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Inorganic–organic hybrid pigment fabricated in the preparation process of organic pigment: Preparation and characterization
Dyes and Pigments 119 (2015) 75e83
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Dyes and Pigments journal homepage: www.elsevier.com/locate/dyepig
Inorganiceorganic hybrid pigment fabricated in the preparation process of organic pigment: Preparation and characterization Lingyun Cao a, Xuening Fei a, b, *, Hongbin Zhao b, Yingchun Gu b, * a b
School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China Colleges of Science, Tianjin Chengjian University, Tianjin 300384, China
a r t i c l e i n f o
a b s t r a c t
Article history: Received 1 January 2015 Received in revised form 6 March 2015 Accepted 9 March 2015 Available online 27 March 2015
Inorganiceorganic hybrid pigments were fabricated by adding inorganic mixture of precipitated white carbon black (SiO2) and TiO2 in preparation process of C.I. Pigment Yellow 13 and 83 composite with a mixed coupling method. Effects of mass ratio of inorganic/organic, SiO2/TiO2 and coupling component on the morphology and structure, color performance, thermal- and photo-stability of hybrid pigments were systematically investigated. It was found that the SiO2 was firstly encapsulated by organic pigment to form a coreeshell structure, and then combined with TiO2 through electrical adsorption. The morphology, particle size and distribution of hybrid pigments could be controlled by the mass ratio of inorganic/organic and SiO2/TiO2, and the color performance of hybrid pigments could be adjusted by the mass ratio of inorganic/organic and coupling component. Additionally, the hybrid pigment showed a better thermal- and photo-stability than organic pigment. © 2015 Elsevier Ltd. All rights reserved.
Keywords: Hybrid pigments White carbon black TiO2 Mixed coupling method Preparation Characterization
1. Introduction Inorganiceorganic hybrids have attracted wide attention because they have the advantages of both organic and inorganic materials [1], and hybrid materials with extraordinary new properties and multifunctional character not only represent a new field of basic research, but also provide prospects for many new applications in various areas, such as optics, solid electrolytes, catalysis, biomaterials and biomedical applications [2e4]. Similarly, preparation of inorganiceorganic hybrid pigments is always used as a strategy to solve the problems of organic pigments in applications, such as poor dispersion ability, low weather durability, poor thermal- and photo-stability [5]. There are three ways to prepare hybrid pigments, encapsulation of organic pigment with inorganic materials [6e10], adsorption of dyes onto inorganic materials [11e14] and inorganic core modification [15e18]. Generally, the encapsulation of organic pigment with inorganic materials is realized through layerby-layer assembly technique, solegel method and hydrolysis reaction. Yuan et al. [6,8] encapsulated nano silica and titania onto the surface of C.I. Pigment Yellow 109 using a layer-by-layer assembly
* Corresponding authors. Tianjin Chengjian University, No. 26 Jinjing Road, Xiqing District, Tianjin, China. Tel.: þ86 22 23773360; fax: þ86 22 23085032. E-mail addresses: [email protected] (X. Fei), [email protected] (Y. Gu). http://dx.doi.org/10.1016/j.dyepig.2015.03.020 0143-7208/© 2015 Elsevier Ltd. All rights reserved.
technique and solegel method with the help of polyelectrolyte, and the encapsulation improved the thermal stability, wettability, acid and alkali resistance, and weather ability of organic pigment. Wen et al. [9] coated C. I. Pigment Yellow 13 (PY13) with SiO2 via the hydrolysis of Na2SiO3 on the surface of organic pigment. Adsorption of organic dyes onto inorganic materials to prepare hybrid pigments is always carried out with the help of coupling reagent and the inherent pore structure of inorganic material. For example, Jesionowski et al. [19,20] prepared a series of hybrid pigment by adsorption basic dyes and acidic dyes on the surface of silica supports modified with silane coupling agent. Tang et al. [12,21] fabricated yellow pigments with excellent thermo- and photostability by the intercalation C.I. Mordant Yellow 3 (MY3) anions and C.I. Mordant Yellow 10 (HSAB) to ZneAl layered double hydroxides (LDHs). Compared with two mentioned ways to prepare hybrid pigment, the inorganic core modification is simpler. It can be carried out by a simple post-processing method and in the preparation process of organic pigment. Hayashi et al. [16,17] prepared a nanosized coreeshell pigment by dry milling of organic pigments together with nano-sized and surface-modified silica powder. Our group successfully prepared hybrid pigment with a coreeshell in the preparation process of organic pigment, and the hybrid pigment showed better thermal- and photo-stability than the original organic pigment [15,18]. Up to now, however, there has
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been no report involved in the properties of hybrid pigment using the inorganic part as the main component. And the study on the morphology and properties changing with the inorganic/organic ratio is significant, which is benefit for the maximum improvement in the properties of organic pigment. Herein, we prepared an inorganiceorganic hybrid yellow pigment in the preparation process of organic pigment using precipitated white carbon black (SiO2) and TiO2 as inorganic substrate, and the inorganic/organic and SiO2/TiO2 mass ratio ranged from 1/1 to 4/1 and 1/3 to 3/1 respectively. Effects of mass ratio of inorganic/organic and SiO2/TiO2 on the morphology and properties of hybrid pigment were investigated, and the hybrid pigments were characterized by transmission electron microscopy (TEM), fourier transform-infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and UVevis spectra respectively. 2. Experiment section
combined with thermogravimetric analysis (TGA), and the UVeVis spectra between 200 and 800 nm of the prepared hybrid pigments were obtained with a Lambda 35 spectrometer in the diffuse reflectance mode in a powder state. 2.2.3. Color performance of the prepared hybrid pigments The color performance of the prepared hybrid pigments were tested and compared, and the color parameters were determined by coupling analytical software to spectrophotometer. The Commission Internationale de l'Eclairage (CIE) 1976 L*a*b* and L*c*H colorimetric method was used, as recommended by the CIE. The data were registered from 380 to 780 nm using BaSO4 as the standard, D65 standard illuminant, 10 complementary observer, and measuring geometry d/8 . The obtained color parameters L*, a*, b*, c* and H were used to evaluate the lightness, green hue, yellow hue, yellow purification, and hue angle of prepared hybrid pigments. In addition, the color strength of prepared hybrid pigment was tested using PY13 as standard.
