JPH1048116A - Solution viscosity-measuring apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable automatic measurement by a method wherein a solution sent by a dispensing means is sucked up from a solution reservoir part and a negative state of a space above a liquid level raised is released to detect upper and lower marked lines of a viscosity measuring tube with a sensor. SOLUTION: This solution viscosity measuring apparatus has a dispenser 4 which measures and sends a specified amount of a solution and a viscosity measuring tube 6 and a reference liquid container is connected to the dispenser 4. The viscosity measuring tube 6 comprises first, second and third tubes 12, 14 and 16 and the first tube 12 is made to communicate with the second tube 14 by a first U-shaped bottom part. A bulged liquid reservoir part 22 is formed on the bottom part side of the first tube 12. An upper open end of the first tube 12 is connected to the dispenser 4 through a line 26 opened to the atmospheric air. A closed space is arranged at the upper end of the third tube 16 is connected to a suction release changeover valve 36 as negative pressure releasing means. A liquid sensor is mounted on the bottom part of the second tube 14 and detects whether a liquid is left or not in the bottom part of the viscosity measuring tube 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solution viscosity measuring device capable of automatically measuring the viscosity of a solution such as a vinyl chloride resin solution.

[0002]

2. Description of the Related Art As a method for measuring the viscosity of a solution, the Ostwald method is known.

In this method, first, a solution is poured into a substantially U-shaped viscosity measuring tube. Next, the liquid level of the solution stored in the bottom is pulled up above the upper mark of the tube by sucking from the one open end of the tube. Next, the suction is released, the time required for the liquid surface to pass from the upper mark to the lower mark is measured by a stopwatch or the like, and the viscosity of the solution is calculated based on the measured time.

[0004]

However, in the conventional method, since the measurement of the liquid level falling from the upper mark to the lower mark is performed by a human, the measurement error is large, and the viscosity of the solution is obtained with high accuracy. It was difficult.

In the measurement, it is necessary to wash the inner surface of the viscosity measuring tube in advance, and the washing has been performed by a human. For this reason, it took time to measure the viscosity and was not economical. In particular, in the step of producing a vinyl chloride resin, viscosity measurement is an indispensable step in order to keep the quality of vinyl chloride as a product constant, and automation of the operation has been required.

The present invention has been made in view of such circumstances, and has as its object to provide a solution viscosity measuring device capable of automatically measuring the viscosity of a solution.

[0007]

A solution viscosity measuring apparatus according to the present invention comprises a dispensing means for measuring a predetermined amount of a solution and sending the solution, and a solution reservoir into which the solution sent by the dispensing means enters. A viscosity measurement tube having an upper mark line and a lower mark line formed therein, and suction means for raising the liquid level of the solution stored in the solution reservoir of the viscosity measurement tube to above the upper mark line. A negative pressure releasing means for releasing the negative pressure state of the space above the liquid surface of the solution pulled up by the suction means and allowing the liquid surface to drop in a free falling state, and at the positions of the upper and lower marking lines. An upper mark sensor and a lower mark sensor for detecting that the liquid level has come, and a time when the liquid level is dropped from the upper mark to the lower mark by an output signal from both sensors, and connected to the two sensors. Control means for measuring the

[0008] An outlet may be formed at the bottom of the viscosity measuring tube.

It is preferable that a waste liquid line, a waste liquid pump and a waste liquid tank are connected to the outlet. An electromagnetic valve may be attached to the waste liquid line.

The suction means is, for example, a vacuum generator.

The negative pressure releasing means is, for example, a suction release switching valve.

Preferably, the dispensing means is capable of injecting a liquid for cleaning the inner wall of the measuring tube from the dispensing means to the viscosity measuring tube. In this viscosity measuring tube,
It is preferable that an air blowing means for forcibly dropping the liquid surface after sucking up the liquid for cleaning is provided. The liquid for washing is discharged through a waste liquid line. The liquid for washing is preferably the solution itself to be measured or the solvent of the solution.

It is preferable that the viscosity measuring tube is provided with a liquid sensor for detecting whether or not a liquid exists at the bottom of the tube. Further, it is preferable that an overflow sensor for detecting overflow of the liquid from the tube is mounted near the open end of the viscosity measuring tube. After a series of measurements is completed and before the next measurement is started, it is preferable that the viscosity measuring tube is filled with a liquid for cleaning up to a position below the overflow sensor.

