JPH077616B2 - Conductive composite material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a conductive composite material which is particularly preferably used for a transparent conductor and a high frequency circuit board.

[Conventional technology]

Among the polymer films or sheets provided with a conductive film on the surface thereof, those which are entirely transparent are useful as transparent conductors. That is, the transparent conductors are used in transparent electrodes of various display elements such as liquid crystal display elements and electroluminescence display elements, and resistance heating elements used for antifogging window glasses of automobiles and aircraft.

By the way, most of the materials conventionally used as transparent conductors are those in which a metal oxide transparent conductive film such as a tin oxide film or an indium oxide film is formed on a glass substrate.
However, there is a limit to the large area of glass, and the thickness is at most 0.3 m.
It can only be thinned up to about m, is heavy, is brittle and easily broken, and has poor workability such as punching and cutting.
There is also a drawback in continuous productivity.

Therefore, in recent years, a transparent conductive film using a polymer film or a sheet (hereinafter, both are abbreviated as a film) as a substrate instead of glass has begun to be developed. The transparent conductive film using this polymer film as a substrate is thin, light, does not break, is flexible, has good processability, can be made into a large area, and has excellent continuous productivity. Has various features. A polyester film such as polyethylene terephthalate is known as a polymer film used as a substrate for the transparent conductive film. However, the polyester film is easily attacked by a strong acid or a strong alkali and may absorb water to cause hydrolysis. Especially when the transparent conductive film is used for a display application, it is necessary to pattern the conductive film into a predetermined shape, and a photo-etching method has been conventionally used. As such, the lack of alkali resistance is a serious drawback. Further, when forming a thin film by a vacuum vapor deposition method or a sputter method, it is difficult to raise the degree of vacuum of the moisture in the polyester, and it takes a long time to reach the desired degree of vacuum, resulting in poor productivity. There is a problem that makes it difficult to control the degree of oxidation.

Another application of the composite material in which a conductive film is provided on the surface of a polymer film is an electric circuit board, and an electric circuit board for high frequency is particularly expected. That is, when an electromagnetic wave is used for communication, a wider frequency band can be obtained by using a higher frequency wave, and thus a larger amount of information can be transmitted. Further, as the frequency becomes higher, the wavelength becomes shorter in inverse proportion to it, and as a result, there is an advantage that a small size and high performance antenna can be manufactured.

By the way, for a substrate of such an electric circuit for high frequencies, a material having a small dielectric constant and a small dielectric loss and high heat resistance is required. That is, at high frequencies, the propagation speed of an electric signal becomes faster as the inductivity of the circuit board becomes smaller, and the attenuation of the electric signal becomes smaller as the dielectric loss of the circuit board becomes smaller. Therefore, a material with a smaller dielectric constant and dielectric loss can achieve higher speed and higher SN. Further, in the process of manufacturing an electric circuit, a temperature of more than 200 ° C. is required for solder dipping or soldering work, so heat resistance that does not deform even under such temperature is required.

Under such circumstances, substrates using various materials are currently proposed, for example, substrates made of fluorine resin, epoxy resin, polyimide, polypropylene or the like. However, the fluorine resin has problems that it has poor adhesion to the metal that forms the conductive layer, has low rigidity, and is extremely expensive. Epoxy resin or polyimide has been conventionally used as a circuit board for low frequencies and medium frequencies, but it is not suitable for high frequencies because its dielectric constant and dielectric loss are too large. Polypropylene has excellent dielectric constant and dielectric loss, but lacks heat resistance and is apt to be deformed.

As described above, conventionally proposed high frequency electric circuits have advantages and disadvantages, and none have been known to exhibit excellent performance in all aspects.

[Problems to be solved by the invention]

Therefore, the present inventors have studied to provide a transparent conductive film excellent in mechanical properties, optical properties, electrical properties, thermal properties, and chemical properties and an electric circuit board suitable for high frequency, and as a result, It has been found that the use of specific polymers for the substrate can achieve the purpose.

[Means for solving problems]

That is, the present invention is a polymer obtained by hydrogenating a ring-opening polymer consisting of tetracyclododecene or its derivative: 50 to 100 mol% and norbornene or its derivative: 0 to 50 mol%. The conductive composite material is characterized in that a conductive organic film or metal film is provided on the surface of the sheet or film.

