JPS58194962A - Water-resistant, electrically conductive paint - Google Patents

Abstract

PURPOSE:To provide a water-resistant, electrically conductive paint which has resistance to temperature changes and can form a coating film capable of withstanding temperature change or dew condensation, by using an emulsified resin of an alkylene (co)polymer and colloidal silica in combination. CONSTITUTION:A water-resistant, electrically conductive paint consists of an aq. compsn. contg. 10-60wt% raw compsn. consisting of 10-90wt% electrically conductive pigment such as graphite or carbon black, 2-40wt% emulsified resin of an alkylene (co)polymer such as aq. emulsion of vinyl acetate resin or acrylate ester resin, 0.5-20wt% colloidal silica and 0.2-8wt% dispersant or suspending agent such as sodium naphthalenesulfonate or carboxymethyl cellulose. This paint has resistance to change in temperature and moisture and can form an electrically conductive film having good water resistance and adhesion.

Description

[Detailed description of the invention] The present invention relates to a water-resistant conductive paint.

Furthermore, the present invention relates to a coating composition that forms a conductive coating film that is resistant to changes in temperature and humidity, and has good water resistance and adhesion. .

Conventionally, conductive paints of various compositions have been used for printed wiring, surface heating elements, and antistatic purposes. In other words, conventional conductive paints include conductive paints made of graphite, carbon black, metal powder, metal compounds, etc., alkylene polymers and copolymers, phenolic resins, acrylic resins, methyl ethyl cellulose, drying oils, etc. It consists of a dispersant, a dispersant, a solvent, etc.

The conventional conductive coating compositions described above contain a fairly large amount of binder to prevent peeling of the applied film. However, if the content of the binder is high, not only will the electrical resistance of the coating film become high, but the coating film will also be more susceptible to temperature changes and the effects of Fr1ll. The problem was that the paint film would peel off if it was repeatedly damaged by thermoelectric changes up to high temperatures, such as the heat generated by water, or by moisture changes from a dry state to a frozen state with condensation.

For example, conductive paint is used on the inner and outer surfaces of cathode ray tubes, but while cathode ray tubes are sometimes exposed to cold temperatures during transportation, when cathode ray tubes are used, they become hot due to the heat generated by the plow/tube themselves, and they also become unstable. During use, the temperature changes repeatedly, resulting in lower temperatures. Furthermore, the moisture content varies depending on the environment in which it is used. Therefore, the conductive paint for the outer surface of the cathode ray tube can be used at these temperatures, lI! Performance that can sufficiently withstand changes in ll& is required, but conventional paints have not been satisfactory.

Therefore, the present invention eliminates these drawbacks in the prior art. This is the purpose. That is, the present invention has resistance to temperature changes and Ivi! change in degree,
A new water-resistant, electrically conductive paint that forms a coating that can withstand water damage.1. 1□ ′:;□・ From this point of view, the present inventor has conducted various researches, and as a result,
i'e kotoden ratio change resistance? We have discovered a new water-resistant conductive coating composition that forms a coating film that has a 1 to 1 to In paints, adhesive strength and water resistance can be improved by using a binder together with an emulsified resin of an alkylene polymer or copolymer such as vinyl acetate or acrylic ester, and colloidal silicic anhydride. It is possible to greatly improve the tv of the binder itself and to reduce it compared to conventional ones.In addition, by reducing the amount of binder, the electrical resistance value is lower than conventional ones, improving the function as a conductive paint. It is something that can be done.

That is, the water-resistant conductive paint of the present invention contains a conductive pigment.
Raw material components consisting of 10-90% emulsified resin of alkylene polymer or copolymer 2-40% colloidal silica 0.5-20% dispersing agent and suspending agent 0.2-8% 1
Aqueous containing 0-60%.

It is a composition. In this specification, % refers to % by weight.

Here, the conductive material refers to graphite, carbon black, a mixture thereof, and various other powder N materials having conductive materials. If the content of the conductive material in the raw material composition is less than 10%, it is not suitable because the conductivity of the coating film decreases. Furthermore, if the content of the conductive pigment exceeds 90%, the amount of the binder, dispersant, etc. will decrease, making it impossible to form a very tough coating film, which is inappropriate.

