JP3322185B2 - Method for eliminating aggregation in molecular weight measurement of PVC by SEC - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a SEC (Size)
Exfusion Chromatograph
The present invention relates to a method of effectively eliminating the aggregation of PVC (polyvinyl chloride) when measuring the molecular weight by y), and to the method of eliminating the aggregation when measuring the molecular weight of PVC by SEC.

[0002]

2. Description of the Related Art Measuring the molecular weight of a polymer is important to know its physical properties, and SEC is known as a means for rapidly measuring the molecular weight distribution as well as the average molecular weight of a polymer.

When measuring the molecular weight and the molecular weight distribution, the polymer needs to be dispersed to the molecular level in the solution based on the molecular size of the polymer in the solution.

On the other hand, PVC is a good solvent THF at room temperature.
When dissolved in (tetrahydrofuran), the presence of macromolecular aggregates may be found in the solution,
There is a problem that it affects the measurement of molecular weight and molecular weight distribution.

[0005] Therefore, as a method of eliminating aggregation in a PVC solution, conventionally, aggregation is eliminated by ultrasonically treating a PVC solution of THF for 15 minutes, and when a small amount of a nonionic substance is added to THF, degradation of PVC is simultaneously caused. Method (first conventional method) or PVC in THF
A method in which aggregation is dissociated by heating at 2 ° C. for 2 hours (second conventional method), and a PVC solution without aggregation is obtained by heating and dissolving in TCB (1,2,4-trichlorobenzene) at 120 ° C. for 12 hours. In addition, a method of measuring by high-temperature SEC at 110 ° C. (third conventional method) is known.

[0006]

However, according to the first conventional method, there is a possibility that the molecular chain is cut by the ultrasonic treatment and the original molecular weight and molecular weight distribution cannot be obtained.

Further, according to the second conventional method, THF
Is explosive, so heating is not preferred from the viewpoint of safety.

Further, according to the third conventional method, a long time of 12 hours is required for pretreatment of a sample, and a high temperature SEC is required.
There is a drawback that measurement can be performed only with such a special device.

Accordingly, an object of the present invention is to provide a pretreatment which can be performed without deteriorating the original characteristics of the sample, such as deterioration, and which can perform more accurate SEC measurement at room temperature using THF. An object of the present invention is to provide a method for eliminating agglomeration.

[0010]

A first technical means for solving the above-mentioned problem is to dissolve a PVC sample in THF as a mobile phase at room temperature and measure the molecular weight and molecular weight distribution by SEC. When measuring the molecular weight of PVC by SEC, PVC having an average degree of polymerization of 2350 ± 200 is constantly used under the heating conditions of a concentration of 0.1% or less and a heating temperature of 140 ± 2 ° C. for 6 hours or more using TCB as a solvent. Heat and dissolve while stirring, then reprecipitate the resin into the PV
C is used as a sample.

A second technical means for solving the above-mentioned problem is to dissolve a PVC sample in THF as a mobile phase at room temperature and measure the molecular weight and the molecular weight distribution by SEC. When measuring the molecular weight, PVC having an average degree of polymerization of 1300 ± 50, TCB as a solvent, a concentration of 0.1% or less, and a heating temperature of 130 ± 2.
The present invention is characterized in that the resin is heated and melted while constantly stirring under heating conditions of 6 ° C. or more for 6 hours, and then the reprecipitated resin is used as the PVC sample.

Further, a third solution for solving the above-mentioned problem.
The technical means of using PVC samples as a mobile phase in THF
Is dissolved at room temperature, and the molecular weight and the molecular weight distribution are measured by SEC. When measuring the molecular weight by SEC, PVC having an average degree of polymerization of 800 ± 50 is used at a concentration of 0.1% or less using TCB as a solvent, and Heating temperature 130 ± 2
The present invention is characterized in that the resin is heated and melted while constantly stirring under heating conditions of 6 ° C. or more for 6 hours, and then the reprecipitated resin is used as the PVC sample.

In each of the above technical means, the heating time under the heating condition may be 6 hours.

[0014]

Embodiments of the present invention will be described below.

