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Preparation of organic additive-treated, pyrogenic silica-encapsulated titanium dioxide particles

Inactive Publication Date: 2005-10-27
EI DU PONT DE NEMOURS & CO
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0007] One aspect of this invention is to provide a composition comprising a titanium dioxide particle having on the surface of said particle a substantially encapsulating layer comprising a pyrogenically-deposited metal oxide; said substantially encapsulating layer having on its surface at least one organic surface treatment material selected from an organo-silane, an organo-siloxane, a fluoro-silane, an organo-phosphonate, an organo-acid phosphate, an organo-pyrophosphate, an organo-polyphosphate, an organo-metaphosphate

Problems solved by technology

However, a problem associated with use of these surface treated particles is their inability to varying degrees to resist the UV light induced formation of chromophores (typically yellow) when the particles are incorporated into polymer matrices possessing (in concert) certain types of phenolic stabilizers (such as, for example, butylated hydroxytoluene or butylated hydroxyanisole) and hindered amine light stabilizers (such as, for example, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate).
Another problem is their inability to yield particle / polymer composites that possess any significant photodurability, that is, resistance of the particle / polymer composite to UV light induced degradation.
However, a serious disadvantage of this solution is that the resulting metal oxide shell is prone to moisture retention and / or moisture generation which can, under high temperature fabrication conditions, result in the formation of the aforementioned polymer matrix imperfections, e.g., lacing in high temperature thin film fabrication.

Method used

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  • Preparation of organic additive-treated, pyrogenic silica-encapsulated titanium dioxide particles

Examples

Experimental program
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Effect test

example 1

[0117] Approximately 10 metric tons of pigmentary sized titanium dioxide particles (rutile crystalline phase) substantially encapsulated with about 2.0 wt % pyrogenic silica were produced using commercial scale equipment according to the teaching of U.S. Patent Publication No. 2003 / 0051635. An acidic, aqueous slurry of this material (˜380 g / L) was adjusted to a pH value of ˜8 (sodium hydroxide) and the residual chlorine present in said slurry neutralized. Said slurry was then acidified temporarily to pH 6 (sulfuric acid), subsequently re-adjusted to pH 8.5 (sodium hydroxide) and finally filtered (rotary drum filter). The produced filter cake was removed from the filter apparatus and dropped onto a conveying screw where neat octyltriethoxysilane (OTES) was added to said cake by peristaltic pump. The resulting pigment / OTES mixture was then fed directly to a spray dryer. The resultant dried product (dryer exit temperature ˜100° C.) was then pneumatically conveyed to a fluid energy mill...

example 2

[0118] Approximately 55 metric tons of pigmentary sized titanium dioxide particles (rutile crystalline phase) substantially encapsulated with about 1.5 wt % pyrogenic silica were produced using commercial scale equipment according to the teaching of U.S. patent Publication No. 2003 / 0051635. An acidic, aqueous slurry of this material (˜350 g / L) was adjusted to a pH value of 4.7 (sodium hydroxide) and the residual chlorine present in said slurry neutralized. Said slurry was then filtered using a press plate filter at pH values between 4.0 (pH reductions performed using hydrochloric acid) and 5.1 (pH increases performed using sodium hydroxide). The produced filter cake was conveyed to a flash dryer where said cake was simultaneously dried and treated with varying amounts of neat octyltriethoxysilane (OTES) which was injected directly into the dryer body. The resultant dried product (dryer exit temperature ˜120° C.) was then conveyed to a fluid energy mill (steam micronizer) where it wa...

example 3

[0119] Approximately 194 metric tons of pigmentary sized titanium dioxide particles (rutile crystalline phase) substantially encapsulated with about 2.0 wt % pyrogenic silica were produced using commercial scale equipment according to the teaching of U.S. patent Publication No. 2003 / 0051635. An acidic, aqueous slurry of this material (˜350 g / L) was adjusted to a pH value of 8.0 (sodium hydroxide) and the residual chlorine present in said slurry neutralized. Said slurry was then filtered using a press plate filter at pH values between 4.5 (pH reductions performed using hydrochloric acid) and 8.8 (pH increases performed using sodium hydroxide). The produced filter cake was conveyed to a flash dryer where said cake was simultaneously dried and treated with varying amounts of neat trimethylolpropane (TMP), which was injected directly into the dryer body. The resultant dried product (dryer exit temperature ˜120° C.) was then conveyed to a fluid energy mill (steam micronizer) where it was...

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Abstract

One aspect of the invention is to provide a composition comprising a titanium dioxide particle having on the surface of said particle a substantially encapsulating layer comprising a pyrogenically-deposited metal oxide; said substantially encapsulating layer having on its surface at least one organic surface treatment material selected from an organo-silane, an organo-siloxane, a fluoro-silane, an organo-phosphonate, an organo-acid phosphate, an organo-pyrophosphate, an organo-polyphosphate, an organo-metaphosphate, an organo-phosphinate, an organo-sulfonic compound, a hydrocarbon-based carboxylic acid, an associated ester of a hydrocarbon-based carboxylic acid, a derivative of a hydrocarbon-based carboxylic acid, a hydrocarbon-based amide, a low molecular weight hydrocarbon wax, a low molecular weight polyolefin, a co-polymer of a low molecular weight polyolefin, a hydrocarbon-based polyol, a derivative of a hydrocarbon-based polyol, an alkanolamine, a derivative of an alkanolamine, an organic dispersing agent, or a mixture thereof. Another aspect of the invention is to provide processes for producing said composition.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims the benefit of U.S. Provisional Application No. 60 / 565,773, filed Apr. 27, 2004 incorporated by reference herein in its entirety.FIELD OF THE INVENTION [0002] This invention relates to a process for producing titanium dioxide particles suitable for incorporation at high loadings into polymer matrices, said particles possessing the attributes of a high degree of polymer additive derived discolouration resistance, good photodurability, excellent volatilization resistance, high dispersibility, good processing in high load polymer matrices, excellent optical properties, and high bulk density. BACKGROUND OF THE INVENTION [0003] The surface application of certain organosilicon compounds to initially untreated, chloride process-derived titanium dioxide particles has been described for allowing incorporation of the particles at high loadings, high processing rates and with a high degree of dispersion into various thermop...

Claims

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Application Information

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IPC IPC(8): C01G23/04C08K3/22C08K9/02C08K9/04C08K9/06C08L101/00C09C1/36
CPCC01P2004/62Y10T428/2998C01P2006/11C01P2006/60C01P2006/62C01P2006/63C01P2006/64C08K9/02C08K9/04C08K9/06C09C1/3669C09C1/3676C09C1/3684C09C1/3692Y10T428/2995Y10T428/2991C01P2006/10C09C1/00C09C1/36
Inventor BIRMINGHAM, JOHN NICHOLASDE LA VEAUX, STEPHAN CLAUDEHSU, YUNGHSING SAMSONJERNAKOFF, PETERLEARY, KEVIN JOSEPHMUSICK, CHARLES DAVIDNIEDENZU, PHILIPP M.SUBRAMANIAN, NARAYANAN S.
Owner EI DU PONT DE NEMOURS & CO
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