JP2005103754A - Blanket for offset printing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a blanket for intaglio offset printing suitable for continuously printing a highly precise pattern such as a PDP electrode or the like. <P>SOLUTION: The blanket for offset printing is produced by laminating a surface printing layer of a silicone rubber on a support layer composed of a synthetic resin or a metal film. The interface between the surface printing layer and the support layer is provided with a metal thin film having heat ray reflectivity (gold, chromium, aluminum, nickel, copper or silver), and more preferably contains inorganic metal fine particles having heat absorption properties in the surface rubber layer. The inorganic metal fine particles contains a tin oxide, antimony-doped indium oxide, indium-doped tin oxide or antimony pentaoxide having a primary particle diameter of not bigger than 0.5 μm. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an offset printing blanket, and more particularly to an offset printing blanket suitable for continuously printing a high-resolution and high-precision pattern required in an electronic circuit, an image forming apparatus, or the like.

  Conventionally, as a method of forming a pattern such as an electronic circuit in an integrated circuit or a color filter of a liquid crystal display, for example, in the case of an electrode pattern of a PDP electrode substrate, a photosensitive silver paste is applied to a glass surface, and the electrical conductivity is applied thereon. It is mainly formed by a method called a photolithographic method (photolithographic method) in which a photosensitive silver paste having a good conductivity for compensation is coated to a certain thickness, and after exposure, development is performed after drying. However, in this method, a large amount of expensive photosensitive black paste and silver paste that are not exposed are washed away during development, and disposal processing and high cost are problems.

  In recent years, a printing method has been studied as a method for forming an electrode at a low cost. In particular, intaglio offset printing has been promoted from the viewpoint of printing accuracy and ink film thickness. (See Patent Document 1). Intaglio offset printing is performed in the order of ink filling to the intaglio, transfer to the blanket, and transfer to the substrate, and the blanket is usually a laminate in which a rubber layer (surface printing layer) is laminated on the surface of the support layer. It consists of a body and is used by attaching it to a blanket cylinder of a printing press. In offset printing of a fine pattern such as a PDP electrode pattern, it is required for industrial production that continuous printing can be performed while maintaining precision printing.

  According to Patent Document 1, a conventional blanket for printing a fine pattern is a substrate (support) made of a base fabric and a compressible layer, and a surface rubber layer is formed, and the total thickness is 1.5 to 2.0 mm. Since it is easy to cause tension variation when the blanket is mounted and affects the printing performance, the substrate film and the surface rubber layer provided on the surface thereof are provided, and the thickness of the substrate film is in the range of 5 to 50 μm. And a blanket in which the thickness of the surface rubber layer is in the range of 10 to 500 μm has been proposed.

  On the other hand, when applying intaglio offset printing to fine pattern printing, the solvent in the electrode pattern forming ink penetrates into the rubber constituting the surface printing layer of the blanket during continuous printing, and the rubber is swollen to form the surface rubber. It is known that the wettability of ink changes, the printing line width changes, and the printing performance deteriorates. For this reason, in manufacturing an electrode substrate for PDP by offset printing, a printing method has been developed in which the blanket surface is heated to sufficiently dry the solvent and then cooled so that the surface temperature does not rise above a predetermined temperature after drying. (See Patent Document 2).

The pattern printing of the electrode substrate for PDP in Patent Document 2 includes (i) a step of transferring the conductive ink composition from the concave portion of the intaglio to the surface of the printing blanket, and (ii) the conductive ink composition of the printing blanket. After passing through the step of transferring from the surface to the surface of the glass substrate, the step of heating the surface of the printing blanket and evaporating and removing the solvent of the ink from the surface printing layer is performed. At this time, examples of a simple method of heating the printing blanket include a method of blowing hot air or hot air from the outside of the printing blanket or heating the surface printing layer. As the heating element, for example, an infrared heater or a lamp that can be heated / not heated from the outside is conveniently used.
JP-A-10-86549 (Claims 1-7) JP 2002-245931 A (Claim 1, FIG. 2, etc.)

  According to the method of Patent Document 1, a fine pattern such as a PDP electrode can be continuously printed with high accuracy by offset printing. However, in terms of productivity improvement, it takes time to dry and cool the blanket surface. It is desired to shorten as much as possible and to efficiently use heat energy. Therefore, an object of the present invention is to improve the performance of the offset printing blanket from this point of view, and to develop the continuous printing of a fine pattern further industrially advantageously.

