JPS60120767A - Electrically conductive paint composition - Google Patents

Abstract

PURPOSE:To provide a paint compsn. which little causes precipitation of metallic powder during storage and gives a coating film exhibiting stable electrical conductivity over a long period of time, by incorporating two specified org. compds. in a principal component consisting of metallic powder and a thermoplastic acrylic resin. CONSTITUTION:The titled compsn. is obtd. by blending 0.5-3pts.wt. mixture consisting of 30-70wt% organosilicon compd. [e.g. gamma-(2-aminoethyl)aminopropyltrimethyoxysilane] and 70-30wt% organotitanium compd. (e.g. isopropyltriisostearoly titanate) with 100pts.wt. principal component consisting of 70-90wt% metallic powder (e.g. Ni, Al or Cu powder having a particle size of 2-50mu) and 30-10wt% thermoplastic acrylic resin (having an acid value of pref. 3 or below). The compsn. hardly causes precipitation of metallic powder during storage, is not solidified during storage, has excellent electrical conductivity, hardly causes lowering in electrical conductivity with time and gives a stable electrically conductive film having high reliability.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an electrically conductive coating composition in which precipitation of metal powder is reduced during storage and the coating film has stable electrical conductivity over a long period of time.

[Technical Background of the Invention and Problems Therewith] Recent electronic devices have become more efficient, lighter, thinner, and smaller due to dramatic advances in their components. Additionally, product assembly technology has been automated, resulting in high productivity. Against this background, conductive paints have become increasingly important and have had an indispensable position in production technology.

For this reason, the reliability of the conductive function is becoming more important.

However, it has been pointed out that many conductive paints tend to lose their conductivity in the environment after forming a coating film, and thus lack reliability in use. In other words, the conductivity of the formed coating film deteriorates due to external conditions such as dryness and high humidity. - The cause of this is not clear, but it is thought that continuous contact between metal powders caused by external conditions ('1) causes a combination of reduced contact and oxidation of the metal powder surface, resulting in poor conduction resistance. As a method to improve these, metal powder is plated with 〇 to prevent oxidation, and those used as an alloy are disclosed in Japanese Patent Application Laid-Open No. 53-135495 and Japanese Patent Application Laid-Open No. 56-365.
53 @, but all of them still have the drawback that the conductivity is not constant over a long period of time and the resistance changes.

Furthermore, since the paint is used after being diluted with an organic solvent, there is a drawback that the metal powder in the paint settles over time.

Furthermore, in extreme cases, the metal powder settles and solidifies during storage, which has the disadvantage that it requires a great deal of effort to redisperse it prior to use. No effective method has yet been found to overcome these drawbacks, and its development is awaited.

[Object of the Invention] The object of the present invention is to solve the above-mentioned C1
The object of the present invention is to provide a highly reliable electrically conductive coating composition that exhibits stable electrical conductivity over a long period of time, with less precipitation of metal powder during storage and less decrease in coating film conductivity.

[Summary of the Invention] As a result of intensive research to achieve the above object, it was discovered that the composition described below has less precipitation of metal powder and less decrease in conductivity.

That is, the present invention provides (a>metal powder, (b) thermoplastic acrylic resin, (C) organic silicone compound, and (d>
This is a conductive coating composition characterized by containing an organic titanium compound as a main component. More specifically, metal powder 70~
30 to 70 weight percent of an organic silicone compound and 70 to 3 weight percent of an organic titanium compound to 100 lfi parts of the main material consisting of 90 weight percent and 30 to 10 weight percent of a thermoplastic acrylic resin.
This is a conductive coating composition containing 0.5 to 311 parts of a mixture consisting of 0% serious injury.

Examples of the metal powder (a) used in the present invention include nickel, aluminum, copper, copper alloys, and metal powders whose surfaces are plated with silver, tin, etc. The average particle size of these metal powders is 2 to 50μ.
m is desirable.

(b) Thermoplastic acrylic resin used in the present invention is as follows:
Generally commercially available coating resins include polymers of acrylic esters and methacrylic esters, and copolymers thereof. The acid value of these resins is preferably 3 or less.

If the acid value exceeds 3, the organic silicone compound or organic titanium compound acts preferentially on the active hydrogen of acrylic acid, and the effect of the organic silicone compound or organic titanium compound is inhibited, so it is not 9f.

Further, in the present invention, the main material is composed of metal I) powder and thermoplastic acrylic resin. In that case, the blending ratio is 70% metal powder.
~90% by weight and thermoplastic acrylic resin 30-10% by weight
It is preferable that If the metal powder is less than 1% by weight, a practical level of conductivity cannot be obtained, and if it exceeds 90% by weight, no higher conductivity can be achieved and the adhesive force of the paint is undesirably reduced. Furthermore, if the thermoplastic acrylic resin is less than 10% by weight, the film-forming ability and adhesive strength will be lacking. If it exceeds 30% by weight, conductivity will be impaired, which is not preferable. Therefore, η is limited to the above range.

As the (0) organic silicone compound used in the present invention,
For example, γ-(2-aminoethyl)aminopropyltrimethoxysilane, γ-(2-aminoethyl)aminopropylmethyldimethoxysilane, N-β-(N-vinylbenzylaminoethyl)-γ-aminopropyltrimethoxysilane, etc. are listed as effective.