The emulsified resin of the alkylene polymer or copolymer refers to an aqueous emulsion of vinyl acetate resin, acrylic ester resin, ethylene/vinyl acetate copolymer, etc., and accounts for 2 to 40% of the raw material composition. @1 emulsifying resin is 2%
If the amount is less, good coating film formation will not be achieved and the coating film will become brittle. On the other hand, if it exceeds 40%, the paint film will change fP due to greenhouse or humidity changes.

This is not preferable because the resistance of KN↑ is lost and the conductivity is also lowered.

The colloidal silicic anhydride is a component of the water-resistant conductive paint of the present invention, and by adding it, it can be added to the emulsified resin binder with low Ptc.
It can be used for a long time, and it can be made water resistant. The addition JII is 0.5 to 2 for the raw material #I composition.
A range of 0% is preferable; if it is less than this range, the effect of adding colloidal silicic anhydride will hardly be observed, and if it exceeds the above range, the elasticity of the coating will decrease, and m<
Further, it is not preferable because the conductivity tends to decrease.

The dispersing agent and suspending agent are used to uniformly disperse the conductive pigment in the paint, and appropriate agents such as naphthalene sulfone soda and carboxymethyl cellulose can be used. The appropriate amount of addition is within the range of 12 to 8% in the raw material composition; if it is less than this, the dispersion effect will not be sufficient, and if it is too large, it will deteriorate the properties of the coating film, so it is not preferable. .

The water-resistant conductive coating material of the present invention can be adjusted in temperature by appropriately selecting the above-mentioned raw materials, weighing them, and mixing them in a known manner.

The invention below? This will be explained in more detail with reference to Examples.

Ingredients shown in Example 1 below? Each paint obtained by mixing,
Various test specimens were prepared by coating onto a 80B x 150i F11 x 8 glass plate so that the dry M thickness was 10μ, 30μ and 60μ.

(a) Electrical resistance The relationship between film thickness and electrical resistance was measured for the soil and mud test pieces. Measurement was performed using a Wheatstone bridge with lil+2 between the electrodes.
Measured as 10 steel. The results are shown in FIG.

(b) Durability (1) Each test piece with a film thickness of 60μ? After being immersed in boiling water for 20 minutes, the condition of the coating film was observed.

(c) Durability (...) Each test piece with a film thickness of 30μ) was kept at -20°C for 120 minutes, then left at 25°C and 60% RH for 15 minutes.
1 cycle and 2 cycles of temperature change were applied◎
□′・ The test results for (b) and (c) above are shown in Table 2 below.

Table 1 Coating composition Table 2 Water resistance test results As can be seen from the results shown in Figure 1, the electrical resistance value of the coating film formed using the coating composition of the present invention was lower than that of Comparative Example C (conventional coating). low. Furthermore, as can be seen from the results shown in Table 2, the coating film formed using the coating composition of the present invention was
Compared to the comparative example, the water resistance (durability I) and the resistance to IM change (durability U) are excellent.

[Brief explanation of drawings]

Figure 1 shows the relationship between coating film thickness and electrical resistance in Examples. This is a graph showing. Agent: Kunihiko Masubuchi Figure 1: Atsushi (P)

Claims (1)

[Claims] 110 to 90% by weight conductive pigment - 2 to 40% by weight
Emulsifying resin of alkylene polymer or copolymer, 0.
'5 to 20% by weight of colloidal silicic anhydride, and 0.
A raw material composition comprising 2 to 8% by weight of a dispersing agent or suspending agent, and a water-resistant conductive paint comprising an aqueous composition containing 10 to 60% by weight. 2. The water-resistant conductive paint according to claim 1, wherein the conductive pigment is graphite or a mixture of graphite and carbon black. 3 Claims *1, wherein the alkylene polymer or copolymer is at least one substance selected from the group of vinyl acetate resins, acrylic ester resins, and ethylene-vinyl acetate copolymers. The second item is water-resistant conductive paint for grain distribution.