JP6870309B2 - Wear resistance performance prediction method - Google Patents

Description

The present invention relates to a method for predicting wear resistance performance.

Rubber materials exhibit unique physical characteristics such as strength, mechanical fatigue, energy loss due to repeated deformation, and frequency responsiveness by forming a crosslinked structure in which polymers are bridged using sulfur. It is applied to seismic materials and is an indispensable material. However, in the future, there is a concern that the supply of raw materials will be insufficient due to the expansion of tire demand, etc., and it is required to maintain the performance of rubber materials for a long period of time. For that purpose, it is necessary to improve wear resistance, fracture resistance, etc. It is in.

Control of the crosslinked structure is one of the points for improving the wear resistance performance of the rubber material, and for that purpose, it is important to investigate the dispersed state of sulfur and the vulcanization accelerator. Conventionally, mapping of sulfur using fluorescent X-ray analysis (XRF), energy dispersion type X-ray spectroscopy (EDX), etc. 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 its dispersion state cannot be investigated in distinction from the vulcanization accelerator that is important for the vulcanization reaction.

An object of the present invention is to solve the above-mentioned problems, to investigate the dispersed state of a vulcanization accelerator and an additive similar thereto in a polymer composite material, and to provide a wear resistance performance prediction method for predicting wear resistance performance. ..

In the present invention, a polymer composite material containing at least one compound selected from the group consisting of a sulfide accelerator and an additive equivalent thereto is irradiated with high-intensity X-rays, and the polymer is subjected to high-intensity X-ray energy while changing the X-ray energy. The present invention relates to a wear-resistant performance prediction method for investigating the dispersed state of the compound by measuring the amount of X-ray absorption in a minute region of the composite material and predicting the wear-resistant performance based on the dispersed state.

It is preferable that the method predicts the wear resistance performance based on the particle area of the compound in the two-dimensional mapping image of the polymer composite material.
It is preferable that the method is to determine that the smaller the maximum particle area of the compound is, the better the wear resistance performance is.

It is a method of measuring the X-ray absorption amount at the sulfur L shell absorption end in the energy range of 130 to 280 eV and the X-ray absorption amount at the nitrogen K shell absorption end in the energy range of 370 to 500 eV using the high-intensity X-ray. preferable.

According to the present invention, a polymer composite material containing at least one compound selected from the group consisting of a vulcanization accelerator and an additive equivalent thereto is irradiated with high-intensity X-rays, and the X-ray energies are changed. Since it is a wear-resistant performance prediction method for investigating the dispersed state of the compound by measuring the amount of X-ray absorption in a minute region of the polymer composite material and predicting the wear-resistant performance based on the dispersed state, the tire is actually used. It is possible to predict the wear resistance performance without manufacturing a product such as the above and performing a durability test. Therefore, development time and cost can be reduced.

An example of a diagram showing a sample mapping image and an X-ray absorption spectrum. An example of a diagram showing a sample mapping image and an X-ray absorption spectrum. An example of a binarized diagram of the mapping image and a relationship diagram between the particle area and the number of vulcanization accelerator particles. An example of a relationship diagram between the maximum particle area of vulcanization accelerator particles and wear resistance performance.

In the present invention, a polymer composite material containing at least one compound selected from the group consisting of a sulfide accelerator and an additive equivalent thereto is irradiated with high-intensity X-rays, and the polymer is irradiated with high-intensity X-rays while changing the energy of the X-rays. This is a wear-resistant performance prediction method for investigating the dispersed state of the compound by measuring the amount of X-ray absorption in a minute region of the composite material and predicting the wear-resistant performance based on the dispersed state.

In order to examine the wear resistance performance, etc., the dispersed state of each vulcanization accelerator and similar additives contained in the sample (in unvulcanized rubber materials and vulcanized rubber materials, vulcanization accelerators and similar additives It is necessary to precisely observe the dispersed state, etc.).

