JP2945648B2 - Decorative painted metal sheet and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a design-coated metal plate (pre-coated steel plate) commonly used in household electric appliances and the like, and more particularly, to a low gloss having a maximum value of 10 or less at any light receiving angle. The present invention relates to a decorative painted metal plate provided with a so-called fine pattern having gloss. The metal sheet of the present invention is not limited to aluminum sheets and copper sheets, and various steel sheets such as cold-rolled steel sheets, hot-dip galvanized steel sheets, electro-galvanized steel sheets, galvannealed steel sheets, stainless steel sheets, copper-plated steel sheets, tin-plated steel sheets, and the like. Applied to In the following description, a steel sheet will be mainly described as a typical example, but the present invention is not limited to this.

[0002]

2. Description of the Related Art A coated steel sheet obtained by applying a spray coating, an electrodeposition coating, a powder coating or the like to a zinc-coated steel sheet has been widely used for household electric appliances. However, in recent years, pre-coated steel sheets for the purpose of omitting the painting process in home appliance manufacturers have become popular.

[0003] For home electric appliances such as VTRs and audios, pre-coated steel sheets having a sense of depth and calm have been demanded, and low gloss steel sheets having low gloss have been proposed in order to satisfy such required characteristics. In general, methods for reducing the gloss of the coating film include increasing the pigment concentration in the paint, adding a filler such as beads, and further adding a matting agent such as silicic acid fine powder. The method is adopted.

For example, Japanese Patent Application Laid-Open No. 63-158246 discloses a low gloss coated steel sheet in which various inorganic powders and hardened resin powders are added in predetermined amounts to a film forming component. According to this method, the glossiness at a certain angle can be lowered, but if the angle is changed variously, the glossiness changes greatly, and the glossiness increases depending on the viewing angle. However, it cannot be said that the required characteristics have been sufficiently satisfied.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to reduce the variation in gloss and reduce the gloss even when the angle is variously changed. It is an object of the present invention to provide a design-coated metal plate provided with a so-called fine pattern, which satisfies the maximum value of the glossiness of 10 or less), and a method capable of efficiently producing such a metal plate.

[0006]

The design-coated metal sheet of the present invention, which has achieved the above-mentioned objects, has a maximum value of 60 ° specular gloss of 10 or less and is obtained by the following equation (1). The point is that the standard deviation σ is 1.5 or less.

[0007]

(Equation 2)

[0008] The coated metal plate of the present invention satisfying such requirements is provided with a so-called crepe pattern.

Further, the production method of the present invention which can solve the above-mentioned problems is characterized in that a heat-sensitive cross-linking agent whose cross-linking expression temperature differs by 30 ° C. or more is used.
Seeds are used (the baking temperature is preferably higher than any of the cross-linking expression temperatures of the heat-sensitive cross-linking agent used).
Alternatively, the gist is that a cross-linking catalyst blocked with a volatile blocking agent is used.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, all of the conventional "low-gloss coated steel sheets" have a reduced glossiness at a certain angle, and the glossiness changes when the angle is changed. No consideration is given to the fact that it will grow. That is, the glossiness is generally measured at 60 ° specular glossiness (incident angle 60 °, light receiving angle 60 °), and it is known that the glossiness at the light receiving angle is 10 or less. Various changes change the glossiness, and the glossiness greatly changes depending on the light receiving angle. Accordingly, a steel sheet having a “depth and calmness” cannot be obtained with this method, and it cannot be said that the steel sheet sufficiently satisfies desired required characteristics.

The inventors of the present invention have conducted intensive studies to provide a coated steel sheet (a steel sheet provided with a so-called crumpled pattern) having a small gloss and a small variation even when the light receiving angle is variously changed. If a steel sheet is manufactured using a predetermined heat-sensitive crosslinking agent or a crosslinking catalyst, light can be scattered at any angle, and it has been found that the intended purpose is achieved brilliantly. is there.

That is, the decorative coated metal plate of the present invention has a size of 60
The maximum value of the glossiness measured with respect to the incident angle of ゜ is 10 or less, and the standard deviation σ obtained by the above equation (1) satisfies 1.5 or less.

More specifically, a gloss meter VGS-II manufactured by Nippon Denshoku Co., Ltd.
When the glossiness is measured by the method shown in FIG. 1 using 90, the maximum value of 60 ° specular glossiness is 10 or less, and the standard deviation σ obtained by the above equation (1) satisfies 1.5 or less. Is what you do. This means that when the incident angle is set to 60 ° and the light receiving angle is variously changed in the range of 50 to 75 ° and the glossiness is measured at 5 ° intervals, the glossiness is as small as 10 or less even if the glossiness is maximized. In addition, the standard deviation of the glossiness in the range of the light receiving angle is 1.5 or less, which means that the variation can be suppressed low.

