JP2007314763A - Edge cover coating and method for forming thick film coating to steel edge using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a means for effectively forming a thick film coating in order to improve the corrosion preventability of the edge of a magnetic metal substrate, in particular, sharp edges of steel which is formed by mechanically cutting. <P>SOLUTION: The thick film can be formed in the edge using the edge cover coating containing magnetic substance powder in the solid content at prescribed ratio (3-40 wt.%), locating the coated material such as steel material in magnetic field when applying the coating, or after applying the coating and before the coating is hardened (loses flowability), and using magnetic characteristic differences between the edge and a planar part close to the edge. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to coating of steel materials having edges. More specifically, the present invention relates to a coating material for forming a coating film having a sufficient film thickness on an edge of a steel material or the like on an anticorrosive action and the like, and a thick film coating film forming method using the coating material.

  An anticorrosion paint is often applied to the surface of a steel plate used for a steel structure such as a new ship for the purpose of preventing rusting. However, the edge of the steel plate, particularly the sharp edge that has been mechanically cut, is sharp, and it is difficult for the paint to be applied to these coated portions, so that rust is first generated from this portion. Conventionally, in order to ensure a sufficient film thickness on the edge of such a steel plate for anti-corrosion effects, a touch-up after forming a thin film part (edge treatment) with a grinder or the like prior to coating or forming a thin film part A step of recoating by (repair coating) is performed. In recent years, shortening of the shipbuilding process has been desired, and means for shortening or eliminating these processes have been studied in various fields. However, in addition to the above edge treatment, a thick film is applied to the edge at present. There is no effective means.

  In addition, the coating material containing magnetic substance powder or the method of apply | coating it in a magnetic field can be seen also in the invention so far. For example, Japanese Patent Laid-Open No. 5-255617 (Patent Document 1) discloses a paint containing a flaky pigment made of a magnetic material or a flaky pigment having a thin layer made of a magnetic material substantially parallel to its flat plane. It is described that a coating film having an excellent anticorrosive effect due to the labyrinth effect can be formed by applying the coating in a magnetic field substantially perpendicular to the coating surface of a metal member such as stainless steel. In JP-A-7-90203 (Patent Document 2), as a method for forming a magnetic coating film, which is a track for guiding a carriage, on a steel sheet, a paint in which a powdered magnetic material (ferrite powder) is blended with a resin paint It is described that magnetizing is performed after coating. In JP-A-7-330948 (Patent Document 3), an external magnetic field is used in the production of a coating film or molded body using a resin composition containing a scaly iron oxide-based gloss content having a hematite structure. It is described that the color tone of the resulting coating film or molded product changes when applied.

However, the inventions described in these patent documents are not intended to form a thick film coating on a steel material edge, and that a thick film coating can be formed on a steel material edge. There is no suggestion.
JP-A-5-255617 JP-A-7-90203 JP-A-7-330948

  The present invention provides a paint capable of efficiently forming a thick film coating on a free edge that is not subjected to a grinder treatment or the like, such as a steel material, and a coating method using the paint. With the goal.

  The present inventor uses an edge cover paint obtained by mixing magnetic powder with a conventional paint, and before or after the application of the paint, the paint is solidified (loses fluidity). In addition, it is found that a thick film can be formed on the edge by using the difference in magnetization characteristics between the edge and a plane portion in the vicinity thereof by placing the steel material coating in a magnetic field, and the present invention is completed. It came to.

  The edge cover paint according to the present invention is characterized by containing 3 to 40% by weight of magnetic powder in the solid content of the paint. The magnetic powder is preferably made of magnetite, ferrite, or a mixture thereof.

  The edge cover paint according to the present invention is particularly preferably used as an anticorrosion paint for steel. Therefore, it is preferable to contain an alkyd resin, a chlorinated rubber, a vinyl resin, an acrylic resin, an epoxy resin, a urethane resin, a polyester resin, a vinyl ester resin, or an inorganic resin in addition to the magnetic powder.

  The method for forming a thick film coating on the steel material edge according to the present invention is a step of applying the edge cover paint according to the present invention to the steel material edge in a magnetic field, or the edge cover paint according to the present invention is applied to the steel material edge. It is characterized by including the process of leaving still in a magnetic field later, or both of these processes. It is preferable that the surface magnetic flux density of the steel material edge by a magnetic field is 5 millitesla (mT) or more.

  By the edge cover paint according to the present invention and the thick film coating method using the same, a film having a sufficient film thickness is formed on the edge of a steel material or the like in a ship, an underwater / water structure and a land structure. can do.