2.1. Materials Sulphonated castor oil, precipitated white carbon black (SiO2, specific surface area: 167.227 m2/g, pore volume: 1.670 cm3/g), TiO2 and PY13, 3,30 -dichlorobenzidine dihydrochloride (DCB), 20 ,40 dimethylaceto-acetanilide (AAMX) and 40 -chloro-20 ,50 -dimethoxyaceto-acetanilide (IRG) were obtained commercially. The other reagents NaOH, HCl, CH3COOH, NaNO2 and methylbenzene were analytical reagents. 2.2. Methods 2.2.1. Preparation of hybrid pigments Firstly, the coupling component was prepared by the following procedure: Under magnetic stirring, NaOH (2.50 g) was dissolved in 50 mL water and heated to 30 C to obtain an alkaline solution, then the AAMX and IRG (AAMX þ IRG ¼ 5.10 g) were added to achieve a light color solution without obvious insoluble substance. Then, the solution was poured into a four-neck round-bottom flask and mixed with SiO2, TiO2, sulphonated castor oil (1.50 g) and methylbenzene (3e6 drops) with the help of mechanical agitation at room temperature. After 30 min, 6 mL CH3COOH was added. Next, the diazonium salt solution was prepared. DCB (3.0 g) was dissolved in a solution of water (40 mL) and HCl (37%, 2.6 mL), and then the mixture was cooled and kept at 0e5 C. A NaNO2 (1.36 g) aqueous solution with a concentration of 30% (w/w) was dropwise added to the mixture within 1e2 min to obtain a light yellow solution. Finally, the inorganiceorganic hybrid pigment was prepared. The diazonium salt solution was turned into a pressure-equalizing funnel and dropwise added to couple with the coupling component within 20e30 min, and the mixed coupling equation was illustrated in Scheme 1. After continuous reaction for another 30 min, the mixed solution was heated and kept at 70e80 C for 40 min and 100 C for 1 h. Then, the mixture was filtered, washed to neutral, dried at 60 C and grinded to obtain the inorganiceorganic hybrid pigment. The inorganiceorganic hybrid pigments with different mass ratio of inorganic/organic, SiO2/TiO2 and AAMX/IRG were listed in Table 1. 2.2.2. Characterization of prepared hybrid pigments The structure of pigment samples were determined by fourier trans-form-infrared spectroscopy (FT-IR, Nicolet 380, Thermo Electron Corporation, USA) and transmission electron microscopy (TEM, JEM-2100, NEC Corporation, Japan), and the crystalline forms of pigments were measured by X-ray diffraction (XRD, BDX330, Peking University Instrument Factory, China). The heat resistance of pigment was analyzed by differential thermal analysis (DTA)
2.2.4. Heat and light resistance of prepared hybrid pigment The heat resistance of the prepared hybrid pigments was tested and compared with PY13 by the procedure as follows: 2.5 g pigments was placed in a crucible and heated in an oven at 140, 160, 180, 200, 220 and 250 C for 30 min, and then the DE values of the pigments were recorded after each heating step. The light resistance of hybrid pigment was evaluated by a UV accelerated aging experiment. The sample was prepared by mixing the glass bead (80 g), acrylic resin (20 g), water (20 g), defoamer (0.05 g) and hybrid pigment (10 g) with a high-speed rail concussion instrument (GD-425, China), and painted on the white board. Then the white board was photoaged under the UV irradiation with a 250 W high pressure mercury lamp, and the color change (DE) value was recorded every 10 min during 1 h irradiation. 3. Results and discussion 3.1. Preparation process of hybrid pigments 3.1.1. Effects of inorganic/organic mass ratio on the morphology Fig. 1 illustrated the TEM analysis results of hybrid pigment with different mass ratio of inorganic/organic. It could be found that the morphology, particle size and distribution of prepared hybrid pigments changed obviously with the mass ratio of inorganic/organic. With the increase in inorganic mass fraction, the hybrid pigments turned from irregularly shaped (Fig. 1a and b) to almost round shaped (Fig. 1c and d). In addition, the particle size of prepared hybrid pigments gradually decreased when the inorganic/organic mass ratio increased from 1/1 to 4/1, and their particle size distribution became more and more uniform. From what stated above, it could be concluded that the morphology, particle size and distribution of prepared pigments could be controlled by the mass ratio of inorganic/organic. In addition, as shown in Fig. 1e, the particle size of SiO2 was approximately 30e50 nm, and Fig. 1f illustrated that the SiO2 was encapsulate by organic pigment composite to form a coreeshell structure. 3.1.2. Effects of SiO2/TiO2 mass ratio on the morphology The morphology of hybrid pigments with different mass ratio of SiO2/TiO2 was observed by TEM, and the results were shown in Fig. 2. As shown in Fig. 2d, the particles with large size had a lattice spacing of ca. 0.32 nm corresponded to the (110) planes of rutile TiO2, suggesting that the particles with a large particle size of 200e300 nm in prepared hybrid pigments were TiO2. From Fig. 2aec, it could be found that the SiO2/organic pigment composites were combined on the surface of TiO2, and their
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Scheme 1. Mixed coupling equation for the preparation of organic pigment composite.
combination style changed with the increase in SiO2/TiO2 mass ratio. In the hybrid pigment with low SiO2/TiO2 mass ratio, the TiO2 particles were fully coated by the SiO2/organic pigment composite. However, in the hybrid pigment with high SiO2/TiO2 mass ratio, the SiO2/organic pigment composite was covered by the TiO2 particles. 3.1.3. Effects of inorganic/organic and SiO2/TiO2 on color performance The color performance of prepared hybrid pigment with different mass ratio of inorganic/organic and SiO2/TiO2 were tested and compared, and the results were shown in Table 2. As mentioned above, the hybrid with SiO2/TiO2 could reduce the particle size of organic pigment, which was responsible for the higher color strength of Hybrid-1/1 and Hybrid-2/1. However, with continuous increase in the mass ratio of inorganic/organic, the TiO2 mass fraction in hybrid pigment also increased, which resulted in the low color strength of hybrid pigments with higher mass ratio of inorganic/organic and SiO2/TiO2. Also, it could be found that the L* value for hybrid pigments gradually increased with the TiO2 mass fraction, and it was even higher than that for PY13 when the TiO2 mass fraction was over 25% (Hybrid-3/1), suggesting that the hybrid pigments with higher TiO2 mass fraction showed more light. However, these hybrid pigments showed too green hue and lower yell purity than the organic pigment, which was expressed by the lower value of color coordinate a* and c*, respectively. Table 1 Samples of prepared hybrid pigments. Sample
Inorganica/organicb
SiO2/TiO2
AAMX/IRG
Hybrid-1/1 Hybrid-2/1 Hybrid-3/1 Hybrid-4/1c Hybrid-Si1/Ti1 Hybrid-Si1/Ti3 Hybrid-Si3 PY13(70)/PY83(30) PY13(60)/PY83(40) PY13(50)/PY83(50)
1:1 2:1 3:1 4:1 4:1 4:1 3:1 4:1 4:1 4:1
3:1 3:1 3:1 3:1 1:1 1:3 Without TiO2 3:1 3:1 3:1
80:20 80:20 80:20 80:20 80:20 80:20 80:20 70:30 60:40 50:50
a b c
SiO2 and TiO2 mixture. PY13 and 83 composite. Hybrid-Si3/Ti1.
3.1.4. Effects of AAMX/IRG mass ratio on color performance As the coupling component for PY13 and PY83 respectively, the AAMX and IRG had different groups on the benzene ring, which affected the color performance of organic pigments. Thus, the mass ratio of AAMX/IRG affected the color performance of prepared hybrid pigments as shown in Table 3. Obviously, due to the inherent stronger color strength of PY83 than PY13, the color strength of hybrid pigments with higher IRG mass fraction showed higher color strength. Additionally, the hybrid pigment with higher IRG mass fraction had a higher value in Chrome (c*), suggesting a more pure yellow hue. When the IRG/ AAMX increased from 20/80 to 50/50, the hybrid pigments showed an increase in red and yellow hue, which was expressed by the increase in the value of the color coordinate a* and b* respectively. For the hue angle of hybrid pigment, although it decreased with the increase in IRG/AAMX mass ratio, it was still higher than that of PY13 and lied in the yellow region of cylindrical color space (H ¼ 75e105 for yellow) [22]. 3.2. Characterization of hybrid pigment 3.2.1. FT-IR analysis of the samples The proof of the composite nature of the prepared hybrid pigments was provided by FT-IR analysis, and the results were shown Fig. 3. As illustrated in Fig. 3a, the spectra of hybrid pigments with different mass ratio of inorganic/organic were similar, and the characteristic peaks at 1510 cm1 and 1672 cm1 belonged to C]O stretching vibration absorption peak of eCONHe group and the CeC frame vibration absorption peak of phenyl ring in PY13 and PY83. In the spectra of SiO2, the characteristic peaks at 806 cm1 and 1100 cm1 corresponded to SieOeSi stretching vibration absorption peak and SieO asymmetric absorption peak. By comparison, it could be seen that in the spectra of prepared hybrid pigments the characteristic peaks of SiO2 was gradually weakened with the increase in the mass fraction of organic pigment, suggesting an encapsulation of SiO2 by organic pigment. Fig. 3b showed the spectra of TiO2 and hybrid pigments with different mass ratio of SiO2/TiO2. It could be found that the characteristic peak at 690 cm-1 corresponded to the TieOeTi stretching vibration absorption peak was only observed in a high mass
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Fig. 1. TEM patterns of Hybrid-1/1 (a), 2/1 (b), 3/1 (c), 4/1 (d), SiO2 (e) and Hybrid-Si3 (f).
