JPS6116777B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a conductive resin composition having low resistance and excellent resistance stability. In recent years, as the density and performance of ICs and LSIs have increased, a large number of ICs and LSIs have come to be used in electronic devices. However, since these ICs and LSIs generate high-frequency pulses, surrounding televisions, radios, and peripheral equipment are affected by this, causing problems such as image distortion, noise, and malfunction. Furthermore, televisions, radios, etc. are similarly affected not only by high-frequency pulses from ICs and LSIs, but also by electromagnetic waves generated from automobiles, high-voltage lines, etc. As the electromagnetic environment deteriorates year by year, the need to shield electromagnetic waves is increasing. There are two methods for shielding electromagnetic waves: one is to apply conductive paint to the housing of an electronic device to protect it from electromagnetic waves entering from the outside, and the other is to suppress electromagnetic waves generated from the device itself. This conductive paint is made of nickel and carbon. The mainstream is one in which conductive powder such as silver is dispersed in resin. However, nickel powder is expensive and its conductivity is not very good. Carbon is cheap but has poor conductivity. Although silver powder has excellent conductivity, it has drawbacks such as being very expensive, and there is no balance between price and conductivity. On the other hand, copper powder has a good balance between conductivity and price. However, paints using copper powder have the disadvantage that the copper powder oxidizes during storage or after application, resulting in a high resistance value. As a method to prevent this oxidation, attempts have been made to add phosphoric acid compounds, benzotriazole, quinone compounds, etc. However, although these have good initial conductivity, their resistance value increases due to hygroscopic heating. It cannot be put to practical use. As a result of various studies, the present inventors found that 1,3,5-tris (4-t-butyl-3
- Hydroxy-2,6-dimethylbenzyl)isocyanuric acid can prevent copper oxidation,
It has been found that long-term resistance stability can be obtained even when heated and absorbed moisture. That is, the present invention provides (A) a thermofusible resin and/or a thermosetting resin, (B) copper powder, and (C) 1,3,5-tris(4-t-butyl-3-hydroxy-2,6 −
The present invention relates to a conductive resin composition containing dimethylbenzyl)isocyanuric acid. The thermoplastic resin that is component (A) of the present invention includes:
These include thermoplastic acrylic resins, vinyl resins, urethane resins, alkyd resins, polyester resins, hydrocarbon resins, fluoroelastomers, and cellulose resins. Thermosetting resins include thermosetting acrylic resins, unsaturated polyester resins, epoxy resins, urethane resins, alkyd resins, and the like. These resins may be used alone or in combination of two or more. The thermoplastic resin and the thermosetting resin may be used alone or in combination. The copper powder of component (B) preferably has a purity of 95% or more, more preferably 99% or more. Regarding the size of the copper particles of the copper powder, those having an average particle size of 200 microns or less can be used, but those of 50 microns or less are preferable. (A), (B) and (C) of the present invention, the blending ratio of the components is (A) component
Component (B) is preferably in the range of 50 to 2000 parts by weight per 100 parts by weight. If it is less than 50 parts by weight, the conductivity will decrease,
If it exceeds 2000 parts by weight, it tends to be difficult to form a paste. Component (C) is preferably 0.01 part by weight or more per 100 parts by weight of components (A) and (B). If it is less than 0.01 part by weight, the antioxidant effect will be low. In addition to components (A), (B), and (C) of the present invention, diluent solvents such as toluene, xylene, acetone, methyl ethyl ketone, methyl alcohol, ethyl alcohol, ethyl cellosolve, butyl cellosolve, and aliphatic solvents are generally used. You can use what is already in use. Fillers, pigments, etc. are used as necessary. As a filler, silicon oxide,
Calcium carbonate, magnesium carbonate, etc. can be used. In addition, when coloring, common pigments such as carbon black red iron and chromium oxide can be used. In addition to the copper powder of component (B), silver powder, carbon, nickel powder, copper-zinc alloy powder, etc. may be mixed and used. Next, the present invention will be explained by examples. Example,
Parts in the comparative examples are parts by weight. 1. Synthesis of thermoplastic acrylic resin A 250 parts of methyl methacrylate and 150 parts of toluene were placed in a four-necked separable flask (No. 1), and the temperature was raised to 90° C. while nitrogen gas was passed through the flask and kept warm. Add 200 parts of methyl methacrylate and 3 parts of azobisisobutyronitrile to this solution.
Polymerization proceeded by dropping the solution over time. then 110
Raise the temperature to ℃, keep it warm for 2 hours to complete polymerization, cool it and when it reaches 50℃, add 600 parts of toluene.10
The mixture was stirred for a minute to obtain a solution of thermoplastic acrylic resin A. Comparative Example 1 Varnish A was prepared by mixing and stirring 30 parts of the solution of acrylic resin A obtained in 1 and 70 parts of copper powder (350 mesh pass). Comparative Example 2 Varnish B was prepared by mixing and stirring 30 parts of the solution of acrylic resin A obtained in 1, 70 parts of copper powder (350 mesh pass), and 5 parts of phosphorous acid. Comparative Example 3 30 parts of the solution of acrylic resin A obtained in 1, 70 parts of copper powder (350 mesh pass), 5 parts of benzotriazole
The mixture was mixed and stirred to obtain Varnish C. Example 1 30 parts of the solution of acrylic resin A obtained in 1, 70 parts of copper powder (350 mesh pass), 1,3,5-tris(4-t-butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanur Varnish D was prepared by mixing and stirring 5 parts of acid. Example 2 30 parts of TF-1154 (toluene solution of thermosetting urethane resin manufactured by Hitachi Chemical Co., Ltd.), copper powder (350 parts)
Messiupas) 70 copies, 1, 3, 5-tris (4-
Varnish E was obtained by mixing and stirring 5 parts of t-butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanuric acid. Varnishes A to E created in the above comparative examples and examples
Spray onto a glass plate and dry at 25℃ for 24 hours.
A coating film of 100 x 10 x 0.2 mm was created. This test piece
The volume resistivity was determined after being left at 100°C/48 hours or 40°C/95%RH/48 hours. The results are shown in Table 1.

[Table] As is clear from Table 1, the conductive resin composition of the present invention shows no change in resistance even after heating and moisture absorption, indicating that there is no change in resistance due to oxidation.

Claims (1)

[Scope of Claims] 1 (A) Thermofusible resin and/or thermosetting resin (B) Copper powder and (C) 1,3,5-tris (4-t-butyl-3-
A conductive resin composition containing hydroxy-2,6-dimethylbenzyl)isocyanuric acid.