JP6167789B2 - Topographic printing device - Google Patents

Description

  The present invention relates to a relief printing apparatus for forming a functional thin film pattern with high quality.

  In recent years, in the formation of fine thin film patterns, attempts have been made to use a known printing method that is excellent in mass productivity and can keep the manufacturing cost low. In particular, in the display field, in order to cope with an increase in screen size and cost, studies are being made on patterning functional thin films such as organic semiconductors and conductive materials by printing methods.

  Furthermore, among various printing methods, organic semiconductors and conductive materials using glass as a substrate to be transferred are not suitable for methods using a hard metal printing plate as in the gravure printing method, and elastic rubber blankets are used. An offset printing method and a relief printing method using a rubber plate or a resin plate having elasticity are also suitable. Actually, as an attempt by these printing methods, a method by offset printing (Patent Document 1), a method by letterpress printing (Patent Document 2), and the like have been proposed.

  Among these various printing methods, the resin relief printing method using a relief printing plate made of resin, in particular, includes the relief printing plate, an ink supply roll in which fine recesses (cells) are engraved on the surface called an anilox roll, and a solvent-drying type ink. It is a printing method consisting of the above, and has been widely used for printed materials such as wrapping paper. This resin relief printing method is particularly suitable for forming a thin film having a thickness of about 30 nm to 200 nm.

  In addition, since the resin relief printing method can be printed at a very low printing pressure called kiss touch, it can be applied to a glass substrate or a substrate on which a transparent electrode or the like whose characteristics are easily destroyed by applying high pressure is formed. It is also suitable for printing, and is a printing method particularly suitable for pattern formation of electronic parts such as displays.

  FIG. 1 is a diagram illustrating an example of a conventional printing apparatus. Ink is stored in the ink chamber 703 shown in FIG. After ink is supplied to the anilox roll 704 in the ink chamber 703, excess ink on the surface of the anilox roll 704 is scraped off by the doctor blade 705, and the ink is stored only inside the hole of the anilox roll 704. The ink inside the hole is transferred to a relief plate 701 (resin relief plate) wound around a plate cylinder 702 that rotates relative to the anilox roll 704. Further, the thin film formed on the surface of the relief plate 701 is transferred onto a printing substrate 706 placed on a substrate surface plate 707 moving in the direction of arrow 708 relative to the plate cylinder 702 rotating in the direction of arrow 709. The

  Next, the flow of printing when using a relief printing apparatus will be described with reference to FIG. First, after the substrate to be printed 706 is placed on the substrate surface plate 707, the substrate surface plate 707 moves to just below the plate cylinder 702. If the substrate surface plate 707 moves, the plate cylinder 702 rotates synchronously with the operation of the substrate surface plate, and ink is supplied to the relief plate 701 from the anilox roll 704 operating at the same speed as the plate cylinder. After the ink is supplied to the relief plate 701, the ink on the relief plate 701 is quickly transferred to the printing substrate 706, and the printing operation is completed.

  In addition, as shown in FIG. 2, a doctor roll 710 may be used instead of the doctor blade 705.

  Next, the film thickness of the ink and printed matter when printing the high-functional organic material will be described.

  Examples of inks used as high-performance materials include high-molecular organic materials, etc., which have good solubility in organic solvents, particularly aromatic organic solvents, and are therefore used as inks using aromatic organic solvents. Is common. Among aromatic solvents, solvents with relatively simple addition groups to the aromatic ring, such as toluene, xylene, anisole, and tetralin, are more soluble in organic light-emitting materials, so the degree of freedom to set the solid content concentration of the ink Since it is high and there is little risk of precipitation or gelation during use or storage, it is more preferable as a solvent for highly functional organic material inks.

  An organic light emitting material ink using an aromatic organic solvent, especially an organic light emitting material ink using toluene, xylene, anisole or tetralin as a solvent becomes a liquid ink having a low viscosity. A system using the anilox roll 704 is suitable.

