JPS59152935A - Electrically conductive composition - Google Patents

Abstract

PURPOSE:To provide an electrically conductive composition having excellent applicability, economicity, and properties as a paint or adhesive, and composed of a film-forming liquid resin composition and electrically conductive inorganic particles obtained by coating the surface of scaly non-metallic inorganic particles with an electrically conductive substance. CONSTITUTION:The objective composition is composed of (A) 10-60pts.wt. of electrically conductive inorganic particles obtained by coating the surface of scaly non-metallic inorganic particles (e.g. mica-group or orthoclorite-group minerals, etc.) with an electrically cnductive substance having a volume resistivity of <=1OMEGA.cm (e.g. silver, Al, Cu, graphite, etc.) and (B) 90-40pts.wt. (in terms of solid content) of a film-forming liquid resin composition (e.g. polyvinyl acetate, polyurethane resin, etc.). The amount of the electrically conductive substance is preferably 1/5-1 times weight of the inorganic particle.

Description

[Detailed description of the invention] The present invention relates to electrically conductive compositions. For more information.

The surface of the scale-like nonmetallic inorganic powder has a volume resistivity of lΩ・σ
Conductive inorganic powder 1 coated with the following conductive substance
The present invention relates to a conductive composition having excellent properties as a paint or adhesive, comprising 0 to 60 parts by weight and 90 to 40 parts by weight (in terms of solid content) of a liquid resin composition having film-forming ability.

In recent years, with the development of electronic devices, a new social problem called electromagnetic interference has arisen. This is a problem where the computer malfunctions due to various noises in various environments.
Nowadays, various devices are controlled by computers, which can lead to major accidents. In particular, due to the demand for lighter and more compact equipment, one of the problems is that most of the housings are made of plastic snacks, and in the United States, regulatory values such as the FCC have been established. As a countermeasure, we currently use 1) metal spraying and 2) conductive paint.

3) Three methods or materials have been used: plastics containing conductive fillers, but method 1) is expensive and may lead to electric shock or fire accidents due to peeling, so method 2) is gradually changing. It's coming. On the other hand, method 3) is also seen as promising, but at present no material has been developed that satisfies moldability and electromagnetic resistance. Therefore, method 2) is currently the most effective method for such applications, and involves dispersing fine metal particles or carbon particles in a liquid resin. It is used for barrier materials, electrode materials, antistatic materials, 1-resistance heating elements, etc. However, paints and adhesives containing metal particles dispersed with good electrical conductivity include silver, copper, silver-copper alloys, etc. as dispersed particles.
Nickel particles are the mainstream, are expensive, and are easy to settle and separate because a large amount of metal particles with a high specific gravity are added.

In addition, the processability is poor and adhesion failure is likely to occur, and metal particles migrate in the film. on the other hand,
In the case of the carbon particle dispersed type, the difference in specific gravity from the resin is small, and the above-mentioned problems are few, but one drawback is that it has poor conductivity and can only be used as an antistatic material or a resistance heating element.

In view of the above-mentioned current situation, the present inventor has conducted intensive research to develop an excellent conductive paint and conductive adhesive that improves the above problems, and as a result, has arrived at the present invention.

That is, the present invention provides (A) 10 to 604 parts by weight of a conductive inorganic powder, the surface of which is a scaly nonmetallic inorganic powder coated with a conductive substance having a volume resistivity of 1 Ω·m or less. and CB) Liquid resin composition 9 having film-forming ability
It is a conductive composition consisting of 0 to 40 parts by weight (in terms of solid content).

The conductive composition of the present invention has the characteristics described below and is used as a paint or adhesive. First, making only the surface of the scale-like nonmetal inorganic powder conductive is very effective in connecting conductive fillers, and compared to conventional ones, it has excellent conductivity with a small amount of addition. properties, and can exhibit excellent photoelectromagnetic resistance. Second, scale-shaped nonmetallic inorganic powder and granules.

Unlike mineral particles, they are scaly and lightweight, so there is no need to worry about sedimentation, and the dispersion is good. In particular, since the scaly powder is arranged in parallel during coating, it has excellent coating properties. Thirdly, since the obtained film is lightweight, it is effective when applied to electrical and electronic appliances, etc., where miniaturization and weight reduction have been emphasized in recent years. In addition, since large amounts of expensive metals such as chime are not consumed, it is advantageous in terms of resource saving and cost. ``!Ohki: Paints and adhesives made of the conductive composition of the present invention have the same adhesion to substrates and physical and chemical stability as a coating film, and have the same properties as those of conventional ones. In addition to the above-mentioned uses, it can be widely applied to fields where conventional products could not be used due to cost and processability.

