JPS60228576A - Electrically conductive paint - Google Patents

Abstract

PURPOSE:To provide an electrically conductive paint which contains an electrically conductive filler uniformly dispersed therein and can form an electrically conducive film which can not be peeled off by friction, by adding an electrically conductive filler having a surface treated with low-temperature plasma, to a synthetic resin vehicle. CONSTITUTION:An electrically conductive paint is obtd. by adding an electrically conductive filler (e.g. metal such as Cu, Ni, Al or Ag, or an oxide thereof, graphite powder, carbon black or fiber) having a surface treated with low-temperature plasma generated by exciting a gas such as O2, N2, Ar or He with glow discharge, to a vehicle obtd. by dispersing a synthetic resin (e.g. polyester resin) in water or an org. solvent, and kneading the mixture. Though the paint has a high filler content, it has excellent liquid stability and coatability and gives a coating film having excellent electrical conduction performance, surface durability, adhesion to substrates, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Field of Application> The present invention relates to a conductive coating material which has excellent liquid stability as a coating material and has improved durability of the coated film obtained.

<Conventional examples and their problems> Conventionally, carbon black, graphite, nickel,
Conductive paints dispersed in conductive filler resins such as copper and silver can be used as packaging materials for preventing electrostatic damage to protect resistors and electrode materials in electrical circuits, heating elements in planar heating elements, semiconductors that are sensitive to static electricity, etc. It is also used in a wide range of fields such as electromagnetic shielding, electromagnetic shielding, and radio wave reflection.

The conductivity that the conductive paint should have varies depending on the application, but in general, static electricity prevention uses require a specific resistance value of 106Ω-α or less, and electromagnetic shielding requires a specific resistance value of 10°Ω-α or less.
h''-1 is required to have high conductivity below α, and is made into a paint by combining various resins and conductive fillers.The main conductive mechanism is due to contact between particles, so if the concentration is low, conductive Filler comrades b' - They do not make sufficient contact and become isolated in the resin, making it impossible to obtain high conductivity.Although it depends on the type and shape of the conductive filler, it is currently unavoidable to add it at a high concentration. be.

Generally, if the concentration of conductive filler is high, the conductivity will increase, but on the contrary, the suitability as a paint will decrease.

In other words, it becomes difficult to uniformly disperse the paint, causing precipitation and separation of the conductive filler, and loss of coating suitability.Furthermore, the resulting coated film suffers from reduced adhesion to the substrate and deterioration of mechanical strength such as flexibility. Furthermore, based on these defects, the conductivity of the coating start area and the coating area after a certain length of coating is different, etc.
Are there any drawbacks such as not being able to obtain uniform conductivity, or the coating peeling off due to friction and reducing conductivity? had.

To solve this problem, alkylamine salts, alkylbenzene sulfonates, and
Alkyl phosphate ester salt, alkylamine hydrochloride,
Surfactants such as norpitan fatty acid ester, sodium oleate, fatty acid amide, etc.? However, if too little is added, sufficient effects will not be obtained; if too much is added, problems such as deterioration of adhesion to the base material and decrease in conductivity may occur. However, it is difficult to obtain a coating film with sufficient conductivity, to obtain a uniform conductive coating film, or to adhere to a substrate with sufficient adhesive strength so that it does not peel off due to friction or other physical processing. It is a contradictory requirement to be able to produce a coating film without any paint film, and this problem has not been satisfactorily solved to date.

<Purpose of the Invention> The present invention has been made to address the above-mentioned problems, namely, to provide a conductive material in which conductive filler is uniformly dispersed without relying on a dispersion aid such as a surfactant. The electrical conductivity of the resulting coating film is almost the same at the beginning of coating and thereafter, and the electrical conductivity that can be formed is such that it does not peel off due to physical treatment such as friction. The aim is to provide paints.

<Summary of the Invention> In other words, the present invention is a synthetic tree resin. Oxygen, nitrogen, argon, etc. into a vehicle dispersed in water or an organic solvent.
This is a conductive paint made by adding and kneading a conductive filler whose surface is treated with low-temperature plasma excited and generated by a glow discharge of a gas such as 1 um.

<Specific Description of the Invention> The synthetic # fingers in the present invention include ethylene-vinyl acetate copolymer, acrylic resin, alkyd resin, urethane steel resin,
Resins such as amine resins, vinyl chloride resins, salt-vinyl acetate resins, cellulose resins, butyral resins, and film-based resins?
These synthetic resins can be used alone or as a mixture, and are added and kneaded to a vehicle made by dispersing these synthetic resins in water or an organic solvent such as ethyl acetate, methyl ethyl ketone, toluene, or alcohol, and then adding a conductive filler whose surface has been treated with low-temperature plasma. The synthetic resin is selected depending on the application, such as the base material of the object to be coated, and is not particularly limited.

The conductive filler in the present invention is copper, brass, nickel,
It is made of metals such as aluminum, silver, gold, iron, and stainless steel, and their oxides, or powder or fibers of graphite and carbon black.

Low-temperature plasma is a highly ionized plasma gas generated by high-frequency discharge, glow discharge, etc. under reduced pressure, and is a low-temperature plasma that is a system in which electron temperature and molecular mastery (gas temperature) are separated. .

Surface treatment by low temperature plasma in the present invention is 0.0
Under a reduced pressure of about 1 Torr to 10 Torr, use of one or a mixture of two or more inert gases such as oxygen, nitrogen, hydrogen, carbon dioxide, ozone, or argon, helium, or neon as the gas, and start the discharge without starting the discharge. Direct current, commercial waves, high frequencies, microwaves, etc. are used as the frequency of the high voltage to be sustained.