As a sample, PVC (manufactured by Mitsubishi Chemical Corporation) having an average degree of polymerization P of 2350, 1300, or 800, obtained by a specific viscosity measurement method of a vinyl chloride resin test method of JIS-K6721 was used. Incidentally, these polymerization degrees P are generally well used, and the production error of the product is ± 200 when the average polymerization degree P is 2350, and the average polymerization degree P is 1
It can be understood that there are variations in the range of ± 50 at 300 and ± 50 at an average polymerization degree P of 800, and similar results can be obtained in this range of variation.

As a solvent, TCB (1, 2, 4-
Trichlorobenzene, 1st grade, manufactured by Wako Pure Chemical Industries, Ltd.) and THF (tetrahydrofuran, for high performance liquid chromatography, manufactured by Kishida Chemical Co., Ltd.) were used.

Further, in order to detect aggregation and measure the absolute molecular weight at the time of SEC measurement, the T
Shodex K on RIROTAR-V HPLC system
Two linear columns of F-806L are connected, and detector L
S (Light Scattering) (Wyatt
After a MiniDAWN3 angle detection manufactured by Technology, a refractometer RI (Refractive) is used.
An Index Detector (RID-300, manufactured by JASCO Corporation) was used. Data processing is data processing software ASTRA attached to the measuring device.
(Manufactured by Wyatt Technology). The column and RI were measured at room temperature of 25 ± 2 ° C.

Further, in order to determine the molecular weight in terms of PS (polystyrene), SEC (produced by Waters, 150
-CV) and a column (Waters, ULTRA S)
(TYRAGEL LINEAR) were connected, and the temperature in the apparatus system was set at 30 ° C. Data processing was performed using SEC data processing software 820J (manufactured by Nippon Waters Co., Ltd.) and then reprocessing with spreadsheet software for personal computers Excel (Microsoft Corporation). The standard PS is SM-1 manufactured by Showa Denko KK
05 (molecular weight, 3.055 × 10 ⁶ , 2.352 × 10
⁶ , 1.063 × 10 ⁶ , 4.56 × 10 ⁵ , 1.56
× 10 ⁵ , 6.64 × 10 ⁴ , 2.86 × 10 ⁴ , 9.
9 × 10 ³ , 3.2 × 10 ³ , 1.3 × 10 ³ ).

The following pretreatment was performed as a PVC sample.

That is, 50 ml of TCB as a solvent was placed in an Erlenmeyer flask (100 ml) equipped with a Dimroth reflux tube.
And 0.05 g of PVC as a sample (concentration 0.1
%), In an oil bath using a pipe heater with temperature control, and heated and melted while constantly stirring with a magnetic stirrer. The heating was performed at 120 ° C. for 12 hours, 130 ° C. for 6 hours and 12 hours, 140 ° C. for 6 hours and 12 hours, and 150 ° C. for 6 hours.

At this time, in order to prevent thermal deterioration of the sample,
0.1% w / v BHT (2,6-di-tert-butyl-4-methylphenol) was added.

The temperature in the oil bath is set at ± 2.
Controlled in ° C.

After cooling the dissolved PVC solution at room temperature for 30 minutes, 3 times the amount of methanol was added to precipitate the resin, the resin was reprecipitated, collected on a 0.65 μm filter, and washed with ethyl ether. The sample was dried at room temperature for 1 hour and further at 50 ° C. for 1 hour by a dryer to obtain a PVC sample.

Then, 0.01 g of the pre-treated PVC sample was weighed, THF as a mobile phase was added, the concentration was adjusted to 0.1%, and the mixture was left to dissolve for 2 hours. It was measured as 100 μl.

First, FIGS. 8 to 10 show the SEC measurement results of an untreated PVC sample which is a normal measurement method without performing the pretreatment.

FIG. 8 shows PV having an average degree of polymerization P of 800.
The SEC measurement result of the C sample is shown.
14.0ml storage capacitor V _R in the chromatogram of
Between 1 and 15.0 ml, that is, a peak smaller than the main peak appears at the bottom of the high molecular weight side. Also, LS
The chromatogram also shows the same, but it can be seen that the intensity is significantly larger than the intensity of the main peak. This reflects that the detection sensitivity of the polymer is high even at a low LS concentration.