  The number of fine cells per unit area (cell density) formed on the surface of the anilox roll 704 is generally expressed by the number of lines (the number of cells existing per 2.54 cm (1 inch) length). However, as the number of lines increases, fine cells exist at a high density, so the uniformity of ink transfer to the plate is preferably high, but the volume per cell is small, and the cell volume per fixed area is also small. Therefore, if the number of lines is too high, the absolute amount of ink transfer becomes insufficient. Therefore, by selecting the number of lines of the anilox roll 704 appropriately and setting the ink solid content ratio corresponding thereto, an organic film layer having a uniform film thickness can be formed.

  When highly functional organic material ink is patterned with high accuracy, the specific number of lines of the anilox roll 704 and the solid content of the organic light emitting material ink vary depending on the type of the high functional organic material and the target film thickness. The ink solid content can be controlled within a range of 1% to 4% using an ink obtained by dissolving a polymer organic light emitting material in a toluene or xylene solvent.

  A method for managing the ink solid content ratio in the printing will be described. The ink solid content ratio is generally managed by using viscosity. Viscosity is a measure of how quickly an object deforms when a force is applied to an object. When the solids ratio of the polymer is dilute, each polymer chain is in solution. Although it is isolated, it is known that when the solid content ratio of the polymer is increased, the nearby polymer chains are entangled with each other so that they are difficult to rotate and the viscosity is increased. Thus, the solid content ratio and the viscosity value of the polymer are closely related.

  Since the relation between the solid content ratio and the viscosity mainly shows a quadratic curve as shown in FIG. 3, the solid content ratio is calculated using the viscosity value, and the film thickness is controlled after the toluene or xylene solvent is evaporated. It can be carried out. In addition, by using the viscosity value, it is possible to always convert the change in the solid content ratio of the ink during printing or after printing, such as the change in the solid content ratio due to evaporation of the solvent and the state of the ink after printing, using the viscosity value. There is.

  However, since the viscosity value changes with changes in temperature, it is necessary to measure and manage the temperature. For example, when the temperature of an organic light emitting material in which an organic EL (electroluminescence) material A is dissolved in a solvent B is increased, the viscosity decreases. As the temperature changes in this way, the intermolecular force of the ink solvent changes, greatly affecting the ink viscosity. Therefore, when the film thickness is controlled by the viscosity value, management for keeping the temperature constant is also necessary.

  In the above-mentioned letterpress printing method, ink using a relatively volatile organic solvent such as toluene and xylene, which is mainly used for highly functional organic materials, is used. There is a problem that the solid content of the ink in 703 is gradually increased, and the film thickness of the formed organic film layer is also gradually increased.

  Furthermore, since the ink used for the high-performance material is a dispersion of an organic polymer material and is expensive, it is desirable to print with a minimum amount of ink. For this reason, since the total amount of highly functional material ink during printing is small, the change in the solid content ratio with respect to the decrease in the solvent due to evaporation is large, which greatly affects the film thickness.

  For example, when the organic EL material A is dissolved in the solvent B and printed, the viscosity increases by 1 mPa · s due to a change in the solid content ratio of 0.02% by weight. An increase in thickness is observed.

  In the organic EL organic film molding, if the film thickness difference is 10 nm or more in the printing surface, it causes a light emission failure. When converted to a solid content ratio, an increase of 0.08% by weight causes a film thickness difference of 10 nm or more, resulting in poor printing. Therefore, in the functional organic polymer material, the solid content ratio in the ink solution is required to be very severely controlled.

  In order to solve the above problem, there has been proposed a method in which the amount of evaporation from the ink chamber 703 is calculated from the viscosity value, replenished and mixed (Patent Document 3).

  However, with this method, it is possible to maintain the film thickness by keeping the viscosity constant, or to reduce the film thickness, but as a method of increasing the film thickness to the target viscosity, the ink material is replenished. Alternatively, the method of adjusting the solid content ratio after waiting for the ink to spontaneously evaporate was the main method.

  If the ink material is replenished, the amount of ink increases and the cost increases, and there is a problem that it takes time to wait for the ink to spontaneously evaporate, resulting in a decrease in printing efficiency. In particular, highly functional materials are expensive and it is desirable to minimize the amount used, so an increase in the amount of liquid is not desirable.

JP 2001-93668 A JP 2001-155858 A JP 2009-81107 A

  In view of the above problems, in the present invention, when printing a highly functional material using a volatile solvent, the viscosity increase is set without replenishing the ink raw material when changing the film thickness by changing the printing setup. It is an object of the present invention to provide a relief printing apparatus that can quickly perform the process up to the value.

