KR100642206B1 - Epoxy coating method for carbon steel plate of liner plate power plant - Google Patents

Abstract

A method for producing epoxy coating film for covering carbon steel plate faces of a housing building constructed for nuclear powder plant is provided to enhance thermal stability, to improve internal cross-linkage structure of the epoxy coating to result in increase of adhesion strength and glass transition temperature of the epoxy coating, by applying epoxy resin to both faces of the steel plate to form the epoxy coating film and emitting radiation to the epoxy coating film. The method comprises the steps of: preparing an epoxy coating film formed by applying epoxy resin to an iron face at least once; and irradiating radiation to the iron face in radiation amount of 2x10^8 to 1x10^9 and at irradiation velocity of 1x10^5 rads/h to 1x10^6 rad/h at room temperature, in order to improve adhesiveness to the iron face. The epoxy coating film is formed by the steps of: first painting the epoxy resin on the iron face then curing the painted face to form first coating film; second painting the epoxy resin on the first film and curing the coating film to form second coating film; and third painting the epoxy resin on the second film and curing the coated film to form third coating film.

Description

 Manufacturing method of steel surface epoxy coating film in containment building for nuclear power plant with improved paint performance {EPOXY COATING METHOD FOR CARBON STEEL PLATE OF LINER PLATE POWER PLANT}

1 is a schematic diagram of a design criteria accident test (DBA) device carried out in the present invention,

2 is a design criteria accident test (DBA) conditions carried out in the present invention,

3 is a graph comparing the glass transition temperature (T _g ) of the epoxy coating film according to the embodiment of the present invention compared with the prior art,

Figure 4 is a graph comparing the result of thermogravimetric analysis (TGA) according to an embodiment of the present invention compared to the prior art,

5 is a graph comparing the results of the adhesive strength of the epoxy coating film according to the embodiment of the present invention compared with the prior art.

* Short description for the drawing symbols *

1 to 6: 1 to 6 specimens

The present invention relates to a method for producing an epoxy coating film of a containment building for a nuclear power plant with improved coating performance, and more specifically, irradiation at room temperature to an epoxy coating film formed by coating an epoxy resin on at least one or more primary surfaces on both sides of the iron surface The present invention relates to a method for producing an epoxy coating film of a containment building iron surface for a nuclear power plant having improved coating performance by improving adhesion between an iron surface and an epoxy coating film.

In general, a method for producing an epoxy coating film is to use an epoxy resin on the iron surface to perform a surface pretreatment operation in order to obtain a good surface coating state, so that the coating film thickness is as thin as possible using a spray device or a spin coater. In order to prevent the coating film from occurring on the iron surface during curing, the contact with moisture is avoided as much as possible to prevent the peeling phenomenon due to corrosion of the iron surface after curing.

In addition, it is possible to maintain the adhesion of the coating state to exposure to high temperature / high pressure and long-term external stimulus by generally using inorganic powder coating in order to improve the adhesion and corrosion resistance between the epoxy resin and the iron surface of the adherend. However, the inorganic powder coating used to maintain the adhesion of the coating film has a high viscosity of the coating when used in an industrial field when compared to the epoxy resin, and due to contact with moisture, thin flaking of the adhesive surface, interlayer Delamination, peeling from the base metal surface, blistering, etc. are very likely to occur. In addition, the prior art has a disadvantage in that it is not environmentally friendly to the industrial environment. Therefore, by using the inorganic powder coating, the epoxy coating film is weak to heat and the adhesive strength and mechanical properties are reduced.

Korean Patent Laid-Open Publication No. 2004-0059977 discloses an environmentally friendly chemical conversion treatment composition for increasing the corrosion resistance and paintability of zinc and zinc alloy plated steel sheets and a steel sheet treatment method using the same. There is a problem of insufficient adhesion.

