EP0299065A1

EP0299065A1 - Apparatus for constant feeding and mixing of granular or powder materials

Info

Publication number: EP0299065A1
Application number: EP86903566A
Authority: EP
Inventors: Kiyoshi Morimoto; Masuo Moriyama
Original assignee: Kyowa Hakko Kogyo Co Ltd
Current assignee: KH Neochem Co Ltd
Priority date: 1986-05-23
Filing date: 1986-05-23
Publication date: 1989-01-18
Also published as: WO1987007182A1; EP0299065A4; KR880701131A

Abstract

Apparatus for automatic weighing, feeding and mixing of raw granular or powder materials, consisting of storage tanks for at least two different kinds of materials, means for weighing desired quantities of the raw materials from the storage tanks, means for discharging and transferring the weighed granular or powder materials into a mixing tank, a means for mixing the weighed granular or powder materials, and a means for holding a constant quantity of the resultant mixture, all of these means being integrally arranged.

Description

Technical Field

This invention relates to an apparatus for feeding predeterminate quantity of powdery particles and mixing thereof, and more particularly to an apparatus for automatically feeding at least two different kinds of raw material powdery particles in predetermined amounts and mixing the powdery particles. By combination of such an apparatus with a tableting machine, etc., tablets can be automatically and efficiently produced from raw materials.

Background Art

Applicable range of compression shaping or processing of various powdery particles into tablets, capsules, etc. have recently been extended to the production of compression moldings of food, electronic parts, mechanical parts, chemicals, etc., to say nothing of the production of tablets of medicaments. Such a remarkable spread is based on the fact that quality and/or function can be improved by shaping (solidifying) the powdery particles.
Heretofore, apparatuses for feeding a single kind of raw material into a hopper provided in a tableting machine and automatically tableting the powdery material have been commercially available. In the case of at least two different kinds of raw materials, they are mixed together in advance, and the mixture is fed into a hopper and tableted. However, no apparatus for automatically mixing at least two different kinds of raw materials at predeterminate rates and feeding them into a tableting machine has not been developed so far.
There are many problems to be solved in the steps of mixing different kinds of raw materials and automatically feeding them into a tableting machine.
For example, in the case of compression shaping powdery particles by a compression shaping machine, a process for mixing different kinds of raw material powdery particles, for example, main raw material powdery particles and a lubricant (usually inorganic salt of stearic acid, talc and the like are used) in the tableting, is necessary as a preliminary step.
Problems, etc. in the case of producing tablets of medicaments are set forth below, and similar problems arise in the compression shaping, etc. in other fields.
The general process for producing tablets is given below.

(1) Wet tableting process

(2) Direct tableting process

The object of mixing in these processes falls into two groups; to unify the content of main components and to uniformly mix, with the other components, the lubricant as added in order to prevent troubles in the tablet production. The former process has relatively few troubles, because the uniformity can be attained by advance mixing before the mixing prior to the tableting, that is, by mixing of the main components with an excipient after the raw material weighing, or the uniformity can be attained in the successive granulation step.
In the latter process, on the other hand, addition of an appropriate amount of a lubricant to granulated main raw material powdery particles (main medicament, excipient, binder, etc.) as prepared by a granulator, or to ungranulated powdery particles and mixing them, have such objects as to (1) lighten pressure transmission at the compression shaping, (2) enhance the flowability of powdery particles, thereby improving the die packing density, making tablet characteristics such as control of weight variation, etc. always uniform, and stabilizing the quality, and (3) improve the releasability of the tablets from the punch, thereby reducing the die wall friction coefficient at the discharge, etc., and thus the mixing operation before the tableting plays a very important role. Generally, the types of mixers used for this purpose are vessel-rotating, batch types (which are destined to a small volume mixing for varied items and whose lot batch size depends upon a mixer volume = loading ratio), such as V-shaped type, double conical type, cubic type, horizontal cylindrical type, and inclined cylindrical type.
The mixing step using these batch-type mixers and the successive step of feeding the powdery particles into a tableting machine have the following problems.
(1) A large space is required for installing a mixer and mixing operation, (2) feeding or discharging operation, etc. of the powdery particles into or from the mixer mostly rely on workers, and undesirable environmental troubles such as dust generation, etc. are aroused, (3) separation and segregation of a lubricant, when occurred in batch mixing of main raw materials (powdery particles granulated by a granulator, etc.) with the lubricant and pneumatically conveying the resulting mixture to a hopper in a tableting machine, lead to fluctuation of tablet weight during the tableting, uneven content of the medicament, capping, lamination, sticking, reduced hardness, etc., which debase the quality, (4) a way to convey the powdery particles to a tableting machine is restricted, resulting in a bar to continuation and automation of successive steps, and (5) such risks are incurred as contamination with foreign matters, etc., because the mixing operation mostly relies on manual labor which causes failure of tight sealing.
The foregoing problems can be substantially solved, if an apparatus for automatically feeding and mixing at least two kinds of raw materials is developed.

