JPH04116450A - Viscosimeter for molten plastic - Google Patents

Abstract

PURPOSE:To correctly adjust the driving conditions at the extruding time by making actually the same measuring means of viscosimeters of an on-line method and an off-line method and usable in both viscosimeters. CONSTITUTION:The viscosity is measured with use of the same data as supplied in the production line by a viscosimeter A of an off-line method. Then, the viscosity in the production line is measured by a viscosimeter B of an on-line method. At this time, the driving conditions of the production line are adjusted for production with reference to the measured values of the viscosimeter A, and moreover, adjusted with use of the measured values of the viscosimeter B. Measuring means 2, 2' of the viscosimeters are actually the same, and therefore the measured values of the viscosimeter A nearly coincide with those values in the production line. Accordingly, the measured values of the off-line method can be used as they are in the on-line method, and various driving conditions at the extruding time can be correctly adjusted.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention is utilized in the technical field of viscometers, and in particular relates to viscometers for molten plastics.

(Prior art) Such a viscometer is well known, for example,
This method is disclosed in Japanese Patent Application Laid-open No. 1-34532, Japanese Patent Application Laid-Open No. 1-292233, and Japanese Patent Application Laid-Open No. 2-55933.

Regarding the viscosity of a viscous material, as is well known, the relationship between the shear velocity Q and the viscosity η, which is a function of this shear velocity, is an important factor that affects the flow pattern and heat generation. In other words, the flow state of the molten synthetic resin in the mold, for example, is influenced by the data η characteristic described above, and the mold setting H1
Sometimes it is necessary to know the properties of the synthetic resin used. Furthermore, on the production line, it is necessary to perform quality control by measuring the characteristic values of materials that are actually in flow, such as synthetic resins. For this reason, it is possible to measure the viscosity by installing a viscosity measuring means in the extruder, that is, in the middle of the production line, without extruding the molten plastic, or to measure the viscosity with a separate viscosity 31, that is, offline. Either one of these was adopted.

Now, in the already mentioned Japanese Patent Publication No. 62-34.532, an example is described in which viscosity is measured and controlled online in a production line, and in this, the pressure of the plastic melt is converted into heat. Therefore, it is common practice to control the pressure by measuring the temperature of the melt.

In this example, the 'rHA degree dependence of viscosity is also mentioned, but the off-line viscometer used to obtain the basic data is the viscosity d1 specified in ASTM D 1.238-65T, and the material is When heating,
This is a type of cylinder in which solid materials are put into the cylinder 1-7, the cylinder is covered with a flange, and the cylinder is heated from the outside. When a material heated in this way is extruded from a gear pillar, the material reaches the capillary with almost no shear history, so the flow behavior is different from that of a material plasticized by a screw extruder. It is a thixotropic negative.

(Problems to be Solved by the Invention) The problems to be solved by the present invention are the following problems encountered in conventional viscometers as described above.

(1) In the online system where 51 measurement means are installed on the production line, it is necessary to fill the entire production machine with data even for #11 pieces, and a large amount of data is required even though the data of n-η is not output. , it is necessary to heat this large amount of materials, which wastes a lot of materials, heat, and time.

(2) Only a small amount of data is required for viscosity 51 in the offline method, but d1711 [
J conditions and the conditions of materials being produced on the production line do not necessarily match, and quality control is far from perfect.

(Means for solving the problem) The first invention of this application is shown in FIGS. 1, 2, 3, and 4.
This will be explained with reference to the figures and FIG.

Cod liver oil j means 2 with viscosity tlA of this invention offline method
and the on-line viscosity i1B measurement ΔIQ means 2 have substantially the same construction. In this invention, "substantially the same" means that a single measuring stage can be selectively attached to either of the viscosity gauges A and B, or that the measuring means 2 and 2' This means whether to use products manufactured based on the same design specifications.

Figure 1 shows an off-line viscosity JIA, in which an S1 measurement means 2 is attached to the data supply means. Figures 4 and 5 are on-line viscometers. Figure 4 shows an extruder on a production line with one if:IAt means 2' installed internally, and Figure 5 shows an on-line viscometer using a switching valve. It is possible to switch between the offline method and the off-line method.