  In addition, when promoting the evaporation of volatile solvents to increase the viscosity, we provide a relief printing device that can prevent the deterioration of high-performance organic materials due to the temperature increase in order to accelerate the evaporation without increasing the ink temperature. The task is to do.

The invention described in claim 1 of the present invention
A letterpress printing apparatus for printing a pattern on a substrate to be printed using a letterpress as a printing plate,
A plate cylinder, a substrate surface plate, an ink supply device, and an ink viscosity control unit;
A plate cylinder is a cylinder having on its surface a relief plate having a transfer pattern formed on its surface,
The substrate surface plate is a surface plate on which the substrate to be printed is placed,
The ink supply device is means for supplying ink to the relief printing plate, and includes an ink chamber for storing ink,
The ink viscosity control unit includes an ink viscosity control tank that controls the ink viscosity, an ink viscosity measuring unit, an ink temperature control unit, an air supply unit, and an air exhaust unit.
The ink viscosity measuring means and the ink temperature measuring means are means for measuring the viscosity and temperature of the ink in the ink viscosity control tank, respectively.
The air supply means and the air exhaust means supply clean dry air into the ink viscosity control tank or control the ink viscosity when the viscosity value at the reference temperature calculated from the measured viscosity and the measured temperature is less than the set value, respectively. By exhausting the air containing the ink solvent in the tank and promoting the evaporation of the ink solvent, it is a means to increase the ink viscosity,
The relief printing apparatus is characterized in that the ink viscosity in the ink supply device is controlled by circulating ink between the ink supply device and the ink viscosity control tank.

The invention described in claim 2
The air supply means provided in the ink viscosity control tank supplies clean dry air to the ink viscosity control unit, and the air supply air volume is controlled by a regulator and a flow control valve. It is a relief printing apparatus of description.

The invention according to claim 3
The said air exhaust means provided in the said ink viscosity control tank has a means to exhaust the air containing the ink solvent of an ink viscosity control part, and also to cool exhaust air. This is a relief printing apparatus.

The invention according to claim 4
The supply port for supplying ink to the ink chamber of the ink supply device is provided at the center in the width direction of the ink chamber, and the recovery ports for collecting ink are provided at both ends in the width direction. It is a relief printing apparatus in any one of 1-3.

The invention described in claim 5
5. The air supply means provided in the ink viscosity control tank is installed at the center of the upper part of the ink viscosity control tank, and the exhaust means is installed at both ends of the upper part of the ink viscosity control tank. A relief printing apparatus according to any one of the above.

The invention described in claim 6
The relief printing apparatus according to any one of claims 1 to 5, wherein the ink viscosity control tank has an ink supply port at a central portion in a width direction and an ink recovery port at both ends in the width direction. .

  According to the relief printing apparatus of the present invention, when the viscosity is increased at the time of changeover to increase the film thickness, it is possible to further volatilize without adding an ink raw material and increasing the ink temperature as in the prior art. The evaporation of the organic solvent can promote evaporation rather than spontaneous evaporation. As a result, since a small amount of ink raw material is required, the cost is low, the deterioration due to the heat rise of the ink is prevented, the setup change can be performed in a short time, and printing with a stable film thickness becomes possible.

FIG. 6 is a diagram illustrating an example of a conventional printing apparatus. The figure which shows the printing apparatus using the doctor roll 710 instead of the doctor blade 705. FIG. The figure which shows the relationship of the general property of ink, and is a figure which shows the relationship between solid content ratio and a viscosity. The figure which shows schematic structure of the relief printing apparatus of this invention. The figure which shows the ink viscosity control part 200 which concerns on this invention in detail. FIG. 4 is a diagram illustrating the flow of ink in the ink chamber. The figure which shows the position and width | variety of the deep groove 211 of the ink chamber 108 which concerns on this invention in a cross section. The figure which shows the flow of the ink on the anilox scraped off by the doctor roll. The figure which shows the relationship between the amount of evaporation of an ink solvent, and a viscosity. A top view showing a connection place between the air supply means 300 and the exhaust means 400; The figure which shows the evaporation rate with respect to the amount of exhaust air which used xylene, anisole, and tetralin as an example.