According to the solution viscosity measuring apparatus of the present invention, it is possible to automatically measure the viscosity of a solution.
For this reason, while improving the accuracy of the measurement of the viscosity of the solution,
Labor saving can be achieved by automating work. Also,
It is also possible to automatically supply a liquid for cleaning into the viscosity measuring tube, and it is possible to save labor required for cleaning.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an apparatus for measuring a solution viscosity according to the present invention will be described in detail based on an embodiment shown in the drawings.

FIG. 1 is a schematic configuration diagram of an apparatus for measuring a solution viscosity according to an embodiment of the present invention. FIGS. 10 is a flowchart of the automatic measurement of the solution viscosity.

As shown in FIG. 1, a solution viscosity measuring device 2 according to the present embodiment includes a dispenser 4 as a dispensing means for measuring and sending a predetermined amount of a solution, a viscosity measuring tube 6, Having. The sample liquid container 9 and / or the reference liquid container 10 are connected to the dispenser 4. These containers 9 and 10 are mounted on a sample stand not shown. The sample mount may be an XY stage. By using the XY stage, a plurality of sample liquid containers and reference liquid containers are placed thereon, and by moving the stage, the containers connected to the pipetting device 4 can be switched and controlled.

The viscosity measuring tube 6 itself is basically a known Ubbelohde viscometer, but in the present embodiment, as will be described later, various sensors, a suction opening switching valve, a vacuum generating device,
It is configured to be able to automatically measure viscosity by installing a waste liquid line and the like. As shown in FIG. 2, the viscosity measuring tube 6 includes a first tube 12, a second tube 14, and a third tube 16, and the first tube 12 and the second tube 14 are connected to a first U-shaped bottom. It is communicated by 18. The third pipe 16 communicates with a second U-shaped bottom 20 branched from the bottom of the second pipe 14. This viscosity measuring tube 6 is housed in a thermostat 7,
The tube 6 can be maintained at a predetermined temperature. Further, the sample solution container 7 and the reference solution container 10 are installed in a constant temperature bath 8 in order to maintain a predetermined temperature. The temperature of the thermostat is controlled by Coolnics to keep the temperature constant.

A swelling liquid reservoir 22 is formed on the bottom side of the first tube 12. Upper open end 24 of first tube 12
Is open to the atmosphere and is connected to the dispenser 4 via the supply line 26 shown in FIG. As shown in FIG. 2, a waste liquid port 28 is formed in the first U-shaped bottom portion 18, and the waste liquid line 30 shown in FIG. 1 is connected to the waste liquid port 28. The waste liquid line 30 opens and closes at a waste liquid port 28. An electromagnetic valve may be used for opening and closing. In this waste liquid line 30,
The waste liquid pump 32 is connected, and the waste liquid sucked by the waste liquid pump 32 is stored in a waste liquid tank 34.

As shown in FIG. 1, the upper end of the third tube 16 is
The space is a sealable space, and this space is connected to a suction opening switching valve 36 as a negative pressure releasing means. The upper end of the second tube is a sealable space, and is connected to a vacuum generator 38 as suction means. Vacuum generator 3
8 is constituted by, for example, a vacuum pump or a vacuum tank.

As shown in FIG. 2, two continuous bulges are formed at an intermediate position of the second pipe 14, and an upper mark 40 and a lower mark 42 are formed at that portion. It is. An upper mark sensor 44 and a lower mark sensor 46 are mounted on the outer periphery of each mark 40, 42. These sensors 44,
Reference numeral 46 denotes an optical sensor capable of detecting that the liquid surface has reached the positions of the upper mark 40 and the lower mark 42.

A liquid sensor 48 is mounted on the bottom of the second pipe 14. The liquid sensor 48 is a transmission type optical sensor. The liquid sensor 48 can detect whether or not the liquid remains at the bottom of the viscosity measuring tube 6.

Also, near the upper open end of the second pipe 14,
An overflow sensor 50 is mounted. The sensor 50 can detect the liquid level so as to prevent the liquid from overflowing from the open end of the first pipe 12. Also, the third
At an intermediate position of the pipe 16, an infusion liquid overflow sensor 5 is provided.
2 is installed. The sensor 52 can detect the liquid level so as to prevent the liquid from entering the inside of the third pipe 16 too much. These sensors 50 and 52 are also transmission type optical sensors.

