and" Thiocol LP-72 "," ZL-2264 "manufactured by Morton International, Inc., and the like.

(2) Base resin component The above-mentioned substance having a disulfide bond in the molecule is added to a base resin component such as an epoxy resin, a urethane resin, a polyester resin, an acrylic resin or a fluororesin, if necessary. As a result, a composition having improved adhesion and adhesion to the rust surface can be obtained. Particularly, it is preferable to use it by adding it to an epoxy resin.

Examples of the epoxy resin include bisphenol A type epoxy resin, bisphenol AD type epoxy resin, bisphenol S type epoxy resin, halogenated bisphenol A type epoxy resin and bisphenol F type epoxy resin.

When the above base resin component is blended, the proportion of the disulfide bond-containing substance is 10
2 to 200 parts by weight, especially 5 to 100 parts by weight
It is preferably part by weight. If the amount of the substance containing a disulfide bond is less than 2 parts by weight, the effect of improving the adhesiveness to the rust surface is not sufficient, while if it exceeds 200 parts by weight, the performance of the base resin may not be exhibited.

(3) Curing Agent A curing agent can be added to the rust surface coating composition of the present invention, if necessary. For example, when an epoxy resin is added to a substance containing a disulfide bond, or when an epoxy group-terminated polysulfide compound is used as the substance containing a disulfide bond, a curing agent that reacts with the epoxy group is used.

Examples of the curing agent which reacts with the epoxy group include triethylenetetramine, isophoronediamine, m-xylenediamine, cyclohexylamine, N-cyanoethylxylylenediamine, N-aminoethylpiperazine, N-benzylethylenediamine, Polyamide / modified polyamidoamine (for example, "Adeka Hardener EH-355" manufactured by Asahi Denka Co., Ltd., "Tomade # 225-E80" and "Tomade # 423" manufactured by Fuji Kasei Co., Ltd., Sanwa Chemical Industry Co., Ltd. "Sunmide 390-70" and "Sunmide 305-70" manufactured by Co., Ltd.
X "," Zenamide 490 "manufactured by Henkel Hakusui Co., Ltd.), and modified polyamine (for example, Asahi Denka Co., Ltd.)
"ADEKA HARDNER EH-220", "ADEKA HARDNER EH-227" and "ADEKA HARDNER EH-2"
30 "," Araldite X1 "manufactured by Ciba-Geigy Co., Ltd.
101 "," Epicure-3012 "and" Epomate N-001 "manufactured by Yuka Shell Epoxy Co., Ltd.," Daitokural HD-Q "," Daitokural HD-801CB "and" Daito "manufactured by Daito Sangyo Co., Ltd. Clar X-143
6 "," Daitokural X-1777A "and" Daitokural X-2392 "," Fujicure- # 4011 "and" Fujicure- # 402 "manufactured by Fuji Kasei Kogyo Co., Ltd.
5 "," Fujicure- # 5011 "and" Fujicure-
# 5420 ", manufactured by Sanwa Chemical Industry Co., Ltd.," Sunmide E- "
1000 "," Sunmide W-3000 "," React CA-101 "manufactured by Sanyo Chemical Industry Co., Ltd.) and the like.

When an epoxy resin is added to a substance containing a disulfide bond, or when an epoxy group-terminated polysulfide compound is used as the substance containing a disulfide bond, the epoxy resin may be mixed with the above-mentioned curing agent or in place of the curing agent. Primary amines can be used.

Examples of the tertiary amines include triethylamine, benzyldimethylamine, 2,4,6-tris (dimethylaminomethyl) phenol, ketimine, benzyldimethylamine and dimethylcyclohexylamine.

The amount of the above-mentioned curing agent and / or tertiary amine compounded may be appropriately set according to the epoxy equivalent of the epoxy group in the composition, but the epoxy resin is a substance having a disulfide bond in the molecule. When blended, the amount is preferably 1 to 100 parts by weight with respect to 100 parts by weight of the epoxy resin. When the epoxy group-terminated polysulfide compound is used, the amount is preferably 1 to 100 parts by weight based on 100 parts by weight of the epoxy group terminated polysulfide compound.

(4) Other components The rust surface coating composition of the present invention may further contain, if necessary,
A substance having compatibility or affinity (for example, reactive diluent, non-reactive diluent, solvent) or the like can be added.