  Details of the relief printing apparatus according to the embodiment of the present invention will be described below with reference to the drawings. However, it should be noted that the drawings are schematic and the dimensions and ratios of the members are different.

  FIG. 4 is a diagram showing a schematic configuration of the relief printing apparatus of the present invention. The relief printing apparatus of the present invention shown in FIG. 4 includes a plate cylinder 105, a substrate surface plate 106, an ink supply device 100, and an ink viscosity control unit 200.

The plate cylinder 105 is a cylinder having a relief plate 103 having a transfer pattern formed on the surface thereof on the peripheral surface.
The substrate surface plate 106 is a surface plate on which the substrate to be printed 107 is placed.
The ink supply device 100 is means for supplying ink to the relief plate 103, and includes an ink chamber 108 for storing ink, an anilox roll 101, and a doctor roll 102.
The anilox roll 101 scoops up ink from the ink chamber 108, and excess ink is scraped off by the doctor roll 102. The ink remaining on the surface of the anilox roll 101 is supplied to the relief plate 103. Reference numeral 104 denotes ink transferred to the relief plate 103.

  FIG. 5 is a diagram showing in detail the ink viscosity control unit 200 according to the present invention. The ink viscosity control unit 200 has an ink viscosity control tank 201, and circulates the ink whose viscosity is controlled between the ink supply apparatus 100 and the ink viscosity control tank 201. As a result, the ink viscosity in the ink supply apparatus is controlled. The

  The ink viscosity control tank 201 is provided with an ink viscosity measuring means 205, an ink temperature measuring means 202, an ink temperature control means 206, an air supply means 300, and an air exhaust means 400. By these means, The ink viscosity is controlled.

  The ink whose viscosity is controlled by the ink viscosity control tank 201 is sent to the ink chamber 108 by the circulation pump 203 through the foreign matter processing filter 204. The ink in the ink chamber 108 overflows and returns to the ink viscosity control tank 201. Alternatively, a pump (not shown) may be provided between the ink chamber 108 and the ink viscosity control tank 201 and returned.

  The air supply means 300 is a means for supplying clean dry air (CDA), and includes a CDA supply source 301, a regulator 302, a supply switching valve 303, and a flow rate control valve 304, and is supplied to the ink viscosity control tank 201. CDA is supplied.

The air exhaust means 400 includes an exhaust switching valve 403, a cooling device 402, and a chemical filter 401. The exhaust air 404 is finally exhausted outside the facility (released to the outside air). The air containing the ink solvent is cooled by the cooling device 402 to liquefy the solvent to form the diluent 207, and when the ink viscosity is controlled, the air is again sent to the ink viscosity control tank 201 by the liquid feeding pump 208.

  The ink viscosity measuring means 205 is preferably capable of measuring the viscosity without changing the liquid state, and examples thereof include a rotary viscometer, a vibration viscometer, a ball drop viscometer, and the like. In particular, since ink is close to Newtonian fluid, it is desirable that the ink has little influence from the outside, or a viscosity measuring device with stable measurement values even with non-Newtonian fluid.

  Moreover, since the viscosity value generally changes with changes in temperature, it is necessary to measure and manage the temperature. For example, when the temperature of an organic light emitting material obtained by dissolving the organic EL material A in an anisole solvent is increased by 1 ° C., the viscosity is decreased by 0.8 mPa · s. As the temperature changes in this way, the intermolecular force of the ink solvent changes, greatly affecting the ink viscosity. Therefore, when the film thickness is controlled by the viscosity value, management for keeping the temperature constant is performed.

  The ink temperature measuring unit 206 is desirably provided at a position close to the position of the ink viscosity measuring unit 205. Further, the ink temperature control means 202 that keeps the temperature constant may be heat radiation using a heat sink and a cooling fan, air cooling, water cooling, or temperature control means using a Peltier element.

