WO1996027125A1 - Method and device for the investigation of the humidity-related behaviour of powders - Google Patents
Method and device for the investigation of the humidity-related behaviour of powders Download PDFInfo
- Publication number
- WO1996027125A1 WO1996027125A1 PCT/FI1996/000096 FI9600096W WO9627125A1 WO 1996027125 A1 WO1996027125 A1 WO 1996027125A1 FI 9600096 W FI9600096 W FI 9600096W WO 9627125 A1 WO9627125 A1 WO 9627125A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- sample
- samples
- atmosphere
- processor
- disc
- Prior art date
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N5/00—Analysing materials by weighing, e.g. weighing small particles separated from a gas or liquid
- G01N5/02—Analysing materials by weighing, e.g. weighing small particles separated from a gas or liquid by absorbing or adsorbing components of a material and determining change of weight of the adsorbent, e.g. determining moisture content
- G01N5/025—Analysing materials by weighing, e.g. weighing small particles separated from a gas or liquid by absorbing or adsorbing components of a material and determining change of weight of the adsorbent, e.g. determining moisture content for determining moisture content
Definitions
- the invention relates to a method and apparatus for studying hygroscopic behaviour of a powder material.
- hygroscopic behaviour denotes moisture adsorption or desorption of the material in air with known relative humidity. The term also covers the rate of said moisture adsorption or desorption as well as the equilibrium moisture content of the material.
- a material may adsorb moisture i.e. it is hygroscopic, desorb moisture i.e. it is efflorescing or neither of the mentioned phenomena occurs .
- the material is in an equilibrium state with the surrounding atmosphere and the moisture content of the material is then called the equilibrium moisture content.
- the equilibrium moisture content of a material depends, besides on the physical and chemical properties of the material itself, on the relative humidity and temperature of the surrounding atmosphere.
- Adsorption isotherm is a curve that describes the equilibrium moisture content of the material as a function of the relative humidity of the atmosphere at constant temperature (Fig. 1).
- Adsorption isotherm describes a situation wherein the starting moisture content of the material has been lower than the equilibrium moisture content at that atmosphere to which the material has been exposed. If, on the contrary, the material has been conditioned to equilibrium moisture content in an atmosphere with very high relative humidity and the material is exposed to an atmosphere with a lower relative humidity, the equilibrium moisture content of the material will settle on a value above the adsorption isotherm i.e. on the desorption isotherm (Fig.
- Fig. 2 shows weight change of a material as a function of time when dry samples have been exposed to atmospheres with different relative humidities. If two or more powders must be mixed and processed into a final product, it is essential to know how these materials affect the hygroscopic behaviour of one another. For example in pharmaceutical industry, it has been observed that uncontrolled hygroscopic behaviour of powder raw materials cause all kinds of problems in the manufacture of solid drugs such as tablets. Poor tabletting is often corrected by changing the moisture content of the tabletting mass.
- the apparatus comprises a microbalance coupled to a computer, a sample container suspended from the balance, a humidity chamber and a lift whereby the humidity chamber can be lowered or lifted so that it surrounds the sample under study.
- the humidity chamber is a vessel which opens upwards.
- the relative humidity in the humidity chamber can be controlled with various saturated salt solutions by putting such a saturated salt solution in the vessel that produces the desired humidity.
- Table 1 presents some suitable salt solutions and the relative humidities they produce.
- Silica gel provides 0 % and water 100 % relative humidity.
- a water bath is around the humidity chamber which can also be lowered and lifted.
- the water bath allows control of the temperature in the humidity chamber.
- the apparatus is used so that a small amount of sample is placed in the container suspended from the microbalance and initial weighing is performed. Then the humidity chamber is lifted around the sample container.
- the humidity chamber is lifted around the sample container.
- By monitoring and taking the balance readings of the sample to the computer one obtains the change in the moisture content of the sample as a function of time.
- the equilibrium moisture content of the sample in the relative humidity in question has been reached.
- the equilibrium moisture content of the material in another relative humidity is obtained.
- the mentioned values of the equilibrium moisture content constitute points on the adsorption/desorption isotherm curve of the material .
- Fig. 1 shows the adsorption and desorption isotherms of a material
- Fig. 2 shows the weight change of a material as a function of time when dry samples have been exposed to atmospheres of different relative humidities.
- Fig. 3 shows an apparatus according to the invention
- Fig. 4 shows a sample carousel of the apparatus of Fig.
- Fig. 5 shows another embodiment of the sample carousel of the apparatus of Fig. 3
- Fig. 6 shows a sample container provided with a handle.
- Fig. 3 shows one solution for the apparatus to realize the method of the invention.
- the apparatus comprises a balance 1 connected to a programmed processor 15, from which balance hangs a suspension string 3 with a hook to carry a sample container 20.
