JPH0127840B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for producing molded articles in the field of medicine, food or catalyst industry, in which a lubricant in the form of a liquid or a suspension is produced in separate droplets in a molding machine, for example a tablet press. Regarding the method of intermittent scattering.

German patent application No. P27 17 438.5 is characterized in that a dissolved or molten release agent is applied to the walls of the compression chamber before each compression operation by means of a nozzle system that can be sprayed briefly (intermittently) at rapid intervals. A method for covering the compression chamber of a tablet press is described.

However, with newer high speed tablet presses, hydraulically operated spray systems are too slow to coat the forming equipment before each compression operation. In principle, however, it is desirable that the amount of lubricant be as low as possible (in order to achieve optimum bioavailability, formability and clear and rapid dissolution, for example for diagnostic or effervescent tablets). Spray systems therefore include applying the required amount of lubricant concentratedly to the highly loaded areas of the compression device (e.g. the compression area in the bore), in the shortest possible time (e.g. within a few milliseconds), and intermittently. The ability to apply specific and direct applications is required.

It has now been found that these requirements can be met in an excellent manner. The method uses a piezoelectric transducer, using geometrically arranged nozzles, or by electrostatically or electromagnetically deflecting the path of the droplets, before each compression operation. A specific amount of lubricant in liquid or suspension form, and as discrete droplets of a certain specific volume, is applied to the area under pressure of the compression device, directionally, within a few milliseconds, at a defined velocity. It is a method of depositing.

The spot application of the droplets is carried out intermittently, for example with a tubular or flat piezoelectric transducer, before each compression operation. This piezoelectric transducer generates a motive force for a liquid or suspension.

Suitable systems for point-wise application of liquid or suspended lubricants as droplets include, for example, an array of interlocking conduit sections, with a tubular piezoelectric oscillator concentrically extending the cross-section of each conduit section. We can list systems that are surrounded by The electrodes used to provide the signal are conductive plates, for example silver plates, placed on the surface of the tubular piezoelectric oscillator.

The outlet opening of the conduit is arranged so that droplets of lubricant are applied point-wise to a certain area of the forming device through it. On its supply side, each conduit is connected, for example, to a common distribution plate, which connects to a supply container from which liquid or suspension lubricant is supplied (see FIG. 1).

A backflow of liquid or suspension in the nozzle conduit can be prevented, for example, by the nozzle conduit tapering towards the outlet opening. Due to the nature of the piezoelectric oscillator to undergo elastic deformation upon application of certain electric fields, a shock wave is generated in the tubular piezoelectric oscillator towards the liquid. The synchronized pressure increase causes a very small amount of lubricant to be ejected from the outlet opening in the form of lobes. It is believed that the lubricant flakes assume a spherical shape after leaving the exit opening. Advantageously, the diameter of the conduit is approximately 1 mm in the central part, and the individual conduit tapers at its outlet opening. The diameter of the outlet opening is, for example, 0.1 mm.

The supply is located lower than the outlet opening, and this relationship creates a vacuum in the system. The height difference creates a static vacuum within the conduit, which, in combination with capillary action, causes instantaneous overcompensation within the conduit to which an electric field is applied.

Capillary action within the conduit and at the outlet opening prevents backflow of the lubricant liquid or suspension.

That is, for example, 3000 droplets exit the aperture with a droplet firing frequency of 3KHz and a lubricant viscosity of approximately 20 mpas. The droplet velocity is approximately 4 m/s, resulting in droplets of very constant weight, approximately 0.8 μg (0.0008 mg).
Electrically adjustable droplet firing frequency from a few hundred hertz
Although it can be up to 50KHz, it is preferably around 3KHz. Excitation of the piezoelectric oscillator is performed, for example, with an electrical pulse of 120 V and a pulse duration of 20 milliseconds.

The conduit surrounding the piezoelectric oscillator may be bent at the front or rear of the oscillator as appropriate. This embodiment provides better adaptation to space conditions, such as tablet presses. However, it is also possible to branch the conduit into two or more conduits at the rear position of the piezoelectric oscillator, so that one piezoelectric oscillator acts on several conduits leading to separate outlet openings. . The outlet opening may be a hole in a glass or metal plate, for example. If the conduit is comprised of a glass capillary tube, the outlet opening may be formed by pulling out the end of the glass tube.