The scaly nonmetallic inorganic powder used in the present invention includes:
Examples include mica, talc, sericite, glass flakes, layered graphite, vermiculite, bentonite, and attapulgite.

The scale-like inorganic powder preferably has a diameter of 0.1 to 500 μm and an aspect ratio of 10 or more from the viewpoint of coatability and physical properties of the coating film. In particular, natural minerals and artificial minerals belonging to the mica group, brittle mica group, or chlorite group and glass flakes are the most preferably used scaly nonmetallic inorganic powder particles,
Specifically, natural muscovite (muscovite), phlogovite (phlogovite), biotite (biotite), vermiculite (vermiculite), and synthetic mica containing fluorine and glass flakes for flake 2 innings can be mentioned. can.

6. As the conductive material that coats the surface of the scale-like inorganic powder, any conductive material having a volume resistivity of 1Ω・crn or less can be used;
Silver, copper, iron, nickel, aluminum,
tin, chrome, titanium.

For γ; 1, zinc, gold, platinum, their alloys such as kasuri, or graphite are suitable; especially when high conductivity is required, silver 1 copper and nickel are preferable, and antistatic materials and resistance heating materials are suitable. When used as a material, graphite is preferred. The amount of the conductive substance used for coating depends on the application, but is preferably 1 to 1 times the weight of the scaly nonmetallic inorganic powder. If the amount is less than twice the weight of the building, the conductivity will be poor, and if it is more than 1 times the weight, the conductive material will easily fall off, causing various troubles, as well as being disadvantageous in terms of price and weight. become. Any method may be used to coat the surface with metal or graphite.5 For example, the surface of the scaly inorganic powder is scattered in a metal salt compound solution of an appropriate concentration, and then the solution is reduced to form a scaly inorganic powder. Electroless plating method, vacuum evaporation method, sputtering method, ion blating method, etc., as described in 7. Methods for depositing metal particles on the surface of the grains, etc., can be used. Alternatively, it is also possible to use a method in which the surface of the scaly inorganic powder is coated with a suitable binder and then fine particles of a conductive substance are adhered thereto. The thickness of the coated conductive material is 100X to 1 μm,
Preferably H-to, os μm to 100 μm is desirable from the viewpoint of various performances.

The liquid resin composition having film-forming ability used in the present invention can be any of those commonly used as paints and adhesives, but in particular when used as a paint, 1-polyvinyl acetate, polyvinyl chloride, polyurethane can be used. Emulsion type resin compositions such as acrylic resin monovinyl chloride resin, polyurethane resin, epoxy polyamide resin,
Solution type resin compositions such as silicone resins, phenolic resins.

Melamine resin, area resin, epoxy resin, unsaturated yj
-' Thermosetting type or two-component type resin compositions such as IJ ester resin can be mentioned. Among them, epoxy-based
Polyurekne-based and acrylic-based resin compositions are preferred. On the other hand, when used as an adhesive = 8-, solution type resin compositions such as chloroprene resin and silicone resin, emulsion type resin compositions such as polyvinyl acetate, epoxy resin 1 unsaturated polyester resin, area resin, Examples include polycondensation type resin compositions such as phenol resins, cyanoacrylate resins, and inanate resins.

In particular, epoxy resin compositions are preferred. A mixture of these can also be used depending on the use and purpose.

The conductive composition of the present invention is prepared using: 10 to 60 parts by weight of the conductive scaly nonmetallic inorganic powder and 90 to 40 parts by weight (in terms of solid content) of the liquid resin composition.

If the content of the conductive scaly nonmetallic inorganic powder is less than 10 parts by weight, the conductivity will be poor, and if it is more than 60 parts by weight, the adhesion and strength of the film will be reduced. In the case of conventional conductive paints in which fine metal particles are dispersed, sufficient conductivity cannot be obtained unless 70 to 90% by weight of fine metal particles are added. This is one of the characteristics of the conductive composition according to the present invention. In addition, the conductive composition of the present invention further includes a scaly nonmetal-free 9
- Minor amounts of various additives such as dispersants for improving the dispersibility of milled powder particles and lubricants for improving dispersion stability and abrasion resistance of the coating may be used, and ordinary pigment additions may be used. The same materials used for mold paints and adhesives can be used.

The conductive composition of the present invention can be prepared by mixing and dispersing in the same manner as ordinary paints and adhesives, but when used as a paint, it is generally prepared by diluting with a solvent or using a liquid resin composition with a low degree of polymerization. It is common to prepare a low viscosity slurry using . However, when used as an adhesive, it is prepared in the form of a high viscosity paste.

