JPH05273108A - Dynamic surface tension measuring method and device - Google Patents

Abstract

PURPOSE:To simply measure the dynamic surface tension of a liquid sample under the preset conditions near various operating states of the liquid sample by adding a very simple improvement to the conventional vertical plate method. CONSTITUTION:A solid plate 3 is dipped and suspended in a sample liquid 2 filled in a container 1 while tensile force P is applied upward, the surface tension is measured based on the magnitude of the tensile force P, the weight of the solid plate 3, and the magnitude of the buoyancy applied to the solid plate 3, and a liquid injection port 4 is provided on the container 1. The sample liquid 2 is continuously introduced through the liquid injection port 4, and the surface tension on the surface is measured while the sample liquid 2 is overflowed from the container 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for measuring the surface tension of a liquid sample, and more particularly to a method and apparatus for measuring the dynamic surface tension of a liquid containing a surfactant.

[0002]

2. Description of the Related Art For example, a surfactant may be mixed in order to optimize the coating characteristics of a coating liquid. When it is attempted to measure the relationship between the mixing ratio and the surface tension, for example, "New Experimental Chemistry Course, Volume 18, Interfaces and Colloids "(Maruzen Co., Ltd., pp.69-90 (1977))
Capillary rise method, static drop method, static bubble method, hanging drop method, drop weight method, ring method, vertical plate method (Wilhelmy).
Method), etc., and as a dynamic surface tension measuring method, as described in the above-mentioned document, a vibration jet method, a meniscus dropping method, a maximum bubble pressure method, etc. are also known. A liquid film destruction method as described in JP-A-3-20640 is known.

[0003]

By the way, the coating liquid containing the surfactant as exemplified above usually has a dynamic surface tension different from the static surface tension in the use state. Moreover, the dynamic surface tension also differs depending on the kind of the mixed surfactant. Therefore, in order to measure the surface tension as close as possible to the condition of use and design the optimum coating liquid, you can easily change the dynamic conditions and easily adjust the dynamic surface tension of the liquid sample under various conditions. There is a need for a method and apparatus that can measure.

However, the former method described above is a static surface tension measuring method, and it is impossible to measure a dynamic surface tension satisfying such a demand. In addition, the latter method has problems that the device is large-scale, a large amount of sample liquid is required, and measurement conditions cannot be changed to perform measurement.

The present invention has been made in view of such a situation, and an object thereof is to make a liquid by making a very simple addition and improvement to a vertical plate method which is a conventional simple static surface tension measuring method. It is an object of the present invention to provide a method and a device capable of easily measuring the dynamic surface tension of a sample by setting the conditions close to various usage conditions.

[0006]

[Means for Solving the Problems] As a result of various studies to solve the above-mentioned problems, an injection port is provided in a container for holding a liquid sample in the vertical plate method, and the sample liquid is continuously supplied from this injection port. It is possible to measure dynamic surface tension easily by using a small amount of sample liquid by introducing the sample liquid, overflowing the sample liquid from the upper end of the container, constantly appearing a new surface, and measuring the surface tension by the vertical plate method. The present invention has been completed by finding the above.

That is, the method for measuring the dynamic surface tension of the present invention which achieves the above-mentioned object, is to immerse and suspend a solid plate by applying upward tension to the sample liquid filled in the container,
In the method of measuring the surface tension from the magnitude of the tension, the weight of the solid plate, and the magnitude of the buoyancy applied to the solid plate, an injection port is provided in the container, and the sample liquid is supplied at a constant flow rate from the injection port. Is continuously introduced, and the surface tension of the surface of the sample liquid is measured while overflowing the sample liquid from the container.

Further, the dynamic surface tension measuring device of the present invention is
In a surface tension measuring device consisting of a container having an open upper end for containing a sample liquid and a solid plate suspended by applying a tension upward and immersed in the sample liquid in the container, a liquid injection for introducing the sample liquid into the container It is characterized in that it is provided with a mouth and a fixed-quantity discharge means for continuously discharging the sample liquid at a constant flow rate to the liquid injection hole.

In this case, the container is cylindrical, the upper end thereof is opened by a horizontal circular edge, and the liquid injection port is provided at the center of the bottom, or the container is long. It has a rectangular shape and has an opening on one side that is long.
It is desirable that the liquid injection port is provided on one of the short side surfaces of the sample so that the sample liquid overflows in one direction from the upper short edge on the opposite side.