Regarding this point, the method of the present invention first measures the amount of X-ray absorption in a minute region of a sample to measure the dispersed state of a vulcanization accelerator or an additive equivalent thereto. For example, a nitrogen K shell absorption edge. By measuring the two-dimensional mapping of NEXAFS at the sulfur L shell absorption end, it is possible to observe the dispersed state of each of the vulcanization accelerator and the additive equivalent thereto, which are important for controlling the crosslinked structure of the sample.

The method of the present invention is a method of finding that there is a relationship between the dispersed state and the wear resistance performance and predicting the wear resistance performance based on the result of the dispersed state. For example, it exists in a sample. Based on the particle size distribution of vulcanization accelerators and similar additives (distribution of areas showing vulcanization accelerators, etc. present in the cross-sectional photograph of the sample, etc.), tires and other products manufactured using the samples. It is possible to predict the wear resistance performance.

Therefore, by subjecting a polymer composite material (test piece) containing a compound such as a vulcanization accelerator to the method of the present invention, it is not necessary to actually manufacture a product such as a tire and subject it to a durability test. Abrasion resistance can be predicted.

The polymer composite material used in the method of the present invention is a material containing at least one compound selected from the group consisting of a vulcanization accelerator and an additive equivalent thereto. The vulcanization accelerator is a compound having a vulcanization promoting action that is generally added (blended) and kneaded in the kneading step of the rubber composition. An additive similar to the vulcanization accelerator is a sulfur-free vulcanizing agent (sulfur donor).

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

Examples of the additive similar to the vulcanization accelerator include 4,4'-dithiodimorpholine, 2- (4'-morpholinodithio) benzothiazole, tetramethylthiuram disulfide and the like.

The polymer composite material may contain a vulcanizing agent.
As the vulcanizing agent, those commonly used in the tire industry can be used. Sulfur vulcanizing agent (vulcanizing agent consisting of sulfur such as powdered sulfur); 1,6-hexamethylene-sodium dithiosulfate / dihydrate, Sulfur-containing vulcanizers such as 1,6-bis (N, N'-dibenzylthiocarbamoyldithio) hexane): and the like.

The polymer composite material preferably contains a diene-based polymer or a composite material in which a blended rubber material and one or more kinds of resins are composited. Examples of the diene polymer include natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene butadiene rubber (SBR), acrylonitrile butadiene rubber (NBR), chloroprene rubber (CR), butyl rubber (IIR), and halogen. Examples thereof include polymers having a double bond such as butylated 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, and examples thereof include petroleum resins such as C5-based aliphatic petroleum resins and cyclopentadiene-based petroleum resins.

The polymer composite material may be either an unvulcanized composite material or a vulcanized composite material, but particles such as a vulcanization accelerator having various particle sizes are observed, and the particle size and wear resistance are observed. It is preferable to use an unvulcanized composite material because it is easy to examine the relationship between performance.

As a method for measuring the amount of X-ray absorption in the present invention, micro XAFS (X-ray Absorption Fine Structure) or the like, 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 adopted. .. Since ordinary XAFS does not have spatial resolution, it detects the absorption amount of the entire sample, whereas micro XAFS is a measurement method for measuring the X-ray absorption spectrum in a minute region of a sample, and is usually about 100 nm or less. Has a spatial resolution of. Therefore, by adopting Micro XAFS, absorption of each vulcanization accelerator and its equivalent additives, and further vulcanization agents and the like contained in the sample is detected, and each vulcanization accelerator and its equivalent additives are detected. , Difference in absorption amount of vulcanizing agent, etc. can be detected.

From the viewpoint of excellent spatial resolution, the micro XAFS is preferably a method of measuring in a soft X-ray region (micro NEXAFS), and is preferably a scanning transmission X-ray microscope (STXM) method or an X-ray photoemission electron microscope (XPEEM). : X-ray Photoemission electron microscope) method and the like can be mentioned.

