KR20110122689A - Precoated metal sheet and process for producing same - Google Patents

Abstract

At least, it is a precoat metal plate which has a top coat layer which is a coating film formed in the outermost surface, and an intermediate coating film layer which is an undercoat which contact | connects the said top coat layer, The said precoat metal plate is a top coat layer containing a silicone graft acrylic resin, And a clear coating film containing no pigment, wherein the intermediate coating film layer contains a melamine cured or isocyanate cured polyester resin, further contains a colored pigment, and the average friction coefficient of the coating film surface is 0.08 or less, and the coating film surface The hardness at 23 ° C. is 75 to 200 N / mm 2 at the universal hardness under a 5 mN load, and the glossiness of the mirror surface of the coating film surface is 50% or more when measured under the conditions of an incident angle and a light receiving angle of 20 °, respectively. There is provided a precoat metal sheet having designability such as gloss and sensibility and excellent damage resistance.

Description

Precoated metal sheet and its manufacturing method {PRECOATED METAL SHEET AND PROCESS FOR PRODUCING SAME}

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a precoated metal sheet and a method of manufacturing the same, and in particular, for use in household appliances, building materials, civil engineering, machinery, automobiles, furniture, containers, etc. It relates to a precoat metal plate having compatibility, and a method for producing the same.

For example, a precoat metal plate processed in a state in which a colored film is coated in advance is used in place of a post-coated product which is coated after processing a conventional metal plate to an outer plate such as a home appliance field, a building material field, or an automobile field. It has been possible. On the other hand, in these uses, the request | requirement of the coating appearance with high gloss is high for the coating from a viewpoint of a design and designability.

As a technique of improving the glossiness of a coating film, the technique of reducing the surface roughness of the metal plate which is a base material, for example as described in patent document 1, for example, the coating film using resin with low molecular weight as described in patent document 2 The technique which coats | coats, for example, the technique of coating a clear coat film on a coloring coat layer as disclosed in patent document 3 is disclosed.

When industrially producing a precoat metal plate, it is generally manufactured by the continuous coating line called a coil coating line, as described, for example in nonpatent literature 1. In a normal coil coating line, a primer coating having a rust preventing function is coated on a metal plate by a coating apparatus called a roll coater or a curtain coater, baked in a hot air oven or the like, and then coated with a coating apparatus and then baked. 2 paints twice baking (commonly referred to as a 2 coat 2 bake method) is common. Therefore, when attempting to coat the coating film which is excellent in sensibility, such as a clear paint, on a colored layer, since the number of application | coating times is three or more times, a large amount of equipment investment is needed, and a coating apparatus and an oven are added, or a coil coating line is twice. Correspondence, such as mailing and painting, was needed. However, as a means of solving this, the wet-on-wet coating method which coats a coating material in the undried state as described in patent documents 4-12 is known.

On the other hand, since a precoat metal plate is used after shaping | molding after coating, damage resistance at the time of shaping | molding process is calculated | required. It is also important to prevent scratches that occur during transportation or during assembly by hand. For example, in Patent Document 13, a polyester resin having a glass transition point of 5 to 40 ° C, a number average molecular weight of 15,000 to 30,000, and a hexamethoxy metholated melamine resin is blended in a mass ratio of 75/25 to 55/45. Coating composition for the coating metal plate which is high in coating film hardness, excellent in damage resistance, and excellent in workability by the coating material which mix | blends 1-2 mass parts of amine block bodies of dodecyl benzene sulfonic acid with respect to 100 mass parts of polyester-melamine resins. Is disclosed. Patent Documents 14 and 15 disclose a technique of increasing the hardness and improving damage resistance by adding glass fibers and glass beads to a coating film. Patent Literatures 16 and 17 disclose a technique of increasing the lubricity by adding a resin bead or wax to a coating film to improve damage resistance.

Japanese Patent Application Laid-open No. Hei 7-150326 Japanese Patent Application Laid-open No. Hei 1-304934 Japanese Patent Application Laid-open No. Hei 10-66931 Japanese Patent Application Laid-Open No. 11-19581 Japanese Patent Application Laid-Open No. 11-19582 Japanese Patent Application Laid-Open No. 11-19583 Japanese Patent Application Laid-open No. Hei 11-19584 Japanese Patent Application Laid-open No. Hei 11-19585 Japanese Patent Application Laid-open No. Hei 11-19586 Japanese Patent Application Laid-open No. Hei 11-57608 Japanese Patent Application Laid-open No. Hei 11-76932 Japanese Patent Application Laid-open No. Hei 11-76933 Japanese Patent Application Laid-open No. Hei 2-269168 Japanese Patent Application Laid-open No. 63-5938 Japanese Patent Application Laid-open No. Hei 4-11671 Japanese Patent Application Laid-Open No. 2004-98624 Japanese Patent Application Laid-open No. 2004-34591

Ueda et al., Colorant, 72 (8), 525-531 pages (1999)

However, the method of obtaining high gloss and high stiffness by controlling the surface roughness of the base material of the precoat metal plate low can provide relatively high gloss while controlling the surface roughness of the metal plate as the base material even if any coating film is used. It is necessary to control the surface roughness of the metal plate serving as the base material by rolling the metal by a rolling roll or the like adjusted with this or by polishing with a polishing machine or the like. Therefore, manufacturing a high gloss precoat metal plate by this method requires a lot of labor and cost, and it is difficult to mass-produce industrially.

On the other hand, the method of obtaining a high gloss precoat metal plate by coating the coating material using resin with a low molecular weight can be manufactured relatively easily compared with the method obtained by controlling the surface roughness of the metal plate which is a base material, Since it must be used for coating, it is difficult to provide another coating film performance, for example, workability.

As a method of obtaining a high gloss precoat metal plate relatively easily without using resin which has a performance limitation, there is a method of coating a transparent clear coating film on the colored coating film layer of patent document 13. As shown in FIG. Although the manufacturing problem when applying this method to the coil coating line of the existing 2-coat 2-baking specification can be solved by applying wet-on-wet coating as mentioned above, about performance (for example, patent document 13 ), Excellent gloss can be obtained, but sufficient damage resistance cannot be obtained.

Moreover, although the effect which adds glass beads to the clear coating film on the colored coating film disclosed by patent document 14, 15 is effective in improving coating film hardness, it was not enough to satisfy damage resistance. In addition, in the addition of the wax in the clear coating film on the colored coating films disclosed in Patent Documents 16 and 17, the lubricity is improved, but also sufficient damage resistance cannot be obtained. In addition, addition of glass beads and wax to these coatings lowers the glossiness of the coating film, and is therefore not suitable for applications requiring a glossy appearance.

As mentioned above, although the prior art about the precoat metal plate excellent in the designability, such as glossiness and linerability, is seen, the reality is not disclosed about the precoat metal plate excellent in the design resistance, such as glossiness and the linerability, and also excellent in damage resistance.

Accordingly, an object of the present invention is to provide a precoated metal sheet having high gloss and lightness and excellent damage resistance, and a method for producing the same.