Next, the second invention will be explained with reference to FIGS. 2, 3, J, and 5. Channel 5 in the tip 4a of the extruder 4
Then, the material flow path 4b is branched. The material flow path 4b is centered by the pilot part 7b and connected to the flow path 6b of the switching valve 7 by a bolt 7c. Furthermore, it is centered on the downstream side of the switching valve 7 (j, quantitative supply section block] 51 by the inlet part 15c), and is fastened to the off-line viscometer measuring means 2' by the pole l-15d. In addition, since the "niga branch 1" of the switching valve 7 is connected to the data supply means of the offline viscometer, the measuring stage 2' can be selected from either the online method or the offline method using the switching valve 7. It is something.

To explain the third invention further, in an actual production line, even if an online viscosity H1 is installed to measure the viscosity change over time, what is the total value? The Ill+ temperature is not necessarily constant. Therefore, the difference between the standard temperature and f (measured temperature) is detected, and the difference is compensated for using data collected in advance using an offline viscometer.

The offline viscometer used here is equipped with a material supply means that includes a built-in screw, so when the material is plasticized, sufficient shear is applied to the material, making the properties of the material uniform. At the same time, the molecular entanglement is released to some extent.

Since a screw extruder is actually used on the production line, the properties of the materials are very close to those measured offline.

On the other hand, in the conventional viscometer that uses a plunger to push out the material, the material remains in the cavity without being released from molecular entanglement, as mentioned above.
Therefore, the material flowing through the capillary exhibits thixotropic properties, in which the viscosity decreases in accordance with the degree to which molecules are released from entanglement with each other. In other words, the viscosity behavior is different from that in the online case.

Further, in the fourth invention, a monitor thermometer 19 is disposed immediately before the capillary 3e of the capillary portion 3 (at the top in the figure).

The fifth invention is that the monitor thermometer] 9 is an infrared thermometer.

(Operation) In the first invention of this application, first, the viscosity is measured by an off-line viscometer A using the same material as that to be supplied to the production line. In other words, the Qi η characteristic is measured.

Although melted plastic is often used as the material described here, the material of the present invention is not necessarily limited to plastic. For example, it also includes pitch raw materials used in producing pitch-based carbon fibers.

Then, on the production line, online viscometer B
Measure the viscosity by In this case, production is performed by adjusting various operating conditions on the production line with reference to the t-η characteristics obtained by the offline viscometer A described above, and further adjustments are made using the measured values of the online viscometer B. Since the measuring means 2 and 2' of each viscometer A and B are substantially the same, the open side value measured by the viscometer A in the off-line method almost matches that on the production line.

Next, in the second invention, the switching valve 7 is operated to first connect the measuring means 2' to the data flow path 6a of the offline type viscometer A, so that the offline type viscometer A can be used. do. Then, using this viscometer A, the viscosity is measured 31 times using the same material as that to be supplied to the production line, and the Qi η characteristic is kept open. Next, the switching valve 7 is switched to connect the data passage 6b of the measuring means 2' to the data passage 4b of the online type viscometer B, that is, to connect the data passage 6b of the online type viscometer B to the production line.
to form. Similarly to the first invention, the viscometer A
Production is carried out by adjusting various operating conditions on the production line with reference to the Qi η characteristics determined by the measured values of , and further adjustments are made using the measured values of the viscometer B. In this case as well, since the measuring means 2' is common, accurate adjustment is possible.

Regarding the third invention, as detailed in the examples, the viscosity of the material changes depending on the temperature, so it is necessary to accurately grasp the temperature of the resin passing through the capillary over time during online operation. The data was originally measured using an offline viscometer and then subjected to temperature correction. As a result, even if the open side temperature at online viscosity a4 deviates from the standard temperature, it can be immediately converted to the viscosity value at the standard temperature, and various operating conditions can be adjusted appropriately.

