JP2005063843A - Printing method of electrode pattern for plasma display panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printing method of high printing accuracy and high productivity in printing an electrode for a plasma display panel by an intaglio offset system. <P>SOLUTION: With the use of a printing blanket with silicone rubber as a surface rubber layer, an electrode pattern consisting of electrode-forming ink made of either conductive metal ink or black ink is printed on a base plate. At that time, printing is made so that a relation between a transfer speed V (mm/sec) and a viscosity η<SB>10</SB>(Pa s) at a shearing speed of 10 sec<SP>-1</SP>in a process of transferring the electrode-forming ink from an intaglio to the printing blanket satisfy a formula (1): (6-0.02×V)≤η<SB>10</SB>≤(30-0.01×V) [where 0<V<300]. A thixotropy value of the ink η<SB>1</SB>/η<SB>10</SB>is preferably 3≤η<SB>1</SB>/η<SB>10</SB>≤10. By this, the printing accuracy is well maintained and an efficient transfer speed can be selected easily. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method of printing an electrode pattern by intaglio offset printing when manufacturing an electrode for a plasma display panel.

  The plasma display panel (PDP) is self-luminous, can reduce power consumption, is thin and easy to enlarge, and has a simpler structure than a liquid crystal display (LCD). As a next-generation display device, great demand is expected. However, under the present circumstances, the manufacturing cost of PDP is extremely high, which is a major obstacle to popularization as a display device for home use.

  For example, as shown in FIG. 1, the PDP includes a front plate (front substrate) 10 including a bus electrode (front electrode) 11, a transparent electrode 12, a transparent dielectric layer 13, and a protective layer 14 on a transparent substrate 15, and address electrodes. (Back electrode) 21, dielectric layer 22, protective layer 23, rib 24 and back plate (rear substrate) 20 including fluorescent layers 25 (R, G, B), electrodes 11 provided on both substrates, 12 and 21 are arranged so as to face each other through the fluorescent layer 25.

  Conventionally, the bus electrode pattern has a predetermined thickness by applying a black photosensitive paste to the entire surface of the front plate, and further applying a photosensitive silver paste (for example, “DuPont” product name “Fordel®”). It has been mainly formed by photolithography, which comprises adjusting (5 to 10 μm) and drying and then exposing and developing the pattern according to the shape of the pattern.

  In this case, the bus electrode pattern usually has a line width of several tens of μm and a pitch of about several hundreds of μm. Therefore, most of the black paste and silver paste applied to the entire surface of the front plate are exposed. -Washing and removal are performed after the development processing, and the pattern forming material is wasted. In addition, since it is necessary to repeat the processes such as coating, exposure, and development in each of the black photosensitive paste and the photosensitive silver paste, a large cost is required for manufacturing the bus electrode. Furthermore, although both the photosensitive black paste and the silver paste are expensive and a process for recovering only silver from the discarded silver paste has been proposed, there is a problem that the cost for recovery is extremely high. .

  In addition, the manufacturing equipment used for pattern formation by the photolithography method requires extremely high precision and cleanliness, which increases costs and makes it difficult to cope with an increase in the size (screen size) of PDPs. There is a problem that there is. In addition, since a large amount of harmful waste liquid is generated during the development process, there is a problem in that the waste liquid is expensive to process.

  In recent years, it has been proposed to form an electrode pattern of a PDP by offset printing, and if a precise pattern can be formed by this printing method, it is freed from problems of high cost and waste liquid treatment when using a photolithography method. . For offset printing of a PDP electrode pattern, a transparent substrate such as a glass substrate is used as a printed body, and an electrode in which an inorganic powder component such as a conductive metal powder or a black metal powder is mixed with an organic component such as a resin or an organic solvent. Since printing is performed using the forming ink, it is important to appropriately set ink properties and printing conditions during offset printing in order to print a precise pattern.