MEANS TO SOLVE THE PROBLEM The present inventors earnestly examined in order to obtain the high glossiness and clarity, and also sufficient damage resistance from the knowledge until now, It is insufficient to only make the hardness of a coating film high or only lubricity like the prior art, It is found that it is necessary to make both coating film hardness and high lubricity compatible, and for that purpose, the top coating film is made into a clear layer containing a silicone graft acrylic resin, and the intermediate coating film layer contains a melamine cured or isocyanate cured polyester resin. By making it a structure, it discovered that the improvement of the hardness of a coating film and the reduction of a friction coefficient can be achieved, ensuring a high glossiness, and it is excellent in both designability and damage resistance, such as glossiness and stiffness, and also excellent workability. It discovered that the precoat metal plate was obtained.

This invention is completed based on this knowledge, and what this invention makes the summary is as follows.

[1] a precoat metal sheet having a coating layer on one or both surfaces of the metal sheet,

The said coating film layer has at least the top coating film layer which is the coating film formed in the outermost surface, and the intermediate coating film layer which is a lower coating film which contact | connects the said top coating film layer,

The top coating layer is a clear coating film containing a silicone graft acrylic resin and not containing a pigment, and the intermediate coating film layer is a coating film containing a melamine cured or isocyanate cured polyester resin and containing a colored pigment. ,

The average coefficient of friction of the coating layer surface of the coating layer is 0.08 or less, the hardness at 23 ° C. of the coating layer surface is 75 to 200 N / mm 2 in universal hardness under 5 mN load, and the mirror surface glossiness of the coating layer surface The incidence angle and the light reception angle are each 50% or more when measured on the conditions of 20 degrees, The precoat metal plate characterized by the above-mentioned.

[2] a precoat metal sheet having a coating layer on one or both surfaces of the metal sheet,

The said coating film layer has at least the top coating film layer which is the coating film formed in the outermost surface, and the intermediate coating film layer which is a lower coating film which contact | connects the said top coating film layer,

The top coating layer is a clear coating film containing a silicone graft acrylic resin and further containing a pigment, the intermediate coating film layer is a coating film containing a melamine curable or isocyanate curable polyester resin and further containing a colored pigment,

The average coefficient of friction of the coating layer surface of the coating layer is 0.08 or less, the hardness at 23 ° C. of the coating layer surface is 75 to 200 N / mm 2 in universal hardness under 5 mN load, and the mirror surface glossiness of the coating layer surface The incidence angle and the light reception angle are each 50% or more when measured on the conditions of 20 degrees, The precoat metal plate characterized by the above-mentioned.

[3] The precoat metal sheet according to [2], wherein the top coating layer is a clear coating film containing a bright pigment.

[4] The precoat metal sheet according to [1] or [2], wherein the top coating layer is a melamine curable type.

[5] The precoat metal sheet according to [1] or [2], wherein the top coating layer is an isocyanate curable type.

[6] The precoat metal sheet according to [5], wherein the ratio of NCO / OH is 0.05 to 0.5 in the isocyanate curable top coating layer.

[7] The precoat metal sheet according to any one of [1] to [6], wherein Ra (center line average roughness) of the interface between the top coating film layer and the intermediate coating film layer is 0.3 to 0.8.

[8] The precoat metal plate according to any one of [1] to [7], wherein a content of the silicone graft acrylic resin in the top coating film is 2 to 18% by mass in terms of silicone resin.

[9] The glass transition temperature of the top coating film is 30 to 67 ° C, the proportion of the silicone resin in the silicone graft acrylic resin contained in the top coating film is 3 to 20 mass%, and the glass transition temperature of the intermediate coating film is It is 25-50 degreeC, The precoat metal plate in any one of [1]-[8].

[10] The precoat metal sheet according to any one of [1] to [8], wherein the hardness at 23 ° C. on the surface of the coating film layer is 150 to 200 N / mm 2 at a universal hardness under a 5 mN load.

[11] The precoat metal sheet according to [10] or [11], wherein the top coating layer is an isocyanate curable type.

[12] The precoat metal sheet according to [11], wherein the curing agent in the top coating layer is isophorone diisocyanate (IPDI).

[13] The precoat metal sheet according to [11] or [12], wherein a ratio of the curing agent in the top coating layer is 0.1 to 0.5.

[14] A precoat metal sheet having a coating layer on one or both surfaces of the metal sheet,

The coating layer has at least a top coating layer, which is a coating film formed on the outermost surface, an intermediate layer in contact with the top coating layer, and an intermediate coating film layer, which is an undercoat in contact with the intermediate coating layer,

The top coating layer is a clear coating film containing a silicone graft acrylic resin and not containing a pigment, and the intermediate coating film layer is a coating film containing a melamine cured or isocyanate cured polyester resin and containing a colored pigment. ,

The average coefficient of friction of the coating layer surface of the coating layer is 0.08 or less, the hardness at 23 ° C. of the coating layer surface is 75 to 200 N / mm 2 in universal hardness under 5 mN load, and the mirror surface glossiness of the coating layer surface The incidence angle and the light reception angle are each 50% or more when measured on the conditions of 20 degrees, The precoat metal plate characterized by the above-mentioned.

[15] The precoat metal sheet according to [14], wherein the intermediate layer contains a pigment.

[16] The precoat metal sheet according to [15], wherein the intermediate layer contains a bright pigment.

[17] The precoat metal sheet according to any one of [14] to [16], wherein Ra (center line average roughness) of the interface between the top coating layer and the intermediate layer is 0.3 to 0.8.

[18] A method for producing a precoat metal sheet according to any one of [1] to [17].

A method of producing a precoated metal sheet, wherein the intermediate coating film layer and the top coat layer are coated with a multilayer simultaneous coating or a wet on wet method, respectively, and then baked.

ADVANTAGE OF THE INVENTION According to this invention, the precoat metal plate, its manufacturing method, and the coating metal molded object which are high in glossiness and high contrast, and excellent in damage resistance and workability can be provided.

1: is a schematic cross section for demonstrating the measuring method of center line roughness Ra.

EMBODIMENT OF THE INVENTION Below, preferred embodiment of this invention is described in detail.

The precoat metal plate of this invention has a coating film layer of two or more layers, and since a top coating film is a clear coating film, the surface is smooth and the high gloss which the mirror glossiness measured on the conditions of 20 degrees of incidence angles and light reception angles respectively is 50% or more. Can be obtained. Here, the clear coating film refers to a coating film having a low transparency of pigment in the coating film and a small hiding power of the foundation.

By containing a predetermined amount of the silicone graft acrylic resin in the top coating film, the average friction coefficient is 0.08 or less, and a high lubrication activity and high hardness of 75 to 200 N / mm 2 or more at a universal hardness under a 5 mN load of hardness at 23 ° C can be obtained. In addition, both damage resistance and high gloss can be achieved.

In order to ensure the damage resistance of the precoat metal plate of this invention, it is necessary to make an average friction coefficient into 0.08 or less. Here, the average friction coefficient measures the force F applied when the stainless steel ball (10 mm) is moved in parallel on the precoat metal plate 110 mm under a condition of 100 g load and 150 mm / min. The average of the measured value of the force F in the multiple site | part in the range of 100 mm remaining except 10 mm is calculated.