In the present invention, since the vulcanization accelerator and the like in the polymer are easily damaged by X-rays, it is desirable to measure by a method in which X-ray damage is unlikely to occur, and from this point of view, the STXM method in which X-ray damage is unlikely to occur is preferable. is there. Further, it is more preferable to prevent X-ray damage by cooling the sample at the time of measurement.

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

Then, the amount of X-ray absorption in a minute region is measured, and then the mapping image obtained by performing two-dimensional mapping of NEXAFS, the X-ray absorption spectrum of the sample site for observing the dispersed state, the vulcanization accelerator, and the like. By using the standard spectrum of each material contained in the sample such as a vulcanizing agent and a vulcanizing agent, it is possible to observe the dispersed state of each material such as the vulcanization accelerator and the vulcanizing agent and the vulcanizing agent at the site.

A continuous X-ray generator is required for the light source to scan with X-ray energy, and it is necessary to measure X-ray absorption spectra with high S / N ratio and S / B ratio in order to analyze detailed chemical states. .. Therefore, X-rays emitted from the synchrotron, since at least ^{10 10 (photons / s / mrad} 2 / mm 2 /0.1%bw) has more brightness, a and continuous X-ray source, the measurement Is optimal. Note that bw indicates the band width of X-rays emitted from the synchrotron.

High-intensity X-ray intensity ^{(photons / s / mrad 2 /} mm 2 /0.1%bw) is preferably ^{10 10} or more, more preferably ^{10 11} or more, more preferably ^{10 12} or more. The upper limit is not particularly limited, but it is preferable to use an X-ray intensity of not more than a degree that does not cause radiation damage.

Further, the photon number of the high intensity X-ray (photons / s) is preferably 10 ⁷ or more, more preferably 10 ⁹ or more. The upper limit is not particularly limited, but it is preferable to use an X-ray intensity of not more than a degree that does not cause radiation damage.

The energy range scanned using high-intensity X-rays is preferably 4000 eV or less, more preferably 1500 eV or less, and even 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.

Among them, it is preferable to scan an energy range of 370 to 500 eV to measure the amount of X-ray absorption at the nitrogen K shell absorption edge using high-intensity X-rays, and scan an energy range of 130 to 280 eV to sulfur L. It is more preferable to measure the X-ray absorption amount at the shell absorption end and to measure the X-ray absorption amount at the nitrogen K shell absorption end by scanning the energy range of 370 to 500 eV. By measuring the amount of X-ray absorption at the nitrogen K shell absorption end, it is possible to investigate the dispersion state of the vulcanization accelerator and similar additives, but at the same time, the amount of X-ray absorption at the sulfur L shell absorption end is also measured. , The dispersion of the sulfur vulcanizer can also be investigated from the same viewpoint.

The energy range of the sulfur L shell absorption end is more preferably 140 to 200 eV, and even more preferably 150 to 180 eV. The energy range of the nitrogen K shell absorption end is more preferably 375 to 450 eV, further preferably 380 to 430 eV.

Synchrotron radiation is used in the STXM method and the like, but if the energies to be measured are far apart, the optical system changes, so it is necessary to experiment with a different beamline.
The energy of each absorption edge is
[Sulfur L shell absorption end] L2 (2p1 / 2): 163.6eV, L3 (2p3 / 2): 162.5eV
[Nitrogen K shell absorption edge] 409.9 eV
[Sulfur K shell absorption edge] 2472eV
Since the energy is high only at the sulfur K shell absorption end, it is necessary to conduct separate experiments when trying to measure the sulfur K shell absorption end and the nitrogen K shell absorption end. Unless the same field of view is measured in different energy regions, the dispersion state of each material of the sulfur vulcanizer, vulcanization accelerator, and similar additives cannot be evaluated. The measurement requires experiments on different beamlines, making it difficult to measure in the same field of view. Therefore, it is basically difficult to evaluate the dispersed state of each material in the measurement.

