DD147414B1 - Method and device for determining the surface accountability - Google Patents

Method and device for determining the surface accountability Download PDF

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Publication number
DD147414B1
DD147414B1 DD21718579A DD21718579A DD147414B1 DD 147414 B1 DD147414 B1 DD 147414B1 DD 21718579 A DD21718579 A DD 21718579A DD 21718579 A DD21718579 A DD 21718579A DD 147414 B1 DD147414 B1 DD 147414B1
Authority
DD
German Democratic Republic
Prior art keywords
liquid
wetting
slope
angle
dynamic
Prior art date
Application number
DD21718579A
Other languages
German (de)
Other versions
DD147414A1 (en
Inventor
Roland Lipp
Ernst-Otto Reher
Ludwig Grader
Christine Hoffmann
Original Assignee
Wolfen Filmfab Veb
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Wolfen Filmfab Veb filed Critical Wolfen Filmfab Veb
Priority to DD21718579A priority Critical patent/DD147414B1/en
Publication of DD147414A1 publication Critical patent/DD147414A1/en
Publication of DD147414B1 publication Critical patent/DD147414B1/en

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Description

Field of application of the invention
The invention relates to a method for determining the wettability of a surface by a liquid. The determination of wetting properties of liquids on surfaces is needed in coatings and other processes in which liquids and surfaces come into contact.
Characteristic of the known technical solutions
The determination of the wetting properties of liquids on surfaces is often made by measuring the equilibrium edge angle that the liquid forms on the surface.
The size of the equilibrium edge angle is a measure of the wettability. In DE-OS 2053390 a method for determining the wettability of a surface is described, in which a plurality of liquid droplets applied to the surface are illuminated and the illumination angle is changed until reaching the critical angle of reflection to the observer.
With this method, the equilibrium edge angle at which the liquid is at rest can be determined with sufficient accuracy. However, it is not possible to make a statement about the wetting properties when the liquid is in motion. It is known to the person skilled in the art that the dynamic wetting behavior of liquids on surfaces clearly differs from that in the stationary state. For the determination of the dynamic wetting behavior, a method is recommended according to DD-WP 117528 in which a hanging meniscus of the liquid is generated on a rotating test cylinder. By this method statements about the dynamic wetting behavior of the liquid on the test cylinder are possible. However, the method has a number of significant disadvantages. The test cylinder is wetted several times during the measurement. Thus, the wetting behavior of a liquid on an unwetted surface is not detectable. Furthermore, the production of cylinders having the surfaces to be examined, very expensive and not feasible in all cases. This greatly limits the examination of a wide variety of surfaces. It has also been found that the determination of the wetting speed from the peripheral speed of the rotating cylinder is not sufficient to characterize the dynamic wetting behavior of the liquid.
Another way to determine the dynamic wetting behavior is described by GRIBANOWA and MOLTSCHANOWA in Kolloidnui Zumal 40 (1978) No. 1,30. It proposes to allow the liquid to rise in cylindrical glass capillaries and to detect the speed of wetting and the wetting angle by means of photomicrography.
This method is suitable for measuring the dynamic contact angle at low and medium wetting speeds.
However, it has the serious disadvantage that only the wetting of liquids on transparent capillaries can be investigated. This greatly limits the type of surfaces that can be used.
According to the method of ELLIOTT and RIDDIFORD (Journal of Oolide and Interface Sc 23 (1967, 389), a drop of liquid between two flat plates is increased to achieve a constant wetting speed, thereby determining the dynamic wetting behavior even on flat surfaces Despite the complicated and complicated liquid feed, the method can only achieve liquid speeds of less than 5.times.10.sup.- 4 m.s- 1 . This low speed in no way meets the technical requirements.
E. WOLFRAM (Kolloid Zeitschrift 182 [1962] 1 / 2,75) presents a method in which the inclination angle of a drainage slope is determined at which a drop located thereon starts to roll off. The obtained value of the angle is, however, only an expression of the static wetting and the phenomenon designated by the person skilled in the art as edge angle hysteresis. With the method described by WOLFRAM it is not possible to obtain information about wetting with moving liquid.
Object of the invention
The object of the invention is to allow a simple, fast and accurate determination of the dynamic wettability of a surface, to avoid wetting disturbances and to make wetting processes more effective.
-2- 147 Explanation of the nature of the invention
The technical solutions known for determining the wettability of surfaces have the disadvantage that conclusions about the dynamic wettability of surfaces can not be drawn from a quiescent droplet.
Other known technical solutions in which the dynamic wettability of surfaces can be determined, can not be applied to any flat surfaces, as to carry out the method certain geometries such. B. capillaries are required and / or caused by the geometries, low wetting speeds can be realized.
The invention is therefore based on the object to develop a method that allow determination of the dynamic wettability of any flat surfaces in the range of wetting speeds technically interesting.
According to the invention, this object is achieved in that the liquid is fed to a sloping to the horizontal slope, whose top surface to be examined, is abandoned, so that it runs under the action of gravity, that the shape of the surface of the effluent liquid in the wetting area and their Speed are detected.
The shape of the surface of the draining liquid in the wetting area can be photographically recorded. From the shape of the surface of the liquid running in the wetting region of the dynamic contact angle is determined as a criterion for the wettability of a surface at the corresponding wetting speed. The liquid can be applied continuously in the form of a constant flow of liquid to the drainage slope.
A preferred device for carrying out the method according to the invention consists of a drainage slope whose upper surface has the surface to be examined, and which can be inclined at an arbitrary angle in the range of 0 ° -90 ° relative to the horizontal, and a nozzle for discharging the liquid.
It is advantageous to attach to the drain slope a suitable scale so that the angle of inclination of the drainage slope relative to the horizontal can be read directly.
It is often necessary to examine the surface of a film. It is then appropriate to apply the film on the drainage slope. To get a good flatness, it can be sucked by vacuum. To maintain a certain temperature, it is advantageous to arrange a tempering chamber on the drainage slope or around the entire device.
At higher wetting velocities, the measurements of the velocity of the effluent liquid and the triggering of the optical device at the right time are difficult. It is therefore advantageous to attach two photoelectric sensors to the drainage slope so that they are interrupted one after the other by the draining liquid, measured via suitable electronics, the time difference or the speed of the liquid flowing out and also with a certain delay, the optical device is triggered.
embodiment
The invention will be explained in more detail below using an exemplary embodiment.
Fig. 1 shows an embodiment of the device according to the invention.
The device consists of a base plate 1 to which a stand 2 is attached.
A drainage slope 3 is connected to the stator 2 via a bearing 4. The drainage slope 3 is rotatably mounted and its inclination angle, which may be between 0 ° and 90 °, can be read on the scale 5. About the nozzle 6, the liquid to be examined can be abandoned from a reservoir 7 to the drainage slope 3. The nozzle 6 can be arbitrarily set in its inclination angle to the drainage slope 3. On the drainage slope 3 is a film 8 of the surface to be examined.
An optical device 9 is arranged such that with it the shape of the liquid surface in the wetting region can be detected. The device is preferably suitable for determining the surface wettability of films.
Fig. 2 shows schematically an image of the draining liquid 10 made with the aid of the optical device. This image is measured under a microscope and angle measuring table. The tangent 11 is applied to the surface of the effluent in the three-phase contact line, and the dynamic contact angle is determined as the angle between this tangent and the solid surface on the side of the effluent according to W. Rose and RW Heins and with Θ = 79.5 receive.

