JP2607660B2 - Conductive paint film for seawater electrolysis - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a conductive paint film for seawater electrolysis, for example, anticorrosion in a seawater submerged portion of a hull outer panel or an offshore structure, a seawater intake portion of a power plant, and the like. The present invention relates to the paint film applied as a coating film or the like.

[Prior Art] A conventional conductive paint film for seawater electrolysis is, as shown in FIG.
Is formed, and an electro-durable type top-coating conductive paint film 05 is applied thereon.

The resin and the solvent in the overcoating conductive paint film 05 dissolve and dissolve on the surface of the undercoating conductive paint film 03 to form an overall paint film, which is used for seawater electrolysis.

That is, when the outer shell of the hull, for example, on which the paint film is formed is submerged in seawater, the seawater is electrolyzed on the surface of the overcoating conductive paint film 05 to generate chlorine ions, and the chlorine ions cause microorganisms in the seawater. Can be prevented from adhering to the hull outer panel and the like, and as a result, corrosion prevention of the hull outer panel and the like can be achieved.

[Problems to be Solved by the Invention] By the way, in a conductive paint using a metallic conductive filler, an acrylic resin is used as a binder of the conductive filler, and copper powder or nickel powder is used as the conductive filler. As a solvent, xylene is used from the viewpoint of workability.

In the case of a conductive paint film for seawater electrolysis, the paint film alone consisting of the above-mentioned metal filler, binder, and solvent dissolves the metal filler in seawater and does not use it. An overcoating conductive paint film 05 of the mold is formed.

The top-coating conductive paint film 05 differs from the undercoating conductive paint film 03 in the type of conductive filler, and has a specific resistance higher than that of the undercoating conductive paint film 03 by three digits or more.

As described above, since the specific resistance value of the top-coating conductive paint film 05 is high (that is, the conductivity is low), this top-coating conductive paint film 05
When 05 is compatible with the undercoating conductive paint film 03, the conductivity of the undercoating conductive paint film 03 is reduced, and the practicality as a conductive coating film for seawater electrolysis is lost.

In addition, a conductive paint of an acrylic resin using a commercially available metal filler is dried slowly, and when this is used as an undercoat conductive paint, an overcoat conductive paint is applied on the undercoat conductive paint film 03 that is not sufficiently dried. This often occurs, and when the overcoating conductive paint is applied, the undercoating conductive paint film 03 and the overcoating conductive paint are compatible with each other, and the conductivity of the undercoating conductive paint film 03 is reduced.

This tendency is most affected by the temperature at the time of painting, and the tendency becomes larger as the temperature decreases.

The present invention solves such a problem, has high practicality,
An object of the present invention is to provide a conductive paint film for seawater electrolysis having excellent durability.

[Means for Solving the Problems] The present invention provides the above-mentioned object for the purpose of generating chloride ions by seawater electrolysis, wherein the undercoating conductive coating film is a two-component curable urethane. , Two-part curable epoxy, acrylic, or vinyl resin, and contains 25-40% by volume of copper, nickel, or silver in the film, and has a specific resistance of conductivity. Ten
^This is achieved by a conductive paint film for seawater electrolysis, which is characterized by having a ^-1 to 10 ^-4 Ω-cm.

Further, in the present invention, an intermediate conductive paint film may be provided between the undercoat conductive paint film and the top conductive paint film.

[Function] In the present invention, a two-component curable urethane-based resin or epoxy-based resin is used as the undercoating conductive paint film, and drying is promoted by a polymerization reaction between the main agent and the curing agent.

In the present invention, an acrylic resin or a vinyl resin is used as the undercoat conductive paint film in addition to the above resin.

And, as a solvent for these resins, a conventional acrylic resin,
Instead of xylene which is a vinyl resin solvent, toluene, ethylbenzene, n-octane, methylcyclohexane, diethylketone, methyl / n-propylketone,
Methyl isobutyl ketone or the like is used alone or in combination. Since the vapor pressure of these solvents is higher than the vapor pressure of xylene, drying is promoted.

Further, in the present invention, in order to secure the conductivity of the undercoat paint film, copper, nickel or silver is contained as a conductive filler in a paint comprising at least one of the above resins. In particular, copper is preferable in consideration of conductivity, cost, and the like.