When the average friction coefficient exceeds 0.08, the frictional force when the foreign matter comes into contact with the surface of the precoat metal plate and rubs against the surface of the precoated metal sheet during molding is increased, and the coating surface is destroyed, resulting in poor damage resistance. By setting the average friction coefficient to 0.08 or less, the frictional force when the surface of the precoat metal sheet rubs against the mold or foreign matter is reduced, and the damage resistance is improved. In order to obtain stable damage resistance, the average friction coefficient is more preferably 0.05 or less.

Moreover, in order to ensure the damage resistance of the precoat metal plate of this invention, the universal hardness of the surface needs to be 75-200 N / mm <2>. Here, universal hardness refers to the coating film hardness measuring method of DIN # 50359-1 of Germany, and the four angle pyramid (Vickers hardness test of JIS-Z-2244 described in JIS-Z-2244) whose facing angle formed from diamond is 136 degrees. The same) is pressed against the material surface to calculate the hardness from the indentation depth under the working load conditions. In addition, the universal hardness in this invention shall be measured on the conditions of 23 degreeC of temperature, 5 mN of indentation loads, and using the micro hardness tester of this DIN standard. When universal hardness is less than 75 N / mm <2>, even if an average friction coefficient is 0.08 or less, since coating film hardness is low, damage resistance is inferior. When universal hardness exceeds 200 N / mm <2>, since a coating film becomes too hard and it becomes difficult to ensure workability, it is unsuitable. As for universal hardness, 75-200 N / mm <2> is suitable.

When abrasion resistance is also needed, it is preferable to control universal hardness to 150-200 N / mm <2>.

In addition, the specular glossiness of the surface of the precoat metal plate coating film of this invention can be measured according to JIS Z 8741, and needs to be 50% or more, when an incident angle and a light receiving angle are measured on the conditions of 20 degrees, respectively. If it is less than 50%, the appearance quality deteriorates.

The top coat layer of the precoat metal sheet of the present invention is characterized by containing a silicone graft acrylic resin as described above. The silicone graft acrylic resin is obtained by graft polymerization of a silicone resin on an acrylic resin backbone. Excellent lubricity can be effectively obtained by the excellent strength and transparency of the main chain acrylic resin, and the property that the silicone resin stretched into the branch shape from the main chain is easily coordinated on the coating film surface. Moreover, since silicone resin has high lubricity and comparatively excellent strength, the coating film formation excellent in gloss, hardness, and lubricity becomes possible by containing a silicone graft acrylic resin in a top coating film layer.

By making the top coating film layer of the precoat metal plate of this invention into the clear coating film containing a pigment, designability can be improved further.

By making the top coating film layer of the precoat metal plate of this invention into a clear coating film containing a bright pigment, a flaw resistance can also be improved by improving designability and making a scratch less prominent.

It is preferable that content of the silicone graft acrylic resin in a top coating film is 2-20 mass% in conversion of silicone resin. When content of the silicone graft acrylic resin in a coating film is less than 2 mass%, lubricity is not enough and it is difficult to ensure damage resistance. If it exceeds 20 mass%, there exists a possibility that the storage stability of paint may fall, and stable manufacture becomes difficult. In addition, "silicone resin conversion" here means showing content of a silicone graft acrylic resin using content of the total amount of the silicone monomer contained in a top coating film.

Resin other than the silicone graft acrylic contained in the top coating film can be used without problem as long as it is compatible with the silicone graft acrylic resin, but an acrylic resin having excellent compatibility with the silicone graft acrylic resin and having excellent strength and transparency is most suitable. Do.

The crosslinking agent of the top coating film is preferably a melamine resin or an isocyanate compound. The melamine resin is higher in hardness than the isocyanate compound, and it is easy to obtain a predetermined coating film hardness. However, when a melamine resin is concentrated on the surface of a coating film, such as using an amine block body of dodecyl benzene sulfonic acid, it becomes difficult to coordinate a silicone resin to a coating film surface, and lubricity may fall.

It is preferable that the compounding quantity at the time of using melamine resin as a crosslinking agent is 5-30 mass parts with respect to 100 mass parts of silicone graft acrylic resin from a viewpoint of ensuring the hardness and lubricity of a top coat film.

On the other hand, when the melamine resin is used as a crosslinking agent and left at a high temperature, the reaction with the silicone graft acrylic resin is likely to proceed, and the storage stability of the paint may be deteriorated. From the viewpoint of the storage stability of the paint, the isocyanate compound is a melamine resin. More preferred.

When using an isocyanate compound normally, the molar ratio of NCO / OH shall be 0.9 / 1.0 or more. This is because when the molar ratio of NCO / OH is lower than 0.9 / 1.0, crosslinking is insufficient and the coating film is excessively soft.

However, the present inventors investigated in detail the relationship between the molar ratio of NCO / OH and the performance. When the silicon graft acrylic resin is used as the main resin, the molar ratio of NCO / OH is generally lower than the value that was considered to be optimal. It was found that the molar ratio of OH can balance hardness and workability at a high level at 0.05 / 1.0 to 0.5 / 1.0. This is because the silicone graft acrylic resin is harder than the isocyanate compound, so the molar ratio of NCO / OH is low, that is, the amount of the isocyanate compound is low, so that a rigid coating film can be obtained, and the crosslinking density is low, so that high workability can be obtained. It is estimated. However, when the molar ratio of NCO / OH is lower than 0.05 / 1.0, crosslinking density may be too low and coating film hardness may not be obtained.

When isophorone diisocyanate is used as an isocyanate compound, high coating film hardness is easy to be obtained. This is because isophorone diisocyanate has a rigid skeleton.

When using an isocyanate compound as a hardening | curing agent of a coating film, it is usually necessary to make molar ratio of NCO / OH into 0.9 / 1.0 or more. This is considered to be because when the molar ratio of NCO / OH is less than 0.9 / 1.0, the amount of isocyanate groups contributing to the crosslinking reaction becomes excessively small, the film hardness improvement effect due to the crosslinking reaction is insufficient, and the coating film becomes too soft.

However, in the present invention using a silicone graft acrylic resin as the main resin, it is found that when the molar ratio of NCO / OH is 0.9 / 1.0 or more, the coating film hardness is lowered than the molar ratio of NCO / OH is less than 0.9 / 1.0. Could. MEANS TO SOLVE THE PROBLEM As a result of investigating the relationship between the molar ratio of NCO / OH and performance when using a silicone graft acrylic resin as a main resin in detail, the molar ratio of NCO / OH is 0.05 / lower than what was normally considered optimal. By setting it as 1.0-0.5 / 1.0, it discovered that hardness and workability can be balanced at a high level.

This is because the hardness of the silicone graft acrylic resin is higher than that of the isocyanate compound and is harder, so that the lower the molar ratio of NCO / OH, that is, the smaller the amount of the isocyanate compound, can obtain a hard coating film, and the crosslinking density is lower. It is presumably because it is excellent in ductility and high workability can be obtained. However, when the molar ratio of NCO / OH is lower than 0.05 / 1.0, crosslinking density is too low and it is unpreferable since it may not fully form a film and the film strength itself may fall.

When isophorone diisocyanate is used as an isocyanate compound, high coating film hardness is easy to be obtained. This is because isophorone diisocyanate has a rigid skeleton.

