JP5086041B2 - Simple melt viscosity measurement method for thermoplastic resins - Google Patents

Description

  The present invention relates to a simple melt viscosity measurement method capable of measuring even a small amount of sample.

Thermoplastic resins are used in a wide range of fields because they are lightweight and have excellent processability. Further, as the processing accuracy increases, the molded product becomes smaller and more precise. Therefore, since variations in the quality of the thermoplastic resin used have a significant effect on the quality of the product, standards regarding the quality of the material resin are set for strength, melting point, and many other items. , There is MFR. On the other hand, since MFR has a correlation with the molecular weight of the resin, it is often used as an index for judging the deterioration state of a product actually used.
Standard methods for measuring MFR include JIS K 7210 and ISO 1133, but this method requires a specific device and requires 3 to 8 g of a sample. Therefore, it is necessary to collect some molded products even if they are small molded products that are worried about variations among products. Further, even if a product is partially concerned about deterioration, it is necessary to measure with a sample including a portion that has not deteriorated other than the intended portion for which deterioration is to be determined.

  Under such circumstances, there is a demand for a method capable of measuring MFR in as small a quantity as possible with only a small molded product or a specific part of the molded product, but no such method has been proposed.

  The present invention is to provide a method for easily measuring the melt viscosity from a small amount of thermoplastic resin, and more specifically, to provide a method for accurately measuring the MFR value from a small amount of sample. It is.

  As a result of intensive studies on the above-mentioned problems, the present inventor previously obtained the relationship between the characteristics when the thermoplastic resin is melted under a predetermined condition and the MFR as a relational expression, and measures the characteristics at the time of melting. The present inventors have found that the MFR can be obtained by putting the obtained value into a relational expression, and the present invention has been completed.

  That is, the first of the present invention is a simple melt viscosity measuring method in which the size of the extrudate obtained by melting a thermoplastic resin and applying a load under a predetermined condition is used as an index of the melt viscosity of the thermoplastic resin. is there.

  In the second aspect of the present invention, the melt viscosity is MFR, the correlation between the MFR of the thermoplastic resin and the size of the extrudate is obtained in advance, and the pressure measured with the thermoplastic resin at the measurement target location based on the correlation. The simple melt viscosity measuring method according to the above, wherein the MFR of the measurement target location is obtained by applying the size of the exhibit.

  The third of the present invention is that the predetermined condition is that a predetermined load is applied for a predetermined time in a state where a predetermined amount of a thermoplastic resin is sandwiched between glass plates at a predetermined temperature, and the size of the obtained extrudate is glass. The method for measuring a simple melt viscosity according to the above, characterized in that the area is the area of a thermoplastic resin that is squeezed between plates.

  A fourth aspect of the present invention is the simple melt viscosity measuring method according to the above, wherein a predetermined amount of the thermoplastic resin is preliminarily formed into a circular shape, and the area of the expanded thermoplastic resin is replaced with a diameter. It is.

  According to a fifth aspect of the present invention, there is provided the simple melt viscosity measuring method according to the above, wherein the predetermined amount of the thermoplastic resin is 50 mg or less and the size of the extrudate is not less than a measurable amount.

  A sixth aspect of the present invention is the simple melt viscosity measurement method described above, wherein the thermoplastic resin is a polyacetal resin.

  7th of this invention is a quality control method characterized by using the melt viscosity of the thermoplastic resin obtained by the said measuring method for quality control of a thermoplastic resin molded product.

  According to the present invention, the MFR value of a thermoplastic resin can be accurately measured with a small amount of sample using a general-purpose physics and chemistry apparatus without using an expensive apparatus. It becomes possible to manage the MFR change of the molded product.

  By measuring the size of the extrudate obtained by melting a thermoplastic resin whose melt viscosity has been measured in advance and applying a load under predetermined conditions, the correlation between the melt viscosity and the size of the extrudate is obtained. Find in advance. The melt viscosity can be obtained by measuring the size of the extrudate under a predetermined condition with a sample for which the melt viscosity is to be obtained, and applying this correlation.

  For example, the relationship between the size of the expanded product obtained by melting a thermoplastic resin and applying a load under a predetermined condition and the MFR is obtained in advance as a relational expression. Can be requested. That is, the viscosity is obtained by putting the value of the size of the extrudate obtained under predetermined conditions into the relational expression.

  First, in the resin to be measured in advance, the correlation between the MFR and the size of the extrudate is obtained.

Prepare several different samples for which MFR was measured and measure a predetermined amount. At this time, the amount to be measured is determined according to the size of the hot plate of the heating temperature control device so that the expanded product is obtained in a uniformly spread form. In addition, it is desirable that the sample is preliminarily shaped so as to be circular and have the same thickness so that the extrudate can easily spread uniformly. When the pressure is spread, a uniform spread can be obtained by applying a uniform load with the sample sandwiched between flat plates. At that time, it is convenient to use a glass plate as a flat plate because the size of the extrudate can be easily observed. As a method of applying a predetermined load, it is convenient to use a weight. In addition, two glass plates are placed on a hot plate controlled at a predetermined temperature, and a weight is further placed thereon to preheat to a predetermined temperature.
After the above preparation is complete, place the sample in the center of one glass plate, and place another glass plate on top of it. In this state, heat the sample to the specified temperature, and then place it on the stacked glass plate. A weight for preheating at the same temperature is put on the plate and a load is applied for a certain period of time, and then the sample is cooled to room temperature. The area of the obtained extrudate can be easily calculated from the diameter because a circular extrudate is obtained in the case of a sample that has been formed into a circular shape in advance.

