JPH02120373A - Conductive coating composition - Google Patents

Abstract

PURPOSE:To make it possible to form a coating composition useful as a primer which, when applied to the surface of an insulator such as a plastic, can make it electrostatically coatable with a top coating material by mixing a resin binder with a coated conductive filler obtained by coating a conductive filler with a conductive polymer. CONSTITUTION:This conductive coating composition comprises a coated conductive filler obtained by coating a conductive filler with a conductive polymer and a resin binder. Examples of the conductive filler include simple metals, metal composites, metal oxide semiconductors, metal oxide semiconductor composites, and conductive carbon and graphite. Example of the conductive polymer include poly-substituted acetylenes, polythiophene derivatives, and polypyrrole derivatives. As the resin binder, any one usually used as a coating resin can be used without any particular limitation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to conductive coating compositions. In particular, the present invention relates to a coating composition useful as a conductive brimer that enables electrostatic coating of a top coat by applying it to the surface of an insulating material such as a plastic.

When electrostatically painting insulating materials such as glass, a conductive brusher is often applied in advance in order to paint effectively and beautifully. The purpose is to quickly dissipate the electric charge on the surface of the object to be coated and to maintain the potential of the object to be 0 with respect to charged flying particles. The leakage resistance of such a conductive brimer is determined by the electrostatic coating efficiency and l! 1. From the viewpoint of safety against electric sparks, it is desirable that the resistance be less than 10''Ω, preferably less than 10'Ω.

[Prior Art] Conventionally, such conductive brushers have been applied to paint compositions containing appropriate amounts of a vine resin binder, additives, solvents, and conductive fillers adapted to the object to be coated so as to achieve a predetermined conductivity. has been done.

[Problems to be Solved by the Invention] However, in the coating films obtained from these conventional conductive coating compositions, electrical conduction paths are formed by contact between the electrically conductive fillers dispersed in the coating film, and electrical conductivity is not achieved. Because of this mechanism, when deformation forces such as expansion force and tensile force due to swelling act on the coating film, contact between the conductive fillers cannot be maintained, resulting in a decrease in conductivity. 0 For example, it is known that the solvent of the top coat applied during electrostatic painting of the top coat onto the conductive primer film causes the primer to swell and the conductivity to drop significantly.

Means for Solving Problem E] The present inventors have focused on these problems and have developed a method that ensures conductivity even when an external force is applied to the conductive coating film or when electrostatic topcoating is applied, and As a result of extensive research to reduce the amount of expensive conductive filler used, we have found that by using a conductive filler coated with a conductive polymer, we have found that it is resistant to deformation such as bowing force and swelling caused by solvents. The present invention was completed based on the discovery that it exhibits stable conductivity even when exposed to heat.

That is, the present invention relates to a conductive coating composition containing a coated conductive filler obtained by coating a conductive filler with a conductive polymer and a resin binder.

The conductive coating composition of the present invention will be specifically explained below.
The conductive filler in the present invention is either conductive itself or powder coated with a conductive substance, such as a single metal (silver, nickel, copper, etc.) or a metal composite plated with nickel. mica, nickel-plated phenolic resin powder, etc.), metal oxide semiconductor single bodies (zinc oxide doped with aluminum oxide, tin oxide doped with antimony oxide, etc.), metal oxide semiconductor composites (oxide semiconductor coated with semiconductor tin oxide, etc.) Examples include titanium, mica, whiskers, etc.), conductive carbon, and graphite.

The conductive filler may be spherical, flaky, or whisker-shaped, and may be used singly or in combination of two or more.

The coated conductive filler of the present invention is obtained by coating the above conductive filler with a conductive polymer. As a conductive polymer, its own volume resistivity is 10'Ω・
cm or less, preferably 10'Ωcm or less, and is liquid itself or can be dissolved in a solvent to become liquid. For example, Hyboron CTN-131 (solid content 60% by weight, manufactured by Boron International) charge transfer type conjugate boron polymer R, -CE (liquid), high boron CTP-200 (liquid with solid content of 60% by weight), -CE (where = integer from 1 to 6, ff = 1 to 6) is an integer.

) polysubstituted acetylenes such as (C:
HzLnH, (CHt)qsOsNa, -CH20+
cH, hOMe.

-CH20(CH2) 20clIJMe, -CH2
A group represented by NHC (CH2hle etc., where n
and q both represent integers of 4 to 12, etc.; (wherein, γ represents an integer of 50 to 500, and R1 represents -C
Examples include polypyrrole derivatives such as a group represented by CH, ), H, etc., where X is an integer of I9 to 19.

In the present invention, the surface of the conductive filler needs to be partially or entirely covered with the conductive polymer. The coating method includes dispersing the conductive filler in a conductive polymer liquid prepared by mixing a conductive polymer with a solvent and a dispersing resin as required, using a dispersion method commonly used in the paint field, such as a ball mill, sand mill, roll mill, etc. Examples of methods include dispersion using attritors, dispers, etc. This dispersion causes the conductive polymer to be adsorbed onto the surface of the conductive filler. The viscosity of the dispersion paste at the time of dispersion is preferably within the range of 30 to 200 KU from the viewpoint of dispersion efficiency.
After dispersing the conductive filler, a conductive polymer is blended to form a coating, but the effect is not sufficient.