fraction of TiO2, which was suggested that the high mass fraction of TiO2 deposited on the surface of SiO2/organic pigment composite, however, the low mass fraction of TiO2 was covered by the SiO2/ organic pigment composite. 3.2.2. XRD analysis of the samples The XRD analysis results of the prepared hybrid pigments with different mass ratio of inorganic/organic and SiO2/TiO2 were shown in Fig. 4. As shown in Fig. 4a, in the curve of Hybrid-4/1, the diffraction peaks of the organic pigments (2q ¼ 10.97, 17.16 , 25.73 and 27.02 ) disappeared, only a slight wide diffraction peak of SiO2 and strong diffraction peaks of TiO2 were observed. However, with the increase in the mass ration of organic/inorganic from 1:4 to 1:1, with the gradual disappearance of the diffraction peaks of SiO2
(2q ¼ 22.01 ), the diffraction peaks of organic pigments began to be observed as shown in Fig. 4b. Fig. 4c showed the analysis results of the hybrid pigments with a fixed mass ratio of inorganic/organic at 4:1 and different mass of TiO2/SiO2, it could be found that when the mass ratio of TiO2/SiO2 increased from 1:3 to 3:1, the intensity of diffraction peaks for TiO2 in the hybrid pigments gradually enhanced. In the preparation process, the SiO2 with good pore structure as shown in Fig. 4d could effectively adsorb the coupling component to its surface and pore channel, and then organic pigments was synthesized in its pore channel and on its surface when the diazonium salt was added. Thus, in a low mass ratio of organic/inorganic (Hybrid-4/1), most of organic pigment embedded in the pore channel of SiO2, and their diffraction peaks were covered by SiO2 [7]. But in a high mass ratio of organic/inorganic (Hybrid-1/1), the
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Fig. 2. TEM patterns of hybrid-Si3/Ti1 (a), Si1/Ti1 (b) and Si1/Ti3 (c) and TiO2 lattice structure (d).
organic pigment encapsulated SiO2 and covered their diffraction peaks [18]. For the TiO2 with poor pore structure, under the pH value of the reaction mixture (pH ¼ 3e4), it showed positive charged. However, the organic pigment adsorbed the anion surfactant sulphonated castor and showed negative charged [23]. Thus, the SiO2/organic pigment composite combined with TiO2 through electrical adsorption, which was the reason for the change of the intensity of diffraction peaks for TiO2 with the mass ratio of TiO2/SiO2. Based on preceding description, the proposed mechanism for the encapsulation of SiO2 by organic pigment and the combination of SiO2/organic pigment composite with TiO2 could be described schematically as shown in Scheme 2.
3.2.3. Thermal stability of the hybrid pigments The thermal stabilities of the hybrid pigments with different mass ratio of inorganic/organic and SiO2/TiO2 were tested and compared, and the results were shown in Fig. 5. As shown in Fig. 5a, the prepared hybrid pigments did not show weight loss until the temperature reached up to about 310 C, suggesting an excellent thermal stability. In addition, with the increase in the mass ratio of the inorganic/organic, the thermal stability of the hybrid pigment was gradually improved. In a high mass ratio of the inorganic/organic, the main component of the hybrid pigments was inorganic materials and they showed more characteristic of SiO2 and TiO2, which resulted in a better thermal stability. Fig. 5b showed that a higher mass ratio of TiO2/SiO2 resulted in a better thermal stability of the prepared hybrid pigments. As mentioned above, the TiO2 combined with SiO2/organic pigment composite through electrical adsorption. Therefore, in a high mass ratio of TiO2/SiO2, the TiO2 deposited on the surface of prepared
Table 2 Color coordinates of hybrid pigments with different mass ratio of inorganic/organic and SiO2/TiO2. Sample
PY13 Hybrid-1/1 Hybrid-2/1 Hybrid-3/1 Hybrid-4/1 Hybrid-Si3/Ti1 Hybrid-Si1/Ti1 Hybrid-Si1/Ti3 a
Color coordinates
Color strength (%)a
L*
a*
b*
c*
H
78.17 76.32 77.31 78.68 79.05
10.27 11.47 10.44 6.34 4.08
81.19 80.23 81.44 79.82 75.73
81.83 81.16 82.06 79.93 75.64
82.79 81.63 83.87 86.91 88.44
e 121.96 113.64 98.20 81.62
79.09 79.27
3.85 3.71
73.88 68.22
73.78 68.13
88.43 87.85
72.79 51.68
Using PY13 as standard.
Table 3 Color performance of hybrid pigments with different mass ratio of AAMX/IRG. Hybrid pigmentsa
PY13(80)/PY83(20) PY13(70)/PY83(30) PY13(60)/PY83(40) PY13(50)/PY83(50) a b
Color coordinates L
a*
b*
c*
H
79.05 79.26 78.19 77.63
4.08 7.03 9.55 10.77
75.73 78.92 79.10 79.50
75.64 78.56 78.95 79.57
88.44 86.60 84.12 83.27
Inorganic/organic ¼ 4:1 and SiO2/TiO2 ¼ 3:1. Using PY13 as standard.
Color strength (%)b 81.62 84.61 88.22 94.69
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Fig. 3. FT-IR analysis results of the hybrid pigments with different mass ratio of inorganic/organic (a) and SiO2/TiO2 (b).
hybrid pigment, which effectively improve the thermal stability of hybrid pigments [7]. 3.2.4. UVevis spectra of the hybrid pigments The UVevis diffuse-reflectance spectra of organic pigments and prepared hybrid pigments were presented in Fig. 6. Because the spectra were determined in the powder state and diffuse-reflectance mode, they helped to determine the absorbing and scattering properties of the pigments. The lower the diffusereflectance absorbance was, the higher the scattering property of the pigment was [7]. As shown in Fig. 6a, the intensity of the absorbance peaks in the UV region and visible region of 400e550 nm for the prepared hybrid pigments were lower than that for the organic pigment, indicating that the hybrid with the SiO2 and TiO2 obviously improved the photo-stability of organic pigment. Moreover, it could be found that the intensity of the absorbance peaks in 200e400 nm was gradually increased when the mass ratio of inorganic/organic increased from 1:1 to 4:1. With the increase of mass ration of inorganic/organic, the mass fraction
of TiO2 increased, which resulted in higher absorbance intensity in the UV region since the TiO2 had an obvious UV absorbance band especially under 270 nm [7]. Thus, it protected the organic pigment from UV light and caused a higher UV shielding property of hybrid pigments. Fig. 6b showed the UVevis spectra of the hybrid pigments with different mass ratio of SiO2/TiO2. It was found that the adsorption intensity of the hybrid pigments in the UV region was similar, but adsorption intensity in the wavelength of 400e550 nm decreased obviously when the mass ratio of SiO2/TiO2 decreased from 3:1 to 1:1. The higher mass fraction of TiO2 was, the more TiO2 deposited on the surface of the hybrid pigments, causing higher light scattering properties of the hybrid pigments in the visible region since the rutile TiO2 have good reflection properties in the visible to nearinfrared region [24]. 3.2.5. Heat and light resistance of prepared hybrid pigments The color change of prepared hybrid pigments, taking PY13(60)/ PY83(40) for example, after heat treatment under powder state and
Fig. 4. XRD analysis results of the prepared hybrid pigments and the pore structure of SiO2 and TiO2.
