JPH032645A - Capillary rheometer - Google Patents

Abstract

PURPOSE:To improve the measuring accuracy for softening temperature and incipient fluidization temperature by obtaining the temperature based on the intersection between a straight line which is approximate to the curve section at the minimum gradient and a straight line which is approximate to a curve section including a point where the amount of piston movement leaves by a specified value. CONSTITUTION:A control circuit 14 stores a pair of data of fluidization curves based on the amount of piston movement that is detected with a potentiometer 11 and the test temperature detected with a temperature detector 12. Then, the intersection between a straight line which is approximate to the curve section including a point where the minimum gradient is formed viewed from the higher temperature side and a straight line which is approximate to the curve section including a point where the amount of the piston movement leaves by a specified value DELTAS is obtained. Then, the test temperature corresponding to the intersection is determined as the outflow starting temperature. The curve section where the minimum gradient is formed viewed from the lower temperature side is detected, and the softening temperature is determined by the same way. Thus, the measuring accuracy when the softening temperature and the outflow starting temperature of a sample are automatically determined can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a capillary rheometer, and particularly to a technique for automatically determining the softening temperature and outflow start temperature of a sample with high accuracy.

B. Prior Art This type of rheometer measures the viscosity of resins, foods, ceramics, raw rubber, etc. under desired temperature conditions. It consists of a control device (not shown) that calculates viscosity such as viscosity and flow value. The main body portion 20 includes a cylinder 2 into which a sample to be measured 1 is placed, a heater 3 provided on the outer periphery of the cylinder 2, and a die 4 having a hole 4a for passing the sample provided on the lower surface of the cylinder 2. , a die presser 5 that is screwed onto the cylinder 2 and attaches the die 4 to the cylinder 2;
It has a piston 6.

Figure 6 shows the flow of the piston 6 during the outflow process of the sample 1.
It is a flow curve showing the relationship between loque (travel amount) and test temperature. The sample 1 is placed in the cylinder 2, and a constant load is applied from above it via the piston 6 as shown by arrow a in FIG.
When the degree of heating of the sample 1 by the heater 3 is increased northward at a constant time ratio, the granular sample 1 gradually becomes softer between A-8 and the granular voids are crushed, so the progress of the softening is The stroke of the piston 6 increases accordingly. At point B, the sample 1 is almost completely softened, and when it reaches point 6, it is completely softened and becomes molten, but the stroke of the piston 6 is maintained at an almost constant value between B and C. However, when the 6th point is reached, the completely softened and molten sample 1 begins to flow out from the hole 4a, and at the 0 point, it completely flows out and the test ends.

In such a flow curve, the temperature corresponding to point B is the softening temperature Ts, and the temperature corresponding to point C is the outflow start temperature Tfb.
These temperatures Ts and Tfb are measured and sample 1
Evaluate the viscosity of

Conventionally, in determining the softening temperature Ts and outflow start temperature Tfb, for example, tangent lines are drawn near point B and near point 0 of the flow curve recorded on an XY plotter.

K2 and 3. Draw 4 to each, and draw 2 to □ and 2 to the tangent line.
The temperature at the intersection P12 is the softening temperature Ts, and the temperature at the intersection point P12 is
The temperature at the intersection point P with this point was defined as the outflow start temperature Tfb.

For this reason, there is a problem that it takes time to detect the softening temperature Ts and the outflow start temperature Tfb, and errors due to individual differences are unavoidable.

Therefore, using an arithmetic device such as a computer, the above-mentioned tangent lines □, 2 and 3. An attempt has been made to find 4 by calculation, and automatically find the softening temperature Ts and outflow start temperature Tfb from the intersections Pi□ and P34 of these tangents.

Problems to be Solved by the C0 Invention However, the softening temperature Ts and the outflow start temperature Tfb
T! :The problem is how to find the tangent line when finding it by calculation. That is, for example, in the flow curve shown in FIG. 7, when determining Tfb, the line tangent to the maximum positive slope portion of the flow curve is defined as the tangent K3. If the line tangent to the minimum positive or negative slope is calculated as 4, then tangent 1; J(,.

