JP2017201252A - Vulcanization material analysis method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide vulcanization material analysis method capable of observing and analyzing dispersion state and chemical state of high molecule composite material containing a vulcanizing material such as a sulfur vulcanizing agent or a vulcanization accelerator.SOLUTION: The vulcanization material analysis method for analyzing dispersion state and chemical state of each vulcanizing material by measuring X-ray absorption in a minute area of high molecule composite material while irradiating the high molecule composite material of one or two or more kinds of vulcanizing materials with a high brightness X-ray while changing the energy of the X-ray.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for analyzing vulcanized materials.

Rubber materials form unique physical properties such as strength, mechanical fatigue, energy loss due to repeated deformation, and frequency responsiveness by forming a crosslinked structure in which polymers are crosslinked using sulfur. Applied to seismic materials, it is an indispensable material.

One of the points for improving the strength, mechanical fatigue characteristics, etc. of the rubber material is the control of the cross-linking structure. For this purpose, it is important to examine the dispersion state and chemical state of sulfur and the vulcanization accelerator. Conventionally, mapping of sulfur using fluorescent X-ray analysis (XRF), energy dispersive X-ray spectroscopy (EDX) or the like has been proposed, and the dispersion state of sulfur has been analyzed. As a material, it is used together with a sulfur vulcanizing agent, and the state of dispersion cannot be examined separately from a vulcanization accelerator important for a vulcanization reaction.

In addition, since the detailed chemical state is not known in XRF and EDX, liquid chromatography-mass spectrometry (LC / MS) or pyrolysis gas chromatography-mass spectrometry (PGC) is used in order to investigate the product of the reaction. / MS) is often used. However, these methods cannot be observed in the state of rubber as it is, such as extraction into a solvent, so it is not possible to directly observe in what state the compound is dispersed, and a guideline for controlling the crosslinked structure is also determined. There is a problem that it is difficult.

As described above, the analysis methods of the dispersion state and chemical state of conventional sulfur vulcanizing agents and vulcanization accelerators still leave room for improvement, and it is desired to provide a method capable of simultaneously measuring these states. Yes.

The present invention solves the above problems and relates to a polymer composite material containing a vulcanized material such as a sulfur vulcanizing agent and a vulcanization accelerator, and can observe and analyze the dispersion state and chemical state of each vulcanized material. An object of the present invention is to provide a method for analyzing vulcanized materials.

The present invention irradiates a polymer composite material containing one or more vulcanized materials with high-intensity X-rays and changes the energy of the X-rays while changing the energy of the X-rays. The present invention relates to a vulcanized material analysis method for examining a dispersion state and a chemical state of each vulcanized material by measuring the above.

The vulcanizing material is preferably at least one selected from the group consisting of a sulfur vulcanizing agent and a vulcanization accelerator.

Using the high-intensity X-rays, measuring the X-ray absorption amount of sulfur at the sulfur L 殼 absorption edge in the energy range 130 to 280 eV and the X-ray absorption amount of nitrogen at the nitrogen K 殼 absorption edge in the energy range 370 to 500 eV. Is preferred.

According to the present invention, X-rays in a minute region of the polymer composite material are irradiated with high-intensity X-rays on the polymer composite material containing one or more vulcanized materials and the energy of the X-rays is changed. Since it is a vulcanized material analysis method for examining the dispersion state and chemical state of each vulcanized material by measuring the amount of absorption, it contains one vulcanized material such as a sulfur vulcanizing agent and a vulcanization accelerator. Not only the composite material but also a composite material containing two or more kinds can simultaneously observe and analyze the dispersion state and chemical state of each vulcanized material.

An example of the figure which shows a mapping image and an X-ray absorption spectrum.

The present invention irradiates a polymer composite material containing one or more vulcanized materials with high-intensity X-rays and changes the energy of the X-rays while changing the energy of the X-rays. This is a vulcanized material analysis method for examining the dispersion state and chemical state of each vulcanized material by measuring

In samples containing one or more vulcanized materials such as sulfur vulcanizing agents and vulcanization accelerators, the dispersion state of each vulcanized material contained in the sample (in vulcanized rubber and unvulcanized rubber) Each dispersion state of sulfur vulcanizing agent and vulcanization accelerator, etc.) and chemical state of each vulcanized material (chemical structure of vulcanization accelerator in vulcanized rubber and unvulcanized rubber, etc.) It is difficult to observe and analyze at the same time by conventional methods.