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Scheme 2. Mechanism for the preparation of hybrid pigment.
UV accelerated aging treatment of the thin film painted with prepared acrylic resin watery ink were tested and compared with PY13, and the results were shown in Fig. 7. As shown in Fig. 7a, it could be found that the DE value for hybrid pigment PY13(60)/PY83(40) was 2.39 after heating at 250 C for 30 min, which was lower than that for the PY13, suggesting that the prepared hybrid pigment possessed better heat resistance property. And as shown in Fig. 7b, after 1 h UV irradiation, the DE value of the watery ink prepared with Hybrid-PY13(60)/PY83(40) was only 0.45, which was also lower than that for the PY13,
indicating that the prepared hybrid pigment had good light resistance property due to the excellent UV shield property of SiO2 and TiO2, which was consistent with the UVevis spectra analysis results. 4. Conclusion A series of inorganiceorganic hybrid pigments were fabricated by adding inorganic mixture of SiO2 and TiO2 in preparation process of PY13 and 83 composite with a mixed coupling method. The
Fig. 5. Thermal analysis of the hybrid pigments with different mass ratio of inorganic/organic (a) and SiO2/TiO2 (b).
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Fig. 6. UVevis diffuse-reflectance spectra of the prepared hybrid pigments with different mass ratio of inorganic/organic (a) and SiO2/TiO2 (b).
Fig. 7. Heat (a) and light (b) resistance of hybrid pigment PY13(60)/PY83(40) and PY13.
inorganic/organic, SiO2/TiO2 and coupling component mass ratios could control the morphology, particle size and distribution and color performance of prepared hybrid pigments. The characterization results showed that the SiO2 was firstly encapsulated by organic pigment to form a coreeshell structure, and then combined with TiO2 through electrical adsorption. The thermal and UVevis spectra analysis results showed that the hybrid pigment showed a better thermal- and photo-stability than organic pigment. And the DE value for hybrid pigment PY13(60)/PY83(40) heated at 250 C for 30 min and irradiated under 250 W UV lamp were 2.39 and 0.45 respectively, which was lower than that for the PY13, suggesting that the prepared hybrid pigment possessed better properties of heat and light resistance than the organic pigment.
Acknowledgment This work has been partly supported by the National Natural Science Foundation of China (51178289).
References [1] Pardo R, Zayat M, Levy D. Photochromic organiceinorganic hybrid materials. Chem Soc Rev 2011;40:672e87. [2] Chen S, Sui JJ, Chen L. Positional assembly of hybrid polyurethane nanocomposites via incorporation of inorganic building blocks into organic polymer. Colloid Polym Sci 2004;283:66e73. [3] Petrovic ZS, Javni I, Waddon A, Banhegyi G. Structure and properties of polyurethane-silica nanocomposites. J Appl Polym Sci 2000;76:133e51.
[4] Sanchez C, Belleville P, Popall M, Nicole L. Applications of advanced hybrid organiceinorganic nanomaterials: from laboratory to market. Chem Soc Rev 2011;40:696e753. [5] Herbst W, Hunger K. Industrial organic pigments: production, properties, applications. 3rd ed. Weinheim: Wiley-VCH; 2006. [6] Yuan J, Xing W, Gu G, Wu L. The properties of organic pigment encapsulated with nano-silica via layer-by-layer assembly technique. Dyes Pigm 2008;76: 463e9. [7] Yuan J, Zhou S, Wu L, You B. Organic pigment particles coated with titania via solegel process. J Phys Chem B 2006;110:388e94. [8] Yuan J, Zhou S, You B, Wu L. Organic pigment particles coated with colloidal nano-silica particles via layer-by-layer assembly. Chem Mater 2005;17: 3587e94. [9] Wen Z, Feng Y, Li X, Bai Y, Tang Q, Gao Y. Fabrication of diarylide yellow pigments/modified SiO2 coreeshell hybrid composite particles for electrophoretic displays. Curr Appl Phys 2012;12:259e65. Fabjan, Skapin [10] ES AS, Skrlep L, Zivec P, Ceh M, Gabers cek M. Protection of organic pigments against photocatalysis by encapsulation. J Sol Gel Sci Technol 2012;62:65e74. [11] Tang P, Feng Y, Li D. Facile synthesis of multicolor organiceinorganic hybrid pigments based on layered double hydroxides. Dyes Pigm 2014;104:131e6. [12] Tang P, Deng F, Feng Y, Li D. Mordant yellow 3 anions intercalated layered double hydroxides: preparation, thermo-and photostability. Ind Eng Chem Res 2012;51:10542e5. [13] Jesionowski T, Przybylska A, Kurc B, Ciesielczyk F. Hybrid pigments preparation via adsorption of C.I. Mordant Red 3 on both unmodified and aminosilane-functionalised silica supports. Dyes Pigm 2011;89:127e36. [14] Jesionowski T, Binkowski S, Krysztafkiewicz A. Adsorption of the selected organic dyes on the functionalized surface of precipitated silica via emulsion route. Dyes Pigm 2005;65:267e79. [15] Fei X, Zhang T, Zhou C. Modification study involving a naphthol as red pigment. Dyes Pigm 2000;44:75e80. [16] Horiuchi S, Horie S, Ichimura K. Coreeshell structures of silicaeorganic pigment nanohybrids visualized by electron spectroscopic imaging. ACS Appl Mater Interfaces 2009;1:977e81. [17] Hayashi K, Morii H, Iwasaki K, Horie S, Horiishi N, Ichimura K. Uniformed nano-downsizing of organic pigments through coreeshell structuring. J Mater Chem 2007;17:527e30.
L. Cao et al. / Dyes and Pigments 119 (2015) 75e83 [18] Cao L, Fei X, Zhang T, Yu L, Gu Y, Zhang B. Modification of C.I. Pigment Red 21 with sepiolite and lithopone in its preparation process. Ind Eng Chem Res 2014;53:31e7. [19] Jesionowski T, Nowacka M, Ciesielczyk F. Electrokinetic properties of hybrid pigments obtained via adsorption of organic dyes on the silica support. Pigm Resin Technol 2012;41:9e19. [20] Jesionowski T, Pokora M, Tylus W, Dec A, Krysztafkiewicz A. Effect of N-2(aminoethyl)-3-aminopropyltrimethoxysilane surface modification and C.I. Acid Red 18 dye adsorption on the physicochemical properties of silica precipitated in an emulsion route, used as a pigment and a filler in acrylic paints. Dyes Pigm 2003;57:29e41.
83
[21] Tang P, Xu X, Lin Y, Li D. Enhancement of the thermo-and photostability of an anionic dye by intercalation in a zinc-aluminum layered double hydroxide host. Ind Eng Chem Res 2008;47:2478e83. P, Trojan M. Thermal synthesis of the (Bi2O3)1x (Er2O3)x pigments. [22] Sulcov a J Therm Anal Calorim 2007;88:111e3. [23] Sis H, Birinci M. Adsorption characteristics of ionic and nonionic surfactants on hydrophobic pigment in aqueous medium. Color Technol 2012;128:244e9. [24] Bendiganavale AK, Malshe VC. Infrared reflective inorganic pigments. Recent Pat Chem Eng 2008;1:67e79.