The intersection point P34 of K, deviates greatly from the true Tfb, resulting in a large detection error. As a result, there is a problem in that the measured viscosity is incorrectly detected.

A technical object of the present invention is to improve the accuracy of determining tl when automatically determining the softening temperature and outflow start temperature of a sample.

06 Means for Solving the Problems The capillary rheometer of the present invention has a piston movement! ! A movement sub-chamber means for measuring the II amount, a test temperature measuring means for measuring the test temperature, and a memory for storing data of a flow curve pairing the piston movement amount and the test temperature based on the measurement results of both measuring means. and calculation means for detecting the outflow start temperature and the softening temperature based on the flow curve data stored in the storage means. This calculation means calculates a linear equation in the section where the flow ΔJ curve shows the minimum slope, and then calculates the calculated piston displacement amount a for a predetermined test temperature on this linear equation and the actual piston displacement for the predetermined temperature stored in the storage means. Find a point where the difference from the amount of movement is greater than a predetermined value, find a straight line equation that represents the curve section on the flow curve that includes that point,
Find the test temperature at the intersection of the straight lines indicated by the two straight line equations obtained. The outflow start temperature is a test temperature determined by the calculating means based on a linear equation of the curve section that first has the minimum slope while viewing the flow curve from the higher test temperature. The softening temperature is a test temperature determined based on a linear equation of the curve section that first has the minimum slope when viewing the flow curve from the lowest test temperature.

20 Effects To explain using FIG. 4, the outflow start temperature Tfb is determined by the curved section 1f (which exists in or near f t n) where the flow curve has the minimum gradient first when looking at the flow curve from the higher test temperature. , the amount of piston movement increases rapidly from this section t toward the higher temperature side.In addition, the softening temperature Ts
The curve exists within or near the curve section ti where the gradient is first minimum when viewed from the lower test temperature, and the amount of piston movement rapidly decreases from this section ti toward the lower test temperature.

The curve section □ is expressed as yn"anxn+bn -' (1) However, a
o; slope bn; can be approximately expressed by the intercept at 2 of the y-axis of direct myn.

Similarly, the curve section ti represents the amount of piston movement in the section as y
□, let the test temperature be X, then yi=aixi+bi
-(2) However, it can be approximately expressed by the intercept on the y-axis of ai; slope bi; direct myi.

Therefore, when determining the outflow start temperature Tfb.

The variable XQ of the linear equation shown by the first equation is changed toward the higher test temperature, and the piston movement on the straight line shown by the linear equation at this time lit'In□+ynz+
..., and the difference between this calculated value and the actual piston movement amount Vn1'U'/nz'"°" ynz-yn
%J l [ynz-ynz"J" is the predetermined value ΔS0
The point y on the flow curve is as follows. Detect k'.

Next, find the interval that includes this point. A linear equation approximating ′ is obtained using the following equation (3).

yl'=al'xl'+bn'-(3) This is
It can be easily determined using a plurality of actually measured piston movement amounts and test temperatures before and after the point 3'nk'' at which the value of the difference is greater than or equal to ΔSn.

Next, the intersection point K of the two straight lines shown in the first equation and the third equation, respectively. Find the temperature of this intersection K.

is determined as the outflow start temperature Tfb.

In this way, the straight line Yn with the minimum gradient and the predetermined value y of the piston movement amount on this straight line. The value y of the actual piston movement distance away from k by ΔSn. Straight line y n+ in a predetermined section including k′
By determining the test temperature at the intersection point Kn as the outflow start temperature Tfb, ΔSn can be predetermined so as not to be affected by noise, or by setting ΔSΩ that is optimal for the flow curve specific to the sample to be determined. , it is possible to obtain an outflow start temperature Tfb that is extremely close to the true outflow start temperature.

This also applies to the softening temperature Ts.

