JPH0611880B2 - Metallic coating composition for electrostatic coating - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a metallic coating composition for electrostatic coating. More specifically, it is applied to an object to be treated in the same manner as a solid color coating or a clear coating. The present invention relates to a metallic coating composition for electrostatic coating, which enables normal coating and color changing operation without causing electrostatic leakage. The metallic coating composition for electrostatic coating of the present invention is used for coating automobile bodies, for example.

[Prior Art] A conventional metallic coating composition capable of color change operation in a short time without causing electrostatic leakage even when electrostatically coated under high voltage is a solvent containing conductive metal powder or flakes. Type coating composition comprising a predetermined amount of an anti-sedimentation agent and an ionic modifier to adjust the volume resistivity of the coating composition to 1 to 15
There is known one characterized by having MΩ · cm (JP-A-56-84770).

In this coating composition, a method for preventing electrostatic leakage due to a bridging phenomenon of a conductive metal powder such as aluminum when the electrostatic coating voltage is increased is to stop the movement of the metal powder by an anti-precipitation agent and The property adjusting agent controls the volume resistivity of the composition within a certain range. However, the effect of this precipitation inhibitor is a matter of degree and does not completely stop the movement. Furthermore, controlling the volume resistivity of this composition cannot be a fundamental measure against electrostatic leakage. That is, if the resistance value is too low, there is no meaning of electrostatic coating, and if it is too high, bridging is likely to occur, so this coating composition does not solve the problem.

[Problems to be Solved by the Invention] The present invention overcomes the above-mentioned drawbacks, and enables electrostatic-leak-free coating in the same manner as solid color or clear paint and enables a color change operation in a short time. An object of the present invention is to provide a metallic coating composition for electrostatic coating.

[Means for Solving the Problems] The metallic coating composition for electrostatic coating of the present invention is a solvent-based coating composition containing a powdery or flake-like conductive material, and the coating composition is the conductive material. It is characterized by containing 3 to 10 parts by weight of mechanically dispersed fine particles of an organic amine-modified hectorite with respect to 100 parts by weight of the organic material.

The above-mentioned conductive material is a powdery or flake-like material that exhibits conductivity. As this material, for example, a metal powder or a metal flake can be used, and more specifically, a powder or flake such as aluminum, bronze, copper, or a metal vapor-deposited plastic can be used.

These are generally sold in paste form.

The solvent type coating composition is a coating composition using a predetermined solvent.

This coating composition is characterized by containing 3 to 10 parts by weight of an organic amine-modified hectorite with respect to 100 parts by weight of the conductive material. If the blending ratio is less than 3 parts by weight, the effect of preventing electrostatic leakage is insufficient, and if it exceeds 10 parts by weight, problems such as whitening occur in coating film performance, especially in water resistance, which is not preferable.

The organic amine-modified hectorite is a substance in which various amines are attached to the surface of an inorganic compound of hectorite. For example, for this amine Some of these have quaternary amines. Hectorite is a silica (SiO ₂ ) -magnesia (MgO) -based inorganic compound, such as SiO ₂ : 53.95, Al.
₂ O ₃ : 0.14, FeO: 0.03, MgO: 25.
89, CaO: 0.16, K ₂ O: 0.23, Na
₂ O: 3.04, H ₂ O (−): 9.29, H ₂ O
The chemical components of (+): 5.61 and Li ₂ O: 1.22 (each unit is parts by weight) can be included.
This amine-modified hectorite is an organic clay that is amine-modified hectorite by ion-exchange reaction of various quaternary amines and hydrophilic clay.

This amine-modified hectorite differs from amine-modified bentonite in the following points. That is, the bentonite is a silica-alumina type and contains a large amount of Fe ₂ O ₃ , but the hectorite is a silica-MgO type, and the clay structure is generally 100 to 150 (longitudinal) × 1 for amine-modified bendonite.
00-150 (width) x (thickness) shows a size of 8 angstrom, whereas amine-modified hectorite has a size of 100-
150 (length) x 1000-2000 (width) x 8 (thickness)
It is about Angstrom.

Further, it is preferable that the organic amine-modified hectorite is contained in the paste in the form of fine particles dispersed in at least a part of the resin constituting the coating composition. A paste in which the organic amine-modified hectorite is finely dispersed can be blended to obtain a predetermined coating composition.
As this dispersion method, various known methods, for example, a mechanical dispersion method such as a roll mill, a ball mill and a side mill can be used.

In addition, this coating composition includes a resin that has been conventionally used in solvent-based metallic coatings (for example, acrylic resin,
Polyester resin, melamine resin, etc.), solvent (eg toluene, xylene, ethyl acetate, butyl acetate, n
-Butanol, butyl cellosolve, etc.) is contained in a general mixing ratio, and further pigments (e.g., cyanine blue, carbon black, cyanine green, flapansolone, benzimidazolone, perylene, perinone, and the like) as necessary.
Other additives such as titanium oxide, aluminum silicate, iron oxide, quinacridone, etc. and surface modifiers can be added.