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Dyes and Pigments journal homepage: www.elsevier.com/locate/dyepig
Inorganiceorganic hybrid pigment fabricated in the preparation process of organic pigment: Preparation and characterization Lingyun Cao a, Xuening Fei a, b, *, Hongbin Zhao b, Yingchun Gu b, * a b
School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China Colleges of Science, Tianjin Chengjian University, Tianjin 300384, China
a r t i c l e i n f o
a b s t r a c t
Article history: Received 1 January 2015 Received in revised form 6 March 2015 Accepted 9 March 2015 Available online 27 March 2015
Inorganiceorganic hybrid pigments were fabricated by adding inorganic mixture of precipitated white carbon black (SiO2) and TiO2 in preparation process of C.I. Pigment Yellow 13 and 83 composite with a mixed coupling method. Effects of mass ratio of inorganic/organic, SiO2/TiO2 and coupling component on the morphology and structure, color performance, thermal- and photo-stability of hybrid pigments were systematically investigated. It was found that the SiO2 was firstly encapsulated by organic pigment to form a coreeshell structure, and then combined with TiO2 through electrical adsorption. The morphology, particle size and distribution of hybrid pigments could be controlled by the mass ratio of inorganic/organic and SiO2/TiO2, and the color performance of hybrid pigments could be adjusted by the mass ratio of inorganic/organic and coupling component. Additionally, the hybrid pigment showed a better thermal- and photo-stability than organic pigment. © 2015 Elsevier Ltd. All rights reserved.
Keywords: Hybrid pigments White carbon black TiO2 Mixed coupling method Preparation Characterization
1. Introduction Inorganiceorganic hybrids have attracted wide attention because they have the advantages of both organic and inorganic materials [1], and hybrid materials with extraordinary new properties and multifunctional character not only represent a new field of basic research, but also provide prospects for many new applications in various areas, such as optics, solid electrolytes, catalysis, biomaterials and biomedical applications [2e4]. Similarly, preparation of inorganiceorganic hybrid pigments is always used as a strategy to solve the problems of organic pigments in applications, such as poor dispersion ability, low weather durability, poor thermal- and photo-stability [5]. There are three ways to prepare hybrid pigments, encapsulation of organic pigment with inorganic materials [6e10], adsorption of dyes onto inorganic materials [11e14] and inorganic core modification [15e18]. Generally, the encapsulation of organic pigment with inorganic materials is realized through layerby-layer assembly technique, solegel method and hydrolysis reaction. Yuan et al. [6,8] encapsulated nano silica and titania onto the surface of C.I. Pigment Yellow 109 using a layer-by-layer assembly
* Corresponding authors. Tianjin Chengjian University, No. 26 Jinjing Road, Xiqing District, Tianjin, China. Tel.: þ86 22 23773360; fax: þ86 22 23085032. E-mail addresses: [email protected] (X. Fei), [email protected] (Y. Gu). http://dx.doi.org/10.1016/j.dyepig.2015.03.020 0143-7208/© 2015 Elsevier Ltd. All rights reserved.
technique and solegel method with the help of polyelectrolyte, and the encapsulation improved the thermal stability, wettability, acid and alkali resistance, and weather ability of organic pigment. Wen et al. [9] coated C. I. Pigment Yellow 13 (PY13) with SiO2 via the hydrolysis of Na2SiO3 on the surface of organic pigment. Adsorption of organic dyes onto inorganic materials to prepare hybrid pigments is always carried out with the help of coupling reagent and the inherent pore structure of inorganic material. For example, Jesionowski et al. [19,20] prepared a series of hybrid pigment by adsorption basic dyes and acidic dyes on the surface of silica supports modified with silane coupling agent. Tang et al. [12,21] fabricated yellow pigments with excellent thermo- and photostability by the intercalation C.I. Mordant Yellow 3 (MY3) anions and C.I. Mordant Yellow 10 (HSAB) to ZneAl layered double hydroxides (LDHs). Compared with two mentioned ways to prepare hybrid pigment, the inorganic core modification is simpler. It can be carried out by a simple post-processing method and in the preparation process of organic pigment. Hayashi et al. [16,17] prepared a nanosized coreeshell pigment by dry milling of organic pigments together with nano-sized and surface-modified silica powder. Our group successfully prepared hybrid pigment with a coreeshell in the preparation process of organic pigment, and the hybrid pigment showed better thermal- and photo-stability than the original organic pigment [15,18]. Up to now, however, there has
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been no report involved in the properties of hybrid pigment using the inorganic part as the main component. And the study on the morphology and properties changing with the inorganic/organic ratio is significant, which is benefit for the maximum improvement in the properties of organic pigment. Herein, we prepared an inorganiceorganic hybrid yellow pigment in the preparation process of organic pigment using precipitated white carbon black (SiO2) and TiO2 as inorganic substrate, and the inorganic/organic and SiO2/TiO2 mass ratio ranged from 1/1 to 4/1 and 1/3 to 3/1 respectively. Effects of mass ratio of inorganic/organic and SiO2/TiO2 on the morphology and properties of hybrid pigment were investigated, and the hybrid pigments were characterized by transmission electron microscopy (TEM), fourier transform-infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and UVevis spectra respectively. 2. Experiment section
combined with thermogravimetric analysis (TGA), and the UVeVis spectra between 200 and 800 nm of the prepared hybrid pigments were obtained with a Lambda 35 spectrometer in the diffuse reflectance mode in a powder state. 2.2.3. Color performance of the prepared hybrid pigments The color performance of the prepared hybrid pigments were tested and compared, and the color parameters were determined by coupling analytical software to spectrophotometer. The Commission Internationale de l'Eclairage (CIE) 1976 L*a*b* and L*c*H colorimetric method was used, as recommended by the CIE. The data were registered from 380 to 780 nm using BaSO4 as the standard, D65 standard illuminant, 10 complementary observer, and measuring geometry d/8 . The obtained color parameters L*, a*, b*, c* and H were used to evaluate the lightness, green hue, yellow hue, yellow purification, and hue angle of prepared hybrid pigments. In addition, the color strength of prepared hybrid pigment was tested using PY13 as standard.