These sensors 44, 46, 48, 50, 5
2 is output from the optical sensor amplifier 58 to the control device 54.
Is input to As shown in FIG. 1, the control device 54 controls the dispenser 4, the waste liquid pump 32, the vacuum generator 38 and the suction opening switching valve 36 based on the output signals from these sensors.

Next, a method of using the solution viscosity measuring device according to the present embodiment will be described with reference to FIGS.

First, preprocessing is performed in step S1 shown in FIG. In the pretreatment, water is poured into the thermostats 7 and 8 shown in FIG. 1 and most of the viscosity measurement tube 6 is submerged in the thermostat 7. Further, the sample liquid container 9 and most of the reference liquid container are submerged in the thermostat 8. The upper open end of the first tube 12 of the measuring tube 6 is open to the atmosphere above the constant temperature bath 7.

Next, in step S2, the power of the measuring device is turned on. The viscosity measuring tube 6 is maintained at a predetermined temperature by a thermostat 7 shown in FIG. In the present embodiment, the predetermined temperature is 30
± 0.1 ° C. In step S3, the water temperature of the thermostatic bath 7 is checked, and only when the temperature is 30 ± 0.1 ° C., the solution inside the viscosity measuring tube 6 is drained through the waste liquid line 30 in step S4. At that time, the control device 54
The pump 32 is driven to drain the waste liquid into the waste liquid tank 34. If the mode is set to the manual mode in step S5, the waste liquid pump switch is manually turned on in step S6. In the case of the single mode, the waste liquid switch may be pressed in step S7. Note that the manual mode is a mode in which all operations of each step such as injection of a sample or a reference liquid, washing of the viscosity measuring tube 6, and waste liquid are manually operated. The single mode is a mode in which the operation of each step such as injection of a sample or a reference liquid, cleaning of the viscosity measuring tube 6, and waste liquid is performed by pressing each switch.

Next, in step S8, the remaining amount of the solution is detected by the liquid sensor 48 shown in FIG. 2, and if there is a remaining amount, the pump 32 is continuously operated. At that time, pump 3
If the remaining amount is detected by the sensor 48 even after the operation time of 2 has passed for 120 seconds, the line is clogged or the sensor is abnormal. In this case, an alarm is generated by the alarm means. Let it. As an alarm,
The sound is preferably an alarm sound, but may be another signal. Then, in the case of the single mode, if the alarm is reset, continuous operation (automatic operation) becomes possible, and in the manual mode, the operation is stopped by the reset.

If it is determined in step S8 that there is no remaining amount, then in step S9, a reference solution container 10 containing the reference solution shown in FIG. The sample liquid container 9 is set. In this embodiment, a vinyl chloride resin solution is used as a sample solution, and cyclohexanone used as a solvent of the vinyl chloride resin solution is used as a reference solution (blank). Note that nitrobenzene may be directly used as the reference solution, but nitrobenzene requires care in handling in terms of occupational health. Therefore, in this embodiment, cyclohexanone is used, and the specific viscosity is converted to the case where nitrobenzene is used as the solvent.

Next, in steps S10 and S11 shown in FIG. 6, the mode is set to continuous (automatic operation mode), and the sample injection switch is turned on. Accordingly, the following operation is automatically performed by the apparatus.

In step S12, the control device 54 shown in FIG. 1 sends a drive signal to the dispenser 4, and the dispenser 4 is operated.
First, 5 ml of the reference liquid is injected into the viscosity measuring tube 6. Next, in step S13, the liquid sensor 48 shown in FIG.
To detect whether the liquid is normally stored at the bottom. If the liquid is not sensed, there is some abnormality, and in that case, the control device 54 operates to stop the operation of the device. An alarm may be generated at the same time.

If a liquid is detected, step S14
Then, the number of times of liquid injection is measured. If the number is less than two, steps S12, S13, and S14 are repeated. When it is three times, the process goes to step S15, and a drive signal is sent from the control device 54 shown in FIG. 1 to the solenoid valve and the waste liquid pump 32 to send the liquid in the pipe 6 to the waste liquid tank 34.