As for the glass transition temperature of a top layer, 30-67 degreeC is preferable. When glass transition temperature is lower than 30 degreeC, coating film hardness may become low and damage resistance may fall. When glass transition temperature is higher than 67 degreeC, coating film hardness may increase too much and may fall off and workability may fall.

As for the ratio of the silicone resin in a silicone graft acrylic resin, 3-20 mass% is preferable. When the ratio of the silicone resin in a silicone graft acrylic resin is lower than 3 mass%, the coordination of the silicone resin to the top coating film layer surface may become inadequate, lubricity may become low, and damage resistance may fall. When the ratio of the silicone resin in a silicone graft acrylic resin is higher than 20 mass%, there exists a possibility that the storage stability of a coating material may fall.

As for the film thickness of a top coating film layer, 1-10 micrometers is preferable. If the film thickness of the top coating layer is less than 1 µm, the intermediate coating layer may not be completely covered, and glossiness and lubricity may decrease. When the film thickness of a top coat layer exceeds 10 micrometers, there exists a possibility that workability may fall. In addition, it is not preferable in terms of cost.

The intermediate coating film layer contains a melamine curable or isocyanate curable polyester resin and further contains a colored pigment. Moreover, it is preferable that the glass transition temperature of an intermediate coating film layer is 25-50 degreeC. The reason why the main resin of the intermediate | middle coating film layer was limited to polyester resin is to ensure processability by making polyester resin excellent in ductility and adhesiveness into an intermediate | middle coating layer. Moreover, the reason which limited the glass transition temperature of an intermediate | middle coating coat layer is that there exists a possibility that hardness may run short when the glass transition temperature of an intermediate | middle coating film layer for compatibility with workability and hardness is less than 25 degreeC, and when it exceeds 50 degreeC, Since workability may run short, the glass transition temperature of an intermediate | middle coating film layer shall be 25-50 degreeC.

The intermediate coating film can be used in combination with a resin other than the polyester resin of the main resin. However, in order to ensure ductility and adhesiveness, which are the characteristics of the polyester resin described above, the concentration of the polyester resin contained in the intermediate coating is 70 mass. It is preferable to set it as% or more. The kind of resin other than the polyester resin which can be used for an intermediate coating film does not need to specifically limit, It can select suitably and can use suitably what does not have a bad influence on the performance and paintability of a coating film.

As for the film thickness of an intermediate coating film layer, 5-20 micrometers is preferable. Since the top coat layer is harder than the intermediate coating film layer of the precoat metal sheet of the present invention, the thicker the film thickness of the intermediate coating film layer is, the greater the influence on the hardness of the entire coating film of the intermediate coating film layer becomes. Since the universal hardness may be 75 N / mm <2> or less when the film thickness of an application | coating coating layer exceeds 20 micrometers, it is preferable to set it as 20 micrometers or less. Moreover, when the film thickness of an intermediate coating film layer is less than 5 micrometers, since the concealment rate by a pigment may fall and it may become difficult to give a color, the film thickness of an intermediate coating film is 5 micrometers or more. In addition, the thickness of the intermediate coating film is preferably 5 µm or more from the viewpoint of securing the ductility of the film.

In addition, the glass transition temperature of the coating film in the precoat metal plate of this invention means the glass transition temperature as a bulk of the coating film after adding these, in the case of the coating film containing a pigment and a hardening | curing agent. The glass transition temperature of a coating film may peel off the coating film coated on the precoat metal plate, and may measure it using a differential scanning calorimetry apparatus (generally called DSC), and it is a thermomechanical analyzer in the state coated as a precoat metal plate. (Typically called TMA) may be used. In addition, you may measure by other generally well-known methods. Moreover, it is known that the glass transition temperature of a coating film generate | occur | produces some error by a measuring instrument or a measurement condition. Therefore, in the present invention, the glass transition temperature of the coating film is the range of the present invention when measured by any one of a plurality of generally known glass transition temperature measuring methods, that is, a method using DSC or a method using TMA. Back side shall be included in this invention. Since the glass transition temperature of a coating film is mainly dominated by the glass transition temperature of a base resin, the glass transition temperature of a coating film can be adjusted by controlling the glass transition temperature of a base resin.

It is more suitable if Ra (center line average roughness) of the interface of the top coating film layer of this invention and an intermediate | middle application coating film layer is 0.3-0.8 micrometer. When Ra of the interface of a coating film is less than 0.3 micrometer, there exists a possibility that the adhesiveness of the said coating film interface may fall. In general, in the case of laminating the coating films, the adhesion of the coating films is maintained by chemical bonds between the coating films, physical bonding such as hydrogen bonds, van der Waals forces, and the like. Adhesion by the anchor effect is given. However, when Ra of the interface of each coating film exceeds 0.8 micrometer, it may affect an external appearance and gloss may fall.

In the present invention, the interface Ra can be measured by the following method (basically, the method according to JIS-B-0601-1982).

After photographing the vertical cross section of the interface on which the surface roughness Ra is to be measured with a micrograph, the unevenness of the interface is traced, and according to a predetermined formula defined in JIS-B-0601-1982 (see Examples described later), The centerline average roughness of this interface can be obtained.

In order to coat a clear clear coating film again on a coloring coating layer, the precoat metal plate of this invention adds an additional coating apparatus and oven, or mails a coil coating line twice in manufacture in the facility of the existing 2-coat 2 baking specification. It becomes necessary. However, by coating the top coating film and the intermediate coating film by multilayer simultaneous coating or wet on wet, the precoat metal sheet of the present invention can be manufactured in a facility of a conventional two coat two bake specification. In addition, the provision of Ra of the above-described interface can be achieved by multilayer co-application or wet on wet, and as described later, the appearance of a good processed portion can be obtained by applying the coating by multilayer co-application or wet on wet. Therefore, these points are also preferable.

Multi-layer simultaneous coating in this invention is a method of apply | coating to a base material in the state which laminated | stacked several layers of coating liquids, such as a slot die coater or a slide hopper type curtain coater, simultaneously, and then carrying out multilayer baking simultaneously.

In addition, wet-on-wet coating means that after apply | coating a coating liquid on a base material once again, while this coating liquid is in the wet state before drying, another coating liquid is apply | coated again on it, and this laminated multilayer coating liquid is applied simultaneously. It is a method of dry baking, for example, after coating a lower coat with a roll coater, a curtain flow coater, etc., and before baking this, after coating an upper coat with a coating method, such as a curtain flow coater, the multilayer coat of a lower coat and an upper coat How to bake at the same time.

By these methods, the coating liquid of undried state is laminated | stacked and simultaneously apply | coated, and the density | concentration gradient layer can be formed in an interface by slightly mixing the coating liquid of each layer in an interface. The concentration gradient layer in the present invention has a structure in which the top coating layer is hard and gradually softens toward the intermediate coating layer. Therefore, even if a crack occurs in the hard top coating layer due to bending or the like, the progress of the crack is suppressed by the concentration gradient layer at the interface and does not reach the intermediate coating film layer. Since the top coating layer is clear, if the crack remains only in the top coating layer, the effect on the appearance is slight and does not matter. Further, by laminating and simultaneously applying the undried coating liquid, excellent adhesion between the intermediate coating film layer and the top coating layer can be obtained by slightly mixing the coating liquids at each interface.

