JPH0611841B2 - Conductive epoxy resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] The present invention relates to a conductive adhesive composition that achieves strong adhesion while maintaining conduction between conductive members.

2. Description of the Related Art When assembling an electric component or the like, it is common to use welding or brazing to secure electrical conductivity of a member such as metal and at the same time fix it. However, a conductive adhesive or the like is used when it is desired to avoid heating, when it is not possible to use flux, or when a material such as solder is not used.

As such a conductive adhesive, there is one in which fine powder such as silver or nickel is dispersed in a thermosetting resin such as spoxy resin. However, since these metal powders are expensive, an inexpensive conductive material is used. It has been proposed to make a conductive adhesive by using, for example, a conductive adhesive in which a conductive carbon powder and an epoxy resin are mixed has been commercialized. However, conductive carbon powder is inferior to metal powder in terms of conductivity. When a large amount is added to increase the conductivity, the viscosity of the composition increases, and there is a problem that the processability during potting and the like deteriorates. Further, even after curing, there is a large change with time in the conductivity at high temperature. There are drawbacks.

Therefore, it was considered to use carbon fiber as the conductive material, but when the length of carbon fiber is long, a composition with good processability cannot be obtained, and even if it is crushed and used, reproducibility of processability and conductivity Is not sufficient, and an adhesive composition having conductivity that can withstand practical use has not been obtained.

Problems to be Solved The present invention has as its object to realize a conductive adhesive having excellent workability and conductivity, and having stable quality, by using a carbonaceous conductive material, particularly carbon fiber. .

[Structure of Invention]

Means for Solving the Problems The present inventor has conducted research on a carbonaceous conductive material, and as a result, found that the object of the present invention can be achieved by combining a specific carbon fiber and a conductive carbon powder. . That is, the conductive epoxy resin composition of the present invention,
10 to 200 parts by weight of vapor grown carbon fiber and 5 to 100 parts by weight of conductive carbon powder are mixed with 100 parts by weight of epoxy resin.

The epoxy resin used in the present invention may be a liquid resin that can be compounded without using a solvent, for example, an epoxy resin obtained by reacting epichlorohydrin with a bisphenol compound, a polyphenol compound, a polyhydric alcohol, or the like. Epoxy group-containing resins such as epoxidized polyolefin and epoxidized polybutadiene are used, but are not particularly limited.

The vapor-grown carbon fiber blended in the present invention is obtained by vapor-phase pyrolyzing a hydrocarbon compound in the presence of a catalyst in a non-oxidizing atmosphere. Such a vapor-grown carbon fiber is obtained by, for example, placing a carrier substrate on which fine particles of a transition metal such as iron or a compound thereof is attached as a catalyst in a mullite reaction tube installed in a horizontal electric furnace to obtain hydrogen gas or the like. Introducing a gaseous mixture of a carrier and a hydrocarbon compound such as ethane or benzene at a temperature of 1000 to 1400 ° C., thermally decomposing the hydrocarbon in contact with the substrate to grow carbon fiber, and recovering the carbon fiber. Obtained by Furthermore, a substrate such as ceramics containing silicon is placed in a similar reaction apparatus, and a carrier such as hydrogen and a hydrocarbon compound such as ethane and benzene and a sulfur-containing substance such as elemental sulfur, hydrogen sulfide, and mercaptan are included. A mixed gas or a mixed gas of a carrier such as hydrogen and a sulfur-containing hydrocarbon compound such as dibenzothiophene is introduced at a temperature of 1200 to 1400 ° C. to thermally decompose the hydrocarbon in contact with the substrate to form carbon fiber. It can also be obtained by growing and recovering this. Such a vapor-grown carbon fiber has a diameter of 10 depending on reaction conditions.
Although a product having a diameter of about μm and a length of several cm can be obtained, a material having a diameter of about 1 to 2 μm and a length of about 0.1 to 1 mm can be preferably used in the present invention.

Further, it is desirable that the conductive carbon powder to be blended with the vapor grown carbon fiber has a well-developed structure, and it is particularly preferable to use a highly conductive carbon black such as Ketjen Black (Lion Akzo Co., trade name). preferable. The particle size of such carbon powder is preferably about 10 to 50 μm.

Such vapor grown carbon fiber and conductive carbon powder,
10 to 20 for each 100 parts by weight of epoxy resin
It is preferable to be in the range of 0 parts by weight and 5 to 100 parts by weight, and further to the range of 30 to 90% by weight, and further 40 to 80% by weight of the carbon fiber with respect to the total of the carbon fiber and the carbon powder. Those in are preferred. If the amount of the carbon fiber or carbon powder in the composition of the present invention is too small, sufficient conductivity cannot be obtained, and if the amount is too large, the viscosity of the composition becomes high and the processability deteriorates.