The reason why the content of copper, nickel or silver is set to 25 to 40% by volume is as follows. If it is less than 25% by volume, the undercoating conductive paint film cannot have the desired conductivity.
Conversely, if it is more than 40% by volume, the amount of the resin acting as a binder for the filler becomes relatively small, and the desired film strength cannot be obtained, the durability becomes poor, and the number of pores increases. In addition, the resistance at the time of recoating increases.

Further, the conductivity of the undercoat paint film is expressed as a specific resistance value of 10 ^-1 to 10 ^-4.
Although it is preferable that the specific resistance value is as small as Ω-cm, the coating film cannot be reduced to 10 ^-4 Ω-cm or less, and 10 ^-1
If it is larger than Ω-cm, it will not function as an undercoat paint film for the conductive paint film for seawater electrolysis.

The above-described range of the specific resistance value is ensured even in the conventional undercoat conductive paint film.

The undercoating conductive paint film must have a dry film thickness of at least 100 μm for practical use. The upper limit of the film thickness depends on the resistance value (smaller as the thickness increases), drying time, cost, film strength, and the like, and cannot be unconditionally determined, but is practically 1 mm or less. The relationship between the specific resistance and the film thickness is as follows: It is represented by the following equation. Here, R is the resistance value of the paint film, ρ is the specific resistance value, L is the length of the paint film, W is the width of the paint film, and D is the thickness of the paint film.

Further, in the present invention, an intermediate coating film that is incompatible with the solvent and the resin of the top coating may be formed between the undercoat conductive coating film and the top coating conductive coating film.

That is, the intermediate coating film is formed by applying the above-mentioned undercoating conductive coating film and an overcoating conductive coating film (10 ^-2 to 10 ² Ω-cm) having an action of electrolyzing seawater in seawater. And a barrier film that functions to prevent the lowering of the conductivity due to the compatibility of the upper coating with the top coating.

As the intermediate coating, a polymer coating having a three-dimensional molecular structure that is resistant to the solvent (eg, xylene) of the above-described conductive coating and the resin (eg, a vinyl resin) of the conductive coating must be selected. In the present invention, it is preferable to use a two-component curable urethane resin, a two-component curable epoxy resin, or an unsaturated polyester resin.

The intermediate coating film having the three-dimensional molecular structure does not become compatible with the upper coating film even when the upper coating film is coated thereon, and the intermediate coating film is not formed between the lower and upper coating films. , The adverse effect of the top coat on the undercoat paint film is eliminated, and therefore the conductivity of the undercoat paint film is not reduced.

Further, it is desirable that a carbon-based conductive filler is mixed into the intermediate coating conductive coating film, preferably in an amount of 30 to 60% by volume, and the conductivity is set to a specific resistance of 10 ^-1 to 10 ² Ω-cm.

[Examples] Table 1 shows that three-component compositions of a, b, and c were prepared by using a two-component curable urethane-based resin as the resin for the undercoating conductive coating film and varying the amount of copper. This shows the effect of the coating film (thickness: 200 μm) obtained from these paints on the conductivity and the drying property.

In Table 1, the two-component curable urethane-based resin is made into a paint by blending a base polyol and a curing agent isocyanate (Desmodur L), and the copper powder is a product manufactured by Fukuda Metal Foil Powder Co., Ltd. The name FCC-155A was used.

Table 2 shows that three types of d, e, and f undercoats were prepared in the same manner as in Table 1 except that a two-part curable epoxy resin was used as the resin for the undercoat conductive film. However, it shows the effect on the conductivity and the drying property of the coating films obtained from these paints.

In Table 2, the two-part effect type epoxy resin used was Epicoat 1001 (trade name, manufactured by Shell Chemical Co., Ltd.), and was blended with a polyamide resin (Versamide 115, trade name, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) Then, the same copper powder as in Table 1 was used.

Table 3 shows g, h, and g in the same manner as in Table 1 except that an acrylic resin was used as the resin for the undercoat conductive film.
The undercoat paints of four compositions of i and j were prepared, and the effect on the conductivity and the drying property of the membrane obtained from these paints was shown.

In Table 3, the solvent C was a mixed solvent of xylene and methyl isobutyl ketone, the solvent D was a mixed solvent of toluene and methyl isobutyl ketone, and the same copper powder as in Table 1 was used.

In Tables 1 to 3, similar results can be obtained by using nickel or silver instead of copper.

Also, in Table 3, the same results as in Table 3 can be obtained by using a vinyl resin instead of an acrylic resin.