Claims (2)

  1. A method for determining the surface wettability of a liquid on a slope inclined to the horizontal, characterized in that one lets the liquid flow on the slope inclined to the horizontal slope, the shape of the surface of the liquid running in the wetting region and their speed on the inclined slope detected and that one determines the dynamic contact angle from the shape of the surface of the draining liquid.
    For this
  2. 2 pages drawings
DD21718579A 1979-11-28 1979-11-28 Method and device for determining the surface accountability DD147414B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
DD21718579A DD147414B1 (en) 1979-11-28 1979-11-28 Method and device for determining the surface accountability

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DD21718579A DD147414B1 (en) 1979-11-28 1979-11-28 Method and device for determining the surface accountability

Publications (2)

Publication Number Publication Date
DD147414A1 DD147414A1 (en) 1981-04-01
DD147414B1 true DD147414B1 (en) 1988-07-27

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
DD21718579A DD147414B1 (en) 1979-11-28 1979-11-28 Method and device for determining the surface accountability

Country Status (1)

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DD (1) DD147414B1 (en)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4970893A (en) * 1990-02-27 1990-11-20 Reid Philip L Tilt angle tester
FR2721399B1 (en) * 1994-06-17 1996-08-14 Kodak Pathe Method and device for determining the limits of dynamic wettability of a support.
CN106018184B (en) * 2016-05-20 2018-08-21 大连理工大学 The experimental provision of dynamic contact angle is measured under a kind of high temperature and high pressure environment

Also Published As

Publication number Publication date
DD147414A1 (en) 1981-04-01

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