The amount of the conductive polymer to be blended is preferably determined depending on the surface area of the conductive filler to be coated.

The amount of conductive filler per unit surface area (m2) is O
, l = l OOmg/m”, preferably 0.5-5
It is appropriate that the amount is in the range of 0 mg/m". If the amount of the conductive polymer is less than 0.1 mg/+n", the conductive filler will not be sufficiently coated, and the resulting conductive coating film will have a tensile strength. Due to deformation due to force or expansion force, the conductivity decreases significantly (the effect of the present invention becomes smaller.On the other hand,
mg/m" (if the amount exceeds the amount required for adsorption to the entire surface of the conductive filler, there will be little effect of further improving the conductivity (and if the excess conductive polymer is present in the matrix of the resin binder) However, poor compatibility with the base resin tends to cause poor appearance of the coated surface and deterioration of the physical properties of the coated film.

The composition of the present invention contains the above-mentioned coated conductive filler and resin binder as essential components.

The resin binder in the present invention is usually
Those used as resins can be used, and are not particularly limited (for example, acrylic resins, polyester resins, polyurethane resins, vinyl chloride resins, chlorinated polyolefin resins, polybutadiene resins, Evoquin resins, etc.) can be used. These resins may be of a thermoplastic type (lacquer curing type) or may be a crosslinked curing type used in combination with a crosslinking agent such as polyisocyanate or melamine resin.The above resins may be used alone or in combination of two or more types. You may.

The effect of imparting stable conductivity in the present invention is remarkable when the resin binder is a thermoplastic type (lacquer hardening type).

When the composition of the present invention is used as a brimer for plastics, the resin binder may be an acrylic resin, a polyurethane resin, or a chlorinated polyester resin. Resistance value is 10'Ω・cm, preferably io
It is appropriate to mix it so that it is less than 'Ω・cm,
The coated conductive filler (converted to the amount of conductive filler before coating) is suitably blended in an amount of 5 to 200 parts by weight, preferably 10 to 150 parts by weight, based on 100 parts by weight of the resin binder.

The coating composition of the present invention may contain various known substances such as pigments, solvents, plasticizers, dispersants, coating surface conditioners, fluidity conditioners, ultraviolet absorbers, ultraviolet stabilizers, and antioxidants, as desired. It can be used as

Furthermore, the coating composition of the present invention can be coated by conventional coating methods. In other words, the paint is diluted with a solvent to the appropriate viscosity for painting, if necessary, and then sprayed with an air spray machine.
It can be applied at room temperature or with heating using an airless sprayer, dipping, roll coating machine, coating, etc.

After coating, the coating composition of the present invention is dried by heating or at room temperature. Conditions for heating may be appropriately selected depending on the type of resin binder used and the fffi of the object to be coated, but usually 40-160" C1, preferably 70-14
It may be heated at 0''C for about 5 to 40 minutes.

[Action of the Invention] The reason why the conductive coating film obtained from the composition of the present invention maintains good electrical conductivity even when it is deformed is that even if the coating film is deformed and the contact points between the conductive fillers are separated, the filler remains intact. This is thought to be because the covering conductive polymers are intertwined with each other and a conductive path is secured through the conductive polymers.

Incidentally, if the conductive polymer is added in a step after dispersion, the effects of the present invention cannot be obtained.

[Effects of the Invention] As explained above, according to the present invention, since the surface of the conductive filler is coated with a conductive polymer, the conductive coating film obtained has good conductivity even when deformed. For example, even when an electrostatic top coat is applied to a conductive brimer obtained by using the composition of the present invention as a brimer, there is little decrease in conductivity, the top coat has good coating efficiency, and a good finish is obtained. A coating film is obtained.

The present invention will be further explained below with reference to Examples.

Example 1 Conductive powder W-1 (manufactured by Mitsubishi Metals Corporation, titanium oxide pigment coated with tin oxide) 120 g, high boron CTN-
A mixture of 16.7 g of No. 131 (manufactured by Boron International, 60% conductive polymer solution), 50 g of toluene and 50 g of isopropanol was dispersed in a sand mill until the particle size as measured by a tube gauge became 5 gm.
7g of millbase was obtained.

Super Chron 822 (manufactured by Yamaba Kokusaku Valve Co., Ltd., 20% chlorinated polypropylene solution) 450 was added to the obtained mill base.
gO[/BYK-300 (manufactured by Big Chemie Japan Co., Ltd.,
686.8g with the addition of 0.1g of silicone surface conditioner)
A coating composition was obtained. Next, this paint composition was diluted with toluene to a viscosity of 12 seconds () Ord Cup No. 4/20.
'C) and air sprayed this product onto a polypropylene automobile bumper (cut into 15 x 7 cm) to give a dry film thickness of 17 gm. 30 at 80'C
After drying for a minute, the resistance value was measured between points separated by 14 cm on the brusher coated surface using a 3110 battery-type insulation resistance tester (manufactured by Nichicho Denki ■).