2.1. Materials Sulphonated castor oil, precipitated white carbon black (SiO2, specific surface area: 167.227 m2/g, pore volume: 1.670 cm3/g), TiO2 and PY13, 3,30 -dichlorobenzidine dihydrochloride (DCB), 20 ,40 dimethylaceto-acetanilide (AAMX) and 40 -chloro-20 ,50 -dimethoxyaceto-acetanilide (IRG) were obtained commercially. The other reagents NaOH, HCl, CH3COOH, NaNO2 and methylbenzene were analytical reagents. 2.2. Methods 2.2.1. Preparation of hybrid pigments Firstly, the coupling component was prepared by the following procedure: Under magnetic stirring, NaOH (2.50 g) was dissolved in 50 mL water and heated to 30 C to obtain an alkaline solution, then the AAMX and IRG (AAMX þ IRG ¼ 5.10 g) were added to achieve a light color solution without obvious insoluble substance. Then, the solution was poured into a four-neck round-bottom flask and mixed with SiO2, TiO2, sulphonated castor oil (1.50 g) and methylbenzene (3e6 drops) with the help of mechanical agitation at room temperature. After 30 min, 6 mL CH3COOH was added. Next, the diazonium salt solution was prepared. DCB (3.0 g) was dissolved in a solution of water (40 mL) and HCl (37%, 2.6 mL), and then the mixture was cooled and kept at 0e5 C. A NaNO2 (1.36 g) aqueous solution with a concentration of 30% (w/w) was dropwise added to the mixture within 1e2 min to obtain a light yellow solution. Finally, the inorganiceorganic hybrid pigment was prepared. The diazonium salt solution was turned into a pressure-equalizing funnel and dropwise added to couple with the coupling component within 20e30 min, and the mixed coupling equation was illustrated in Scheme 1. After continuous reaction for another 30 min, the mixed solution was heated and kept at 70e80 C for 40 min and 100 C for 1 h. Then, the mixture was filtered, washed to neutral, dried at 60 C and grinded to obtain the inorganiceorganic hybrid pigment. The inorganiceorganic hybrid pigments with different mass ratio of inorganic/organic, SiO2/TiO2 and AAMX/IRG were listed in Table 1. 2.2.2. Characterization of prepared hybrid pigments The structure of pigment samples were determined by fourier trans-form-infrared spectroscopy (FT-IR, Nicolet 380, Thermo Electron Corporation, USA) and transmission electron microscopy (TEM, JEM-2100, NEC Corporation, Japan), and the crystalline forms of pigments were measured by X-ray diffraction (XRD, BDX330, Peking University Instrument Factory, China). The heat resistance of pigment was analyzed by differential thermal analysis (DTA)
2.2.4. Heat and light resistance of prepared hybrid pigment The heat resistance of the prepared hybrid pigments was tested and compared with PY13 by the procedure as follows: 2.5 g pigments was placed in a crucible and heated in an oven at 140, 160, 180, 200, 220 and 250 C for 30 min, and then the DE values of the pigments were recorded after each heating step. The light resistance of hybrid pigment was evaluated by a UV accelerated aging experiment. The sample was prepared by mixing the glass bead (80 g), acrylic resin (20 g), water (20 g), defoamer (0.05 g) and hybrid pigment (10 g) with a high-speed rail concussion instrument (GD-425, China), and painted on the white board. Then the white board was photoaged under the UV irradiation with a 250 W high pressure mercury lamp, and the color change (DE) value was recorded every 10 min during 1 h irradiation. 3. Results and discussion 3.1. Preparation process of hybrid pigments 3.1.1. Effects of inorganic/organic mass ratio on the morphology Fig. 1 illustrated the TEM analysis results of hybrid pigment with different mass ratio of inorganic/organic. It could be found that the morphology, particle size and distribution of prepared hybrid pigments changed obviously with the mass ratio of inorganic/organic. With the increase in inorganic mass fraction, the hybrid pigments turned from irregularly shaped (Fig. 1a and b) to almost round shaped (Fig. 1c and d). In addition, the particle size of prepared hybrid pigments gradually decreased when the inorganic/organic mass ratio increased from 1/1 to 4/1, and their particle size distribution became more and more uniform. From what stated above, it could be concluded that the morphology, particle size and distribution of prepared pigments could be controlled by the mass ratio of inorganic/organic. In addition, as shown in Fig. 1e, the particle size of SiO2 was approximately 30e50 nm, and Fig. 1f illustrated that the SiO2 was encapsulate by organic pigment composite to form a coreeshell structure. 3.1.2. Effects of SiO2/TiO2 mass ratio on the morphology The morphology of hybrid pigments with different mass ratio of SiO2/TiO2 was observed by TEM, and the results were shown in Fig. 2. As shown in Fig. 2d, the particles with large size had a lattice spacing of ca. 0.32 nm corresponded to the (110) planes of rutile TiO2, suggesting that the particles with a large particle size of 200e300 nm in prepared hybrid pigments were TiO2. From Fig. 2aec, it could be found that the SiO2/organic pigment composites were combined on the surface of TiO2, and their
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Scheme 1. Mixed coupling equation for the preparation of organic pigment composite.
combination style changed with the increase in SiO2/TiO2 mass ratio. In the hybrid pigment with low SiO2/TiO2 mass ratio, the TiO2 particles were fully coated by the SiO2/organic pigment composite. However, in the hybrid pigment with high SiO2/TiO2 mass ratio, the SiO2/organic pigment composite was covered by the TiO2 particles. 3.1.3. Effects of inorganic/organic and SiO2/TiO2 on color performance The color performance of prepared hybrid pigment with different mass ratio of inorganic/organic and SiO2/TiO2 were tested and compared, and the results were shown in Table 2. As mentioned above, the hybrid with SiO2/TiO2 could reduce the particle size of organic pigment, which was responsible for the higher color strength of Hybrid-1/1 and Hybrid-2/1. However, with continuous increase in the mass ratio of inorganic/organic, the TiO2 mass fraction in hybrid pigment also increased, which resulted in the low color strength of hybrid pigments with higher mass ratio of inorganic/organic and SiO2/TiO2. Also, it could be found that the L* value for hybrid pigments gradually increased with the TiO2 mass fraction, and it was even higher than that for PY13 when the TiO2 mass fraction was over 25% (Hybrid-3/1), suggesting that the hybrid pigments with higher TiO2 mass fraction showed more light. However, these hybrid pigments showed too green hue and lower yell purity than the organic pigment, which was expressed by the lower value of color coordinate a* and c*, respectively. Table 1 Samples of prepared hybrid pigments. Sample
Inorganica/organicb
SiO2/TiO2
AAMX/IRG
Hybrid-1/1 Hybrid-2/1 Hybrid-3/1 Hybrid-4/1c Hybrid-Si1/Ti1 Hybrid-Si1/Ti3 Hybrid-Si3 PY13(70)/PY83(30) PY13(60)/PY83(40) PY13(50)/PY83(50)
1:1 2:1 3:1 4:1 4:1 4:1 3:1 4:1 4:1 4:1
3:1 3:1 3:1 3:1 1:1 1:3 Without TiO2 3:1 3:1 3:1
80:20 80:20 80:20 80:20 80:20 80:20 80:20 70:30 60:40 50:50
a b c
SiO2 and TiO2 mixture. PY13 and 83 composite. Hybrid-Si3/Ti1.
3.1.4. Effects of AAMX/IRG mass ratio on color performance As the coupling component for PY13 and PY83 respectively, the AAMX and IRG had different groups on the benzene ring, which affected the color performance of organic pigments. Thus, the mass ratio of AAMX/IRG affected the color performance of prepared hybrid pigments as shown in Table 3. Obviously, due to the inherent stronger color strength of PY83 than PY13, the color strength of hybrid pigments with higher IRG mass fraction showed higher color strength. Additionally, the hybrid pigment with higher IRG mass fraction had a higher value in Chrome (c*), suggesting a more pure yellow hue. When the IRG/ AAMX increased from 20/80 to 50/50, the hybrid pigments showed an increase in red and yellow hue, which was expressed by the increase in the value of the color coordinate a* and b* respectively. For the hue angle of hybrid pigment, although it decreased with the increase in IRG/AAMX mass ratio, it was still higher than that of PY13 and lied in the yellow region of cylindrical color space (H ¼ 75e105 for yellow) [22]. 3.2. Characterization of hybrid pigment 3.2.1. FT-IR analysis of the samples The proof of the composite nature of the prepared hybrid pigments was provided by FT-IR analysis, and the results were shown Fig. 3. As illustrated in Fig. 3a, the spectra of hybrid pigments with different mass ratio of inorganic/organic were similar, and the characteristic peaks at 1510 cm1 and 1672 cm1 belonged to C]O stretching vibration absorption peak of eCONHe group and the CeC frame vibration absorption peak of phenyl ring in PY13 and PY83. In the spectra of SiO2, the characteristic peaks at 806 cm1 and 1100 cm1 corresponded to SieOeSi stretching vibration absorption peak and SieO asymmetric absorption peak. By comparison, it could be seen that in the spectra of prepared hybrid pigments the characteristic peaks of SiO2 was gradually weakened with the increase in the mass fraction of organic pigment, suggesting an encapsulation of SiO2 by organic pigment. Fig. 3b showed the spectra of TiO2 and hybrid pigments with different mass ratio of SiO2/TiO2. It could be found that the characteristic peak at 690 cm-1 corresponded to the TieOeTi stretching vibration absorption peak was only observed in a high mass
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Fig. 1. TEM patterns of Hybrid-1/1 (a), 2/1 (b), 3/1 (c), 4/1 (d), SiO2 (e) and Hybrid-Si3 (f).