[Effect of the Invention] The metallic coating composition for electrostatic coating of the present invention is a solvent-based coating composition containing a powdery or flake-like conductive material, and the coating composition is 100 parts by weight of the conductive material. In contrast, it contains 3 to 10 parts by weight of an organic amine-modified hectorite.

That is, in this coating composition, the quaternary amine on the surface of the modified organic amine-modified hectorite is ionically adsorbed to the adsorbed fatty acid on the surface of the metal pigment to form an insulating coating of the organic hectorite layer on the surface of aluminum. . Therefore, in the present coating composition, since the conductive material is changed to an electric insulator, it is possible to perform coating without electrostatic leakage in the same manner as solid color coating or clear coating, and it is also possible to perform color changing operation in a short time.

Further, as a known method of using this conductive material as an electric insulator, a method of coating the surface of this conductive material with a resin is known. However, this method is not preferable because there is a problem that the finished appearance is blackened compared to the untreated one. On the other hand, when the organic amine-modified hectorite is used, no influence on the finish appearance is observed.

[Examples] The present invention will be described below with reference to Examples.

Example 1 10 parts by weight of organic amine-modified hectorite (hereinafter, “parts” means “parts by weight”) was added to “Acridic 47-712”.
(Dainippon Ink and Chemicals, Inc. acrylic resin, solid content 50% by weight) 126 parts and "Super Beckamine L-
121-60 "(melamine resin manufactured by Dainippon Ink and Chemicals, Inc., solid content 60% by weight) was mixed with a gold spatula for 4 passes with a three-roll mill to obtain a dispersion paste. In addition, xylol /
An n-butanol = 4/1 composition was added to prepare an organic hectorite paste having a solid content of 50% by weight.

On the other hand, 5 parts of "Alpaste 7130N" (aluminum paste manufactured by Toyo Aluminum Co., Ltd., solid content: 65% by weight) was dispersed in 3 parts of xylol, and 28 parts of the above acrylic resin,
While stirring and mixing with 10 parts of the melamine resin using a dispa, 4 parts of the above organic hectorite paste was added and further stirred for 10 minutes using a dispa.

The base paint prepared in this way was further mixed with toluene 1
5 parts, 30 parts of ethyl acetate, and 5 parts of "Ipsol 150" (aromatic hydrocarbon solvent manufactured by Idemitsu Petroleum Co., Ltd.) were diluted to prepare a paintable coating composition (Example 1).

The composition of this coating composition is shown in Table 1.

Using this coating composition, an electrostatic leak test was conducted under the following conditions. As conditions for this, the electrostatic coating device was capable of applying up to 60 KV to the tip of the gun, a metal joint was provided between the gun and the metallic valve, and the length of the paint hose between the metal joint and the gun was set to 15 cm. The metal joint was connected by a lead wire to a pen recorder with a resistance of 1 KΩ so that the current value could be measured.

The current value is stable in a certain range when there is no electrostatic leakage after application, but when electrostatic leakage occurs, the current value suddenly increases and shows an abnormal current value. The coating composition used in the test was filled up to the gun tip of the electrostatic coating device, and the electrostatic leakage property was judged by a method of repeating ON / OFF of the set applied voltage at 5 second intervals while supplying the coating material for 40 seconds.

As a judgment criterion, ○ means that it does not leak to the end, that is, 4
No leak until 0 seconds, △ does not leak until 25 seconds, △ ~ × does not leak until 15 seconds, × is 5
The one that leaks at the second stage is shown in Table 2.

Examples 2 to 4 Using the same raw materials as in Example 1 above and using the same method,
The coating compositions shown in the table were prepared. An electrostatic leak test of this coating composition was also conducted in the same manner as in Example 1 and the results are shown in Table 2.

Comparative Examples 1 to 4 Comparative Example 1 contains no organic hectorite paste,
Comparative Example 2 contains 1 part by weight of the organic hectorite paste, Comparative Examples 3 and 4 contain the organic bentonite paste and no organic hectorite paste, and the other composition components are the same as in Example 1. And Example 1
A coating composition having the composition ratio shown in Table 1 was prepared using the same method as in Example 1, and the performance evaluation was performed in the same manner as in Example 1. The results are shown in Table 2.

Performance Evaluation According to the performance evaluation results of Table 2 in the coating compositions of Examples 1 to 4 and Comparative Examples 1 to 4, Examples 1 to 4 were good in electrostatic leakage property even when the applied voltage was 60 KV. In the comparative example, leakage occurs at any applied voltage between 30 and 60 KV, and the electrostatic leakage property is better in the example.

Claims (2)

[Claims] 1. A solvent-based coating composition containing a powdery or flake-shaped conductive material, wherein the coating composition is 3 parts by weight per 100 parts by weight of the conductive material.
A metallic coating composition for electrostatic coating, comprising: 10 parts by weight of mechanically dispersed fine particulate organic amine-modified hectorite. 2. The electrostatic coating according to claim 1, wherein the organic amine-modified hectorite is added together with a part of the resin constituting the coating composition as a paste which is previously dispersed in the form of fine particles. Metallic paint composition for use.