Korean Patent Laid-Open No. 2004-0071489 discloses an epoxy powder coating composition for powder fusion-type multilayer steel pipe coating and a method for coating a multilayer steel pipe using the same, but the method also does not have sufficient peeling resistance with steel pipe.

In addition, a method of coating the coating by thinning the thickness of the epoxy coating layer to about 10 nm before forming a coating film using an epoxy resin, or hydrating a metal surface before the epoxy coating is known [J. van den Brand et al., Progress in Organic Coatings, 51 (4), pages 339-350 (2004), but the process is complex.

In order to overcome the problems of the prior arts, the inventors of the present invention, by irradiation with the optimum conditions at room temperature after forming the epoxy coating, by the post-cure effect of the epoxy coating has a better adhesion to the steel surface, in particular, nuclear containment The present invention has been completed by developing a new technology that provides an epoxy coating method applicable to building steel surface coating.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a containment steel surface epoxy coating film for a nuclear power plant in which the adhesion between the metal layer and the epoxy coating film is improved without using an inorganic paint.

Another object of the present invention is to provide a method for producing a containment steel surface epoxy coating film for a nuclear power plant, which improves hydrophilicity and surface free energy of an adhesive surface, thereby improving the excellent mechanical properties and durability of the epoxy resin coating film.

In order to achieve the object as described above, the containment building steel surface epoxy coating method for a nuclear power plant of the present invention is irradiated at room temperature to the epoxy coating film formed by coating an epoxy-based resin to the iron surface at least one or more iron surface It is characterized by improving the adhesiveness with.

In the present invention, the irradiation is preferably carried out at a radiation dose of 2 × 10 ⁸ ~ 1 × 10 ⁹ rads and irradiation speed of 1 × 10 ⁵ rads / h to 1 × 10 ⁶ rads / h.

It is preferable to add a design criterion accident test (DBA) to the epoxy coating.

In the present invention, the epoxy coating is cured after primary coating of an epoxy resin on the iron surface, to prepare a primary coating, and after curing secondary coating with an epoxy resin on the primary coating, the secondary coating It is preferable to manufacture, after carrying out tertiary coating with an epoxy resin on the said secondary coating film, and to make a tertiary coating film.

It is preferable to pretreat the iron surface for 1 to 10 minutes by sandblasting or grinding before performing the primary coating.

It is preferable that the said epoxy coating film is formed in 150-300 micrometers of coating film thickness.

Curing after the epoxy coating is preferably carried out for 5 to 14 days.

The epoxy coating film formed according to the method of the present invention preferably has an initial pyrolysis temperature of 200 to 390 ° C. and an adhesive strength of 90 to 150 MPa.

Hereinafter, the present invention will be described in detail.

The present invention provides a method for producing an epoxy coating film having improved adhesion to the iron surface by irradiating at room temperature to the epoxy coating film formed by coating an epoxy-based resin on at least one or more primary sides of the iron surface.

In this case, the irradiation is carried out at a radiation dose of 2 × 10 ⁸ rads ~ 1 × 10 ⁹ rads and irradiation speed of 1 × 10 ⁵ rads / h to 1 × 10 ⁶ rads / h.

If the irradiation amount is less than 2 × 10 ⁸ rads, it is not preferable to the nuclear steel containment building test standards, while if it is irradiated more than 1 × 10 ⁹ rads, the problem of cracks in the test specimen due to excessive irradiation Is generated.

The irradiation when the speed is 1 × 10 ⁵ performed in rads / less than h, when carried out is not preferable to the test requirements applicable to a nuclear power plant containment steel surface dojangjae exceeds 1 × 10 ⁶ rads / h, unit of excessive per hour Irradiation is not preferred for the specimen coating state. At this time, the most preferable coating film state was shown when the radiation dose was performed at 4 × 10 ⁵ to 5 × 10 ⁵ rads / h.

The manufacturing method of the present invention is preferably performed by adding a design standard accident test (DBA) to the epoxy coating film.