  According to the present invention, a sufficient film thickness is ensured even at the free edge of the steel material, and the formation of a thin film can be suppressed, so that the conventional edge processing can be reduced or omitted, and the number of touch-ups can be reduced. It leads to shortening of the process period.

  Hereinafter, various components such as magnetic powder, resin, and pigment contained in the edge cover paint, the content of the magnetic powder, and a method of forming a coating film made of this edge cover paint on the steel edge using a magnetic field These will be described sequentially.

Edge Cover Paint The “edge cover paint” according to the present invention is a composition comprising magnetic substance powder and various components contained in a known paint, in other words, a known paint (hereinafter referred to as “base paint”). ) Is a coating material in which a magnetic powder is further added, which can form a sufficient thick film on the edge of a steel material or the like by using a magnetic field. In the present invention, it is preferable that the base paint is a paint that is used in a form that is typically applied directly to a metal base material of steel as an undercoat, typified by an anticorrosion paint.

  It should be noted that the components and preferred embodiments of the base paint can be appropriately selected and adjusted by those skilled in the art, and can be used in the edge cover paint of the present invention in combination with the magnetic powder. It is not limited at all.

<Magnetic powder>
The “magnetic powder” is a powder of a metal (magnetic material) that is magnetic in a magnetic field, represented by an iron oxide-based substance, and various known magnetic powders can be used in the present invention. For example, magnetic powder composed of magnetite (Fe ₃ O ₄ ) or ferrite (MO · 6Fe ₂ O ₃ : M represents a divalent ion of a metal such as Sr, Ba, Co, Ni, Mg, Cu, etc.) Alternatively, these mixtures are suitable because they are easily available, have a strong saturation magnetization, and have little residual magnetization. The magnetite is also known as a black pigment.

Magnetic powders such as those mentioned above are on the market. For example, the trade name “Todacolor KN-320” (manufactured by Toda Kogyo Co., Ltd.), “TAROX BL-100” (manufactured by Titanium Kogyo Co., Ltd.), etc. It can also be used in the present invention.

  In the edge cover paint of the present invention, the magnetic powder is blended at a predetermined ratio in the solid content in the paint (a component that forms a cured coating film, excluding volatile components such as a solvent, also referred to as a non-volatile content). It is desirable that From the viewpoint of workability in the coating process and adhesion to the edge in a magnetic field as described later, the content of the magnetic substance powder in the solid content of the edge cover paint is preferably 3 to 40% by weight. -30% by weight is more preferred. The content of such a magnetic powder can be appropriately adjusted within the above range according to the viscosity of the edge cover paint and the magnetic field to be applied.

<Resin composition>
In the present invention, since the properties of the base paint described above are basically inherited by the edge cover paint, a suitable base paint is selected according to the use of the edge cover paint, and the components of the resin composition contained therein are selected. What is necessary is just to mix | blend with an edge cover coating material.

  For example, the edge cover paint of the present invention can be suitably used as a paint for an anticorrosion paint by blending a resin composition used for the anticorrosion paint. Such resin compositions include alkyd resins, chlorinated rubber, vinyl resins, acrylic resins, epoxy resins, urethane resins, polyester resins, vinyl ester resins, or inorganic resins that are commonly used in anticorrosion paints, etc. And what contains the hardening | curing agent and other component corresponding to each resin as needed is suitable. These resins may be modified products or the like, and those in various known modes can be used.

  The above-described resins can be used alone or in combination. In addition, the types of the main component and curing agent of the resin composition as described above, properties, chemical index values (for example, epoxy equivalent in the epoxy resin composition, amine value, etc.), the mixing ratio of the main component and the curing agent, etc. , And can be adjusted appropriately according to the desired performance. Furthermore, if necessary, in order to improve the performance, a petroleum-based polymer resin, a coal-based polymer resin compound, and the like can be blended with the resin composition in the anticorrosion paint. For example, in order to improve the adhesion between the paint film formed from the edge cover paint and the paint film (such as antifouling paint film) that is overcoated therewith, a thermoplastic resin or an ester plasticizer is added. Is mentioned.

<Pigment>
The edge cover paint of the present invention may contain the following extender pigments, color pigments or rust preventive paints.

  Examples of extender pigments include talc, barium sulfate, mica, titanium oxide, silica, clay, calcium carbonate, kaolin, alumina white, white carbon, aluminum hydroxide, magnesium carbonate, and barium carbonate.

  Examples of the color pigment include organic color pigments such as naphthol red and phthalocyanine blue, and inorganic color pigments such as carbon black, dial, titanium white, barite powder, chalk, yellow iron oxide, and cobalt blue.