- Fig. 4 shows in greater detail how the different sample containers 20a, 20b, 20c ... have been placed on the carousel 4.
- Fig. 6 shows that the sample container 20 is provided with a handle 25 for lifting the container.
- the sample container is preferably provided with a wide bottom so that the sample can be spread onto it as a thin layer so that the sample becomes efficiently ventilated.
- the humidity chamber 2 can be fitted around the carousel 4 by hoisting with a lift 9.
- a desired relative humidity can be accomplished in the humidity chamber 2 by placing a suitable salt solution 7 onto the bottom of the chamber 2.
- the rotation of a vertical axle 16 coupled to a motor 5 is transmitted to the carousel 4 which may be rotated in either direction as indicated by the arrows.
- Temperature in the humidity chamber 2 can be controlled by a water bath 8 placed around it.
- Fig. 3 shows the humidity chamber 2 together with the surrounding water bath 8 in the uplifted position.
- Humidity and temperature probes are marked with the reference number 6.
- Reference number 13 denotes the data transmission cables between the processor and the balance.
- Reference number 14 denotes the data transmission cables between the processor and the motor 5 driving the carousel 4 and the motor 10 driving the lift 9.
- Reference number 11 denotes the frame of the apparatus and number 12 the casing protecting the balance.
- the vertical axle 16 connected to the carousel 4 is arranged movable also in its longitudinal direction as indicated by the arrow.
- the apparatus is operated in the following way.
- the lift 9 lowers the humidity chamber 2 with its water bath 8.
- Samples Nl , N2, N3, .. are placed into tared sample containers 20a, 20b, 20c...
- the vertical axle is lifted with the motor 5 so that the plate 4 reaches such a height that the hook in the suspension string 3 goes through the handle 25a of the sample container 20a when the plate 4 is rotated by the motor 5 in clockwise direction.
- the rotating motion of the plate 4 is halted and the plate 4 is lowered down so that the sample container is left hanging from the suspension string 3 and weighing takes place.
- the weight reading is transferred to the processor 15.
- the plate 4 After the weighing, the plate 4 is lifted up so as to leave the sample container resting on the plate, the plate is slightly rotated counterclockwise to release the hook of the suspension string 3, the plate is lowered and it is rotated clockwise so that the sample container 20a passes the hook. Then the plate is lifted to a suitable height for attaching the next sample container 20b with the hook of the suspension string 3 and all the above operations are repeated at each sample container. It is important for successful weighing of the different samples that the containers be situated at equal distance from the centre of the plate and therefore the disc 4 may have marked places for the sample containers. Control is preferably realized so that the rotating motion of the disc is halted when the disc is lifted or lowered. Initial weighing of the different samples should be done in the shortest possible time and therefore the plate is rapidly rotated to the subsequent sample to be weighed.
- the humidity chamber 2 is lifted so that it surrounds the carousel with its samples and the sample containers are weighed each in turn in the manner described above.
- the computer program notes the weight reading and the point of time of weighing for each sample. The test may be carried out so that immediately after the first weighing round a second weighing round is carried out and so on. In this case the carousel is continuously in motion. Alternatively, a specific pause may follow different weighing rounds. This is a good practice if the weight readings of the samples do not vary very rapidly as a function of time in the atmosphere of the humidity chamber. From the weight readings of samples Nl, N2, N3,... taken from the same material to be studied, the moisture adsorption or desorption curve which fits best to all the weight readings obtained can be calculated with the processor for the material in question.
- the equilibrium moisture content of the material in question can be calculated at the temperature and relative humidity of the ambient atmosphere.
- the carousel 4 may optionally be a circular disc rotating in a vertical plane as shown in Fig. 5.
- An axle (not shown in the figure) passing through the centre of the disc is at right angles to the vertical axle 16 and transmits its rotating movement to the disc 4.
- the seats are preferably mounted on bearings to the disc so as to maintain a constant position despite the rotating motion of the disc. This can be simply accomplished e.g. by suspending weights from the seats preventing them from turning upside down.
- the method according to the invention may of course be carried out by solutions other than the one described above.
- the suspension string connected to the balance is moving and the plate with its sample containers remains stationary.