On the other hand, if the sulfur L shell absorption end is adopted instead of the sulfur K shell absorption end, the energy range to be measured is close to that of the nitrogen K shell absorption end, and the measurement can be performed with the same device as the nitrogen K shell absorption end. Become. Therefore, the measurement can be performed in the same field of view, and the dispersed state of each material can be observed at the same time.

By using the above micro XAFS method, X-ray absorption spectrum measurement of a polymer composite material containing a vulcanization accelerator and an additive equivalent thereto is performed, and analysis is performed using two-dimensional mapping, software such as aXis2000, and the like. , The dispersed state of each vulcanization accelerator contained in the sample can be observed. Hereinafter, this point will be specifically described.

FIG. 1-1 (a) shows a mapping image of the nitrogen K shell absorption edge of a sample (a polymer composite material containing a vulcanization accelerator CZ and DPG) (upper row), an X-ray absorption spectrum of the sample (middle row), and addition. The X-ray absorption spectrum (lower) of the nitrogen K sample absorption edge of the vulcanization accelerator CZ (N-tert-butyl-2-benzothiazolyl sulphenamide) and the vulcanization accelerator DPG (1,3-diphenylguanidine) is shown. .. FIG. 1-2 (b) shows a mapping image of the sulfur L shell absorption edge of the sample (upper), an X-ray absorption spectrum of the sample (middle), a vulcanizing agent, a vulcanization accelerator CZ, and a sulfur L shell of DPG. The X-ray absorption spectrum (lower) at the absorption end is shown.

The sample is a polymer composite material (unvulcanized) prepared by kneading natural rubber, butadiene rubber, sulfur (sulfur vulcanizing agent), vulcanization accelerator CZ, vulcanization accelerator DPG and the like. First, the nitrogen K shell absorption edge is scanned in the energy range of 396 to 403 eV using a scanning transmission X-ray microscope (STXM) method to measure the X-ray absorption amount at the nitrogen K shell absorption edge, and the X-ray of the sample is measured. Obtain a line absorption spectrum. Further, two-dimensional mapping is performed on the X-ray absorption spectrum of the obtained nitrogen K shell absorption end to obtain a mapping image in the upper part of FIG. 1-1 (a).

Then, in the obtained mapping image, the amount of X-ray absorption at the nitrogen K shell absorption end of the black part of the circled part (circled part of the sample), the vulture accelerator CZ, and the X-ray at the nitrogen K shell absorption end of DPG. The amount of absorption is measured in the same energy range to obtain an X-ray absorption spectrum (middle of FIG. 1-1 (a)) of the black portion of the sample and an X-ray absorption spectrum (standard spectrum) of CZ and DPG (Fig. 1-). 1 (a) lower row).

Similarly, for the sulfur L shell absorption end at the same measurement location as the nitrogen K shell absorption end, the STXM method was used to scan the energy range of 162 to 168 eV to obtain an X-ray absorption spectrum of the sample, and the sulfur L shell was obtained. Two-dimensional mapping is performed on the X-ray absorption spectrum at the absorption edge, and the mapping image in the upper part of FIG. 1-2 (b) is obtained.

Then, in the obtained mapping image, the black part (black part 1: the part where sulfur and the sulfurization accelerator CZ are present) and the black part 2: mainly the brewing accelerator in the circled part (circled part of the sample). The amount of X-ray absorption at the sulfur L shell absorption end of CZ) and the amount of X-ray absorption of sulfur and CZ at the sulfur L shell absorption end were measured in the same energy range, and the black parts 1 and 2 of the sample were measured. An X-ray absorption spectrum (middle of FIG. 1-2 (b)) and an X-ray absorption spectrum (standard spectrum) of sulfur and CZ are obtained (lower of FIG. 1-2 (b)).

In the mapping image, the amount of X-ray absorption is larger in the black part, which indicates that sulfur or a vulcanization accelerator is present in the black part. Then, the spectrum of the nitrogen K shell absorption end of the black portion in FIG. 1-1 (a) (middle of FIG. 1-1 (a)) is compared with the standard spectrum of CZ and DPG (lower of FIG. 1-1 (a)). Then, it has a peak at the same energy as the spectra of the vulcanization accelerators CZ and DPG. Therefore, it can be seen that the vulcanization accelerators CZ and DPG are present at the site of the sample.

