JP3408188B2 - Corrosion protection method with organic material - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for coating a metal surface or a concrete surface containing reinforcing bars with an organic material to prevent corrosion, and particularly to a metal surface not only in the air but also in a wet state or in water or a concrete surface containing reinforcing bars. On the other hand, the present invention relates to a coating anticorrosion method using an organic material, which maintains a good adhesion state by stable and favorable resin adhesion and prevents corrosion deterioration of a structure for a long period of time.

[0002]

2. Description of the Related Art Conventional methods for preventing corrosion of a metal surface or a concrete surface containing reinforcing bars (hereinafter simply referred to as a metal surface) include generally painting, lining, concrete coating, and petrolatum lining. , Etc., and many documents are shown (for example, Corrosion Prevention Handbook). In addition, in the corrosion prevention method in the outdoors where the corrosion is severe, especially in corrosive environments such as harsh water, repeated dry-humidity, or high humidity. Corrosion prevention methods for metal surfaces are quite limited among the above corrosion prevention methods (for example, Coastal Development Technology Center; Port Steel Structure Corrosion Protection and Repair Manual etc.). Further, as a method for preventing corrosion of a metal which has been exposed to these environments and has already been corroded, underwater coating (for example, Japanese Unexamined Patent Publication No. Hei 2
No. 248532, Japanese Utility Model Publication No. 61-66043), and petrolatum lining (for example, Japanese Patent Laid-Open No. 62-
1830) and concrete coating (for example, Japanese Patent Publication No. 5-45728).

As an anticorrosion method using a material containing a water-absorbing polymer, a corrosion-preventing structure in which a water-absorbing polymer added to a rubber material is attached to a protective cover (Japanese Patent Laid-Open No. 62-78323). There is.

Further, as an anticorrosion method using an uncured resin, a lining method in which a non-woven fabric is impregnated with a urethane type resin or an epoxy type resin and attached thereto (Japanese Patent Laid-Open No. 3-2188).
15).

Further, there has been proposed an anticorrosion processing method (Japanese Patent Laid-Open No. 60-144427) in which a fluid resin is poured into a form frame assembled in advance with a certain gap around the anticorrosion body and covered. There is.

Among the above-mentioned methods for preventing corrosion, the above-mentioned three methods, which have been mentioned as the method for preventing corrosion of an existing structure particularly in a severe corrosive environment, have the following problems.

(1) Underwater coating: The base treatment by blasting is required (SIS-Sa2 or more) and must be applied immediately after the base treatment. Actually, due to a subtle difference in on-site process, partial adhesion failure occurs. Or peeling may occur. Although there is an underwater putty that increases the film thickness, it has the same problem. In addition, since the surface of the coating film is not usually provided with a protective layer, it is directly affected by changes in the environment and external forces, and thus there is a problem in terms of life.

(2) Petrolatum lining: Petrolatum is an excellent anticorrosive material and exhibits a good anticorrosion effect even with a relatively low grade base treatment (SIS-St2), but since the base material is wax, it is protected against corrosion. Adhesion to the body is shown, but adhesion is impossible. Therefore, in an environment in which an external force is applied, there is a problem that, in the long term, a gap is generated between the body to be protected and the anticorrosion layer to cause corrosion.

(3) Concrete coating: Concrete is a material exhibiting alkalinity and is an excellent material for blocking moisture and dissolved oxygen from the environment to prevent corrosion, but it is generally not applied by coating in a humid environment. It is difficult, and in practice, it is widely practiced to assemble a formwork with a certain gap in the body to be protected, pour it into the formwork, and fill and cover. However, in this case, it is difficult to completely fill the gap in the mold even in the recent progress of the dispersion preventing agent. Further, with this method, it is almost impossible to make fine work according to the shape of the corrosion-resistant body, and as a result, a coated body having a considerable weight is obtained. This imposes a heavy load on the body to be protected. Further, in the long term, if the concrete is neutralized due to salt infiltration, etc., and corrosion occurs even partially, the expansion pressure of the rust may cause the concrete layer to crack rapidly and fall off. Further, since concrete is a substance having almost no elasticity, even if the protected food material slightly moves due to external force or heat change, it cannot follow the movement. Therefore, even if the concrete and the anticorrosion surface are in close contact with each other at the beginning of the construction, the concrete and the anticorrosion surface will be separated over time, which will cause corrosion.
In particular, this phenomenon is observed in offshore structures.

Further, the anticorrosion by coating with a rubber material to which a water-absorbing polymer is added can exert excellent water impermeability to a metal having a smooth surface, and can prevent corrosion, but in many cases the actual structure is corroded. There are many irregular irregularities due to welding marks during construction. In this case, the water swelling of the already cured rubber material is insufficient to maintain the close contact, and a good anticorrosion effect cannot be obtained.