[Action]

The polymer constituting the sheet or film (hereinafter abbreviated as “film”) which is the substrate of the conductive composite material of the present invention is a homocyclic ring-opening polymer of tetracyclododecene or its derivative or tetracyclododecene and norbornene or its A polymer obtained by hydrogenating any ring-opening polymer of the derivative and the ring-opening copolymer. Therefore, the skeleton of the polymer does not substantially contain an unsaturated bond based on ring-opening polymerization, and thus has chemical resistance, solvent resistance, oil resistance and oil resistance higher than those of the polymer before hydrogenation. It has excellent heat resistance and weather resistance.

A commercially available product may be used as the raw material monomer for the hydrogenated polymer, but the miscellaneous monomer contained in the commercially available product may hinder the polymerization of the intended polymer, and thus it may be purified as necessary. Is preferred. Further, in particular, tetracyclododecenes may be difficult to obtain, and in that case, U.S. Pat. No. 3557072, JP-B-46-14910, JP-A-57-15.
It may be synthesized by the method disclosed in 4133 or the like.

Techniques for producing a ring-opening polymer by polymerizing tetracyclododecenes and norbornenes are already known. For example, the method disclosed in JP-B-46-14910 and JP-A-58-127728 is used. Can be adopted. From the viewpoint of heat resistance, the proportion of tetracyclododecenes in the ring-opening polymer is usually 30 mol% or more, preferably 50 mol% or more, and particularly preferably 70 mol% or more. The proportion of norbornenes in the ring-opening polymer is usually less than 70 mol%, preferably 50
It is less than 30 mol%, especially less than 30 mol%. The molecular weight is adjusted by adding olefins as described in JP-A-58-127728, but it is generally 100 to 100,000, preferably 10,000 to 500,000. The melt flow index MFR (260 ° C, 2.16 kg), which is an index of fluidity, is 0.001 to 1
000, preferably 0.05 to 200, particularly preferably 0.1 to 100 g /
It is in the range of 10 min.

The hydrogenation reaction of the ring-opening polymer is carried out by an ordinary method, and depending on the type of catalyst, it is carried out in a homogeneous or heterogeneous system under a hydrogen pressure of 1 to 150 atm in a temperature range of 0 to 180 ° C., preferably 20 to 100 ° C. Done. Then, the hydrogenation rate can be arbitrarily adjusted by changing the hydrogen pressure, the reaction temperature, the reaction time, the catalyst concentration and the like.

The hydrogenation catalyst may be any as long as it is used in the hydrogenation of an olefin compound, for example, nickel, palladium, platinum, or these metals as a heterogeneous catalyst, carbon, silica, diatomaceous earth, alumina. Examples of the catalyst include nickel / silica, nickel / diatomaceous earth, palladium / carbon, palladium / silica, palladium / diatomaceous earth, and palladium / alumina supported on a carrier such as titanium oxide. Further, as the homogeneous catalyst, nickel such as nickel naphthenate / triethylaluminum, cobalt octenoate / n-butyllithium, nickel acetylacetonate / triethylaluminum, a cobalt compound and an organometallic compound of Group I to III metal of the periodic table And Rh compounds and the like.

In order for the hydrogenated ring-opening polymer to exhibit the above-mentioned various properties, 80% or more, preferably 90% or more, particularly 95% or more of the unsaturated bond portion in the polymer main chain is hydrogenated. Should be. Further, when the hydrogenation rate is 80% or more, particularly 90% or more, the polymer has a solubility parameter (SP value) different from that of the polymer before hydrogenation, and the effect of improving the organic solvent resistance is also exhibited. Further, from the viewpoint of moisture resistance, it is desirable that the hydrogenated product has no polar group.

To produce a film as a base material, the ring-opened polymer hydrogenated product can be molded by various known methods such as extrusion, injection, compression, and wet cast. At the time of this molding, various compounding agents usually used for resins may be added if necessary. Further, the obtained film may be subjected to a stretching treatment such as uniaxial stretching, simultaneous biaxial stretching or sequential biaxial stretching to further enhance the strength and the like.

When a film is produced using the hydrogenated product of the ring-opening polymer as a raw material, a uniform transparent film is obtained without decomposition and gelation. These usually show a light transmittance of 85% or more, and often 90% or more.

For high frequency substrate applications that do not require transparency, the polymer may be used in an amount of 50 wt% or less (polyethylene, polypropylene, poly-4) unless the properties are impaired.
-Methylpentene-1) may be blended.

The conductive film provided on these films is an organic film or a metal film (Cu, Al, N) made of a conductive polymer (polyacetylene, polypyrrole, polypyridine, polyaniline, etc.).
i, Au, Ag, etc.), which are adhered as a sheet, a film, a foil, or laminated on the film by means of plasma polymerization, sputtering, vapor deposition, plating or the like.