That is, when determining the softening temperature Ts, the variable X in the linear equation shown by the second equation is changed to the lower test temperature, and the piston movement J
l yL* ylz+... is calculated.

This calculated value and the actual piston movement amount yi□′yiz
”...difference ryL yit'J * ryi2
YiSJ... decreases to a predetermined value of 4 toward the lower test temperature.
Find the point yilc' which is 80 or more. Next, this point y
A linear equation that approximates the section tt+ on the flow curve including lk' is obtained by the following equation (4).

yi'=ai'xi'jubi' +++ (4) Then, the intersection point Ki of the straight lines shown by the second equation and the fourth equation is determined, and 1 is selected as the softening temperature Ts at this intersection point.

F. Embodiment FIG. 1 is a block diagram of a control device for a capillary rheometer according to the present invention, which is used together with the tester main body 20 shown in FIG. 5.

In the figure, the potentiometer 11 generates a screw movement amount signal corresponding to the amount of descent of the piston 6, and the temperature sensor 12 generates a temperature signal corresponding to the test temperature of the sample 1 heated by the heater 3. Control circuit 1 via 13
Enter 4. The control circuit 14 is a C.
It includes a PU 14a, a memory L4b for storing the amount of piston movement detected by the potentiometer 11 and the test temperature detected by the temperature detector 12 as data of a pair of flow curves. The keyboard 15 is used to input values such as the aforementioned ΔS n + ΔS□. The heater 3 is controlled by a control circuit 14 so that the test temperature of the sample 1 is increased at a constant time rate. The printer 16 records test conditions, test results, and the like.

FIG. 2 is a flowchart showing the procedure for determining the outflow start temperature Tfb, and FIG. 3 is a flowchart showing the procedure for determining the softening temperature Ts.

First, the procedure for determining the outflow start temperature Tfb will be explained with reference to the explanatory diagram of FIG. 4.

In the first step S1, flow curve data stored in the memory 14b from the start of the test to the end of the test is read.

In the next step S2, since unstable elements and noise components are included in the part immediately after the start of the test and the part immediately before the end of the test, in order to remove these, the lower limit of the piston movement is set to 10%.
Delete the data below and above 90% of the upper limit.

In step S3, in order to detect the curve section with the minimum slope, the effective curve section from which noise components have been removed is divided into, for example, 30 sections in the time axis direction (the direction in which the test temperature increases), and the curve slope of each section is Detect.

Next, in step S4, the curve section that first has the minimum slope when viewed from the higher test temperature is detected.

That is, the curve section n in FIG. 4 is detected.

Subsequently, in step S5, this minimum slope curve section jQ
The flow curve within is linearly approximated by the first equation. Next, in step S6, the test temperature Xna near the middle of 0 is determined by the straight line curve section represented by ryn=anXn+bnJ, and the value XrlL (=xno
+c), and in step s8, this
Piston movement amount y when substituted into the mouth. Calculate 1. Then, in step S9, the calculated piston movement amount yn
The absolute value of the difference 'Yni - 'in' between t and the actually measured piston movement i y nx at the test temperature indicated by Determine whether If,”/nx
-'/mouth, ≧ΔSnJ, the process returns to step S7, updates the variable Xfi to Xnz (=Xns 1C), and then steps S8, 89. Execute the SIO process again.

As a result, if step S10 is affirmed when xl = is determined by the third equation described above.

Next, in steps S12 and S13, the curve section with the minimum slope is determined. Find the intersection point Kn between the straight line MyΩ, which is a linear approximation of ΔS, and the straight line yn', which is a linear approximation of the curve section 1o/ that includes the point where the piston movement distance is ΔS, and the test temperature corresponding to this intersection Kn is set as the outflow start temperature Tfb. Decide and end the process.