Other advantageous embodiments for point-wise application of liquid or suspension lubricants as droplets include the use of plate-type planar transducers operating on piezoelectric principles, which are preferred. The bars are fitted concentrically at the top of the conduit inlet. Again, a tapered outlet opening is provided at the end of the conduit. In a preferred embodiment, the piezoelectric plate is placed horizontally and concentrically with respect to the longitudinal conduit. A piezoelectric plate is placed in or on the chamber to receive the lubricant liquid or suspension. Several conduits exit from a common chamber, which in turn connects to a common liquid supply. That is, one plate-like oscillator (piezoelectric plate) simultaneously generates pressure waves in several conduits connected to the same distribution chamber.

Furthermore, in an advantageous embodiment of simplified construction, a plate-like oscillator producing a powerful impulse is placed in a distribution chamber, and a number of conduits of various types and in an arbitrary arrangement are arranged at intervals from this chamber at its end. Connect to multiple nozzles. With such an arrangement, point application of a droplet to the surface from a single impact generated by the piezo oscillator can be achieved (see FIGS. 2a, 2b, 2c).

In the case of high-speed tablet presses, both the upper and lower punches that fit into the holes pass in front of the dot application system of droplets in a few milliseconds. However, a conduit operating at a droplet firing frequency of several KHz can deliver not just one but a series of lubricant droplets during this time. By suitable adjustment of the droplet spot application system consisting of a number of conduits with outlet openings, or by their geometrical arrangement, such that when the forming device arrives, all the conduits spray simultaneously. You can take the method of spraying in time. It is also possible to select the droplet firing frequency of the conduit differently depending on the area of the forming device to which the droplets are applied point-wise. It is thus possible to directly apply more lubricant to certain areas of the forming device (for example, the holes or the compressed areas of the upper or lower punch engravings) than to areas that are less loaded. Furthermore, it is possible to vary the type of lubricant solution supplied by a conduit that applies droplets in spots on the hole wall and in a conduit that applies droplets in spots on the surface of the punch.

To focus droplets generated by a piezoelectric transducer onto the desired surface of a forming device, the droplets are often charged by applying a voltage after they leave the exit aperture, and then charged. Advantageously, the path is adjusted by electrostatic deflection. This adjustment can be carried out in a conventional manner, for example according to the principle of anode beam deflection in a cathode ray tube.

Piezoracemic bodies can also be used as valves, provided that the lubricant liquid or suspension is supplied under pressure to an oscillator or transducer that opens and closes as desired. For example, a slit-shaped opening may be momentarily opened in a conduit containing a liquid under pressure, and the filling material may be transported through this opening in the form of droplets. This opening may be provided in the oscillator itself, blocking off the space under pressure, as a valve, or it may be provided in a gap between the oscillator and the material forming the conduit wall. This operation can also be performed in reverse, and a method may be chosen in which the oscillator blocks off the space under pressure.

However, in the case of high-pressure tablet presses, it is also advantageous for the individual lubricant droplets to be accelerated by an air stream on the way to the forming device in which they are applied. The air stream can be easily extracted from, for example, a contact control nozzle connected to compressed air.

This droplet spot application system can be adapted to any pre-fill and post-discharge position of the tablet press. However, it is particularly suitable for the spray opening of the spray system to be located approximately 1 mm above the dial where the hole is located. It is therefore possible to apply a drop directly from above into the cup formed by the hole wall and the active surface of the lower punch. It is also possible to apply droplets directly to the gap between the hole and the lower punch.

Regulating signals for intermittent and precise droplet application include, for example, photocells or inductive or capacitive contact switches.

In addition to lubricant solutions and suspensions, molten lubricants can also be used by heating to an appropriate temperature using a heating plate with a built-in distribution section. By heating the supply container section and the conduit section, the lubricant can be transported to the spray section.

The liquid lubricant can advantageously be conveyed to the conduit via a suitable compact filter.

Figures 1 to 4 schematically and exemplarily show several devices that can be used to apply liquid or suspension lubricants as droplets to molding devices.

FIG. 1 shows a schematic cross-section of a droplet point application system, in which each piezoelectric transducer 1 surrounds one nozzle conduit 8, the end of which is connected to a capillary section 7. is formed.
Each capillary section 7 is present in a corresponding opening in the outlet nozzle plate 6, so that from the nozzle formed by the capillary section 7 and the opening in the outlet plate 6, a droplet of liquid 5 is fired. The nozzle conduit 8 connects to the liquid chamber 2 through a narrow liquid passage 9. This distribution chamber 2 has a drainage groove 10 and is connected to a liquid supply 3 through a passage plate 4 . Electrical path adjustment of piezoelectric transducer is circuit 1
This is done by 1.