Furthermore, in the fourth invention, a monitor thermometer 19 (infrared thermometer in the fifth invention) is provided just before the capillary 3e, and if an infrared thermometer is used, the temperature of the wall of the conventional vessel can be measured. Unlike the original, it is not only possible to accurately measure the temperature of the material passing through the capillary 3e, but also when the tip of the temperature monitor H419 is placed just in front of the capillary 3e, the temperature measurement section can be used to accurately measure the temperature of the material passing through the capillary 3e. The temperature just in front of the capillary 3e can be accurately measured without installing it protruding into the flow of the capillary. Furthermore, since the temperature measuring section does not protrude into the flow of materials, the flow of materials is not disturbed.

(Example) First, the viscosity i of the Zunawaji offline system in the example of the first invention will be explained with reference to FIG.

FIG. 1 illustrates an offline type viscometer A.

Reference numeral 1 denotes a material supply means, and 8 an extrusion section, in which a screw 8C is rotatably fitted into a cylindrical casing 8a having a hopper 8b formed in the upper part. Casing 8a
A supply path 8d is connected to the lower part of the supply channel 8d. On the other hand screw 8C
A variable speed motor 9 is provided to drive the motor 9, and the output shaft of the motor 9 is connected to the input shaft of the reducer 10 and the coupling 1.
Connected by 1. The reducer 10 is, for example, a helical gear reducer, and its output shaft is connected to the screw 8c to drive it in the direction indicated by the arrow in the figure.

Furthermore, the material supply means extrusion section 8 is provided with heaters 8e, 81, . . . and thermometers 2, 13.

The quantitative supply section 15 of the measuring means 2 is connected to the downstream end (the left end in the figure) of the supply path 8d. The quantitative supply section 15 has its suction [1] connected to the supply path 8d, and its discharge [) connected to the capillary section 3. A variable speed motor 16 is provided to drive the fixed amount supply section 15, and the output shaft of this motor 16 is connected to the drive shaft of the fixed amount supply section 15 by a coupling]7. is tachometer 16
A is provided. As the metering pump 1.5a, an 11-tooth pump is preferable because it is small and precise, but other types of metering pumps may be used.

The capillary part 3 is centered with respect to the outlet of the quantitative supply part 15, and is fastened with a bolt 3b. Furthermore, the capillary part 3 has a pressure gauge connection chamber 3C on its inlet side, and this pressure gauge connection chamber 3C includes a pressure gauge 18 and a temperature monitor H.
19 are connected. [1] A heater 3d is also provided in the cavity portion 3. The downstream side (lower side in the figure) of the pressure side connection chamber 3C is the capillary 3
e is formed, and the extreme end is open to the atmosphere. A control means 26 is provided for controlling the temperature H
112, 13, tachometer] 6a and pressure 3114 OJ
: and 18 are taken in, while command information is input to the heaters 8e and 8f and the motor 16.

In this way, pellets of thermoplastic synthetic resin are supplied from the hopper 8b. Then, it is heated in the casing 8a by the heater 8e, and is fed by the screw 8C while being melted, and reaches the supply path 8d. During this time, the output signals of the thermometers 12 and 13 are input to the control means 26, and the control means 26 controls the heaters 8e and 8f so that these values become the previously input values. Also, tachometer 1
Based on the output signal 68, the control means 26 senses the rotational speed of the motor 16, and is controlled so that the feeding amount of the quantitative supply section 15 is constant. Furthermore, the rotational speed of the screw 8C is controlled so that the pressure indicated by the pressure gauge 14 is approximately constant. That is, the rotation speed of the motor 9 is controlled. Further, a display device 26a is attached to the control means 26.

Then, the control means 26 changes the temperature t″C of a certain thermoplastic synthetic resin and calculates the viscosity η at that time from the relationship between the rotational speed of the quantitative supply pump 15a and the indicated pressure value of the pressure gauge 18. , the curve of shear rate with temperature t'C as a parameter and viscosity η is displayed as 'jl'.
t, 26 a. At this time, the shear velocity t, that is, the amount of material sent out,
A Chi η curve is obtained by varying the rotational speed of a.

Next, the third invention will be explained in detail.