Conventionally, regarding offset printing of AC type plasma display or the like, Patent Document 1 includes filling a groove of an intaglio with a phosphor ink composed of a vehicle containing a depolymerized organic binder, a phosphor powder, and a white pigment, A printing method is disclosed in which a transfer speed and a printing speed are set to 20 to 100 mm / sec when a phosphor layer is printed on a substrate after being transferred to a silicone rubber blanket.
JP-A-8-176479 (Claims 1, 6, 9, [0053])

  If the PDP electrode pattern using conductive metal ink or black ink can be industrially advantageously implemented by the intaglio offset printing method, as described above, the manufacturing cost reduction and the waste liquid treatment problem can be solved. Conventionally, it has been known that when an intaglio offset printing is performed using a silicone material having good ink releasability as a blanket, the ink film thickness and the printing shape are improved. On the other hand, silicone rubber has a problem in terms of ink acceptability. Increasing the transfer speed when transferring ink from an intaglio to a silicone blanket results in more pinholes and wire breakage in the printed material, and finally from the intaglio. In some cases, the ink cannot be transferred to the blanket and printing cannot be continued. Therefore, the problem is how to increase the printing speed and increase the productivity by setting a high transition speed.

  Accordingly, an object of the present invention is to enable the setting of conditions for increasing the printing speed by increasing the ink transfer speed from the intaglio to the blanket when printing the electrode pattern for PDP by intaglio offset printing using a silicone blanket. The present invention is intended to improve the productivity of manufacturing electrodes for PDP.

In order to solve the above-mentioned problems, the present inventors have reached the present invention as a result of various studies on the relationship between the viscosity of the PDP electrode pattern forming ink and the ink transferability. That is, the present invention is the following PDP electrode pattern printing method.

1) When forming an electrode pattern for a plasma display panel on a substrate by intaglio offset printing using a printing blanket with silicone rubber as a surface rubber layer, using an electrode forming ink made of conductive metal ink or black ink, A step of transferring the electrode forming ink from the intaglio to a printing blanket, and a step of transferring the ink from the blanket to the substrate. A transfer rate V (mm / sec) in the transfer step and a shear rate of the ink of 10 sec. The relationship with the viscosity η ₁₀ (Pa · s) at ⁻¹ is represented by the formula (1):
(6-0.02 × V) ≦ η ₁₀ ≦ (30−0.1 × V) (1)
[However, 0 <V <300, and η ₁₀ is the viscosity (Pa · s) of the ink measured by a parallel plate viscometer. The electrode pattern for a plasma display panel is printed so as to satisfy the above requirements.

  2) The surface rubber layer of the blanket has a hardness represented by JIS-A of 20 to 80 °, and a surface roughness represented by ten-point average roughness (Rz) of 0.01 to 3.0 μm. The method for printing an electrode pattern for a plasma display panel as described in the above item 1), wherein the printing method comprises a silicone rubber.

  3) The electrode for forming a plasma display panel according to 1) above, wherein the electrode forming ink is a black ink containing at least a conductive metal powder, a black metal powder, a glass frit and an organic component capable of being removed by baking. Electrode pattern printing method.

  4) The electrode pattern for a plasma display panel according to 1) above, wherein the electrode forming ink is a conductive metal ink containing at least a conductive metal powder, glass frit, and an organic component capable of being removed by baking. Printing method.

  5) The method for printing an electrode pattern for a plasma display panel as described in 3) or 4) above, wherein the conductive metal powder is silver powder.

  The PDP electrode pattern printing method of the present invention is applied to pattern formation of bus electrodes or address electrodes as illustrated in FIG. The bus electrode is formed by laminating and printing the black ink referred to in 2) and the conductive metal ink referred to in 3).

  The PDP electrode pattern printing method of the present invention is characterized in that it is carried out so as to satisfy the relationship of the formula (1). In other words, when the transition speed V (mm / sec) is in the range of 0 <V <300, the fast transition speed can be selected with high printing accuracy if the relationship of the formula (1) is satisfied. it can. That is, the optimum viscosity range varies depending on the transfer speed, and the range of ink viscosity that can be selected becomes narrower when the transfer speed is increased. If the ink viscosity is lower than the range specified by Formula (1), the printed shape of the electrode pattern is greatly deteriorated, the straight line performance is lost, or the ink is piled on the blanket and transferred to the 100% substrate. Cause problems. On the other hand, if the viscosity range specified by the formula (1) is exceeded, the ink transfer from the intaglio plate becomes worse and pinholes are likely to occur. If it is within the range specified by the formula (1), it is possible to print in a good state without generating pinholes or disconnection.

  In intaglio offset printing of the electrode pattern for PDP, by printing the relationship between the viscosity of the electrode forming ink and the ink transfer speed from the intaglio to the silicone blanket so as to satisfy the relationship of the above formula (1), Accurate printing can be performed. Further, since the transfer speed as fast as possible can be easily selected while maintaining good printing accuracy, it is possible to find printing conditions with good productivity. Therefore, the manufacturing cost can be reduced as compared with the conventional photolithography method, and the problem of waste liquid treatment can be solved.