Disclosure of Invention

The present invention relates to an apparatuse for automatically feeding predeterminate quantity of powdery particles and mixing thereof, systematically provided with storage vessels for at least two different kinds of raw material powdery particles, a means for weighing desired amounts of the raw material powdery particles from the respective storage vessels, a means for discharging and transporting the weighed powdery particles to a mixing means, a means for mixing the respective weighed powdery particles, and a vessel for holding a predeterminate amount of the mixture (the apparatus is hereinafter referred to as the apparatus of the present invention).
By combining and integrating the apparatus of the present invention with a compression shaping machine such as a tableting machine, etc., and processing and treating apparatuses such as a capsule-filling machine, a granule-dispensing machine, etc., the entire system can be made more compact and convenient for processing.
One example of using two kinds of raw materials in an apparatus based on a combination of the apparatus of the present invention with a tableting machine is shown in Fig. 1.
The present invention is described in detail below, referring to the drawing. It is needless to say that other units having equivalent functions can be used in the present invention in place of the respective units.
One kind of raw material powdery particles is placed in a raw material storage vessel (1) 3, and fed to a weighing vessel (1) 7 provided with a balance 8 through an electromagnetic feeder through 5 by means of an electromagnetic feeder 6. Likewise, another kind of raw material powdery particles in a raw material storage vessel (2) 16 is fed to a weighing vessel (2) 19 provided with a balance 20 through an electromagnetic feeder through 17 by means of an electromagnetic feeder 18.
. When predeterminate weights of the raw materials are fed to the respective weighing vessels, operation of the electromagnetic feeders is discontinued through the balances.
The predeterminate weights of the raw materials fed to the weighing vessels are confirmed by checking if they are within a range of predetermined error in measurement by a weight-setting comparator 26. After the confirmation of the weighed amounts, the respective raw materials are sent to a mixer 11 by a raw material discharge valve 10 or 22.
The presence or absence of the powdery particles remaining in the respective weighing vessels is confirmed by the weight-setting comparator 26 through the respective balances, or by a raw material discharge-checking sensor 9 or 21 provided at the respective weighing vessels.
Then, a mixer-stirring motor 13 at the mixer 11 is started to mix the raw materials with stirring blades 14. After the mixing for a predeterminate time, the mixture is supplied to the vessel 23 for holding the powdery particles mixture with stirring through the powdery particle discharge valve 15 until a predeterminate amount of the powdery particle mixture is defected by a powdery particle-detecting sensor 24 provided at the vessel 23, and then the valve 15 is closed.
The mixture in the vessel 23 for holding the powdery particles is supplied to a tableting machine through an appropriate supply means, and tableted.
As the valves, valves, shutters, etc. utilizing electricity or compressed air can be used. In place of the electromagnetic feeder, a screw feeder, a table feeder, etc. can be used. Furthermore, an electromagnetic feeder, a screw feeder, a table feeder, etc. can be used in place of the raw material-discharge valve.
In transferring the raw material from one vessel to another, a valve is convenient as a means for transferring the raw material, when the vessels are to be vertically located, but an electromagnetic valve, etc. are preferable when a control over the feeding of trace amounts of powdery particles is required.
These steps can be carried out from the start in order, but the steps having no influence on each other may be carried out independently.
In the successive operation, it is possible to set a time schedule by a timer so as to establish control over the starting of the successive step after the completion of the preceding step has been confirmed, but a software may be set up in a computer so that the start and completion of the respective steps can be confirmed, and such a design can be made very easily by those skilled in the art. When the weighed amounts in the respective steps are automatically recorded, the successive control can be made more easily. When an abnormal state occurs in the steps, a circuit must be set up to emit an alarm and discontinue operation of the apparatus entirely or partially.
An example of a system for automatic control of the apparatus of the present invention connected with a tableting machine is described below, referring to Fig. 1.