When a reactive diluent, a non-reactive diluent, or a solvent is added, the amount of addition varies somewhat depending on the type of substance used, but the total amount of the disulfide bond-containing substance + base resin component is 100 parts by weight. On the other hand, it is preferably 1 to 200 parts by weight.

In addition to the above components, the rust surface coating composition of the present invention may further contain aluminum powder, aluminum hydroxide, aluminum stearate, aluminum polyphosphate, zinc polyphosphate, and aliphatic carvone, if desired. Amine salts of acids, graphite, carbon black, wollastonite, kaolin, clay, titanium oxide, yellow iron oxide, scaly iron oxide, micaceous iron oxide, silica sand, silica, cyanine green, cyanine blue, talc, calcium carbonate , Bentonite, mica, organic bentonite, mica powder, yellow lead, lead cyanide lead, lead chromate, lead zincate,
Flaxseed oil, zinc dust, zinc white, zinc chromate, rouge,
Gilsonite, coal tar pitch, manganese naphthenate, cobalt naphthenate, lead naphthenate, phosphoric acid, magnesium silicate, navy blue, ultramarine, quartz powder, barium sulfate, iron black, etc. Additives such as a rust pigment, a coloring agent, an anti-skinning agent, a dispersant, and an anti-sagging agent can be added.

[2] Method for Preventing Corrosion / Corrosion of Steel Structures The method for preventing corrosion / corrosion of steel structures of the present invention is to apply the above-mentioned rust surface coating composition to the surface of a steel plate or the like. The steel plate may be in a state where rust is generated and remains,
It may be in a new state without rust. The rust surface coating composition is mainly used as an undercoat, but is not limited thereto, and can be used as an overcoat or an intermediate coat, and is applied to a thickness of 1 to 3000 μm, particularly 10 to 1000 μm. preferable.

[0029]

As described above, since the rust surface coating composition of the present invention contains a substance having a disulfide bond in the molecule, it is suitable for a steel sheet in which rust remains. Exhibits adhesion and adhesion. Such an effect is obtained because the disulfide bond in the polysulfide compound is α-hydrated iron (α), which is the main component of iron rust.
It is becoming clear that it is due to the chemisorption interaction with the oxygen atom of (FeOOH). Such a substance containing a disulfide bond exhibits good adhesion and adhesion to rust.

[0030]

The present invention will be described in more detail by the following examples.

Example 1 As a substance having a disulfide bond in the molecule, 39.2 parts by weight of an epoxy group-terminated polysulfide compound (“FLEP-125X” manufactured by Toray Thiokol Co., Ltd.),
Talc as an additive ("SSS" manufactured by Nippon Talc Co., Ltd.)
After mixing and dispersing 20 parts by weight and 20 parts by weight of titanium oxide (“Taipec CR-50” manufactured by Ishihara Sangyo Co., Ltd.), 25 parts by weight of toluene and 5 parts by weight of isobutyl alcohol as a solvent in a batch type desktop sand mill, 8.8 parts by weight of modified polyamidoamine (“SANMIDE 390-70” manufactured by Sanwa Chemical Industry Co., Ltd.) was added as a curing agent and mixed to obtain a rust surface coating composition. The performance of the coating composition for rust surface thus obtained was evaluated by the following method. The results are shown in Table 1 together with the blends and their blending ratios.

Measurement of Adhesion to Rust Surface 3.2 mm × 70 mm × 150 mm steel plate (SS40
0) was prepared and exposed to the coastal industrial zone (Ichihara City, Chiba Prefecture, Chikusa Coast) for 6 months to rust it. 80% of red floating rust on this steel plate with an electric wire brush
This was removed to some extent and polished to the point where a part of the shiny base of iron was visible, and this was used as a type 2 keren plate. In addition, about 50% of the red floating rust was removed with a manual wire brush, and the ground was polished to the extent that only black rust was visible, and this was used as a Class 3 Keren plate.

The rust-remaining steel sheet thus obtained was coated with the rust surface coating composition so that the coating thickness was 50 μm, and after curing at 20 ° C. for 7 days, the sea berth ( It was exposed for 6 months (March-September 1993) at a location 1.5 m from the coast of Toray Co., Ltd. on the Chigusa coast in Ichihara city, Chiba prefecture. The evaluation of the adhesion of the coating film after 2 months and 6 months has been carried out by the "General test method of paint, cross-cut tape method" (JI
SK5400.8.5.2).