  As an anilox roll 101 that can be used in the relief printing apparatus of the present invention, a chromium oxide film formed by plasma spraying chromium oxide on a core roll made of a stainless steel (hereinafter referred to as SUS) material, Either a ceramic roll patterned by laser engraving or a chromium roll with copper plating on the core roll and then applying a resin, laser patterning and then corrosion treatment, and the resulting pattern with chrome plating Can be used. Any pattern such as a helical pattern, FM pattern, honeycomb pattern, diamond pattern, or dot pattern can be used as the pattern formed on the anilocle roll.

  Next, as the doctor roll 102, a core roll made of SUS material, etc., nitrile rubber, silicone rubber, isoprene rubber, styrene butadiene rubber, butadiene rubber, chloroprene rubber, butyl rubber, acrylonitrile rubber, ethylene propylene rubber, urethane rubber, etc. May be prepared by winding a PFA heat shrinkable tube on these rubber rollers. These rubber materials are selected from the resistance to the solvent used as the ink.

  Examples of the solvent for dissolving the functional organic material include toluene, xylene, acetone, anisole, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, tetralin and the like alone or a mixed solvent thereof. Of these, aromatic organic solvents such as toluene, xylene, anisole and tetralin are preferred from the viewpoint of solubility of the functional organic material.

  In order to prevent the solvent volatilization, the ink is supplied to an ink fountain having a closed structure called a closed chamber, and the anilox roll 101 exposed from the closed chamber is rotated while being immersed in the lower peripheral surface of the anilox roll 101. A method of scraping excess ink with a doctor roll 102 and applying ink onto the relief plate 103 can be used.

Excess ink on the anilox roll 101 can be removed using a doctor blade instead of the doctor roll 102, but the doctor blade is generally made of a metal oxide or resin, and is made of an organic semiconductor thin film or organic In the printing for electronic members for the purpose of fine patterning of a functional thin film represented by an EL thin film or the like, a defective product is caused by a scraped foreign matter. In particular, when the foreign material is a metal, problems such as short-circuiting occur due to electrical conduction. For this reason, a doctor roll 102 that does not generate metal foreign matters due to wear in fine patterning of a functional organic material is generally employed.

  The ink viscosity control unit 200 will be described.

  The flow of ink from the ink chamber 108 to the ink viscosity control unit 200 will be described. The ink in the ink chamber 108 is recovered by the ink viscosity control tank 201 when the ink whose viscosity is controlled by the operation of the circulation pump 203 is sent to the ink chamber 108. The viscosity measurement unit 205 and the ink temperature measurement unit 202 in the ink viscosity control tank 201 perform viscosity measurement and temperature measurement, and the viscosity value at the reference temperature is obtained from the result. The determined viscosity value is fed back.

(When increasing viscosity)
When the obtained viscosity value is less than the set value, a signal is issued from the ink viscosity measuring means 205, the air supply means 300 and the air exhaust means 400 are operated, and the air supply means 300 causes the CDA to be stored in the ink viscosity control tank. On the other hand, air inside the ink viscosity control tank 201 is discharged by the air exhaust means 400. In this way, the evaporation of the ink solvent is promoted and the viscosity is increased to a set value.

  In this way, by quickly increasing the ink viscosity in the ink viscosity control tank 201 by promoting the evaporation of the ink solvent component, it is possible to quickly control the set viscosity. Further, when the ink viscosity is controlled in the ink viscosity control tank 201, uniform control can be performed in the entire circulation path by using a stirring operation together.

(When reducing viscosity)
On the contrary, when the viscosity exceeds the set value, the liquid feeding pump 208 is operated and a small amount of the diluent 207 is continuously added to lower the ink viscosity.

  The above operation for increasing the viscosity is performed when changing the film thickness to be formed by increasing the ink viscosity at the time of setup change or the like, and promotes the evaporation of the ink solvent in the ink viscosity control tank 201. The ink viscosity is rapidly increased. Furthermore, the operation of supplying ink to the ink chamber 108 by the circulation pump 203 and the operation of collecting the ink in the ink chamber 108 to the ink viscosity control tank 201 are performed to rapidly increase the viscosity of the ink in the ink chamber 108. Is. In this case, the solid content ratio and viscosity of the ink in the ink circulation system can be shortened by replenishing a small amount of the diluent 207 at a set time interval or continuously at a position slightly exceeding the preset viscosity value. It becomes possible to control by time.

