JP2002133944A - Conductive ink composition, method for printing very fine pattern using the same, and manufacturing method of translucent electromagnetic shield member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive ink composition capable of always forming excellent printing patterns continuously, a method for printing very fine pattern, and a manufacturing method of a translucent electromagnetic shielding member using the same by which the excellent translucent electromagnetic shielding member having a stable quality is continuously manufactured in a simple manner and at low cost. SOLUTION: The conductive ink composition satisfies the expression (1) of 4<=η1/η2<=12 (1), where η1 and η2 are the viscosity of the ink composition measured by a cone plate type rotational viscometer under the same conditions except printing speed in a measurement, η1 is the viscosity at a printing speed of 1 sec-1, and η2 is the viscosity at a printing speed of 12 sec-1. The printing method is used in the intaglio offset printing of the conductive ink composition. In the manufacturing method of the translucent electromagnetic shield member, the electromagnetic shield pattern is formed by laminating a metal layer on the very fine printing pattern formed by the printing method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel conductive ink composition particularly suitable for printing a fine pattern by an intaglio offset printing method, a fine pattern printing method using this composition, and The present invention relates to a method for manufacturing a transparent electromagnetic wave shield member using a fine pattern formed by a printing method.

[0002]

2. Description of the Related Art In recent years, various reports have been made on the effects of electromagnetic waves emitted from electronic devices on the human body. Along with this, for example, CRTs (cathode ray tubes), PDs, etc.
There is increasing interest in technology for effectively shielding electromagnetic waves emitted from a display screen such as a P (plasma display panel). In order to shield an electromagnetic wave emitted from a normal electric device or the like, a method of making the case metal or attaching a metal plate to the case is performed.

However, in order to shield the electromagnetic waves emitted from the display screen of the CRT or PDP, not only the electromagnetic wave shielding effect is excellent, but also the visibility of the display on the display screen is not hindered. Since it is also required to have excellent light transmissivity (translucency), the metal plate cannot be used as it is. Therefore, for the purpose of shielding electromagnetic waves emitted from a display screen such as a CRT without impairing the visibility of the display, for example,
(1) A mesh made of fibers mixed with a highly conductive metal filament, (2) a transparent substrate having fibers of a conductive material such as stainless steel or tungsten embedded therein
No. 35284, JP-A-5-269912, and JP-A-5-327274), (3) A transparent substrate having a metal or metal oxide vapor deposition film formed on the surface (JP-A 1-2).
78800, JP-A-5-323101) and the like are used.

However, the use of the mesh (1) among the above causes a problem that the display screen becomes dark and the contrast and resolution are lowered. In addition, since the transparent member of (2) has fibers embedded inside, the manufacturing method is complicated and the cost is high, and the display screen is also dark, and there is a problem that contrast and resolution are deteriorated. .. Further, in the case of (3), if the vapor deposition film is thinned to the extent that sufficient translucency can be maintained, the surface resistance of the film is reduced and the attenuation property of electromagnetic waves is reduced. There is a problem that the shield effect cannot be achieved at the same time.

As a member for covering a display screen of a CRT or the like to shield electromagnetic waves, for example, in addition to the above examples, for example, an ink prepared by mixing a highly conductive metal powder on the surface of a transparent substrate is grid-shaped by a screen printing method. Formed by printing in a striped or striped pattern (JP-A-62-57297, JP-A-9-283977) and a mesh pattern made of conductive ink, which is formed by screen printing. Those baked in vacuum
No. 52499), or an ink in which a metal powder is mixed with an ultraviolet curable epoxy acrylate resin, the printing method is unknown, but the surface of a transparent substrate is printed and formed in a grid pattern and then cured by irradiating with ultraviolet rays. (Tokuhei 2-4
However, even if these members are used, a sufficient electromagnetic wave shielding effect and translucency cannot be achieved at the same time.

That is, in order to achieve both excellent electromagnetic wave shielding effect and translucency, it is necessary to optimize the pattern line width and the pattern gap (pitch) and further reduce the electric resistance of the pattern. It is considered that such a viewpoint is not considered in any of the techniques described in each of the above-mentioned publications, and that the method for creating a pattern is also insufficiently considered. For example, in order to obtain sufficient translucency, it is preferable that the line width of the pattern be extremely thin and the interval be large, but in this case, the shield effect becomes insufficient. Further, it is difficult to form a pattern having an extremely narrow line width of several tens of μm or less by the screen printing method, and there arises a problem that the line width of the pattern varies or a number of places where the pattern is interrupted occur. ..

In the embodiment disclosed in Japanese Patent Publication No. 2-48159, the pattern line width is 100 μm.
Since it is m, it is estimated that printing is performed by a conventional method such as a screen printing method, and it is several tens of μ.
It is difficult to form a pattern having an extremely thin line width of m or less, and there are problems that the line width of the pattern varies as described above, or that a number of places where the pattern is interrupted occur.

On the other hand, in order to enhance the shielding effect, it is preferable to reduce the electric resistance of the pattern as much as possible. However, when a general conductive paste composed of metal powder and resin is used as the ink, its specific resistance is sufficient. Although extremely small, when an extremely thin pattern is formed, the electric resistance between the patterns becomes very high, and it becomes difficult to sufficiently enhance the shielding effect. Further, the pattern formed by the conductive paste has a metallic luster, and there is a problem that the contrast of the display screen is deteriorated by reflection of external light or internal light emission.

Therefore, in order to suppress the decrease in contrast, conductive carbon black is used in combination with the metal powder,
Although it is conceivable to make the printed pattern black, carbon black has a higher resistance value than metal powder, and therefore when used together there is a problem that the conductivity of the printed pattern becomes low and the electromagnetic wave shielding property deteriorates. In addition, in particular for PDP applications, severe electromagnetic wave shielding performance is required, and it is expected that the demand will become more severe in the future. Patterns can be formed only with the above-mentioned conductive paste mainly composed of metal powder or carbon black. There is also a problem that the formed shield member is becoming unable to obtain sufficient shield performance to meet this requirement.