In the printing method of the present invention, the relationship represented by the formula (1) is shown in FIG. In this figure, the range hatched enclosed by line segments represented by segment and (formula) η ₁₀ = 6-0.02V represented by formula () η ₁₀ = 30-0.1V Intaglio offset printing is performed by selecting the relationship between η and V as shown.

Furthermore, the electrode forming ink has a viscosity in the range of the above formula (1) and a thixo value of the formula (2)
3 ≦ η ₁ / η ₁₀ ≦ 10 (2)
(In the formula, η ₁ / η ₁₀ means a thixo value, and η ₁ and η ₁₀ are the same conditions except for the shear rate at the time of measurement, and the viscosity (Pa · s) of the ink measured with a parallel plate viscometer. ), Where η ₁ represents the viscosity at a shear rate of 1 sec ⁻¹ and η ₁₀ represents the viscosity at a shear rate of 1 sec ^-10 .) The printed shape is further improved.

  In the present invention, a printing blanket in which the surface rubber layer is silicone rubber is used. The silicone rubber has a hardness (JIS A hardness) of 20 to 80 ° and a surface roughness (ten-point average roughness Rz). Is preferably from 0.01 to 3 μm. The thickness is usually selected from the range of 1 to 1500 μm.

In the present invention, the viscosities η ₁ and η ₁₀ were measured with a parallel plate viscometer. That is, while rotating the upper plate with the object (electrode forming ink) sandwiched between two parallel plate cones of φ20 mm, the torque was measured from the torque meter installed on the rotating shaft of the upper plate cone, and the rotation speed was changed. Η ₁ and η ₁₀ were calculated from the torque at the time. The measurement conditions are exactly the same except that the shear rate is changed to 1 sec ⁻¹ (for η ₁ ) and ₁₀ sec ⁻¹ (for η ₁₀ ) as described above. Although the specific numerical value is not specifically limited, In the Example and comparative example which are mentioned later, it measured on the conditions of measurement temperature 23 degreeC and relative humidity 55%.

  The printing method of the present invention can be applied to intaglio offset printing of electrode patterns in the formation of bus electrodes (front electrodes) 11 and address electrodes (back electrodes) 21 on the front plate (front substrate) 10 shown in FIG. .

[Ink for pattern printing]
The PDP electrode pattern forming ink contains a component for exhibiting a desired function such as conductivity and blackness imparting, and is prepared such that its viscosity η ₁₀ is in the range of the formula (1). For example, if the transition speed V (mm / sec) is set to 100 mm / sec, the ink viscosity η _{10 at} that time is 4 (Pa · s) ≦ η ₁₀ ≦ 20 (Pa · s) according to the equation (1). It is prepared to be in the range of s). On the contrary, for ink prepared with a certain viscosity in advance, offset printing is performed by selecting the transition speed V so as to satisfy the relationship of the formula (1). In this case, if a transition speed V as fast as possible is selected from the range satisfying the expression (1), the printing speed is increased and the productivity is improved. For example, when preparing an ink having the desired function, the types and blending ratios of the components are limited. Therefore, if the viscosity range is also limited, the printing accuracy is well secured within those limitations. In this state, the fastest transition rate can be easily determined.

  In the above formula (1), the transition speed V is on condition that 0 <V <300. However, in consideration of the printing model and the like, it is preferable that the transition speed V is actually in the range of 50 <V <300. .

Further, it is preferable that the ink has a thixo value η ₁ / η _{10 in the} range represented by the above formula (2), thereby ensuring more reliable ink transfer from the intaglio to the blanket, and printing accuracy. Can be kept higher.

  The ink for forming an electrode pattern used in the present invention includes a conductive metal powder, a black metal powder, a glass frit and a black ink containing at least an organic component that can be removed by baking, a conductive metal powder, a glass frit, and a material that can be removed by baking. A conductive metal ink containing at least an organic component is a target. The black ink and the conductive metal ink are inks for printing the black electrode and the bus main electrode constituting the front electrode in the electrode for PDP, respectively, and are prepared by mixing and dispersing the above components. .

  As the conductive metal powder, various conductive metal powders conventionally used for forming bus electrodes can be used. In order to make the bus electrode more excellent in conductivity, silver, copper, It is preferable to use at least one metal powder selected from the group consisting of gold, platinum, aluminum, nickel, iron and palladium. Of these, silver powder is more preferably used.