In this regard, the present invention is a method for measuring the dispersion state and chemical state of each vulcanized material by measuring the amount of X-ray absorption in a minute region of the sample. For example, the sulfur L-absorption edge, nitrogen K- By measuring the two-dimensional mapping of NEXAFS at the absorption edge, simultaneously observe the dispersion and chemical state of various vulcanizing agents (sulfur vulcanizing agents, etc.) and vulcanization accelerators that are important for controlling the cross-linking structure of the sample. It is possible to analyze.

The polymer composite material used in the method of the present invention is a material containing one or more vulcanized materials.
The vulcanized material is a material that is generally added (blended) and kneaded in the final kneading step in the kneading step of the rubber composition, and includes various vulcanizing agents (crosslinking agents), vulcanization accelerators, and the like.

As a vulcanizing agent, those generally used in the tire industry can be used, a sulfur vulcanizing agent (a vulcanizing agent composed of sulfur such as powdered sulfur), 1,6-hexamethylene-sodium dithiosulfate dihydrate, Vulcanizing agents containing sulfur such as 1,6-bis (N, N′-dibenzylthiocarbamoyldithio) hexane).

Examples of the vulcanization accelerator include various vulcanization accelerators known in the tire industry, such as guanidines, sulfenamides, thiazoles, thiurams, dithiocarbamates, thioureas, and xanthates. In particular, the method of the present invention can be suitably applied to observation and analysis of sulfur-containing vulcanization accelerators such as sulfenamides, sulfur / nitrogen-containing vulcanization accelerators further containing nitrogen.

The polymer composite material preferably includes a diene polymer or a composite material in which a blend rubber material and one or more kinds of resins are composited. Diene polymers include natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene butadiene rubber (SBR), acrylonitrile butadiene rubber (NBR), chloroprene rubber (CR), butyl rubber (IIR), halogen And polymers having a double bond such as butyl rubber (X-IIR) and styrene isoprene butadiene rubber (SIBR).

The resin is not particularly limited, and examples thereof include those widely used in the rubber industry field, and examples thereof include petroleum resins such as C5 aliphatic petroleum resins and cyclopentadiene petroleum resins.

As a method for measuring the amount of X-ray absorption in the present invention, a micro XAFS (X-ray Absorption Fine Structure), which is a method for measuring an X-ray absorption spectrum in a minute region of a sample using high-intensity X-rays, can be employed. . Since normal XAFS does not have spatial resolution, the amount of absorption of the entire sample is detected, whereas micro XAFS is a measurement method for measuring an X-ray absorption spectrum in a minute region of the sample, and is usually about 100 nm or less. It has a spatial resolution of Therefore, by adopting micro XAFS, the absorption of each vulcanizing material contained in the sample is detected, and the difference in the amount of absorption of each vulcanizing material such as sulfur vulcanizing agent, vulcanization accelerator, etc. Can be detected.

From the viewpoint of excellent spatial resolution, the micro XAFS is preferably a method of measuring in the soft X-ray region (micro NEXAFS). The scanning transmission X-ray microscope (STXM) method or the X-ray photoelectron microscope (XPEEM) : X-ray photo emission electron microscopy) method, and the like.

In the present invention, the sulfur vulcanizing agent and vulcanization accelerator in the polymer are susceptible to X-ray damage, so measurement by a method that does not easily cause X-ray damage is desirable. From this point, the STXM method is less likely to cause X-ray damage. Is preferred. Further, it is more preferable to prevent X-ray damage by cooling the sample during measurement.

The STXM method measures the amount of X-ray absorption in a minute region by irradiating a minute region of a sample with high-intensity X-rays collected by a Fresnel zone plate and measuring the light (transmitted light) that has passed through the sample and incident light. it can. Instead of the Fresnel zone plate, high-brightness X-rays may be condensed by a Kirkpatrick-Baez (KB) condensing system using an X-ray reflecting mirror.

Then, the amount of X-ray absorption in a minute region is measured, and then a mapping image obtained by performing two-dimensional mapping of NEXAFS, an X-ray absorption spectrum of a sample part to be observed and analyzed, and further sulfur By using a standard spectrum of each vulcanized material contained in a sample such as a vulcanizing agent and a vulcanization accelerator, it is possible to observe and analyze the dispersion state and chemical state of each vulcanized material at the site.

