Organic-inorganic composite for rubber reinforcement, method for preparing the same, and rubber composition for tires comprising the same

Abstract

The present disclosure relates to an organic-inorganic composite for rubber reinforcement, a method for preparing the same, and a rubber composition for tires including the same. The organic-inorganic composite for rubber reinforcement according to the present disclosure exhibits excellent dispersibility in the rubber composition and reinforcing effect, and thus can be suitably used for eco-friendly tires requiring high efficiency and high fuel efficiency characteristics.

Claims

1. An organic-inorganic composite for rubber reinforcement, comprising: amorphous aluminosilicate particles having a composition of the following Chemical Formula 1, and a silane-based coupling agent bonded to at least a part of a surface of aluminosilicate particles, wherein the organic-inorganic composite satisfies the following Equation 1:
M.sub.x/n[(AlO.sub.2).sub.x,(SiO.sub.2).sub.y].m(H.sub.2O)[Chemical Formula 1] wherein, in Chemical Formula 1, M is an element selected from the group consisting of Li, Na, K, Rb, Cs, Be, and Fr, or an ion thereof; x>0, y>0, n>0, and m0; 1.0y/x10.0; and 0.01x/n1.2;
Da3.0[Equation 1] wherein, in Equation 1, Da is an area under a derivative thermogravimetric curve over a temperature range of 300 C. to 500 C., wherein the derivative thermogravimetric curve is in units weight reduction percent of the organic-inorganic composite relative to temperature (%/ C.), and wherein the derivative thermogravimetric curve is obtained from thermogravimetric analysis (TGA) of the organic-inorganic composite, wherein, in TGA, weight of the organic-inorganic composite is measured as a function of temperature over a temperature ranging from 30 C. to 500 C.

2. The organic-inorganic composite for rubber reinforcement of claim 1, wherein the amorphous aluminosilicate particles have an average particle diameter of 10 to 100 nm, a Brunauer-Emmett-Teller surface area (S.sub.BET) of 80 to 250 m.sup.2/g, and an external specific surface area (SExT) of 60 to 200 m.sup.2/g according to an analysis of nitrogen adsorption/desorption.

3. The organic-inorganic composite for rubber reinforcement of claim 1, wherein the silane-based coupling agent is at least one compound selected from the group consisting of bis(3-triethoxysilylpropyl) tetrasulfide, bis(2-triethoxysilylethyl) tetrasulfide, bis(4-triethoxysilylbutyl) tetrasulfide, bis(3-trimethoxysilylpropyl) tetrasulfide, bis(2-trimethoxysilylethyl) tetrasulfide, bis(4-trimethoxysilylbutyl) tetrasulfide, bis(3-triethoxysilylpropyl) trisulfide, bis(2-triethoxysilylethyl) trisulfide, bis(4-triethoxysilylbutyl) trisulfide, bis(3-trimethoxysilylpropyl) trisulfide, bis(2-trimethoxysilylethyl) trisulfide, bis(4-trimethoxysilylbutyl) trisulfide, bis(3-triethoxysilylpropyl) disulfide, bis(2-triethoxysilylethyl) disulfide, bis(4-triethoxysilylbutyl) disulfide, bis(3-trimethoxysilylpropyl) disulfide, bis(2-trimethoxysilylethyl) disulfide, bis(4-trimethoxysilylbutyl) disulfide, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyltetrasulfide, 3-triethoxysilylpropyl-N,N-dimethylthiocarbamoyltetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyltetrasulfide, 2-trimethoxysilylethyl-N,N-dimethylthiocarbamoyltetrasulfide, 3-trimethoxysilylpropylbenzothiazolyltetrasulfide, 3-triethoxysilylpropyl benzothiazole tetrasulfide, 3-trimethoxysilylpropyl methacrylate monosulfide, and 3-trimethoxysilylpropyl methacrylate monosulfide.