Abstract
Description
Claims
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP96903016A EP0820582A1 (en) | 1995-03-01 | 1996-02-19 | Method and device for the investigation of the humidity-related behaviour of powders |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FI950926A FI108674B (en) | 1995-03-01 | 1995-03-01 | Method and apparatus for studying the moisture behavior of a powdered substance |
FI950926 | 1995-03-01 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1996027125A1 true WO1996027125A1 (en) | 1996-09-06 |
Family
ID=8542946
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/FI1996/000096 WO1996027125A1 (en) | 1995-03-01 | 1996-02-19 | Method and device for the investigation of the humidity-related behaviour of powders |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP0820582A1 (en) |
CA (1) | CA2214345A1 (en) |
FI (1) | FI108674B (en) |
WO (1) | WO1996027125A1 (en) |
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
ES2123413A1 (en) * | 1996-02-09 | 1999-01-01 | Univ Cadiz | Procedure for studying sorption processes in porous nature solid material and device for its implementation |
ES2129374A1 (en) * | 1997-11-10 | 1999-06-01 | Univ Cadiz | Automated process for studying solid/water interaction processes, and an apparatus for implementing it |
WO2006070032A1 (en) * | 2004-12-22 | 2006-07-06 | Univesidad De Cádiz | Automated system and method for examining the transport properties of fluids in porous materials |
US7207211B2 (en) * | 2002-05-24 | 2007-04-24 | Symyx Technologies, Inc. | High throughput microbalance and methods of using same |
CN102914482A (en) * | 2012-08-30 | 2013-02-06 | 山东淄博新达制药有限公司 | Method for controlling quality during cefaclor granule production process |
CN105547902A (en) * | 2015-12-14 | 2016-05-04 | 贵州中烟工业有限责任公司 | Method for determination of moisture-proof curve of tobacco capsules |
CN113567292A (en) * | 2021-09-01 | 2021-10-29 | 上海烟草集团有限责任公司 | Method for evaluating moisture barrier performance of three-dimensional cigarette case package |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2575169A (en) * | 1948-09-17 | 1951-11-13 | Stromberg Carlson Co | Method of determining the rate of moisture absorption |
US4227399A (en) * | 1977-12-27 | 1980-10-14 | Groeninger Kurd | Apparatus for contacting samples with water vapors |
DE3922380A1 (en) * | 1988-09-27 | 1990-03-29 | Textima Veb K | Gravimetric measurement of absorption equilibrium - has moisture content in vapour atmosphere to maintain temp. difference between absorbent and vapour source material |
GB2234597A (en) * | 1989-08-03 | 1991-02-06 | Sartorius Gmbh | Drying and measuring apparatus |
-
1995
- 1995-03-01 FI FI950926A patent/FI108674B/en not_active IP Right Cessation
-
1996
- 1996-02-19 CA CA 2214345 patent/CA2214345A1/en not_active Abandoned
- 1996-02-19 WO PCT/FI1996/000096 patent/WO1996027125A1/en not_active Application Discontinuation
- 1996-02-19 EP EP96903016A patent/EP0820582A1/en not_active Withdrawn
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2575169A (en) * | 1948-09-17 | 1951-11-13 | Stromberg Carlson Co | Method of determining the rate of moisture absorption |
US4227399A (en) * | 1977-12-27 | 1980-10-14 | Groeninger Kurd | Apparatus for contacting samples with water vapors |
DE3922380A1 (en) * | 1988-09-27 | 1990-03-29 | Textima Veb K | Gravimetric measurement of absorption equilibrium - has moisture content in vapour atmosphere to maintain temp. difference between absorbent and vapour source material |
GB2234597A (en) * | 1989-08-03 | 1991-02-06 | Sartorius Gmbh | Drying and measuring apparatus |
Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
ES2123413A1 (en) * | 1996-02-09 | 1999-01-01 | Univ Cadiz | Procedure for studying sorption processes in porous nature solid material and device for its implementation |
ES2129374A1 (en) * | 1997-11-10 | 1999-06-01 | Univ Cadiz | Automated process for studying solid/water interaction processes, and an apparatus for implementing it |
US7207211B2 (en) * | 2002-05-24 | 2007-04-24 | Symyx Technologies, Inc. | High throughput microbalance and methods of using same |
WO2006070032A1 (en) * | 2004-12-22 | 2006-07-06 | Univesidad De Cádiz | Automated system and method for examining the transport properties of fluids in porous materials |
ES2259898A1 (en) * | 2004-12-22 | 2006-10-16 | Universidad De Cadiz | Automated system and method for examining the transport properties of fluids in porous materials |
CN102914482A (en) * | 2012-08-30 | 2013-02-06 | 山东淄博新达制药有限公司 | Method for controlling quality during cefaclor granule production process |
CN105547902A (en) * | 2015-12-14 | 2016-05-04 | 贵州中烟工业有限责任公司 | Method for determination of moisture-proof curve of tobacco capsules |
CN113567292A (en) * | 2021-09-01 | 2021-10-29 | 上海烟草集团有限责任公司 | Method for evaluating moisture barrier performance of three-dimensional cigarette case package |
Also Published As
Publication number | Publication date |
---|---|
CA2214345A1 (en) | 1996-09-06 |
FI950926A0 (en) | 1995-03-01 |
FI950926A (en) | 1996-09-02 |
FI108674B (en) | 2002-02-28 |
EP0820582A1 (en) | 1998-01-28 |
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