Figure 1 shows the internal schematic diagram of the device for the design reference accident test (DBA), the epoxy coating was tested by generating a turbulence (Turbulence) inside the design reference accident (DBA) test apparatus.

Figure 2 shows the test conditions of the design standard accident test (DBA), the test is an essential test procedure required for the steel surface coating specifications of the nuclear power plant containment building, the design standard accident test (DBA) in the present invention Is the nuclear power standard ANSI N101.2 / CP-A3 Spec. No. Implementation is based on 9-191-A610 / A291.

More specifically, the nuclear-related standards are ASTM D 3911, ANSI N 101.2, ASTM D 772, ASTM D 714 Check the integrity of the radiation-resistant coating performance on the liner plate steel surface in the containment building (RCB) nuclear power plant Design Base Accident Test (DBA) for the test items. In addition, by performing the design standard accident test (DBA), the adhesive strength, radiation resistance, post-curing function which is soundness to the radiation-resistant coating performance of the epoxy coating film of the present invention is given.

The epoxy coating film may be formed by coating an epoxy-based resin at least a primary or more on the iron surface, and more specifically, as an example of the preferred epoxy coating film of the present invention, the epoxy resin on the front, rear and all corners of the iron surface. After primary coating to cure to prepare a preliminary specimen, secondary coating with epoxy resin on at least one surface of the preliminary specimen and curing to produce a specimen, the front, back and all corners of the specimen with an epoxy resin It is prepared by curing after the third coating.

It is prepared by pre-treating the iron surface for 1 to 10 minutes by the sand blasting method or the grinding method before performing the primary coating.

The said epoxy coating film is formed in 150-200 micrometers of coating film thickness of a front surface, and 200-300 micrometers of coating film thickness of a back surface.

When curing after the epoxy coating, it is preferably carried out for 5 to 14 days.

At this time, if the curing time after the epoxy coating is less than the above period, the complete curing does not proceed, the coating film is unstable, and if the period is long, the coating film properties such as water infiltration due to the change of external conditions (peel phenomenon) occurs.

Prepared by the above method, the initial pyrolysis temperature is 200 ~ 390 ℃, the adhesive strength is to be 90 ~ 150 MPa.

Figure 3 is a comparison of the glass transition temperature (Glass transition temperature) of the epoxy coating film according to an embodiment of the present invention compared to the prior art, Example 2, Example 4 and Example 5 is irradiated and / or design While the glass transition temperature was increased due to the increase in the crosslinking density and the post-curing effect of the epoxy coating film according to the standard accident test (DBA), the case of Comparative Example 1 did not show the above results and showed a relatively low glass transition temperature value. The result was confirmed. In particular, the glass transition temperature of Example 5 subjected to irradiation and design criteria accident test (DBA) was the largest.

Figure 4 compares the thermal stability of the epoxy coating film according to an embodiment of the present invention as compared to the prior art, Example 2, Example 4 and Example 5 showed a result of increasing the value of the thermal stability parameter, the comparison In the case of Example 1, relatively low thermal properties were confirmed.

5 is a comparison of the epoxy coating film adhesive strength according to the embodiment of the present invention in comparison with the prior art, Example 2, Example 4 and Example 5 showed a result of increasing the adhesive strength value Comparative Example 1 In the case of relatively low adhesion strength results were confirmed.

In the following, embodiments of the present invention will be described. However, the following examples are only intended to illustrate the invention and should not be construed as limiting the scope of the invention.