  The correlation between this area and the MFR value is obtained from the areas of the extrudates of samples having different MFRs obtained in this way.

  If the area of the extrudate is measured by the same operation in the sample for which MFR is to be measured, the MFR can be obtained by applying the area obtained to the correlation obtained in advance.

  The thermoplastic resin according to the present invention is not particularly limited, and may be a single material or a mixture that is uniformly mixed. Examples thereof include polyolefins such as polyethylene and polypropylene, polystyrene, methacrylic resin, polyacetal (polyoxymethylene), polyamide, polyesters such as polycarbonate and polybutylene terephthalate, polyesteramides, polyphenylene sulfide, and ABS.

  Further, the thermoplastic resin may contain a small amount of a filler, an additive for improving stability, and the like.

  The heating temperature control apparatus used in the present invention only needs to have a temperature control accuracy within 1 ° C., and it is easy to use a melting point measuring device. Although it is convenient to use a glass plate, any glass plate may be used, and a slide glass and a cover glass are easily available.

Example 1
Measurement was performed using polyoxymethylene (hereinafter referred to as POM) measured by a conventional MFR measurement method (JIS K 7210).

  First, 20 mg of POM pellets having a POM MFR value of 2.4 were measured with a precision balance, placed in a 5φ × 2 mm aluminum pan, melted on a 190 ° C. hot plate, and quickly shaped into a tablet.

  Next, two 50 g weighting weights and approximately 25 mm square glass plates (cut glass slides) are placed on a hot plate controlled at 190 ° C. and kept at 190 ° C. When the temperature reached a constant temperature, the tablet was sandwiched between the glass plates and the resin was dissolved by heating for 5 minutes. Next, a weighting weight having a constant temperature of 190 ° C. is placed on the glass plate for 30 seconds, and then the weight is removed quickly and placed on an iron plate at room temperature and allowed to cool to room temperature.

The diameter of the circular film obtained from the above operation was measured in two or more directions using a caliper, and a film area of 53 mm ² was obtained using the average diameter.

  Further, those having different MFRs were measured in the same manner, and the values shown in Table 1 were obtained. Based on this result, a relational expression between the area and the MFR value was obtained to obtain y = 1.7224ln (x) −6.4549.

  Next, for the MFR unknown sample, the MFR was obtained by substituting the area obtained by the same measurement as described above into the equation. Moreover, it measured by the JIS K 7210 method, the value was verified, and as shown in Table 2, it was confirmed that the measurement results almost coincided.

Example 2
In polybutylene terephthalate (hereinafter referred to as PBT), it was confirmed that the relational expression was obtained in the same manner as in Example 1.

  That is, when the simple MFR was measured at 245 ° C. in the same manner as in Example 1, the results shown in Table 3 were obtained, and the relationship shown in FIG. 2 was established.

The relationship between the MFR measurement value of Table 1 and the simple measurement value of melt viscosity is represented in a graph. The relationship between the MFR measurement value of Table 3 and the simple measurement value of melt viscosity is represented in a graph.

Claims (5)

It is a simple melt viscosity measurement method in which the size of a spread product obtained by melting a thermoplastic resin and applying a load under predetermined conditions is used as an index of the melt viscosity of the thermoplastic resin ,
The amount of the thermoplastic resin used is 50 mg or less, and the size of the extrudate is not less than the measurable amount,
The melt viscosity is melt mass flow rate (hereinafter referred to as MFR), and the correlation between the MFR of the thermoplastic resin and the size of the extrudate is obtained in advance, and the measurement is performed with the thermoplastic resin at the measurement target location based on the correlation. A simple melt viscosity measuring method characterized in that the MFR of a measurement target location is obtained by applying the size of the extrudate . The predetermined condition is to apply a predetermined load for a predetermined time in a state where a predetermined amount of thermoplastic resin is sandwiched between glass plates at a predetermined temperature, and the size of the obtained expanded product is expanded between the glass plates. The simple melt viscosity measuring method according to claim 1 , wherein the area is a thermoplastic resin area. 3. The simple melt viscosity measuring method according to claim 2 , wherein a predetermined amount of the thermoplastic resin is preliminarily formed into a circular shape, and the area of the expanded thermoplastic resin is substituted for the diameter. The simple melt viscosity measuring method according to any one of claims 1 to 3 , wherein the thermoplastic resin is a polyacetal resin. A quality control method characterized by using the melt viscosity of the thermoplastic resin obtained by the measurement method according to any one of claims 1 to 4 for quality control of a thermoplastic resin molded product.

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