Next, at step S16, the remaining amount of liquid is confirmed by the sensor 48 shown in FIG.
If the liquid remains even after 0 seconds, it is considered that there is an abnormality, and an alarm is generated. If the alarm is reset, continuous operation will continue. When there is no remaining amount of the liquid, in step S17, a drive signal is sent from the control device 54 shown in FIG.
Thus, 5 ml of the reference liquid is injected into the viscosity measuring tube 6. FIG. 2 shows the liquid level 56 in the normal state. As shown in FIG. 2, in the normal state, the liquid is sensed by the sensor 48,
The infusion liquid overflow sensor 52 does not sense the liquid level.

Next, at step S18 shown in FIG. 6, the liquid is sensed by the sensor 48 shown in FIG. 2. If the liquid is not sensed, it is abnormal, and in that case, the operation is stopped. The alarm sounds. If the liquid is detected, then in step S19, the liquid is detected by the infusion liquid overflow sensor 52 shown in FIG. If a liquid is detected, the operation is stopped and an alarm sounds in such a case because the liquid is overfilled. Only in the normal state shown in FIG. 2 and not in the over-injection state, in step S20 shown in FIG. 7, the switching valve 36 is driven by the control device 54 shown in FIG. 1 to seal the upper space of the second pipe 14. Space.

Next, in step S21 shown in FIG. 7, a drive signal is sent from the control device 54 shown in FIG. 1 to the vacuum generator 38, and the upper space of the second pipe 14 is sucked to be in a negative pressure state. Therefore, the liquid level in the second pipe 14 rises.
Moreover, since a member for promoting the capillary phenomenon is mounted on the bottom of the second tube 14, as shown in FIG.
At 4, the liquid level 56 rises, especially above the upper front line 40. After maintaining this state for 4 seconds, FIG.
In step S22 shown in FIG. 1, a drive signal is sent from the control device 54 shown in FIG. 1 to the switching valve 36 to open the upper space of the third pipe 16 and drop the liquid level 56 shown in FIG. At this time, it is preferable that air is forcibly blown into the upper space of the second pipe 14 from the switching valve 36 so that the liquid surface 56 is forcibly dropped by air pressure while being superimposed on the action of gravity.

Next, at step S23 shown in FIG. 7, a drive signal is sent from the control device 54 shown in FIG. 1 to the waste liquid pump 32, and the liquid in the pipe 6 is discharged. Next, in step S24 shown in FIG. 7, in the same manner as in step S16 shown in FIG. 6, the remaining amount of the liquid is detected, and if there is no remaining amount, the process goes to step S25 to measure the number of times of washing. In this embodiment,
Since the cleaning is performed with the reference solution and the number of times of the cleaning is set to four times (any number of times is possible), if it is less than four times, the step S
The cleaning process from 17 to S25 is repeated. At the fifth time,
Going to step S16, the reference solution is injected into the measuring tube 6 as shown in FIG. 2 in the same manner as in step S17 shown in FIG. Next, in steps S27 and S28, as in steps S18 and S19 shown in FIG. 6, liquid injection confirmation and over-injection are detected.

Next, in step S29, the state shown in FIG. 2 is maintained for 5 minutes, and the temperature of the liquid is maintained at 30 ° C. by the constant temperature bath 7 shown in FIG. Next, in step S30 shown in FIG. 8, the switching valve 36 is driven by the control device 54 shown in FIG. 1 to make the upper space of the second pipe 14 a closed space.

Next, in step S31 shown in FIG. 8, a drive signal is sent from the control device 54 shown in FIG. 1 to the vacuum generator 38, and the upper space of the second pipe 14 is sucked to be in a negative pressure state. Therefore, the liquid level in the second pipe 14 rises.
Moreover, since a member for promoting the capillary phenomenon is mounted on the bottom of the second tube 14, as shown in FIG.
At 4, the liquid level 56 rises, especially above the upper front line 40. After maintaining this state for 2 seconds, FIG.
In step S32 shown in FIG. 1, a drive signal is sent from the control device 54 shown in FIG. 1 to the switching valve 36 to open the upper space of the third pipe 16, and the liquid level 56 shown in FIG. At this time, the sensors 44 and 46 shown in FIG.
The time during which the liquid level 56 passes between the upper mark 40 and the lower mark 42 is measured. The measurement of the time is performed by a timer or the like built in the control device 54 shown in FIG. 1, and the measurement is preferably performed in units of 1/100 second.