< Example  1>

Using the conventional epoxy material and the iron surface, the primary, secondary and tertiary coating films were formed on the front, back and front corners, and then cured and irradiated. The epoxy material is a resin that is actually applied to a nuclear power plant CLP, used as a curing agent, and used as an epoxy primer (ET 5290) made of a polyamide component and a two-component resin manufactured by KCC. . The steel surface was a white blast-cleaned carbon steel (ASTM A36) having a size of 50 mm in width, 100 mm in length, 3 mm in height and a hole of 6 mm in diameter at the top. In order to obtain a good coating adhesion with the iron surface during the epoxy coating, sand blasting was performed with steel balls on the steel surface 2 hours before the painting operation. After pretreatment (SSPC SP10 / near white blast cleaning) for 5 minutes per specimen, the coating was carried out using an air spray method with an epoxy paint. In order to obtain good coating adhesive strength, the epoxy coating film may be formed of a tertiary or higher coating film, and the pretreatment time may be changed to 1 to 10 minutes.

In the case of the primary coating, 14 days after curing the air before the front / back and the edge (edge) of the specimen was cured. In the case of the secondary coating film, only the back side of the specimen was ground (grinding-dia.:1/2 "), then touched up with epoxy paint and cured again for 14 days. After the final coating of the front / rear and all edges of the specimens with epoxy resin, the specimens were cured for 14 days, and the final test specimens were made as thin as possible. In order to prevent the coating from occurring during curing for 14 days, the temperature and humidity were adjusted to remove the contact of moisture as much as possible, and the curing time and the thickness of the coating can be adjusted to improve the characteristics of the coating. It can be painted in succession more than the difference, the curing time can be changed from 5 days to 14 days, and the thickness of the film can be adjusted at the front, back and all corners In order to increase the contact strength according to the surrounding environment, the front side may be changed to 150 to 200 μm and the rear side to 200 to 300 μm.

In addition, the glass transition temperature, thermogravimetric analysis (TGA) and adhesion strength, which are thermal properties of the epoxy resin / carbon steel A 32 specimen, were tested. The results are shown in Figures 3, 4, 5.

As a surface treatment method for improving the adhesion of the epoxy resin / carbon steel A 32 specimens, the irradiation was tested with a total radiation dose of 2 × 10 ⁸ rads, irradiation rate 1 × 10 ⁵ rads / h per hour.

< Example  2>

The epoxy resin / carbon steel A 32 specimen prepared in the same manner as in Example 1 was irradiated. The total radiation dose was 2 × 10 ⁸ rads, and the irradiation speed was 5 × 10 ⁵ rads / h per hour, and the results are shown in FIGS. 3, 4 and 5.

< Example  3>

The epoxy resin / carbon steel A 32 specimen prepared in the same manner as in Example 1 was irradiated. The total radiation dose was 2 × 10 ⁸ rads, and the irradiation speed was 1 × 10 ⁶ rads / h per hour.

< Example  4>

The epoxy resin / carbon steel A 32 specimens prepared in the same manner as in Example 1 were subjected to only design criterion accident test (DBA) without irradiation. The design criterion accident test (DBA) was in accordance with ANSI-N101.2-72 and ASTM D3911-95 (Figure 2), and the results are shown in Figures 3, 4 and 5.

< Example  5>

After the irradiation to the epoxy resin / carbon steel A 32 specimen prepared in the same manner as in Example 1 was subjected to the design standard accident test (DBA). The radiation was 2 × 10 ⁸ rads, the irradiation speed was 1 × 10 ⁶ rads / h per hour, and the design standard accident test (DBA) was conducted in accordance with ANSI-N101.2-72 and ASTM D3911-95. 2) and the results are shown in FIGS. 3, 4 and 5.

< Comparative example >

Irradiation and design criteria accident tests (DBA) were not performed on the epoxy resin / carbon steel A 32 specimens prepared in the same manner as in Example 1. The results are shown in FIGS. 3, 4 and 5.

In the present invention, each characteristic value was measured by the following method.