For example, when used for a high-frequency circuit board, this conductive film can take the form of a composite layer of usually only the front surface of the polymer film, two layers of the front surface and the back surface, and three or more layers formed inside. The circuit can be formed by various known lithographic methods, for example, an etching method. Also,
As another method, a paint comprising a polymer component containing the polymer of the present invention or an unsaturated carboxylic acid modified product of the polymer of the present invention and a conductive material (metal, organic substance) is formed (conductive paint), and a screen is formed. A circuit can be formed by a printing method or the like. Of course, it is also possible to form a circuit of conductive paint and then form a higher conductivity circuit by a method such as electroless plating.

Further, an adhesive layer may be interposed between the polymer layer and the conductive film (metal, polymer, organic material, conductive paint, etc.). Examples of the adhesive layer include heat resistant resins such as epoxy resin, polyimide, polybutadiene, phenol resin, and polyether ether ketone. Of these, polyimide and epoxy resins are preferable because they are excellent in heat resistance, dielectric properties at high frequencies, and adhesiveness to metals. When interposing such an adhesive layer, it should be noted that the dielectric properties of the circuit board depend on the thickness ratio of the polymer layer and the adhesive layer. That is, in the case of (thickness of polymer layer) <(thickness of adhesive layer), the dielectric property of the circuit board is largely affected by the dielectric property of the adhesive layer and deteriorates as a whole. Of course, in the case where the frequency is moderately high depending on the application and the dielectric properties are not strictly demanded, but rather the adhesive strength with the conductive film on the surface layer is required, the thickness of the adhesive layer is compared. It does not matter if it is thickened. However, in order to exhibit good dielectric properties for high frequencies, it is preferable that the ratio of the thickness of the polymer layer / the thickness of the adhesive layer is 2 or more, particularly 3 or more. Further, this thickness ratio can be applied to the total thickness of each layer also in the case of a plurality of laminated bodies described later.

Alternatively, a high molecular weight polymer of the above-mentioned polymer ([η] 0.3 or more) that constitutes the substrate as a laminated layer and an α, β-unsaturated carboxylic acid, its anhydride, ester or the like are graft-copolymerized to the above-mentioned polymer. It is preferable to use a polymerized product because it does not change the dielectric properties of the substrate.

As another aspect of the present invention, a heat-resistant and insulating fibrous material may be mixed as a reinforcing material in the polymer layer and / or the adhesive layer. Examples of such reinforcing fibrous materials include quartz fibers, glass fibers, aromatic polyamide fibers, short fibers such as high-strength and high-elasticity polyethylene fibers, knitted fabrics, nonwoven fabrics, and the like.

As another aspect, the circuit board may be formed in the form of a laminate in which a plurality of polymer layers and adhesive layers are combined. In this case,
Each layer may be preferably laminated in the range of 2 to 30 layers.
If necessary, the fibrous material may be mixed in each layer or a part of the layers as described above.

In still another embodiment, the polymer layer may be crosslinked with a crosslinking agent. The crosslinking agent forms a three-dimensional structure by heating, irradiation with radiation, etc., and further improves the thermal characteristics and dimensional stability of the polymer layer. Various known crosslinking agents can be used, and examples thereof include divinylbenzene, diallyl phthalate, ethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, triallyl isocyanurate, and liquid polybutadiene.

When using the composite material of the present invention as a transparent conductive sheet, the visible light transmittance as a conductive film, that is, the value measured according to JIS K6714 is 50% or more, particularly 70% or more, and the specific resistance is 100 Ωcm or less, In particular, use the one of 50 Ωcm or less. More specifically, metal thin films such as Au, Ag, Cu, Pt, Cr and Rh, In ₂ O ₃ (Sn), SnO ₂ (Sb), SnO ₂ (Fe), CdO, Cd
₂ O ₃ , CdSnO ₄ , TiO ₂ , ZrO ₂ , CuI and other semiconductor and oxide semiconductor thin films, TiOx / Ag / TiOx (x ≦ 2) and other multilayer thin films,
Examples thereof include a polymer electrolyte thin film system such as polyvinylbenzyltrimethylammonium chloride and oligo (poly) styrenesulfonate, and a conductive polymer such as polyaniline, polythiophene, and polypyrrole. These conductive films are laminated on the polymer film by a well-known method like the above-mentioned high frequency circuit board. The conductive polymer can also be formed inside the film by an electrolytic polymerization method or a gas phase method. Also, TTF
It is also possible to express conductivity by impregnating a complex such as -TCNQ (tetrathiofulvalene-tetracyanoquinodimethane).