The method of simultaneously baking the multilayer coating of the present invention or the coating film coated with wet on wet coating is generally a known coating baking, for example, a hot air drying furnace, an induction heating furnace, an infrared heating furnace, or a combination thereof. Etc. can be used.

As a coloring pigment added to the intermediate coating film layer of the precoat metal plate of this invention, a well-known inorganic pigment, organic pigment, and metallic pigment can be used generally. Specific examples include carbon black, titanium oxide, zinc oxide, naphthol red, disazo yellow, disazo filler zoro orange, aluminum pigment, nickel pigment and the like. Generally, when it is a black system and a deep color system, a flaw is easy to be outstanding and it is difficult to ensure damage resistance, but this invention exhibits an effect without a problem even if it is a black system or a deep color system, and expresses favorable damage resistance.

The metal plate used for this invention can use a well-known metal material generally. The metal material may be an alloy material. For example, steel plate, stainless steel plate, aluminum plate, aluminum alloy plate, titanium plate, copper plate, etc. are mentioned. The surface of these materials may be plated. As a kind of plating, zinc plating, aluminum plating, copper plating, nickel plating, etc. are mentioned. Alloy plating of these may be sufficient. In the case of steel sheet, generally known steel plate and plated steel sheet are applied, such as hot dip galvanized steel sheet, electro galvanized steel sheet, zinc-nickel alloy coated steel sheet, hot-dip galvanized steel sheet, aluminum plated steel sheet, aluminum-zinc alloy plated steel sheet, etc. can do.

Generally the well-known chemical conversion treatment is given to the surface of the metal plate used for this invention, Since adhesiveness of a metal plate and a coating film layer improves, it is more suitable. As the chemical conversion treatment, zinc phosphate chemical conversion treatment, coating chromate treatment, electrolytic chromic acid treatment, reaction chromate treatment, chromate free chemical conversion treatment, or the like can be used. As chromate-free chemical conversion treatment, the thing processed by the aqueous solution containing a silane coupling agent, a zirconium compound, a titanium compound, tannin or tannic acid, resin, silica, etc. is known, Unexamined-Japanese-Patent No. 53-9238, Japan Japanese Patent Application Laid-open No. Hei 9-241576, Japanese Patent Application Laid-Open No. 2001-89868, Japanese Patent Application Laid-Open No. 2001-316845, Japanese Patent Application Laid-Open No. 2002-60959, Japanese Patent Application Laid-Open No. 2002- You may use the well-known technique described in 38280, Unexamined-Japanese-Patent No. 2002-266081, Unexamined-Japanese-Patent No. 2003-253464, etc. These chemical conversion treatments are commercially available, for example, the chromate treatment "ZM-1300AN" made by Nippon Parkarizing Co., Ltd., the chromate-free chemical conversion treatment "CT-E300N" made by Nippon Parkarizing Company, and the trivalent chromium-based chemical treatment made by Nippon Paint Company. "Surf coat (registered trademark) NRC1000" etc. can be used.

The precoat metal plate of this invention can coat the primer coating film which has an antirust coating function as needed. Coating the primer coating film is more suitable because the corrosion resistance of the metal plate is improved. As a primer coating film which coats the precoat metal plate of this invention, generally the well-known primer coating film for precoat metal plates, for example, a polyester primer, an epoxy primer, a urethane primer, etc. can be used. The hardening | curing agent of a primer coating film may be either melamine type or an isocyanate type. Although the well-known thing, such as a chromate type, a phosphoric acid type, and a silica type, can be used for the antirust pigment added to a primer coating film, since it is excellent in an environment other than a chromate type, it is more suitable. The primer coating film to be coated on the precoat metal sheet of the present invention is generally coated by a known coating method, for example, a roll coater, a roller curtain coater, a ringer roll coater, spray coating, or the like, and then generally used for a known paint Baking furnace, for example, can be baked in a hot air drying furnace, induction heating furnace, infrared heating furnace, or a furnace using these in combination.

Next, although an Example is used and this invention is demonstrated in detail, this invention is not limited to a following example.

Hereinafter, the experiment will be described in detail.

First, the top paint used in the experiment is explained in detail.

100 parts by mass of isopropyl alcohol was placed in a glass reactor equipped with a mechanical stirring device, a thermometer, a condenser, and a dry nitrogen gas inlet, and heated to 80 ° C. under a dry nitrogen atmosphere. It was dripped over 2 hours by the dropping funnel, and after hold | maintaining at the same temperature for 4 hours, reaction was complete | finished. In this way, a graft copolymer solution was obtained. The graft copolymer solution obtained in the mixed solutions 1 to 12 is referred to as the graft copolymer solution 1 to 12.

In addition, a silicone graft acrylic resin, which is a commercially available product, was also used. "Rejeda (registered trademark) GS-1015" (glass transition temperature 54 degreeC) by Toa Kosei Co., Ltd. was used.

In addition, "U double (registered trademark) S-2710" (glass transition temperature 40 degreeC) and "acreset (registered trademark) AST-5892" (glass transition temperature 70 degreeC) which are acrylic resins made by Nippon Shokubaisha (Top-16 to 18 of Table 2).

In addition, "Byron (registered trademark) GK810" (glass transition temperature 46 degreeC) which is an amorphous polyester resin made by Toyobosha was used as the comparative level which does not use the silicone draft acrylic resin.

As a crosslinking agent, "Super Bectamine" (registered trademark) J830, which is a butylated melamine resin (hereinafter referred to as butylated melamine) manufactured by Dainippon Ink & Chemicals Co., Ltd., a fully alkylated methylated melamine resin (hereinafter referred to as Mitsui Cytech Co., Ltd.) Cymel® 303, which is called methylated melamine, Death Module BL3175 (trade name) (hereinafter referred to as HDI), an isocyanate compound made by Sumika Bayer Urethane Co., Ltd., Death Module BL4265SN (trade name) (Hereinafter referred to as IPDI), "Death module BL1265MPA / X (trade name)" (hereinafter referred to as TDI), and "Duranate E402-B80T" (hereinafter referred to as HDI 2) manufactured by Asahi Kasei Chemical Co., Ltd. were used.

As a bright pigment, aluminum flake "Aluminum paste CR-9800RM" (brand name) made by Asahi Kasei Metals Co., Ltd. (average particle diameter 8 micrometers), aluminum flake "lu paste 7220NS (brand name) made by Toyo Alumina Corporation" (average particle diameter 25 micrometers) Was used.

As the wax used as the comparative material, a commercially available microcrystalline wax was used.

In addition, the diluting solvent used the thing which mixed cyclohexanone: sorbet 150 = 1: 1 by mass ratio.

Next, the intermediate coating material used in the experiment is explained in detail.