[0010]

In the present invention, for example, commercially available Wilhel
The my-type surface tensiometer container is provided with an injection port, and the sample liquid is continuously introduced from this injection port at a constant flow rate, and the surface tension of the surface is measured while the sample liquid overflows from the container. Therefore, a new surface of the sample liquid always appears, its dynamic surface tension can be measured, and the dynamic surface state of the sample liquid can be evaluated.

[0011]

EXAMPLES First, the conventionally known vertical plate method (Wilhelm) is used.
The principle of measuring the surface tension by the y method) will be briefly described. As shown in the sectional view of FIG. 6, a sample liquid 12 is put in a container 11 such as a Petri dish and has a good wettability with the liquid 12 and a contact angle of 0 ° (this requirement is not always necessary but 0 ° for simplicity. The tip of the plate 13 in FIG.
Tension P is applied to the plate 13 upward. Plate 1
The weight of 3 is M, the immersion depth of the plate 13 is h, the area of the horizontal cross section of the plate 13 is s, the peripheral length of the horizontal cross section of the plate 13 is L, the density of the liquid 12 is ρ, and the surface tension is γ. Then, the upward force (tension + buoyancy) and the downward force (gravity + surface tension) are balanced as in the following equation (1).

P + shρg = Mg + Lγ (1) By modifying this equation (1), the surface tension γ of the sample liquid 12 can be obtained by the equation (2).

Γ = (P + shρg−Mg) / L (2) As an actual measurement method, for example, a relationship between h and P ₀ is obtained for a standard liquid (for example, pure water) having a surface tension γ _0. Next, the tension P at the immersion depth h is calculated for the liquid to be measured, and the surface tension γ of the liquid is calculated by the following equation (3) with the same buoyancy.

Γ = γ ₀ − (P ₀ −P) / L (3) The surface tension measured by the above vertical plate method is the static surface tension when the liquid sample is stationary. .. In the present invention, the vertical plate method is modified so that the dynamic surface tension can be measured.

FIG. 1 is a conceptual view of an apparatus for carrying out the method for measuring the dynamic surface tension according to the present invention, in which a container 1 containing a sample liquid 2 and a plate 2 having good wettability with the liquid 2 are immersed in the liquid 2. The use of 3 is the same as in the case of the conventional vertical plate method. In the present invention, the sample liquid 2 is continuously introduced into the container 1 from the liquid injection port 4 at a predetermined flow rate, a new surface is constantly made to appear while the liquid 2 overflows from the upper end of the container 1, and the surface tension of the surface is measured. I am trying. Therefore, the sample liquid 2 such as ink contained in the bottle 6 is continuously sent to the liquid injection port 4 through the pipe 7 by the pump 5. The flow rate is adjusted by the flow rate control valve 8 provided in the pipe 7. Since the surfactant in the bottle 6 is concentrated on the surface in a stationary state, the sample liquid 2 of the prepared concentration may not be sent depending on the height of the inlet of the pipe 7, so the sample in the bottle 6 may not be sent. The liquid 2 is constantly stirred by the stirring device 10 to have a uniform concentration.

By doing so, the liquid 2 continues to flow in the container 1, and depending on the type of the liquid 2, the liquid 2 is mixed almost uniformly and it becomes difficult for molecules of the surfactant and the like to concentrate on the surface thereof, and the plate The magnitude of the surface tension applied to 3 is different from the value when the liquid 2 is at rest (generally smaller), and the value changes depending on the flow rate of the liquid 2. In addition, in order to measure the surface tension stably, it is desirable that the upper end of the container 1 be horizontal and open with a smooth edge.

As a specific example, a commercially available Wilhelmy type surface tensiometer container was provided with a liquid injection port arranged as shown in FIG. 1, and water containing a surfactant was sent using a constant-quantity discharge device. After the sample liquid overflows from the container, Wilhelmy
The plate (plate 3 in FIG. 1) was immersed in the solution and the dynamic surface tension was measured. The measurement results are shown in FIGS. 2 and 3. FIG. 2 shows the surface tension with respect to the flow rate when Perex OT-P (P-OTP) of Kao Corporation was added to pure water as the surfactant at the ratio shown in FIG.
Is a 3M Company's Florard FC-95 as a surfactant.
The same surface tension is shown when (FC-95) is added to pure water in the ratio shown in the figure, and the surface tension of pure water is also shown in each case. From FIGS. 2 and 3, in the case of any of the surfactants, the dynamic surface tension is large with respect to the static surface tension (flow rate: 0 ml / min) and depends on the supply rate of the sample liquid. It can be seen that the faster the surface tension, the higher the dynamic surface tension. Moreover, the ratio depending on the feed rate varies depending on the type of the surfactant, and when the surfactant of FIG. 3 is used as compared with FIG. 2, the dynamic surface tension increases immediately as the velocity increases ( It can be predicted that it is not very suitable for coating (actually it was).