Similarly, the sulfur L shell absorption ends (middle of FIG. 1-2 (b)) of the black parts 1 and 2 of FIGS. 1-2 (b) are the standard spectra of sulfur and CZ (lower of FIG. 1-2 (b)). Compared with sulfur, it has a peak at the same energy as sulfur and the vulcanization accelerator CZ. Therefore, it can be seen that sulfur and the vulcanization accelerator CZ are present at the relevant portion of the sample.

Further, in the mapping image of the sulfur L shell absorption edge in the upper part of FIG. 1-2 (b), the black portion where the presence of sulfur and the vulcanization accelerator is confirmed is a granular portion with clear contrast and a portion with unclear contrast. Can be seen. On the other hand, in the mapping image of the nitrogen K shell absorption edge in the upper part of FIG. 1-1 (a), the contrast of the black portion is not clear. Therefore, it is expected that sulfur is mainly dispersed in the granular portion where the contrast is clear, and the vulcanization accelerator is mainly dispersed in the granular portion where the contrast is not clear.

Regarding the identification of the compound in the sample, if the measurement time of the spectrum is different, the energy of the spectrum may be slightly deviated (when the deviation is large, it is about 1 to 2 eV). Therefore, it is desirable to measure the spectrum and standard spectrum of the sample at the same time. For example, in the case where the standard spectrum is measured only once and the spectrum of the sample is measured at different times, the energies of both periods are tentatively deviated. Even so, it is possible to identify compounds in a sample based on the number of peaks, the energy spacing and intensity of each peak, which correspond to the standard spectrum (similar spectrum shape). is there. However, it is desirable to measure one or more standard samples for the purpose of confirming (correcting) the energy deviation. For example, since the vulcanization accelerator CZ contains both nitrogen and sulfur atoms, a method of measuring the absorption ends of the nitrogen K shell and the sulfur L shell can be used, respectively.

Further, in the case where the spectrum of the sample is close to the shape obtained by adding the standard spectra of the plurality of compounds, it can be identified that the plurality of compounds are present in the sample.

From the above analysis, it can be seen that it is possible to observe the dispersed state of the vulcanizing agent such as sulfur contained in the sample, the vulcanization accelerator, and the additive equivalent thereto. Although FIG. 1 shows an example of a polymer composite material containing a sulfur vulcanizing agent and two types of vulcanization accelerators, for example, it contains only one type of vulcanization accelerator and an additive equivalent thereto. By applying the present invention, the dispersed state of the vulcanization accelerator and similar additives can be observed in the sample as well.

The present invention is a product using a sample obtained by observing the dispersed state of a vulcanization accelerator, an additive equivalent thereto, and a vulcanizing agent such as sulfur by the above-mentioned method, and then observing the dispersed state and the dispersed state. We have found that there is a relationship with the wear resistance performance of the above, and based on this relationship, the wear resistance performance can be predicted. Hereinafter, this point will be specifically described with an example.

The mapping image of the nitrogen K shell absorption edge of the sample (polymer composite material containing vulcanization accelerators CZ and DPG) shown in the upper part of FIG. 1-1 (a) is captured by image analysis software such as Image-J. Value it and obtain the upper part of FIG. Each black part in the upper part of FIG. 1-1 (a) shows the presence of the vulcanization accelerators CZ and DPG. Therefore, it is shown that the vulcanization accelerator particles composed of the vulcanization accelerator CZ and DPG are present in each black portion in the upper part of FIG. 2, which is binarized.