Next, in step S33, the number of measurements is counted, and in the first measurement, steps S30 to S33 are repeated, and the second measurement is performed. When the second measurement is completed, the result of the first measurement is compared with the result of the second measurement in step S34.
If it is within seconds, the process proceeds to the automatic calculation process of step S37. If the time is within 1/10 second, it is considered that the measurement is reliable. In that case, the third measurement is omitted.

If it is longer than 1/10 second, it is determined whether or not the difference is within 2/10 seconds. If it is within 2/10 seconds, then in step S36, the number of measurements is determined, and if the number of measurements is two, steps S30 to S33
Is repeated again, and the third measurement is performed. Step S35
In the case where the difference is 2/10 or more, it is considered that the measurement is not reproducible and there is an abnormality.
An alarm is generated by the control device 54.

When the third measurement is completed, the process proceeds from step S33 to step S35, where the maximum value and the minimum value of the three measurement time results are compared, and whether or not the difference is within 2/10 seconds is determined. to decide. If not, the next step S
Go to 36 and S37. If not, raise an alarm.

In steps S12 to S36,
Although the reference solution (blank) was used as the solution, the same procedure as described above was applied to the sample solution to be measured in step S1.
Steps S2 to S36 are performed, and step S37 shown in FIG.
Is automatically calculated by the controller 54. With automatic calculation,
For example, the following calculation formula is executed to determine the specific viscosity.

That is, a sample solution (cyclohexanone solution of vinyl chloride resin) with respect to the cyclohexanone standard solution
Specific viscosity eta ₁ of is calculated by _{η 1 = A / B-1} . Here, A is the arithmetic average value of the drop seconds (measurement time result) when the sample solution is used, and B is the arithmetic average value of the drop seconds (measurement time result) when the reference solution is used.

Next, in the automatic calculation process, the specific viscosity η ₂ when nitrobenzene is used as the solvent is determined by a regression equation for the correlation between η _s and η ₁ which is separately determined.

Next, in step S38 shown in FIG. 8, data such as a measurement result and a calculation result is output on paper or a screen. Thereafter, in step S39, a drive signal is sent from the control device 54 shown in FIG. 1 to the pump 32, and the liquid in the measuring tube 6 is discharged.

Next, in step S40 shown in FIG. 9, the remaining amount of liquid is confirmed by the sensor 48 shown in FIG. 1, and if there is a remaining amount of liquid even after 120 seconds of the pump operation time, there is an abnormality. An alarm is generated. If the alarm is reset, continuous operation will continue. If there is no remaining liquid, in step S41,
A buzzer or the like sounds at the end of measurement.

Next, in step S42, the number of measurements is measured, and if less than the predetermined number of measurements, the processing from step S9 is repeated. When the predetermined number of measurements have been completed, in step S43, a reference liquid (also a cleaning liquid, which is referred to as a blank in the figure) container is placed on the sample stand, and a line is set. Next, in step S44, the mode is set to continuous, and in step S45, the cleaning liquid injection switch is pressed. Thereafter, in step S46, a drive signal is automatically transmitted from the control device 54 shown in FIG. 1 to the dispenser 4, and the dispenser 4 injects 5 ml of a reference solution as a cleaning liquid into the measuring tube 6. Is done. Then, steps S47 and S48
Then, in the same manner as in steps S18 and S19 shown in FIG. 6, confirmation of liquid injection and detection of excessive injection are performed.

Thereafter, in step S49 shown in FIG. 10, the switching valve 36 is driven by the control device 54 shown in FIG.
The upper space of the third pipe 16 is a closed space.

Next, in step S50 shown in FIG.
A drive signal is sent from the control device 54 shown in FIG. 1 to the vacuum generator 38, and the upper space of the second pipe 14 is sucked to be in a negative pressure state. Therefore, the liquid level in the second pipe 14 rises.
Moreover, since a member that promotes the capillary phenomenon is attached to the bottom of the second tube 14, as shown in FIG.
In the pipe 14, in particular, the liquid level 56 rises and the upper front line 40
Will be exceeded. After keeping this state for 4 seconds,
A drive signal is sent from the control device 54 shown in FIG. 1 to the switching valve 36 to open the upper space of the third pipe 16, and
6 is dropped. At this time, it is preferable that air is forcibly blown into the upper space of the second pipe 14 from the switching valve 36 and the liquid surface 56 is forcibly dropped by air pressure in superposition with the action of gravity.

