KR100700226B1 - Apparatus for printing objects of the tablet type, in particular medical tablets and process therefor - Google Patents

Abstract

A relatively small, lightweight object having a certain brittleness and / or porosity, in particular a tablet-like object, more specifically a medical tablet-type printing object 6, is printed, the movable printhead 25, the printing liquid tank 30 And a conveyor unit (32) for supplying the print object (6) to the print head (25) and discharging it from the print head, wherein the print head (25) has a printing liquid tank (30) Arranged in a linear pad printing system with a closed printing system in which the conveyor unit 32 has a rotation having a predetermined place 24; 24 ', 24 "for temporarily storing the object to be printed 6 during printing. It consists of tables 14 and 17.

Tablet, printing

Description

Apparatus for printing objects of the tablet type, in particular medical tablets and process therefor}

The present invention relates to an apparatus and method for printing on a tablet-like object such as a medical tablet.

Printing trademarks and logos on medical tablets has increased over the years. Pharmaceutical companies want to differentiate themselves from so-called generic drug manufacturers. These generic drugs contain much the same active substance as the original drug but are much cheaper.

Only a few years ago, this marking was carried out by a so-called embossing process, in which the image is stamped into the tablet when the tablet is pressed with a relief coating. The marking was not visually effective since there was no contrast and no contrast with the tablet itself. In addition, the cost of the relief painting itself, replacement cost and adjustment cost were considerable. Thus, the embossing technique has been replaced by printing of clearly identifiable inks.

 There are several techniques for printing medical tablets with ink that is licensed for therapeutic purposes. The most widely used technology at present is the rotary pad printing method.                 

In the rotary pad printing method, the rotating cylinder 1 in which the image to be printed is engraved is used. This cylinder is arranged horizontally, and the bottom surface is enclosed inside the ink cup 2. Ink is scraped off from the cylinder surface with a knife 3 so that only ink remains on the intaglio pattern. Since the pad 4 covered with rubber such as silicone rubber is rotated in contact with the cylinder to collect the remaining ink, the image to be printed is finally obtained from the cylinder.

These pads are then in contact with the tablet to engrave the images. In this printing process, the rotary printing pad and the cliché cylinder must exactly match the tablet to be printed passing through the conveyor system in the direction of the arrow (7).

This rotary pad printing method has some serious drawbacks. The print quality is degraded due to the speed difference between the various parts. In order to improve print quality in the rotary pad printing method, the tablet's speed 10 and the pad's peripheral speed 9 in the tablet conveyor system must match exactly. If there is a difference in these speeds, slippage occurs and adversely affect print quality.

However, the problem is that most medical tablets are not completely cylindrical. The top and bottom of the tablets are somewhat arched. The flexibility of the rubber 5 of the pad solves this problem. The curved portion of the tablet slightly presses the silicon layer. However, since the angular velocity 8 of the pad is constant, the circumferential velocities at the various contact points of the tablet are not equal to the linear movement speed 11 of the tablet. Because of this, there is always a slight slip, which is inherently related to the structure of the tablet itself, deteriorating print quality.

When printing the flat tablet 13 by the rotary pad printing method, the entire upper surface of the tablet may be printed.

When the top and bottom surfaces of the tablet 13 'are curved, it is necessary to press the pad 12 further to the tablet, so as to press the tablet with the silicone rubber of the pad. It is only possible to engrave a print image of a predetermined size on a tablet.

However, if the pressure of the pad applied to the tablet is too large, there is a risk of breaking the tablet 13 ". Therefore, the maximum size of the image to be printed on the tablet is limited.

In addition, the thickness of the ink layer which can be etched into the product by the rotary pad printing method is not so large. Because of this, there is a problem that the printing on a porous tablet that can absorb a large amount of ink. In this case, the print contrast does not appear high. For example, suppose you want to print white ink on a dark porous tablet. In this case, the printed matter by the rotary pad printing method may appear gray instead of white. As a result, the impression is faded.

There is also a risk of contamination of the conveyor system for tablets. In the pharmaceutical field, pollution problems are very important. The contamination may be caused by external contaminants mixed with the tablet, but may also be caused by the tablet remaining in the preproduction process. In general, it is said that as few holes or cavities in the printing apparatus as possible are needed to reduce the possibility of remaining foreign particles.

Tablet conveyor systems for rotary pad printing usually consist of strip chains with holes for picking up tablets. This chain moves along a rotating printhead that squeezes tablets thereon.

