JPS62141067A - Electrically conductive resin composition - Google Patents

Abstract

PURPOSE:To provide an electrically conductive resin compsn. having excellent dispersibility, storage stability, surface resistance stability, etc., by incorporating metallic powder, an inorg. oxide and an organoboron-nitrogen coupled material in a synthetic resin. CONSTITUTION:1-2mol of an alcohol such as ethyl alcohol is reacted with 1mol of boric acid to obtain a semipolar compd. such as glycerol monolauroyl glycerol borate, which is then reacted with an amine compd. (e.g., triethanolamine) to obtain an ampholytic organoboron-nitrogen coupled material. 60-90wt% (based on the amount of a synthetic resin such as an acrylic resin) copper powder having an average particle size of 10mum or below, 0.5-5wt% (based on the amount of copper powder) inorg. oxide such as TiO2 and 0.5-5wt% (based on the amount of metallic powder) said organoboron-nitrogen coupled material are dissolved in a soln. of the synthetic resin in toluene.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a conductive resin composition having excellent conductive powder dispersibility and conductive stability.

[Technical Background of the Invention and Problems thereof] In recent years, many ICs and LSIs have been used in electronic devices, and digital signal processing has come to be performed functionally. On the other hand, the high-frequency pulses generated by the electronic device leak electromagnetic waves to the surrounding area and cause trouble to other electronic devices.

One of the reasons why this problem cannot be ignored is that the housings of electronic devices such as CDs have changed to plastic to make them lighter. Therefore, a technology is being developed to prevent the above-mentioned problems by processing the plastic box to 1 m long, and the usual method is to apply a conductive paint to the surface of the plastic box. In addition, as another use of conductive resin compositions, highly productive adhesives such as crimping and soldering (J etc.) are often used instead, and when electrical conductivity or thermal conductivity is required at the bonding point, metal Conductive adhesives and thermally conductive adhesives mixed with a large amount of powder are used.

These electrically conductive and thermally conductive powders are mainly metal powders, and in order to make them uniformly dispersed in the resin, they are dispersed using a mixer such as a dispersion mill or colloid mill. Another disadvantage is that uniform dispersion cannot be easily obtained because the materials are placed together. Further, even if the material is uniformly dispersed using a mixer, there is a drawback that the electrically conductive and thermally conductive particles settle to the bottom of the container over time. Once settled, it aggregates tightly, and when used as a paint, it is not easy to break it up and redisperse it.

Further, copper powder is particularly frequently used as a conductive powder, but when used as a paint or adhesive, the surface of the copper powder is oxidized by moisture etc., resulting in an increased resistance value and instability. As a result, the electrically conductive resin composition has the disadvantage that its electrical conductivity decreases and deteriorates over time.

Conventionally, in an attempt to improve these, a method has been proposed in which metal powder is coated with alkyl fatty acids (Japanese Patent Application Laid-Open No. 135495/1983), 4.
Adding a cationic antistatic agent to the electrostatic powder (Japanese Patent Application Laid-Open No. 58-32668@), Organic Titanate I
13. J: Method of adding fine silica (Unexamined Japanese Patent Publication No. 1983-
No. 36553) etc. have been proposed. However, none of the conventional methods are sufficiently effective, and there has been a demand for the development of materials with good dispersibility and conductive stability.

[Object of the Invention] The present invention solves the drawbacks of navigation and meets the needs! The purpose was to improve the dispersion of conductive powder.
It is an object of the present invention to provide a conductive (thermal conductive) resin composition that has excellent conductivity stability even against changes over time.

[Summary of the Invention] As a result of intensive studies to achieve the above object, the present inventors have found that by blending an organic boron-nitrogen bond, the conductive powder can be dispersed well and oxidized. As a result, it was discovered that a resin composition with excellent conductivity stability even against changes over time could be obtained, and the present invention was completed. That is, in the present invention, metal powder and R-free synthetic resin are added.
This is a conductive resin composition characterized by containing an Fa compound and an organic boron-nitrogen bond.

Examples of the synthetic resins used in the present invention include acrylic resins, styrene resins, vinyl resins, alkyd resins, urethane resins, epoxy resins, polyester resins, butyral resins, and unsaturated polyester resins, which may be used alone or in combination of two or more. Mix and use. These synthetic resins may be either liquid or solid, and when used, they are dissolved in an organic solvent.

The organic boron-nitrogen bond used in the present invention is produced by making an organic anode semipolar compound of boron formed from an alcohol and boric acid, and then reacting it with a nitrogen-containing compound such as an amine compound to form an ambipolar compound. 1!7ru. Specifically, first, 1 mol or 2 mol of alcohol and 1 mol of boric acid are reacted to form, for example, glycerin monolauroyl glycerin borate, glycerin monobalmitoyl glycerin borate, bis(monolauroyl glycerin,)bora-1. , bis(polyoxyethylene diglycol) borate, bis(stearoylglycerin) borate, di(
glycerin) borate poly(24m01) oxyethylene ether, di(glycerin) borate-1-poly(24m
ol) Semipolar compounds such as oxyethylene ether monostearate are obtained.

Then, by reacting these compounds with an amine compound, a -C1 complex exhibiting heat-resistant bipolar properties is formed. This complex has an excellent surface-active effect and improves the dispersibility of the conductive powder.