  In order to solve the above-mentioned problems, the present inventors conducted extensive research and found that most of the heat source used for drying the blanket surface heated the blanket cylinder made of metal in addition to heating the surface rubber layer (surface printed layer). Turned out to be consumed. As a result of further research, we found that if a metal thin film layer that reflects infrared rays is formed at the interface between the support layer and the surface rubber layer, the heat conduction from the blanket to the metal cylinder can be cut off. Based on this, the following offset printing blanket of the present invention has been completed.

1) Offset printing blanket obtained by laminating a surface printing layer made of silicone rubber on a support layer, and comprising a heat ray reflective metal thin film at the interface between the surface printing layer and the support layer Blanket.
2) The blanket for offset printing according to 1) above, wherein the material of the metal thin film is gold, chromium, aluminum, nickel, copper or silver.

3) The blanket for offset printing according to 1) or 2) above, wherein the surface printing layer contains inorganic metal fine particles having heat-absorbing ability.
4) The inorganic metal fine particles have a primary particle size of 0.5 μm (micrometer) or less, tin oxide, antimony-doped tin oxide, indium-doped tin oxide, antimony pentoxide, vanadium oxide, anhydrous zinc antimonate gel, The blanket for offset printing according to 3) above, which is one or more metal oxides selected from the group consisting of titanium oxide, zinc oxide, indium oxide and zinc sulfide.

5) The above 1) to 4), wherein the support layer is composed of a synthetic resin film or a metal film having a breaking elongation of 5 to 200% and a breaking strength of 150 to 1000 MPa when measured according to the measurement method specified in JIS C2151. The blanket for offset printing described in any one of the items).
6) The synthetic resin film is made of a polyester resin, a polycarbonate resin, a polyimide resin, an acrylic resin, a urethane resin, a polyamideimide resin, and a polyethersulfone resin, or one or more mixed resins. The blanket for offset printing as described in 5) above.

  The offset printing blanket of the present invention (hereinafter sometimes simply referred to as a blanket) is characterized in that a heat ray reflective metal thin film is provided at the interface between the support layer and the surface printing layer. For this reason, especially when printing fine patterns such as electrodes for PDP, the heat ray from the heating element can be used effectively and the cooling time etc. can be shortened when continuously printing the blanket surface while heating and drying and cooling. As a result, productivity can be improved and heat energy can be saved. This effect is further enhanced by including inorganic metal fine particles having heat ray absorbing ability in the silicone rubber constituting the surface print layer.

Hereinafter, the configuration of the blanket of the present invention and the materials used will be described.
The material of the metal thin film is preferably gold, chromium, aluminum, nickel, copper or silver, and may be either a single layer thin film made of one of these metals or a multilayer thin film made of two or more kinds. Among these metal materials, gold, chromium, or aluminum is more preferably used because it has a high reflectance particularly in the near infrared region.

  As a method for forming the metal thin film, a means known per se (for example, a method described in JP-A-10-100310) can be used. For example, vacuum deposition, a spudder method, an ion plating method, electroplating, electroless It can be carried out by plating or printing. Among these forming methods, in particular, vacuum deposition, spudder method, and ion plating method form a thin film having an extremely smooth surface, so that the reflectance is high and the reflection of heat rays is also good. In general, the thickness of the metal thin film is preferably about 0.03 to 3 μm, more preferably about 0.05 to 1 μm. If the thickness is less than this range, heat rays are likely to be transmitted. On the other hand, if the thickness is larger than this range, the efficiency of heat reflection does not change, which is disadvantageous as the material cost increases.

  In order to wet the surface of the surface rubber layer and evaporate the solvent penetrating into the blanket of the present invention by utilizing a heat source irradiated during printing, the blanket of the present invention includes a metal thin film in addition to the above-mentioned metal thin film. It is more advantageous to contain inorganic metal fine particles that absorb heat rays. Due to the presence of the inorganic metal particles, the transmission of heat ray energy to the blanket cylinder is well prevented by the metal thin film, and the effect of strengthening the drying of the solvent in the silicone rubber constituting the surface printing layer is exerted more strongly.

  As the material of the inorganic metal fine particles, tin oxide, antimony-doped tin oxide (ATO), indium-doped tin oxide (ITO), antimony pentoxide, vanadium oxide, anhydrous zinc antimonate gel, titanium oxide, zinc oxide, indium oxide and sulfide One or more metal oxides selected from the group consisting of zinc are preferably used. Among these, tin oxide, antimony-doped tin oxide, indium-doped tin oxide, antimony pentoxide or vanadium oxide is more preferably used because of its excellent ability to absorb far-infrared rays of 1200 nm or less.

