JPH08283517A - Conductive resin composition - Google Patents

Abstract

PURPOSE: To obtain a conductive resin composition free from any organic solvent so as to be nondeleterious to the working environment and capable of being thickly applied. CONSTITUTION: This composition is prepared by kneading 100 pts.wt. gold powder, silver powder or silver-plated copper powder, 12-20 pts.wt. binder comprising a mixture containing an acrylic emulsion and an epoxy emulsion each of which is prepared by using a polyester material as emulsifier in a mixing ratio of (85-50)/(15-50) (the ratio in terms of solid content), and 0.1-2wt.% dispersant comprising a water-soluble sodium or potassium salt of a saturated fatty acid (e.g. lauric or myristic acid) or of an unsaturated fatty acid (e.g. oleic or linolic acid).

Description

Detailed Description of the Invention

[0001]

This invention relates to a water-soluble conductive resin composition.

[0002]

[Technical background] Conventionally, as a material which obtains conductivity by being dried at room temperature, a conductive paint or a conductive adhesive using a metal powder such as silver or copper and an acrylic resin capable of drying at room temperature as a binder has been commercially available. ing. However, these conductive paints or conductive adhesives use an organic solvent in order to dissolve the acrylic resin or the like as a binder,
Due to the effects of organic solvents on the human body, it was necessary to pay sufficient attention to the work environment.

As a means for solving the influence of the organic solvent on the human body, the inventors of the present invention have disclosed "Japanese Patent Application No. 5-275664".
As shown in, a conductive composition using an acrylic emulsion of acrylic resin and water as a binder was proposed.

[0004]

However, as a result of subsequent studies, it has been found that this composition has a drawback that cracks easily occur after drying when the coating film becomes thick.

Under the above circumstances, the present invention uses a binder in which the solvent is water, is friendly to the working environment, and does not cause cracks even when the coating film becomes thick during coating, and the conductivity is stable. An object is to provide a resin composition.

[0006]

In order to solve the above problems, the present invention relates to 100 parts by weight of metal powder, acrylic emulsion and epoxy emulsion using a polyester-based material as an emulsifier as a binder, and a total solid content. Then, 12 parts by weight or more and 20 parts by weight or less, and 0.1 parts by weight or more and 2 parts by weight or less of a water-soluble saturated fatty acid or unsaturated fatty acid metal salt as a dispersant are kneaded.

Here, as the metal powder, gold powder, silver powder, silver-plated copper powder and the like can be used. Also,
These shapes may be any shape such as flakes, resin, spheres, and irregular shapes, and the particle size thereof is preferably 100 μm or less, particularly preferably 1 to 30 μm.

The above-mentioned emulsion is a conventionally-known emulsion of resin and water (Q / W). When the solid content is less than 12 parts by weight, the binding of metal powder is poor and the resistance is high. At the same time, the adhesiveness also decreases.
On the other hand, if it exceeds 20 parts by weight, the amount of metal powder for imparting conductivity becomes insufficient and the resistance becomes high.

The acrylic emulsion preferably uses a polyester type emulsifier, and a concrete emulsifier is polyester polyol. Anionic emulsifiers commonly used in acrylic emulsions cause the metal powder to settle quickly, form a hard cake after the metal powder settles, and it is difficult to redisperse the metal powder during use, making it unusable. Also, acrylic emulsions that use anionic emulsifiers are neutralized with amine-based materials in the emulsion neutralization process, so when used in combination with silver-plated copper powder,
Copper of silver-plated copper powder is dissolved by the residue of the amine material,
Copper is ionized, which is not preferable.

As the epoxy emulsion, bisphenol A type emulsion, modified bisphenol A type emulsion and the like can be used.

The mixing ratio of the acrylic emulsion and the epoxy emulsion is preferably 85% by weight to 50% by weight of the acrylic emulsion and 15% by weight to 50% by weight of the epoxy emulsion based on the solid content of each emulsion.
If the mixing ratio of the acrylic emulsion exceeds 85% by weight, cracks are likely to occur in the coating film after drying, and if the mixing ratio of the acrylic emulsion is less than 50% by weight, drying of the coating film tends to be slow. The coating film is so soft that it cannot easily withstand physical impact.

If the amount of the metal salt of the saturated fatty acid or unsaturated fatty acid is less than 0.1 part by weight, the dispersion of the metal powder will be insufficient and the resistance will increase. Further, even if added in excess of 2 parts by weight, the effect of improving the conductivity cannot be obtained, and the adhesiveness with the adherend decreases.