Specific examples of these organic boron-nitrogen bonds include BN-11, BN-13, and B manufactured by Toho Chemical Industry Co., Ltd.
Examples include N-1000.

The alcohol used here is a monohydric to trihydric alcohol, such as ethyl alcohol, butyl alcohol, cetyl alcohol, ethylene glycol, glycerin, butanediol, butoxypolyethylene glycol, polyoxyethylene, glycol monopropyl, and the like. The amine compound is preferably a tertiary amine, such as triethanolamine, jetanolstearoamine, monophenyldipropylamine, 1-liprobylamine, stearodibutylamine, and the like.

The amount of organic boron-nitrogen bond added to the metal powder is 0.
．． 5 to 5% by weight is desirable; if it is less than 0.5% by weight, there is no effect on dispersibility, prevention of sedimentation and agglomeration, and prevention of inhibition of conductivity, and if it exceeds 5% by weight, the effect will not improve any further and the conductivity will be adversely affected. It is undesirable because it interferes with sexuality.

Examples of the metal powder used in the present invention include nickel powder, copper powder, silver powder, aluminum powder, stainless steel powder, nickel- or tin-plated carbon powder, and these can be used alone or in a mixture of two or more.

These metal powders are used after being reduced to an average particle size of 10 μm or less by electrolysis, pulverization, or the like. The blended product of metal powder is 60 to 90% by weight with respect to the synthetic resin, and if it is outside this range, stable conductive stability cannot be obtained.

Examples of the inorganic oxide used in the present invention include fine powders of fumed silica, titanium oxide, magnesium oxide, etc., and these may be used alone or in a mixture of two or more.

This compounded product is 0.5% of the metal powder because it does not inhibit conductivity and is sufficient to prevent sedimentation when metal powder with a large true specific gravity is dispersed in a solution. ~5% by weight.

The dispersion effect in the present invention is due to the action of bipolar electroactive sites, which are organic boron-nitrogen bonds, on the inorganic oxide and metal powder, and the inorganic oxide covers the surface of the metal powder, resulting in a light powder with a fume-like appearance. This takes advantage of the fact that inorganic oxides such as silica have the property of dispersing and floating in resin solutions. In addition, the alkyl component of the bond that acts on the surface of the metal powder has an affinity with the resin solution, facilitating the dispersion of the metal powder.

The conductive resin composition of the present invention is prepared by thoroughly dispersing and dissolving conductive substances such as metal powder, inorganic oxide, and organic boron-nitrogen bond in a system in which a synthetic resin is dissolved in an organic solvent. However, the organic solvent used here may be one that dissolves the synthetic resin, and generally toluene,
Methyl ethyl ketone, butyl acetate, ethyl cellosolve, etc. are used.

[Embodiments of the invention] Next, the present invention will be specifically explained using examples.

The present invention is not limited to the following examples.

Examples 1 to 4 According to the composition shown in Table 1, toluene:butanol=
5: A solution of polymethyl methacrylate resin dissolved in a mixed solvent of 2 (by weight) was mixed with commercially available nickel powder as a metal powder, and then BN-11 < Toho Chemical Industries, Ltd. as an organic boron-nitrogen bond was added. (trade name) and stir thoroughly with a high-speed stirrer. Next, fumed silica was added and stirring was continued to prepare a conductive paint in which metal powder particles were sufficiently dispersed.

Examples 5-8 To 100 (l) of dicyandiamide and 0.3 kg of methyl ethyl ketone, 1 part of bisphenol A solid epoxy resin
Copper powder and organic boron-nitrogen bond BN-13 (manufactured by Toho Chemical Industry Co., Ltd., trade name) were added to the solution in which 1 kg of copper powder was dissolved, and the mixture was sufficiently stirred with a high-speed stirrer.

Furthermore, magnesium fine powder was added and stirring was continued, and SI
A conductive paint in which powder A was sufficiently dispersed was prepared.

Comparative Example 1 A conductive paint was prepared in the same manner as Examples 1 to 4 using the composition shown in Table 1.

Comparative Example 2 A conductive paint was prepared in the same manner as Examples 1 to 4 with the composition shown in Table 1.

Using the conductive paints prepared in Examples 1 to 8 and Comparative Examples 1 to 2, the dispersibility (sedimentability) and surface resistance of the coating films were measured. In the dispersibility test, conductive +Ii paint was placed in a 100 ml measuring cylinder, the sample was capped and allowed to stand, and the depth of the supernatant on the graduated cylinder was measured after a certain period of time to evaluate the dispersibility. The surface resistance was determined by brushing a conductive paint onto a glass plate to a thickness of about 50 μm, and leaving it to volatilize the solvent for 12 hours to form a paint film. The electrical resistance of the surface of this coating film was measured using a commercially available resistance measuring device.

[Effects of the Invention] As is clear from the above description and Table 1, the conductive resin composition of the present invention has good dispersibility and excellent conductivity against changes over time.

As a result, the composition did not have conductive substances settling and solidifying on the bottom of the container during storage, and the surface resistance was stable and showed little change, demonstrating the remarkable effects of the present invention.

Claims (1)

[Claims] 1. A conductive resin composition comprising a synthetic resin containing a metal powder, an inorganic oxide, and an organic boron-nitrogen bond.