Japanese Unexamined Patent Publication (Kokai) No. 3-35284 describes that a thin metal film is formed on the surface of a transparent plastic substrate by vapor deposition or the like, and then patterned by a chemical etching process.
Japanese Patent Publication No. 2 discloses that a geometric pattern made of a metal thin film is provided on the surface of a transparent substrate also by a chemical etching process. Also, in the same manner, JP-A-10-163
Japanese Patent No. 673 describes that a transparent resin coating film containing a plating catalyst is formed on the surface of a transparent substrate, a metal thin film such as copper is formed on the transparent resin coating film by electroless plating, and then patterning is also performed by a chemical etching process. There is.

According to these methods, a very fine pattern can be formed with high precision, and the severe electromagnetic wave shielding performance required especially for PDP applications can be achieved. However, in the chemical etching process, it is necessary to use the photolithography method to form such a fine pattern, and the manufacturing cost is extremely high, which is disadvantageous in terms of cost. In particular, in order to deal with a large screen such as a PDP, the exposure apparatus and the etching apparatus must be upsized, and the manufacturing equipment becomes very expensive.

Further, most of the metal thin film once formed on the surface of the transparent substrate needs to be removed, which is wasteful.
There is also a problem that it takes time, labor and cost to treat the waste liquid after etching.

[0013]

Therefore, the present inventors firstly transferred the ink image formed on the surface of the intaglio plate to the surface of the transfer body, and then printed from the surface of the transfer body to the surface of the printing medium. After printing a fine print pattern made of a conductive ink composition and having a line width of 5 to 40 μm on the surface of a transparent substrate as a printing object by a printing method,
It was studied to selectively laminate and form a metal layer on this printed pattern by electroplating or electroless plating to manufacture a translucent electromagnetic wave shield member.

According to this method, as described above, the line width is 5 to 5.
By adopting the intaglio offset printing method, a fine print pattern of 40 μm, which cannot be printed by the screen printing method, can be formed easily and at low cost as compared with the chemical etching process. Therefore, it is possible to easily and inexpensively manufacture a light-transmitting electromagnetic wave shield member that is excellent in both light-transmitting property and electromagnetic wave shielding effect and has no fear of lowering contrast.

However, after that, the inventors further studied to put the above method into practical use and actually produce a transparent electromagnetic wave shield member. As a result, the same intaglio and the same intaglio were obtained by the intaglio offset printing method. It has been clarified that the following problems occur in the process of continuously printing a print pattern on a large number of transparent substrates using a transfer body. (a) In the initial stage of printing, the desired fine print pattern having a line width of 5 to 40 μm can be satisfactorily printed, but as the number of printed sheets passes, the conductive ink composition, mainly from the intaglio plate to the transfer body, is printed. As a result, the transferability of
Alternatively, there are many places where the pattern is interrupted and comes off. That is, the shape of the print pattern easily changes during continuous printing, and the continuous printing characteristics are poor.

(B) Although there is almost no change in the shape of the print pattern due to continuous printing, bleeding easily occurs from the initial stage of printing, and only a print pattern thicker than the intended line width can be obtained. That is, the initial printing characteristics are poor. According to the study by the inventors, all of these problems occur remarkably in printing that requires a uniform and fine print pattern over the entire surface of a large area, such as a transparent electromagnetic wave shield member. However, when the cause was pursued, it became clear that it was mainly due to the physical properties of the conductive ink composition.

A main object of the present invention is to provide a novel conductive ink composition capable of continuously forming a good printing pattern without causing the above-mentioned printing defects. Another object of the present invention is to provide a novel method for printing a fine pattern, which can always form a good print pattern continuously by using the above conductive ink composition.

Still another object of the present invention is to use the above-mentioned printing method, which is excellent in both translucency and shielding effect of electromagnetic waves, and which is free from the possibility of lowering the contrast and is of good quality. Another object of the present invention is to provide a novel method of manufacturing a transparent electromagnetic wave shield member capable of continuously manufacturing a stable transparent electromagnetic wave shield member of (3) easily and at low cost.

[0019]

Means for Solving the Problems and Effects of the Invention In order to solve the above problems, the inventors examined the physical properties of the conductive ink composition. As a result, a so-called cone-plate type rotary viscometer having a flat plate and a cone-shaped cone having an apex with an obtuse angle formed perpendicularly to the plate surface and in point contact is used. The ratio of the viscosity of the ink measured by η ₁ /η ₂ [wherein η ₁ and η ₂ are ink compositions measured by a cone-plate type rotational viscometer under the same conditions except for the shear rate at the time of measurement] Viscosity of η ₁ offset speed 1se
The viscosity at c ⁻¹ and the viscosity at η ₂ offset speed of 12 sec ⁻¹ . ] Has a great influence on the printing characteristics of the conductive ink composition during continuous printing.

That is, the conductive ink composition has the above ratio η
_The smaller ₁ /η ₂ is, the smaller the decrease in transferability from the intaglio plate to the transfer body is, and the better the continuous printing characteristics are.
Bleeding is more likely to occur and the initial printing characteristics deteriorate, and conversely the ratio η ₁
As /η ₂ is larger, bleeding is less likely to occur and the initial printing characteristics are improved, but the transferability from the intaglio plate to the transfer body is greatly deteriorated and continuous printing characteristics are deteriorated. Therefore, the inventors have formed a conductive ink composition which has a good balance between both continuous printing characteristics and initial printing characteristics and is capable of good printing with excellent characteristics, and has a ratio range of η ₁ /η ₂ . As a result of further examination of the above, the present invention has been completed.

Therefore, the conductive ink composition of the present invention is an ink composition to which conductivity is imparted by blending a conductive powder, and the formula (1): 4≦η ₁ /η ₂ ≦12 (1) [wherein eta _1, eta ₂ are each other than a shear rate during the measurement under the same conditions, a viscosity of the measured ink composition by a cone plate type rotational viscometer, eta ₁ is a shear rate 1se
The viscosity at c ⁻¹ and the viscosity at η ₂ offset speed of 12 sec ⁻¹ . ] Is satisfied.

The fine pattern printing method of the present invention is an intaglio offset printing method in which an ink image formed on the surface of an intaglio plate is transferred to the surface of a transfer body, and then the surface of the transfer body is printed on the surface of a printing material. Is a printing method for printing a fine pattern having a line width of 5 to 40 μm, which is made of a conductive ink composition, on the surface of an object to be printed by adding conductive powder as a conductive ink composition. It is characterized by using the above-mentioned one satisfying the above formula (1).