  The particle diameter of these inorganic metal fine particles is, if contained in the silicone rubber, if the particles are too large, it becomes difficult to smooth the surface of the printing surface layer, and consequently adversely affects the printing shape, etc. It is advantageous to be in a fine powder state, and fine particles having a primary particle diameter of usually 0.5 μm or less are blended. The amount of inorganic metal fine particles added to the surface rubber layer is preferably 20 to 500 parts by weight, more preferably 50 to 250 parts by weight, based on 100 parts by weight of rubber.

  The surface printing layer of the blanket of the present invention preferably has a surface energy value of 15 to 30 dyn / cm in a dry state that does not contain an ink solvent. More preferably, it is ˜25 dyn / cm. Considering this, the surface printing layer of the blanket of the present invention is formed of silicone rubber. The blanket whose surface printing layer is made of silicone rubber has extremely excellent ink releasability, and can transfer almost 100% of the ink transferred from the intaglio.

  Examples of the silicone rubber include various types of silicone rubbers such as a heat curable type (HTV) and a room temperature curable type (RTV). In particular, a room temperature curable addition type silicone rubber does not generate any by-product during curing. Since it is excellent in dimensional accuracy, it is preferably used. Specific examples of such silicone rubber include dimethyl silicone rubber, methylphenyl silicone rubber, trifluoropropylmethyl silicone rubber and the like.

  The hardness of the surface printed layer is about 20 to 80 °, particularly about 30 to 60 ° in terms of spring-type hardness (JIS A) defined in Japanese Industrial Standard JIS K 6301, considering printing accuracy and the like. Is preferred. If the hardness of the surface printing layer exceeds the above range, the blanket is too hard and the surface printing layer is not fully press-fitted into the recess even when pressed against the intaglio, so that the conductive ink composition filled in the recess There is a possibility that an object cannot be transferred sufficiently and printing with high accuracy cannot be performed. On the contrary, if the hardness of the surface printing layer is below the above range, the blanket is too soft and the surface printing layer may be deformed too much when pressed against an intaglio or glass substrate, which may prevent accurate printing. is there.

  It is preferable that the surface of the blanket is extremely smooth from the viewpoint of printing accuracy and the like, and the unevenness or the like on the surface does not affect printing. Specifically, the ten-point average roughness (Rz) of the surface is preferably 1.0 μm or less, and more preferably 0.5 μm or less. Moreover, it is preferable that the thickness of a surface printing layer is the range of 50-1500 micrometers. If this thickness is not reached, it is not sufficient for accepting and transferring ink with good printing performance, and if it exceeds 1500 μm, deformation of the rubber becomes large, which may adversely affect pattern printing accuracy. Absent.

  Next, in the blanket of the present invention, the support layer constituting the lower layer of the surface print layer is required to be made of a material having as little elongation as possible and high strength and a smooth surface. In general, a cotton cloth is often used for the support layer of the offset printing blanket. However, in the case of precision printing such as a PDP electrode pattern, the cotton cloth generates fibrous dust during printing, and the printing performance is improved. It is desirable not to use it because it lowers. In the present invention, the support layer is preferably composed of a synthetic resin film or a metal film having a breaking elongation of 5 to 200% and a breaking strength of 150 to 1000 MPa when measured by the measurement method specified in JIS C2151. .

  As a material of the synthetic resin film, one or two or more mixed resins selected from the group consisting of polyester resin, polycarbonate resin, polyimide resin, acrylic resin, urethane resin, polyamideimide resin, and polyethersulfone resin are used. Preferably used. Further, as the material of the metal film, a metal material such as stainless steel, nickel, iron, or an alloy thereof is preferably used.

  When the film is used as a blanket support layer, the thickness depends on the strength of the material, but it is preferably about 100 to 500 μm as a practically small thickness. If it is thinner than this, it will be stretched when it is attached to the blanket cylinder or during printing, and if it is thicker than this, it will become hard and the attachment to the blanket cylinder will be poor. For example, in the blanket of Patent Document 1, a base film having a thickness of 5 to 50 μm is supposed to be used. However, at such a thickness, the blanket cylinder is stretched when applied to the blanket cylinder during use. It is not suitable for performing intaglio offset printing intended for use. The total thickness of the lanquet of the present invention is preferably in the range of 0.1 to 5.0 μm, and more preferably in the range of 0.5 to 2.0 μm.