〔The invention's effect〕

As described above, the conductive composite material of the present invention is excellent in transparency, shows strong resistance to acids and alkalis, is excellent in solvent resistance, has good workability and can be made large in area. It has various features such as light weight, high flexibility, thin film formation, excellent heat resistance, excellent heat aging resistance, light stability, and excellent electrical characteristics.

Therefore, when it is used for a high-frequency electric circuit board, (i) the propagation rate of the high-frequency electric signal is high because the inductivity is small, and the attenuation of the electric signal is small because the dielectric loss is small, so that the speed of information transmission is increased. Can be realized, and highly sensitive reception of weak signals can also be realized.

(Ii) Since it has high heat resistance, it is not deformed by being softened or melted in the heat processing step in the production of a circuit board. Therefore, the thickness of the circuit board can be accurately controlled.

(Iii) It has excellent solder resistance.

(Iv) The water absorption is small, and excellent electrical properties can be stably exhibited over a long period of time.

(V) Excellent dimensional stability.

It has the following features.

Therefore, it can be used for various circuit boards, flat antennas, housing-integrated boards, flexible boards, and the like.

The transparent conductive film can be used for the following purposes. That is, if necessary, a thin film of a photoconductor or derivative such as polyvinylcarbazole or cadmium sulfide is formed on the conductive film, and electrophotographic recording applications such as OHP, second original drawing, slide film, microfilm, and EL (electroluminescence) are performed. Sensor), liquid crystal, electrochromic display, electrophoretic display and other solid-state display applications, thermoplastic coating, optical memory applications such as ferroelectric memory, terminal equipment such as transparent tablets, meters windows, TV CRTs, clean room It is suitable for windows and floors, semiconductor packaging materials, electromagnetic wave shielding applications, solar cell windows, photoelectric conversion elements such as optical amplifiers, heat ray reflection applications, and surface heating elements such as defrosters for automobiles and aircraft.

〔Example〕

Reference Examples 1-6 Methyltetracyclododecene And methyl norbornene And in the presence of a solution of ruthenium chloride (RuCl ₂ · 3H ₂ O) in n-butanol at about 100 ° C in a glass ampoule at about 3 ° C.
After reacting for a time, the product was washed with tetrahydrofuran and methanol and dried.

Next, the produced polymer is dissolved in tetrahydrofuran and hydrogen pressure is 50 kg / cm ² · G in the presence of a palladium / silica catalyst.
After stirring at 10 ° C for 30 minutes, the temperature was raised to 50 ° C and stirring was continued for 18 hours. The obtained precipitated product was dissolved in cyclohexane, filtered through a filter, reprecipitated with methanol and dried.

The hydrogenation rate of the obtained polymer was determined by NMR spectrum and Tg was D
The light transmittance was measured according to JIS K6717 and the water absorption was measured according to JIS K6911 by SC. The results are shown in Table 1.

Next, various conductive composite materials were prepared using these polymers, and they were evaluated as a transparent conductive film or a high frequency circuit board. An example is shown below.

Example 1 Using the polymer obtained in Reference Example 2, the thickness was measured by a T-die.
A transparent film having a width of 0.1 cm and a width of 20 cm was formed.

With a 2-pole magnetron sputter (Nichiden Anelva),
A high-frequency power supply of 13.56MHz is used, the substrate temperature is 50 ° C, the target is an In ₂ O ₃ / SnO ₂ = 90/10 (%) alloy target,
Under Ar gas inflow, sputter pressure 1 × 10 ^-2 Torr, RF output 50
An ITO film was formed at W and a sputter speed of 250Å / min. The film performance is ITO film thickness 3000 Å measured by Tile step (Taylor Hobson), specific resistance 2 × 10 ^-3 Ωcm measured by four-point probe method, and light measured by self-spectrophotometer UV365 (Shimadzu Corporation). The transmittance (400 nm to 750 nm) was 80%, and a good conductive film was obtained. Moreover, there was no change even after irradiation with a carbon arc lamp for 35 hours.

Example 2 Using the polymer obtained in Reference Example 6, the thickness is 0.1 mm and the width is 20 cm.
The film was molded.

The target is CdO ₂ / SnO ₂ = 2/1 (weight ratio), the reaction gas is O
₂ / Ar = 5/95 (%), sputter pressure 2 × 10 ^-2 Torr, RF output
A TO film was formed at 50 W and a sputter speed of 200 Å / min. As a result, conductive layer film 2500Å, light transmittance 83%, resistivity 3 × 10 ^-3
A transparent conductive film of Ωcm was obtained. Moreover, there was no change even after irradiation with a carbon arc lamp for 35 hours.