  The particle size of the conductive metal powder is preferably in the range of 0.05 to 20 μm, more preferably in the range of 0.1 to 5.0 μm. When the particle diameter exceeds 20 μm, the degree of flattening of the surface of the conductive metal powder deposit is reduced, and the flatness of the bus electrode may be lowered. Conversely, if the particle size is less than 0.05 μm, the conductivity of the finally obtained bus electrode may be reduced. Generally, by reducing the particle size of the conductive metal powder, it is possible to lower the melting temperature between metals, simplify the process, and further improve the conductivity significantly. it can.

The glass frit is conventionally used, for example, a softening temperature is 400 to 600 ° C., an expansion coefficient _α300 is 70 × 10 ^{−7 to} 95 × 10 ⁻⁷ / ° C., and a glass transition temperature is 400 to 500 ° C. Some can be used. Examples thereof include Bi ₂ O ₃ / SiO ₂ / B ₂ O ₃ glass, Bi ₂ O ₃ / ZnO / B ₂ O ₃ glass, PbO / SiO ₂ / B ₂ O ₃ glass, ZnO / B _2. Examples include O ₃ alkaline earth metal oxide glass. The average particle size of the glass frit is preferably in the range of 0.1 to 5 μm.

  As the resin, various resins such as a thermosetting type, an ultraviolet curable type, and a thermoplastic type can be used. Examples of the thermosetting resin include polyester-melamine resin, melamine resin, epoxy-melamine resin, phenol resin, polyimide resin, and acrylic resin. Examples of the ultraviolet curable resin include acrylic resins. Examples of the thermoplastic resin include polyester resin, polyvinyl butyral resin, cellulose resin (such as ethyl cellulose), and acrylic resin.

In the present invention, among these resins, in particular, polyvinyl butyral resin, cellulose resin (especially ethyl cellulose), acrylic, which decomposes completely into CO ₂ and H ₂ O by firing (for example, by firing at a high temperature of 400 ° C. or higher). It is preferable to use a resin or the like. These resins can be used alone or in a suitable mixture of two or more according to the printability.

  The solvent is selected in consideration of the printability of the ink. When used for intaglio offset printing, the ink solvent directly contacts the surface rubber layer of the printing blanket, causing the surface rubber layer to swell and change its surface wetting characteristics. In general, if the solvent is small enough to swell the surface rubber layer, even if printing is repeated, the surface wettability of the printing blanket changes little and stable printing can be performed. Conversely, if the degree of swelling of the surface rubber layer is large, the surface wettability changes greatly by repeating printing, the line width of the pattern to be printed widens, and even fine stains on the surface of the printing plate The transfer stability and the transfer efficiency from the printing blanket to the substrate to be printed are reduced, resulting in a significant decrease in printing stability. Therefore, it is preferable that the degree of swelling is small, but considering the acceptability of the ink from the printing intaglio to the printing blanket, it is preferable that a certain degree of swelling occurs.

  The solvent has a volume increase rate (swelling rate) of 20% or less, preferably 10% or less when the silicone rubber constituting the surface printing layer of the printing blanket is immersed at room temperature (23 ° C.) for 24 hours. Some are preferred.

  Other requirements for the solvent are not limited to this, but for example, the boiling point is preferably 150 ° C. or higher. When the boiling point of the solvent is lower than 150 ° C., it becomes easy to dry on a glass substrate or the like at the time of printing, and the printing characteristics may be changed. Moreover, there is a possibility that the conductive ink composition is likely to change with time. Specific examples of such solvents include alcohols (hexanol, octanol, nonanol, decanol, undecanol, dodecanol, tridecanol, tetradecanol, bentadecanol, stearyl alcohol, seryl 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, strong lupitol acetate, butyl carbitol acetate, etc. 1 type or 2 types or more are appropriately selected in consideration of printability and workability.

  When a higher alcohol is used as a solvent, the drying property and fluidity of the ink composition may be reduced. Therefore, butylcarbitol, butylcellosolve, ethylcarbitol, butylcellosolve acetate, Tall acetate or the like may be used in combination.