According to the conductive ink composition of the present invention and the method for printing a fine pattern, both the continuous printing characteristics and the initial printing characteristics are balanced as described above, and excellent characteristics are obtained. Because you can print
It is possible to continuously form a fine print pattern having a line width of 5 to 40 μm while always maintaining a good state. The method for producing a translucent electromagnetic wave shield member of the present invention is a method for producing a translucent electromagnetic wave shield member having an electromagnetic wave shield pattern that transmits visible light and does not transmit electromagnetic waves, wherein By the method of printing the pattern, on the surface of the transparent substrate as the printed material,
A conductive ink composition having a line width of 5 to 40 μm and a formula (2): 1≦Sk/Ss≦9 (2) [wherein Ss is a region where a print pattern is printed on the surface of the transparent substrate. The total surface area Sk is the total surface area of the unprinted area. ] Forming a print pattern consisting of a stripe pattern, a grid pattern or a geometric pattern that satisfies the above, and then selectively laminating and forming a metal layer on the print pattern to form an electromagnetic wave shield pattern. Is characterized by.

According to the manufacturing method of the present invention, a metal is formed on a fine printed pattern having a line width of 5 to 40 μm which is continuously formed by the fine pattern printing method while always maintaining a good state. Since the electromagnetic wave shield pattern can be formed by stacking and forming layers, the light-transmitting electromagnetic wave shield member is excellent in both the light-transmitting property and the electromagnetic wave shielding effect and is not likely to deteriorate the contrast, and is stable in quality. Can be continuously manufactured simply and at low cost.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below. <Conductive ink composition> The conductive ink composition of the present invention is an ink composition to which conductivity is imparted by blending the conductive powder as described above, and has the formula (1): 4≦η ₁ / η ₂ ≦12 (1) [wherein η ₁ and η ₂ are the viscosities of the ink compositions measured by a cone-plate type rotational viscometer under the same conditions except for the shear rate at the time of measurement, _{1 off} speed 1se
The viscosity at c ⁻¹ and the viscosity at η ₂ offset speed of 12 sec ⁻¹ . ] Must be satisfied.

If the ratio η ₁ /η ₂ is less than 4, as described above, the deterioration of the transferability from the intaglio plate to the transfer member is small and the continuous printing characteristics are good, but the bleeding is likely to occur and the initial printing characteristics are deteriorated. Getting worse. On the other hand, when the ratio η ₁ /η ₂ exceeds 12, bleeding is less likely to occur and the initial printing characteristics are improved, but the transferability from the intaglio plate to the transfer body is greatly deteriorated and continuous printing characteristics are deteriorated. Note that the ratio η ₁ /η ₂ is in the range of about 5 to 11.5, especially within the above range, considering that the continuous printing characteristics and the initial printing characteristics are balanced to perform good printing with excellent characteristics. Preferably.

The viscosities η ₁ and η ₂ are, as shown in FIG. 1, a flat plate P and an apex C1 having an obtuse apex angle (180°-2θ) formed perpendicular to the surface P1 of the plate P. In addition, a so-called cone-plate type rotational viscometer having a cone-shaped cone C arranged so as to make point contact is used, and the ink I as a sample is injected into the gap between the cone C and the plate P. Cone C as shown by the arrow
Can be obtained by measuring the torque applied to the plate P when the ink I is sheared by rotating at a constant speed.

The measurement condition is that the shear rate is 1 s as described above.
ec ^-1 (for viscosity η ₁ ) and 12 sec ^-1 (for viscosity η ₂
In the case of), the conditions are exactly the same except that it is changed to. The specific numerical value is not particularly limited, but in the examples and comparative examples described later, the measurement temperature is 23±1° C. and the relative humidity is 65±.
The measurement was performed under the condition of 5%. As in the prior art, the conductive ink composition of the present invention preferably contains a solvent-soluble resin, a solvent capable of dissolving the resin, and a conductive powder.

Among these, as the conductive powder, metal powder is particularly preferably used, and as the metal powder, for example, silver,
Examples include copper, iron, nickel, aluminum and gold. Each metal powder can be used alone, or 2
It is also possible to use two or more kinds in combination. Further, it may be a plated composite (for example, silver-plated copper) or an alloy. Among these metal powders, silver, nickel, or copper powder is preferably used in consideration of conductivity, cost, and oxidation resistance, that is, the property that an oxide having high insulating property is hard to be generated.

In particular, a combination system of silver powder having an average particle size of 1 to 10 μm and nickel powder having an average particle size of 0.1 to 1 μm is preferable. In such a combination system, silver powder [Ag] and nickel powder [Ni] are used. And the weight ratio [Ag]/[Ni] is 1
By blending in a ratio of /8 to 8/1, the viscosity ratio η ₁ /η ₂ is adjusted to the range of 4 to 12 described above. That is, when the amount of silver powder is larger than the above ratio, the ratio η ₁ /
η ₂ may fall below 4, and conversely, when the amount of nickel powder is large, the ratio η ₁ /η ₂ may exceed 12.

The weight ratio [Ag]/[Ni] is more preferably 1/1 to 6/2 even within the above range. The higher the packing density of the metal powder in the conductive ink composition is, the more preferable it is from the viewpoint of increasing the conductivity of the printed pattern and further favorably forming the metal layer by electroplating. Further, the conductivity of the printed pattern is not only determined by the volume resistivity of the metal powder itself used, but is greatly influenced by the contact resistance between the metal powders in the pattern. For example, even if the inside of the print pattern is densely filled with metal particles, if the contact resistance between the metal powders is large, the conductivity of the entire print pattern will be low.

Therefore, as the metal powder, scale-like ones are preferably used in consideration of increasing the contact surface between the metal powders, rather than spherical or millet-like ones. It does not exclude things. The amount of the conductive powder such as the metal powder added to the conductive ink composition is 400 to 120 with respect to 100 parts by weight of the total amount of the resin.
The amount is preferably about 0 parts by weight, more preferably about 700 to 1000 parts by weight. In the above-mentioned combination system of silver powder and nickel powder, the total amount of both is regulated within this range.