When the conductive composition according to the present invention is actually used, the surface of the base material is first degreased and, if necessary, etched or primed, in the same way as general paints and adhesives, and then sprayed, roller, brushed, etc. Apply the specified amount with a spatula, etc. Especially in the case of spray coating, it is advantageous because the scale-like powder particles tend to be arranged parallel to the surface of the substrate. The thickness of the coating after drying or curing varies depending on the use and purpose, but -
lO- Generally, 5 to 100 μm is preferred.

Methods for directly evaluating the conductivity of a coating film obtained using the conductive composition of the present invention include 1, for example, lEC-93-1
There is a method of measuring the volume resistivity using a disk method based on 958, and a method of measuring the surface resistance between two points on the coating film. Generally, when a conductive composition is used as an electromagnetic barrier material, the volume resistivity of the material must be less than 1Ω・Fu, but when it is used as an antistatic material, , may be larger than 1Ω.sub.

The method for measuring the electromagnetic interference effect is based on the US FCC (Federa)
lCommunicationComm1g5lon
It is preferable to follow the method specified in 1), but for convenience, it is also possible to evaluate by the method described in, for example, pages 31 or 38 of "Kogyo Zaizai" Vol. 29, December issue. This method uses a motor or spark as the noise source, receives the signal with a dipole antenna, and detects it with a spectrum analyzer or field strength meter, but a quasi-peak detection method should be used for detection. .

As described above, the conductive composition according to the present invention has excellent conductivity when used as a paint or an adhesive, so (1) it can be used as an electrode connector for electronic components such as piezoelectric elements, photoelectric elements, and capacitors, etc. Electrode materials for (2) video games 1 electronic plate making machine, electronic typewriter 1 electronic time recorder, electronic desk calculator, electronic sewing machine 1 electronic register, microwave oven, personal computer, facsimile, copying machine, printer, VTR, plotter 1. Electromagnetic barrier material applied to the housings of electronic devices such as word processors, displays, ultrasonic diagnostic equipment, communication devices, 1. medical devices, measuring instruments, etc. (8)
Used in IC, LSI production plants, various factories such as oil refineries, coal mines, hospitals, etc., hoses, sheets, cables, conveyors, transport magazines, storage boxes, floor sheets, human body earth molded products, and tank trucks. Antistatic materials by applying to automobiles, aircraft, etc., (
4) It can be widely used as a resistance heating element for use in roofs, snow melting on runways, glass fogging, the body of thermistor, etc.

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to these Examples in any way. In the examples, all "parts" mean parts by weight unless otherwise specified.

Example 1, Comparative Example 1.2 Phlogopite powder having an average particle size of 45 μm and an average aspect ratio of 45 was subjected to sensitizing treatment with tin chloride.

Activation treatment was performed with palladium chloride, and then electroless plating was performed on the cloud and mother powder surfaces in an alkaline plating bath of nickel sulfate and sodium hypophosphite. The nickel content Vi in the obtained conductive powder is 35% by weight, which is 1 true north weight V! It was 1.9.

Furthermore, according to the results of observation using a scanning electron microscope, the thickness of the nickel coating film was approximately 0.4 μm, and the thickness of the nickel coating was approximately 0.4 μm.
The volume resistivity under a pressure of f/1-rA was less than 10 Ω·sub, and it had excellent electrical conductivity.

Next, 100 parts by weight of the conductive powder was added to 800 parts by weight of a commercially available acrylic clear paint (solid content: 32% by weight), dispersed and mixed to prepare conductive composition Gold 13-. The dispersibility was good, and no sedimentation separation due to standing was observed. The conductive composition prepared by such a method is
The coating was applied with a brush onto the surface of an etched ABS resin plate having a thickness of approximately 2W+, and after drying, a coating film having a thickness of approximately 50 μm was formed (Example 1).

Using the conductive composition-coated glass plate thus obtained, an electromagnetic interference effect measuring device similar to the method described in "Industrial Materials" Vol. 29, December issue, page 38 was prepared.
Use the motor as a noise source.

As a result of analysis using a spectrum analyzer, the shielding effect was 47 decibels for a frequency of 10 MHz, 40 decibels for a frequency of 100 MHz, and 43 decibels for a frequency of 1 gigahertz.

Using the same nickel-coated mica and acrylic clear paint as in Example 1, 20 parts by weight of the nickel-coated mica was added to 80 parts by weight of the acrylic clear paint (solid content: 32% by weight).
A conductive composition was prepared in the same manner as in Example 1 by adding 0 parts by weight.

A coating film of approximately 50 μm was formed in the same manner as in Example 1.
- (Comparative Example 1). When the electromagnetic interference effect was investigated at the above frequency, almost no effect was observed at 2 to 3 decibels. Furthermore, using the same nickel-coated mica and acrylic clear paint as in Example 1, the nickel-coated mica 440
The weight part is the acrylic clear paint (solid content 32% by weight)
800 parts by weight to prepare a conductive composition in the same manner as in Example 1.
A coating film of (Comparative Example 2) was formed. However, the resulting film was very brittle and the nickel-coated mica peeled off, making it unusable. As described above, it is clear that when the conductive composition according to the present invention is used as an electromagnetic barrier coating, it has excellent effects.