Within the scope of the present invention, a sufficient effect of preventing the settling of metal powder can be obtained and a good conductive resin composition can be obtained, but a plate-like or rod-like powder for the purpose of preventing the settling of metal powder, For example, if talc, whisker of potassium titanate or the like is added, the effect is further improved.

The saturated fatty acid metal salt is a sodium or potassium salt of lauric acid, myristic acid or the like, which is soluble in cold water. Examples of the metal salt of unsaturated fatty acid include sodium or potassium salts of oleic acid and linoleic acid. The use of these dispersants is preferable because it promotes fine dispersion of the metal powder in the acrylic emulsion and forms a coating film having good conductivity.

[0015]

EXAMPLES Examples 1 to 1 with the composition (% by weight) shown in Table 1
6, Comparative Examples 1 to 3 and Conventional Examples 1 to 3 were manufactured, and various tests were conducted on them, and the results are shown in the lower column of Table 1.
Details of kneading the composition and various tests are as follows.

[0016]

[Table 1]

[0017]

[Kneading of composition] After weighing each composition into an appropriate container,
The resin composition was stirred for 10 minutes with a stirrer.

[0018]

[Method of measuring specific resistance (conductivity)] A glass epoxy substrate was coated with the resin composition in a width of 2 mm and a length of 60 mm using a doctor blade, and then left to dry at room temperature for 10 minutes.
The resistance value and the thickness of the resin composition having a length of 60 mm after drying were measured to determine the specific resistance.

[0019]

〔Evaluation criteria〕

 ◯: The coating film does not peel off. X: The coating film is easily peeled off.

[0020]

〔Evaluation criteria〕

◯: The metal powder does not settle even after 24 hours have passed, and after standing for 1 week, the precipitated metal powder can be easily re-stirred. X: All the metal powder settles within 1 hour, and it is difficult to disperse the metal powder by stirring again.

[0021]

〔Evaluation criteria〕

 ◯: No crack was generated even after 24 hours. X: A crack occurs within 24 hours.

[0022]

〔Evaluation criteria〕

 Good: No blue precipitate is generated even after one week. X: A blue precipitate is generated in less than 3 hours.

[0023]

〔Evaluation criteria〕

 ◯: No sticking to fingers after 1 hour. X: Sticks on the finger even after drying for 24 hours.

From the above test results, it can be understood that each of the examples can sufficiently be used as the conductive resin composition. On the other hand, in Comparative Example 1, since the emulsion is less than 12 parts by weight, the adhesion is poor, and since the ratio of the epoxy emulsion is less than 15% by weight, cracks occur after drying. In Comparative Example 2, the amount of emulsion exceeds 20 parts by weight,
The resistance increases. Further, since the metal salt of fatty acid exceeds 2 parts by weight, the adhesion is poor. Furthermore, since the ratio of the epoxy emulsion exceeds 50% by weight, the drying property is poor.
In Comparative Example 3, since the acrylic emulsion was neutralized with an anionic amine, there were problems with the sedimentability of metal powder and the blue precipitate. At this time, even if a whisker of potassium titanate was attached, its sedimentation property and blue precipitate were not eliminated. Since the conventional examples 1 to 3 did not contain the epoxy emulsion, cracks occurred after drying.

[0025]

EFFECTS OF THE INVENTION Since the present invention is constituted as described above, there is a problem of working environment when using a conductive resin composition which has been a problem in the conventional conductive resin composition using a resin binder containing an organic solvent. (Poisoning due to organic solvent) can be solved and the working environment can be significantly improved, and cracks do not occur even if the coating film is thickened, so that the coating film can be thickened.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C09D 5/24 PQW C09D 5/24 PQW 133/00 PFW 133/00 PFW PGG PGG 163/00 PKE 163 / 00 PKE C09J 9/02 JAS C09J 9/02 JAS JAW JAW JBB JBB 163/00 JFP 163/00 JFP

Claims (3)

[Claims] 1. An acrylic emulsion and an epoxy emulsion using a polyester material as an emulsifier as a binder with respect to 100 parts by weight of metal powder, and a total solid content thereof is 12 parts by weight or more and 20 parts by weight or less, and a water-soluble dispersant. The saturated or unsaturated metal salt of 0.
A conductive resin composition obtained by kneading 1 part by weight or more and 2 parts by weight or less. 2. The conductive resin composition according to claim 1, wherein the metal powder is gold powder, silver powder or silver-plated copper powder, and the metal salt of the dispersant is sodium salt or potassium salt. . 3. The solid content mixing ratio of the acrylic emulsion and the epoxy emulsion is 85 wt% to 50 wt% of the acrylic emulsion and 15 wt% to 50 wt% of the epoxy emulsion. Conductive composition of.