If the amount of the conductive powder added is less than the above range, the electroconductivity of the printed pattern is lowered. Therefore, in the production of the translucent electromagnetic wave shield member, the surface of the printed pattern is not electroplated and/or non-exposed. Electrolytic plating makes it difficult to stack and form a metal layer having excellent conductivity, and it may not be possible to form an electromagnetic wave shielding pattern having an excellent electromagnetic wave shielding effect. On the contrary, when the amount of the conductive powder added exceeds this range, the binding force of the resin as the binder that binds the conductive powders to each other is weakened, so that the conductivity of the printing pattern is also reduced. It is not easy to laminate and form a metal layer having excellent conductivity on the surface by electroplating and/or electroless plating, and it may not be possible to form an electromagnetic wave shielding pattern having an excellent electromagnetic wave shielding effect.

The resin that forms the conductive ink composition together with the above-mentioned conductive powder includes thermosetting, ultraviolet curable,
Alternatively, various resins such as thermoplastic resins can be used, but thermosetting or ultraviolet curable resins are preferably used in consideration of heat resistance and weather resistance of the printed pattern. Examples of the thermosetting resin include various resins such as polyester-melamine, melamine, epoxy-melamine, phenol, polyimide, thermosetting acrylic, and polyurethane. Examples of the ultraviolet curable resin include various resins such as polyester, polyvinyl butyral, acryl, phenol and polyurethane.

When the former thermosetting resin is used and the curing temperature cannot be increased due to, for example, the heat resistance of the material to be printed, paratoluenesulfonic acid or paratoluenesulfonic acid blocked with amine, Alternatively, a curing catalyst such as blocked isocyanate may be added. The solvent is added to dissolve the resin and adjust the viscosity of the conductive ink composition containing the resin and the conductive powder to a range suitable for intaglio offset printing. For example, various conventionally known solvents having a boiling point of 150° C. or higher are preferably used. This is because when the boiling point of the solvent is lower than 150° C., the ink composition is likely to be dried during printing and the ink composition is likely to change over time.

Specific examples of such a solvent include alcohols [hexanol, octanol, nonanol,
Decanol, undecanol, dodecanol, tridecanol, tetradecanol, ventadecanol, stearyl alcohol, ceryl alcohol, cyclohexanol, terpineol, etc.] and alkyl ethers [ethylene glycol monobutyl ether (butyl cellosolve), ethylene glycol monophenyl ether, diethylene glycol, Diethylene glycol monobutyl ether (butyl carbitol), cellosolve acetate, butyl cellosolve acetate, carbitol acetate, butyl carbitol acetate, etc.], and one or more of them may be used in consideration of printability and workability. It is selected as appropriate.

When a higher alcohol is used as a solvent, the drying property and fluidity of the ink composition may be deteriorated. Therefore, butyl carbitol, butyl cellosolve, ethyl carbitol, and butyl cellosolve acetate, which have better drying properties than these, may be used. , Butyl carbitol acetate, etc. may be used together. The solvent has a viscosity of the conductive ink composition of about 50 to 2000 poise (P), particularly 100 to
It is preferable to adjust the addition amount so that the amount becomes about 1000P.

When the viscosity of the conductive ink composition is lower than this range or is higher than this range, the printability of the conductive ink composition is deteriorated in either case,
This is because it is possible that a fine pattern cannot be formed. The viscosity here is the viscosity η ₂ measured at the shear rate of 12 sec ⁻¹ , which was measured by the cone-plate type rotational viscometer. The conductive ink composition is prepared by blending the above-mentioned components, thoroughly stirring and mixing, and then kneading.

<Fine Pattern Printing Method> In the fine pattern printing method of the present invention, the ink image formed on the surface of the intaglio plate is transferred to the surface of the transfer body, and then the surface of the transfer body is printed on the surface of the printing object. By the intaglio offset printing method, on the surface of the substrate to be printed, consisting of a conductive ink composition,
A method for printing a fine pattern having a line width of 5 to 40 μm, characterized by using the composition of the present invention described above as the conductive ink composition.

The intaglio plate used in the above printing method has a flat plate shape in which a predetermined concave portion corresponding to the printing pattern is formed on the surface of the substrate, a flat plate shape wound in a cylindrical shape, or a cylindrical shape. Examples include a thing or a cylindrical thing. The smoothness of the surface of the substrate is important. If the smoothness is poor, when the ink composition is filled in the recesses of the intaglio plate with a doctor blade, ink will remain on the surface of the intaglio plate other than the recesses, and stains on the non-image areas (ground stains). Occurs.

The degree of smoothness is not particularly limited, but it is preferably about 1 μm or less, more preferably about 0.5 μm or less, expressed by the ten-point average roughness Rz. Examples of such a substrate include glass substrates such as soda lime glass, non-alkali glass, quartz glass, low alkali glass, and low expansion glass, as well as fluororesin, polycarbonate (PC), polyether sulfone (PES), Resin plates such as polyester and polymethacrylic resin, and metal substrates such as stainless steel, copper, nickel and low expansion alloy amber can be used. Among them, it is preferable to use a glass plate that can produce the intaglio plate having a good surface smoothness at the lowest cost and can form the edge shape of the pattern very sharply.

However, since non-alkali glass used for printing original plates for photolithography in the field of LSI and the like is very expensive, soda lime glass is required as long as the accuracy is about the printing pattern of the transparent electromagnetic wave shielding member. Is enough. The concave portion of the intaglio plate is formed by a photolithography method, an etching method, an electroforming method, or the like. The depth of the concave portion is appropriately set according to the thickness of the target print pattern,
You can set it, but the ink remaining in the recess (usually,
About half the amount of the ink remains in the recess),
Or considering the reduction of the thickness after printing due to evaporation of the solvent, it is about 1 to 50 μm, especially 3 to 20 μm.
It is preferably about the same.

The transfer body used in the intaglio offset printing together with the intaglio printing plate is not particularly limited as long as its surface has excellent ink releasability, but the surface energy as an index showing the ink releasability is not limited. Value is 15 to 30d
The transfer material is preferably about yn/cm, particularly about 18 to 25 dyn/cm. Examples of such a transfer material include various materials in which at least the surface layer is formed of silicone rubber, fluororesin, fluororubber, or a mixture thereof. Among them, silicone rubber has excellent ink releasability, It is preferably used because almost 100% of the ink transferred from the can be transferred onto the printing material.