  In the present invention, the blending ratio of each component in the conductive metal ink is required to contain 90 to 99% by weight of conductive metal powder and 1 to 10% by weight of glass frit after firing, It is determined so as to satisfy the relationship of the formula (1), and more preferably to satisfy the formula (2). For example, 100 parts by weight of resin, 500 to 2500 parts by weight of conductive metal powder, and 10 to 150 parts by weight of glass frit, and the solvent satisfies the above formula (1), and preferably the above formula (2). It can be prepared by changing its kind and blending amount. The ink is produced by mixing and dispersing these blends using, for example, a three roll.

  The black ink used to print and form the black electrode is a mixture of conductive metal powder, black metal powder, glass frit, and a compound containing organic components such as resin and solvent that can be removed by firing. Those prepared by dispersing are used. Here, the conductive metal powder, glass frit, and organic components (resin, solvent, etc.) can all be the same as the conductive metal ink.

The black metal powder may be any metal that is black at room temperature and does not change color even when baked at a temperature of 500 to 700 ° C. for 5 to 60 minutes, and does not decompose or sublime. Examples thereof include oxide and black composite alloy powders. Examples of the black metal oxide include ruthenium oxide (RuO ₂ ), manganese oxide (MnO), molybdenum oxide (MoO ₂ ), chromium oxide (Cr ₂ O ₃ ), copper oxide (CuO), titanium oxide (TiO), Examples thereof include one or more metal oxides selected from the group consisting of palladium oxide (PdO) and iron oxide (Fe ₂ O ₃ ). Examples of the black composite alloy include Cr—Co—Mn—Fe, Cr—Cu, Cr—Cu—Mn, Mn—Fe—Cu, Cr—Co—Fe, Co—Mn—Fe, and Co—Ni—. The 1 type (s) or 2 or more types selected from the group which consists of Cr-Fe and Cu-Fe-Cr can be mentioned. These black metal oxides and black composite alloys are added as powder having a particle size of about 0.05 to 20 μm.

  The composition ratio of the black ink is, after firing, for example, containing 1 to 25% by weight of conductive metal powder, 30 to 94% by weight of black metal powder, and 5 to 45% by weight of glass frit, It is determined so as to satisfy the relationship of the formula (1), and more preferably to satisfy the formula (2). It is determined so as to satisfy the printability and the above oxo value. For example, 100 parts by weight of resin, 10 to 1000 parts by weight of conductive metal powder, 200 to 2500 parts by weight of black metal powder, and 100 to 1500 parts by weight of glass frit, where the solvent is the formula (1), Preferably, it can be prepared by changing the kind and blending ratio so as to satisfy the above formula (2). A black ink can be produced by mixing and dispersing these blends using, for example, three rolls.

  In addition to the above components, a black pigment may be appropriately used in combination with the black ink on condition that the relationship of the formula (1) and more preferably the relationship of the formula (2) is satisfied. Examples of the black pigment include carbon black, titanium black, graphite, and other black pigments or dyes. Considering the printability of black ink, the particle diameter of the black metal oxide, composite alloy, and black pigment powder is preferably 0.05 to 20 μm.

  In addition, in the conductive metal ink and the black ink, on the condition that the relationship of the above formula (1), more preferably the above formula (2) is satisfied, pattern casting prevention at the time of firing other inorganic components, It can be added according to a known method for the purpose of controlling the reflectance and dielectric constant. Examples of other inorganic components include boron oxide, silica, zirconium oxide, magnesium oxide, calcium oxide, barium oxide, tin oxide, indium tin oxide, silicate, steatite, zircon, forsterite, and beryllia. These inorganic components can be made into a powder having an average particle size of 0.05 to 20 μm and contained in a range of 100 to 500 parts by weight with respect to 100 parts by weight of the glass frit.

[Printing method of ink pattern]
In printing the electrode pattern according to the present invention, in order to perform continuous printing with high accuracy, it is preferable to provide a step of heating and drying the surface of the blanket and a step of cooling after transferring the ink pattern from the blanket to the transparent substrate.

  That is, when the silicone rubber layer absorbs the solvent in the ink during printing and swells, it leads to a decrease in printing accuracy, but the solvent of the surface rubber layer is evaporated and dried by heating and drying as described above. The state can be returned to the state before swelling with the solvent of the ink. The transpiration of the solvent and the ease of drying vary depending on the heating temperature, the boiling point of the solvent of the ink, the thickness of the surface rubber layer, etc. However, it is usually effective if the heating temperature is 40 to 200 ° C. Transpiration and drying can be achieved. The method of heating and drying is not particularly limited, and may be indirectly heated through a blanket cylinder, and by blowing hot air of 80 to 120 ° C. from the outside to the surface rubber layer for about 5 to 30 seconds. You may heat directly.

