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Method of preparing hydrophobic silica

A silica, hydrophobic technology for thin material handling, instrumentation, fibrous fillers, etc.

Active Publication Date: 2009-08-26
CABOT CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, this method limits the surface treatment of silica particles to the introduction of a single type of functional group, namely trimethylsilyl

Method used

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  • Method of preparing hydrophobic silica
  • Method of preparing hydrophobic silica

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0062] To 40 kg of an acidic aqueous dispersion of silica having a pH of about 3 (OMP-1040 from Nissan Chemical) in the reactor was added 27.8 kg of 2-propanol followed by 1.84 kg of octyltriethoxysilane. While heating to 70°C, the resulting mixture was stirred rapidly with an overhead paddle stirrer while circulating through a homogenizer and held for 6 hours. To the reaction mixture was added 3.8 kg of a 3.43% by weight aqueous solution of ammonium hydroxide, and the mixture was stirred at 70° C. for a further 2.5 hours. The reaction mixture was then spray dried at a temperature of 135°C to provide hydrophobic silica particles as a dry powder. The carbon content of the silica particles was 4.28% by weight. The T2 / T3 ratio was 0.48.

Embodiment 2

[0064] To 41 kg of an acidic aqueous dispersion of silica having a pH of about 3 (OYL from Nissan Chemical) in the reactor was added 28.7 kg of 2-propanol followed by 1.87 kg of octyltriethoxysilane. While heating to 68° C., the resulting mixture was stirred rapidly with an overhead paddle stirrer and simultaneously circulated through the homogenizer and maintained this way for 7.5 hours. The reaction mixture was then spray dried at a temperature of 130°C to provide hydrophobic silica particles as a dry powder. The carbon content of the silica particles was 4.8% by weight. The T2 / T3 ratio was 1.45.

Embodiment 3

[0066] To 39 kg of an acidic aqueous dispersion of silica having a pH of about 3 (OYL from Nissan Chemical) in the reactor was added 20.7 kg of deionized water followed by 2.51 kg of hexamethyldisilazane. While heating to 50° C., the resulting mixture was stirred rapidly with an overhead paddle stirrer and simultaneously circulated through the homogenizer and maintained this way for 6 hours. For another purpose, approximately 28 L of the reaction mixture was removed and saved. To the remaining reaction mixture was added 24.6 kg of 2-propanol followed by 0.61 kg of octyltriethoxysilane. The reaction was continued at 70°C for 5.8 hours. The reaction mixture was then spray dried at 125°C to provide hydrophobic silica particles as a dry powder. The carbon content of the silica particles was 2.32% by weight. The T2 / T3 ratio was 0.51. The particle size distribution is shown in the attached figure.

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Abstract

The invention provides hydrophobic surface-treated silica particles having (1) a ratio T2:T3 of about 0.4 or more, wherein T2 is the intensity of a peak having a chemical shift in the CP / MAS<29>Si NMR spectrum centered within the range of -56 ppm to -59 ppm, and wherein T3 is the intensity of a peak having a chemical shift in the CP / MAS <29>Si NMR spectrum centered within the range of -65 ppm to -69 ppm, and (2) a ratio (T2 +T3) / (T2 +T3 +M) of greater than about 0.05, wherein M is the intensity of a peak having a chemical shift in the CP / MAS <29>Si NMR spectrum centered within the range of +7 ppm to +18 ppm. The invention also provides a method of preparing hydrophobic surface-treated silica particles.

Description

technical field [0001] The present invention relates to hydrophobic silica particles and a method for preparing the same. Background technique [0002] Hydrophobic silica particles have physical properties useful in many applications requiring a high degree of dispersibility, including use in toner compositions, as anti-blocking agents, as adhesion modifiers, and as polymer filler. Untreated silica particles are hydrophilic due to the presence of silanol groups on the surface of the untreated silica particles. By treating the hydrophilic silica particles, the silica particles can be made less hydrophilic, thereby imparting various degrees of hydrophobicity to the particles. [0003] Many different methods are known for treating the surface of silica particles. Typically, an aqueous dispersion of silica particles is treated with reactants to introduce hydrophobic functional groups onto the silica surface. In order to prevent the silica particles from agglomerating into ge...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C09C1/30
CPCC09C1/3081G03G9/09716G03G9/09725C01P2004/52C01P2002/86C01P2004/62Y10T428/2995
Inventor 乔基姆·K·弗洛斯威廉·R·威廉斯德米特里·福米特切夫
Owner CABOT CORP
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