As the base resin, "Byron (registered trademark) GK140" (glass transition temperature 20 ° C), "Byron (registered trademark) GK360" (glass transition temperature 36 ° C) and "Byron (registered), which are amorphous polyester resins manufactured by Toyobosha Trademark) GK110 "(glass transition temperature 50 degreeC) and" Byron (registered trademark) 660 "(glass transition temperature 55 degreeC) were used. As needed, it mixed and adjusted and used the glass transition temperature of resin. As the crosslinking agent, "Super Bectamine (registered trademark) J830", which is a butylated melamine resin (hereinafter referred to as butylated melamine) manufactured by Dainippon Ink & Chemical Co., Ltd., was used. As the coloring pigment, commercially available aluminum flakes are used for silver pigments, carbon blacks are commercially available for black pigments, titanium oxide commercially available for white pigments, and red iron oxide commercially available for red pigments. Used. In addition, the solvent mixed with cyclohexanone: sorbet 150 = 1: 1 by mass ratio was used.

The detail of the produced top coating material and intermediate coating material is described in Table 2, Table 2-2, and Table 3, respectively. In addition, the glass transition temperature of the coating film was the thermomechanical analyzer "SSC5200 series TMA / SS120C" by Seiko Denshisha, The probe at the time of the measurement was measured using the probe with a needle.

TABLE 1

TABLE 2

Table 2-2

[Table 3]

In addition, a clear paint of FL641EU primer, a polyester primer for PCM manufactured by Nippon Fine Co., Ltd., was prepared, and `` K-WHITE # 105 '' was cleared with tripolyphosphoric dihydrogen aluminum made by Teikasha, a chromate-free rust preventive pigment. The chromate pre primer was created by adding 30 mass parts with respect to 100 mass parts of solid content of coating material.

Hereinafter, the precoat metal plate used for the experiment of an Example is demonstrated in detail.

A hot-dip galvanized steel plate "Silver Zinc (registered trademark)" (hereinafter, referred to as GI) manufactured by Shin-Nichi Seitetsu Co., Ltd. was prepared as an original. The plate thickness used what is 0.6 mm. The plating adhesion amount used the single side | surface 60 mg / m <2>.

Next, the prepared original was spray-degreased with a 2 mass% concentration of alkaline degreasing liquid "FC-4336" made by Nippon Parka Co., Ltd., a 50 degreeC aqueous solution, washed with water, and after drying, it was chromate-free chemical conversion treatment made by Nippon Parka Co., Ltd. "CT-E300N" was applied by a roll coater and dried in a hot air oven. Drying conditions in a hot air oven made the reaching plate temperature of a steel plate 60 degreeC. The coating amount of the chromate-free treatment was applied so as to adhere 200 g / m 2 at all solid contents.

Next, on one side of the metal plate subjected to the chemical conversion treatment, the produced primer paint was coated on the other side with a roll coater coated with a gray color of “FL100HQ”, which is a backside paint, and the metal plate was heated by an induction heating furnace in which hot air was blown. It was dry-hardened on the conditions which reach | attain plate plate temperature of 210 degreeC. And after dry baking, water was sprayed on the coated metal plate by spraying, and water cooled.

Next, on the primer coating film, the intermediate coating paint and the top coating were simultaneously laminated in two layers with a slide hopper type curtain coater, and under the condition that the reaching plate temperature of the metal plate was 230 ° C by an induction heating furnace in which hot air was blown. The laminated coating film was dried and cured simultaneously. After the dry baking, water was sprayed onto the coated metal plate by spraying and water cooled to prepare a three-layer precoat metal plate (hereinafter, the present coating method is referred to as "painting method (i)").

In addition, only one layer of the intermediate coating material was coated on the primer coating film by a roller curtain coater on the primer coating film, and the top coating material was coated on the coating film by the roller curtain coater before drying it again, and the coating film was dried and cured at the same time. After drying and baking, water was sprayed onto the coated metal plate by spraying and water-cooled to produce three layers of precoat metal plates (hereinafter, the present coating method is referred to as "painting method (ii)").

Furthermore, after coating only one layer of the intermediate coating material with a roll coater on the primer coating film, and baking the above-described method, the three-layer precoat metal plate which is baked by baking a single layer of the top coating with a roll coater on the intermediate coating film again. (The coating method in this procedure is called "painting method.").

In addition, the intermediate coating material, the intermediate coating material, and the top coating material were simultaneously laminated on three layers by a slide hopper type curtain coater on the primer coating film, and the reaching plate temperature of the metal plate was 230 ° C by an induction heating furnace in which hot air was blown. The laminated coating film was dried and cured at the same time. After the dry baking, water was sprayed onto the coated metal plate by spraying and water cooled to prepare a four-layer precoat metal plate (hereinafter, the present coating method is referred to as "painting method").

In addition, only one layer of the intermediate coating material is coated on the primer coating film by a roll coater, and then baked, and the intermediate coating material is coated on the intermediate coating film by one layer with a roll coater, and then baked and sawed by the roll coater on the intermediate coating film again. A four-layer precoat metal plate was also produced by coating the paint one layer and baking (the coating method in this procedure is referred to as "painting method (v)").

Hereinafter, the detail of the evaluation method of the precoat metal plate produced by the experiment is described.

1. Universal Hardness

It measured using the micro hardness tester "Fisher Scope (registered trademark) H100" by a Fisher Insulations Corporation. The atmospheric temperature at the time of measurement was set to 23 degreeC, and the universal hardness [HU (N / mm <2>)] was measured on condition that the Vickers indenter of surface angle 136 degrees 4 pyramids will be 5 mN of press loads for 60 second.

2. Lubricity

Using HEIDON-14, the force F applied when a stainless steel ball (10 mm ø) was moved 110 mm in parallel on a precoated metal sheet under 100 g load and 150 mm / min was measured, and the average friction coefficient was measured. Calculated. In addition, the measurement site | part was made into five places within the range of 100 mm except the initial 10 mm.

3. Measurement of mirror glossiness of coating film of precoat metal sheet

The specular glossiness was measured on the conditions which the incident angle and the light-receiving angle are 20 degrees using the "digital variable angle glossmeter" by Suga Shikekisha. The 20 degree glossiness of the primary reference plate (No. 99B076) made by Suga Shikekisha was 88%, and it adjusted so that the 20 degree glossiness of the secondary reference plate (No. 99W076) might be 15%.

4. Damage resistance test

Using HEIDON-14, the 10 yen coin is brought into contact with the precoat metal plate at 45 °, and the load is applied in the vertical direction,

The presence or absence of the scratch at the time of moving the precoat metal plate 1 round trip at 50 mm / min in a horizontal direction was visually judged, and it evaluated by the maximum load which a scratch did not generate | occur | produce.

○: 50 g or more

△: 20 g or more but less than 50 g

×: less than 20 g

Pencil hardness

According to the method of 8.4.1 (1993) of JIS-K 5400, the scratch resistance of the coating film is irradiated with the scratches of the coating film when the hardness of the pencil core is changed, and the coating film has the highest hardness at which the scratches on the coating film are not recognized. It was set as the pencil hardness of and evaluated as follows.