FIG. 3 is a diagram showing the results of Tables 1 to 3, wherein the volume pigment concentration PVC (%) on the horizontal axis indicates the volume% of copper in the (dried) coating film.

In addition, in Tables 1-3, all paints contain 1% or less of paint property adjusting additives (polyethylene wax as a thixotropic agent).

FIG. 1 is a view showing an example of the configuration of a conductive coating film for seawater electrolysis according to the present invention, wherein an anticorrosion coating (insulating coating) 2 on a hull outer panel 1 is shown.
Then, the undercoat paint film 3 shown in Tables 1 to 3 is applied with a thickness of 200 μm, the intermediate coat conductive paint film 4 is applied thereon with a thickness of 10 to 150 μm, and the top coat conductive paint film 5 is applied with a thickness of 300 μm. It is painted.

The intermediate coating conductive coating film 3 was composed of 53.2 g of a two-part curable urethane resin containing a base poly and a hardener isocyanate (Desmodur L) (base: hardener = 8.3: 2.5 weight ratio), High-purity graphite powder with an average particle size of 45 μm and a particle size distribution of 20 to 100 μm, and an average particle size of 2 μm and a particle size distribution of 0.5 to 30 μm
(A specific resistance value of the dried coating film is 0.05 Ω-cm compared with the resistance of the undercoating conductive coating film 3 alone (initial electric resistance)). Met).

[Effects of the Invention] As is apparent from Tables 1 to 3, the undercoating conductive coating film of the present invention is a coating on the undercoating conductive coating film after the application of the undercoating coating, that is, an overcoating conductive coating or an intermediate coating conductive coating. The drying period before painting is short.

Therefore, the undercoating conductive paint film is completely dried before the topcoating or intermediate coating paint application, and the undercoating conductive coating film does not become compatible with the paint applied thereon.

As a result, the conductivity of the undercoat conductive paint film does not decrease.

Although a dry paint film having a specific resistance of 10 ^-3 to 10 ^-4 (Ω-cm) is practical as a paint film for seawater electrolysis, if it is not particular about the efficiency of chlorine ions generated during electrolysis,
Any of the compositions shown in Tables 1 to 3 can be used satisfactorily.

In particular, when the film of the present invention is used as an anticorrosion paint film for a hull outer panel, it is sufficient that chlorine ions are generated to such an extent that microorganisms in seawater are not attracted. Can be used well.

Further, when the intermediate coating conductive coating film is provided on the undercoating conductive coating film, the intermediate coating conductive coating film acts as a barrier film to prevent compatibility between the undercoating conductive coating film and the upper coating conductive coating film. Thus, it is possible to more effectively prevent the conductivity of the undercoating conductive paint film from lowering.

[Brief description of the drawings]

FIG. 1 is a view showing one configuration example of the film of the present invention, FIG. 2 is a view showing a conventional conductive paint film for seawater electrolysis, and FIG. 3 is a diagram showing the copper content and specific resistance in the undercoat conductive paint film of the present invention. It is a figure showing the relation with a value.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kenji Ueda 1-1, Akunouracho, Nagasaki-shi, Nagasaki Prefecture Mitsubishi Heavy Industries, Ltd. Nagasaki Research Laboratory (72) Inventor Kiyomi Tomoshige 1-1, Akunouracho, Nagasaki-shi, Nagasaki Prefecture (72) Inventor Shozo Ota 5-7 Akunoura-cho, Nagasaki City, Nagasaki Prefecture, Ryoko Building Annex Building 5th Floor, Nagaishi Engineering Co., Ltd. (72) Inventor Tsutomu Horiguchi, Tsutomu Horiguchi Atsunoura, Nagasaki City, Nagasaki Prefecture 5-7 Ryocho Building Ryoko Building Annex 5F Nagaishi Engineering Co., Ltd.

Claims (2)

(57) [Claims] 1. A conductive paint film provided for the purpose of generating chlorine ions by seawater electrolysis and comprising an undercoat and an overcoat, wherein the undercoat conductive paint film is a two-part curable urethane-based, two-part curable epoxy-based, acrylic, vinyl, Any one of the resin of the system
Of copper, nickel or silver in the film.
~ 40% by volume, conductivity is specific resistance 10 ^-1 ~ 10 ^-4 Ω-cm
A conductive paint film for seawater electrolysis, characterized in that: 2. The conductive paint film for seawater electrolysis according to claim 1, wherein an intermediate paint film is provided between the undercoat paint film and the top paint film.