Next, in step S51, the number of times of cleaning is measured. In the present embodiment, the cleaning is performed with the reference solution, and the number of times of cleaning is set to two (any number of times).
In the second time, the cleaning process in step S50 is repeated. At the second time, the process goes to step S52, and the liquid in the measuring tube 6 is discharged in the same manner as described above.

Next, in step S53, similarly to step S24 shown in FIG. 7, it is determined whether or not the liquid remains in the measuring tube 6, and only when the liquid does not remain, the process proceeds to step S54. In step S54, by pressing the liquid injection switch, the control device 54 shown in FIG. 1 sends a drive signal to the dispenser 4 in step S55, and 15 ml of the cleaning liquid (reference Same as liquid)
Is sent. FIG. 4 shows a state in which 15 ml has been injected.

Thereafter, in step S56, a signal is sent from the control device 54 shown in FIG. 1 to the vacuum generator 38 to put the upper space of the third pipe 16 into a negative pressure state and raise the liquid level in the second pipe 14. Then, the liquid level is stopped at a position beyond the infusion liquid overflow sensor 52. The control is performed by the control device 54 based on the output signal from the sensor 52.

Thereafter, in step S57 shown in FIG. 10, a drive signal is sent from the control device 54 shown in FIG. 1 to the dispenser 4, and 10 ml of the washing liquid is further injected into the measuring tube 6. In this state, almost all of the inside of the first tube 12, the second tube 14, and the third tube in the measurement tube 6 will be filled with the cleaning liquid, and the next measurement will be awaited in this state. Finally, in step S58, the power of the apparatus is turned off.

The present invention is not limited to the above-described embodiment, but can be variously modified within the scope of the present invention.

For example, the type of solution measured by the solution viscosity measuring device according to the present invention is not particularly limited, and various types can be used.

[0056]

As described above, according to the apparatus for measuring the viscosity of a solution according to the present invention, it is possible to automatically measure the viscosity of a solution. For this reason, the accuracy of the measurement of the viscosity of the solution can be improved, and labor can be saved by automating the operation. Further, a liquid for cleaning can be automatically supplied into the viscosity measuring tube, and labor required for cleaning can be saved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an apparatus for measuring a solution viscosity according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing a change in liquid level in the process of automatic measurement of solution viscosity.

FIG. 3 is a schematic diagram showing a change in liquid level in the process of automatic measurement of solution viscosity.

FIG. 4 is a schematic diagram showing a change in liquid level in the process of automatic measurement of solution viscosity.

FIG. 5 is a flowchart of the automatic measurement of the solution viscosity.

FIG. 6 is a continuation of the flowchart of FIG. 5;

FIG. 7 is a continuation of the flowchart of FIG. 6;

FIG. 8 is a continuation of the flowchart of FIG. 7;

FIG. 9 is a continuation of the flowchart of FIG. 8;

FIG. 10 is a flowchart continued from FIG. 9;

[Explanation of symbols]

 2 solution measuring device 4 dispenser (dispensing means) 6 viscosity measuring tube 8 constant temperature bath 9 sample liquid container 10 reference liquid container 12 first tube 14 second tube 16 third Pipe 22: Solution reservoir 36: Suction release switching valve (negative pressure release means) 38: Vacuum generator (suction means) 40: Upper mark 42: Lower mark 44: Upper mark sensor 46: Lower mark sensor 54 … Control device

Claims (1)

[Claims] 1. A dispensing means for measuring and sending a predetermined amount of a solution, and a solution reservoir into which the solution sent by the dispensing means enters, and an upper mark line and a lower mark line are formed. A viscosity measuring tube, a suction means for raising the liquid surface of the solution stored in the solution reservoir of the viscosity measuring tube to above the upper mark, and a liquid level of the solution pulled by the suction means. Negative pressure releasing means for releasing the negative pressure state of the space and dropping the liquid surface in a free falling state, an upper mark sensor and a lower sensor for detecting that the liquid surface has come to the positions of the upper mark line and the lower mark line A solution viscosity measuring device, comprising: a marked line sensor; and control means connected to the two sensors and configured to measure a time required for a liquid surface to fall from an upper marked line to a lower marked line based on output signals from the both sensors.