In the blanket of the present invention, since the metal thin film is present at the interface between the support layer and the surface printing, the metal thin film is usually formed on the surface of the base film constituting the support layer, and then the silicone rubber layer For example, by a casting method using a mold.
Next, an intaglio offset printing method using the blanket of the present invention will be described. This blanket is suitable for continuous printing of high-resolution and high-precision patterns required in electronic circuits and image forming apparatuses. As a representative example, a case where pattern printing is performed on an electrode substrate for a PDP electrode will be described as an example.

  For example, as shown in FIG. 1, the PDP includes a back substrate (rear substrate) 11 provided with an address electrode (Ag) 10, a dielectric layer (glass) 16 ′ and a protective layer (MgO) 17 ′, a transparent electrode 14, and a bus. The electrode 15, the transparent dielectric layer 16, and a front substrate (front substrate) 18 having a protective layer (MgO) 17 are faced to each other. On the back substrate 11, ribs (partition walls) 12 and phosphors 13 (R, G, B) are formed on the surface of the protective layer 17 ′.

  In manufacturing the electrode substrate for PDP, the blanket of the present invention is prepared by filling the concave portion of the intaglio with a conductive ink composition in which a metal powder and a binder resin are dispersed or dissolved in a solvent. Advantageous for offset printing of the electrode pattern by the step of transferring the ink composition from the concave portion of the intaglio to the surface of the blanket, and (ii) the step of transferring the conductive ink composition from the surface of the blanket to the surface of the glass substrate. Used for. In this offset printing, by applying a heat treatment at a predetermined temperature to the blanket, a fine pattern required for the electrode substrate for PDP can be formed with high accuracy, and by the heat treatment, Deterioration of printed shape and pinholes due to blanket swelling can be prevented. As a result, high productivity can be exhibited when manufacturing an electrode substrate for PDP. Further, after the heat treatment, the surface of the intaglio Since the printing blanket is cooled so that the temperature does not rise above a predetermined range with respect to the temperature, the intaglio is expanded by the heat remaining in the printing blanket, and accordingly the printed shape of the pattern is reduced and pinholes Can be prevented.

When the blanket of the present invention is used, the heat treatment and the cooling treatment can be performed in a short time, and the heat energy can be used effectively. A pattern made of a conductive ink composition formed on the surface of the glass substrate is baked by a conventional method, and the binder resin content of the pattern is removed to produce a target PDP electrode.
The intaglio used as an original plate at the time of printing and forming a conductive pattern has a concave portion corresponding to the electrode pattern formed on the surface thereof, a flat plate, or a flat plate wound around a cylinder, A cylindrical thing, a cylindrical thing, etc. are mentioned. In the intaglio, the smoothness of the surface is extremely important. If the surface of the intaglio plate is not smooth enough, when the conductive ink composition is filled into the recesses with a doctor blade, ink scraps are generated on the surface of the intaglio plate (other than the recesses), and stains on the non-image area (ground) Smudges), and the printing accuracy is significantly reduced.

  The degree of smoothness of the intaglio surface is preferably about 1 μm or less, more preferably about 0.5 μm or less in terms of ten-point average roughness (Rz). Examples of intaglio substrates include glass substrates such as soda lime glass, non-alkali glass, quartz glass, low alkali glass, and low expansion glass; fluororesin, polycarbonate (PC), polyethersulfone (PES), polyester, Resin plates such as polymethacrylic resin; metal substrates such as stainless steel, copper, nickel, and low expansion alloy amber. Among them, a glass substrate is preferably used because an intaglio having excellent surface smoothness can be produced most inexpensively and the pattern edge shape can be made extremely sharp. Among the above-mentioned intaglio plates, non-alkali glass is one of the most excellent materials that can meet the requirements for extremely high dimensional accuracy, but is very expensive. For example, soda lime glass is sufficient to achieve the dimensional accuracy required for a normal PDP.

  The concave portion of the intaglio is formed by a photolithographic method, an etching method, an electroforming method, a sand blast method (shot blast method), or the like. As described above, the depth of the concave portion may be appropriately set according to the thickness of the target print pattern. However, the ink remaining in the concave portion (usually about half the amount of ink with respect to the depth of the concave portion). In consideration of a decrease in thickness after printing due to evaporation of the solvent, etc., it is preferably about 1 to 50 μm, particularly about 3 to 20 μm.