Example 2, Comparative Example 3 Phlogopite powder with an average particle size of 15 μm and an aspect ratio of 30 was subjected to the same electroless plating treatment as in Example 1, and a copper film with a thickness of 0.3 μm was deposited on the metal matrix surface. A conductive powder material having a surface coating of about 47% by weight was obtained.

The volume resistivity of the obtained conductive powder under pressure is lO
Atsu Buhi below Ω・α. Next, 250 parts by weight of a commercially available amine as a curing agent was added to 250 parts by weight of an FC 2-component epoxy resin, and 100 parts by weight of the conductive powder was dispersed and kneaded to prepare a conductive composition according to the present invention.

A film of (Example 2) was obtained. The volume resistivity of the film is 1
00.1 surface resistance was 0.5Ω. Also,
Using the same copper-coated mica and epoxy resin as in Example 2, 25 parts by weight of the copper-coated mica was dispersed and kneaded in 250 parts by weight of the epoxy resin to prepare a conductive composition. A film with a thickness of about 50 μm was obtained (Comparative Example 3).

The volume resistivity of the film was 10 Ω·α or less, and the 2-surface resistance was 10 10 Ω or more. As described above, it is clear that the adhesive made of the conductive composition according to the present invention has excellent conductivity.

Comparative Example 4 True specific gravity 1 instead of nickel-coated phlogopite in Example 1
Silver particles 1 with exactly the same mixing ratio using 0.5 silver particles
00 g (Okibe and commercially available acrylic clear paint (solid content 3
An attempt was made to prepare a conductive paint by dispersing and mixing 800 parts by weight of 2% by weight, but the sedimentation separation was severe and did not work. Further, when the tester was applied to the film obtained immediately after dispersion and dried, the needle did not waver at all. When the volume of the silver particles in the composition was calculated, it was found to be 4.6 volume units in the solid content. Thus, even if metal particles used in conventional conductive paints are mixed in the composition ratio according to the present invention, No conductivity can be developed.

Example 3 E-glass flakes having an average particle diameter of 230 μIn and an average aspect ratio of 60 were immersed in an acrylic resin hydrosol solution, and then dispersed and mixed in acetylene black, which is conductive graphite fine particles, in a semi-dry state.

Graphite-coated conductive glass flakes were obtained by drying in hot air while separating excess acetylene black.

The true specific gravity of the resulting conductive powder was 1.6, and the amount of acetylene black deposited was about 20 weight tq6. Next, 100 parts by weight of the conductive powder was dispersed in 17-285 parts by weight of a commercially available PVC resin paint (solid content: approximately 25 cm).
The mixture was mixed to obtain a conductive composition containing 58% by weight of the conductive powder in terms of solid content. When the conductive composition was applied to the paper outlet of a diazo copier, it was found that the clinging of the paper due to static electricity was completely eliminated and the composition could be used as an antistatic material.

Patent applicant: Rishi Co., Ltd. Representative Patent Attorney Ken Honda 18-

Claims (1)

[Scope of Claims] (1) (A) 10 to 60 parts by weight of a conductive inorganic powder or granule obtained by coating the surface of a scaly nonmetallic inorganic powder with a conductive substance having a volume resistivity of 1Ω·σ or less and 1(B) a conductive composition comprising 90 to 40 MR parts (in terms of solid content) of a liquid resin composition having film-forming ability. (2) The scale-like nonmetallic inorganic powder is a powder whose surface is coated with an electrically conductive material in an amount equal to 1 times the weight of the scale-like nonmetallic inorganic powder. ratio) 10
The conductive composition according to claim (1) or (2), which is the above powder or granule. (4) Claims (1), (2), or (8), wherein the scaly inorganic powder is a natural or artificial mineral belonging to the mica group, brittle mica group, or chlorite group. 1- The conductive composition according to item 1. (6) The conductive composition according to claim (1), (2) or (8), wherein the scaly inorganic powder is a glass flake. (6) A patent claim in which the conductive substance is an elemental metal or an alloy containing at least one metal selected from silver, aluminum, copper-nickel, chromium, titanium, tin, antimony, zinc, gold, platinum, and iron. Range items (1) and (2)
The conductive composition according to item (3), item (4), or item (6). (Te) Claim No. 1 in which the conductive substance is graphite
) Ring 1, term (2), term (8), term (4) or term (
6) The conductive composition according to item 6).