In tablet conveyor systems with these chains, there is basically a risk of contamination. Dirt, broken tablets, or even intact tablets may remain between the strips of the chain. The tablet conveyor system between two production batches has the disadvantage that it takes a lot of time to clean.

There is also a risk of fire or explosion when the solvent escapes the ink. Inks used to print medical tablets typically contain solvents made of highly volatile and flammable materials such as propanol, ethanol and butanol.

Most rotary pad printing systems are provided with an open ink tray. By rotating the patterned cylinder in a small ink container, scraping off the excess ink with a knife allows the cylinder to get ink. In small containment chambers, air circulating rooms, or so-called medical cleaning room environments, explosive solvent-air mixtures can be produced very rapidly by evaporation of the solvent from the ink. To avoid this, complicated suction systems are often used, but this can cause problems with print quality due to the formation of strong airflow around the pattern cylinder and the pad cylinder.

In open ink systems, solvent evaporation from the ink not only creates a dangerous solvent / air mixture, but also gradually thickens as the solvent evaporates slowly from the ink in the open ink container. Because of this change in viscosity, the pressure characteristics of the ink also change, resulting in poor print quality.

The solution is to use an expensive viscosity control system that further dilutes the ink by adding thinner. To do this, a viscosity control system and an ink pump are required. The problem with this viscosity control system is that more expensive ink is needed from the outset in order to operate the control system reliably, resulting in an additional task of cleaning itself.

In order to solve the problems described above, according to the present invention provides a linear pad printing apparatus having a rotary table and a closed ink system for moving the tablets in the sections on the plate. According to the present invention, there is provided a printing apparatus including a movable printhead, a printing liquid tank, and a conveyor unit for supplying and discharging print objects from the printhead, respectively. At this time, the print head is disposed in a linear pad printing system having a closed ink system, the printing liquid tank is disposed in a closed ink system, the conveyor unit is composed of a rotating table, and a print object is prescribed during the printing step. Can be taken temporarily in position.

Other features of the invention are as defined in the claims.

Thanks to the system according to the invention, the problems inherent in the conventional rotary pad printing system described above are solved. Hereinafter, various advantages of the present system will be described.

Degradation due to speed difference does not occur in linear pad printing because tablets do not move during printing.

In linear pad printing, the silicone or rubber area of the pad can be made much smoother than rotary pad printing without compromising print quality. Because the pad is softer, the pad can be pressed harder against the tablet without risking damaging the tablet, thus printing a larger print image on the curved tablet. As a result, the maximum print image limit is considerably relaxed.

In linear printing, a much thicker layer of ink can be engraved than in rotary printing. This improves contrast and print quality when printing on porous tablets.

The present invention uses a flat, very smooth abrasive table plate as a whole and moves the tablet through section plates that can be easily removed from the table plate, making cleaning much simpler and better preventing contamination.

All sections can be separated within minutes and then immersed in a wash / decontaminate bath. Next, the smooth table surface on which the tablet slides through each section is conveniently wiped with a decontamination / cleaning agent (eg alcohol). This too can be done in a short time.

Using the closed ink container as described above, the amount of solvent evaporated from the ink is very small. As a result, the explosion risk is also drastically reduced compared to conventional systems such as an open ink system with a scraping knife or the like. A disadvantage of the open system is that the ink is exposed to air in large surface areas. There is also a need for an ink circulation system that can automatically adjust the viscosity of the ink. Without this viscosity control system, the solvent evaporates and the ink typically becomes very quickly useless in tens of minutes. Evaporating solvents also pose a risk of fire or explosion.

An ink used in the pharmaceutical field is thixotrope. It is still difficult to properly maintain the viscosity of the ink. Viscosity control systems can quickly become unstable if mishandled.                 

In order to obtain a stable viscosity control system, a relatively large amount of expensive inks must be used in the ink system.

Because of the complicated ink circulation system requiring viscosity control, cleaning the ink system is a time-consuming and laborious task. Hoses in ink systems are often used disposable to save time.

To change the type or color of the ink, a complete second ink system is required and the machine must be shut down for about 40 minutes. The time taken to clean the first ink system was, of course, not calculated.

In order to solve this problem, it is advantageous to use closed small ink ports. The printing apparatus uses two closed ink containers, usually about 200 ml each. Evaporation of the solvent from the ink is minimized because the small port is closed with a lid. Therefore, not only the ink circulation system is required but also the viscosity control is unnecessary. Depending on the type of ink, the printing device can run for 3-18 hours without adding solvent.