  Therefore, in performing offset printing, (i) a step of transferring the conductive ink composition from the concave portion of the intaglio to the surface of the printing blanket; and (ii) the conductive ink composition from the surface of the printing blanket to the glass substrate. And a step of transferring the surface to the surface of the blanket, followed by a step of heating the blanket surface and evaporating and removing the ink solvent from the surface printed layer.

Since the solvent that has penetrated into the surface print layer of the blanket is evaporated and removed by heating the surface print layer, it can be completely returned to the original dry surface state. The easiness of evaporation and drying of the surface print layer is related to the heating temperature, the characteristics of the solvent of the conductive ink composition (particularly the boiling point), and the thickness of the surface print layer. If it heats so that it may become 40-200 degreeC, it can dry sufficiently effectively.

Blanket surface temperature during heating When the temperature is lower than 40 ° C., the effect of evaporating and removing the solvent that has permeated the surface print layer becomes insufficient. Meanwhile, blanket surface temperature during heating When the temperature exceeds 200 ° C., the rubber constituting the surface print layer is thermally deteriorated and modified. Surface temperature T _B of the heating time of the blanket, in particular among the above range is preferably from 60 to 150 ° C., and more preferably 80 to 120 ° C..

  Conventionally, the blanket is heated by placing a heating device inside the blanket cylinder to heat the entire printing blanket, blowing hot air or hot air from the outside of the blanket, or under the blanket itself or the blanket and blanket. For example, a heating element layer may be disposed between the body and the surface printing layer may be heated from the heating element layer. When the blanket of the present invention is used, a simple method of irradiating and drying the surface printed layer is adopted as the heating element, for example, using a flexible infrared heater or lamp capable of external heating / non-heating operation. Sometimes, since the heat rays can be used effectively, shortening of the heating time and energy consumption can be suppressed.

  The heat treatment of the blanket can be always performed when the conductive pattern is printed, but it may be performed periodically after repeating the above steps (i) and (ii) several times. Alternatively, it may be performed irregularly depending on the degree to which the blanket is swollen by the solvent of the conductive ink composition. The degree of the heat treatment of the blanket is not particularly limited, but the rate of change in the surface tension of the surface treatment layer is adjusted to be -30 to 30% with respect to the dry state (initial state). Is preferred. By adjusting in this way, the extent to which the blanket absorbs the solvent of the ink can be kept almost constant at a state close to the initial state at all times, preventing deterioration of the pattern shape over time, and excellent for a long time It becomes possible to demonstrate printing accuracy.

Blanket surface temperature Is maintained in the state of being raised by the heat treatment, there is a problem in that the thermal expansion of the intaglio is caused by the contact between the blanket and the intaglio in the printing process, leading to a decrease in printing accuracy. . Intaglio surface temperature Usually, it is necessary to keep the temperature change within ± 1 ℃, and the blanket surface temperature It is necessary to keep the change in a predetermined range.

A method for cooling the surface of the blanket is not particularly limited, but it is most effective to forcibly cool the surface of the printing blanket with cold air. Generally, the blanket cylinder is made of metal and has a large heat capacity. In the conventional blanket, heat transfer to the lanquet cylinder is large, and this cooling takes time.
As described above, the conductive ink composition used for offset printing is a paste in which metal powder and a resin binder are dispersed or dissolved in a solvent. Examples of the metal powder include silver, copper, gold, nickel, aluminum, and iron. These metal powders can be used alone or in combination of two or more. Moreover, it can also be used as a plating composite (for example, silver plating copper) or an alloy body.

  Among the metal powders exemplified above, silver powder is most preferable from the viewpoints of conductivity, cost, oxidation resistance (characteristic that hardly generates an oxide having high insulating properties), and the like. The average particle diameter of the metal powder is preferably about 0.05 to 20 μm, more preferably about 0.1 to 10 μm, considering the printability of the conductive ink composition. The shape of the metal powder is not particularly limited, but it is more preferably a scaly shape than a spherical shape from the viewpoint of increasing the contact area of the powder and enabling a reduction in resistance. In order to close-pack the metal powder, it is also effective to use a mixture of flaky particles and spherical particles.