2a, 2b and 2c are cross-sectional views of various structures for point application of droplets in a device with a flat transducer operating on the piezoelectric principle. In this case, the planar piezoelectric transducer 1 is electrically regulated by a circuit 11 . The planar piezoelectric transducer is located within the liquid chamber 12, which is connected to the supply chamber by a liquid passageway 13. One or more nozzle conduits 18 emanate from the liquid chamber 12;
Its capillary section 17 terminates in the outlet nozzle plate 6.
5 indicates a droplet of ejected liquid.

FIG. 3 is a schematic cross-sectional view of an alternative droplet point application system with the piezoelectric part omitted for clarity. Liquid is forced into the nozzle 24 from the liquid supply section 21 by the pump 22 through the filter 23 . The liquid jet 27 ejected by the nozzle 24 is divided into droplets 28, charged by a droplet charging ring 25 and deflected in an electric field by a deflection plate 26. The deflected liquid droplet 29 is captured by the suction electrode 100, collected, and returned to the container 21 via the passageway 110.

FIG. 4 is a cross-sectional view of a similar droplet point application system in which the lubricant is carried by a transport liquid. A liquid supply container 31 contains a transport liquid, which is forced through a filter 33 into a nozzle 34 by a pump 32 . This tube 30 contains a lubricant liquid or suspension carried along a nozzle 34a, which lubricant liquid or suspension is carried by a jet 37 of transport liquid discharged from the nozzle 30. The mixed jet 37 is divided into droplets 38 and the droplet charged ring 35
is electrically charged. This droplet 38 is
6, it is electrostatically deflected in the desired direction and this deflected droplet 39 is applied point-wise to a specific point on the compression device. The undeflected droplets are removed by the suction electrode 100.

The piezoelectric transducer is omitted in FIGS. 3 and 4; in these cases the piezoelectric transducer is e.g. It can be installed within the supply container 21 or 31 or in the supply container 21 or 31.

The droplet spot application system according to the invention simultaneously provides the following advantages:

The system does not require any mechanism other than the use of a piezoelectric oscillator, so it is virtually wear-free.
Even the supply of liquid used for spot application of small drops
It is carried out independently by the capillary force of the conduit.

Droplet formation ranges from several hundred per second through the conduit.
It is stable and extremely accurate even when delivering as many as 15,000 droplets. The droplet spot application can be sized to accommodate even the smallest tablet or capsule filling machines. The spot application of droplets can be arranged to direct the droplets in any desired direction.

The droplet spot application system of the present invention emits only droplets of equal weight, whereas single-substance nozzles or dual-substance nozzles have a droplet distribution ranging from mist to coarse droplets.

It can be particularly emphasized that the droplet spot application system described above allows rapid and precise operation. This system is compatible with all hitherto known high speed tableting processes. Release of lubricant liquid or suspension is 1
Done within milliseconds. The amount released is constant. The lubricant is applied precisely to the parts of the device where the use of lubricant is required. Previously known systems, such as spraying of lubricant liquid from a nozzle, produce droplets distributed from mist to coarse droplets, where the coarse droplets disturb the uniform distribution of the lubricant and the mist is compacted. This results in jamming of the board or tablet press. Previously known systems do not permit adjustments such as applying lubricant more intensively to particularly stressed areas of the compression device than to less stressed areas.

The following examples illustrate the method of the invention.

Example 1 After thoroughly mixing 40 kg of indomesacin, 159 kg of lactose, 200 kg of corn starch, 14 kg of colloidal silica and 6 kg of polyvinylpyrrolidone,
Granulate by conventional method. An aqueous solution of 10 kg of soluble starch is used for granulation.

The granules were compressed in a double rotary tablet press at a speed of 220,000 tablets per hour, and the hole walls and the working surface of the punches were filled with a half-saturated ethanolic solution of glycerol monostearate, actuated by piezoelectricity. The droplets are deposited in a dot by a droplet dot application system. twenty four
The tube operates at a frequency of 10 droplets per millisecond, and the compression section deposits droplets in a dotted manner for about 5 milliseconds as it passes. Droplet weight is approximately 0.0006mg
It is. The maximum peel force at this tableting speed is 35% higher than that of a tablet containing 1.0% magnesium stearate in the granules.

Example 2 A powder mixture for hard gelatin capsules is prepared by mixing the active substance, lactose, corn starch and colloidal silicic acid. A small droplet device is installed approximately 1 mm directly below the filling tube of the capsule filling machine. A planar piezoelectric oscillator is placed on top of the liquid conduit of the device, and the end of the conduit is closed by a nozzle plate with 42 openings of 0.06 mm diameter. During 1 millisecond, 0.1 mg of a 5% alcohol suspension of magnesium stearate is released inside the filling tube. In the release of active substances from this capsule
When tested in vitro, the release of the active substance was faster (releasing time of 90% of the active ingredient was 35 minutes) compared to capsules manufactured by the conventional method (2% magnesium stearate added to the granules). 10 minutes).