Examples of the silicone rubber include various silicone rubbers such as heat curing type (HTV) and room temperature curing type (RTV). Particularly, room temperature curing type addition type silicone rubber produces a by-product during curing. Since it does not occur at all and has excellent dimensional accuracy, it is preferably used. The hardness of the surface layer of the transfer body formed of the above silicone rubber or the like is determined according to Japanese Industrial Standard JISK in consideration of printing accuracy and the like.
6301 spring type hardness (JIS A)
Is about 20 to 70°, preferably about 30 to 60°.

That is, in the case of a hard transfer member having a surface layer hardness exceeding this range, the ink in the recesses is transferred because the surface layer is not sufficiently pressed into the recesses when pressed against the intaglio printing plate in intaglio offset printing. There is a possibility that the transfer may not be sufficiently transferred to the surface of the body and accurate printing may not be performed. Conversely, a soft transfer member whose surface layer has a hardness less than this range is
In the intaglio offset printing, when the intaglio plate or the object to be printed is pressed into contact with the plate, the deformation of the surface layer becomes large, so that it may be impossible to perform accurate printing.

The surface of the transfer member is preferably smooth in consideration of printing accuracy and the like, and it is preferable that the unevenness of the surface does not affect the printing. Specifically, it is represented by ten-point average roughness. It is preferably 0.0 μm or less, and particularly preferably 0.5 μm or less. The transfer body has a blanket (sheet) shape (used by wrapping it around a cylindrical body),
A roller-shaped member or a curved elastic member used for pad printing or the like may be used as long as it does not cause print misalignment.

According to the fine pattern printing method of the present invention, as described above, a fine print pattern having a line width of 5 to 40 μm can be continuously formed in a good condition. Therefore, as described below, by selectively laminating and forming a metal layer on the printed pattern to form an electromagnetic wave shield pattern, it is possible to manufacture a good transparent electromagnetic wave shield member with stable quality. It will be possible. Further, the conductive ink composition of the present invention and the method for printing a fine pattern using the same are also suitable for manufacturing a printed wiring board.

That is, the ink composition of the present invention is used on the insulating substrate and the line width is 5 to 40 by the printing method of the present invention.
A printed wiring board is manufactured by forming a fine print pattern of μm, and optionally laminating and forming a metal layer on the formed print pattern in the same manner as above to form a conductor circuit. To be done. The printed wiring board thus obtained can improve the circuit density by narrowing the line width and the line interval as compared with the conventional one in which a conductor circuit or a printed pattern which is its origin is formed by a screen printing method.
This makes it possible to perform the manufacturing more easily and at a lower cost than that in which a conductor circuit is formed using patterning by a chemical etching process.

Moreover, since the initial printing characteristics and the continuous printing characteristics at the time of forming the printing pattern are well balanced, according to the present invention, the printed wiring board having the excellent characteristics as described above is maintained with these characteristics. However, it becomes possible to manufacture continuously. <Manufacturing Method of Translucent Electromagnetic Wave Shield Member> The manufacturing method of the translucent electromagnetic wave shield member of the present invention comprises a conductive ink composition on the surface of a transparent substrate as a material to be printed by the method of printing a fine pattern described above. After forming a print pattern consisting of a striped pattern, a grid pattern, or a geometric pattern made of an object, a step of selectively laminating and forming a metal layer on the print pattern to form an electromagnetic wave shield pattern is included. It is a feature.

As the transparent substrate, any glass or film having sufficient transparency to visible light can be used, but a resin film or sheet which can be continuously processed in a roll form is preferable. Examples of the resin forming the film or sheet include polyesters typified by polyethylene terephthalate (PET), polyolefins such as polyethylene and polypropylene, halogen-containing resins such as polyvinyl chloride and polyvinylidene chloride,
Styrene-based resins such as polystyrene, polyether sulfone, polycarbonate, polyamide, polyimide,
Acrylic resins and the like can be mentioned. Among them, particularly, the light-transmitting property is good, the cost is low, and the flexibility is excellent. Moreover, even after the conductive ink composition is printed, a heat treatment or an ultraviolet irradiation treatment is performed. PET having heat resistance that does not deform is most preferably used.

The thickness of the transparent substrate is not particularly limited, but from the viewpoint of maintaining the light-transmitting property of the electromagnetic wave shield member, the thinner it is, the more preferable it is. Usually, the form in use (film form, sheet form) or required. The thickness is appropriately set in the range of 0.05 to 5 mm depending on the mechanical strength. As described above, the print pattern formed by printing on the surface of the transparent substrate has a line width of 5 to 40 μm and formula (2): 1≦Sk/Ss≦9 (2) [where Ss is a transparent substrate] Shows the total surface area of the area where the print pattern is printed, and Sk shows the total surface area of the non-printed area. ] Must be satisfied. The reason is as follows.

Among the inventors, Kondo was first in the line width 5 to 80 μm.
It has been found that a stripe pattern having a line spacing of m and a line interval of 200 to 3000 μm has a capability of sufficiently cutting an electric field component at a frequency of 1 to 500 MHz. However, as a result of further study by the inventors, the electromagnetic wave shielding performance is insufficient in this line width range, particularly in the region where the frequency exceeds 500 MHz, and the severe electromagnetic wave shielding performance required for the PDP application described above, specifically, Frequency of 0.1 MH
It has become clear that the performance of sufficiently cutting the electric field component at z to 1 GHz may not be achieved in some cases.

Therefore, the inventors prepared a striped model pattern having a laminated structure of a printed pattern made of the conductive ink composition and a metal layer described later,
From the equivalent circuit, the line width of the printed pattern and the aperture ratio [proportion of the area not printed, Formula (3): aperture ratio (%)=Sk/(Sk+Ss)×100 (3) can be obtained. ] And the electromagnetic wave shielding performance were examined.

As a result, it has been clarified that the thinner the line width is, the better the electromagnetic wave shielding performance is at the same aperture ratio. That is, in order to improve the electromagnetic wave shielding performance without deteriorating the translucency defined by the aperture ratio and to achieve the severe electromagnetic wave shielding performance required for the above PDP application, a large number of patterns having a line width as small as possible are formed. After examining the specific range,
It was found that the line width should be 40 μm or less.