  The packing density of the metal powder in the conductive ink composition can suppress the volume change when the conductive pattern is baked into an electrode pattern as much as possible, and the content ratio of the metal powder in the baked electrode pattern can be achieved. From the viewpoint of increasing the amount as much as possible, it is desired that the conductive ink composition be made higher if it is within a range where the printability of the conductive ink composition can be sufficiently maintained. The amount of the metal powder added to the conductive ink composition is not particularly limited, but is preferably about 60 to 95% by weight, preferably 80 to 90% by weight based on the total amount of the conductive ink composition. More preferably, it is about%. When the addition amount of the metal powder is below the above range, there arises a problem that the packing density of the metal powder after firing does not increase and the resistance of the conductive pattern does not decrease. Conversely, if the amount of the metal powder added exceeds the above range, the binding strength of the binder resin that bonds the metal powders is weakened, and the printability of the conductive ink composition is reduced, resulting in deterioration of the printing shape and printing. There is a risk of lowering the transferability from the blanket to the glass substrate.

It is preferable to add a black metal such as a black metal oxide or a black composite alloy to the conductive ink composition in consideration of blackness in order to improve the contrast when forming the PDP front electrode. . The black metal oxide or black composite alloy may be any metal that is black at room temperature, does not change color even when fired at a temperature of 500 to 700 ° C. for 5 to 60 minutes, and does not decompose or sublime. 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.

  Any of various resins such as a thermosetting resin, an ultraviolet curable resin, and a thermoplastic resin can be used as the binder resin constituting the conductive ink composition. Examples of the thermosetting binder resin include polyester-melamine resin, melamine resin, epoxy-melamine resin, phenol resin, polyimide resin, thermosetting acrylic resin, and the like. Examples of the ultraviolet curable binder resin include an acrylic resin. Examples of the thermoplastic binder resin include polyester resin, polyvinyl butyral resin, cellulose resin, and acrylic resin. The above exemplified resins can be used alone or in combination of two or more.

Among the resins exemplified above, a resin that is completely decomposed into carbon dioxide (CO ₂ ) and water (H ₂ O) when fired at a high temperature of 300 ° C. or higher is preferably used. Examples of such a resin include thermoplastic polyvinyl butyral resin, cellulose resin (ethyl cellulose), and acrylic resin. The amount of the binder resin added to the conductive ink composition is preferably about 0.5 to 50% by weight, and about 1 to 30% by weight, expressed as a percentage of the total amount of the conductive ink composition. Is more preferable. If the added amount of the binder resin is less than the above range, the binding power of the binder resin for bonding metal powders is weakened, and the printability of the conductive ink composition (transfer of ink from the pattern printing shape, printing blanket, etc.) May be reduced. On the contrary, when the addition amount of the binder resin exceeds the above range, there arises a problem that the electric resistance of the electrode pattern after firing cannot be lowered.

  The solvent constituting the conductive ink composition is an important factor that governs the printability in intaglio offset printing. In particular, as already mentioned, the ink solvent always comes into contact with the surface printing layer of the blanket during printing, so that the surface printing layer swells with the solvent and changes the wetting properties of its surface. In general, when the degree of swelling by the ink solvent is small, there is little change in the wettability of the surface of the blanket, and as a result, stable printing is possible.

  The solvent of the conductive ink composition is appropriately set according to the type of the surface print layer of the printing blanket used for printing the conductive pattern. The solvent used in the conductive ink composition is not limited to this, but the volume of the rubber increases when the rubber constituting the surface printing layer of the printing blanket is immersed at room temperature (23 ° C.) for 24 hours. It is preferable that the rate (swelling rate) is 20% or less, preferably 10% or less.

  Other requirements required for the solvent used in the conductive ink composition are not limited thereto, but for example, those having a boiling point of 150 ° C. or higher are preferable. 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. The amount of the solvent added is preferably adjusted so that the viscosity of the conductive ink composition is about 50 to 2000 poise (P), preferably about 200 to 1000 P. If the viscosity of the conductive ink composition is below the above range or exceeds the above range, in any case, the printability of the conductive ink composition may be reduced and a fine pattern may not be formed. Because there is.