4. A method for preparing an organic-inorganic composite for rubber reinforcement, comprising: mixing and heating amorphous aluminosilicate particles and an organic solvent to a temperature ranging from 130 to 150 C. to prepare a heated mixture, wherein the amorphous aluminosilcate particles have a composition represented by Chemical Formula 1; adding a silane-based coupling agent to the heated mixture and stirring for 10 to 60 minutes to form an organic-inorganic composite having the silane-based coupling agent bound to at least a part of a surface of the amorphous aluminosilicate particles; and washing and drying the organic-inorganic composite, wherein the organic solvent having a boiling point of 150 C. or higher and not reactive with the amorphous aluminosilcate particles and the silane-based coupling agent, wherein the organic-inorganic composite satisfies the following Equation 1:
M.sub.x/n[(AlO.sub.2).sub.x,(SiO.sub.2).sub.y].m(H.sub.2O)[Chemical Formula 1] wherein, in Chemical Formula 1, M is an element selected from the group consisting of Li, Na, K, Rb, Cs, Be, and Fr, or an ion thereof; x>0, y>0, n>0, and m0; 1.0y/x10.0; and 0.01x/n1.2;
Da3.0[Equation 1] wherein, in Equation 1, Da is an area under a derivative thermogravimetric curve over a temperature range of 300 C. to 500 C., wherein the derivative thermogravimetric curve is in units weight reduction percent of the organic-inorganic composite relative to temperature (%/ C.), and wherein the derivative thermogravimetric curve is obtained from thermogravimetric analysis (TGA) of the organic-inorganic composite, wherein, in TGA, weight of the organic-inorganic composite is measured as a function of temperature over a temperature ranging from 30 C. to 500 C.

5. The method for preparing the organic-inorganic composite for rubber reinforcement of claim 4, wherein a weight ratio of the amorphous aluminosilicate particles and the silane-based coupling agent ranges from 1:0.01 to 1:0.5.

6. The method for preparing the organic-inorganic composite for rubber reinforcement of claim 4, wherein the organic solvent is at least one compound selected from the group consisting of mesitylene, indane, tetralin, limonene, decane, undecane, and dodecane.

7. A rubber composition for tires, comprising: the organic-inorganic composite for rubber reinforcement of claim 1; and at least one diene elastomer.

8. The rubber composition for tires of claim 7, wherein the diene elastomer is at least one compound selected from the group consisting of a natural rubber, polybutadiene, polyisoprene, a butadiene/styrene copolymer, a butadiene/isoprene copolymer, a butadiene/acrylonitrile copolymer, an isoprene/styrene copolymer, and a butadiene/styrene/isoprene copolymer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a graph showing a derivative thermogravimetric curve obtained by thermogravimetric analysis (TGA) of the organic-inorganic composite of Example 1.

(2) FIG. 2 is a graph showing a derivative thermogravimetric curve obtained by thermogravimetric analysis (TGA) of the organic-inorganic composite of Example 2.

(3) FIG. 3 is a graph showing a derivative thermogravimetric curve obtained by thermogravimetric analysis (TGA) of the organic-inorganic composite of Comparative Example 1.

(4) FIG. 4 is a graph showing a derivative thermogravimetric curve obtained by thermogravimetric analysis (TGA) of the organic-inorganic composite of Comparative Example 2.

(5) FIG. 5 is a graph showing a derivative thermogravimetric curve obtained by thermogravimetric analysis (TGA) of the organic-inorganic composite of Control Example.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(6) Hereinafter, preferred examples are provided for better understanding. However, these examples are for illustrative purposes only, and the invention is not intended to be limited by these examples.

Synthesis Example 1

(7) (Preparation of Amorphous Aluminosilicate Particles)

(8) 23 g of KOH (Daejung Chemicals & Metals) and 27 g of colloidal silica (Ludox HS 30 wt %, Sigma-Aldrich) were completely dissolved in 22 ml of distilled water (DW). 15 g of metakaolin (Al.sub.2Si.sub.2O.sub.7, Aldrich) was added to the solution, followed by mixing at 600 rpm for 40 minutes using an overhead stirrer.

(9) This was cured at a temperature of about 70 C. for 4 hours.

(10) The cured solid product was added into distilled water at 90 C., stirred for 12 hours, and centrifuged to wash it to about pH 7.

(11) The washed solid product was dried in an oven at 70 C. for 24 hours to finally obtain aluminosilicate particles (primary particle diameter of 30 nm).

Synthesis Example 2

(12) (Preparation of Crystalline Aluminosilicate Particles)

(13) 12 g of NaOH (Daejung Chemicals & Metals) and 31 g of a Na.sub.2SiO.sub.5 solution (Aldrich) were completely dissolved in 22 ml of distilled water (DW). 15 g of metakaolin (Al.sub.2Si.sub.2O.sub.7, Aldrich) was added to the solution, followed by mixing at 800 rpm for 40 minutes using an overhead stirrer.

(14) This was cured at room temperature of about 25 C. for 24 hours.