To clarify this, FIG. 2 is a graph showing a part of the embodiment described later. FIG.
7 is a plot of the glossiness at each light receiving angle when changed in the range of up to 75 °. Both the present invention example and the conventional example show the same behavior up to a light receiving angle of around 0 ° to 50 °, but the difference between them becomes clear above 50 °. That is, in the examples of the present invention (○ and Δ in the figure), the maximum value of the gloss was 10
(The light receiving angle is around 60 °), and the standard deviation σ represented by the above equation (1) is as small as 1.5 or less, whereas in the conventional example (□ in the figure), the gloss becomes near 60 °. The degree becomes very high and the maximum value exceeds 10. Further, in another conventional example (（in the figure), the maximum value of the glossiness is suppressed to 10 or less, but the glossiness changes greatly near the light receiving angle of 60 ° (around 60 ° ± 10 °), and the glossiness changes. The variation becomes extremely large. Next, a method for manufacturing such a metal plate of the present invention will be described.

Although the present invention is provided with a so-called crepe pattern which can scatter light at any angle as described above, basically, the surface of the coating film is cured before the inside of the coating film is cured. Obtained by: That is, by providing a difference in the curing speed between the coating film surface and the inside, it is intended to impart an arbitrary fine pattern, the surface layer cures and contracts in the early stage of curing, and the contraction distortion of the lower layer in the later stage of curing causes the surface layer to contract. The absorption of the particles gives the surface a blemishes.

As described above, according to the method of the present invention, the most important point is that a predetermined additive is added to a coating film so that a predetermined shrinkage pattern can be obtained. Can be used.

Method of using two types of heat-sensitive cross-linking agents whose cross-linking expression temperatures differ by 30 ° C. or more The heat-sensitive cross-linking agent comprises a cross-linking component (isocyanates) and a blocking agent (alcohols, phenols, ε-caprolactam, etc.). ). This cross-linking agent is inactive in a blocked state, but when heated by a hot air oven or the like, the blocking agent is dissociated, and the cross-linking component is activated to cause a cross-linking reaction with the base resin. Two kinds of heat-sensitive cross-linking agents having different cross-linking temperature (cross-linking temperature (Tb) and high-temperature dissociating cross-linking agent (cross-linking temperature Ta)) can be added to the coating film. For example, by heating, first, the low-temperature dissociation type cross-linking agent moves to the coating film surface, and the blocking agent among them dissociates to activate the cross-linking component, thereby forming a so-called shrinking pattern.

The temperature at which the crosslinking property is exhibited can be varied depending on the type of the blocking agent used. To provide a shrink pattern, the temperature difference must be 30 ° C. or more (Tb-Ta).
≧ 30 ° C.). The temperature difference is preferably as large as possible. However, if the temperature difference is too large, so-called coating defects (defects generated when the solvent in the coating material evaporates in a state where the coating is formed on the surface of the coating film). Considering that the occurrence of cracks easily occurs, it is recommended that the temperature be 60 ° C. or lower.

The total content of the low-temperature dissociative crosslinking agent and the high-temperature dissociative crosslinking agent in the coating film is preferably 3 to 30 parts by weight based on 100 parts by weight of the resin. If the content exceeds 30 parts by weight, the crosslink density of the coating film increases, and the elongation of the coating film decreases, which is not preferable for a precoated metal sheet that requires processing after forming the coating film. More preferably 2
0 parts by weight or less. On the other hand, if the content is less than 3 parts by weight, the effect of the addition by the crosslinking agent is small, and the desired shrinking effect cannot be obtained. It is more preferably at least 5 parts by weight.
In addition, it is recommended that these ratios are set as low-temperature dissociation type crosslinking agent: high-temperature dissociation type crosslinking agent = 3-7: 7-3.

The baking temperature is preferably higher than the cross-linking temperature (Tb) of the high-temperature dissociation type cross-linking agent, whereby a desired shrink pattern can be efficiently obtained. More preferably, it is recommended to raise the temperature by 10 ° C. or more.

Method Using a Crosslinking Catalyst Blocked with a Volatile Blocking Agent The above crosslinking catalyst comprises a volatile blocking agent (amine) and a catalyst component (sulfonic acid). This cross-linking catalyst is inactive when it is blocked, but when heated by a hot air oven or the like, the blocking agent is dissociated, and the volatilized blocking agent is discharged out of the system by hot air, while the activated catalyst component is The cross-linking reaction between the base resin and the cross-linking agent is promoted, and consequently, a shrinking pattern is provided.

The crosslinking catalyst is preferably added in an amount of 0.1 to 1.5 parts by weight per 100 parts by weight of the resin in the coating film. If it exceeds 1.5 parts by weight, a large amount of catalyst is added,
Crosslinking occurs not only in the surface layer of the coating film but also in the inner layer portion, so that a desired fine appearance cannot be obtained. On the other hand, if it is less than 0.1 part by weight, the effect of the catalyst is insufficient, and the desired fine appearance cannot be obtained.

The cross-linking agent used in the above method is not particularly limited as long as it is used for ordinary precoated steel sheets, and examples thereof include melamine resins.

As described above, according to the method of the present invention, the above-mentioned or the above-mentioned additives are essentially contained in the coating film, but the wax, aggregate, pigment, defoamer and the like can be used as long as the action of the present invention is not impaired. Agents, leveling agents, metal pieces such as aluminum and the like can be added.