As a glass substrate which forms the printing pattern by the said conductive ink composition, soda lime glass, non-alkali glass, quartz glass, low alkali glass, low expansion glass etc. are mentioned, for example.
Moreover, it is more preferable to use a glass with a high strain point (temperature) in consideration of subjecting the pattern to a step of baking the pattern at a high temperature. Specifically, the strain point is preferably 500 ° C. or higher. Therefore, it is particularly preferable to use high strain point glass (low alkali glass) among the above exemplified glasses. Specific examples of the high strain point glass include a product number “PD200” manufactured by Asahi Glass Co., Ltd. and a product number “PP8C” manufactured by Nippon Electric Glass Co., Ltd. The thickness of the substrate is appropriately set according to the heat resistance of the substrate and is not particularly limited, but the thickness is appropriately set in the range of 1 to 10 mm.

  The line width and thickness of the conductive pattern formed by printing the conductive ink composition are set according to the size of the pixel of the PDP and the like, and taking into account the amount reduced by firing. Therefore, although not particularly limited, in general, in the case of a back substrate, the line width is set to 40 to 100 μm, preferably 50 to 70 μm. Further, the thickness of the pattern is usually set to be 3 to 30 μm, preferably 5 to 20 μm.

  On the other hand, in the case of the front substrate, the pattern of the front electrode (bus electrode) formed by the method of the present invention is required to be thinner and finer than the address electrode formed on the back electrode. Specifically, the line width is set to 20 to 70 μm, preferably 30 to 50 μm. Further, the thickness of the pattern is usually set to be 3 to 30 μm, preferably 5 to 20 μm.

  The conductive pattern printed and formed on the back substrate is further heated to 450 to 650 ° C., preferably 500 to 600 ° C., and baked. By such firing, the solvent in the conductive ink composition evaporates, and the binder resin disappears due to thermal decomposition. Thus, an electrode pattern made of metal can be obtained according to the pattern shape of the conductive pattern.

Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples.
Example 1
A blanket for offset printing was produced as follows. Silicone rubber (“KE1600” room temperature curing type-addition type dimethyl silicone rubber manufactured by Shin-Etsu Chemical Co., Ltd.) is 0.9 mm in thickness, and ITO fine powder having a primary particle diameter of 0.2 μm is added to 100 parts by weight of rubber. On the other hand, 150 parts by weight was added to form a surface rubber layer. On the other hand, a polyethylene terephthalate (PET) film having a thickness of 0.3 mm (breaking elongation: 150%, breaking strength: 250 MPa, both according to the measurement method specified in JIS C2151) was used as the support layer, and the thickness was 0 on the surface. A 1 μm aluminum film was formed by vacuum deposition. In producing the blanket, a method was used in which a silicone rubber containing fine ITO powder was laminated on the support by a casting method using a mold whose surface was precisely polished. A highly smooth blanket having a total blanket thickness of 1.20 mm and a surface printed layer having a surface roughness of 10 μm average roughness (Rz) of 0.1 μm was produced.

Using the printing blanket obtained in Example 1, a pattern of conductive paste ink was formed on the front panel (42 inches diagonal) of the PDP by offset printing. Here, the line width of the intaglio was 80 μm, the pitch was 360 μm, the depth was 25 μm, and the printed material was high strain point glass for PDP (“PD200” manufactured by Asahi Glass Co., Ltd.). The conductive paste ink is prepared by mixing and dispersing acrylic resin (100 parts by weight), silver powder (1600 parts by weight), glass frit (50 parts by weight), and organic solvent (200 parts by weight of butyl butyl carbitol). It was prepared by kneading using this roll, and at the final stage, a solvent (butyl carbitol acetate) was added to adjust the viscosity to 250 poise (shear rate 10 s ⁻¹ ).

  The blanket of Example 1 was affixed to the blanket cylinder of a printing machine (flat bed sheet type precision printing machine), and the pattern was printed. For each printing, the blanket surface was heated and dried by applying hot air of 100 ° C. for 20 seconds. The clean room for printing was controlled at a room temperature of 23 ° C. ± 1 ° C., and the surface temperature of the intaglio was within this temperature range. The blanket surface after drying was forcibly cooled by applying cold air of 10 ° C. for 20 seconds. Under this printing condition, 10,000 PDP electrode patterns were continuously printed.