Further, when the lower limit of the line width is examined, it is also found that if the line width is less than 5 μm, disconnection is likely to occur when forming a print pattern, and a good product cannot be stably produced. However, it was revealed from these results that the line width of the printed pattern needs to be within the range of 5 to 40 μm. Further, as the aperture ratio is higher, the transmittance of visible light, which is an index of translucency, is improved, but on the contrary, the electromagnetic wave shielding property is deteriorated. Therefore, considering the trade-off, the aperture ratio is within the range of 50 to 90%. It also turned out to have to be.

Therefore, based on the range of the aperture ratio and the range of the line width, the total surface area Ss of the printed area and the total surface area S of the non-printed area on the surface of the transparent substrate.
When the ratio Sk/Ss to k is calculated, 1 to
It became clear that it was necessary to be within the range of 9. In order to achieve the severe electromagnetic wave shielding performance required for PDP applications, the aperture ratio is particularly preferably 60 to 80% within the above range, and the aperture ratio range and the line width (=5 ˜40 μm), the above ratio Sk/
When a more preferable range of Ss was determined, it was also found to be about 2 to 7.

As the shape of the print pattern, for example, in addition to the above-mentioned stripe shape shown in FIGS. 2A and 3, the grid shape shown in FIGS. 4 to 6 is preferably adopted. Of these, in the striped print pattern 10, for example, as shown in FIG. 3, the line width Ws of each ink layer 10a forming the print pattern 10 and the area between the ink layers 10a in which the transparent substrate 2 is exposed. By adjusting the width Wk and the number of ink layers 10a, the ratio Sk/Ss is regulated within the above range.

Similarly, in the grid-shaped print pattern 10 shown in FIGS. 4 and 5, the line width Ws of the ink layers 10b and 10c in the vertical direction and the horizontal direction as shown in the respective figures.
₁ and Ws ₂ and the width W of the region where the transparent substrate 2 is exposed between the ink layers 10b and 10c in each of the above _two directions.
k ₁ , Wk ₂ , and ink layers 10b, 10c in both directions
The ratio Sk/Ss is defined in the above range by adjusting the number of lines and the number of lines.

FIG. 6 shows a printing pattern 10 in the form of a square grid, in which the ink layers 10 in the vertical and horizontal directions are formed.
bs and 10c have the same line width Ws ₁ and Ws ₂ (Ws ₁ =Ws ₂ )
And the widths Wk ₁ and Wk _{2 of} the areas where the transparent substrate 2 is exposed between the ink layers 10b and 10c are the same (Wk ₁ =Wk ₂ ). W
By adjusting s ₁ and Ws ₂ , the widths Wk ₁ and Wk _{2 of the} regions, and the number of ink layers 10b and 10c in both directions, the ratio Sk/Ss is defined within the above range.

At this time, in each drawing, each ink layer 10
It goes without saying that the line widths Ws, Ws ₁ and Ws _{2 of} a, 10b and 10c are limited to the ranges of 5 to 40 μm described above. It is also important to pay attention to the line width and the like so that moire fringes (interference fringes) do not occur in the image in relation to the dot pitch of the display screen. Examples of print patterns other than the above include geometric patterns such as a circular pattern shown in FIG. 7A, a diamond pattern shown in FIG. 7B, and a regular hexagonal pattern shown in FIG. 7C.

In each of the above figures, reference numeral 10a is each ink layer constituting the print pattern 10, and reference numeral 2 is the ink layer 1.
Showing the transparent substrate exposed between 0a is similar to the example in each of the previous figures. In the circular print pattern 10 of FIG. 7A, assuming that the circle is replaced with a square having the same area, the width of the print pattern portion provided between adjacent squares is defined as the line width. ..

Other numerical values that define the size and shape of the print pattern 10 are not particularly limited, but the thickness of the ink layers 10a, 10b, 10c forming the print pattern 10 is free from disconnection as described above. , An accurate printing pattern 10 faithful to the original plate is obtained, and electroplating is performed using the printing pattern 10 as a cathode, and then,
In order to stack and form the metal layer 11 described below with an accurate pattern that is also faithful to the original plate, approximately 0.5
It is preferably about 50 μm, more preferably about 1 to 30 μm. <Metal Layer> In the present invention, as shown in FIG. 2( b ), on the ink layer 10 a that constitutes each of the printing patterns 10,
As shown in FIG. 2A, the electromagnetic wave shield pattern 1 is formed by selectively laminating and forming the metal layer 11 by electroplating using the printed pattern 10 as a cathode and/or electroless plating. Such a translucent electromagnetic wave shield member is completed.

As the metal forming the metal layer 11, any of various metals having excellent conductivity and capable of electroplating or various metals capable of electroless plating can be used. Examples of metals are silver, copper, iron,
At least one selected from the group consisting of nickel, aluminum and gold can be used, and silver or copper is preferably used in terms of conductivity and cost. Further, the surface of the metal layer 11 may be blackened, and black nickel plating or the like may be applied to the outermost surface layer of the metal layer 11 in order to prevent deterioration of the contrast of the display screen mainly due to reflection of internal light emission.

The thickness of the metal layer 11 is preferably 0.5 μm or more in consideration of obtaining a good electromagnetic wave shielding effect. The upper limit of the film thickness of the metal layer 11 is not particularly limited, but even if the film thickness exceeds 50 μm, not only a further electromagnetic wave shielding effect cannot be obtained, but also the plating step requires a long time to produce the film. There is a risk of problems in terms of efficiency and cost. Therefore metal layer 1
Within the above range, the film thickness of 1 is preferably 50 μm or less, and more preferably about 1 to 30 μm.

The metal layer may be a single layer or multiple layers, and in the case of multiple layers, it may have a laminated structure of a layer formed by electroless plating and a layer formed by electroplating.

[0066]

[Ester of trimellitic anhydride and neopentyl glycol (weight average molecular weight: 20,000), manufactured by Sumitomo Rubber Industries, Ltd.]

Melamine resin 20-Curing catalyst Para-toluenesulfonic acid 1-Solvent Butyl carbitol acetate 40 Examples 2 and 3 The same as Example 1 except that the amounts of silver powder and nickel powder were changed to the values shown in Table 1 below. Thus, the conductive ink compositions of Examples 2 and 3 were produced.

