JPH03242525A - Measurement of hardness for ultraviolet ray curing type resin - Google Patents

Abstract

PURPOSE:To judge a state of hardening of an UV curing type resin accurately by determining active energy of the resin from a dielectric relaxation spectrum of the ultraviolet (UV) curing type resin to learn a degree of hardness of the UV curing type resin from a value of the activation energy obtained. CONSTITUTION:A dielectric relaxation spectrum of an UV curing type resin is measured to determine activation energy of the resin from the dielectric relaxation spectrum. The activation energy and a degree of hardening of the UV curing type resin is in a fixed relationship. Thus, a relationship between the degree of hardening of the UV hardening type resin and the activation energy is determined previously to compare data thereof with the activation energy of a sample measured thereby enabling the learning of the degree of hardening of the sample.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an ultraviolet curable resin (hereinafter abbreviated as tJV curable resin) used as a coating material for optical fibers.
This article relates to a method for measuring the degree of hardening of tJV curable resin, which allows the degree of hardening of tJV to be accurately determined.

``Conventional Techniques'' Conventionally, UV-curable resins have been used as coatings for optical fibers. This change in physical properties has a great effect on the transmission characteristics and other properties of the optical fiber coated with the UV curable resin described in Section 2. Therefore, the transmission characteristics of the optical fiber, etc. In order to stabilize the various properties of the UV curable resin, it is necessary to maintain a constant degree of curing. What is important to understand?

``Problems to be Solved by the Invention'' However, in general, as a method for quantitatively understanding the state of curing of a curable resin, measuring Kel fraction, viscoelasticity, or tensile strength, etc. -+, etc. Is there a way to understand the curing state of UV-curable tree buds?

However, if l is S, then this is a method that has the following shortcomings.

The measurement time is long and the measurement operation is complicated.

■The measurement variation is large.

(2) It is not possible to cover an optical fiber and measure it in the f2 state, and it is necessary to use a resin alone for measurement.

■There are methods that measure the hardening state macroscopically, and there is no molecular basis.

Therefore, when attempting to determine the degree of curing of a UV curable resin using such a method, there is a problem in that the state of curing of the UV curable resin cannot be accurately determined due to the large variation in measurement described above.

In addition, in the conventional method described above, the UV curable resin coats the optical fiber and cannot be measured on a sample with a two-dimensional shape.
It is necessary to separate the curable resin from the optical fiber, which is inconvenient as it takes time to collect the sample.

The present invention was made in view of the above circumstances, and it is a measuring method that can accurately determine the degree of hardening of hardened wood, and also has a simple measuring method and a short measuring time. The object of the present invention is to provide a method for measuring the degree of curing of a curable resin, which is short and easy to take, especially just one sample.

"Means for Solving the Problem" In the present invention, the dielectric relaxation spectrum of the UV curable resin is used to determine the activation energy of the resin, and the degree of curing of the UV curable resin is determined from the value of the obtained activation energy. By knowing this, I tried to solve the above problem.

Hereinafter, the method for measuring the degree of curing of UV curable resin according to the present invention will be explained in detail.

As mentioned above, the method of measuring the degree of curing of the UV curable resin of the present invention is characterized by measuring the dielectric relaxation spectrum of the UV curable resin, calculating the activation energy of the resin based on this dielectric relaxation spectrum, and calculating the activation energy of the resin. UV from activation energy value
It is important to know the degree of curing of the curable resin.

The measurement of the dielectric relaxation spectrum of the UV curable resin coating the fiber is performed using a commercially available dielectric relaxation spectrum measuring device. Mafko, U used for this measurement
As the sample of the V-curable resin, a sample in which an optical fiber is coated with the same-curable resin, a sample in which the UV-curable resin is peeled off from the optical fiber, or a separately prepared sample is used.

As a specific method for measuring the above dielectric relaxation spectrum, first, select several sample temperatures in the range of 20 to 150°C, and at each selected temperature, change the frequency of the alternating electric field to 11 (z - Measure the dielectric loss at that frequency while varying it in the range of GHz.In the graph of frequency and dielectric loss obtained by this measurement, the dielectric loss shows a peak value at a certain frequency.This dielectric loss The frequency showing the peak value (hereinafter referred to as maximum relaxation frequency) is measured at each measurement temperature.

A dielectric relaxation spectrum can be obtained from the relationship between the six measured temperatures obtained in this way and the maximum relaxation frequency. Figure 1 shows this dielectric relaxation spectrum.
("K) indicates the measurement temperature, and fm (Hz) indicates the maximum relaxation frequency.