Examples of the antirust paint include zinc oxide, zinc powder, zinc phosphate, and zinc tripolyphosphate.
These pigments may be used singly or in combination according to the components such as the resin. In addition, the blending amount of the pigment can be adjusted as appropriate. For example, the blending amount of the extender pigment can be adjusted in terms of viscosity, workability, etc., depending on the type and molecular weight of the resin contained in the paint. What is necessary is just to be preferable.

<Solvent and other components>
The edge cover paint of the present invention can be in the form of a solvent type, a solventless type or an aqueous type (emulsion) depending on the type of resin used. In the case of a solvent-type paint, a conventionally used general solvent, for example, an aliphatic hydrocarbon solvent such as hexane; an aromatic solvent such as xylene and toluene; methyl isobutyl ketone (MIBK), cyclohexanone, etc. Ketone solvents; ether solvents such as propylene glycol monomethyl ether and propylene glycol monomethyl ether acetate (PGMAC); ester solvents such as ethyl acetate; alcohol solvents such as isopropyl alcohol can be used alone or in combination. . Such a solvent can be used in an appropriate amount so that the viscosity of the edge cover paint is suitable in view of coating property and the like.

  Others such as thixotropic agents, inorganic dehydrating agents (stabilizers), sagging inhibitors (thickening agents), anti-settling agents, bactericides, antifungal agents, anti-aging agents, antioxidants, antistatic agents, flame retardants Various additives generally blended and used in the base paint, such as a heat conduction improver and an antifoaming agent, can be blended in the edge cover paint of the present invention as required.

<Preparation of paint>
The viscosity of the edge cover paint of the present invention is not particularly limited, but is usually about 0.5 to 50 Pa · s from the viewpoint of workability (brush coating, roller coating, spray coating) in the coating process. Is done. Such viscosity depends on, for example, the type and molecular weight of the resin composition,
It can be appropriately adjusted by selecting the solvent to be used, the amount of extender pigment, the thickener, the leveling agent, and the like.

  The edge cover paint as described above can be produced by mixing, dispersing, and stirring the above-described components such as magnetic powder, resin composition, pigment, solvent and the like according to a conventional method. A base paint may be prepared separately in advance, and an edge cover paint may be produced by adding a magnetic powder to the base paint. When the base paint is a two-pack type, a magnetic powder is blended in at least one of the compositions, and when used, it may be mixed and used in the same manner as in the conventional two-pack paint preparation method. In other words, the edge cover paint of the present invention can be appropriately made into a one-pack type, two-pack type or more multi-pack type paint depending on the mode of the base paint.

Thick film coating method <Coating material>
The object to be coated with the edge cover paint in the present invention is typically a steel material used for the production of underwater / water structures, ships, land structures (buildings, bridges, etc.), etc. It is also possible to target other magnetic metal substrates to which a magnetic field having a predetermined magnetic flux density can be applied to the coating surface.

  According to the coating film forming method of the present invention, by using a magnetic field, coating is performed so that a sufficient film thickness (for example, the same level as the peripheral flat portion) is ensured with respect to the edges of such steel materials. can do. The “edge” in the present invention is a portion (for example, a right-angled portion generated by mechanically cutting a square member) at an end, a hole, a projection, or the like of a steel material. It refers to a portion where it is difficult to give the coating film a sufficient thickness by a normal coating method.

The edge to be coated in the present invention may be a sharp edge that is not subjected to edge treatment using a grinder, sandblast, etc., and a sufficient thick film coating film can be formed by the method described later, but it is necessary. Accordingly, the edge treatment may be performed. In that case, an ideal thick film can be formed. In addition, when rust, oil, moisture, dust, slime, salt, or the like adheres to the surface of the substrate, it is desirable to clean and remove it before applying the edge cover paint.

<Applying magnetic field>
In the method for forming a coating film according to the present invention, in a magnetic field, the step of applying a coating object such as steel with the edge cover paint as described above, and / or after applying the coating object with the edge cover paint, Before solidifying (losing fluidity), the method includes a step of allowing the applied object to stand in a magnetic field. The application of the edge cover paint and the standing until the paint is solidified is efficiently performed consistently in a magnetic field. However, even after the edge cover paint is applied in the absence of a magnetic field, the paint By placing it in a magnetic field before losing fluidity, it is possible to form a thick film at the edge as well.

  In the magnetic field, the surface magnetic flux density is different at each part of the steel material depending on the magnetization characteristics, and the magnetic flux density is higher at the edge and the protruding part than at the narrow plane part. For this reason, the paint containing the magnetic powder is attracted more toward the edge having a high magnetic flux density, and a thick film is formed there.