  When performing an air exhaust operation inside the ink viscosity control tank, the air supply means 300 and the air exhaust means 400 perform air supply and exhaust control according to the type of ink. Further, although the evaporation rate varies depending on the amount of ink, it is required to secure an ink surface area corresponding to the amount of ink in the ink viscosity control tank 201. Further, when the viscosity rises to the set value, the evaporation inside the tank is suppressed by stopping the air supply means 300. A needle valve, an air operated valve, or the like can be used as the flow control valve 304 for air volume control in the air supply means 300.

The volatile solvent discharged by the air exhaust means 400 is cooled by the cooling device 402 and returned to the liquid, and is recovered as the diluent 207. The cooling device 402 may be a device using a Peltier element or a device using water cooling.

  As the air supply switching valve 303 for controlling the operation and stop of the air supply means 300 and the exhaust switching valve 403 of the air exhaust means 400, valves such as an air operated valve and an electromagnetic valve can be used.

  The circulation amount of the circulation pump 203 that circulates ink preferably corresponds to at least the amount of ink required for the circulation flow rate per minute. If the required ink amount is not clear, it is preferable to circulate the same amount of ink as the volume of the ink chamber 108 per minute. However, if a pump with a large amount of circulating fluid is used, the temperature change accompanying the heat generation of the motor and the increase of the fluid pressure becomes large, which greatly affects the viscosity. Therefore, as the circulation pump 203, an air-driven diaphragm pump or a small motor-type diaphragm pump that has little influence on heat is suitable. In addition, a diaphragm pump is preferable from the viewpoint that there is no rubbing or contact of the operation part during the liquid feeding operation due to mixing of foreign substances in the high-functional material.

  FIG. 6 shows the flow of ink in the ink chamber 108. A deep groove 211 is dug from the ink supply port 209 of the ink chamber 108 to the ink recovery port 210. The ink injected from the central ink supply port 209 of the ink chamber 108 by the deep groove 211 flows along the deep groove 211 toward the ink recovery port 210. By constantly supplying and collecting ink, the solid content concentration in the ink chamber 108 can be made uniform.

  FIG. 7 is a cross-sectional view showing the position and width of the deep groove 211 of the ink chamber 108. The shape of the deep groove 211 is required to cause the supplied ink to spread through the groove and the anilox roll 101 by capillary action. Therefore, it is desirable that the supply port, the recovery port, and the deep groove of the ink chamber 108 are located closest to the anilox roll 101. The width of the groove of the ink chamber 108 is a position where a vertical line is dropped from a position of 1 ° or more and less than 20 ° to the left and right from a line straight line connecting the anilox roll 101 and the closest portion of the chamber to the axis of the anilox roll. Width. The depth of the deep groove is required to flow laterally before the ink coming out from the supply port contacts the aniloc roll, and since the amount of ink accumulated in the groove is required to be small, The volume is desirably 2% to 10%.

The flow of ink on the anilox scraped off by the doctor roll 102 is shown in FIG.
The ink on the anilox roll 101 scraped by the doctor roll 102 is collected at the contact point between the anilox roll 101 and the doctor roll 102 and gradually flows toward the end of the anilox roll 101 as indicated by an arrow 212. The ink collecting port 210 is installed at the end of the ink chamber 108 because the ink finally collects at the end of the ink chamber 108. Further, since the ink supply to the ink supply port 209 is always performed, the ink chamber 108 having the above structure increases the fluidity of the ink in the ink chamber 108 and keeps the solid content concentration in the ink chamber uniform. It is possible.

  The control of the supply of CDA and the exhaust of the air containing the ink solvent is performed by outputting the viscosity value measured by the ink viscosity measuring means 206 installed in the ink viscosity control tank 201 to the outside, and the content of the ink solvent in the circulation system. The air supply means 300 and the air exhaust means 400 for promoting evaporation of the CDA supply and ink solvent based on a program prepared in advance by feeding back the measured viscosity value to a preset viscosity value inputted in advance. The exhaust control of the air containing is performed by a computer.

  Examples of the present invention will be described below. In addition, this invention is not limited to an Example, The improvement, deformation | transformation, etc. in the range which can achieve this invention do not deviate from the meaning of this invention.