Particle analysis of the vulcanization accelerator particles shown in each black part in the upper part of Fig. 2 that was binarized was performed, and the particle area (particle size, cross-sectional area of the particles) and the distribution of the number of particles having the particle area. Find (relationship). The lower part of FIG. 2 shows the particle area distribution (particle size distribution, particle cross-sectional area distribution) of each vulcanization accelerator particle existing in the upper part of FIG. 1-1 (a) obtained by the particle analysis.

^{Next, the maximum particle area (about 22 μm 2} ) of the vulcanization accelerator particles in the sample observed in the particle area distribution in the lower part of FIG. 2 and the result of the wear resistance performance (durability test) of the tire produced using the sample. FIG. 3 is an example of a diagram in which the relationship between the above and the maximum particle area of another sample and the relationship between the result of the wear resistance performance of the tire using the same are plotted. As shown in FIG. 3, the smaller the maximum particle area of the vulcanization accelerator particles, the better the wear resistance tends to be obtained. The reasons for this are (1) the dispersed state of the vulcanization accelerator may be involved in the cross-linking density, and (2) the large size of the cross-linking density (non-uniform cross-linking) provides good wear resistance. It is possible that there is no such thing.

As shown in FIG. 3, the maximum particle area of the vulcanization accelerator present in the polymer composite material ^{is preferably 10 μm 2} or less, preferably 8 μm, from the viewpoint of obtaining good wear resistance. It is more preferably ^{2 or less.}

As described above, the present invention is between the dispersed state (particle size distribution, etc.) of the vulcanization accelerator and the additives equivalent thereto in the polymer composite material and the wear resistance performance of the product such as a tire using the material. It was completed by finding the finding that there is a relationship between tires, and the wear resistance performance of the product can be predicted based on the dispersed state observed by the above-mentioned method or the like.

The present invention will be specifically described with reference to Examples, but the present invention is not limited thereto.

<Sample preparation method>
(Sample 1)
According to the following formulation, materials other than sulfur and vulcanization accelerator were filled in a Banbury type mixer so that the filling rate was 50%, and kneaded at 80 rpm until the temperature reached 140 ° C., and the obtained kneaded product was kneaded. Sulfur and a vulcanization accelerator were added in the following formulation to prepare Sample 1 (unvulcanized).

(Sample 2)
According to the following formulation, materials other than sulfur and vulcanization accelerator were filled in a Banbury type mixer so that the filling rate was 58%, and kneaded at 80 rpm until the temperature reached 140 ° C., and the obtained kneaded product was kneaded. Sulfur and a vulcanization accelerator were added in the following formulation to prepare Sample 2 (unvulcanized).

(Sample 3)
According to the following formulation, the mixture was filled in a Banbury type mixer so that the filling rate was 58%, and kneaded at 80 rpm until it reached 140 ° C. to prepare Sample 3 (unvulcanized).

(Sample 4)
The following compounding contents were kneaded with a roll to prepare Sample 4 (unvulcanized).

(Mixing)
50 parts by mass of natural rubber, 50 parts by mass of butadiene rubber, 60 parts by mass of carbon black, 5 parts by mass of oil, 2.5 parts by mass of wax, 3 parts by mass of zinc oxide, 2 parts by mass of stearic acid, 1.2 parts by mass of powdered sulfur, And 1 part by mass of vulcanization accelerator CZ, 0.5 part by mass of vulcanization accelerator DPG

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 Co., Ltd.
Oil: Process X-140 manufactured by Japan Energy Co., Ltd.
Wax: Ozo Ace 0355 manufactured by Nippon Seiro Co., Ltd.
Zinc oxide: Ginmine R manufactured by Toho Zinc Co., Ltd.
Stearic acid: Tsubaki powdered sulfur manufactured by NOF Corporation (containing 5% oil): 5% oil-treated powdered sulfur manufactured by Tsurumi Chemical Industry Co., Ltd. (soluble sulfur containing 5% by mass of oil)
Vulcanization Accelerator CZ: Noxeller CZ manufactured by Ouchi Shinko Chemical Industry Co., Ltd. (N-Cyclohexyl-2-benzothiazyl sulfenamide Vulcanization Accelerator DPG: Noxeller D manufactured by Ouchi Shinko Chemical Industry Co., Ltd. 1,3-Diphenylguanidine)

(Sampling method)
After removing the free sulfa in the sample using the method described in JP-A-2014-238287, the TEM-EDX sample is cut to a thickness of 100 nm and the STXM sample is cut to a thickness of 250 nm by a microtome, and then for TEM. Mounted on a Cu grid.