The cleaning of small ink ports is very simple and quick without expensive ink loss.

Another advantage is that it only takes a few minutes to replace the ink and only requires an ink port.

It is also possible to use a vacuum system consisting of a vacuum chamber (also called a vacuum block) and connected to an electric vacuum pump so that the tablet does not stick to the pad during printing. This vacuum block is mounted just below the location where the tablet is printed. Small holes are formed on the top of the block that are blocked by a pen. During the printing operation, the pen is removed from the small hole with a pneumatic cylinder, and the tablets placed thereon are vacuumed. When the print job is finished, close the small holes with a pen to return to the original state.

The serious problem with this is that it is a very complex, vibration-sensitive system and has been developed for only one type of tablet. Every time you need to print a new tablet, you need to replace the entire vacuum block.

In addition, the vacuum block is very expensive because it requires the use of precision components such as a sealing pen or a smooth stainless steel top plate.

The total weight of the vacuum block is about 30 kg, which must be manually disassembled in the middle of the device to replace it. It can be lifted electrically, but replacing it for other types of tablets is still a cumbersome task.

In contrast, according to the present invention, there is provided a vacuum system that adsorbs a tablet during a printing operation but uses an additional vacuum buffer and one vacuum valve, and does not need to block the system with a pen. As a result, it is no longer necessary to replace the entire vacuum block when changing the shape of the tablet. Only the stainless steel top plate in which small holes are formed according to a predetermined pattern suitable for the type of tablet needs to be replaced. This can also be done simply.

Therefore, only one vacuum block is needed, thus reducing the cost. Switching to another type of tablet is also faster and can be done in one person without the need for physical labor.                 

In addition, due to the simple structure, the possibility of failure is considerably reduced. The maturity of the tablet device is also significantly improved. The need for the pharmaceutical industry is also considered significant.

If the production cycle is short with a continuous production cycle of 3-5 hours, no solvent is added to the closed ink system. For long cycles, a simple system of adding a small amount of solvent regularly is sufficient. Thus, a fully automatic viscous system is unnecessary. In this way, a simple system can be obtained.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 to 5 are schematic views of a conventional rotary printing method;

6 is a schematic view of a tablet conveyor system of the apparatus according to the invention;

7 is a top view of the tablet conveyor system of FIG. 6;

8 is a schematic view of a vacuum system of the apparatus according to the invention;

9 and 10 are schematic views of a roll process in linear pad printing, respectively.

11 is a schematic representation of the various stages of the process according to the invention.

As shown in FIG. 6, a very smooth tablet plate 14 is used in a tablet conveyor system. The other parts of the conveyor system for tablets are as flat and smooth as possible, so they can be easily cleaned and decontaminated. Equipped with a section 17 that can be easily disassembled on such a tablet plate 14, it is arranged on the tablet plate 14 spaced several tens of millimeters apart. In these sections 17, a hole 24 into which the tablet 6 can be inserted is formed. When the sections on the tablet plate are moved in the direction of the arrow 18, the tablets 8 are transported. These tablets still lie on a very flat tablet plate 14.

Other methods may be used to feed the tablet into the holes 24 in the section. In this case, a brush casing 21 can be used, which inserts the tablet 6 into all the holes 24 in the section 17. These tablets can be ejected very simply. Tablets that are only transported together with the holes, without being tightly fitted in the holes of the section, fall down through the exit holes 15 of the tablet plate 14. Underneath is the ejector 16, where the tablet 6 falls off and is discharged out of the device.

An embodiment of the present invention with eight sections is shown in FIG. 7. All eight sections 17 are arranged around the axis of the index casing. These sections 17 can be rotated one section by an index casing at the printing position.

The sections 17 rotate clockwise in an indexed manner. The tablets are supplied to the brush system 21 by the supply bunker 20. This brush system fills the tablet in the tablet holes 24 in the section. In this case, there are two circular tablet patterns 24 'and 24 "for each section. The sections filled with the tablet rotate while passing through a blower such as the air knife 22, and the compressed container of the air knife Waste tablets or dust are blown to 23. Finally, each section passes under the linear print head 25. The printed tablets pass through the drying section 26 and then are discharged by the ejector 27.

9 and 10 illustrate a method of rolling a pad against a tablet without slipping during printing.