<Example 1>
Examples of the present invention will be specifically described below.
In Example 1, viscosity adjustment for viscosity increase was performed using 100 ml of organic EL ink in which an organic light emitting material was dissolved in solvent A. The relationship between the evaporation amount of the ink solvent and the viscosity is shown in FIG. Moreover, the relief printing apparatus used has the ink supply means having the configuration and function described in the above embodiment, and a relief printing apparatus that prints on a flat substrate such as a glass substrate with a sheet of paper. In the evaluation method, the time for changing the ink viscosity from about 60 mPa · s to about 64 mPa · s as a set value by changing the solid content ratio of the ink is defined as the viscosity control time, and increases with the completion of circulation of 100 ml of organic EL ink. An evaluation was made as to whether viscosity was possible.

  As the air supply means 300 for exhausting the inside of the ink viscosity control tank 201, a flow rate control valve 304 capable of controlling the amount of air supplied into the ink viscosity control tank to 30 to 50 L / min was used. FIG. 10 is a top view showing a place where the air supply means 300 and the exhaust means 400 are connected. The connection place of the air supply means 300 is the central part 214 in the width direction of the upper part of the ink viscosity control tank 201. Similarly, the connection part of the exhaust means 400 is two places at both ends in the width direction of the upper part of the ink viscosity control tank 201. 215a-d, and the CDA was distributed over the entire ink surface of the ink viscosity control tank 201.

Regarding the ink viscosity control unit 200, the ink chamber 108 has ink recovery ports 210 at both ends in the longitudinal direction (width direction), an ink supply port 209 at the center, and the ink supply port 209 and the ink recovery port 210 are connected by a deep groove. A diaphragm type pump having a flow rate of 0.1 to 0.2 L / min is defined as a circulation pump 203 with a condition that the circulation of the organic EL ink is completed at a rate of 100 ml in 1 min. used.
<Ink viscosity measuring means>
As the ink viscosity measuring means 205, an in-line torsional vibration type viscometer having no self-heating and excellent in high-accuracy responsiveness was used. As the ink temperature control means 202, a cooling method by heat radiation by a jig using a copper plate, a heat sink and a cooling fan was used.

The air flow rate of the air exhaust means 400 when increasing the viscosity is set from the graph of the evaporation rate with respect to the exhaust air flow rate in FIG. Since it is desirable that the set value of the air volume does not affect the ink liquid level, it is set to 0.4 m ³ / min as a value that does not cause undulation. The amount of evaporation required to increase the viscosity from about 60 mPa · s to about 64 mPa · s is about 7.1 ml from the graph of the amount of evaporation and viscosity in FIG.

Air volume and evaporation rate as a set value of ink viscosity control tank surface area for evaporating 7.1 ml of the ink solvent in 1 min, which is the time for 100 ml of organic EL ink to circulate in the circulation path. Based on the curve relating to anisole in FIG. 11 showing the relationship of FIG. 11, the surface of the ink viscosity control tank is provided with a surface area of 30 cm ² for the ink to come into contact with air. When the ink viscosity in the viscosity control tank 201 exceeds the set value, the air supply switching valve 303 of the air supply unit 300 and the exhaust switching valve 403 of the air exhaust unit 400 are closed at the same time, and the diluent replenishing unit 207 is activated. Thus, the automatic viscosity control of the ink was performed.

By setting the ink viscosity control conditions as described above, the viscosity rapidly increases to the set viscosity, reaches the set viscosity of 64 mPa · s in about 1 min, stops the air supply means 300 and the air exhaust means 400, and dilutes. By starting the replenishment of the liquid, the viscosity inside the ink viscosity control tank could be controlled to about 64 mPa · s.

<Comparative example>
In the comparative example, the time to increase to the target viscosity was measured only by the ink circulation operation without using the ink viscosity control tank 201 under the same conditions as in Example 1. While the viscosity of the ink inside the ink viscosity control tank during viscosity control was increased due to natural evaporation, it took about 1 hour.

  From the above results, according to the ink viscosity control unit 200 according to the present invention, it is possible to significantly reduce the time to increase to the target viscosity.