(a) Different kinds of raw materials are placed into two raw material storage vessels. Raw material (1) is led to the weighing vessel 7 from the raw material storage vessel 3 by the electromagnetic feeder 6. The electromagnetic feeder 6 is started at the time when the mixture in the mixer is decreased to less than a predeterminate amount, which is detected by a powdery particle volume detector 12. When the amount detected by the balance 8 is ascertained to be the predeterminate amount by the weight-setting comparator, the operation of the electromagnetic feeder 6 is discontinued.
(b) After the discontinuation is checked, a similar step to (a) is repeated to supply the raw material (2) from the raw material storage vessel (2) 16 to the weighing vessel 19.
(c) After the completion of steps (a) and (b) is checked, the raw material discharge valve 10 or 22 is opened to supply the raw materials to the mixer 11. At that time when it is ascertained that no raw material in the respective weighing vessels remains, the valve is closed.
(d) After the completion of step (c) is checked, the mixer stirring motor 13 is started to stir the raw materials for a predeterminate time.
(e) After the stop of the motor is checked, the powdery particle discharge valve 15 is opened to supply the mixture to the vessel 23 for holding the powdery particles, and when the predeterminate amount is detected by the powdery particle-detecting sensor 24, the valve is closed. This valve is controlled to be closed while in any one of the steps (a)-(c), operation is carried out.

The foregoing affords an example of control, and it can be modified variously. Such modifications can be easily made by those skilled in the art.
When 3 or more different kinds of raw materials are used, necessary sets of units and means for automatic feeding of the raw materials from the raw material storage vessels to the mixer must be incorporated in the apparatus according to the number of the added raw materials.
Various devices can be added to the apparatus of the present invention in order to simplify attachment or detachment of the apparatus to a processing and treating apparatus in the successive step, and to enable the entire apparatus to be washed with water, etc. For example, to prevent retention of powdery particles in a vessel, the contact part with the powdery particles is coated with a special complex resin, and all the corners are made to have round surfaces to eliminate dead spaces. To simplify attachment and detachment of the essential parts, a one-touch coupling is used. All the valves must be of sanitory type and readily washable. The detectors, weighing sections, and bearing sections must be in a water-proof structure.
Test examples of the present invention are outlined below. Raw materials and their composition for carrying out the tests are shown in Table 1, characteristics of granulated powdery particles prepared by a fluidized bed granulator in Table 2, and operating conditions of a tableting machine in Table 3.
The main raw material powdery particles were prepared by spray-granulating an aqueous solution of HPC-L on a mixture of lactose and potato starch with heating in a fluidized bed ganulator.

Test Example 1

The apparatus of the-present invention was continuously operated for 5 hours, as connected with the tableting machine to investigate the produced tablets on the tablet characteristics such as fluctuation of tablet weight with the elapse of time, hardness, capping, sticking, etc., and its behavior was observed. As a control, a mixture of the main raw material powdery particles and the lubricant in a ratio of 99:1, shown in Table 1, mixed with a V type mixer prevalently used, was used.
In Table 4, the tablet characteristics in the case of using the V type mixer and those in the case of using the apparatus of the present invention are shown.
At every 30 minutes, 50 tablets were sampled, and the behavior over 5 hours was observed. Better results than those from the V type mixer were obtained in the fluctuation of weight and the hardness. Neither capping nor sticking was observed in both tests.

Test Example 2

Magnesium in the magnesium stearate contained in the tablets obtained in the foregoing Test Example 1 was quantitatively determined by atomic absorption analysis to compare the content in tablets produced by the use of the V-type mixer with that in tablets produced by the use of the apparatus of the present invention. As shown in Table 5, the fluctuation in mixing with the elapse of time is smaller and the apparatus of the present invention is advantageous in uniformity of the content in tablets.