(15) The cured product was added into distilled water at 90 C., stirred for 12 hours, and centrifuged to wash it to about pH 7.

(16) The washed solid product was dried in an oven at 70 C. for 24 hours to finally obtain aluminosilicate particles (primary particle diameter of 150 nm).

Experimental Example 1

(17) (1) The average particle diameter and composition of the aluminosilicate particles according to Synthesis Examples 1 and 2 were confirmed using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS).

(18) As a result, it was confirmed that the aluminosilicate particles of Synthesis Example 1 had a composition of y/x=1.6 and x/n=1.12 in Chemical Formula 1. Also, it was confirmed that the aluminosilicate particles of Synthesis Example 2 had a composition of y/x=1.31 and x/n=0.91 in Chemical Formula 1.

(19) (2) The nitrogen adsorption/desorption Brunauer-Emmett-Teller surface area (S.sub.BET) and the external specific surface area (S.sub.EXT) were measured for the particles according to Examples 1 and 2 using a specific surface area analyzer (BEL Japan Inc., BELSORP_MAX). Then, the volume of micropores (V.sub.micro) having a pore size of less than 2 nm was calculated from the S.sub.BET by a t-plot method.

(20) TABLE-US-00001 TABLE 1 Primary particle diameter S.sub.BET S.sub.EXT V.sub.micro (nm) (m.sup.2/g) (m.sup.2/g) S.sub.EXT/S.sub.BET (cm.sup.3/g) Synthesis Example 30 104 89 0.86 0.007 1 Synthesis Example 150 520 190 0.37 0.130 2

Experimental Example 2

(21) X-ray diffraction analysis for the aluminosilicate particles according to Synthesis Examples 1 and 2 was carried out using an X-ray diffractometer (Bruker AXS D4-Endeavor XRD) under an applied voltage of 40 kV and an applied current of 40 mA. The results are shown in Table 2 below.

(22) The measured range of 26 was 10 to 90, and it was scanned at an interval of 0.05. Herein, a variable divergence slit of 6 mm was used as a slit, and a large PMMA holder (diameter=20 mm) was used to eliminate background noise due to the PMMA holder. Further, a full width at half maximum (FWHM) at a peak of about 29 which is the maximum peak in the 2 range of 20 to 37 was calculated in the data plot obtained by X-ray diffraction (XRD).

(23) TABLE-US-00002 TABLE 2 FWHM () I.sub.max () Crystal form Synthesis Example 1 6.745 29.2 amorphous Synthesis Example 2 FAU-type

(24) The aluminosilicate particles of Synthesis Example 2 had a FAU (faujasite) crystal structure, so the FWHM measurement was not performed.

Example 1

(25) 1.0 g of the amorphous aluminosilicate particles obtained in Synthesis Example 1 was added to 20 ml of mesitylene, and heated to 150 C. while stirring at 500 rpm. 0.08 g of bis(3-triethoxysilylpropyl)tetrasulfide (in 1.5 ml of mesitylene) was added thereto, and the mixture was stirred at 150 C. for 20 minutes.

(26) After completion of the stirring, solids were washed four times by centrifugation using toluene, and dried in an oven at 105 C. for 24 hours to obtain an organic-inorganic composite.

Example 2

(27) An organic-inorganic composite was obtained in the same manner as in Example 1, except that the amorphous aluminosilicate obtained in Synthesis Example 1 was pulverized to have a primary particle diameter of 20 nm or less.

Comparative Example 1

(28) An organic-inorganic composite was obtained in the same manner as in Example 1, except that the crystalline aluminosilicate particles obtained in Synthesis Example 2 were used instead of the amorphous aluminosilicate particles obtained in Synthesis Example 1.

Comparative Example 2

(29) An organic-inorganic composite was obtained in the same manner as in Example 1, except that kaolin clay (product name: Kaolin, manufactured by Sigma-Aldrich) was added instead of the amorphous aluminosilicate particles obtained in Synthesis Example 1.

Control Example

(30) An organic-inorganic composite was obtained in the same manner as in Example 1, except that silica particles (product name: 7000GR, manufactured by Evonik) was added instead of the amorphous aluminosilicate particles obtained in Synthesis Example 1.

Experimental Example 3

(31) The organic-inorganic composites according to Examples 1 and 2, Comparative Examples 1 and 2, and Control Example were subjected to thermogravimetric analysis using a thermogravimetric analyzer (STA 449 F3 Jupiter, NETZSCH) as follows.