  After the heating and drying process, the surface temperature of the printing blanket is high. If printing is performed in this state, the surface rubber layer and the printing plate in contact with the surface will thermally expand. The accuracy may be reduced. Therefore, for example, cool air should be applied to the surface of the printing blanket so that the change in the surface temperature of the printing plate is within ± 1 ° C and the change in the surface temperature of the printing blanket (surface rubber layer) is within ± 5 ° C. It is preferable to perform a cooling process such as spraying, contacting the surface of the printing blanket with a member having a large heat capacity such as metal, or dissipating heat through the blanket cylinder. For example, it may be cooled by blowing cold air of 10 to 15 ° C. for about 0.3 to 2 minutes.

  In the printing method of the present invention, an intaglio offset printing method is applied among conventionally known printing methods. Other printing methods, for example, screen printing methods, have a problem that when the line width of the pattern is less than 100 μm, it is impossible to faithfully reproduce the shape of the pattern, or disconnection occurs. There is also a problem that it is difficult to form. Further, in principle, the force applied to the central portion and the peripheral portion of the screen is different, and the amount of elongation is different, resulting in different pattern printing accuracy on the same back substrate. Therefore, the printing accuracy required for the bus electrode [error within ± 20 μm, preferably within ± 10 μm, more preferably within ± 10 μm within an area of a 40 inch substrate (900 mm × 600 mm)] is sufficiently satisfied. Can not.

  Also, the direct printing method and the offset printing method produce a protruding portion of ink called a marginal zone around the pattern, so the resolution of the printing plate itself is low and it is extremely difficult to reproduce the pattern faithfully. is there. In addition, in the case of intaglio direct printing (gravure printing), uniform printing pressure is applied to a glass substrate that is rigid and has uneven thickness due to the fact that the plate used for direct printing is a rigid member. There is a problem that transfer unevenness is likely to occur.

  In contrast to these printing methods, the intaglio offset printing method can freely control the film thickness of the pattern by changing the depth of the concave portion of the intaglio. In addition, by using a printing blanket with a surface rubber layer made of a material with low surface energy such as silicone rubber, the ink transferred from the printing plate (intaglio) to the printing blanket can be applied to rigid substrates. It is possible to transfer 100%.

  Since the cost required to form the pattern by the intaglio offset printing method is about 1/3 to 1/10 that of the photolithography method, the bus electrode of the front plate for PDP should be formed at a very low cost. Can do.

[Print blanket]
As for the printing blanket used when the ink pattern is formed by the intaglio offset printing method, for the purpose of forming the ink pattern with high accuracy, as described above, the printing blanket in which the surface rubber layer is made of silicone rubber. Is used. The silicone rubber preferably has a hardness (JIS A hardness) of 20 to 80 ° and a surface roughness (10-point average roughness Rz) of 0.01 to 3 μm.

  When the hardness of the surface rubber layer exceeds the above range, deformation of the surface rubber layer is difficult to occur during printing, and the acceptability of ink on the printing plate may be reduced. On the other hand, if the hardness of the surface rubber layer is below the above range, the degree of deformation of the surface rubber layer at the time of printing becomes large, which may cause a decrease in printing accuracy. The hardness of the surface rubber layer is particularly preferably in the range of 20 to 70 °, more preferably in the range of 30 to 60 °, in the above range (JIS A hardness).

  The surface roughness of the surface rubber layer has a greater influence on the printed shape as the pattern to be printed is finer. When forming the bus electrode of the front plate for PDP, the line width required for the ink pattern is about several tens μm, more specifically about 20 μm. Therefore, the surface roughness of the surface rubber layer is the ink pattern. From the viewpoint of improving the printing shape of the ink, it is required that the 10-point average roughness (Rz) is 0.01 to 3 μm.

  If the 10-point average roughness (Rz) of the surface rubber layer exceeds the above range, the printed shape may be deteriorated, for example, the edge shape of the pattern may not be sharp. On the other hand, it is difficult to reduce the 10-point average roughness (Rz) of the surface rubber layer to be less than the above range, and the acceptability of the ink may be lowered if the surface roughness is extremely small. is there. The 10-point average roughness (Rz) of the surface rubber layer is more preferably 0.01 to 0.5 μm in the above range.