< Experimental Example  1> Thermal analysis  exam

The thermal analysis test is a test for measuring the activation energy thermal stability of the primary abnormal coating film. Perkin Elmer's DSC-6 instrument was used for the thermal analysis of the curing reaction of epoxy resin / carbon steel A 32 specimens and the activation energy of the cured product. Dynamic differential scanning calorimetry (DSC) heating rate is 2 ℃ · min ^-1 , 5 ℃ · min ^-1 , 10 ℃ · min ^-1 and 20 ℃ · to obtain the activation energy according to the Kissinger equation. min- ¹ . In addition, a thermogravimetric analyzer (dupont, TGA-2950) was used to measure the thermal stability of the epoxy coating film, the temperature at the maximum pyrolysis rate (Ts), pyrolysis activation energy (decomposed activation energy), integral pyrolysis progress temperature ( IPDT (integral procedural decomposition temperature) and the like were measured. Thermogravimetric analysis (TGA) experimental conditions using the thermogravimetric analyzer (dupont, TGA-2950) were tested under a temperature range of 30 to 850 ° C., a temperature increase rate of 10 ° C. min ^−1, and nitrogen (N ₂ ). The results are shown in Table 1.

< Experimental Example  2> Design Standard Accident Test DBA )

The Design Criteria Accident Test (DBA) was tested in accordance with ANSI-N101.2-72 and ASTM D3911-95, which are all test methods and test standards for radiation-resistant coatings of nuclear facilities in pressurized water reactors. (Fig. 1) The total extension test time according to the test method and test standard is the sum of 1 million seconds, which is an essential time for the test requirements, and a lag time for reaching a steady state, and the maximum temperature and pressure are 302 ° F. and 54 psig, respectively. (FIG. 2).

< Experimental Example  3> Adhesion strength measurement

The adhesive strength of the epoxy resin / carbon steel A 32 specimen according to the water immersion treatment was an epoxy adhesive according to ASTM D 4541-95 of the Design Standard Accident Test (DBA). The test was conducted using a universal testing machine (Universal Testing Machine, Lloyd LR5K) in the tensile state, the average value was measured five times by a pull-off (pull-off) adhesion test. As the epoxy adhesive, DGEBA (diglycidylether, Kukdo Chemical Co., Ltd., YD-128, EEW = 185 ~ 190 g / mol, density 1.16g / cm3) of bisphenol A, a bifunctional epoxy oligomer, was used. DDM (4,4-diamino diphenyl methane) was used. An adhesive strength test was carried out with a test piece prepared through the following examples, and the adhesive strength was measured to be 90 to 150 MPa.

Table 1 below is an experimental result table according to the test method and the embodiment, Curing activation energy (Initial decomposition temperature) (IDT), temperature at the maximum weight reduction (T _{max ;} temperature of maximum Experiments on rate of weight loss, thermal stability index (A ^* × K ^* ), integral procedural decomposition temperature (IPDT), and decomposed activation energy (Decomposed activation energy). The curing activation energy indicates a measure of the crosslinking reaction for the polymer material forming the three-dimensional crosslinked structure. When the activation energy value is increased, the energy required to cure the polymer material is large. In addition, the thermal decomposition activation energy is an energy value required when the molecular bond is decomposed by external energy such as heat of the polymer material forming the three-dimensional crosslinked structure.

The initial decomposition temperature (IDT) represents the temperature at which thermal decomposition of the material is started, and the temperature of maximum rate of weight loss (Tmax) is the maximum weight loss of the material due to thermal decomposition. The thermal stability index (A ^* × K ^* ) and the integral procedural decomposition temperature (IPDT) are quantitative values obtained from the area ratio of the TGA thermal analysis diagram. It provides useful information that is very reproducible, and a large value indicates excellent thermal stability.

TABLE 1

Table of Experiment Results According to Examples

Test piece Cure activation energy (E _a , kJ / mol) IDT (℃) T _max (℃) A ^* × K ^* IPDT (℃) Decomposed activation energy (E _t , kJ / mol) Example 1 140 280 399 4.86 3760 84 Example 2 142 281 399 4.87 3780 83 Example 3 143 279 400 4.85 3760 80 Example 4 159 382 411 4.99 4032 88 Example 5 141 290 383 4.90 3880 86 Comparative example 147 380 405 4.97 4016 85

In Example 5, the uncured portion of the irradiated epoxy resin / carbon steel A 32 specimen was simultaneously irradiated with a design standard accident test (DBA). Since the active area by post-curing and radical can form a more dense hardening network, the said epoxy coating film has a favorable influence on the characteristic of an epoxy coating film.