The method of impregnating a non-woven fabric with an uncured resin and pasting it cannot remove the water present in the coating, so that poor adhesion of the resin is likely to occur and the strength of the coating layer is weak. Then, long-term coating corrosion protection is difficult.

The method of pouring and coating a fluid resin in a mold is effective for the surface of the body to be protected and smooth in the atmosphere, but in a wet state, the surface of the body to be protected and the resin are protected. Adhesion becomes unstable, especially when a part of the resin is in water, the specific gravity and viscosity of the resin greatly affect the dispersion in the mold, and it is difficult to obtain good and stable corrosion protection.

In order to solve the above-mentioned problems, the present inventors proposed in Japanese Patent Application No. 10-25965 to coat the concrete surface containing a metal or a reinforcing bar with an uncured resin containing a water-absorbing polymer. . As a result, the above problems have been solved to a certain extent, but further anticorrosion effects have been demanded.

Therefore, the object of the present invention is to maintain a good anticorrosion state for a long period of time not only in a new facility but also in a structure that is in a corrosive environment such as water or in a wet state, by good and stable resin adhesion. Another object of the present invention is to provide a coating anticorrosion method using a possible organic material.

[0015]

DISCLOSURE OF THE INVENTION As a result of intensive studies, the present invention has revealed that a concrete surface containing a metal or a reinforcing bar is coated with an uncured resin containing a water absorbing polymer and an oxygen scavenger or an inhibitor. , It was found that the above object can be achieved.

The present invention has been made on the basis of the above findings, and in a method of coating a metal surface or a concrete surface containing reinforcing bars with an organic material to prevent corrosion, the concrete surface containing the above-mentioned metal or reinforcing bars is removed from a water-absorbing polymer. Coating with an uncured resin containing an oxygen agent, the uncured resin
The surface of the uncured resin is pressed while being pressed against the surface.
The present invention provides a method for coating and preventing corrosion of an organic material , which comprises absorbing water with the water-absorbing polymer .

Further, the present invention provides a method for coating a metal surface or a concrete surface containing reinforcing bars with an organic material to prevent corrosion, wherein the concrete surface containing the metal or reinforcing bars is
It is coated with an uncured resin containing a water-absorbing polymer and an inhibitor, and the uncured resin is pressure-bonded to the surface to form the uncured resin.
The water-absorbing polymer which absorbs water on the surface during curing of the cured resin
The present invention provides a method for coating anticorrosion with an organic material, which is characterized by absorbing water with .

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
In the present invention, the metal surface or the concrete surface containing reinforcing bars is coated with an organic material to prevent corrosion. Examples of the metal here include iron, stainless steel, zinc, aluminum and the like.

In the present invention, an uncured resin containing a water-absorbing polymer and an oxygen absorber or an inhibitor is used as the organic material. As the water-absorbent polymer, polyacrylic acid salt type, saponified vinyl acetate / acrylic acid ester copolymer, polyvinyl acetate / maleic anhydride reaction product, crosslinked isobutylene / maleic acid copolymer, polyethylene oxide type, starch / Acrylic acid graft polymer, polyvinyl alcohol type, poly N-vinyl acetamide type, etc. are exemplified. Here, when the water contains a large amount of electrolyte such as seawater, polyvinyl alcohol (PVOH
Type), poly N-vinylacetamide type (PNVA type), and the like, and nonionic water absorbing polymers are preferable. These water-absorbent polymers are preferably added in an amount of 1 to 200 parts by weight based on 100 parts by weight of the uncured resin.

[0020]

As the oxygen scavenger, sodium sulfite, hydrazine or the like is used.

As the inhibitor, at least one selected from orthophosphate, polyphosphate, nitrite, benzoate, silicate and the like is preferably used.

The uncured resin is selected from epoxy resins, urethane resins, silicone resins, polysulfide resins, polyester resins and rubber resins. Since the water-absorbent polymer that has absorbed water is dispersed in the uncured resin, it is preferable that the uncured resin has a low viscosity and a good slump property because of its dispersibility. In addition, it is desirable that the surface of the uncured resin is coated with a dedicated primer corresponding to the uncured resin to be used.

Further, in an offshore structure, plant, or the like which is affected by waves, the body to be protected may slightly move after the protection is applied. This movement may not be able to be followed by concrete or resin whose coated anticorrosion layer has low elasticity, and cracks or peeling may occur, and further progress may cause the anticorrosion layer to fall off. Therefore, in the present invention, it is effective to use a resin having excellent elasticity such as urethane resin and silicone resin for the corrosion-prevented body under such a condition. For example, in the corrosion protection of the tidal zone part of the ocean pier foundation pile, in the tensile test of JIS A 5758,
If the elongation at maximum load is 400% or more,
The above problem does not occur. Therefore, in such a case, it is desirable to use a resin having a flexibility such that the elongation percentage is at least 100% or more.