[Brief explanation of drawings]

Figures 1 to 4 are diagrams schematically showing examples of apparatuses that can be used to carry out the method of the present invention, and Figure 1 is a schematic cross-sectional view of a point application system for small droplets. In the figure, 1 is a piezoelectric transducer, 2
is a liquid distribution chamber, 3 is a liquid supply section, 4 is a overplate, 5
6 is an ejected liquid droplet, 6 is an outlet nozzle plate, 7 is a capillary section, 8 is a nozzle conduit, 9 is a liquid passageway, 10 is a drainage groove, and 11 is a regulating circuit. Figure 2a, 2nd
Figures b and 2c are cross-sectional views illustrating drip sections with various structures, in which 12 is a liquid distribution chamber, 13 is a liquid conduit, 17 is a thin tube part, and 18 is a nozzle conduit (the others are the same as those in Figure 1). (same as in case). FIG. 3 is a schematic cross-sectional view of another droplet point application system, 21 is a supply vessel, 22 is a pump, 23 is a filter, 24 is a nozzle, 25 is a droplet charging ring, and 26 is a deflector. 27 is the ejected liquid jet, 28 is the water droplet, 29 is the deflected liquid droplet, 100 is the suction electrode, and 110 is the liquid passage. FIG. 4 is a cross-sectional schematic diagram of a spot application of droplets similar to FIG. 3 in which the lubricant is carried by a transport liquid, 30 is a lubricant tube, 31 is a liquid supply container, 32 33 is a pump, 34 is a nozzle, 35 is a droplet charging ring, 36 is a deflection plate, 37
is a liquid jet, 38 is a liquid droplet, 39 is a deflected droplet, and 100 is a suction electrode.

Claims (1)

[Claims] 1. A method of intermittently coating a molding device for producing molded articles for use as a medicine, food, or catalyst with a liquid or suspension lubricant before each compression operation. using a piezoelectric transducer 1 to apply the lubricant in a specific amount and in the form of discrete droplets 5, 28, 38 of a defined constant volume and at a defined rate; A coating method characterized in that it is applied and deposited directionally in dots in the pressurized area of a compression device. 2 nozzles 6, which are geometrically arranged with droplets formed by piezoelectric transducers;
7. The method according to claim 1, wherein the method uses the method of claim 1. 3. The method of claim 1, wherein the droplet formed by the piezoelectric transducer is placed in place by electrostatic or electromagnetic deflection of its travel path. 4. The coating method according to claim 1, wherein the liquid or suspended lubricant is applied pointwise as droplets using a piezoelectric transducer located around the nozzle conduit. 5. Any one of claims 1 to 4, wherein a certain number of lubricant droplets suitable for a particular area of the forming device are applied in a dotted manner independently of each other. The coating method described in item 1. 6 Operation of point-wise application of droplets by means of piezoelectric transducer 1 The ejection of droplets from a liquid under pressure is carried out using a transducer having a partial or total outlet opening. 5. A coating method as claimed in claim 1, which is carried out by adjusting the opening and closing of the outlet opening. 7 A method of intermittently coating a molding device for producing molded articles for use as a medicine, food or catalyst with a liquid or suspension lubricant before each compression operation, the method comprising piezoelectric Using the transducer 1, the lubricant is applied in a specific amount and by means of geometrically arranged nozzles 6, 7 or by electrostatic or electromagnetic deflection 29, 39 of the path of the droplets. Apparatus for carrying out a coating method for point-wise application and deposition in the pressurized area of a compression device in the form of discrete droplets 5, 28, 38 of a defined constant volume and at a defined speed. one or more conduits 8 each partially or wholly having a circular or slit-shaped outlet opening 6 at one side or at one end 6 consisting of a piezoelectric transducer 1, the conduit terminating in a narrow outlet opening 7;
The device is characterized in that the conduit is connected to a liquid supply container 3. 8. The piezoelectric transducer itself is optionally constructed integrally with a liquid conduit 8, which conduit 8 has one or more circular or slit-shaped outlet openings. The device described. 9 the conduit 8 is bent at the front or rear of the piezoelectric transducer 1 and/or the conduit 8 branches into two or more conduits downstream of the piezoelectric transducer;
and if necessary the piezoelectric transducer is assisted by a second or several piezoelectric transducers.
Equipment described in Section. 10. The device of claim 9, wherein the geometry of the conduits is adapted to the configuration of the die (male forming device) and the bore (female forming device).