In the composition of the present invention, a curing agent, a curing accelerator, a filler,
A diluent or the like can be added. Of these, amine-based curing agents are preferable as the curing agent, and the epoxy resin is appropriately selected from aliphatic amines, aromatic amines, complex amines, etc. according to desired curing conditions and physical properties of the cured product. It is suitable to use 3 to 150 parts by weight for 100 parts by weight.

Action The conductive epoxy resin composition of the present invention has good processability, is well compatible with the surface of a member to which it is applied, exhibits a strong adhesive force, and provides a cured product having excellent conductivity.

Example 1 Epikokuto 815 (Shell Chemical Co., trade name) was used as the epoxy resin, Ketjen Black EC (Lion Akzo Co., trade name) was used as the conductive carbon powder, and the following vapor phase growth carbon was used as the carbon fiber. The fibers FS and FF and the PAN-based carbon fiber pulverized product FN were mixed according to the compounding amounts shown in Table 1 and thoroughly kneaded, and then Epicure Z (trade name of Shell Chemical Co., Ltd.) was added as a curing agent to homogenize the mixture. By dispersing, a conductive epoxy resin composition was prepared.

Carbon fiber used FS: obtained by using sulfur and silicon catalyst (diameter: about 1 μm, length: about 0.3 to 0.5 mm) FF: obtained by using iron-based catalyst (diameter: about 1 μm , Length: about 0.3 to 0.5 mm) FN: Trading Card MLD-300 (trade name, Toray Co., Ltd.) (Diameter: about 7 μm, Length: about 0.3 mm) A parallel plate viscometer is used for these compositions. The easiness of flow was measured by using the results, and the results are shown in Table 1 as an index of workability.

Further, these compositions were thinly applied on a smooth glass plate so as to have a uniform thickness, heat-treated at 120 ° C. for 3 hours to be cured, and the results of measuring volume resistivity are also shown in Table 1. It was

Further, changes in the electric resistance with time when the above-mentioned cured product was heat-treated at 120 ° C. and 160 ° C. are shown as graphs in A and B of FIG. 1 and A and B of FIG.

From these results, the composition of the present invention retains excellent processability, but both the initial resistance value and the resistance value change rate are smaller than those of the composition containing FN, which is a PAN-based carbon fiber, It can be seen that it gives excellent conductivity.

Example 2 Commercially available conductive adhesive in which a mixture of epoxy resin with carbon black as a conductive filler and a mixture of polyamide resin as a curing agent with carbon black as a conductive filler are combined. The same carbon fibers and carbon powders as those used in Example 1 were mixed with the agents (Dautite A-3 and Dautite C-3, Fujikura Kasei Co., Ltd.) in the compounding amounts shown in Table 2, respectively. The mixture was kneaded sufficiently uniformly to prepare a conductive epoxy resin composition.

Table 2 also shows the workability measured in the same manner as in Example 1 and the volume resistivity measured in the same manner except that the heat curing condition was 150 ° C. for 30 minutes.

Further, changes in the electric resistance with time due to the heat treatment are shown in FIGS. 3 and 4.

These results show that the composition of the present invention to which the vapor growth carbon fiber is added is superior in processability and electrical properties to the composition containing FN which is a PAN carbon fiber and conductive carbon powder. It can be seen that it has characteristics.

[Effects of the Invention] As described above, the conductive epoxy resin composition of the present invention has low electrical resistance while maintaining fluidity that is easy to process, and the cured product has stable and excellent conductive properties even under high temperature conditions. And can be used as a highly reliable conductive adhesive or conductive paint.

[Brief description of drawings]

FIGS. 1 to 4 are graphs showing changes with time of electric resistance values when a cured product of a conductive epoxy resin composition is heat-treated.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location C09J 163/00 JFN 8830-4J

Claims (2)

[Claims] 1. A conductive epoxy resin composition comprising 100 parts by weight of an epoxy resin, 10 to 200 parts by weight of vapor grown carbon fiber and 5 to 100 parts by weight of conductive carbon powder. 2. The conductive epoxy according to claim 1, wherein the vapor grown carbon fiber is obtained by thermally decomposing a hydrocarbon compound in the presence of a catalyst in a non-oxidizing atmosphere. Resin composition.