○: H or more, △: 3B or more and less than H, ×: 4B

5. Coating processability test

The produced precoat metal plate was bent 180 degrees (close bending), and the coating film of the processed part was visually observed, and the presence or absence of cracking of the coating film was examined. Moreover, when performing 180 degree bending, the surface of the precoat metal plate was bent so that it might be outside of a bending, and close bending was performed (generally known as 0T bending). Then, the process is visually observed to indicate that there is no coating film cracking or peeling at all, o when the film is slightly cracked or peeled off, and △, when the coating film has cracks or peeling reaching the primer coating film or metal plate. Evaluated. Moreover, the process part adhesiveness test which affixes and peels a tape to a process part is also performed, and when the adhesiveness after tape peeling is observed visually, and clear peeling is not recognized by a coating film, the total is half with respect to the total length of a bending process part. When the coating film peeling was recognized by less than the length, the case where coating film peeling was recognized by length more than half with respect to the total length of (triangle | delta) and a bending process part was evaluated as x.

6. Color value

L value was measured with the spectrophotometer (former MSC-45-2B by the Suga company) according to JIS 를 Z # 8722.

7. Storage stability of paint

200g of paint was put into the paint container (1 liter, outer diameter (phi) 112mm, height 130mm), the lid was covered, it stored at 40 degreeC, and the presence or absence of gelation of the paint was investigated. (Circle) and what gelled in (triangle | delta) and the thing which gelled in (triangle | delta) and 0 to 3 months were what did not gel in 6 months, and were x. In addition, the paint container was turned upside down, and gelling was carried out in a state in which the paint did not leak to the outside even after being left to stand for 1 hour.

8. Thickening resistance of paint

200g of paint was put in the paint container (1 liter, outer diameter (phi) 112mm, height 130mm), the lid was covered, it was stored at 50 degreeC for 1 hour, and the thickening resistance of the paint was investigated.

The viscosity was adjusted to 20 degreeC, and it filled into the Iwata cup, and measured the number of seconds until the whole quantity flowed out using a stopwatch. The value obtained by dividing the number of seconds of the coating material after storage (the number of seconds measured by the Iwata cup) by the viscosity of the coating material before the storage was less than 1.5.

9. Measurement of Interface Ra

The interface Ra between the intermediate coating layer and the initial coating layer is 3500 times by smoothing the cross section perpendicular to the surface of the coating film by cutting the coating film of each example in the vertical direction with respect to the coating direction, embedding in resin, and then polishing. It evaluated by the photograph photographed with the scanning microscope of. After the transparent sheet used for OHP was covered from the photograph, and the irregularities of the boundary surface were precisely traced, as shown in the figure, the area of the vertical line portion was measured with an image processing apparatus, and Ra was calculated from the equation as the average value. . In addition, l (L) was 3 mm.

[Equation 1]

Hereinafter, the evaluation result is described in detail.

Tables 4-7 show the precoat metal plate produced by this invention and its evaluation result. Moreover, although the effect of this invention is demonstrated using the test-providing material which performed the primer coating film, even when a primer coating film is not performed, the same performance as the primer coating film is obtained.

(1) Influence of average friction coefficient and universal hardness

As an influence of an average friction coefficient and universal hardness, an Example is shown to 1-19 and a comparative example is shown to 20-28.

The precoat metal plate (1st-19th Example) of this invention had the outstanding damage resistance, gloss, and workability.

The average friction coefficient exceeding 0.08 (the 22nd and 25th comparative examples) is not suitable because the damage resistance is poor. The thing with universal hardness less than 75 N / mm <2> (compared to 20th and 26th examples) is unsuitable because it is inferior to damage resistance. The thing with the universal hardness exceeding 200 N / mm <2> (21st and 27th comparative examples) is unsuitable since it is inferior to workability.

(2) Influence of the top coating film type and the intermediate coating film type

The top coating layer is a clear coating film which does not contain a pigment, content of the silicone graft acrylic resin in a top coating film is 2-18 mass% in conversion of silicone resin, an intermediate coating film layer contains a coloring pigment, and a melamine cured type or an isocyanate cured type Containing a polyester resin, the glass transition temperature of an intermediate coating film is 25-50 degreeC, the glass transition temperature of a top coating film is 30-67 degreeC, and the ratio of the silicone resin in a silicone graft acrylic resin is 3-20 mass. Containing a silicone graft acrylic resin of%, the intermediate coating film layer contains a colored pigment, contains a melamine cured or isocyanate cured polyester resin, and has a glass transition temperature of 25 to 50 ° C. Examples 1 to 19 had excellent damage resistance, gloss and workability. The content of the silicone graft acrylic resin in the top coating film exceeds 18 mass% in terms of silicone resin (Examples 20 and 21), and the ratio of the silicone resin in the silicone graft acrylic resin exceeds 20 mass% (the Example 21) tended to have a relatively low storage stability of the paint.

When the glass transition temperature of the top coating layer is less than 30 ° C (22nd comparative example), and the glass transition temperature of the intermediate coating film is less than 25 ° C (26th comparative example), the universal hardness tends to be lowered and damage resistance Fall, content of silicone graft acrylic resin in top coating film being less than 2 mass% in conversion of silicone resin (24th and 25th comparative example), and ratio of silicone resin in silicone graft acrylic resin being less than 3 mass% (24th In Comparative Example), the dynamic friction coefficient tended to be lowered, and the damage resistance was inferior.

The glass transition temperature of a top coat layer exceeding 67 degreeC (23rd comparative example), and the glass transition temperature of an intermediate coating film exceeding 50 degreeC (27th comparative example) tend to have too high universal hardness. There was, and workability was inferior.

Adding a large amount of wax to the top coating layer and obtaining a universal hardness of 75 N / mm 2 or more and an average friction coefficient of 0.08 or less (Comparative Example 28) is unsuitable because the glossiness of the mirror is less than 50%.

(3) Influence of the film thickness

When the film thickness of the top coating layer was 0.5 µm (Example 29), the lubricity was slightly decreased, and the damage resistance was slightly inferior. The thing whose film thickness of the top coating layer was 12 micrometers (Example 35) had a tendency for the workability to fall slightly. As for the film thickness of a top coating film layer, 1-10 micrometers is more preferable.

When the film thickness of the intermediate | middle application coat layer was 3 micrometers (Example 36), L value became a little high and it was a tendency for black to become difficult to come out. When the film thickness of the intermediate | middle coating film layer was 22 micrometers (Example 43), hardness fell slightly and the damage resistance tended to fall. As for the film thickness of an intermediate coating film layer, 5-20 micrometers is more preferable.

(4) Influence of coloring kind of intermediate coating film layer

In addition to the present invention, damage resistance is satisfied in light colors such as white and silver, but scratches cannot be prevented in deep colors such as black and red (Comparative Examples 48 to 51). On the other hand, it can be seen that the invention of the present invention has good damage resistance and excellent damage resistance performance not only in light colors but also in deep colors (Examples 44 to 47).

In addition, the performance (glossy and workability) other than a damage resistance shows favorable performance in both a comparative example and this invention, regardless of the color of an intermediate coating film layer.

(5) Influence of coating method

Coating and baking of the intermediate coating layer and the top layer one by one (Example 54) tended to reduce workability and adhesion as compared with those produced by multilayer simultaneous coating and wet on wet coating. From this result, it turns out that the thing manufactured by multilayer simultaneous application | coating and wet-on-wet coating improves workability and adhesiveness, and is more suitable.