On the other hand, in the procedure for determining the softening temperature Ts shown in FIG. 3, the same process is executed to determine the softening temperature Ts. However, when determining the softening temperature Ts,
The difference is that the curve section ti having the minimum slope is detected from the lower test temperature (step 84'). Also,
In order to detect the curve section ti'', which is separated by ΔSi from the piston movement fityni on the linear equation of the minimum slope, in the direction in which the test temperature decreases, the variable Xi is set as rxi-C''.
The difference is that they are sequentially updated as (step S7')
), other processing is a subscript sign. changes to i and becomes Tf again.
This is the same as the case where Tfb is determined only by changing b to Ts. Therefore, in FIG. 3, steps similar to those in FIG. 2 are denoted by the symbol "'", and their explanation will be omitted.

In this way, a straight line indicating the curve section with the minimum slope is found, and a point on the flow curve where the piston travel amount is increased by a predetermined value ΔS from the piston travel amount for a given temperature on this straight line is found, and the section that includes this point is found. By determining the intersection of the straight line and the above-mentioned straight line as the outflow start temperature Tfb or the softening temperature Ts, ΔS can be set to a small value that does not erroneously detect noise components of the piston movement amount.

It becomes possible to automatically determine a temperature that is extremely close to the true outflow start temperature or softening temperature, and the measurement accuracy of the device can be greatly improved. Furthermore, since ΔS can be set using the keyboard to an optimal value according to the flow curve specific to the sample, a highly versatile capillary rheometer can be provided.

Although the flow curve is divided into 30 parts in the time axis direction to detect the curve section having the maximum /Jl slope, the number of parts may be divided into more than 30 parts or less than 30 parts depending on the required measurement speed and measurement accuracy. .

G9 Effects of the Invention Since the present invention is configured as described above, the measurement accuracy when automatically determining the outflow start temperature and the softening temperature from the flow curve drawn by the data pairing the test temperature and the piston movement amount can be greatly improved. can be improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the capillary rheometer control device according to the present invention, FIG. 2 is a flowchart showing the procedure for determining the outflow start temperature, and FIG. 3 is a flowchart showing the procedure for determining the softening temperature. Char 1., Figure 4 is an explanatory diagram of the method for determining the outflow start temperature and softening temperature, Figure 5 is a cross-sectional view of the test machine main body, Figure 6 is an explanatory diagram showing an example of the flow curve, and Figure 7 is an explanatory diagram of the method for determining the outflow start temperature and softening temperature. It is an explanatory view showing a problem when automatically determining a starting temperature. ■=Sample 2 Niji cylinder 3: Heater 9: Die 12: Temperature detector 14: Control circuit 14b: Memory 20: Testing machine body 6: Piston 11: Potentiometer 13: Input/output circuit 14a: CPU 15: Keyboard Patent applicant Co., Ltd. Shimadzu Corporation Patent Attorney Fuyuki Nagai Fig. 1 Fig. 2/ Fig. 3 Fig. 5 Fig. s fb Test temperature - to L $ Kutsuyasu Fig. 7

Claims (1)

[Claims] A sample placed in a cylinder is heated at a fixed time rate while being pressed by a piston, and the molten sample flows out from a thin tube hole at the bottom of the cylinder. A capillary rheometer that measures the viscosity of a sample based on a curve, comprising a movement measuring means for measuring the amount of piston movement, a test temperature measuring means for measuring the test temperature, and a piston movement based on the measurement results of both measuring means. storage means for storing flow curve data as a pair of quantity and test temperature; and after determining a linear equation of the section where the flow curve exhibits the minimum slope based on the data, Find a point where the difference between the calculated value of the piston movement amount and the actual piston movement amount for the predetermined temperature stored in the storage means is greater than or equal to a predetermined value, and calculate a linear equation representing a curve section on the flow curve that includes that point. and calculation means for calculating the test temperature at the intersection of the straight lines respectively indicated by the two calculated linear equations, and the calculation means calculates the curve section that first has the minimum slope when viewing the flow curve from the side with the higher test temperature. The test temperature determined based on the linear equation of is the outflow start temperature, and the softening temperature is the test temperature determined based on the linear equation of the curve section that first has the minimum slope when looking at the flow curve from the lowest test temperature. A capillary rheometer characterized by: