JP2019144125A - Method for evaluating durability of nanocomposite - Google Patents

Abstract

To provide a method capable of evaluating the durability of a nanocomposite.SOLUTION: A method measures the thickness of a filler interfacial absorption polymer in a nanocomposite swollen at different degrees of swelling, so as to evaluate the durability of the nanocomposite in a non-swollen state from the relation between the degree of swelling and the thickness.SELECTED DRAWING: None

Description

The present invention relates to a method for evaluating the durability performance of a nanocomposite.

Various performances are required for nanocomposites in rubber products, etc., and in recent years, the usage period of rubber products has been prolonged, so that durability performance such as fracture resistance and wear resistance is also required. ing. It is desired to provide a method for evaluating such durability performance.

By the way, in the nanocomposite in which the filler is dispersed in the polymer, it is considered that the adhesiveness between the filler and the polymer in the interface region has a great influence on the mechanical properties of the nanocomposite. The adhesiveness between the two is considered to be related to the thickness of the polymer adsorbed on the filler surface (filler interface adsorbing polymer).

An object of the present invention is to solve the above problems and provide a method capable of evaluating the durability performance of a nanocomposite.

The present invention relates to a method for measuring the thickness of a filler interfacially adsorbed polymer in nanocomposites swelled at different degrees of swelling, and evaluating the durability performance of the nanocomposite in a non-swelled state based on the relationship between the degree of swelling and the thickness. .

The relationship between the degree of swelling Q and the thickness [delta] _Q based on a proportional constant K calculated by approximation by the following equation, it is preferable to evaluate the durability of the nanocomposite in the non-swollen state.
δ _Q = K / Q

The measurement is preferably performed by contrast-modulated small angle neutron scattering.

According to the present invention, the thickness of the filler interfacially adsorbed polymer in the nanocomposites swollen at different degrees of swelling is measured, and the durability performance of the nanocomposite in a non-swelled state is evaluated based on the relationship between the degree of swelling and the thickness. Since this is a method, the durability performance of the nanocomposite can be evaluated.

An example of an interface region model between a filler and a polymer. In an Example, the scattering intensity curve of each sample swollen to the swelling degree 2 by each of the four types of solvents having different deuteration concentrations. In an Example, the scattering intensity curve of each sample swollen to the swelling degree 4 by each of the four types of solvents having different deuteration concentrations. In an Example, the curve which approximated the relationship between the thickness and swelling degree in nanocomposite AC.

The method of the present invention measures the thickness of the filler interfacially adsorbed polymer in nanocomposites swollen to different swelling degrees, and evaluates the durability performance of the nanocomposite in a non-swelled state based on the relationship between the swelling degree and the thickness. .

When the nanocomposite is swollen with a good solvent for the polymer, the polymer adsorbed on the filler interface is less likely to swell in the solvent, while the polymer not adsorbed on the filler tends to swell in the solvent. Occurs. By using this difference in swelling degree, it is possible to quantify the thickness of the filler interface adsorption polymer in the swollen nanocomposite.

As a result of intensive studies by the inventors, it was found that the durability performance of the nanocomposite in a non-swelled state can be evaluated from the relationship between the degree of swelling of the nanocomposite and the thickness of the filler interface adsorption polymer, and the present invention has been completed. .

In particular, the present inventors have found that the degree of swelling of the nanocomposite and the thickness of the filler interfacially adsorbed polymer are generally inversely proportional, and that the larger the proportional constant is, the better the durability performance is. It was found that the durability performance of the nanocomposite in a non-swelled state can be evaluated based on the proportionality constant K calculated by approximating the relationship with _Q by the following equation.
δ _Q = K / Q

In the present invention, the filler interface adsorption polymer means a polymer having a degree of swelling higher than the degree of swelling of the polymer obtained by subtracting the volume of the filler from the volume of the solvent-swelled nanocomposite.

In the present invention, first, the thickness of the filler interfacially adsorbed polymer in the nanocomposite swollen with different degrees of swelling is measured.

A nanocomposite means a composite material in which a filler is made into particles in the order of 1 to 100 nm and dispersed in a polymer. Examples of such nanocomposites include pre-vulcanized rubber, crosslinked rubber, thermoplastic elastomer nanocomposites, thermoplastic polymer nanocomposites, thermosetting polymer nanocomposites, and the like. Among these, the method of the present invention can be suitably applied to the crosslinked rubber.

The crosslinked rubber is not particularly limited as long as it is a crosslinked rubber obtained by blending a rubber component with a filler and crosslinked with a vulcanizing agent such as sulfur, and other compounding agents (silane coupling agents widely used in the rubber industry). , Zinc oxide, stearic acid, various anti-aging agents, oils, waxes, cross-linking agents, vulcanization accelerators, and the like). Such a crosslinked rubber can be produced using a known kneading method.

As rubber components, natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene butadiene rubber (SBR), acrylonitrile butadiene rubber (NBR), chloroprene rubber (CR), butyl rubber (IIR), halogenated Examples include butyl rubber (X-IIR) and styrene isoprene butadiene rubber (SIBR). These may be used alone or in combination of two or more.

As the filler, silica, carbon black; mM ₂ · xSiO _y · zH ₂ O (wherein M ₂ is at least one metal selected from the group consisting of aluminum, calcium, magnesium, titanium and zirconium, or the metal And m represents 1 to 5, x represents 0 to 10, y represents 2 to 5, and z represents a numerical value in the range of 0 to 10.); Is mentioned. These may be used alone or in combination of two or more. Among these, the method of the present invention can be suitably applied to silica and carbon black.

Specific examples of the filler (filler) represented by the above mM ₂ · xSiO _y · zH ₂ O include aluminum hydroxide (Al (OH) ₃ ), alumina (Al ₂ O ₃ , Al ₂ O ₃ · 3H _2). O (hydrate)), clay (Al ₂ O ₃ · 2SiO ₂ ), kaolin (Al ₂ O ₃ · 2SiO ₂ · 2H ₂ O), pyrophyllite (Al ₂ O ₃ · 4SiO ₂ · H ₂ O) , Bentonite (Al ₂ O ₃ .4SiO ₂ .2H ₂ O), aluminum silicate (Al ₂ SiO ₅ , Al ₄ (SiO ₂ ) ₃ .5H ₂ O, etc.), aluminum calcium silicate (Al ₂ O ₃ .CaO) · 2SiO _2), calcium hydroxide (Ca _(OH) 2), calcium oxide (CaO), calcium silicate _(Ca 2 _SiO 4), magnesium calcium silicate (CaM SiO _4), magnesium hydroxide (Mg _(OH) 2), magnesium oxide (MgO), talc _{(MgO · 4SiO 2 · H 2} O), attapulgite _{(5MgO · 8SiO 2 · 9H 2} O), magnesium aluminum oxide (MgO · _Al 2 _O 3), titanium white _(TiO 2), include titanium black _{(Ti n O 2n-1)} and the like.

In the present invention, nanocomposites swollen with different swelling degrees are prepared and used as measurement materials. That is, for one nanocomposite whose durability is to be evaluated, a nanocomposite swollen with two or more (preferably three or more) swelling degrees is prepared and used as a measurement material. It is possible to evaluate the durability performance of the nanocomposite by using a nanocomposite swollen with different degrees of swelling as a measurement material.

The degree of swelling is defined by ((volume of swelling solvent + volume of nanocomposite) / volume of nanocomposite) −1, and the volume of swelling solvent refers to the volume of solvent stored in the nanocomposite.
For example, when a nanocomposite having a volume of 100 mm ³ is used as a nanocomposite that has been swollen to a different degree of swelling, an excessive amount of toluene is added to the nanocomposite to produce a completely swollen nanocomposite, and the complete swelling If the degree is 3, the swelled nanocomposites having a swelling degree of 1 and 2 with addition of 100 mm ³ and 200 mm ³ toluene, or the swelling degree with addition of 100 mm ³ and 300 mm ³ of toluene are 1 and 3 Swelled nanocomposites can be used.

Difference between the degree of swelling a of the nanocomposite swollen to the smallest degree of swelling and the degree of swelling b of the nanocomposite swollen to the highest degree of swelling among the nanocomposites swollen to different swelling degrees (ba) Is preferably 0.1 or more, more preferably 0.3 or more, still more preferably 1 or more, and particularly preferably 2 or more. The upper limit of the difference (b−a) is not particularly limited, but may be 5 or less and 4 or less. Within the above range, the durability performance can be evaluated with higher accuracy.

The method for swelling the nanocomposite is not particularly limited, and a known method can be used, and a method using a solvent such as toluene, cyclohexane, xylene, tetrahydrofuran or the like can be suitably used. The conditions for swelling are not particularly limited as long as the nanocomposite can uniformly swell, but it is preferable that the nanocomposite and an arbitrary amount of solvent coexist in the sealed container to uniformly swell the entire nanocomposite. To swell a nanocomposite uniformly means that the solvent used for swelling is spread throughout the nanocomposite, and the solvent is biased in the nanocomposite and does not become a warped nanocomposite. Say.

Generally, when a nanocomposite is swollen using a solvent or the like, warpage occurs in the nanocomposite. In such a warp state, the solvent or the like does not spread uniformly in the nanocomposite, and the nanocomposite and the solvent are preferably 6 hours or more, more preferably 12 hours or more, and still more preferably 24 hours or more. By coexisting, a solvent or the like can be uniformly distributed in the nanocomposite, the warp can be eliminated, and a nanocomposite in which the entire nanocomposite is uniformly swollen can be prepared.

In addition, as a method of swelling to different swelling degrees, utilizing the fact that the nano-composite is swollen with a solvent having a different SP value, the degree of complete swelling is different. A method may be used. In the method using one kind of solvent, it is necessary to add a certain amount of solvent so as to achieve the desired degree of swelling and leave it in a sealed state, but add several kinds of solvent in excess and completely swell This method is not necessary, and the degree of swelling can be changed even if the sealing performance of the sample cell is poor.

The thickness of the filler interface adsorption polymer in the swollen nanocomposite can be measured, for example, by a contrast modulation small angle neutron scattering method (CV-SANS method). One example will be specifically described.

First, the partial scattering function of each component contained in the swollen nanocomposite is obtained by the CV-SANS method. Next, curve fitting is performed on the obtained partial scattering function using an equation indicating an interface region model between the filler and the polymer, and the thickness of the filler interface adsorbing polymer is obtained.

The method for obtaining the partial scattering function of each component contained in the nanocomposite by the CV-SANS method is the same as the method described in JP2013-30286A. Details will be described.

The CV-SANS method is a technique for performing structural analysis of a plurality of substances contained in a sample from small angle neutron scattering (SANS) of a plurality of samples subjected to contrast modulation (CV). Here, contrast modulation means changing the scattering length density by changing the deuteration concentration of the solvent or the deuteration concentration of the material, and each scattering length density of a plurality of contained substances (polymer, filler, etc.) It means that the scattering length density difference (contrast), which is the difference between the two, is changed.

For example, using a solvent in which deuterated toluene and toluene are mixed at various deuterated toluene / toluene ratios as a solvent, a plurality of samples can be prepared and the CV-SANS method can be performed. What is necessary is just to measure each sample using the 4 types of solvent whose mass ratio of fluorinated toluene is 0%, 50%, 75%, and 100%. In the following, a sample having a deuterated toluene ratio (mass ratio) in the swelling solvent of 0% is “d0”, a sample of 50% is “d50”, a sample of 75% is “d75”, and a sample of 100% Is also referred to as “d100”.

FIGS. 2 and 3 show examples of scattering intensity curves of the four types of samples (d0, d50, d75, d100), respectively.

In addition, when obtaining the scattering intensity curve of each sample by the CV-SANS method, the neutron flux intensity of the neutron beam, the measuring method, the measuring device, etc. are suitably employed as described in JP-A-2014-102210. it can.

（式中、ａ_Ｐ、ａ_Ｆ、ａ_Ｓはそれぞれ、ポリマー、フィラー、膨潤溶媒の散乱長密度を表す。Ｓ_ＰＰ（ｑ）はポリマーの部分散乱関数、Ｓ_ＰＦ（ｑ）はポリマーとフィラーとの相互作用に伴う部分散乱関数、Ｓ_ＦＦ（ｑ）はフィラーの部分散乱関数を表す。ｑは下記式（２）で表わされる領域を表す。）

（式中、θは散乱角、λは中性子線の波長を表す。） The obtained sample scattering intensity curve I (q) can be expressed as the sum of the partial scattering functions of each component contained in the sample. In general, a sample of a swollen nanocomposite has a very small component fraction other than the filler, polymer, and swelling solvent, and thus can be regarded as a three-component system of filler, polymer, and swelling solvent, and the scattering intensity curve I (q ) Can be represented by the following formula (1).

(Wherein a _P , a _F and a _S represent the scattering length density of the polymer, filler and swelling solvent, respectively, S _PP (q) is the partial scattering function of the polymer, and S _PF (q) is the polymer and filler. ( _SFF (q) represents a partial scattering function of the filler, and q represents a region represented by the following formula (2).)

(In the formula, θ represents the scattering angle, and λ represents the wavelength of the neutron beam.)

（式中、Δａ_Ｐはポリマーと膨潤溶媒の散乱長密度の差、Δａ_Ｆはフィラーと膨潤溶媒の散乱長密度の差を表す。） From the respective scattering intensities I _n (q) (n = 1 to 4) of the four types of samples (d0, d50, d75, d100) and the scattering length density of each component, the partial scattering function is expressed by the following equation (3). S _PP (q), S _PF (q), and S _FF (q) can be calculated. Equation (3) is a matrix representation of Equation (1) for the four types of samples, and each partial scattering function can be determined by its singular value decomposition.

(In the formula, Δa _P represents a difference in scattering length density between the polymer and the swelling solvent, and Δa _F represents a difference in scattering length density between the filler and the swelling solvent.)

Next, an example of a method for obtaining the thickness of the filler interface adsorbing polymer by performing curve fitting on the obtained partial scattering function using an equation indicating an interface region model between the filler and the polymer will be specifically described.

（式中、Ｆ_α（ｑ）は領域αの構造振幅、Ｆ_α＋β（ｑ）は領域αと領域β全体の構造振幅、式（４）第ニ式の右辺第二項は領域γの架橋網目に由来する散乱、ξは架橋点間距離、Ｒ_ｇ，Ｆはフィラー粒子の慣性半径、Ｒ_ｇ，ａはフィラーの凝集構造の慣性半径、Ｄ_ｆは凝集構造のマスフラクタル次元を表す。Ａ〜Ｇはそれぞれフィッティングパラメーターである。） For example, a model in which an absorptive layer (region β) having a polymer volume fraction φ ₁ exists in the aggregated structure (region α) of the filler, and a matrix (region γ) having a volume fraction φ _m exists therearound (FIG. 1). See). Further, as a whole structure including the region α and the region β, a structure having a smooth radius and an inertia radius R _{g, l} is considered as a model, and a scattering function S _{α + β} (q) of this structure is considered. The obtained partial scattering functions S _PP (q), S _PF (q), and S _FF (q) are subjected to curve fitting using the following equation (4) indicating the model, and the fitting parameters are set to the least square method. Ask for.

(Where F _α (q) is the structure amplitude of the region α, F _{α + β} (q) is the structure amplitude of the region α and the entire region β, and the second term on the right side of the equation (4) is the bridging network of the region γ. , Ξ is the distance between the crosslinking points, R _{g, F} is the radius of inertia of the filler particles, R _{g, a} is the radius of inertia of the aggregate structure of the filler, and D _f is the mass fractal dimension of the aggregate structure. G is a fitting parameter.)

In the obtained fitting parameters, R _{g, l} −R _{g, a} obtained by subtracting the inertia radius R _{g, a} of the aggregate structure of the region α from the inertia radius R _{g, l of} the entire structure including the region α and the region β. Corresponds to the thickness of the filler interfacially adsorbed polymer in the nanocomposite. Thereby, the thickness of the filler interface adsorption polymer in the swollen nanocomposite can be measured.

In the present invention, the thickness δ _Q of the filler interfacially adsorbed polymer in the nanocomposites swollen with different degrees of swelling _Q is preferably determined according to the relationship between the degree of swelling Q and the thickness δ _Q. based relationship between the thickness [delta] _Q proportional constant K calculated by approximation by the following equation, to evaluate the durability of the nanocomposite in the non-swollen state.
δ _Q = K / Q

Specifically, for example, the relationship between the degree of swelling Q and the thickness δ _Q is approximated by the least square method or the like to the above equation, and the proportionality constant K is calculated, whereby the durability performance of the nanocomposite in the non-swelled state Can be evaluated.

In the present invention, the durability performance of the nanocomposite in the non-swelled state can be evaluated in this way. Thereby, it is possible to verify the relationship between the mechanical properties of the nanocomposite and greatly contribute to the development of a nanocomposite such as a rubber composition.

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

ステアリン酸：日本油脂（株）製
硫黄：鶴見化学工業（株）製の粉末硫黄
加硫促進剤１：Ｎ−ｔｅｒｔ−ブチル−２−ベンゾチアジルスルフェンアミド
加硫促進剤２：１，３−ジフェニルグアニジン Hereinafter, various chemicals used in the examples will be described together.
(Reagent used)
SBR: NS116R manufactured by Nippon Zeon Co., Ltd.
Silica: Ultrasil VN3 manufactured by Evonik
Silane coupling agent 1: Si266 (bis (3-triethoxysilylpropyl) disulfide) manufactured by Evonik
Silane coupling agent 2: Si69 (bis (3-triethoxysilylpropyl) tetrasulfide) manufactured by Evonik
Silane coupling agent 3: Y19084 (a compound represented by the following formula (I)) manufactured by Momentive

Stearic acid: Nippon Oil & Fats Co., Ltd. Sulfur: Tsurumi Chemical Co., Ltd. powder sulfur vulcanization accelerator 1: N-tert-butyl-2-benzothiazylsulfenamide vulcanization accelerator 2: 1, 3 -Diphenylguanidine

1. Preparation of nanocomposites A to C In accordance with the contents of Table 1, the ingredients except for sulfur and vulcanization accelerator were kneaded for 3 to 5 minutes in a closed Banbury mixer until the temperature reached 150 ° C. A composite was obtained. Next, the base-kneaded nanocomposite, sulfur and a vulcanization accelerator were kneaded with an open roll, and the resulting kneaded product was vulcanized to obtain nanocomposites A to C.

2. Evaluation of Fracture Energy Index The tensile strength and elongation at break of each nanocomposite were measured according to JIS-K6251 “vulcanized rubber and thermoplastic rubber—how to obtain tensile properties”. Further, the fracture energy was calculated by tensile strength × break elongation / 2. The fracture energy of the nanocomposite A is shown as an index (breaking energy index) as 100, and the results are shown in Table 3. The larger the index, the higher the fracture energy and the better the durability performance.

3. SANS measurement Four types of toluene solvents (toluene / deuterated toluene (vol / vol) = 0/100, 25/75, 50/50, 100/0) with different volume fractions of toluene and deuterated toluene. Got ready.
Each toluene solvent was dropped into each glass vial containing 15 mm square and 1 mm thick nanocomposite A so that the degree of swelling was 0.5 and left to stand overnight to obtain swollen samples A11 to A14. It was. Similarly, samples A21 to A24 swollen so that the degree of swelling was 2, and samples A31 to A34 swollen so that the degree of swelling was 4 were obtained.

Nanocomposite B of 15 mm square and 1 mm thickness was placed in each glass vial and completely immersed in each toluene solvent, and then allowed to stand overnight to obtain completely swollen samples B11 to B14. The degree of swelling was 2.6.
Nanocomposite C of 15 mm square and 1 mm thickness was placed in each glass vial and completely immersed in each toluene solvent, and then allowed to stand overnight to obtain completely swollen samples C11 to C14. The degree of swelling was 2.5.

Four types of xylene solvents (xylene / deuterated xylene (vol / vol) = 0/100, 25/75, 50/50, 100/0) with different volume fractions of xylene and deuterated xylene were prepared. .
Nanocomposite B of 15 mm square and 1 mm thickness was placed in each glass vial and completely immersed in each xylene solvent, and then allowed to stand overnight to obtain completely swollen samples B21 to B24. The degree of swelling was 3.
A nanocomposite C having a thickness of 15 mm and a thickness of 1 mm was placed in each glass vial and completely immersed in each xylene solvent, and then allowed to stand overnight to obtain completely swollen samples C21 to C24. The degree of swelling was 3.8.

Next, each swollen sample was attached to a sample holder, and the sample was irradiated with neutron beams at room temperature. Low angle detector bank data was used. The wavelength used is 1 to 10 mm. In addition, the noise data and the background from the solvent were subtracted to perform thickness correction. The scattering intensity was made absolute using glassy carbon. Thus, each scattering intensity curve I (q) was obtained.

(SANS equipment)
SANS: Ibaraki Prefectural Material Structure Analyzer (iMATERIA) attached to J-PARC
(Measurement condition)
Incident neutron wavelength: 0.2 to 10 mm
MLF beam: 300kW
(Detector)
⁵ He one-dimensional detector

From the scattering intensity curves I (q) of the samples A11 to A14 and the scattering length density of each component shown in Table 2 below, the partial scattering functions S _PP (q), S _FF (q), S _PF (q) was calculated.
Further, curve fitting was performed on these partial scattering functions using the formula (4), and the thickness of the filler interface adsorbing polymer in the nanocomposite A swollen to a degree of swelling of 0.5 was measured. It was shown in 3.

Similarly, the thickness of the filler interface adsorption polymer in the nanocomposite A swollen to the degree of swelling 2 is measured for the samples A21 to A24, and the sample in the nanocomposite A swollen to the degree of swelling 4 is measured for the samples A31 to A34. The thickness of the filler interface adsorption polymer was measured (see FIG. 2 for each of the scattering intensity curves I (q) of samples A21 to A24 and FIG. 3 for each of the scattering intensity curves I (q) of samples A31 to A34). It was shown to.

Similarly, the thickness of the filler interface adsorption polymer in the nanocomposite B swollen to a degree of swelling of 2.6 for the samples B11 to B14 was measured, and the nanocomposite B swollen to a degree of swelling of 3 for the samples B21 to B24. The thickness of the filler interfacially adsorbed polymer was measured, and the results are shown in Table 3.

Similarly, for the samples C11 to C14, the thickness of the filler interface adsorption polymer in the nanocomposite C swollen to a swelling degree of 2.5 was measured, and the samples C21 to C24 were swollen to a swelling degree of 3.8. The thickness of the filler interface adsorbing polymer in the composite C was measured, and the results are shown in Table 3.

For the nanocomposite A swollen at each degree of swelling, the filler interface adsorbed polymer thickness δ _Q is plotted against the degree of swelling Q, and approximated by the following equation using the least square method (FIG. 4) to obtain the proportionality constant k. The results are shown in Table 3.
δ _Q = K / Q

For the nanocomposite B swollen at each degree of swelling and the nanocomposite C swollen at each degree of swelling (FIG. 4), the proportionality constant k was determined in the same manner, and the results are shown in Table 3.

From Table 3, it was found that the higher the proportionality constant k, the larger the fracture energy index and the better the durability performance.

From the above, it was found that the durability performance of the nanocomposite can be evaluated by the method of the present invention.

Claims (3)

A method of measuring the thickness of a filler interfacially adsorbed polymer in nanocomposites swollen at different degrees of swelling, and evaluating the durability of the nanocomposite in a non-swelled state based on the relationship between the degree of swelling and the thickness. The relationship between the degree of swelling Q and the thickness [delta] _Q based on a proportional constant K calculated by approximation by the following equation, The method of claim 1 wherein evaluating the durability of the nanocomposite in the non-swollen state.
δ _Q = K / Q The method according to claim 1 or 2, wherein the measurement is performed by a contrast modulation small angle neutron scattering method.

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