(6) Influence of Brightness Pigment

The influence of the bright pigment is shown in Table A. It was a tendency for a pencil hardness to improve that a top coat layer contains a bright pigment (Example 57-60th Example), since a scratch becomes hard to be outstanding.

(7) Influence of crosslinking agent type

The effect of the type of crosslinker is shown in Table B. The use of an isocyanate compound as the crosslinking agent (Examples 63 to 77) tended to be more excellent in the thickening resistance of the top coating material. It can be seen that the molar ratio of NCO / OH is 0.05 to 0.3 / 1.0 (68th to 70th Examples) with higher scratches, which is more suitable.

(8) On the provision of wear resistance

Table C shows the provision of wear resistance. When the hardness at 23 ° C. on the surface of the coating layer was set to 150 to 200 N / mm 2 at a universal hardness under a 5 mN load (Examples 80 to 88), a high wear resistance tended to be provided.

As an isocyanate compound, isophorone diisocyanate (IPDI) was used, and the molar ratio of NCO / OH was 0.1-0.5 / 1.0 (Example 82, 85, 86 Examples) tended to be excellent in wear resistance.

(9) Effect of interface Ra between intermediate coating layer and top layer

Table D shows the effect of the interface Ra between the intermediate coating layer and the top layer. The interface Ra between the intermediate coating layer and the top layer is 0.3 to 0.8 (Examples 89, 91, 93, 95, 97, 99, 101, 103, 105, and 107), and the workability and adhesion are improved and more suitable. Able to know.

(10) Influence of the intermediate coating layer

Table E shows the influence of the intermediate coating layer. Containing a bright pigment in the intermediate coating layer (Examples 109 to 128) tended to improve pencil hardness by making scratches less noticeable.

(11) Influence of Interface Ra between Intermediate Coating Layer and Top Layer

Table D shows the effect of the interface Ra between the intermediate coating layer and the top layer. It can be seen that the interface Ra between the intermediate coating layer and the top layer is 0.3 to 0.8 (Examples 109 to 118), workability and adhesion are improved, and more suitable.

[Table 4]

TABLE 5

TABLE 6

TABLE 7

TABLE A

TABLE B

TABLE C

TABLE D

TABLE E

As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to this example. It is apparent to those skilled in the art that various changes or modifications can be conceived within the scope described in the claims, and that they naturally belong to the technical scope of the present invention.

Claims (18)

It is a precoat metal plate which has a coating film layer in the one or both surfaces of a metal plate,
The said coating film layer has at least the top coating film layer which is the coating film formed in the outermost surface, and the intermediate coating film layer which is a lower coating film which contact | connects the said top coating film layer,
The top coating layer is a clear coating film containing a silicone graft acrylic resin and not containing a pigment, and the intermediate coating film layer is a coating film containing a melamine cured or isocyanate cured polyester resin and containing a colored pigment. ,
The average coefficient of friction of the coating layer surface of the coating layer is 0.08 or less, the hardness at 23 ° C. of the coating layer surface is 75 to 200 N / mm 2 in universal hardness under 5 mN load, and the mirror surface glossiness of the coating layer surface The incidence angle and the light reception angle are each 50% or more when measured on the conditions of 20 degrees, The precoat metal plate characterized by the above-mentioned. It is a precoat metal plate which has a coating film layer in the one or both surfaces of a metal plate,
The said coating film layer has at least the top coating film layer which is the coating film formed in the outermost surface, and the intermediate coating film layer which is a lower coating film which contact | connects the said top coating film layer,
The top coating layer is a clear coating film containing a silicone graft acrylic resin and further containing a pigment, the intermediate coating film layer is a coating film containing a melamine curable or isocyanate curable polyester resin and further containing a colored pigment,
The average coefficient of friction of the coating layer surface of the coating layer is 0.08 or less, the hardness at 23 ° C. of the coating layer surface is 75 to 200 N / mm 2 in universal hardness under 5 mN load, and the mirror surface glossiness of the coating layer surface The incidence angle and the light reception angle are each 50% or more when measured on the conditions of 20 degrees, The precoat metal plate characterized by the above-mentioned. The precoat metal plate of Claim 2 whose said top coating layer is a clear coating film containing a bright pigment. The precoat metal plate of Claim 1 or 2 whose said top coat layer is a melamine hardening type. The precoat metal plate of Claim 1 or 2 whose said top coat layer is an isocyanate hardening type. The precoat metal plate according to claim 5, wherein in the isocyanate curable top coating layer, the ratio of NCO / OH is 0.05 to 0.5. The precoat metal plate according to any one of claims 1 to 6, wherein Ra (center line average roughness) of the interface between the top coating layer and the intermediate coating layer is 0.3 to 0.8. Content of the silicone graft acrylic resin in the said top coating film is 2-18 mass% in conversion of silicone resin, The precoat metal plate in any one of Claims 1-7 characterized by the above-mentioned. The glass transition temperature of the said top coating film is 30-67 degreeC, and the ratio of the silicone resin in the silicone graft acrylic resin contained in the said top coating film is 3-20 mass%. And the glass transition temperature of said intermediate coating film is 25-50 degreeC, The precoat metal plate characterized by the above-mentioned. The precoat metal plate according to any one of claims 1 to 8, wherein the hardness at 23 ° C of the coating layer surface is 150 to 200 N / mm 2 in universal hardness under a 5 mN load. The precoat metal plate of Claim 10 or 11 whose said top coat layer is an isocyanate hardening type. The precoat metal plate of Claim 11 whose hardening | curing agent in the said top coat layer is isophorone diisocyanate (IPDI). The precoat metal plate of Claim 11 or 12 whose ratio of the hardening | curing agent in the said top coat layer is 0.1-0.5. It is a precoat metal plate which has a coating film layer in the one or both surfaces of a metal plate,
The coating layer has at least a top coating layer, which is a coating film formed on the outermost surface, an intermediate layer in contact with the top coating layer, and an intermediate coating film layer, which is an undercoat in contact with the intermediate coating layer,
The top coating layer is a clear coating film containing a silicone graft acrylic resin and not containing a pigment, and the intermediate coating film layer is a coating film containing a melamine cured or isocyanate cured polyester resin and containing a colored pigment. ,
The average coefficient of friction of the coating layer surface of the coating layer is 0.08 or less, the hardness at 23 ° C. of the coating layer surface is 75 to 200 N / mm 2 in universal hardness under 5 mN load, and the mirror surface glossiness of the coating layer surface The incidence angle and the light reception angle are each 50% or more when measured on the conditions of 20 degrees, The precoat metal plate characterized by the above-mentioned. The precoat metal plate according to claim 14, wherein the intermediate layer contains a pigment. The precoat metal plate according to claim 15, wherein the intermediate layer contains a bright pigment. The precoat metal plate according to any one of claims 14 to 16, wherein Ra (center line average roughness) at the interface between the top coating layer and the intermediate layer is 0.3 to 0.8. It is a manufacturing method of the precoat metal plate of any one of Claims 1-17,
A method of producing a precoated metal sheet, wherein the intermediate coating film layer and the top coat layer are coated with a multilayer simultaneous coating or a wet on wet method, respectively, and then baked.

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