The coating resin used in the coating film of the present invention is not particularly limited as long as it can use a crosslinking agent. Epoxy, polyester, acrylic, melamine, urethane, silicone and the like. Solvent-dilutable paints such as acrylic-styrene, epoxy-ester, acrylic, urethane, polyvinyl acetate, polyethylene, and ethylene vinyl acetate paints. These may be used alone or in combination of two or more.

In producing the steel sheet of the present invention, a paint containing the above or the above-mentioned additives is applied to a base metal plate and baked to form a coating film. For application, a method used for a normal pre-coated metal plate can be adopted, and examples thereof include a roll coater method and a curtain flow method.

Hereinafter, the present invention will be described in detail with reference to examples.
However, the following examples do not limit the present invention,
All modifications and alterations without departing from the spirit of the preceding and following descriptions are included in the technical scope of the present invention.

[0028]

Example 1 A chromate-treated galvanized steel sheet coated with a primer
Various paint components (A to J) shown in Tables 1 and 2 were
The dry weight of the coating film is 30 g / m ^Two Becomes
I did it. After that, at a temperature of 230 ° C in a hot air oven, 60
Each sample was obtained by baking for 2 seconds. The above coating
The ingredients A to J are all polyester resins as base resins.
The resin is used.

In each of the thus obtained test materials, 6
The 0 ° specular gloss was measured by the above method, the standard deviation of the gloss represented by σ was calculated, and the design was evaluated by the following method.

[Design Evaluation Method] The appearance of the test material was visually observed and evaluated according to the following criteria. ：: A matte appearance (matte appearance) is obtained even from all angles. Δ: The gloss is conspicuous when viewed from a specific angle, and a matte appearance cannot be obtained. ×: The gloss is very conspicuous, and the appearance is not matte. The results are shown in Tables 1 and 2.

[0031]

[Table 1]

[0032]

[Table 2]

The following can be considered from the table.
First, A and B are examples of the present invention using two types of heat-sensitive crosslinking agents having different cross-linking development temperatures, and satisfy a gloss (G ₆₀ ) at 60 ° of 10 or less and a σ of 1.5 or less. And it has excellent design.

On the other hand, C is an example using only a low-temperature dissociation type crosslinking agent, and D is an example using only a high-temperature dissociation type crosslinking agent.
G ₆₀ is as high as 55 or more, σ also increases,
When viewed from a specific angle, the gloss is conspicuous and the design is inferior.

[0035] Then, E to G is the invention example using both the crosslinking agent crosslinking catalyst, F is but one in which further also added beads, in any case, G ₆₀ 10 or less, sigma
It satisfies 1.5 or less and has excellent design.

The conventional hand I and J without adding a crosslinking catalyst is added only crosslinking agent and beads, H but is a conventional example of adding only the cross-linking agent, both G _60, sigma is large Inferior in design. This tendency was particularly remarkable in H.

Example 2 Next, with respect to the coating material component A, the design property was similarly evaluated using two types of heat-sensitive crosslinking agents having variously changed crosslinking developing temperatures. Table 3 shows the obtained results.

[0038]

[Table 3]

Nos. 1 to 3 are examples of the present invention in which heat-sensitive cross-linking agents differing in cross-linking temperature by 30 ° C. or more are used, but are excellent in design. On the other hand, Nos. 4 and 5 whose cross-linking temperature does not satisfy the above requirements are inferior in design.

[0040]

Since the decorative coated metal plate of the present invention is constructed as described above, even if the light receiving angle is changed variously, the glossiness is small, and the variation in the gloss is small. The board was obtained efficiently.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a method for measuring glossiness at an incident angle of 60 °.

FIG. 2 is a graph showing the results of Example 1.

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tadashige Nakamoto 1 Kanazawacho, Kakogawa City, Hyogo Prefecture Kobe Steel, Ltd. Kakogawa Works (56) References JP-A-6-316772 (JP, A) JP JP-A-6-278245 (JP, A) JP-A-4-31037 (JP, A) JP-A-9-71750 (JP, A) Table of contents JP-A-5-508434 (JP, A) (58) Fields investigated (Int) .Cl. ⁶ , DB name) B32B 15/08 B05D 7/14

Claims (5)

(57) [Claims] 1. The maximum value of 60 ° specular gloss is 10 or less, and the standard deviation σ obtained by the following equation (1) is 1.5.
A design painted metal plate characterized by the following. (Equation 1) 2. The design-coated metal sheet according to claim 1, wherein the metal sheet is provided with a fine pattern. 3. The method for producing a design-coated metal sheet according to claim 1, wherein two kinds of heat-sensitive crosslinking agents having different crosslinking expression temperatures differing by 30 ° C. or more are used. 4. The production method according to claim 3, wherein the baking temperature is higher than any of the cross-linking expression temperatures of the heat-sensitive crosslinking agent used. 5. The method according to claim 1, wherein a crosslinking catalyst blocked with a volatile blocking agent is used.