(32) The base value is set by performing three times thermogravimetric analysis at a heating rate of 5 C./min in the range of 30 to 500 C. under an argon gas atmosphere. 10 to 20 mg of the above-mentioned organic-inorganic composite in a powder form was loaded into a special crucible and subjected to thermogravimetric analysis under the same experimental conditions.

(33) Derivative thermogravimetric curves converted from data obtained by the above analysis were obtained from the thermogravimetric analyzer, and are shown in FIG. 1 (Example 1), FIG. 2 (Example 2), FIG. 3 (Comparative Example 1), FIG. 4 (Comparative Example 2), and FIG. 5 (Control Example), respectively.

(34) The peak position ( C.) at which the silane coupling agent is desorbed from the organic-inorganic composite is shown in Table 3 below.

(35) Further, in the derivative thermogravimetric curve, an area (Da) of a region where an x-axis value is 300 to 500 C. and a y-axis value is zero (0) or more was obtained by the thermogravimetric analyzer and shown in Table 3 below.

(36) However, in the case of kaolin clay, weight loss due to hydroxyl groups on a particle surface occurs at 400 C. or higher. Therefore, the Da value for the organic-inorganic composite of Comparative Example 2 to which kaolin clay was applied was limited to a temperature range of 300 to 400 C.

(37) TABLE-US-00003 TABLE 3 Peak position (C.) Da Example 1 409.7 3.88 Example 2 413.1 4.21 Comparative Example 1 432.4 2.66 Comparative Example 2 372.4 2.47 Control Example 409.4 4.50

(38) Referring to Table 3, the organic-inorganic composites of Examples 1 and 2 had a Da value of 3.0 or more, and satisfied Equation 1.

(39) On the other hand, the organic-inorganic composites of Comparative Examples 1 and 2 had a Da value of less than 3.0, and thus did not satisfy Equation 1.

Preparation Example 1

(40) 737.24 g of a diene elastomer mixture (SSBR 2550, LG Chemical) and 375.32 g of the organic-inorganic composite according to Example 1 as a reinforcing material were added to a closed mixer. After mixing them at 150 C. for 5 minutes, 78.66 g of other additives (antioxidant, emulsifier, vulcanization accelerator, wax, etc.) were added thereto and mixed for 90 seconds.

(41) The resulting mixture was extruded in the form of a sheet having a thickness of 2 to 3 mm, and vulcanized at 160 C. to obtain a rubber molded product. At this time, the vulcanization time was controlled referring to data obtained by measuring the above mixture at 160 C. using a moving die rheometer (MDR).

Preparation Example 2

(42) A rubber molded product was obtained in the same manner as in Preparation Example 1, except that the organic-inorganic composite according to Example 2 was added as a reinforcing material.

Preparation Example 3

(43) A rubber molded product was obtained in the same manner as in Preparation Example 1, except that the organic-inorganic composite according to Comparative Example 1 was added as a reinforcing material.

Preparation Example 4

(44) A rubber molded product was obtained in the same manner as in Preparation Example 1, except that the organic-inorganic composite according to Comparative Example 2 was added as a reinforcing material.

Preparation Example 5

(45) A rubber molded product was obtained in the same manner as in Preparation Example 1, except that the organic-inorganic composite according to Control Example was added as a reinforcing material.

Experimental Example 4

(46) The relative volume loss index was measured according to DIN ISO 4649 using an abrasion tester (Bareiss GmbH) for the rubber molded products according to Preparation Examples 1 to 5.

(47) The relative volume loss index was calculated by the following equation for the rubber molded products of Preparation Examples 1 to 4, after determining the rubber molded product of Preparation Example 5 including the organic-inorganic composite of Control Example as a reference material.
The relative volume loss index={[(the relative volume loss of Preparation Example 5)(the relative volume loss of the corresponding Preparation Example)]/[the relative volume loss of Preparation Example 5)100]}+100

(48) TABLE-US-00004 TABLE 4 Relative volume loss index (%) Preparation Example 1 86 Preparation Example 2 89 Preparation Example 3 37 Preparation Example 4 24 Preparation Example 5 100

(49) Referring to Table 4, it was confirmed that the rubber molded products of Preparation Examples 1 and 2 to which the organic-inorganic composite of Example 1 or 2 was applied exhibited excellent abrasion resistance of twice or more as compared with the rubber molded products of Preparation Examples 3 and 4 to which the organic-inorganic composite of Comparative Example 1 or 2 was applied.