Comparative Example 1 A conductive ink composition of Comparative Example 1 was prepared in the same manner as in Example 1 except that the nickel powder was not mixed and the silver powder was mixed in an amount of 900 parts by weight. Comparative Example 2 A conductive ink composition of Comparative Example 2 was produced in the same manner as in Example 1 except that the silver powder was not blended and the nickel powder was blended in an amount of 800 parts by weight.

Viscosity Measurement by Cone Plate Type Rotational Viscometer The viscosities η ₁ and η ₂ of the conductive ink compositions prepared in the above Examples and Comparative Examples were measured using a cone plate type rotational viscometer (model number MR101) manufactured by Rheology Co. It was used and measured under the following conditions, and the ratio η ₁ /η ₂ was determined from the results. <Measurement conditions> Measurement temperature: apex angle of 23 ± 1 ° C. (adjusted by connecting the plate P in a constant temperature water bath) Cone C vertex C1 (180 ° -2θ): 170 ° diameter: 20 mm, shear rate: 1 sec ^{- 1} or 12 sec ^-1 Evaluation of Printing Characteristics <Printing Step> The conductive ink compositions prepared in Examples and Comparative Examples were used to prepare a transparent substrate by an intaglio offset printing method using the following intaglio and a silicone blanket as a transfer body. After printing on the surface of a transparent PET film with a thickness of 0.1 mm as
The ink layer 10 was heated and cured at 0° C. for 1 hour to form a square grid pattern shown in FIG. 6 corresponding to the intaglio pattern.
b, 10c thickness 10 μm, line width Ws ₁ =Ws ₂ =20 μ
m, line spacing Wk ₁ =Wk ₂ =100 μm, Sk/Ss=
Printed pattern 10 was 2.27. (Intaglio plate) A substrate made of soda lime glass, in which recesses (depth=10 μm) corresponding to the above-described predetermined pattern are formed by etching. (Silicone blanket) A layer (additional-type RTV silicone rubber layer having a spring hardness (JIS A) of 40° (10-point average surface roughness of 0.3 μm) is formed on the outermost layer.

<Initial printing characteristics> The first PET film on which a printing pattern was formed in the above printing step was visually observed and evaluated according to the following criteria. (Evaluation Criteria) O: No ink bleeding or squeeze-out was observed, and the initial printing characteristics were extremely good.

Δ: The ink slightly oozes and spills out, but there is no problem in practical use and the initial printing characteristics were good. Poor: Ink bleeding and squeezing out were considerable, and line thickening was partially observed, and initial printing characteristics were poor. <Continuous printing characteristics> 20 printing steps are performed continuously,
All the PET films on which the print patterns were formed were visually observed, and the transition of the print state from the first sheet (initial) was evaluated according to the following criteria.

(Evaluation Criteria) A: Up to the 20th sheet, the printing state did not change from the first sheet, and the continuous printing characteristics were good. Δ: Density unevenness occurred in a part of the print pattern during the continuous printing. The continuous printing characteristics were somewhat poor. X: A dropout occurred in part of the print pattern during the continuous printing. The continuous printing characteristics were poor.

The above results are shown in Table 1.

[0073]

[Table 1]

From the table, when the conductive ink composition of Comparative Example 1 having a viscosity ratio η ₁ /η ₂ of less than 4 was used, the continuous printing characteristics were good, but the initial printing characteristics were poor.
On the other hand, when the conductive ink composition of Comparative Example 2 in which the viscosity ratio η ₁ /η ₂ exceeds 12 was used, conversely, although the initial printing characteristics were good, the continuous printing characteristics were found to be poor. .. On the other hand, when the conductive ink compositions of Examples 1 to 3 in which the viscosity ratio η ₁ /η ₂ is within the range of 4 to 12, the initial printing characteristics and the continuous printing characteristics are well balanced. It was confirmed that good printing can be continuously performed.
In particular, when the conductive ink compositions of Examples 2 and 3 in which the viscosity ratio η ₁ /η ₂ is in the range of ₅ to 11.5 are used, both initial printing characteristics and continuous printing characteristics are particularly excellent. It was possible to print.

Production of Translucent Electromagnetic Wave Shield Member A print pattern was formed using the conductive ink compositions of Examples and Comparative Examples in the printing step, the first and 20th sheets.
Using the first PET film, the following steps
A transparent electromagnetic wave shield member was manufactured. <Layer formation of metal layer> The PET film is dipped in a copper sulfate plating solution, and the printed pattern formed on the surface thereof is used as a cathode to apply an electric current of ² A/dm ² to perform electrolytic copper plating to perform the printing. 5μ thick selectively on the pattern
A copper coating layer of m was formed to produce a transparent electromagnetic wave shield member having an electromagnetic wave shield pattern (total thickness 15 μm) patterned in the above-mentioned square lattice pattern shown in FIG.

Evaluation of Translucent Electromagnetic Wave Shield Member The above-mentioned translucent electromagnetic wave shield member was subjected to the following tests to evaluate its characteristics. Electromagnetic wave shield effect test About a sample produced by cutting a translucent electromagnetic wave shield member into a length of 20 cm and a width of 20 cm, and sandwiching it in a closed cell, a frequency of 0.1 MHz to 1 GHz according to the KEC method established by the Kansai Electronics Industry Promotion Center. The attenuation factor (dB) of the electromagnetic wave in the range was measured to evaluate the electromagnetic wave shielding effect of each sample in the above frequency range.

In the table which will be described later, as an index of the shield effect, the attenuation rate (dB) of electromagnetic waves at a frequency of 1 GHz.
The following shows the results of evaluation by the following evaluation criteria. (Evaluation Criteria) XX: 0 to 20 dB X: 20 to 40 dB Δ: 40 to 60 dB ◯: 60 to 70 dB ⊚: 70 dB translucency test Visible light (wavelength 4) in the translucent electromagnetic wave shield member.
Spectral transmittance of 100 to 700 nm) was measured. Then, using the lowest value as an index, the translucency of each translucent electromagnetic wave shield member was evaluated according to the following evaluation criteria.

(Evaluation Criteria) XX: 0 to 50% X: 50 to 60% Δ: 60 to 70% ◯: 70 to 80% ⊚: over 80% Visibility test After adhering to the display screen of the PDP panel via the acrylic transparent adhesive with the pattern inside, the visibility of the display image was evaluated according to the following criteria.