  The amount of paint attracted to the edge varies depending on the viscosity of the paint and the content of the magnetic substance, but tends to increase as the magnetic flux density on the edge surface increases. Conversely, the effect of attracting paint when the magnetic flux density is low. Becomes weaker. In the present invention, the magnetic flux density on the edge surface is preferably 5 millitesla (mT) or more in order to sufficiently attract various paints whose viscosity and magnetic powder content are in the above-mentioned predetermined ranges, More preferably, it is 300 mT.

  Application of a magnetic field to a surface to be coated such as steel can be performed using a magnet (permanent magnet), an electromagnet, or the like. For example, a steel material may be disposed above a magnet, a magnetic field is applied to the surface to be coated, an edge cover paint may be applied in this state, and left as it is. By adjusting the distance between the magnet and the target coating surface, or adjusting the strength of the electromagnet, the magnetic flux density can be set to a value within a desired range.

  What is necessary is just to adjust suitably also about the arrangement | positioning method of steel materials, a magnet, etc. according to steel materials, the shape of an edge, etc. In order to form an ideal coating film with a steel material edge, for example, it is desirable to arrange plate-shaped magnets horizontally and in a state where the angle bisector of the steel material edge is vertical. However, in the present invention, it is possible to form a sufficient thick film coating on the steel material edge without necessarily arranging in the above-described manner.

<Construction method>
When applying the edge cover paint of the present invention to all edges of a structure or the like, it is necessary to perform the construction before the assembly of a structure or a large block and at the stage of assembly of members or small units. Since application is easy and application is easy, it is efficient.

  In actual construction, when it is difficult to apply a magnetic field to the entire target edge, such as when painting an edge over a long distance, moving the magnet or electromagnet near the edge with a caster or the like, What is necessary is just to apply | coat, applying an appropriate magnetic field to an application | coating location. On the contrary, the magnet or electromagnet may be fixed and applied while moving the member.

Of course, the construction method is not limited to this, and it may be applied by applying a magnetic field to the edge after the entire structure is assembled.
<Coating and drying>
The means for applying the edge cover paint to the steel material is not particularly limited, and it may be applied in accordance with conventional methods such as brush coating, roller coating, spray coating, etc., which are generally used in factories or the field. it can. Conditions such as the moving speed of the coating apparatus, the feed pressure of the paint, the paint spraying air pressure, and the coating amount may be appropriately adjusted according to the composition, viscosity, and required dry film thickness of the paint used.

  As described above, after the edge cover paint is applied and solidified in a magnetic field, the coating film may be cured by drying or the like over a necessary period according to the form of the base paint according to a conventional method. As a result, a thick film coating film having a sufficient film thickness on the edge to prevent corrosion is formed.

Next, effects and the like of the present invention will be described in more detail based on examples. However, the following examples are merely illustrations of embodiments of the present invention, and the present invention is not limited thereto.
Examples 1 to 12, Reference Example 1 and Comparative Examples 1 and 2 were performed while changing the coating composition of the coating material and the magnetic flux density to be coated in the coating process. The essential points of these examples are as shown in Tables 1-15. In addition, all the numerical values in the table | surface which shows a compounding composition are a weight part.

  In the paints of Examples 1 to 4, different types of resins such as solvent-type and solvent-free type epoxy resins, chlorinated rubber, and acrylic resins are used. The target coating surface magnetic flux density at is also the same (100 ± 5 mT). Each of Examples 1 and 5 to 7 is a high solid modified epoxy resin-based paint, but the blending amount of magnetite magnetic powder is different. The type of magnetic powder was changed between Examples 1 and 8-9, and magnetite magnetic powder from a manufacturer different from that in Example 1 was used in Example 10. In Examples 11 and 12 and Reference Example 1, the same high solid modified epoxy resin paint (two-pack type) according to the present invention as in Example 1 is used, but the target coated surface magnetic flux density is changed. In particular, in Reference Example 1, coating is performed without applying a magnetic field, regardless of the coating method according to the present invention. Moreover, although the magnetic substance powder is not mix | blended with the coating material used by the comparative examples 1 and 2, other components (types, such as a varnish and a hardening | curing agent) are the same as the coating materials of Examples 1 and 3, respectively.

[Preparation of paint and specimen]
According to the formulations shown in Tables 1 to 15, paints used in Examples 1 to 12, Reference Example 1 and Comparative Examples 1 and 2 were prepared. The two-component paint was used by mixing the main agent and the curing agent at a predetermined ratio shown in the table. The components containing these pigments were dispersed in advance with a paint shaker to obtain a paint having a dispersity of 50 μm or less according to JIS K5600-2-5.