Test Example 3

Compression shaping pressure of tablets and release pressure thereof from a die, based on the mixing ratio of the lubricant were measured together with the tablet characteristics with the elapse of time of the foregoing Test Example 1. The results are shown in Table 6. In comparison with the case of V-type mixer, the apparatus of the present invention had a tendency to improve the pressure transmission, reduce the pressure at the compression shaping and also reduce the release pressure of tablets from the die wall.
Time required for dismantling, washing and drying of the apparatus of the present invention was about 40 minutes, and the apparatus was found to be competent to be practically used.

Brief Description of Drawing

Fig. 1 gives one embodiment illustrating a combination of an apparatus for feeding predeterminate quantity of powdery particles and mixing thereof according to the present invention with a tableting machine, where the respective members are given as follows:

1: entire apparatus, 2: raw material conveying pipe, 3: raw material storage vessel (1), 4: raw material-detecting sensor, 5: electromagnetic feeder through (1), 6: electromagnetic feeder (1), 7: weighing vessel (1), 8: balance (1), 9: raw material discharge-detecting sensor (1), 10: raw material discharge valve (1), 11: mixer, 12: powdery particle volume detector, 13: mixer stirring motor, 14: stirring blades, 15: powdery particle discharge valve 16: raw material storage vessel (2), 17: electromagnetic feeder through (2), 18: electromagnetic feeder (2), 19: weighing vessel (2), 20: balance (2), 21: raw material discharge-detecting sensor (2), 22: raw material discharge valve (2), 23: vessel for holding mixture, 24: powdery particle-detecting sensor, 25: driving motor, 26: weight-setting comparator, 27: recorder, 28: control box.

Claims

1. An apparatus for automatically feeding predeterminate quantity of powdery particles and mixing thereof, systematically provided with storage vessels for at least two different kinds of raw material powdery particles, a means for weighing desired amounts of the raw material powdery particles from the respective storage vessels, a means for discharging and transporting the weighed powdery particles to a mixing means, a means for mixing the respective weighed powdery particles, and a means for holding a predeterminate amount of the mixture.

2. An apparatus for automatically feeding predeterminate quantity of powdery particles and mixing thereof according to Claim 1, wherein said apparatus is combined with a compression shaping apparatus or a processing-treating apparatus.

3. An apparatus for automatically feeding predeterminate quantity of powdery particles and mixing thereof according to Claim 2, wherein the compression shaping apparatus is a tableting machine.

4. An apparatus for automatically feeding predeterminate quantity of powdery particles and mixing thereof according to Claim 2, wherein the processing-treating apparatus is a capsule-filling machine or a granule-dispensing machine.

5. An apparatus for automatically feeding predeterminate quantity of powdery particles and mixing thereof according to Claim 1, wherein the means for weighing desired amounts of the raw material powdery particles from the respective storage vessels are apparatuses with a mechanism of feeding the powdery particles from the respective storage vessels to a weighing vessel through an electromagnetic feeder, and discontinuing operation of the electromagnetic feeder by a balance provided in the weighing vessel when the raw materials in the vessel reaches a predeterminate amount.

6. An apparatus for automatically feeding predeterminate quantity of powdery particles and mixing thereof according to Claim 5, wherein a mechanism of ascertaining that the amount of the powdery particles fed to the weighing vessel is the predeterminate amount is provided.

7. An apparatus for automatically feeding predeterminate quantity of powdery particles and mixing thereof according to Claim 5, wherein a mechanism of ascertaining that the weighing vessel is substantially free from the remaining raw materials after the raw materials are discharged from the weighing vessel to the mixer is provided.

8. An apparatus for automatically feeding predeterminate quantity of powdery particles and mixing thereof according to Claim 1, wherein a mechanism of automatically carrying out all the steps as far as the raw materials in the storing vessels for raw material powdery particles are supplied to the means for holding a predeterminate amount of the mixture is provided.

9. An apparatus for automatically feeding predeterminate quantity of powdery particles and mixing thereof according to Claim 8, wherein a mechanism of stopping operation of the apparatus partially or entirely when an abnormal state brings about in the steps is provided.