Measurement of Corrosion Progress Inhibitory Effect A type 2 keren plate and a type 3 keren plate were prepared in the same manner as the measurement of the adhesion to the rust surface. On the obtained keren board,
After applying the rust surface coating composition to a coating thickness of 50 μm and curing it at 20 ° C. for 7 days, from the bottom of the keren board 1 /
A cross cut was put in the area 3 and exposed for 6 months (March-September 1993) at a position 1.5 m from the seashore of the sea berth (inside the Toray Co., Ltd. of Chikusa coast, Chiba prefecture). The progress of rust after 2 months and 6 months was evaluated by the state of the coating film in the cross-cut portion and other portions.

Comparative Example 1 Bisphenol A type epoxy resin ("Epicoat 1001-X-70" manufactured by Yuka Shell Epoxy Co., Ltd.) 42.2
After mixing and dispersing parts by weight and the additive and solvent described in Example 1 in the same manner as in Example 1, a modified polyamidoamine (manufactured by Sanwa Chemical Industry Co., Ltd., “Sunmide 390”) was used as a curing agent.
-70 ") 12.3 parts by weight were added and mixed to obtain a rust surface coating composition. The performance of the coating composition for a rust surface thus obtained was evaluated by the same method as in Example 1. The results are shown in Table 1 together with the blends and their blending ratios.

Table 1 Composition (parts by weight) Example 1 Comparative example 1 Substance having disulfide bond in molecule FLEP-125X 39.2- Bisphenol type epoxy resin Epicoat 1001-X-70-42.2 Additive talc 20 20 Titanium oxide 20 20 Solvent Toluene 25 25 Isobutyl alcohol 55 Curing agent Sunmide 390-70 8.8 12.3 Performance Adhesion to rust surface ⁽¹⁾ 2nd type Keren plate 2 months after exposure 25/25 23/25 6 months after exposure 25/25 23 / 25 3 type keren plate 2 months after exposure 25/25 19/25 6 months after exposure 24/25 10/25 Evaluation of inhibition of corrosion progress ⁽²⁾ 2 type kelen plate 2 months after exposure ○ ○ 6 months after exposure ○ × × 3 type Keren board 2 months after exposure ○ ○ 6 months after exposure ○ ×

Note) (1): Cuts are made in a grid pattern (25 squares of 2 mm x 2 mm), and the number of squares remaining after peeling off the adhesive tape on this grid is shown. It was (2): Evaluation criteria ○ ... Cross-cut part is almost good, and other parts are completely the same as before exposure. △: Blisters are considerably generated in the cross-cut part, but other parts are the same as before exposure. ×: A large number of bulges are generated on the surface of the coating film in the cross-cut portion and other portions. XX: A state in which many bulges are generated on the surface of the coating film at the cross-cut portion and other portions and red rust is generated on the surface.

As is clear from Table 1, the rust surface coating composition of the present invention has good adhesion to steel plates regardless of the degree of swelling, and no decrease in adhesion with time is observed. In Comparative Example 1, the adhesiveness is considerably lowered with the passage of time, and particularly, the adhesiveness is remarkably reduced with respect to the third-class cleaning plate in which a large amount of rust remains. Further, the rust surface coating composition of the present invention has no deterioration in rust / corrosion preventive performance over time even if the degree of swelling is not sufficient, and suppresses corrosion, whereas it is obtained in Comparative Example 1. The composition coated with
Even in the second class keren plate, which has a relatively small amount of rust, swelling and rust occur after 6 months of exposure and severe corrosion progresses.

Example 2 30.0 parts by weight of an epoxy group-terminated polysulfide compound (“FLEP-60” manufactured by Toray Thiokol Ltd.) as a substance having a disulfide bond in the molecule, and talc as an additive (Nippon Talc (Ltd.) ) "SSS") 20
20 parts by weight and titanium oxide (“Taipec CR-50” manufactured by Ishihara Sangyo Co., Ltd.), and toluene 20 as a solvent.
After mixing and dispersing 1 part by weight and 10 parts by weight of isobutyl alcohol in a batch-type tabletop sand mill, modified polyamine (Fuji Cure- # manufactured by Fuji Kasei Kogyo Co., Ltd.) as a curing agent.
5420 ") and 8.9 parts by weight were added and mixed to obtain a rust surface coating composition. The performance of the coating composition for rust surface thus obtained was evaluated by the following method. The results are shown in Table 2 together with the blends and their blending ratios.