  Furthermore, in addition to the ingredients in the table, for spray workability, tap water is added to the water-based paint and dedicated thinner is added to the solvent-based paint in an amount of 5 to 15%, respectively, and the viscosity of each paint is 0.6. Adjusted to ˜1.5 Pa · s. The solventless paint was heated to 40 degrees to adjust the viscosity to the above range.

  On the other hand, as a test body to which the paint is applied, the material is SS-400 mild steel, the size is 20 × 20 × 500 mm, and the surface treatment (with # 180 paper is applied to a square bar whose angle (target edge) is 90 degrees. After polishing, what was degreased with a solvent was used.

[Coating method]
A steel plate base with a groove was placed on the plate magnet, and the test specimen was fixed in the groove (see FIG. 1). The surface magnetic flux density of the target edge of the test specimen was measured by using a Gauss meter “MG-601” manufactured by Magna, and setting the magnet and steel plate stand while measuring the magnetic flux density with the probe placed vertically in contact with the edge surface. The distance was adjusted to the predetermined values shown in Tables 1-15. In Reference Example 1 and Comparative Examples 1 and 2, the plate magnet was not arranged under the steel plate base.

  Subsequently, using an air spray, two passes were spray-coated from right above and both sides of the specimen. After leaving it in the magnetic field for 5 minutes after coating, the specimen was removed from the steel plate stand and allowed to dry in the room for 3 days. The coating specimen thus dried and cured was used as a test piece.

[Evaluation methods and results]
The sample was cut and sampled at three central portions of the test piece by a cutting machine. Each target cross section was observed at a magnification of 100 times, and the film thickness on both sides of the edge (vertex) and 10 mm position from the edge was measured. And based on the following formula, the film thickness retention of three edges was calculated, and the average (three-point average) of them was obtained.

The results are shown in Table 16. Compared to the case of using the conventional paint and the coating method (Comparative Examples 1 and 2), according to the present invention, using the edge cover paint blended with the magnetic powder, and applying the steel material coating in a magnetic field It has been shown that a sufficient film thickness can be applied to the edge.

[Support for various edges]
If this invention is utilized, a thick film coating film can be formed efficiently also on various edges having various shapes. In Examples 14 to 17, the target edge of the test specimen was subjected to various treatments as described below, and the other specimens were prepared using the same paint and the same conditions as in Example 1;
Example 14: A grinder was applied to the target edge once (no burr processing),
Example 15: A grinder was applied to the target edge once (with a burr process),
Example 16: The grinder was applied to the target edge three times.
Example 17: The target edge was sandblasted.

  The enlarged photograph of the cut surface of the test piece by Examples 14-17 and the enlarged photograph of the cut surface of the test piece of the comparative example 1 used as a control are shown in FIGS.

The model figure which shows the coating method in an Example etc. The enlarged photograph of the cross section of the edge in Example 14 (the grinder 1 time, without a burr process). It is shown that a thick film was also formed on the protrusions of the burrs. The enlarged photograph of the cross section of the edge (with a grinder 1 time and a fogging process) in Example 15. FIG. It is shown that thick films were formed at the corners. The enlarged photograph of the edge (grinder 3 times) cross section in Example 16. FIG. It is shown that a thick film was formed along the shape of the angular protrusion. The enlarged photograph of the edge (sandblasting) cross section in Example 17. It is shown that an ideal thick film was formed at the corner. The enlarged photograph of the edge cross section in the comparative example 1. FIG. It has been shown that when a conventional general paint is used for coating, the edge is hard to be coated and thinned.

Explanation of symbols

1: Magnet 2: Steel plate base 3: Specimen (surface treated steel)
4: Air spray 5: Target edge

Claims (6)

  An edge cover paint for corrosion protection of steel edges, containing 3 to 40% by weight of magnetic powder in the solid content of the paint.   The edge cover paint according to claim 1, wherein the magnetic powder is made of magnetite, ferrite, or a mixture thereof.   The alkyd resin, chlorinated rubber, vinyl resin, acrylic resin, epoxy resin, urethane resin, polyester resin, vinyl ester resin, or inorganic resin is contained in addition to the magnetic substance powder. Edge cover paint as described in.   A step of applying the edge cover paint according to any one of claims 1 to 3 to a steel material edge in a magnetic field, or after applying the edge cover paint according to any one of claims 1 to 3 to a steel material edge, A method for forming a thick film coating on a steel material edge, characterized by comprising a step of placing the step, or both steps.   The method of forming a thick film coating film according to claim 4, wherein the surface magnetic flux density of the edge by a magnetic field is 5 millitesla (mT) or more.   A ship, an underwater / water structure or a land structure painted by the thick film forming method according to claim 4.