In order to scan with X-ray energy, the light source needs a continuous X-ray generator, and in order to analyze a detailed chemical state, it is necessary to measure an X-ray absorption spectrum with a high S / N ratio and S / B ratio. . Therefore, the X-rays emitted from the synchrotron have a luminance of at least 10 ¹⁰ (photons / s / mrad ² / mm ² /0.1% bw) and are continuous X-ray sources. Is the best. Note that bw represents the band width of X-rays emitted from the synchrotron.

The luminance (photons / s / mrad ² / mm ² /0.1% bw) of high-intensity X-rays is preferably 10 ¹⁰ or more, more preferably 10 ¹¹ or more, and still more preferably 10 ¹² or more. Although an upper limit is not specifically limited, It is preferable to use the X-ray intensity below the extent that there is no radiation damage.

The number of photons (photons / s) of the high-intensity X-ray is preferably 10 ⁷ or more, more preferably 10 ⁹ or more. Although an upper limit is not specifically limited, It is preferable to use the X-ray intensity below the extent that there is no radiation damage.

The energy range scanned using high-intensity X-rays is preferably 4000 eV or less, more preferably 1500 eV or less, and still more preferably 1000 eV or less. If it exceeds 4000 eV, the target polymer composite material may not be analyzed. The lower limit is not particularly limited.

In particular, using high-intensity X-rays, the energy range of 130 to 280 eV is scanned to measure the amount of sulfur X-ray absorption at the sulfur L-absorption edge, and the energy range of 370 to 500 eV is scanned to detect nitrogen K. It is preferable to measure the amount of X-ray absorption of nitrogen at the soot absorption edge. Thus, measuring the sulfur L soot absorption edge and the nitrogen K soot absorption edge is one of the points of the present invention. In addition, the energy range of the sulfur L soot absorption end is more preferably 140 to 200 eV, and further preferably 150 to 180 eV. The energy range of the nitrogen K 殼 absorption edge is more preferably 375 to 450 eV, and further preferably 380 to 430 eV.

In the STXM method or the like, synchrotron radiation is used. However, when the energy to be measured is far away, the optical system changes, so it is necessary to conduct experiments with another beam line.
The energy at each absorption edge is
[Sulfur L soot absorption end] L2 (2p1 / 2): 163.6 eV, L3 (2p3 / 2): 162.5 eV
[Nitrogen K 殼 absorption edge] 409.9 eV
[Sulfur K 殼 absorption edge] 2472eV
Since only the sulfur K 硫黄 absorption edge has high energy, it is necessary to experiment separately when trying to measure the sulfur K 殼 absorption edge and the nitrogen K 殼 absorption edge. And unless the same field of view is measured in different energy regions, the dispersion state and chemical state of each vulcanized material such as sulfur vulcanizing agent and vulcanization accelerator cannot be evaluated, so sulfur K 殼 absorption edge and nitrogen K 窒 素 absorption Edge measurement requires experimentation with a separate beamline and cannot be measured in the same field of view. Therefore, this measurement cannot evaluate the dispersion state or chemical state of each vulcanized material.

On the other hand, if the sulfur L soot absorption end is used instead of the sulfur K soot absorption end, the energy range to be measured is close to the nitrogen K soot absorption end, and measurement with the same apparatus as the nitrogen K soot absorption end is possible. Become. Therefore, measurement in the same visual field becomes possible, and the dispersion state and chemical state of each vulcanized material can be observed and analyzed simultaneously.

Using the above-mentioned micro XAFS method, X-ray absorption spectrum measurement of a polymer composite material containing one or more vulcanized materials is performed and analyzed by two-dimensional mapping, etc. The dispersion state and chemical state of each vulcanized material can be observed and analyzed simultaneously. Hereinafter, this point will be specifically described.

FIG. 1A shows a mapping image (upper) of a nitrogen K 殼 absorption edge of a sample (a polymer composite material containing two or more vulcanized materials), the sample, a vulcanization accelerator TBBS (N-tert -Butyl-2-benzothiazolylsulfenamide) and an X-ray absorption spectrum (lower part) of the nitrogen K 殼 absorption edge of vulcanization accelerator M (2-mercaptobenzothiazole). FIG. 1 (b) shows a mapping image (upper stage) of the sulfur L soot absorption edge of the sample, and X of the sulfur L soot absorption edge of the sample, sulfur vulcanizing agent, vulcanization accelerator TBBS, and vulcanization accelerator M. A linear absorption spectrum (lower part) is shown.