(Evaluation Criteria) x: Unevenness and mesh were observed over the entire surface. Δ: Slight unevenness and mesh were observed. ◯: No unevenness or mesh was observed. Also, the contrast was sufficiently high, and a good image was obtained. ⊚: No unevenness or mesh was observed, and the contrast was extremely high, and an extremely good image was obtained.

The results are shown in Table 2.

[0081]

[Table 2]

From the table, it was found that the light-transmitting electromagnetic wave shield member having the printed pattern formed using the conductive ink composition of Comparative Example 1 had a slightly insufficient visibility on the first printed sheet. In addition, the transparent electromagnetic wave shield member in which a printed pattern was formed using the conductive ink composition of Comparative Example 2 showed a tendency that the electromagnetic wave shield effect was slightly lower than that of the first printed sheet, and the visibility of the 20th printed sheet was high. Was confirmed to have deteriorated.

On the other hand, all of the transparent electromagnetic wave shielding members having a printed pattern formed by using the conductive ink compositions of Examples 1 to 3 have excellent electromagnetic wave shielding effect on the first and 20th sheets, respectively. In addition, it was confirmed that it has excellent translucency and visibility.

[Brief description of drawings]

FIG. 1 is a diagram for measuring the viscosity of a conductive ink composition,
It is a figure which shows the outline of a cone-plate type rotational viscometer.

2A and 2B are views showing an example of a translucent electromagnetic wave shield member manufactured according to the present invention, wherein FIG. 2A is a perspective view showing the whole, and FIG. 2B is a perspective view of FIG. 2A. It is a -B line expanded sectional view.

FIG. 3 is a plan view showing a stripe-shaped pattern as an example of a printed pattern in a transparent electromagnetic wave shield member.

FIG. 4 is a plan view showing a grid pattern as another example of a print pattern.

FIG. 5 is a plan view showing another grid-like pattern as still another example of the print pattern.

FIG. 6 is a plan view showing still another grid pattern as another example of the print pattern.

FIG. 7 is a plan view showing a geometric pattern as still another example of a print pattern, in which FIG. 7A is a circular pattern, FIG. 7B is a rhombic pattern, and FIG. (c)
Is a regular hexagonal pattern.

[Explanation of symbols]

1 Electromagnetic wave shield pattern 10 Printing pattern 11 Metal layer 2 Transparent substrate

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H05K 9/00 H05K 9/00 VF term (reference) 2H113 AA01 AA04 AA06 BA03 BB07 BB09 BC12 CA17 CA31 CA42 EA06 EA08 EA10 EA12 FA06 4J039 AD07 AD09 AE02 AE03 AE04 AE05 AE06 AE09 BA06 BA32 BA38 BC07 BC12 BC14 BC15 BC79 CA07 EA03 EA04 EA24 EA42 EA48 GA03 5E321 AA04 BB23 DA25 DA05 DA05 DA05 DA05 DA05 DA05 DA05 DA05 DA05 DA05 DA05 DA05 DA05 DA03 DA03 DA03 DA04 DA04 DA05

Claims (8)

[Claims] 1. An ink composition to which conductivity is imparted by blending a conductive powder, the formula (1): 4≦η ₁ /η ₂ ≦12 (1) [wherein η ₁ and η ₂ are each other shear rate during the measurement under the same conditions, a viscosity of the measured ink composition by a cone plate type rotational viscometer, eta ₁ is a shear rate 1se
The viscosity at c ⁻¹ and the viscosity at η ₂ offset speed of 12 sec ⁻¹ . ] The conductive ink composition characterized by satisfying these. 2. A solvent-soluble resin, a solvent capable of dissolving the resin, and a conductive powder.
The conductive ink composition described. 3. A conductive powder having an average particle size of 1 to 10 μm.
Silver powder [Ag] and nickel powder [Ni] having an average particle size of 0.1 to 1 μm in a weight ratio [Ag]/[Ni] of 1/
The conductive ink composition according to claim 2, wherein the ratio is 8 to 8/1 and the total amount of both is 400 to 1200 parts by weight with respect to 100 parts by weight of the total amount of the resin. 4. An intaglio offset printing method in which an ink image formed on the surface of an intaglio plate is transferred to the surface of a transfer body, and then the surface of the transfer body is printed on the surface of the printing object by an intaglio offset printing method. Line width 5-40 consisting of ink composition
A printing method for printing a fine pattern of μm, wherein conductivity is imparted by blending conductive powder as a conductive ink composition, formula (1): 4≦η ₁ /η ₂ ≦12 (1) [wherein eta _1, eta ₂ are each other than a shear rate during the measurement under the same conditions, a viscosity of the measured ink composition by a cone plate type rotational viscometer, eta ₁ is a shear rate 1se
The viscosity at c ⁻¹ and the viscosity at η ₂ offset speed of 12 sec ⁻¹ . ] A method of printing a fine pattern, characterized by using a material satisfying the following. 5. The method of printing a fine pattern according to claim 4, wherein a surface of the transfer body which is in direct contact with the conductive ink is formed of silicone rubber. 6. The surface roughness (10-point average roughness) Rz of the surface of the transfer member which is in direct contact with the conductive ink is 0.5 μm.
The method for printing a fine pattern according to claim 4, wherein the following is used. 7. A method for producing a translucent electromagnetic wave shield member having an electromagnetic wave shield pattern which transmits visible light but does not transmit electromagnetic waves, which is used as a material to be printed by the method for printing a fine pattern according to claim 4. On the surface of the transparent substrate of the conductive ink composition, line width 5 ~ 40μ
m and the formula (2): 1≦Sk/Ss≦9 (2) [where Ss is the total surface area of the region where the print pattern is printed on the surface of the transparent substrate, and Sk is the total of the unprinted region. Indicates the surface area. ] Forming a print pattern consisting of a stripe pattern, a grid pattern or a geometric pattern that satisfies the above, and then selectively laminating and forming a metal layer on the print pattern to form an electromagnetic wave shield pattern. A method for manufacturing a translucent electromagnetic wave shield member, comprising: 8. The method for producing a translucent electromagnetic wave shield member according to claim 7, wherein a metal layer is laminated and formed on the printed pattern by at least one of electroplating and electroless plating.