Further, plots a curve showing the relationship between the storage capacitor V _R and molecular weight, it can be seen that the holding capacity V _R is changed suddenly slope of the curve in the boundary 15.6 ml. Retention capacity V
_{In the} region where _R is larger than 15.6 ml, a substantially linear relationship is obtained. In contrast, the holding capacitor V _R 14.
Between the 15.0 0 ml shows the same molecular weight regardless of the storage capacitor V _R, the molecular weight is almost constant at 1.0 × 10 ^6. This part corresponds to a part called so-called aggregation (aggregation peak).

Further, in the region where the holding capacity V _R is from 15.0 ml to 15.6 ml, the steep straight line is the region where aggregation and normally separated high molecular weight molecules are mixed. it is conceivable that.

9 and 10 show that the average degree of polymerization P is 130.
The SEC measurement results of the PVC samples 0 and 2350 are shown. In each figure, no clear aggregation peak appears in the RI chromatogram, but a bumpy peak appears in the polymer region in the LS chromatogram. Clearly appearing. Also in Plot showing the storage capacitor V _R and the molecular weight, the average degree of polymerization P holding capacitor V in 1300
_R is 15.2 ml, retention capacity V _R average degree of polymerization P is at 2350 is observed that the gradient 14.8ml smaller area is large.

[0030] Thus, in the chromatogram of the RI and LS, straight with no peaks of the polymer side-skirt, and plot a curve showing the relationship between the storage capacitor V _R and the molecular weight by the LS, the same gradient in the entire region Is a criterion for determining whether or not the cohesion has been eliminated.

Next, the SE of the pretreated PVC sample was
C measurement results are shown in FIGS. 1 to 7.

That is, FIGS. 1 and 2 show that the average degree of polymerization P is 2
FIG. 1 shows the SEC measurement results of a PVC sample having a heating temperature of 130 ° C. for 6 hours and a heating temperature of 140 ° C. for 6 hours.

In the RI chromatogram, no aggregation peak is clearly observed in any of the figures, as in FIG. On the other hand, in the LS chromatogram, it can be seen that the aggregation peak is significantly eliminated and hardly recognized as compared with the case of FIG. That is, a slight aggregation peak is still recognized in FIG. 1, whereas it is almost completely eliminated in FIG.

Further, in a plot curve showing the relationship between the storage capacitor V _R and the molecular weight, the retention capacitor V _R in FIG. 1 is 14.
In 7 ml, 2 in the holding capacitor V _R is has inflection point 14.6 ml, is moving compared to the high molecular weight side in FIG. 10. Then, the slope of the curve on the high molecular weight side is smaller than that in FIG. 10, and in particular, in FIG. 2, it is recognized that the slope of the curve in the main region is substantially equal.

From the above, by performing the pretreatment under the heating condition of 140 ° C. for 6 hours, the coagulation can be almost completely eliminated. It can be seen that aggregation remains. That is, this point can be easily compared with FIG. 3 in which the chromatograms of the LS in FIGS. 1 and 2 are overwritten.

[0036]

[Table 1]

Table 1 shows that the average polymerization degree P is 2350.
The actual SEC / LS of the absolute molecular weight and the untreated absolute molecular weight according to the heating conditions of the pretreatment in the VC sample
3 shows the measured values (average value of three times) measured by the / RI system. As shown in Table 1, the absolute molecular weight determined by LS is shown in Table 1.
Comparing the molecular weights of C with each other, at a heating temperature of 130 ° C., 6
Under the heating condition of time, the number-average molecular weight Mn, the weight-average molecular weight Mw, and the Z-average molecular weight Mz are reduced by about 13%, 21%, and 42%, respectively, as compared with the case where the pretreatment is not performed. Further, the molecular weight decreases as the pretreatment time and the pretreatment temperature rise.