  As a result, in heat drying of the blanket surface, most of the heat rays are reflected by the aluminum deposition surface, the ITO fine powder contained in the silicone rubber layer efficiently absorbs near infrared rays, and dries the solvent that has penetrated into the rubber. I was able to. Therefore, even if drying and cooling are repeated, the temperature rise of the blanket cylinder itself is kept within 1 ° C. after printing 10,000 sheets, the line width variation is within ± 3 μm, and printing of a pattern with a stable film thickness is continued. I was able to. That is, it is possible to produce a PDP electrode with a stable line width, film thickness, and resistance, and there is no problem in mounting the PDP panel, and it is possible to form a front electrode with very good conductivity. It was. In addition, the amount of ink used is reduced, and no waste liquid or the like is generated as compared with the photolithography method, and the equipment is inexpensive. Therefore, the production cost can be reduced.

Example 2
A blanket for offset printing was produced as follows. Silicone rubber (“KE1600” manufactured by Shin-Etsu Chemical Co., Ltd.) was 0.9 mm in thickness to form a surface rubber layer. On the other hand, a polyethylene terephthalate (PET) film having a thickness of 0.3 mm (breaking elongation: 150%, breaking strength: 250 MPa, both according to the measurement method specified in JIS C2151) was used as the support layer, and the thickness was 0 on the surface. A 1 μm aluminum film was formed by vacuum deposition. In producing the blanket, a method was used in which a silicone rubber containing fine ITO powder was laminated on the support by a casting method using a mold whose surface was precisely polished. A highly smooth blanket having a total blanket thickness of 1.20 mm and a surface printed layer having a surface roughness of 10 μm average roughness (Rz) of 0.1 μm was produced.

Using the printing blanket obtained in Example 2, a pattern made of conductive paste ink was formed by offset printing on the front plate (42 inches diagonal) of the PDP by the same method in Example 1 described above.
As a result, in the heat drying of the blanket surface, most of the heat rays were reflected by the aluminum deposition surface, and the solvent that had penetrated into the silicone rubber could be efficiently dried. Therefore, even if drying and cooling are repeated, the temperature rise of the blanket cylinder itself remains within 3 ° C. after printing 10,000 sheets, and the line width variation is within ± 5 μm, and printing of a pattern with a stable film thickness is continued. I was able to.

Comparative Example 1
In Example 1, a blanket for printing was prepared without subjecting the PET film to aluminum vapor deposition, and without mixing ITO fine powder into the silicone rubber.
Using the printing blanket produced in Comparative Example 1, PDP electrode patterns were continuously printed under the same conditions as in Use Example 1. As a result, printing was possible without any major problems at the beginning of printing, but the temperature of the blanket cylinder gradually increased and reached about 5 ° C. higher than the intaglio surface at the time of printing 1000 sheets. As a result, the printing accuracy also decreased, and after 1000 sheets were printed, the cooling speed was increased by increasing the blowing speed of the cold air and the cooling time from 20 seconds to 40 seconds. As a result, the temperature rise could be suppressed and the printability could be maintained, but the printing tact time became longer and the productivity deteriorated as compared with the use example 1.

  The blanket for offset printing of the present invention is suitable for continuous printing with fine printability such as PDP electrode pattern with good printability, and there is no problem of waste liquid treatment compared to the photolithography method, and greatly contributes to the reduction of production cost. can do.

It is a perspective view which shows an example of the back substrate of PDP.

Claims (6)

  A blanket for offset printing formed by laminating a surface printing layer made of silicone rubber on a support layer, the blanket for offset printing comprising a heat ray reflective metal thin film at the interface between the surface printing layer and the support layer .   The blanket for offset printing according to claim 1, wherein a material of the metal thin film is gold, chromium, aluminum, nickel, copper, or silver.   The blanket for offset printing according to claim 1 or 2, wherein the surface rubber layer contains inorganic metal fine particles having heat ray absorbing ability.   The inorganic metallic fine particles have a primary particle size of 0.5 μm or less, tin oxide, antimony-doped tin oxide, indium-doped tin oxide, antimony pentoxide, vanadium oxide, anhydrous zinc antimonate gel, titanium oxide, zinc oxide, The blanket for offset printing according to claim 3, wherein the blanket is one or more metal oxides selected from the group consisting of indium oxide and zinc sulfide.   The said support body layer has a synthetic resin film or a metal film whose breaking elongation is 5 to 200% and breaking strength is 150 to 1000 MPa when measured by the measuring method prescribed | regulated to JISC2151. Blanket for offset printing as described in 1.   The synthetic resin film is made of one or two or more mixed resins selected from the group consisting of polyester resin, polycarbonate resin, polyimide resin, acrylic resin, urethane resin, polyamideimide resin and polyethersulfone resin. The bracket for offset printing according to claim 5.

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