[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)
Institute for Molecular Science, Institute for Molecular Science, Extreme Ultraviolet Light Research Facility BL4U
(Measurement condition)
Brightness: 1 × 10 ¹⁶ (photons / s / mrad ² / mm ² / 0.1% bw)
Spectrometer: Grating (measured energy)
Sulfur L shell absorption end: 162-168 eV
Nitrogen K shell absorption end: 396-403 eV

[Evaluation]
For each of Example (STXM) and Comparative Example (TEM-EDX), it is possible to observe the dispersed state of sulfur (sulfur vulcanizer) and vulcanization accelerator in the sample, and to calculate the maximum particle area of the vulcanization accelerator. Was evaluated. In the examples, the maximum particle area was calculated by analyzing using aXis2000 (free software) and Image-J (free software) according to the methods of FIGS. 1 to 3. The results are shown in Tables 1-2.

<How to make a test tire>
A test tire (size: 195 / 65R15) in which the rubber compositions of Samples 1 to 4 serve as a tread portion was prepared and subjected to the following tire performance test (wear resistance).

[Tire performance test (wear resistance)]
The test tire was run on the actual vehicle, and the change in the pattern groove depth before and after the 30,000 km run was determined. The index of the wear resistance performance of the test tires produced using Sample 2 was set to 100, and the index of each test tire was calculated. The larger the index, the better the wear resistance performance.

From Table 1, the method of the comparative example using TEM-EDX can only observe the dispersed state of sulfur, whereas the method of the example using STXM can observe the dispersed state of both sulfur and the vulcanization accelerator. .. As shown in Table 2, the method of the comparative example could not calculate the maximum particle area of the vulcanization accelerator particles, whereas the method of the example could calculate it.

Then, a correlation was found between the result of the wear resistance performance test of the test tire using each sample and the maximum particle area of each sample calculated by the example, and the smaller the maximum particle area, the better the wear resistance performance. .. Therefore, according to the method of the present invention, it is possible to observe the dispersed state of the vulcanization accelerator, an additive equivalent thereto, and the vulcanizing agent such as sulfur, and to calculate the maximum particle area of the particles such as the vulcanization accelerator. , It became clear that the wear resistance performance of products using each sample can be predicted.

Claims (4)

A polymer composite material containing at least one compound selected from the group consisting of a vulcanization accelerator and an additive equivalent thereto is irradiated with high-intensity X-rays, and the minute amount of the polymer composite material is changed while changing the energy of the X-rays. A wear-resistant performance prediction method for investigating the dispersed state of the compound by measuring the amount of X-ray absorption in the region and predicting the wear-resistant performance based on the dispersed state .
The additive equivalent thereto is at least one selected from the group consisting of 4,4'-dithiodimorpholine, 2- (4'-morpholinodithio) benzothiazole, and tetramethylthiuram disulfide. .. The wear-resistant performance prediction method according to claim 1, wherein the wear-resistant performance is predicted based on the particle area of the compound in the two-dimensional mapping image of the polymer composite material. The wear-resistant performance prediction method according to claim 2, wherein it is determined that the smaller the maximum particle area of the compound is, the better the wear-resistant performance is. Claims 1 to 3 for measuring the amount of X-ray absorption at the sulfur L shell absorption end in the energy range of 130 to 280 eV and the amount of X-ray absorption at the nitrogen K shell absorption end in the energy range of 370 to 500 eV using the high-intensity X-ray. The wear resistance performance prediction method according to any one of.

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