JP7141608B2 - A method for measuring the glass transition temperature of thermosetting resins using high-speed calorimetry - Google Patents

Description

Application of Article 30, Paragraph 2 of the Patent Act Exhibition date: November 2, 2018 Exhibition name: The 54th Thermal Analysis and Thermal Analysis Symposium held by the Japan Society of Calorimetry Venue Tokyo Institute of Technology Suzukakedai Campus (4259 Nagatsuta-cho, Midori-ku, Yokohama City, Kanagawa Prefecture)

The present invention relates to a method for measuring the glass transition temperature of a thermosetting resin using fast calorimetry (hereinafter sometimes referred to as FSC).

High-speed calorimetry is a type of differential scanning calorimeter method (hereinafter sometimes referred to as DSC). This is a technique that can examine heat input and output during high-speed temperature scanning (Non-Patent Documents 1 to 3). Further, there are international standards such as ASTM E1356-03 for reading the glass transition temperature from the DSC curve (Non-Patent Document 4).

Conventionally, when trying to prepare a sample that stopped the reaction during heat treatment, after heat treatment in a DSC or a heating furnace, quickly take it out and immerse it in a coolant such as liquid nitrogen or air cooling. was With this method, it is not possible to control the temperature delay during cooling or the processing time. It was difficult to obtain an accurate glass transition temperature due to fluctuations between measurements.

High-speed calorimetry simulates high-speed heat treatment processes in industry in analyzers, enabling investigation of thermal behavior during that process.

For polymer materials, it has been used as an effective method to investigate the heat quantity, temperature, and kinetics in the glass transition, crystallization, and melting of mainly thermoplastic resins.

C. Schick, V. Mathot, Eds., Fast Scanning Calorimetry, Springer, Switzerland (2016). Yoshitomo Furushima, Akihiko Toda, Analysis of melting behavior of polymer crystals using high-speed calorimetry, Thermal Measurement Vol.45, no.3 (2018) 106-111. Yoshitomo Furushima, Akihiko Toda, Christoph Schick, Crystallization, recrystallization, and melting of polymer crystals on heating and cooling examined with fast scanning calorimetry, Polymer Crystallization 1(2018)e10005, 1-10. ASTM E1356-03

However, there have been no reports of using FSC for the analysis of thermosetting resins. The reason for this is that, with thermosetting resins, the main purpose is often to investigate the amount of heat required for curing and the glass transition temperature of the cured product, and these values can be sufficiently detected even with a general-purpose DSC. The present invention makes it possible to measure the change in glass transition temperature during curing of thermosetting resins using rapid calorimetry.

In order to solve the above problems, the present invention has the following configuration. That is, methods for measuring the glass transition temperature of thermosetting resins using fast calorimetry, either isothermal, non-isothermal, or a combination thereof.

By applying the measurement profile in the present invention to thermosetting resin, it becomes possible to control the curing reaction, and it is possible to track the change in the glass transition temperature accompanying the progress of the reaction in real time using the same sample piece. becomes.

In the present invention, for epoxy resin, which is a typical thermosetting resin, if the temperature is raised and lowered at high speed (2000°C/s) from -80°C in the uncured state to the curing temperature (130°C for this resin), It can be confirmed that the glass transition temperature does not change. This means that the progress of curing is suppressed by performing heating and cooling at high speed. By applying this phenomenon, the progress of the reaction can be stopped by rapidly cooling the thermosetting resin to below the glass transition temperature during isothermal or non-isothermal heat treatment in the FSC. From this state, the temperature is raised again at high speed, and the glass transition temperature can be read from the FSC curve. This glass transition temperature reflects the cured state of a sample that has undergone a history of previous isothermal or non-isothermal heat treatments, and as curing progresses, the glass transition temperature increases. By repeating the cycle measurement in the order of isothermal or non-isothermal heat treatment, quenching, and reheating, it is possible to track the change in the glass transition temperature accompanying the reaction progress during the isothermal or non-isothermal heat treatment in real time. Become.

This is an example of an FSC measurement profile for confirming that the glass transition temperature does not change during high-speed heating and cooling. FIG. 1 shows the results of FSC measurement performed on an uncured epoxy resin using the measurement profile shown in FIG. It is an example of an FSC measurement profile for investigating the isothermal glass transition temperature change. FIG. 4 is a superimposition of FSC curves with different cumulative times at curing temperatures performed with the measurement profile of FIG. 3 ; FIG. It is the relationship between the isothermal time at the curing temperature and the glass transition temperature. It is an example of the FSC measurement profile for examining the non-isothermal change in the glass transition temperature. It is the change of the glass transition temperature during heating at 2°C/min.