The temperature of the material is determined by the control thermometer 12.13 (even if the temperature is kept constant, the temperature detected by the monitor thermometer 19 is not necessarily the same as the temperature indicated by the control thermometer 12.13). isn't it.

That is, when the supply amount of the quantitative supply section 15 is increased or decreased, the rotational speed of the screw 8C of the extrusion section 8 of the material supply means must also be increased or decreased in proportion to this. When the rotational speed of the screw 8C is increased, the temperature of the sample tends to rise due to frictional heat generation, so in such a case, the monitor temperature is detected to be higher than the temperature of the control thermometer 12, 13.

Increasing the value of Chi in the Chi9 curve means increasing the rotational speed of the screw 8C. Therefore, if the temperature control conditions are constant, it is difficult to actually keep the sample temperature constant, and as shown by the broken line in Figure 6, the shear velocity Qi viscosity 9 curve actually controlled is , where the shear rate Q is small, it is shifted to the low temperature side, and where ψ is large, it is shifted to the high temperature side.

Therefore, a number of actually measured curves shown by broken lines in FIG. 6 are prepared under different temperature conditions.

Although the temperature of the material monitored in this way is likely to change arbitrarily, the shear rate can be maintained at a constant value by setting the supply amount of the quantitative supply section 15 constant. It can be rewritten as a t-viscosity 7 curve. An example is shown in FIG.

As mentioned above, in a viscometer that has a general configuration of an existing screw-based plasticizing device, a metering supply section, and a capillary, when creating a Chi-7 curve, the area where the n is small is on the low temperature side, and the area where the n is large is on the low temperature side. By the way, it is shifted to the high temperature side. In order to correct this, the temperature value actually measured by the monitor thermometer is fed back to the master temperature controller, and the temperature value actually measured by using the temperature control thermometer 12.13 of the raw material supply means as a slave. When the value is lower than a predetermined value, the control set value of the slave thermometer is increased, and when the value is higher than the predetermined value, the control set value of the slave thermometer is controlled to be lowered. Cascade control can be used. According to such a method, the temperature is automatically kept constant at a predetermined value for the resin whose frictional heat generation is not so large and within a range where the shear rate is not so large. When automatically controlling the monitor temperature in this way, it is necessary to extract and organize only a specific temperature from among many temperature elements when creating a η curve. It can save a lot of time and effort.

Next, an embodiment of the online type viscometer B of the first invention will be described with reference to FIGS. 2, 3, and 4.

In the figure, the extruder 4 is provided with a feed mechanism 20 on the upper upstream side (right side in the figure), a hopper 21 on the upper upstream side of the feed mechanism 20, and a lower part of the hopper 21 with the feed mechanism 20. is communicated with. The feed mechanism 20 is configured as a single-axis screw conveyor and is driven by a motor 22. Although the details are not shown, the extruder 4 is of a known two-screw type, and the two screws are connected to a motor 23 and a speed reducer 24.
and a gear system W25. The extruder does not necessarily have to be a twin-screw type.

It may be an axle or multi-screw extruder with two or more axes. A branch channel 4b is provided in the resin channel 5 on the downstream side of the extruder 4. FIG. 4 shows a cross section taken along line XX in FIG. 3.

The branch flow path 4b is aligned with the inlet part], the quantitative supply block 5c], and the bolt 1
5d, it is connected to a flow path 15e leading to a gear pump 15a of a quantitative supply section of the online viscometer B.

Furthermore, a capillary part is fastened to the lower part of the quantitative supply part 15 with a bolt 3b. In this way, the measurement means 2 of the online viscometer B is controlled by the fixed quantity supply section 15 having a built-in flow path 15e, the capillary section 3, and the motor 16.
' is formed substantially the same as the measuring means 2 of the offline viscometer. Furthermore, the heater 3d, the pressure gauge 18 and the monitoring thermometer 19 are similarly connected to the control means 26. This online type viscometer B measures the viscosity while extruding the same thermoplastic synthetic resin as in the offline type viscometer A using the extruder 4. The extrusion amount and temperature of the extruder 4 during this extrusion work are the values measured at the viscosity liver B in the offline method, that is, t~η
The values of the curve are determined as a reference, and while checking the values measured with this online viscometer B, more appropriate operating conditions of the extruder 4 are adjusted to make the quality of the product uniform.