The sample is a polymer composite material prepared by kneading and vulcanizing isoprene rubber, sulfur (sulfur vulcanizing agent), and vulcanization accelerator TBBS. First, with respect to the nitrogen K に つ い て absorption edge, the X-ray absorption amount of nitrogen at the nitrogen K エ ネ ル ギ ー absorption edge is measured by scanning the energy range of 396 to 403 eV using a scanning transmission X-ray microscope (STXM) method. X-ray absorption spectrum of is obtained. Further, two-dimensional mapping is performed on the obtained X-ray absorption spectrum of the nitrogen K 殼 absorption edge to obtain the upper mapping image in FIG.

And the X-ray absorption amount of nitrogen at the nitrogen K 殼 absorption end of the circled portion (circled portion of the sample), the vulcanization accelerator TBBS, and the vulcanization accelerator M in the black part of the mapping image obtained is the same energy. Measurement is performed within a range, and an X-ray absorption spectrum of the corresponding portion of the sample, an X-ray absorption spectrum (standard spectrum) of TBBS, and M are obtained (the lower part of FIG. 1A).

Similarly, the sulfur L 殼 absorption edge at the same measurement location as the nitrogen K 殼 absorption edge is similarly scanned using the STXM method to obtain an X-ray absorption spectrum of the sample by scanning the energy range of 162 to 168 eV. Two-dimensional mapping is performed on the X-ray absorption spectrum at the absorption edge to obtain the upper mapping image in FIG. Similarly, the X-ray absorption amount of sulfur at a circle L (absorbed point of sample), sulfur, TBBS, and sulfur L 殼 absorption edge of sulfur in the same energy range is measured, An X-ray absorption spectrum (standard spectrum) of an absorption spectrum, sulfur, TBBS, and M is obtained (the lower part of FIG. 1 (b)).

In the mapping image, the X-ray absorption amount is larger in the black portion, which indicates that sulfur or a vulcanization accelerator is present in the black portion. And when the spectrum of the nitrogen K 殼 absorption edge of the circled part (sample) of the black part is compared with the standard spectrum (TBBS, M) (the lower part of FIG. 1 (a)), the same energy as the spectrum of the vulcanization accelerator M is obtained. Has a peak. Therefore, it is shown that the vulcanization accelerator M is present in the corresponding portion of the sample, and it can be seen that the vulcanization accelerator TBBS blended in the sample is changed to the vulcanization accelerator M by the vulcanization reaction.

Similarly, when the sulfur L soot absorption edge of the encircled part (sample) is compared with the standard spectrum (sulfur, TBBS, M) (the lower part of FIG. 1 (b)), it peaks at the same energy as sulfur and vulcanization accelerator M. have. Therefore, it turns out that sulfur and the vulcanization accelerator M exist in the said location of a sample.

Furthermore, in the mapping image of the sulfur L soot absorption edge in the upper part of FIG. 1 (b), the black part where the presence of sulfur and the vulcanization accelerator M is confirmed includes a granular part with clear contrast and a part with unclear contrast. It can be seen. On the other hand, in the mapping image of the nitrogen K 殼 absorption edge in the upper part of FIG. 1A, the contrast of the black part is not clear. Therefore, it can be considered that sulfur is dispersed in the granular portion where the contrast is clear, and the vulcanization accelerator is dispersed in the portion where the contrast is not clear.

Through the analysis described above, it is possible to observe the dispersion state of sulfur and vulcanization accelerator contained in the sample, and the vulcanization accelerator TBBS is changed to the vulcanization accelerator M by the vulcanization reaction of the sample. It can be seen that it is possible to identify the compound present in the sample (identify the chemical structure) by analyzing the chemical state of sulfur and the vulcanization accelerator, such as changed points. Further, FIG. 1 shows an example of a polymer composite material containing two or more kinds of vulcanizing materials. For example, the present invention can be applied to a sample containing one kind of sulfur as a vulcanizing material. Similarly, the dispersion state and chemical state of sulfur can be observed and analyzed.

Therefore, according to the present invention, for vulcanized and unvulcanized polymer composite materials containing one or more vulcanized materials, the dispersion state and chemical state of each vulcanized material before and after vulcanization are determined. It becomes possible to observe and analyze at the same time.

In the above, examples of vulcanized materials such as a sulfur vulcanizing agent and a vulcanization accelerator have been given. However, the oxygen K 殼 absorption edge (absorption edge energy: 543.1 eV) is similarly applied to NEXAFS 2 By measuring the dimensional mapping, the dispersion of ZnO in the sample can be observed and analyzed simultaneously.

The present invention will be specifically described based on examples, but the present invention is not limited to these examples.