Examples of the organic titanium compound (d) used in the present invention include those having an alkoxy group and an alkyloxy group, such as isopropyl triisostearoyl titanate;
di-n-butoxy-bis(l-reethanolaminate)
Effective examples include titanium, isopropoxytri(N-aminoethylaminoethoxy)titanium, and the like.

In the present invention, a mixture of an organic silicone compound and an organic titanium compound is blended to a certain extent into the above-mentioned main material, and the mixture is blended as follows. That is, it is preferable that the organic silicone compound be 30 to 70% by weight and the organic titanium compound be 30 to 70% by weight. If H is less than 30% by weight, it is not effective and the long-term conductivity f1 decreases, which is not preferable. These organic silicone compounds and organic titanium compounds alone have no effect, but a mixture of the two exhibits a synergistic effect.

The mixture of the organic silicone compound and the organic titanium compound must be blended in an amount of 0.5 to 3 parts by weight based on 100 mm parts of the total main material. The amount of the mixture is 0.5fiffi
If it is less than 3 parts by weight, it is not effective in preventing sedimentation and maintaining conductivity, and if it exceeds 3 parts by weight, it is not preferable because it increases the cost and is not effective. By using organic silicone compounds and organic titanium compounds, there is little precipitation of metal powder, it does not solidify even after long-term storage, and exhibits excellent conductivity with no deterioration phenomenon observed in moisture resistance tests. Ta.

The reason for this is not clear, but it is thought that the organic silicone compound and the titanium compound react or coordinate with the polar groups of metal powders, resins, etc., making the paint stable and making it difficult for metal powders to settle. In particular, organic silicone compounds and organic titanium compounds strongly adsorb onto the metal surface and form a monomolecular layer or more, protecting the metal surface from oxidation and increasing compatibility with the thermoplastic acrylic resin. It is presumed that the stability of the paint is protected.

In order to prepare a paint using the conductive paint composition of the present invention, a stirring method, a ball mill method, a ball mill method, etc. using a solvent such as toluene,
Obtained by roll mill method.

These paints are applied to the housings of electronic devices by brushing, spraying, or screening methods.

[Embodiments of the Invention] Examples of the present invention will be described below. The present invention is not limited to this example.

Examples 1 to 4 Paints were obtained by dissolving a thermoplastic acrylic resin (acid value: 2), nickel powder (average particle size: 3 μm), an organic silicone compound, and an organic titanium compound in a solvent with the composition shown in Table 1. The resulting paint was added to a depth of 15 cm in a cylindrical glass container with a depth of 20 CIl11 and a diameter of 10 cm, and the downward settling property of metal was tested. It was also coated on an AB'S resin plate with a thickness of 31101, a length of 200 mm, and a width of 200 mm using a bar coater method to a thickness of 50 to 60 μm and dried at room temperature.
A coating film was formed by leaving it to stand for 4 hours, and the surface resistance of this film was tested under normal conditions and after 5 cycles, each cycle consisting of 2 hours at -30°C and 2 hours at 85°C. These results are shown in Table 1.

Comparative Examples 1-2 Paints were prepared in the same manner as in Examples 1-4 using the compositions shown in Table 1, and the settling properties and surface resistance were tested in the same manner. These results are shown in Table 1.

Examples 5 to 7 Thermoplastic acrylic resin (acid value 1) and average particle size 10f1
Paints were prepared in the same manner as in Examples 1 to 4 using the copper powder, an organic silicone compound, and an organic titanium compound according to the composition shown in Table 2, and the sedimentation properties and surface resistance of the paints were tested in the same manner. These results are shown in Table 2.

Comparative Examples 3-4 Paints were prepared in the same manner as in Examples 1-4 using the compositions shown in Table 2, and the settling properties and surface resistance were tested in the same manner. These results are shown in Table 2.

Table 1 *3 Indicates the extent to which it sinks in 1 hour.

Table 2 *2 Isopropoxy-1 to (N-aminoedylaminoethoxy) titanium As is clear from Tables 1 and 2, the composition of the present invention has excellent sedimentation properties and stability of surface resistance. It can be seen that

[Effects of the Invention] The conductive coating composition of the present invention exhibits excellent electrical conductivity, with little sedimentation of metal powder during storage, and no solidification, and a conductive film that is stable against changes over time. , and a highly reliable conductive coating film can be obtained.

Claims (1)

[Claims] 1. A conductive coating composition characterized by containing as main components (a) metal powder, (b) thermoplastic acrylic resin, (C) organic silicone compound, and (d) organic titanium compound. . 2. For 100 parts by weight of the main material consisting of 70 to 90% by weight of metal powder and 30 to 10% by weight of thermoplastic acrylic resin,
The conductive coating composition according to claim 1, characterized in that 0.5 to 3 parts by weight of a mixture consisting of 30 to 70% by weight of an organic silicone compound and 70 to 30% by weight of an organic titanium compound is blended. 3. The conductive coating composition according to claim 1 or 2, wherein the thermoplastic acrylic resin has an acid value of 3 or less.