  The relief printing apparatus according to the present embodiment includes, for example, a pattern in a color filter for a liquid crystal display (LCD), a light emitting layer and a charge transport layer of an organic electroluminescence (EL) element, an electrode pattern in an organic thin film transistor (TFT) substrate, It can be used to form a high-definition pattern such as a shield pattern in an electromagnetic wave shield.

  As described above, according to the relief printing apparatus of the present invention, particularly at the time of setup change requiring an increase in viscosity when the film thickness is increased, it is possible to quickly reach the set viscosity value without adding an ink raw material as in the prior art. It becomes possible to adjust to. As a result, it is possible to quickly change the setup at low cost, and it is possible to print with a stable film thickness.

DESCRIPTION OF SYMBOLS 100 ... Ink supply apparatus 101 ... Anilox roll 102 ... Doctor roll 103 ... Letterpress 104 ... Ink transferred to letterpress 103 105 ... Plate cylinder 106 ... Substrate surface plate 107- ..Printed substrate 108 ... Ink chamber 100 ... Ink supply device 200 ... Ink viscosity controller 201 ... Ink viscosity control tank 202 ... Ink temperature measuring means 203 ... Circulating pump 204- .... Foreign matter processing filter 205 ... Ink viscosity measuring means 206 ... Ink temperature control means 207 ... Diluent 208 ... Liquid feed pump 300 ... Air (CDA) supply means 301 ... CAD supply Source 302 ... Regulator 303 ... Supply switching valve 304 ... Flow control valve 400 ... Air exhaust means 40 ... chemical filter 402 ... cooling device 403 ... exhaust switching valve 404 ... exhaust air 701 ... Toppan (resin relief plate)
702 ... Plate cylinder 703 ... Ink chamber 704 ... Anilox roll 705 ... Doctor blade 706 ... Substrate 707 ... Substrate surface plate 708 ... Movement direction of substrate surface plate 709 ..Rotating direction of plate cylinder 710 ... Doctor roll

Claims (6)

A letterpress printing apparatus for printing a pattern on a substrate to be printed using a letterpress as a printing plate,
A plate cylinder, a substrate surface plate, an ink supply device, and an ink viscosity control unit;
A plate cylinder is a cylinder having on its surface a relief plate having a transfer pattern formed on its surface,
The substrate surface plate is a surface plate on which the substrate to be printed is placed,
The ink supply device is means for supplying ink to the relief printing plate, and includes an ink chamber for storing ink,
The ink viscosity control unit includes an ink viscosity control tank that controls the ink viscosity, an ink viscosity measuring unit, an ink temperature control unit, an air supply unit, and an air exhaust unit.
The ink viscosity measuring means and the ink temperature measuring means are means for measuring the viscosity and temperature of the ink in the ink viscosity control tank, respectively.
The air supply means and the air exhaust means supply clean dry air into the ink viscosity control tank or control the ink viscosity when the viscosity value at the reference temperature calculated from the measured viscosity and the measured temperature is less than the set value, respectively. By exhausting the air containing the ink solvent in the tank and promoting the evaporation of the ink solvent, it is a means to increase the ink viscosity,
A letterpress printing apparatus characterized by controlling ink viscosity in an ink supply device by circulating ink between the ink supply device and an ink viscosity control tank.   The air supply means provided in the ink viscosity control tank supplies clean dry air to the ink viscosity control unit, and the air supply air volume is controlled by a regulator and a flow control valve. The letterpress printing apparatus described.   The said air exhaust means provided in the said ink viscosity control tank has a means to exhaust the air containing the ink solvent of an ink viscosity control part, and also to cool exhaust air. Letterpress printing equipment.   The supply port for supplying ink to the ink chamber of the ink supply device is provided at the center in the width direction of the ink chamber, and the recovery ports for collecting ink are provided at both ends in the width direction. The relief printing apparatus according to any one of 1 to 3.   5. The air supply means provided in the ink viscosity control tank is installed at the center of the upper part of the ink viscosity control tank, and the exhaust means is installed at both ends of the upper part of the ink viscosity control tank. The relief printing apparatus according to any one of the above.   The relief printing apparatus according to any one of claims 1 to 5, wherein the ink viscosity control tank has an ink supply port at a central portion in a width direction and an ink recovery port at both ends in the width direction.

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