Generates low-temperature plasma. Further, there are two types of discharge electrodes: an external electrode type and an internal electrode type, but these are not particularly limited in the present invention. The low-temperature plasma irradiation conditions are such that electric power, pressure inside the vacuum container, gas flow rate, irradiation time, etc. are changed depending on the conductive filler and type of gas used.

The effects of the low-temperature plasma treatment in the present invention are thought to be due to the surface cleaning effect and etching effect by removing foreign substances, impurities, oily films, etc. adhering to the surface of the conductive filler. Compatibility with synthetic resins and dispersibility into vehicles without deteriorating the performance of conductive fillers.
This is a significant improvement.

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

[Example 1] Carbon black (pre-coupler (manufactured by Denki Kagaku Kogyo)) was added to the sample boat (8) of the plasma processing apparatus shown in Fig. 1.
? Place argon gas into the vacuum container (1) from the gas introduction tube, adjust the gas pressure to <0.5 Torr, and set the discharge power Q to the high frequency power source (6) with a frequency of 13.54 MHz.
Under the condition of 200 W, the processing time was varied (■3
Surface treatment was performed for 0 sec, 6.0 sec, and 180 sec.

Next, this processed carbon black ■■■? A paint was created using the following recipe.

Paint plasma-treated carbon black 100 parts by weight Po1
1 Ester resin (Vylon #200 manufactured by Toyobo ■) 30
0 #Toluene 500 // Methyl ethyl ketone 500 // In addition, the paint using carbon black is called ■,
Q) What paint did you use?

The obtained conductive paint ■■■ 75 lines, 135μ engraving gravure plate with polyester film (25μ thickness) ~ 30
What is the performance of the conductive film obtained by gravure coating with a width of 0 m/m for 1.000 m? The evaluation was shown in (Table 1).

[Comparative Example 1] Using untreated carbon black, it was made into a paint and gravure coated in the same manner as in the example.

Measuring method> *1 Surface resistance: The resistance value was measured at intervals of 10 m/rn by sampling the coating start area and the 1000 m processed area.

*2 Abrasion resistance: Friction tester compliant with JIS-L-o-a 23 ■Use on a wall and fix it so that friction is applied between the coated surfaces.

The resistance was measured after 200 reciprocating movements. (In addition, the first evaluation sample was measured at the beginning of coating.) As shown in Table 1, the conductive paint obtained had higher conductivity than the untreated product (Comparative Example 1). The untreated product showed a decrease in conductivity as the coating progressed. This is because the conductive paint using plasma-treated carbon black has a good and uniform dispersion state, so the performance changes.
This is thought to be due to the fact that the dispersion state of the paint is unstable, and agglomeration and separation have progressed, resulting in changes in the composition of the resulting paint.

Compared to the untreated product (Comparative Example 1), this product has excellent abrasion resistance with less carbon blank falling off due to better compatibility at the interface between the synthetic resin and carbon black.

[Example 2] Nickel powder (carbonyl nickel-287 (Fukuda Metals)
(manufactured by)) Using the same equipment as in Example 1, using hydrogen gas TTV, 1.0 Torr, 200 W, processing time 60 seconds.
Surface treatment under the conditions of c? Using the resulting plasma treatment and nickel powder as a conductive filler, a paint was prepared using the following formulation.

The resulting 4-acid paint was made into an ABS resin plate with a thickness of 2 m/m.
゛Spray coated conductive resin layer? formed.

[Comparative Example 2] Untreated nickel powder was made into a paint and spray coated in the same manner as in Example 2.

The relationship between the thickness and acid-conducting surface resistance of the conductive resin 1- according to Example 2 and Comparative Example 2 is shown in FIG.

In FIG. 2, Example 2 is indicated by the symbol A, and Comparative Example 2 is indicated by the symbol B.

As is clear from the results shown in Fig. 2, the paint made of nickel powder treated by the method of the present invention is significantly lower than that made with untreated product 1 even if the paint is obtained by the same composition and processing method. Because the dispersion is uniform, there is good contact between particles,
A conductive paint with high conductivity can be obtained.

<Effects of the Invention> As described above, the conductive paint obtained by the present invention has excellent liquid stability and coating suitability even in a composition with a high conductive filler content, and the resulting coating film is uniform and reproducible. It has characteristics such as excellent electrical conductivity, P, L, surface resistance, and mechanical strength such as adhesion to substrates.

[Brief explanation of the drawing]

The drawing shows an embodiment of the present invention (Fig. 1).Is it a mixing mechanism in which the sample board rotates half a rotation repeatedly? An explanatory diagram of the built-in high-frequency discharge plasma device for powder processing, Figure 2 shows plasma treated (Example 2) and non-plasma treated (Comparative Example 2)
A graph showing the relationship between film thickness and surface resistance of paint using nickel powder. (1)...Vacuum vessel (2)...Electrode (3)...Exhaust pipe (4)...Gas introduction pipe (5)...Matching circuit (
6)...High frequency power supply (7)...0 ring (8)...
Sample board (9)...Sample patent applicant Kazuo Suzuki, representative of Toppan Printing Method Company

Claims (2)

[Claims] (1) Synthesis #Surface treatment with low-temperature plasma generated by exciting a gaseous glow discharge such as oxygen, nitrogen, hydrogen, argon, helium, etc. into a vehicle dispersed in greasy water or an organic solvent. A conductive paint made by adding and kneading a conductive filler. (2) The conductive paint according to claim 11, in which the conductive filler is made of metals such as copper, brass, nickel, aluminum, and silver, and their oxides, or graphite, carbon black powder, or fibers. .