Measurement of Adhesion to Rust Surface A type 2 keren plate and a type 3 keren plate were prepared in the same manner as the measurement of the adhesion to the rust surface. On the obtained keren board,
After coating the rust surface coating composition to a thickness of 50 μm and curing it at 20 ° C for 7 days, it is 1.5 m from the seashore of the sea berth (inside Toray Co., Ltd., Chikusa Coast, Ichihara City, Chiba Prefecture).
Was exposed for 6 months (March-September 1993). 6
The adhesion of the coating film after the lapse of months was evaluated in accordance with "General Test Method for Paint, Cross-cut Tape Method" (JIS.K.5400.8.5.2).

Comparative Example 2 30.0 parts by weight of a bisphenol A type epoxy resin (“Epicoat 828” manufactured by Yuka Shell Epoxy Co., Ltd.), the additive and the solvent described in Example 2 were added in the same manner as in Example 2. After mixing and dispersing, modified polyamine (“Fujicure # 5420” manufactured by Fuji Kasei Kogyo Co., Ltd.) as a curing agent 12.8
Parts by weight were added and mixed to obtain a rust surface coating composition. The performance of the coating composition for a rust surface thus obtained was evaluated by the same method as in Example 2. The results are shown in Table 2 together with the blends and their blending ratios.

Comparative Example 3 The performance of a commercially available modified epoxy resin-based rust preventive coating (manufactured by Company A) was evaluated by the same method as in Example 2. The results are shown in Table 2.

Table 2 Composition (parts by weight) Example 2 Comparative example 2 Comparative example 3 Substance having disulfide bond in molecule FLEP-60 30.0- bisphenol type epoxy resin Epicoat 828-30.0- Additive talc 20 20-Oxidation Titanium 20 20- Solvent Toluene 20 20-Isobutyl alcohol 10 10- Curing agent Fujicure- # 5420 8.9 12.8- Commercial modified epoxy resin rust preventive paint manufactured by Company A--100 Adhesion to rust surface after 6 months of performance exposure 2nd type keren board 25/25 24/25 22/25 3rd type keren board 23/25 3/25 5/25

As is clear from Table 2, the plate coated with the rust surface coating composition of the present invention exhibits good and stable adhesion even if the rust removal treatment is not sufficient. On the other hand, in Comparative Examples 2 and 3, the adhesiveness changes considerably depending on the degree of swelling, and particularly the adhesiveness to the three types of swelling plates where a large amount of rust remains is extremely poor.

Example 3 As a substance having a disulfide bond in the molecule, 57.5 parts by weight of an epoxy group-terminated polysulfide compound (“FLEP-410C” manufactured by Toray Thiokol Co., Ltd.),
Talc as an additive ("SSS" manufactured by Nippon Talc Co., Ltd.)
After mixing and dispersing 20 parts by weight and 20 parts by weight of titanium oxide (“Taipec CR-50” manufactured by Ishihara Sangyo Co., Ltd.), 10 parts by weight of toluene and 2 parts by weight of isobutyl alcohol as a solvent in a batch type tabletop sand mill, Modified polyamine as a curing agent ("Daito Clar H" manufactured by Daito Sangyo Co., Ltd.)
DQ ") 10.4 parts by weight were added and mixed to obtain a rust surface coating composition. The performance of the coating composition for rust surface thus obtained was evaluated by the following method. The results are shown in Table 3 together with the blends and their blending ratios.

Measurement of Corrosion Progress Inhibitory Effect A type 2 keren plate and a type 3 keren plate were prepared in the same manner as the measurement of the adhesion to the rust surface. On the obtained keren board,
After applying the rust surface coating composition to a coating thickness of 50 μm and curing it at 20 ° C. for 7 days, from the bottom of the keren board 1 /
Cross-cuts at 3 cm intervals were placed in 3 and exposed for 3 months (June-September 1993) at a location 1.5 m from the coast of Seaverse (inside Toray Co., Ltd., Chikusaigan, Ichihara, Chiba). did. The progress of rust after 3 months was evaluated by the state of the coating film in the cross-cut portion and other portions.