  The thickness of the surface rubber layer is set according to the degree of deformation during printing, and is usually set in the range of 1 to 1500 μm. When the thickness of the surface rubber layer is less than 1 μm, the surface rubber layer is hardly deformed during printing, and the ink acceptability of the printing plate may be lowered. On the other hand, if the thickness of the surface rubber layer exceeds 1500 μm, the degree of deformation of the surface rubber layer at the time of printing increases, which may cause a decrease in printing accuracy.

[Printing Intaglio]
As the intaglio, one having a high surface smoothness is used. If the surface smoothness is poor, when the ink is doctored, ink remains on the surface of the intaglio plate and stains (background stains) occur on the non-image area. An intaglio with good smoothness is obtained, for example, by etching a glass substrate, and is inexpensive. As the glass, either soda lime glass or non-alkali glass can be used, but when high dimensional accuracy is required, it is preferable to use non-alkali glass although it is expensive. The depth of the intaglio is designed according to the target ink film thickness, but is usually about 1 to 50 μm. According to the present invention, almost 100% of the ink filled in the intaglio can be transferred onto the silicone blanket. As the intaglio pattern, a pattern corresponding to a desired front electrode pattern for a plasma display panel is used.

〔substrate〕
The transparent substrate used as the front plate in the PDP electrode is not particularly limited except that it has high transparency and heat resistance. For example, soda lime glass, low alkali glass, non-alkali glass, quartz glass, etc. A glass substrate is preferably used. The material of the transparent substrate is appropriately selected from the glass substrates and the like exemplified above according to various characteristics such as heat resistance, chemical resistance, and permeability.

[Baking of ink pattern]
After the PDP electrode pattern is printed and formed by the intaglio offset printing method of the present invention, a PDP electrode is manufactured by subjecting it to a firing step. The conditions for firing the ink pattern are the same as conventional methods: the type of resin used for conductive metal ink and black ink (thermal decomposition temperature), the type of conductive metal powder, the type of glass frit (melting point), etc. However, from the viewpoint of improving the conductivity of the bus electrode, it is usually preferable to set the firing temperature in the range of 500 to 700 ° C.

  When the firing temperature of the ink pattern is in the above range, organic components such as resin in the ink pattern can be almost completely thermally decomposed, and the conductive metal powder, black inorganic oxide, and glass frit are melt-bonded. A bus electrode having a two-layer structure is produced. Therefore, the conductivity of the bus electrode can be made excellent while maintaining the blackness of the bus electrode surface on the entire surface of the front plate. The firing temperature of the ink pattern may be a temperature at which the resin of the ink is decomposed to melt the conductive metal powder.

[Other members, etc.]
In the production of the front plate for PDP, the black ink and the conductive metal powder for forming the bus electrode and the transparent substrate serving as the base of the bus electrode are as described above, but other members (for example, transparent electrode, The transparent dielectric layer, protective layer, etc.), its material, formation method and the like are not particularly limited in the present invention, and may be appropriately set and selected according to a conventionally known PDP front plate.

  Next, the present invention will be described more specifically with reference to examples and comparative examples.

Example 1
An electrode pattern was printed on a transparent substrate (a 42-inch diagonal glass substrate) for a PDP front substrate using a conductive metal ink.

Conductive metal ink 100 parts by weight of acrylic resin, 1600 parts by weight of silver powder having an average particle diameter of 1 μm, 50 parts by weight of bismuth oxide glass frit having an average particle diameter of 3 μm, and a solvent (60 parts by weight of butyl carbitol acetate and 15 carbon atoms) The mixed solvent (120 parts by weight of higher alcohol) was mixed and dispersed using three rolls to produce a conductive metal ink (ink for forming a bus main electrode constituting a PDP front plate electrode).

Measurement of ink viscosity The viscosity of the above conductive metal ink was measured using a parallel plate viscometer (manufactured by Rheology Co., Ltd., Solid Liquid MR-500) at a temperature of 23 ° C. and a relative humidity of 55% at a shear rate of 1 sec ^−1. When the viscosity was measured at ₁₀ sec ⁻¹ , they were 40 Pa · s (η ₁ ) and 8 Pa · s (η ₁₀ ), respectively. Therefore, the thixo value represented by η ₁ / η ₁₀ of this ink is 5.

-Printing of electrode pattern By the intaglio offset printing method, the conductive metal ink filled in the intaglio was transferred to a printing blanket, and then transferred from the blanket to the transparent substrate, thereby forming an electrode pattern by printing.