fraction of TiO2, which was suggested that the high mass fraction of TiO2 deposited on the surface of SiO2/organic pigment composite, however, the low mass fraction of TiO2 was covered by the SiO2/ organic pigment composite. 3.2.2. XRD analysis of the samples The XRD analysis results of the prepared hybrid pigments with different mass ratio of inorganic/organic and SiO2/TiO2 were shown in Fig. 4. As shown in Fig. 4a, in the curve of Hybrid-4/1, the diffraction peaks of the organic pigments (2q ¼ 10.97, 17.16 , 25.73 and 27.02 ) disappeared, only a slight wide diffraction peak of SiO2 and strong diffraction peaks of TiO2 were observed. However, with the increase in the mass ration of organic/inorganic from 1:4 to 1:1, with the gradual disappearance of the diffraction peaks of SiO2
(2q ¼ 22.01 ), the diffraction peaks of organic pigments began to be observed as shown in Fig. 4b. Fig. 4c showed the analysis results of the hybrid pigments with a fixed mass ratio of inorganic/organic at 4:1 and different mass of TiO2/SiO2, it could be found that when the mass ratio of TiO2/SiO2 increased from 1:3 to 3:1, the intensity of diffraction peaks for TiO2 in the hybrid pigments gradually enhanced. In the preparation process, the SiO2 with good pore structure as shown in Fig. 4d could effectively adsorb the coupling component to its surface and pore channel, and then organic pigments was synthesized in its pore channel and on its surface when the diazonium salt was added. Thus, in a low mass ratio of organic/inorganic (Hybrid-4/1), most of organic pigment embedded in the pore channel of SiO2, and their diffraction peaks were covered by SiO2 [7]. But in a high mass ratio of organic/inorganic (Hybrid-1/1), the
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Fig. 2. TEM patterns of hybrid-Si3/Ti1 (a), Si1/Ti1 (b) and Si1/Ti3 (c) and TiO2 lattice structure (d).
organic pigment encapsulated SiO2 and covered their diffraction peaks [18]. For the TiO2 with poor pore structure, under the pH value of the reaction mixture (pH ¼ 3e4), it showed positive charged. However, the organic pigment adsorbed the anion surfactant sulphonated castor and showed negative charged [23]. Thus, the SiO2/organic pigment composite combined with TiO2 through electrical adsorption, which was the reason for the change of the intensity of diffraction peaks for TiO2 with the mass ratio of TiO2/SiO2. Based on preceding description, the proposed mechanism for the encapsulation of SiO2 by organic pigment and the combination of SiO2/organic pigment composite with TiO2 could be described schematically as shown in Scheme 2.
3.2.3. Thermal stability of the hybrid pigments The thermal stabilities of the hybrid pigments with different mass ratio of inorganic/organic and SiO2/TiO2 were tested and compared, and the results were shown in Fig. 5. As shown in Fig. 5a, the prepared hybrid pigments did not show weight loss until the temperature reached up to about 310 C, suggesting an excellent thermal stability. In addition, with the increase in the mass ratio of the inorganic/organic, the thermal stability of the hybrid pigment was gradually improved. In a high mass ratio of the inorganic/organic, the main component of the hybrid pigments was inorganic materials and they showed more characteristic of SiO2 and TiO2, which resulted in a better thermal stability. Fig. 5b showed that a higher mass ratio of TiO2/SiO2 resulted in a better thermal stability of the prepared hybrid pigments. As mentioned above, the TiO2 combined with SiO2/organic pigment composite through electrical adsorption. Therefore, in a high mass ratio of TiO2/SiO2, the TiO2 deposited on the surface of prepared
Table 2 Color coordinates of hybrid pigments with different mass ratio of inorganic/organic and SiO2/TiO2. Sample
PY13 Hybrid-1/1 Hybrid-2/1 Hybrid-3/1 Hybrid-4/1 Hybrid-Si3/Ti1 Hybrid-Si1/Ti1 Hybrid-Si1/Ti3 a
Color coordinates
Color strength (%)a
L*
a*
b*
c*
H
78.17 76.32 77.31 78.68 79.05
10.27 11.47 10.44 6.34 4.08
81.19 80.23 81.44 79.82 75.73
81.83 81.16 82.06 79.93 75.64
82.79 81.63 83.87 86.91 88.44
e 121.96 113.64 98.20 81.62
79.09 79.27
3.85 3.71
73.88 68.22
73.78 68.13
88.43 87.85
72.79 51.68
Using PY13 as standard.
Table 3 Color performance of hybrid pigments with different mass ratio of AAMX/IRG. Hybrid pigmentsa
PY13(80)/PY83(20) PY13(70)/PY83(30) PY13(60)/PY83(40) PY13(50)/PY83(50) a b
Color coordinates L
a*
b*
c*
H
79.05 79.26 78.19 77.63
4.08 7.03 9.55 10.77
75.73 78.92 79.10 79.50
75.64 78.56 78.95 79.57
88.44 86.60 84.12 83.27
Inorganic/organic ¼ 4:1 and SiO2/TiO2 ¼ 3:1. Using PY13 as standard.
Color strength (%)b 81.62 84.61 88.22 94.69
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Fig. 3. FT-IR analysis results of the hybrid pigments with different mass ratio of inorganic/organic (a) and SiO2/TiO2 (b).
hybrid pigment, which effectively improve the thermal stability of hybrid pigments [7]. 3.2.4. UVevis spectra of the hybrid pigments The UVevis diffuse-reflectance spectra of organic pigments and prepared hybrid pigments were presented in Fig. 6. Because the spectra were determined in the powder state and diffuse-reflectance mode, they helped to determine the absorbing and scattering properties of the pigments. The lower the diffusereflectance absorbance was, the higher the scattering property of the pigment was [7]. As shown in Fig. 6a, the intensity of the absorbance peaks in the UV region and visible region of 400e550 nm for the prepared hybrid pigments were lower than that for the organic pigment, indicating that the hybrid with the SiO2 and TiO2 obviously improved the photo-stability of organic pigment. Moreover, it could be found that the intensity of the absorbance peaks in 200e400 nm was gradually increased when the mass ratio of inorganic/organic increased from 1:1 to 4:1. With the increase of mass ration of inorganic/organic, the mass fraction
of TiO2 increased, which resulted in higher absorbance intensity in the UV region since the TiO2 had an obvious UV absorbance band especially under 270 nm [7]. Thus, it protected the organic pigment from UV light and caused a higher UV shielding property of hybrid pigments. Fig. 6b showed the UVevis spectra of the hybrid pigments with different mass ratio of SiO2/TiO2. It was found that the adsorption intensity of the hybrid pigments in the UV region was similar, but adsorption intensity in the wavelength of 400e550 nm decreased obviously when the mass ratio of SiO2/TiO2 decreased from 3:1 to 1:1. The higher mass fraction of TiO2 was, the more TiO2 deposited on the surface of the hybrid pigments, causing higher light scattering properties of the hybrid pigments in the visible region since the rutile TiO2 have good reflection properties in the visible to nearinfrared region [24]. 3.2.5. Heat and light resistance of prepared hybrid pigments The color change of prepared hybrid pigments, taking PY13(60)/ PY83(40) for example, after heat treatment under powder state and
Fig. 4. XRD analysis results of the prepared hybrid pigments and the pore structure of SiO2 and TiO2.