The operating conditions can be adjusted by adjusting the screw speed of the foot mechanism 20, the screw speed of the main screw (generally a two-shaft screw is often adopted, but a single screw can also be used), and the respective ratios. , when two or more feed mechanisms 20 are used, adjustment of the supply amount of each feed mechanism and their respective ratios, adjustment of the degree of kneading by the variable intermixing mechanism killed in the middle of the main screw 1, extrusion This includes adjusting the pressure value at the tip of the machine, and adjusting the temperature value when heating or cooling the extruder from the outside.

Next, an embodiment of the second invention will be described in detail. However, only the differences from the previous embodiments will be explained with reference to FIG.

A branch flow path 4b on the downstream side of the extruder 4 is connected to a switching valve 7. In this embodiment, first, the data passages 6a and 6C are communicated with each other by the switching valve rotor 7a (the state shown in FIG. 5). The η characteristic is determined, and then the switching valve 7 is switched to communicate the material passages 6b and 6C, and measurement is performed during the extrusion operation in the same manner as in the embodiment of the first invention. Adjust various operating conditions during extrusion work while referring to -η characteristics.

(Effects of the Invention) Since the present invention is configured as described above, it has the following unique effects.

(1) Total of offline method and online method? ! 111
Since the means are common, measured values from the offline method can be used as they are online, making it possible to accurately adjust various operating conditions during extrusion work.

(2) Especially in the second invention, by only switching the switching valve,
You can switch between online and offline methods.

(3) When operating the viscometer online, even if the temperature of the actual material measured by a1 deviates from the standard state,
The value of the deviation can be corrected using data measured off-line.

(4) In particular, if an infrared thermometer is used as the temperature monitor 1, the measured value can be expected to be accurate.

[Brief explanation of the drawing]

1 to 4 illustrate embodiments of the first invention, FIG. 1 is a partially cutaway side view showing an embodiment of an offline system, and FIG. 2 is a side view showing an embodiment of an extruder. FIGS. 3 and 4 are a vertical side view and a cross-sectional view showing an embodiment of the online system. FIG. 5 is a cross-sectional view illustrating the embodiment of the second invention;
The figure is a g-η curve diagram with temperature as a parameter, and FIG. 7 is a t-η curve diagram with shear velocity as a parameter. A...Offline type viscometer, B...Online type viscometer, 2, 2'...Measuring means, 4...Extruder, 4a...Tip part, 5...Flow path , 6a, 8b...
・Data flow path, 7...Switching valve, ]9...Monitor thermometer

Claims (5)

[Claims] (1) In the off-line type viscometer and the online type viscometer for melted plastic, the measuring means of both types of viscometer are substantially the same, and it can be installed in either of the two types. A viscometer characterized by the following. (2) A data flow path is branched into the flow path at the tip of the extruder that extrudes the molten plastic, and an online viscometer measuring means is connected to this data flow path, and a separate offline viscometer is connected. Both of these types of viscometers are
These measurement means are common, and a switching valve is interposed downstream of the sample flow path in the online type viscometer and the sample flow path in the offline type viscometer, and the measurement means is connected to the two sample flow paths. A viscometer characterized in that it can be connected to any one of the ducts. (3) Data regarding temperature and viscosity using the shear rate of the material as a parameter is collected in advance using an offline viscometer equipped with a material supply means with a built-in screw, and the data is collected as the viscosity value during online viscometer operation. 3. The viscometer according to claim 1, wherein the viscometer compensates for a difference between the measured temperature of the actual material and the standard temperature. (4) The capillary portion of the measuring means is provided with a monitoring thermometer at a position immediately in front of the capillary, as claimed in claim 1.
, 2 and 3 viscometers. (5) The viscometer according to claim 5, wherein the monitoring thermometer is an infrared thermometer.