  As the intaglio plate for offset printing, a glass substrate having a stripe pattern (concave portion) having a line width of 90 μm, a line interval (pitch) of 360 μm, and a depth of 35 μm was used.

  The printing blanket used was a silicone rubber [rubber hardness JIS A: 40, thickness: 300 μm, surface roughness (ten-point average roughness Rz): 0.1 μm] as a surface rubber layer. As the silicone rubber, a room temperature curable addition type silicone rubber (product name “KE1600” manufactured by Shin-Etsu Chemical Co., Ltd.) was used.

  In printing the electrode pattern, the conductive metal ink filled in the intaglio was transferred onto the blanket at a transfer rate of 50 to 200 mm / sec in a clean room adjusted to a room temperature of 23 ° C. ± 1 ° C. Next, the surface was dried by blowing hot air at 100 ° C. for 20 seconds, and then cooled by forcibly blowing cold air at 10 ° C. over the blanket surface for 5 minutes. The surface temperature of the blanket after cooling was in the range of room temperature + 3 ° C. After the cooling treatment, the ink pattern on the blanket was transferred to the glass substrate to print the intended electrode pattern.

As a result, viscosity eta ₁₀ prepared in above by using an electrically conductive metal ink is 8 Pa · s, where the transition speed V has the electrode pattern and intaglio offset printing in the range of 50 to 200 mm / sec, both ink 100% of the electrode pattern was completely transferred onto the blanket, and an electrode pattern having a very good printing shape and a stable film thickness could be printed. All of the printed patterns had a line width of 75 μm, and the film thickness after firing was 1.5 μm.

Comparative Example 1
In the preparation of the conductive metal ink of Example 1, an ink was prepared in the same manner except that a mixed solvent of 30 parts by weight of butyl carbitol acetate and 150 parts by weight of a higher alcohol having 15 carbon atoms was used as a solvent. The ink has a viscosity at a shear rate of 1 sec ^-1 and 10 sec ^-1 were respectively 40Pa · s (η ₁₎ and 22Pa · s (η _10). Using this ink, intaglio offset printing was performed at a transfer speed V of 50 mm / sec and 100 mm / sec in the same manner as in Example 1. As a result, good printing was achieved at a transfer speed V of 50 mm / sec. At 100 mm / sec, pinholes and disconnections were conspicuous and good printing could not be performed.

  The present invention is useful for manufacturing an electrode for a plasma display panel.

It is a perspective view which shows an example of the structure of PDP. The range which satisfies the relationship of Formula (1) in this invention is represented with a graph, and the hatched range corresponds.

Explanation of symbols

10 PDP front electrode plate 11 Bus electrode 11a Black electrode 11b Bus main electrode 12 Transparent electrode (ITO)
13 Dielectric layer 15 Transparent substrate

Claims (5)

When forming an electrode pattern for a plasma display panel on a substrate by using an intaglio offset printing using a printing blanket having a silicone rubber surface rubber layer, an electrode forming ink made of a conductive metal ink or a black ink is used. A step of transferring the forming ink from the intaglio to a printing blanket, and a step of transferring the ink from the blanket to the substrate. A transfer speed V (mm / sec) in the transfer process and a shear rate of the ink of 10 sec ^−1. The relationship with the viscosity η ₁₀ is represented by the formula (1):
(6-0.02V) ≦ η ₁₀ ≦ (30-0.1V) (1)
[However, 0 <V <300, and η ₁₀ is the viscosity (Pa · s) of the ink measured by a parallel plate viscometer. The electrode pattern for a plasma display panel is printed so as to satisfy the above requirements.   The blanket has a surface rubber layer having a hardness represented by JIS-A of 20 to 80 ° and a surface roughness represented by ten-point average roughness (Rz) of 0.01 to 3.0 μm. 2. The method for printing an electrode pattern for a plasma display panel according to claim 1, wherein the electrode pattern is made of rubber.   2. The electrode pattern for a plasma display panel according to claim 1, wherein the electrode forming ink is a black ink containing at least a conductive metal powder, a black metal powder, a glass frit and an organic component capable of being removed by baking. Printing method.   2. The method for printing an electrode pattern for a plasma display panel according to claim 1, wherein the electrode forming ink is a conductive metal ink containing at least a conductive metal powder, glass frit and an organic component capable of being removed by baking.   5. The method for printing an electrode pattern for a plasma display panel according to claim 3, wherein the conductive metal powder is silver powder.

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