Example 3 Using the polymer shown in Reference Example 4, electrolytic polymerization was carried out under the following conditions. A polymer film (10 μm thick) was heat-pressed onto both sides of a platinum electrode (5 × 5 cm), and this electrode was used as an anode and a platinum plate was also used as a cathode. As an electrolyte solution, an acetonitrile solution of pyrrole and tetraethylammonium salt (BF) was used, and electrolytic polymerization was performed at an applied voltage of 2.1 V for 1.5 minutes. The transparent conductive film thus obtained had a light transmittance of 60% and a specific resistance of 35 Ωcm. Moreover, there was no change even after irradiation with a carbon arc lamp for 35 hours.

Comparative Examples 1 to 3 Using the polymers shown in Reference Examples 1, 3 and 5, Reference Example 1
The polymer of Example 1 was prepared in the same manner as in Example 1, the polymer of Reference Example 3 was prepared in Example 3 and the polymer of Reference Example 5 was prepared in the same manner as in Example 2. Then, it was irradiated with a carbon arc lamp for 35 hours. Each transparent conductive film turned yellow and its specific resistance decreased.

As can be seen from the above examples, the transparent conductive film of the present invention shows stable properties for a long period of time, but the one using the ring-opening polymer before hydrogenation as in Comparative Example is long in light. It can be seen that discoloration occurs over time and it cannot withstand long-term use. The same result was obtained even when heat was applied for a long period of time instead of light. Therefore, the transparent conductive film using the ring-opening polymer before hydrogenation is transparent to liquid crystal display devices, which is a specific application of the film. It cannot be practically used for electrodes or resistance heating elements.

Example 4 The polymer of Reference Example 2 was manufactured into a sheet having a thickness of 1.5 mm and a width of 20 cm by a T-molding machine having a diameter of 30 mm and manufactured by Thermoplastics.

To this sheet (10 cm x 10 cm), electrolytic copper foil (35 μm thick) manufactured by Mitsui Mining & Smelting Co., Ltd. was stuck on both sides and fused at 260 ° C by a press molding machine. The dielectric constant and dielectric loss of the double-sided copper clad plate are 2.2 and 4.5 × 10 ^-4 , respectively, and the peel strength is 1.0 kg /
It was in cm. This copper clad plate was coated with a photoresist (Fuji Synthetic Chemical Research Laboratory No. 200), and a fine pattern was formed with an alkaline developer and an etching treatment (ferric chloride saturated solution). As a result, a fine pattern of 100 μ or less could be formed.

Example 5 Maleic anhydride was graft-copolymerized with the polymer of Reference Example 2 to obtain a modified product having a maleic anhydride content of 1.5 wt%. This polymer was mixed with the polymer of Reference Example 2 in an amount of 10 wt% and molded into a sheet to fuse a double-sided copper foil. The permittivity of double-sided copper clad board
2.3, the dielectric loss tangent was 6.5 × 10 ^-4 . The peel strength is
It was 1.6 kg / cm.

Example 6 The polymer of Reference Example 6 was dissolved in cyclohexane, impregnated in a glass cloth for printed boards, and dried. Stack 6 sheets of polymer-impregnated glass cloth, press-press at 260 ℃,
A highly rigid body having a thickness of 1.5 mm and a Young's modulus of 8 × 10 ¹⁰ dyne / cm ² was obtained. Thereafter, the modified product described in Example 5 was coated on its back surface with a copper foil having a thickness of 10 μm to both sides of the laminate. as a result,
The double-sided copper clad plate had a dielectric constant of 2.8, a dielectric loss tangent of 5.8 × 10 ^-4 and a peel strength of 1.1 kg / cm.

Claims (4)

[Claims] 1. Tetracyclododecene or its derivative: 5
0-100 mol% and norbornene or its derivatives: 0-
A conductive composite characterized in that a conductive organic film or a metal film is provided on the surface of a stretched or unstretched sheet or film of a polymer obtained by hydrogenating a ring-opening polymer consisting of 50 mol%. material. 2. A conductive film having a light transmittance of 50% or more and 10 or more.
The conductive composite material according to claim 1, which has a specific resistance of 0 Ωcm or less. 3. The conductive composite material according to claim 1, which is used as a transparent conductive film. 4. The conductive composite material according to claim 1, which is used as a high-frequency circuit board.