In the apparatus for measuring the dynamic surface tension according to the present invention, it is desirable that the sample liquid overflowing from the container is as symmetrical as possible, a new surface is always formed, and the reproducibility of the measurement is stable. For that purpose, as shown in the sectional view of FIG. 4, as the container 1 ′, a container having a cylindrical upper end opened by a horizontal circular edge is used, and the injection port 4 is provided at the center of the bottom of the container 1 ′. It is desirable to use the one provided in.

When it is necessary to perform the measurement under the condition that the sample liquid 2 on the measurement surface flows in one direction, as shown in the sectional view of FIG. It is desirable to use one that is open on one side surface, to which the sample liquid 2 is supplied from one short side surface side so that the sample liquid 2 overflows in one direction from the upper short edge on the opposite side. In this case, in order to uniformly mix the supplied sample liquid 2, it is desirable to provide a mixing means 9 for causing the liquid to meander up and down as shown in the figure to eliminate the turbulent flow on the liquid injection port 4 side.

Although the embodiments of the method and apparatus for measuring the dynamic surface tension of the present invention have been described above, the present invention is not limited to these embodiments and various modifications can be made. For example, the required sample solution can be further reduced by circulating the sample liquid.

[0021]

As is apparent from the above description, according to the dynamic surface tension measuring method and apparatus of the present invention, commercially available Wi is used.
The container of the lhelmy-type surface tensiometer is simply provided with an injection port,
By sending the sample liquid continuously at a constant flow rate, with a simple device, it is possible to accurately and easily with various devices at various flow rates under conditions close to the usage condition without using much sample solution. The dynamic surface tension of various sample liquids can be measured.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of an apparatus for carrying out a method for measuring a dynamic surface tension according to the present invention.

FIG. 2 is a diagram showing an example of measurement results obtained by the measurement method of the present invention.

FIG. 3 is a diagram showing measurement results of another example.

FIG. 4 is a cross-sectional view of one embodiment of the apparatus for measuring the dynamic surface tension of the present invention.

FIG. 5 is a sectional view of a device for measuring a dynamic surface tension according to another embodiment.

FIG. 6 is a sectional view for explaining a principle of measuring surface tension by a conventional vertical plate method.

[Explanation of symbols]

 1, 1 ', 1 ", 11 ... Containers 2, 12 ... Sample liquid 3, 13 ... Plate 4 ... Injection port 5 ... Pump 6 ... Bottle 7 ... Piping 8 ... Flow rate control valve 9 ... Mixing means 10 ... Stirring device

Claims (4)

[Claims] 1. A solid plate is immersed in and suspended from a sample liquid filled in a container by applying a tension to the sample liquid, the magnitude of the tension, the weight of the solid plate, and the magnitude of buoyancy applied to the solid plate. From the above, in the method of measuring the surface tension, the container is provided with an injection port, the sample liquid is continuously introduced from this injection port at a constant flow rate, and the surface of the surface of the sample liquid is overflowed from the container. A method for measuring dynamic surface tension, which comprises measuring tension. 2. A surface tension measuring device comprising a container having an open upper end for containing a sample liquid, and a solid plate suspended by applying upward tension and immersed in the sample liquid in the container, wherein the sample is contained in the container. A dynamic surface tension measuring device comprising: a liquid injection port for introducing a liquid; and a constant volume discharge means for continuously discharging the sample liquid at a constant flow rate to the liquid injection port. 3. The container according to claim 2, wherein the container is cylindrical, the upper end of which is opened by a horizontal circular edge, and the liquid injection port is provided at the center of the bottom of the container. Surface tension measuring device. 4. The container has a rectangular parallelepiped shape and is opened on one long side surface thereof, the liquid injection port is provided on one short side surface side thereof, and the sample is provided in one direction from an upper short edge on the opposite side. The dynamic surface tension measuring device according to claim 2, wherein the liquid overflows.