FIGS. 4 and 5 show that the average degree of polymerization P was 235.
0 shows a molecular weight distribution curve of a sample pretreated under heating conditions of 130 ° C. for 6 hours and a heating temperature of 140 ° C. for 6 hours for a PVC sample of 0, and a molecular weight distribution curve of 1.0 × 10 ^6. Although the ratio of the above-mentioned aggregation region is greatly reduced, and the ratio of the low-molecular region having a molecular weight of 3.0 × 10 ⁴ or less is increased, the size of the main region of the chromatogram does not change at all. Therefore, it can be estimated that the molecular weight does not decrease due to the thermal decomposition due to the pretreatment of the PVC sample. As for the rate of decrease in molecular weight due to the pretreatment, the Z average molecular weight Mz is the largest, and the weight average molecular weight Mw and the number average molecular weight Mn decrease in this order. From these facts, it can be understood that the reason why the average molecular weight of the pretreated PVC sample is smaller than that of the untreated PVC sample is due to the elimination of aggregation.

The heating condition at a heating temperature of 140 ° C. for 12 hours is more preferable in terms of eliminating aggregation, but in terms of shortening the pretreatment time, the heating condition at a heating temperature of 140 ° C. for 6 hours is preferable.

Under the heating conditions of a heating temperature of 150 ° C. for 6 hours, the molecular weight shows a higher value as compared with the other processing temperatures, and it is considered that a part of the sample was crosslinked, but the sample is colored. From this fact and the shift of the RI chromatogram to the lower molecular direction, it is considered that thermal degradation has occurred.

From the above, the average degree of polymerization P was 2350
In the case of the above PVC sample, it is possible to efficiently dissolve agglomeration without heat degradation of the sample by heating and dissolving the sample while constantly stirring with a stirrer under the heating condition of 140 ° C. for 6 hours. Understand what you can do.

FIGS. 6 and 7 show that the average degree of polymerization P is 1300.
9 shows SEC measurement results of PVC samples which were pretreated under heating conditions of 130 ° C. for 6 hours for 800 and 800 PVC samples, respectively.

[0043]

[Table 2]

[0044]

[Table 3]

Tables 2 and 3 show the absolute molecular weight and the untreated absolute molecular weight measured at that time measured by the SEC / LS / RI system (average of three measurements).

[0046] In this case, Both, RI, not observed at all horizontal clustering regions in a plot curve representing the relationship between the aggregate peak and the storage capacitor V _R and the molecular weight of the chromatogram of LS.

In particular, for the PVC sample having an average degree of polymerization P of 800, it can be understood from the above that the aggregation peak completely disappeared. The average degree of polymerization P is 13
For 00 of the PVC samples from plots curves showing the relationship between the storage capacitor V _R and molecular weight, short linear region of the steep compared to the case shown in FIG. 9, and has a gentle slope, substantially constant Is improved so that it can be approximated by a straight line having a gradient of

The heating was carried out at 130 ° C. for 12 hours for 12 hours.

From the above, the average degree of polymerization P was 1300
And 800 PVC samples, heating temperature 130
It can be understood that heating and dissolving while constantly stirring with a stirrer under heating conditions of 6 ° C. for 6 hours can provide a PVC sample that can efficiently eliminate aggregation without thermal degradation of the sample.

In the pretreatment of the PVC sample having each average polymerization degree P, when the heating temperature was 120 ° C. for 12 hours, the aggregation was not completely eliminated and was insufficient. Also,
At the time of heating and dissolving, when stirring is performed intermittently, a large percentage of aggregation remains, and it is preferable to continuously stir constantly.

Further, in the pretreatment step, when the concentration of the PVC sample when it is dissolved in TCB is doubled, the aggregation is not completely eliminated, and the PVC sample is dissolved in a dilute solution having a concentration of 0.1% or less. It is necessary.

Further, since LS is used for the detector, the absolute molecular weight can be obtained, and a more accurate molecular weight can be obtained by eliminating aggregation.