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Scheme 2. Mechanism for the preparation of hybrid pigment.
UV accelerated aging treatment of the thin film painted with prepared acrylic resin watery ink were tested and compared with PY13, and the results were shown in Fig. 7. As shown in Fig. 7a, it could be found that the DE value for hybrid pigment PY13(60)/PY83(40) was 2.39 after heating at 250 C for 30 min, which was lower than that for the PY13, suggesting that the prepared hybrid pigment possessed better heat resistance property. And as shown in Fig. 7b, after 1 h UV irradiation, the DE value of the watery ink prepared with Hybrid-PY13(60)/PY83(40) was only 0.45, which was also lower than that for the PY13,
indicating that the prepared hybrid pigment had good light resistance property due to the excellent UV shield property of SiO2 and TiO2, which was consistent with the UVevis spectra analysis results. 4. Conclusion A series of inorganiceorganic hybrid pigments were fabricated by adding inorganic mixture of SiO2 and TiO2 in preparation process of PY13 and 83 composite with a mixed coupling method. The
Fig. 5. Thermal analysis of the hybrid pigments with different mass ratio of inorganic/organic (a) and SiO2/TiO2 (b).
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Fig. 6. UVevis diffuse-reflectance spectra of the prepared hybrid pigments with different mass ratio of inorganic/organic (a) and SiO2/TiO2 (b).
Fig. 7. Heat (a) and light (b) resistance of hybrid pigment PY13(60)/PY83(40) and PY13.
inorganic/organic, SiO2/TiO2 and coupling component mass ratios could control the morphology, particle size and distribution and color performance of prepared hybrid pigments. The characterization results showed that the SiO2 was firstly encapsulated by organic pigment to form a coreeshell structure, and then combined with TiO2 through electrical adsorption. The thermal and UVevis spectra analysis results showed that the hybrid pigment showed a better thermal- and photo-stability than organic pigment. And the DE value for hybrid pigment PY13(60)/PY83(40) heated at 250 C for 30 min and irradiated under 250 W UV lamp were 2.39 and 0.45 respectively, which was lower than that for the PY13, suggesting that the prepared hybrid pigment possessed better properties of heat and light resistance than the organic pigment.
Acknowledgment This work has been partly supported by the National Natural Science Foundation of China (51178289).
References [1] Pardo R, Zayat M, Levy D. Photochromic organiceinorganic hybrid materials. Chem Soc Rev 2011;40:672e87. [2] Chen S, Sui JJ, Chen L. Positional assembly of hybrid polyurethane nanocomposites via incorporation of inorganic building blocks into organic polymer. Colloid Polym Sci 2004;283:66e73. [3] Petrovic ZS, Javni I, Waddon A, Banhegyi G. Structure and properties of polyurethane-silica nanocomposites. J Appl Polym Sci 2000;76:133e51.
[4] Sanchez C, Belleville P, Popall M, Nicole L. Applications of advanced hybrid organiceinorganic nanomaterials: from laboratory to market. Chem Soc Rev 2011;40:696e753. [5] Herbst W, Hunger K. Industrial organic pigments: production, properties, applications. 3rd ed. Weinheim: Wiley-VCH; 2006. [6] Yuan J, Xing W, Gu G, Wu L. The properties of organic pigment encapsulated with nano-silica via layer-by-layer assembly technique. Dyes Pigm 2008;76: 463e9. [7] Yuan J, Zhou S, Wu L, You B. Organic pigment particles coated with titania via solegel process. J Phys Chem B 2006;110:388e94. [8] Yuan J, Zhou S, You B, Wu L. Organic pigment particles coated with colloidal nano-silica particles via layer-by-layer assembly. Chem Mater 2005;17: 3587e94. [9] Wen Z, Feng Y, Li X, Bai Y, Tang Q, Gao Y. Fabrication of diarylide yellow pigments/modified SiO2 coreeshell hybrid composite particles for electrophoretic displays. Curr Appl Phys 2012;12:259e65. Fabjan, Skapin [10] ES AS, Skrlep L, Zivec P, Ceh M, Gabers cek M. Protection of organic pigments against photocatalysis by encapsulation. J Sol Gel Sci Technol 2012;62:65e74. [11] Tang P, Feng Y, Li D. Facile synthesis of multicolor organiceinorganic hybrid pigments based on layered double hydroxides. Dyes Pigm 2014;104:131e6. [12] Tang P, Deng F, Feng Y, Li D. Mordant yellow 3 anions intercalated layered double hydroxides: preparation, thermo-and photostability. Ind Eng Chem Res 2012;51:10542e5. [13] Jesionowski T, Przybylska A, Kurc B, Ciesielczyk F. Hybrid pigments preparation via adsorption of C.I. Mordant Red 3 on both unmodified and aminosilane-functionalised silica supports. Dyes Pigm 2011;89:127e36. [14] Jesionowski T, Binkowski S, Krysztafkiewicz A. Adsorption of the selected organic dyes on the functionalized surface of precipitated silica via emulsion route. Dyes Pigm 2005;65:267e79. [15] Fei X, Zhang T, Zhou C. Modification study involving a naphthol as red pigment. Dyes Pigm 2000;44:75e80. [16] Horiuchi S, Horie S, Ichimura K. Coreeshell structures of silicaeorganic pigment nanohybrids visualized by electron spectroscopic imaging. ACS Appl Mater Interfaces 2009;1:977e81. [17] Hayashi K, Morii H, Iwasaki K, Horie S, Horiishi N, Ichimura K. Uniformed nano-downsizing of organic pigments through coreeshell structuring. J Mater Chem 2007;17:527e30.
L. Cao et al. / Dyes and Pigments 119 (2015) 75e83 [18] Cao L, Fei X, Zhang T, Yu L, Gu Y, Zhang B. Modification of C.I. Pigment Red 21 with sepiolite and lithopone in its preparation process. Ind Eng Chem Res 2014;53:31e7. [19] Jesionowski T, Nowacka M, Ciesielczyk F. Electrokinetic properties of hybrid pigments obtained via adsorption of organic dyes on the silica support. Pigm Resin Technol 2012;41:9e19. [20] Jesionowski T, Pokora M, Tylus W, Dec A, Krysztafkiewicz A. Effect of N-2(aminoethyl)-3-aminopropyltrimethoxysilane surface modification and C.I. Acid Red 18 dye adsorption on the physicochemical properties of silica precipitated in an emulsion route, used as a pigment and a filler in acrylic paints. Dyes Pigm 2003;57:29e41.
83
[21] Tang P, Xu X, Lin Y, Li D. Enhancement of the thermo-and photostability of an anionic dye by intercalation in a zinc-aluminum layered double hydroxide host. Ind Eng Chem Res 2008;47:2478e83. P, Trojan M. Thermal synthesis of the (Bi2O3)1x (Er2O3)x pigments. [22] Sulcov a J Therm Anal Calorim 2007;88:111e3. [23] Sis H, Birinci M. Adsorption characteristics of ionic and nonionic surfactants on hydrophobic pigment in aqueous medium. Color Technol 2012;128:244e9. [24] Bendiganavale AK, Malshe VC. Infrared reflective inorganic pigments. Recent Pat Chem Eng 2008;1:67e79.