(Sample preparation method)
In accordance with the following blending contents, materials other than sulfur and vulcanization accelerator were charged into a 1.7 L Banbury mixer manufactured by Kobe Steel Co., Ltd. so that the filling rate was 58%, and until reaching 140 ° C. at 80 rpm. Kneaded (Step 1). A rubber sample was obtained by adding sulfur and a vulcanization accelerator to the kneaded product obtained in step 1 in the following composition and vulcanizing at 160 ° C. for 20 minutes (step 2).

(Combination)
Natural rubber 50 parts by mass, butadiene rubber 50 parts by mass, carbon black 60 parts by mass, oil 5 parts by mass, anti-aging agent 2 parts by mass, wax 2.5 parts by mass, zinc oxide 3 parts by mass, stearic acid 2 parts by mass, powder 1.2 parts by mass of sulfur and 1 part by mass of vulcanization accelerator

The materials used are as follows.
Natural rubber: TSR20
Butadiene rubber: BR150B manufactured by Ube Industries, Ltd.
Carbon Black: Show Black N351 manufactured by Cabot Japan
Oil: Process X-140 manufactured by Japan Energy Co., Ltd.
Anti-aging agent: NOCRACK 6C (N-1,3-dimethylbutyl-N′-phenyl-p-phenylenediamine) manufactured by Ouchi Shinsei Chemical Co., Ltd.
Wax: Ozoace 0355 manufactured by Nippon Seiwa Co., Ltd.
Zinc oxide: Silver candy R made by Toho Zinc Co., Ltd.
Stearic acid: Koji powder sulfur manufactured by NOF Corporation (containing 5% oil): 5% oil-treated powder sulfur manufactured by Tsurumi Chemical Co., Ltd. (soluble sulfur containing 5% by mass of oil)
Vulcanization accelerator: Noxeller NS-P (N-tert-butyl-2-benzothiazolylsulfenamide) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.

(Sampling method)
After removing free sulfur in the sample using the method described in Japanese Patent Application Laid-Open No. 2014-238287, the sample for TEM-EDX was cut to a thickness of 100 nm and the sample for STXM was cut to a thickness of 250 nm by a microtome. It was mounted on a grid made of Cu.

[Comparative Example]
The prepared sample was subjected to TEM-EDX measurement (using a commercially available device).

〔Example〕
The prepared sample was subjected to STXM measurement under the following conditions.
(Measurement location)
National Institute for Natural Sciences Molecular Science Laboratory Extreme Ultraviolet Light Research Facility BL4U
(Measurement condition)
Luminance: 1 × 10 ¹⁶ (photons / s / mrad ² / mm ² /0.1% bw)
Spectrometer: Grating (measurement energy)
Sulfur L soot absorption edge: 162-168eV
Nitrogen K 殼 absorption edge: 396 to 403 eV

[Evaluation]
For each of the example (STXM) and the comparative example (TEM-EDX), it is possible to observe the dispersion state of the sulfur (sulfur vulcanizing agent) and the vulcanization accelerator in the sample and analyze the chemical state as follows. Evaluated by criteria. In the examples, observation and analysis were performed using the method of FIG.
○: Possible ×: Impossible

The method of the comparative example by TEM-EDX can only observe the dispersion state of sulfur, while the method of the embodiment by STXM can identify the compound by observation of the dispersion state and chemical state analysis for both sulfur and vulcanization accelerator. It was possible. In particular, N-tert-butyl-2-benzothiazolylsulfenamide blended as a raw material vulcanization accelerator was changed to 2-mercaptobenzothiazole in the sample (vulcanized rubber) according to Examples. found. Therefore, it became clear that the dispersion state and chemical state of the vulcanized material can be observed and analyzed by the method of the present invention.

Claims (3)

Irradiating a polymer composite material containing one or two or more vulcanized materials with high-intensity X-rays and measuring the X-ray absorption in a minute region of the polymer composite material while changing the energy of the X-rays A vulcanized material analysis method for investigating the dispersion state and chemical state of each vulcanized material. The vulcanization material analyzing method according to claim 1, wherein the vulcanization material is at least one selected from the group consisting of a sulfur vulcanizing agent and a vulcanization accelerator. Using the high-intensity X-ray, the X-ray absorption amount of sulfur at the sulfur L 殼 absorption edge in the energy range of 130 to 280 eV and the X-ray absorption amount of nitrogen at the nitrogen K 殼 absorption edge in the energy range of 370 to 500 eV are measured. Item 3. The vulcanized material analysis method according to Item 1 or 2.