[0053]

As described above, the SEC of the PVC of the present invention is as described above.
According to the method for eliminating aggregation when measuring the molecular weight by
The advantage that the SEC measurement at room temperature using THF by predetermined pretreatment of the VC sample eliminates aggregation without deteriorating the sample's original characteristics such as deterioration, and enables more accurate SEC measurement of molecular weight and molecular weight distribution. There is.

Further, by setting the heating time to 6 hours, there is an advantage that the efficiency can be improved within a range that does not hinder the measurement.

[Brief description of the drawings]

FIG. 1 is a diagram showing chromatograms of RI and LS, and the relationship between molecular weight and retention capacity.

FIG. 2 is a diagram showing chromatograms of RI and LS, and the relationship between molecular weight and retention capacity.

FIG. 3 is a diagram in which the chromatograms of the LS in FIGS. 1 and 2 are overwritten.

FIG. 4 is a diagram showing a molecular weight distribution curve.

FIG. 5 is a diagram showing a molecular weight distribution curve.

FIG. 6 is a diagram showing chromatograms of RI and LS, and the relationship between molecular weight and retention capacity.

FIG. 7 is a diagram showing chromatograms of RI and LS, and the relationship between molecular weight and retention capacity.

FIG. 8 is a diagram showing a chromatogram of RI and LS in an untreated PVC sample, and a relationship between molecular weight and retention capacity.

FIG. 9 is a diagram showing a chromatogram of RI and LS in an untreated PVC sample, and a relationship between molecular weight and retention capacity.

FIG. 10 is a diagram showing a chromatogram of RI and LS in an untreated PVC sample, and a relationship between molecular weight and retention capacity.

────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Hiroaki Minami 1-114, Nishisuehiro-cho, Yokkaichi-shi, Mie Sumitomo Wiring Systems, Ltd. (72) Inventor Sadao Mori 4-8, Ibuka-cho, Nakamura-ku, Nagoya-shi 56) References JP-A-1-98963 (JP, A) JP-A-8-271494 (JP, A) JP-A-2-8740 (JP, A) JP-A-4-84761 (JP, A) JP-A-4-84760 (JP, A) JP-A-3-210475 (JP, A) JP-A-4-172248 (JP, A) JP-A-8-73646 (JP, A) JP-A-9-210929 (JP , A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G01N 30/06 G01N 30/88

Claims (4)

(57) [Claims] 1. A PVC sample is dissolved in THF as a mobile phase at room temperature, and the molecular weight and the molecular weight distribution are measured by SEC. When measuring the molecular weight by SEC of PVC, PVC having an average degree of polymerization of 2350 ± 200 is used as a solvent. T
Using CB, a concentration of 0.1% or less and a heating temperature of 14%
Under the heating condition of 0 ± 2 ° C. for 6 hours or more, the resin is heated and dissolved while being constantly stirred, and then the reprecipitated resin is used as the PVC sample. Solution method. 2. A PVC sample is dissolved in THF as a mobile phase at room temperature, and the molecular weight and the molecular weight distribution are measured by SEC. When measuring the molecular weight by SEC of PVC, PVC having an average polymerization degree of 1300 ± 50 is used as a solvent. TC
B, the concentration is 0.1% or less, and the heating temperature is 130%.
Dissolving agglomeration during molecular weight measurement by SEC of PVC, characterized in that the resin is heated and melted while constantly stirring under heating conditions of ± 2 ° C for 6 hours or more, and then the reprecipitated resin is used as the PVC sample. Law. 3. A PVC sample is dissolved in THF as a mobile phase at room temperature, and the molecular weight and the molecular weight distribution are measured by SEC. When measuring the molecular weight by SEC of PVC, PVC having an average polymerization degree of 800 ± 50 is used as a solvent. TCB
With a concentration of 0.1% or less and a heating temperature of 130 ±
A method for eliminating aggregation when measuring the molecular weight of PVC by SEC, wherein the resin is heated and melted while being constantly stirred at 2 ° C. for 6 hours or more, and then the reprecipitated resin is used as the PVC sample. . 4. The P according to claim 1, wherein the heating time under said heating condition is 6 hours.
A method for eliminating aggregation when measuring the molecular weight by VC SEC.