In addition, the brimer coated plate obtained above and the cold-rolled steel plate were lined up, and at the same time, both were coated with Rafflex No.
. 1200 White (manufactured by Kansai Paint Co., Ltd., L wave type solid color topcoat) was applied uniformly to both cold rolled steel plates so that the dry film thickness was 20 gm. After the completion of the coating, the resistance value was measured between points 14 cm apart on the top-coated brusher surface at 8 and 60 seconds after 10 seconds had elapsed.

Then, 2 minutes after finishing painting, Sofre Nx No.

1200 White was further coated in the same manner so that the overall thickness of the top coat on the cold rolled steel plate was 35 gm, and the coating was uniformly applied to both, and then baked at 120°C for 30 minutes.

The topcoat coating efficiency was calculated and the appearance of the finished coating was evaluated for the obtained topcoat coated plate on the brimer plate. The results are shown in Table-1.

Example 2 A mixture of 120 g of conductive powder W-1, 4 g of 50% poly-3-octylthiophene (a toluene solution of a conductive polymer with a peak molecular weight of 20,000 by gel permeation chromatography), and 150 g of toluene was mixed in a disper for 30 minutes. After stirring for a minute, 100 g of Super Chron 822 was added to the mixture and dispersed in a sand mill until the particle size measured by a tube gauge became 5 gm, yielding 374 g of millbase.

Add 400g of Sulperclone 822 to this mill base and 0.1g of BYK-300 to Sara, mix, and mix 774
．． 1 g of coating composition was obtained.

This product was painted and evaluated in the same manner as in Example 1. The results are shown in Table-1.

Example 3 To 236.7 g of a mill base made in the same manner as in Example 1, 300 g of Sunblen PU-805 (manufactured by Sanyo Kasei Co., Ltd., 30% polyurethane elastomer) was added, and further BYK-3 was added.
00 was mixed with 1 g of O, stirred, and 536. A coating composition of sg was obtained.

This coating composition was diluted in the same manner as in Example 1, and the same procedure as in Example 1 was conducted except that a noryl resin for automobile exterior panels (cut into 15×7 cm) was used as the object to be coated. Display the results -
Shown in 1.

Example 4 Conductive mica 33F-110C (manufactured by Sanyo Shiki Co., Ltd.) 50 g
, 3.3 g of Hiboron CTP-200 (manufactured by Boron International, 60% conductive polymer solution) and 60 g of toluene were mixed and stirred with a disper for 30 minutes. Furthermore, 40 g of Super Chron 822 was added to this mixture and dispersed in a sand mill until the particle size as measured by a tube gauge became 20 gm to obtain 153.3 g of mill base.

Add 450 g of Super Chron 822 and 0.1 g of BYK-300 to this mill base and stir.
．． 4 g of coating composition was obtained.

Then, dilution, coating, and evaluation were performed in the same manner as in Example 1. The results are shown in Table-1.

Comparative Example 1 120 g of conductive powder W-1, 50 g of Super Chron 822, 25 g of toluene and 25 g of isopropanol
Disperse the mixture with a sand mill until the particle size becomes 5 pm,
220 g of millbase was obtained.

Thereafter, 670.1 g of a coating composition was obtained in the same manner as in Example 1. In addition, this coating composition was diluted in the same manner as in Example 1.
Painted and evaluated. The results are shown in Table-1.

Comparative Example 2 120 g of conductive powder W-1, 50 g of Super Chron 822, 25 g of toluene and 25 g of isopropanol
Disperse the mixture with a sand mill until the particle size becomes 5 pm.
20g of millbase was obtained.

Add 16.7 liters of Hiboron CTN-131 to this mill base.
g, 400g of Super Chron 822 BYK-300
0.1 g was added to obtain 636.8 g of a coating composition.

Then, dilution, coating, and evaluation were performed in the same manner as in Example 1. The results are shown in Table-1.

Comparative Example 3 120g of conductive powder W-1, Sunblen PU-805
, 50 g of 'r-luene, and 50 g of isopropanol were mixed, stirred with a disper for 30 minutes, and then dispersed with a sand mill to a particle size of 5 μm to obtain 253.3 g of millbase.

Add 300 g of Sunbren PU-805 and 0.1 g of BYK-300 to the mill base and stir to obtain 553.4 g.
A coating composition of g was obtained.

Then, coating and evaluation were performed in the same manner as in Example 3. The results are shown in Table-1.

Comparative Example 4 50 g of conductive mica 53F-110c, 50 g of Super Chron 822, and 50 g of toluene were mixed, stirred for 30 minutes with a disper, and then dispersed with a sand mill until the particle size measured by a tube gauge was 20 pm to obtain 150 g of a mill base.

Add 450 g of Super Chron 822 to the mill base, BY
0.1 g of K-300 was added to obtain 600.1 g of a coating composition.

Then, dilution, coating, and evaluation were performed in the same manner as in Example 1. The results are shown in Table-1.

Claims (1)

[Claims] 1. A conductive coating composition containing a coated conductive filler obtained by coating a conductive filler with a conductive polymer and a resin binder.