In addition, the adhesion strength between the epoxy resin and the metal was increased according to the design standard accident test (DBA) in Examples 4 and 5, and the result was the interface between the polymer and the metal due to the high temperature pressurization of the epoxy system after curing. Wetability to other materials is improved by increasing the surface free energy due to the development of oxygen-containing functional groups.

In addition, the surface of the test piece increases the adhesive strength because the active functional groups introduced by the test form a covalent bond with the epoxy ring (C-C-O) or hydroxyl group (-OH group) of the adhesive.

At this time, the case of the test piece including the design reference accident test (DBA) of Example 4 and Example 5 shows a higher adhesive strength compared with the case where only the irradiation process of Examples 1-3 was performed. This is because post-curing of the epoxy resin occurs as the temperature and pressure are applied, and the adhesive strength is improved as the development factor of the curing network forming factor of the test piece is increased.

As we saw above,

First, the present invention improves the curing and crosslinking degree of the coating film due to the radiation treatment for strengthening the adhesion between the iron surface and the epoxy resin when forming a coating film using an epoxy resin that is difficult to bond to metal and stone due to low surface energy, etc. Therefore, it is easy to use, has a large area, excellent effects can be obtained in a short time, and there is an effect of improving the adhesive strength.

Second, there is an effect of improving the adhesive strength by providing hydrophilicity and water repellency, post-cure and crosslinking degree to organic and inorganic polymers, carbon materials and other metals and stones.

Third, the present invention has an effect that can be applied to various industrial fields that require high reliability and stability in addition to the protective coating system for the nuclear power plant to improve the adhesion to the steel surface, the degree of crosslinking is improved.

In conclusion, the present invention improves the internal crosslinking structure in the cured epoxy coating system, thereby increasing the glass transition temperature (T _g ) and the adhesion strength (adhesion strength) and improving the thermal stability. Due to the increase, the adhesive strength and mechanical properties of the entire system are increased.

Although the present invention has been described in detail only with respect to the embodiments described, it will be apparent to those skilled in the art that various modifications and variations are possible within the technical spirit of the present invention, and such modifications and variations belong to the appended claims. .

Claims (8)

On the epoxy coating film formed by coating an epoxy-based resin on at least a primary By irradiating radiation at room temperature with radiation dose of 2 × 10 ⁸ to 1 × 10 ⁹ rads and irradiation speed of 1 × 10 ⁵ rads / h to 1 × 10 ⁶ rads / h The manufacturing method of the epoxy coating film characterized by improving the adhesiveness with the said iron surface. delete The method according to claim 1, wherein a design reference accident test is performed on the epoxy coating film. The method of claim 1, wherein the epoxy coating is cured after primary coating the epoxy resin on the iron surface, to prepare a primary coating film, After secondary coating with an epoxy resin on the primary coating film and curing, to prepare a secondary coating film, The secondary coating film is cured with an epoxy resin after tertiary coating and cured to produce a tertiary coating film. 5. The sandblasting method according to claim 4, wherein the sandblasting method or grinding room is performed before the first painting is performed. Method for producing the epoxy coating film characterized in that the iron surface is pretreated for 1 to 10 minutes. The method for producing the epoxy coating film as claimed in claim 4, wherein the epoxy coating film has a thickness of 150 to 300 µm. The method of claim 4, wherein the curing is carried out for 5 to 14 days after curing after the epoxy coating. The epoxy coating film prepared by the method of claim 1 has an initial pyrolysis temperature of 200 to 390 ° C., and an adhesive strength of 90 to 150 MPa.

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