It is desirable that the uncured resin containing the water-absorbing polymer, the oxygen absorber, etc., be protected by a protective material. As such protective material, plastic, FR
P, metal, etc. are illustrated. It is desirable to press-bond the uncured resin using such a protective material. That is, the organic material of the present invention can exert an anticorrosive effect even on a steel surface in a wet state, but in order to exert a strong adhesive force, it is necessary to perform pressure bonding with a certain constant force. This is because when the water-absorbing polymer contained in the organic material absorbs water on the surface of the steel and swells, the coating layer is pushed up, and as a result, new intrusion of water from the coated end surface is prevented. Further, when the pressure bonding is strong, the gap between the steel surface and the organic material is reduced during the pressure bonding, which means that the adhesive can be bonded more quickly, so that a favorable effect is exhibited in terms of corrosion prevention.

Further, it is desirable that the uncured resin containing the water-absorbing polymer, the oxygen absorber and the like is held by a holding material. Examples of such a holding material include a resin holding layer made of non-woven fabric, glass fiber, and flocked cloth having a uniform thickness.

Further, it is desirable that the inner surface of the above-mentioned protective material has a buffer layer against external force, and as the material forming such a buffer layer, polystyrene foam, urethane foam, soft rubber or the like can be used.

Considering that the body to be protected is exposed to a severe corrosive environment for a long period of time, when the surface of the body to be protected is in water or in a wet state, temperature changes such as summer and winter and thermal expansion and heat caused by those temperature changes. When contraction occurs, assuming that there is vibration due to wind power, hydraulic power, or other power source, for the purpose of forming a resin adhesion layer that exerts sufficient adhesive force on the surface of the anticorrosion object, in the present invention, the above An uncured resin (resin layer) containing a water-absorbent polymer, an oxygen absorber, etc. is used. Furthermore, in addition to this, the above-mentioned resin layer protective material, resin layer holding material,
A primer for improving the adhesiveness between the buffer layer of the resin layer and the resin layer is preferably used.

All the metals in the atmosphere have a water film on the surface according to the exposure environment, and the metals that corrode in the presence of water such as iron, zinc and aluminum are the water on the metal surface. Its corrosion resistance is greatly affected by the film. Therefore, when coating the surface of a metal to prevent corrosion, how to shield the metal surface from the atmospheric environment is the most important factor in preventing corrosion, as represented by painting, for example. However, it is always necessary to adhere a strong and stable coating film to the metal surface.

In the prior art, there are almost no anticorrosion methods intended for anticorrosion by adhesion, and in various practical corrosive environments, especially in water or a high humidity environment, it is not possible to adhere an anticorrosive layer to the surface of the anticorrosive body. Everything is difficult.

On the other hand, as in the present invention, when an uncured resin containing a water-absorbing polymer, an oxygen scavenger, etc. is brought into contact with the metal surface, the water on the metal surface is immediately absorbed by the water-absorbing polymer, and the metal surface remains Moisture to the extent that it hinders resin bonding is eliminated, and resin bonding is easily achieved. In addition,
Here, the curing reaction of the resin needs to be slower than the water absorption reaction of the water-absorbing polymer, and practically, it is desirable that the curing reaction of the resin be completed in 2 hours or more.

Good resin adhesion can be achieved by a similar process even on a metal surface in water, under repeated dry and wet conditions and in a high humidity environment. In particular, a feature of the present invention is that resin bonding is achieved even for an actual structure that has already been corroded or has weld beet and the like, and that is present in water. In this case, a complicated void is formed between the metal surface and the resin at the beginning of coating, but the water is immediately absorbed by the water-absorbing polymer, and the resin adheres to the metal.

[0033]

EXAMPLES The present invention will be specifically described below based on Examples and the like.

[Example 1] <Corrosion prevention effect on underwater steel material having uneven surface> Assuming the unevenness of an actual corroded steel material, a test piece having a groove with a depth of 1 mm as shown in FIG. The coating anticorrosion test was performed.

The covering material is a polyethylene plate (130 mm ×
90 mm x 3.0 ^t mm) with a non-woven fabric (polyester) having a thickness of 1.5 mm attached thereto, and 100 parts by weight of urethane-based resin absorbs the absorbent polymer (PNVA).
(System) 30 parts by weight, and 0.013 parts by weight, 0.13 parts by weight, and 1.3 parts by weight of an oxygen absorber (sodium sulfite) were impregnated with a trowel ( (Fig. 2).

The surface of the anticorrosion test piece was degreased and washed with ethanol, and then immersed in seawater at 20 ° C. in a stationary state for 48 hours for corrosion. After that, wipe off the rust on the steel surface with a cloth in seawater,
The coating material was brought into close contact with the surface in seawater, and a weight of 1 kg was placed on the polyethylene plate and left horizontally.