Comparative Example 4 30.0 parts by weight of bisphenol A type epoxy resin ("Epicoat 1004" manufactured by Yuka Shell Epoxy Co., Ltd.) was dissolved in 20.8 parts by weight of cyclohexanone, and talc (Japan) was added as an additive. "SSS" manufactured by Talc Co., Ltd.) 2
0 parts by weight and 20 parts by weight of titanium oxide (“Taipec CR-50” manufactured by Ishihara Sangyo Co., Ltd.), and toluene 1 as a solvent.
After mixing and dispersing 5 parts by weight and 4 parts by weight of isobutyl alcohol in a batch-type tabletop sand mill, modified polyamine (manufactured by Daito Sangyo Co., Ltd. “Daito Clar HD
-Q ") 13.9 parts by weight were added and mixed to obtain a rust surface coating composition. The performance of the coating composition for a rust surface thus obtained was evaluated by the same method as in Example 3. The results are shown in Table 3 together with the blends and their blending ratios.

Comparative Example 5 The performance of a commercially available modified epoxy resin rust preventive coating (manufactured by Company B) was evaluated by the same method as in Example 3. The results are shown in Table 2.

Table 3 Composition (parts by weight) Example 3 Comparative example 4 Comparative example 5 Substance having disulfide bond in molecule FLEP-410C 57.5- bisphenol type epoxy resin Epicoat 1004-30.0- Additive talc 20 20-Oxidation Titanium 20 20- Solvent Cyclohexanone-20.8-Toluene 10 15-Isobutyl alcohol 24 -Curing agent Daito Clar HD-Q 10.4 13.9- Commercially available modified epoxy resin rust preventive paint B--100 Evaluation of inhibition of progress of performance corrosion 2nd Keren board 3 months after exposure ○ △ × 3rd Keren board 3 months after exposure ○ △ × ×

As is clear from Table 3, even if the keren board coated with the rust surface coating composition of the present invention was exposed in the summer near the coast where the amount of incoming salt was high, it did not depend on the degree of rust removal treatment. Good rust and corrosion protection. For it,
The rust-remaining steel sheet coated with the epoxy resin coating of Comparative Example 4 having no disulfide bond in the molecule and the rust preventive coating of Comparative Example 5, which is generally commercially available for repairing iron structures, has a rust of 3 months. Corrosion progresses on exposure.

[0051]

As described above in detail, since the rust surface coating composition of the present invention contains a substance having a disulfide bond in the molecule, the adhesion to the steel sheet on which rust remains and Excellent adhesion. Further, by applying such a rust surface coating composition of the present invention to a rusty steel structure, an effect of suppressing corrosion can be obtained.

The rust surface coating composition of the present invention is particularly effective for applications where a high degree of rust removal work is difficult or for applications where simplification of the rust removal work is required.

Such a rust surface coating composition of the present invention is a coating for marine structures, a coating for port facilities, a coating for ships,
It is effective as a paint for plants, a paint for bridges, a paint for automobiles, a paint for railway vehicles, a paint for machinery and equipment, an industrial paint and a paint for construction and civil engineering. Further, the rust surface coating composition of the present invention has good performance for the above-mentioned paint even when it is used for other than the rust surface, such as a new iron plate.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Seiichi Nose 2-3, Chikusaigan, Ichihara-shi, Chiba Torayachiol Co., Ltd. Chiba factory (72) Katsumi Ohno 2-3 East, Chikusaigan, Ichihara-shi, Chiba Chiba Factory, Rethiocol Co., Ltd.

Claims (5)

[Claims] 1. A rust-face coating composition comprising a substance having a disulfide bond in its molecule. 2. The rust surface coating composition according to claim 1, wherein the composition contains a substance having a disulfide bond in the molecule and an epoxy resin. object. 3. The rust surface coating composition according to claim 1, wherein the substance having a disulfide bond in the molecule is an epoxy group-terminated polysulfide compound or a mercaptan-terminated polysulfide compound. Coating composition. 4. The rust surface coating composition according to claim 1, wherein the substance having a disulfide bond in the molecule is an epoxy group-terminated polysulfide compound having two or more disulfide bonds in the molecule. A coating composition for a rust surface, which is characterized by: 5. A method for preventing corrosion and corrosion of a steel structure, which comprises applying the coating composition for a rust surface according to any one of claims 1 to 4 to a steel structure.