When you press the printed image of the pad against the tablet, the tablet may stick to the pad because the tablet is light and sticky. To prevent this, a vacuum chamber is arranged at the printing position, ie under the tablet plate 14 just under the print head. As shown in FIG. 8, this vacuum chamber adsorbs the tablet 6 during the printing operation through the small holes 39 of the tablet plate 14. Except when the tablet is in motion, the necessary vacuum can be formed with an electric vacuum pump together with a vacuum valve controlled to generate a vacuum under the tablet only when the printing operation is effective. The vacuum block is advantageous because it does not need to be replaced except for the upper plate.

The print head 25 is a linear pad printing type having a closed ink container. The operation is shown in side view in FIG. 11, in which a section 32 having a closed ink tank 30, a pad 31, a cliche 33 and a tablet is represented. The tablet conveyor system operates as indicated by the cross sectional view of FIG. 11.

A is the starting position. The pad 31 is vertically downward in the direction of the arrow F1 to take ink in the cliché 33. After taking ink at B, the pad returns to the A position. In C, the pad on which the image is transferred is advanced in the direction of arrow G1 and moved over the tablet to be printed in section 32. At the same time, the ink tank 30 slides forward to bury ink in the recesses of the cliché 33. The pad 31 descends from the D position to engrave the image transferred to the tablet, and then rises back to the C position. Subsequently, the pad 31 returns to the start position A and the closed ink tank 30 also returns to the start position.

Ink tanks or closed small ink ports have been described in European patent application EP96200793.6, the contents of which have been described only by reference in the present application. It should be understood that the above-described operation is only an example and does not limit the scope of the present invention.

Claims (11)

A printing device for printing on a relatively small lightweight object including a medical tablet 6 having a predetermined brittleness or porosity, and prints the movable print head 25, the printing liquid tank 30, and the object to be printed 6 A conveyor unit 32 for supplying to the head 25 and ejecting from the print head, The printhead 25 is arranged in a linear pad printing system with a closed printing system in which a printing liquid tank 30 is disposed; The conveyor unit 32 is constituted by rotating tables 14 and 17 having predetermined places (holes, 24; 24 ', 24 ") for temporarily storing the object to be printed 6 during printing. Printing device. 2. The rotating table according to claim 1, wherein the rotary table comprises a very smooth table plate (14) and a plurality of sections (17) spaced apart from the table plate (14) by a predetermined distance (38), wherein the table plate and sections are flat. Printing apparatus, characterized in that. 3. The holes 17 according to claim 2, wherein holes 24 for inserting and ejecting a print object are formed in the sections 17 so that the bottom surface of the print object 6 contacts the table plate 14. There is a printing apparatus. The method of claim 2, wherein the sections 17 are movable and interchangeable, so that the sections 17 may include holes 24 having different shapes and sizes for the object to be printed. And a predetermined pattern (24 ', 24 ") arranged in the section (17). The printing apparatus according to claim 2, wherein the sections (17) constitute a disc, and are adjacent to each other and separated in a radial direction. 3. The brush according to claim 2, further comprising: a supply unit (20) for storing the printing object (6) to be supplied to the rotary table, and a plurality of brushes disposed in the discharge holes of the supply unit (20) and movable downwards. Is provided in the brush casing (21), wherein the brush functions as an object separator on the section (17) to completely eject the object to be printed from the hole (24). 7. A printing apparatus according to claim 6, wherein a blowing unit (22) is arranged downstream of said brush casing (21) for blowing out the wastes to said storage unit (23). 3. A printing apparatus according to claim 2, wherein a drying section (26) is arranged on the downstream side of the linear print head to dry the object to be printed. 3. The rotary table 14 of claim 2, wherein the vacuum chamber 28 for adsorbing the printing object 6 during the printing operation through the small holes 39 of the table plate 14 is placed. 17) A printing apparatus, characterized in that it is disposed below. 10. A printing apparatus according to claim 9, wherein the vacuum chamber is arranged around each of the corresponding holes (24) for the printing object (6). A method of printing on a medical tablet by the device according to any one of the preceding claims: The pad print head 31 is moved downward from the start position A, and a predetermined amount of printing liquid such as ink is collected from the cliché plate 33 at the ink collecting position B, and then the pad print head loaded with ink ( After 31 is raised to the initial position A, the printhead 31 from which the image is taken is advanced until it is on the medical tablet 6 to be printed in the section 17, and the ink tank 30 is also in the same direction. The ink on the image of the cliché plate, and then the printhead descends to the tablet and attaches the collected image to the print object, and then the printhead is moved to the initial position (A) together with the ink tank 30. A printing method characterized by returning.

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