In order to confirm the anticorrosion state, the change with time of the polarization resistance of the anticorrosion test piece was measured. The results are shown in Table 1.

[0038]

[Table 1]

The polarization resistance and the corrosion rate are related by the following equation (for example, Metal Surface Industry Complete Document 13 Metal Corrosion Protection Technology (Revised New Edition), p. 226). I _CORR = K / Rp I _CORR : Corrosion rate K: Constant Rp: Polarization resistance

From Table 1, the oxygen absorber (sodium sulfite) was added at 1000 ppm, 10000 with the absorbent polymer.
It was found that the coated anticorrosion method of the present invention using the uncured resin (urethane-based resin) containing ppm of each exerts excellent anticorrosion performance even on a metal surface having irregularities.

[Example 2] <Corrosion protection effect on underwater steel material having an uneven surface> A test piece similar to that of Example 1 was prepared and a coating corrosion protection test according to the present invention was conducted.

The covering material is a polyethylene plate (130 mm ×
90 mm x 3.0 ^t mm) with a non-woven fabric (polyester) having a thickness of 1.5 mm attached thereto, and 100 parts by weight of urethane-based resin absorbs the absorbent polymer (PNVA).
30 parts by weight of the system) and 0.13 parts by weight of inhibitors (sodium phosphate, sodium hexametaphosphate, sodium nitrite) were added and impregnated with a trowel (FIG. 2).

The surface of the anticorrosion test piece was degreased and washed with ethanol, and then immersed in seawater at 20 ° C. in a stationary state for 48 hours for corrosion. After that, wipe off the rust on the steel surface with a cloth in seawater,
The coating material was brought into close contact with the surface in seawater, and a weight of 1 kg was placed on the polyethylene plate and left horizontally.

In order to confirm the anticorrosion state, the change with time of the polarization resistance of the anticorrosion test piece was measured. The results are shown in Table 2.

[0045]

[Table 2]

From Table 2, the coating anticorrosion method of the present invention using an uncured resin (urethane resin) containing an inhibitor (sodium phosphate, sodium hexametaphosphate, sodium nitrite) together with an absorbent polymer is uneven. It has been found that a good anticorrosion performance is exhibited even on a metal surface on which is present.

[0047]

As described above, according to the method of coating anticorrosion by the organic material of the present invention, the resin containing the water-absorbing polymer or the like is brought into close contact with the anticorrosion member in the uncured state to fix it. An extremely stable adhesive coating layer can be formed on the surface of the anticorrosion body even if the anticorrosion body is in the air, in a wet state or in water, or if the surface of the anticorrosion body has irregular irregularities such as corrosion marks. As a result, an excellent anticorrosion effect can be exhibited over a long period of time. Further, by pressing the uncured resin with the protective material, the anticorrosion effect is further exhibited.

[Brief description of drawings]

FIG. 1 is a plan view and a cross-sectional view of an anticorrosion test piece used in Examples 1 and 2.

FIG. 2 is a cross-sectional view of the covering material used in Examples 1 and 2.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tatsuya Ishii 417-16 Nakaarai, Ageo City, Saitama Prefecture Nakabo Tech Co., Ltd. Technical Development Laboratory (56) Reference JP 62-78323 (JP, A) JP 10 -323561 (JP, A) JP-A-11-19510 (JP, A) JP-A-9-176872 (JP, A) JP-A-5-9761 (JP, A) JP-A-10-324982 (JP, A ) (58) Fields surveyed (Int.Cl. ⁷ , DB name) E02D 31/06 C23F 11/00 C23F 15/00

Claims (4)

(57) [Claims] 1. A method for coating a metal surface or a concrete surface containing a reinforcing bar with an organic material, comprising: coating the metal or the reinforcing bar-containing concrete surface with an uncured resin containing a water-absorbing polymer and an oxygen scavenger.
Then, the uncured resin is pressure-bonded to the surface to remove the uncured resin.
The moisture of the surface is absorbed by the water-absorbing polymer during curing.
An anticorrosion method using an organic material. 2. The method for coating and preventing corrosion of an organic material according to claim 1, wherein the oxygen scavenger is sodium sulfite or hydrazine. 3. A coating corrosion process according organic material of the metal surface or a concrete surface comprising reinforcing bars, concrete surface comprising the metal or the rebar, coated with uncured resin comprising a water-absorbing polymer and the inhibitor, the non Of the uncured resin by pressing the cured resin onto the surface.
The moisture of the surface is absorbed by the water-absorbing polymer during curing.
An anticorrosion method using an organic material. 4. The method for coating anticorrosion with an organic material according to claim 3, wherein the inhibitor is at least one selected from orthophosphate, polyphosphate, nitrite, benzoate and silicate.