First, as a high-speed calorimeter, one capable of heating and cooling at 10 to 10000° C./s is preferable. The isothermal setting temperature is preferably between room temperature and 300° C., and the holding time is preferably between 1 s and 6 hours depending on the conditions of the heat treatment process in material production. Non-isothermal means heating or cooling, and the scanning speed is preferably between 1° C./min and 3000° C./s depending on the conditions of the heat treatment process in material production. Air flow, nitrogen gas flow, and helium gas flow are preferable as the measurement atmosphere, and the flow rate is exemplified between 10 mL/min and 200 mL/min. By combined isothermal and non-isothermal conditions is meant alternating the isothermal and non-isothermal conditions mentioned above in line with the conditions of the heat treatment process in material production.

The objects of analysis are uncured or partially cured thermosetting resins, specifically epoxy resins, phenolic resins, urethane resins, acrylic resins, melamine resins, unsaturated polyester resins, urea resins, alkyd resins, and polyimides. Resins are preferred. Among them, epoxy resin is preferable.

The sample preparation part in the present invention is the curing conditions of the resin, and the set temperature, set time, and scanning speed can be freely set according to the type of resin. For example, for epoxy resin, the set temperature is preferably between room temperature and 300° C., and the scanning speed is between 1° C./min and 3000° C./s.

In the measurement part of the glass transition temperature in the present invention, it is preferable to cool the uncured sample to −10° C. or more lower than the glass transition temperature. When reheating, it is desirable to set the FSC curve to a temperature at which the entire stepwise signal of the glass transition can be captured, for example, up to 300°C. When the temperature is reheated, it may be higher than the temperature immediately before cooling. In that case, after measuring the temperature rise, the material is rapidly cooled to the temperature just before the cooling process. For example, epoxy resin preferably has a scanning speed of 500 to 3000° C./s.

EXAMPLES The present invention will now be described with reference to Examples. Flash DSC 1, a high-speed calorimeter manufactured by METTLER TOLEDO, was used for the measurement. The measurement atmosphere was a nitrogen gas flow of 10 mL/min.

In order to confirm that the curing reaction does not proceed during high-speed heating and cooling, FSC measurement was performed on the uncured epoxy resin using the measurement profile shown in FIG. 1. The results are shown in FIG. In this example, the curing temperature (Tiso) was 130°C, and -80°C was used as the temperature for cooling to the glass transition temperature or lower. Fig. 2 shows the FSC curve at the time of heating, and in the 1st to 20th heating and cooling cycles, the shape of the FSC curve is completely consistent, and the glass transition temperature read by the method of Non-Patent Document 4 (Tg) also match. From this result, it can be confirmed that even if the measurement is performed with the measurement profile shown in FIG. 1, the reaction does not progress enough to cause a change in Tg. The sample weight used in a series of measurements is preferably 1 μg or less, and the sample weight is calculated according to the method described in Non-Patent Document 1, 1.3.5 (from page 39). If the sample weight fluctuates, the reproducibility of the measurement results may decrease due to the effect of thermal lag. After the measurement, it is preferable to place a standard substance directly on the sample to confirm the melting start temperature and correct the temperature. High-purity indium is preferable as a reference material, and 156.6°C is used as the melting start temperature. Translate the entire curve in addition to the temperature. If it is necessary to shift the FSC curve in parallel by 10°C or more, it is preferable to disregard the measurement result and reduce the weight of the sample to half or less and re-measure. It is preferable to refer to Non-Patent Document 1 and Non-Patent Document 2 for sample weight and measurement method.

Fig. 3 shows the measurement profile of FSC at _Tiso for an arbitrary time, for example, 5 s isothermal, and Fig. 4 shows the FSC curve at the time of temperature rise. It can be confirmed that changes to the high temperature side. This means that the curing reaction proceeded by holding at a high temperature. Fig. 5 shows the relationship between Tg and Dt _total obtained from FSC measurements performed with different Tiso. It can be confirmed that the higher the temperature, the shorter the Tg rises, which means that the higher the temperature, the faster the curing progressed. FIG. 6 shows the FSC measurement profile for investigating the non-isothermal change in Tg, and FIG. 7 shows the change in Tg during heating at 2° C./min. Combining the measurement profiles of FIG. 3 and FIG. 6 to match the conditions of the heat treatment process in material production makes it possible to study the glass transition temperature changes during isothermal and non-isothermal heat treatments.

Claims (4)

Isothermal, non-isothermal, or a combination thereof , the measurement profile alternately repeats the sample preparation part and the glass transition temperature measurement part . A method for measuring the glass transition temperature of a thermosetting resin using high- speed calorimetry at 300°C and a scanning speed of 500-3000 °C/s . A method for measuring the glass transition temperature of a thermoset using rapid calorimetry according to claim 1 during curing of the thermoset. 3. The method for measuring the glass transition temperature of a thermosetting resin using high-speed calorimetry according to claim 1 or 2 , wherein the sample preparation part arbitrarily determines the set temperature, set time and scanning speed. 3. The method of measuring the glass transition temperature of a thermosetting resin using high-speed calorimetry according to claim 1 or 2 , wherein the measurement part of the glass transition temperature is carried out in a temperature range capable of capturing the entire glass transition.

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