Next, from this dielectric relaxation spectrum, the activation energy (
A method for calculating Ea) will be explained.

First, the relationship between the reaction rate constant (k) of dielectric relaxation and the activation energy (Ea) is expressed as follows from the Arrhenius equation.

in k --(Ea/R)・T-'ten In A (
1) Here, A is a pre-exponential factor, T is an absolute temperature, and R is a gas constant.

Also, the reaction constant (&) of dielectric relaxation and the maximum relaxation frequency fm
(Hz) is expressed as k=2π·fm (2).

By substituting equation (2) into equation (1) above, the following equation is derived.

in rm--(Ea/R)・T-'-In B (
3) As if this equation (3) is not correct, the slope of the straight line showing the relationship between In fm and T -1 shown in Fig. 1, or -(E a/R) in equation (3) handle.

In this way, the slope of the dielectric relaxation spectrum shown in FIG. 1 and the activation energy (Ea) can be calculated.

Next, the activation energy obtained in this way and U
The relationship with the degree of curing of the V-curable resin will be explained.

In the early stages of curing of UV-curable resins, the probability of the presence of other polymer chains that inhibit the segment movement of the UV-curable resin is small, so the segments can move relatively freely. be. In other words, this molecular movement can be performed with relatively small activation energy.

However, as the curing of the LIV curable resin progresses, the probability (frequency) of the segment movement being constrained by other polymer chains increases, so larger activation energy is required to perform the same segment movement. becomes.

In this way, there is a certain relationship between the activation energy and the degree of grouping of the TJV curing resin. Therefore, by determining the relationship between the degree of curing and activation energy of the V-curing resin in advance, and comparing that data with the measured sample and activation energy, the degree of curing of the sample can be determined. Do what you know.

Example Several samples consisting of optical fibers (fiber diameter φ125μx, UV coating diameter φ250μg) coated with diurethane acrylate-based UV curable resin were prepared, and each sample was exposed to different amounts of UV irradiation. , the dielectric relaxation spectrum of each sample was measured, and the activation energy (Ea) was calculated.

Second, the gel fraction was also measured for the samples subjected to UV irradiation in the above-mentioned amounts. FIG. 2 shows the measurement results, that is, the relationship between the amount of ultraviolet irradiation and the gel fraction and activation energy of the resin at that amount of irradiation. Here, the curve indicated by the symbol A in the figure shows the radiation dose and activation energy (Ea).
The curve shown by symbol B shows the relationship between the irradiation amount and the gel fraction.

From Figure 2, it can be seen that in this resin, curing of the UV curable resin is completed at an irradiation dose of 500 mJ/am3 from the measurement data of the gel fraction, but the activation energy From the measurement data of (E a), it is 1000 m.
It is determined that curing is completed at an irradiation dose of J/am3. In other words, this resin has an appearance of 500
Although curing appears to be completed with an ultraviolet radiation dose of mJ/Cm3, molecular theory shows that an ultraviolet heat radiation dose of 10100 O/Cm3 is required, which is the saturation value for constraining segment motion.

"Effects of the Invention" As explained above, the present invention calculates the activation energy of a UV curable resin from the dielectric relaxation spectrum of the resin, and calculates the degree of curing of the UV curable resin from the value of the obtained activation energy. Since the method for measuring the degree of curing of an ultraviolet curable resin is characterized by knowing the following, the value of the activation energy calculated is also accurate since the measurement accuracy of the l-th dielectric relaxation vector is high. Therefore, by using this activation energy, the degree of curing of the UV curable resin can be accurately determined.

Furthermore, measurement can be performed using UV-curable resin that coats an optical fiber and is in the f-state, and the measurement method is simple and the measurement time is short, making it easy to prepare a measurement sample and measure the sample in a short time. can. Furthermore, the degree of curing of the UV curable resin can be determined based on molecular weight theory.

Therefore, the present invention has the effect that the degree of curing of a UV curable resin can be determined accurately and quickly in the manufacturing process and the like based on molecular weight theory.

[Brief explanation of drawings]

FIG. 1 is a graph showing the dielectric relaxation spectrum used in the present invention, and FIG. 2 is a graph showing the relationship between the UV irradiation amount, the activation energy of the resin, and the gel fraction in Examples of the present invention.

Claims (1)

[Claims] The method is characterized in that the dielectric relaxation spectrum of the ultraviolet curable resin is measured, the activation energy of the resin is determined from the dielectric relaxation spectrum, and the degree of curing of the ultraviolet curable resin is determined from the value of the obtained activation energy. Method for measuring degree of curing of ultraviolet curable resin.