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Silica

From 04/13/2015 through  7/30/2013

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2. Silicon dioxide, also known as silica (from the Latin silex), is a chemical compound that is an oxide of silicon with the chemical formula SiO2. It has been known since ancient times. Silica is most commonly found in nature as sand or quartz, as well as in the cell walls of diatoms (frustule).

Silica is manufactured in several forms including fused quartz, crystal, fumed silica (or pyrogenic silica), colloidal silica, silica gel, and aerogel.

Silica is used primarily in the production of glass for windows, drinking glasses, beverage bottles, and many other uses. The majority of optical fibers for telecommunications are also made from silica. It is a primary raw material for many ceramics such as earthenware, stoneware, and porcelain.

Silica is a common additive in the production of foods, where it is used primarily as a flow agent in powdered foods, or to absorb water in hygroscopic applications. It is the primary component of diatomaceous earth, which has many uses ranging from filtration to insect control. It is also the primary component of rice husk ash, which is used, for example, in filtration and cement manufacturing.

Thin films of silica grown on silicon wafers via thermal oxidation methods can be quite beneficial in microelectronics, where they act as electric insulators with high chemical stability. In electrical applications, it can protect the silicon, store charge, block current, and even act as a controlled pathway to limit current flow.

A silica-based aerogel was used in the Stardust spacecraft to collect extraterrestrial particles. Silica is also used in the extraction of DNA and RNA due to its ability to bind to the nucleic acids under the presence of chaotropes. As hydrophobic silica it is used as a defoamer component. In hydrated form, it is used in toothpaste as a hard abrasive to remove tooth plaque.

 In its capacity as a refractory, it is useful in fiber form as a high-temperature thermal protection fabric. In cosmetics, it is useful for its light-diffusing properties and natural absorbency. Colloidal silica is used as a wine and juice fining agent. In pharmaceutical products, silica aids powder flow when tablets are formed. It is also used as a thermal enhancement compound in ground source heat pump industry.”

(Silica, Wikipedia, 7/30/2013)

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1. 8,492,444 
Biogenic silica from silica-containing plant material such as rice hulls 

“Silica (silicon dioxide) occurs in crystalline and amorphous forms. Large quantities of synthetic amorphous silica are produced as pyrogenic (fumed) silicas and wet process silicas (precipitated silicas and silica gels) which are used, notably, for reinforcing elastomers, for thickening resins, paints and toothpaste, and as free-flow additives. Synthetic amorphous silica may also be ingested as a minor constituent (<2%) in a variety of food products where it serves as an anti-caking agent. Amorphous silica is also used in some pharmaceutical preparations for the same purposes.

Amorphous silica is found in nature as biogenic silica and as silica glass of volcanic origin. One form of biogenic silica, originates from the skeletons of diatoms deposited on sea floors but it contains a small amount of cristobalite (a crystalline form of silica) and quartz (another crystalline form of silica). Most producers of food and pharmaceutical products require that the amorphous silica used as an anti-caking agent contain no detectable amount of crystalline silica.

It is known that fibers of amorphous silica are produced by a variety of plants, such as sugar cane and rice. Of known plant materials, however, the rice plant is perhaps unique because of the high concentrations of silica that it contains. Whereas, the mineral content of most plants is, for example, about 1-2%, the rice plant typically has a mineral content of about 11-23%. More the mineral content of the rice plant is silica. Of the rice plant, rice straw contains about 11% silica and rice hulls typically contain about 15-23% silica.

Rice hulls are the natural sheaths that form on rice grains during their growth. They are removed during the refining of rice and are a waste or a low-value by-product of the rice milling industry. Rice straw consists of stem, leaf sheathes, leaf blades and the remains of the panicle after harvesting. Generally, the amount of rice straw obtained from rice plants is at least equal to the rough yield of rice harvested. Because of their high silica content, rice hulls and rice straw have little value as components of animal feeds. Also, because these materials have a relatively large amount of potassium that interacts with the silica at combustion temperatures to produce boiler slag and deposits, and have a large fraction of noncombustible ash, they are similarly viewed as being a poor fuel source. For these reasons, rice hulls are frequently deposited in landfills and rice straw is usually burned in the fields. Thus rice hulls and rice straw have little or no commercial value and have historically presented a disposal problem.

Recent U.S. legislation has prohibited the use of synthetics (e.g., amorphous silicas such as fumed silica) in products which are marketed as organic foods. Currently there is an exemption to this law for synthetic silica because there is no biogenic silica. The present invention provides a source of biogenic silica that can be certified as organic."

[Biogenic Silica, US Patent 8,492,444 (7/23/2013)]

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Patent Abstracts

8,492,444 
Biogenic silica from silica-containing plant material such as rice hulls 

Hammond Phoenix, Arizona, and Peirce, St Louis, Missourin, USA, produced biogenic silica from a plant material such as rice hulls, rice straw and so forth containing a significant amount of silica for use as an anti-caking agent, excipient or flavor carrier. When the plant material is certified as organic, the silica may also be certified as organic. The plant material is ground and the silica may be concentrated by carbon reduction through enzymatic treatment or burning. In some instances an antimicrobial treatment of the silica may be beneficial.

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Patent Titles

For earlier Patent Titles, go to Sorted Patents /Compounding /Silica Fillers.

2/3/2015

8,946,338
Aqueous silicon dioxide dispersions for sealant and adhesive formulations

1/20/2015

8,936,772
Silica containing particle

12/9/2014

8,907,001 
Use of a pretreated precipitated silica as a reinforcing filler for silicon elastomer and the curable silicone elastomer compositions thus obtained by cold mixing 

12/2/2014

8,901,186 
Process for producing silica-comprising dispersions comprising polyetherols or polyether amines 

11/18/2014

8,889,044 
Method for producing mesoporous silica particles 

11/11/2014

8,883,308 
High surface area fibrous silica nanoparticles 

8,883,254 
Method of synthesizing hollow silica from sodium silicate 

8,883,110 
Synthetic amorphous silica powder and method for producing same 

10/28/2014

8,871,344 
Hydrophobization treatment of silica particles 

10/21/2014

8,865,799 
Processes for making silane, hydrophobated silica, silica masterbatch and rubber products 

10/8/2013

3. 8,552,107 
Fumed silanized silica 

2. 8,551,339 
Use of silica for the removal of organosilanes 

7/23/2013

1. 8,492,444 
Biogenic silica from silica-containing plant material such as rice hulls 

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Interested!!
Bookmark this page to follow future developments!.
(RDC 7/16/2012)

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Roger D. Corneliussen
Editor
www.maropolymeronline.com

Maro Polymer Links
Tel: 610 363 9920
Fax: 610 363 9921
E-Mail: cornelrd@bee.net  

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Copyright 2013 by Roger D. Corneliussen.
No part of this transmission is to be duplicated in any manner or forwarded by electronic mail without the express written permission of Roger D. Corneliussen
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* Date of latest addition; date of first entry is 7/30/2013.