Classifications

• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B33/00—Silicon; Compounds thereof
  • C01B33/113—Silicon oxides; Hydrates thereof
  • C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
  • C01B33/18—Preparation of finely divided silica neither in sol nor in gel form; After-treatment thereof
  • C01B33/181—Preparation of finely divided silica neither in sol nor in gel form; After-treatment thereof by a dry process
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B82—NANOTECHNOLOGY
  • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
  • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B33/00—Silicon; Compounds thereof
  • C01B33/113—Silicon oxides; Hydrates thereof
  • C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
  • C01B33/18—Preparation of finely divided silica neither in sol nor in gel form; After-treatment thereof
  • C01B33/181—Preparation of finely divided silica neither in sol nor in gel form; After-treatment thereof by a dry process
  • C01B33/182—Preparation of finely divided silica neither in sol nor in gel form; After-treatment thereof by a dry process by reduction of a siliceous material, e.g. with a carbonaceous reducing agent and subsequent oxidation of the silicon monoxide formed
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/34—Silicon-containing compounds
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/34—Silicon-containing compounds
  • C08K3/36—Silica
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K9/00—Use of pretreated ingredients
  • C08K9/02—Ingredients treated with inorganic substances
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK  ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
  • C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
  • C09C1/28—Compounds of silicon
  • C09C1/30—Silicic acid
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK  ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
  • C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
  • C09C1/28—Compounds of silicon
  • C09C1/30—Silicic acid
  • C09C1/3063—Treatment with low-molecular organic compounds
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/10—Particle morphology extending in one dimension, e.g. needle-like
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/54—Particles characterised by their aspect ratio, i.e. the ratio of sizes in the longest to the shortest dimension
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/60—Particles characterised by their size
  • C01P2004/62—Submicrometer sized, i.e. from 0.1-1 micrometer
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/60—Particles characterised by their size
  • C01P2004/64—Nanometer sized, i.e. from 1-100 nanometer
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2006/00—Physical properties of inorganic compounds
  • C01P2006/12—Surface area
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2006/00—Physical properties of inorganic compounds
  • C01P2006/32—Thermal properties
  • C01P2006/33—Phase transition temperatures
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2006/00—Physical properties of inorganic compounds
  • C01P2006/60—Optical properties, e.g. expressed in CIELAB-values
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2006/00—Physical properties of inorganic compounds
  • C01P2006/80—Compositional purity

Definitions

• This invention relates to novel inorganic silicon and oxygen containing pigments. More specifically, this invention relates to fibrous inorganic compositions of silicon and oxygen which are especially useful as intermediates for making reinforcing pigments for elastomers and to methods for making the same.
• Monox or solid, particulate, disproportionated silicon monoxide (SiO .(Si) where x and y are integers, is produced by the reaction of carbon and silica at high temperatures under reducing conditions, such as in an arc furnace, and allowing the gaseous reaction products containing SiO to condense in a partial or in an essentially complete vacum or vacuum chamber or in an inert atmosphere or gas of nitrogen, argon, helium, CO, etc.
• silicon or silicon carbide can be used to produce SiO gas.
• silicon metal can carefully be oxidized to SiO gas which then can be condensed. Still other methods for making Monox can be used.
• Monox is characterized as being solid, finely-divided or particulate and exhibiting under the electron microscope a mixture of fibrous particles and non-fibrous and possibly spherical particles. If the process is conducted in a manner that the inert condensing gas and the silicon monoxide gas stream mix together with little or no turbulence, especially long and tendrilous fibers are obtained. Moreover, the amount of the non-fibrous particles is materially reduced and is less than the fibrous particles.
• the inert condensing gas also should be essentially pure, that is, it should contain only a few parts of an oxidizing gas per million parts of condensing gas, or if it is of a commercial variety containing a minor amount of oxygen or oxidizing gases, it should also contain a minor amount of an amine such as ammonia, ethyl amine and the like or a hydrogenfurnishing gas such as hydrogen, methane, ethane, etc. to remove any traces of oxidizing gas in the inert condensing gas as well as in the furnace gases.
• an amine such as ammonia, ethyl amine and the like
• a hydrogenfurnishing gas such as hydrogen, methane, ethane, etc.
• generally non-fibrous Monox can be obtained by merely blowing the silicon monoxide gas stream from the furnace with any of the above inert condensing gases, or gas mixtures, to cause turbulence in' the mixing gas
• the Monox may contain minor amounts of nitrogen, usually about 1-8% by weight of bound nitrogen probably as (SiONH);, x being an integer, i. e.,
• very little (less than 1% by weight) or no nitrogen is present in Monox if a pure inert condensing gas is used or a commercial variety of inert gas containinga hydrogen furnishing gas is used and. the silica and carbon used are very pure.
• the fibers of the fibrous type of Monox have a ratio of length to width of from about 10:1 to 50:1 or greater and exhibit a surface area of from about 60 to 200 square meters per gram although the surface area may be smaller or larger. Their average length will vary from about 50 to 600 millimicrons or higher.
• the non-fibrous particles, if any, in the mixture may have an average particle size of from about 5 to 200 mu and a surface area of from about 200 to 300 square meters per gram.
• the SiO gas is blown with an inert gas
• the generally non-fibrous particles obtained have a random range of particle sizes of from about 5 to 200 mu and a surface area of from about 200 to 300 m. /g.
• Monox particularly where the fibers are in a major amount and very long and the ratio of the length to the width of the fibers is high, is useful as a. reinforcing pigment for various elastomeric products such as rubber, vinyls, polyesterurethanes, silicones, and the like.
• Monox is brown, and, accordingly, the color of the products produced with it are brown. This color can not be masked by the use of color pigments without materially destroying the reinforcing properties imparted by the Monox.
• Another object is to provide a method for producing a composition from disproportionated silicon monoxide which is white, solid, particulate and substantially fibrous.
• Yet another object is to provide a composition of matter from disproportionated silicon monoxide which is white,'solid, particulate and substantially fibrous and is useful as a reinforcing pigment for elastomers.
• brown Monox prepared according to any one of the foregoing methods, can be converted into a light colored to white pigment by heating the Monox in the presence of the halogen gas at elevated temperatures below the temperature at which the Monox would tend to sinter or fuse. It also has been found that the halogen-containing gas can contain up to below about 66% by volume of an oxidizing gas, based on the total volume of the halogen and oxidizing gases, to reduce materially the silicon halides, especially silicon tetrahalides, produced during halogenation with retention of the original fibrous structure exhibited by the brown Monox.
• the resulting product may be further treated with steam or water to remove essentially all of the halogen adsorbed on or bound to the surfaces of the particles of the treated Monoxwithout adversely affect- I ing thenow light to white color of or the physical struc;
• the products produced by the methods of the present invention are'essentially, particulate, solid, amorphous silicas, are fibrous and/ or non-fibrous and may ormay not contain minor amounts of halogen, hydroxyl and/or*nitrogen'groups.
• the.halogen apparently reacts with the silicon metal of the solid, disproportionated silicon monoxide to remove it asa'silic'onha'lide, such as silicon tetrahalide, which'can be'subseguently *condensed' or J recovered and used as" a starting material 'for making various silicon-containing"products.
• Another byproduct can be hexahalodisiloxane.
• the removal of the silicon'by halogen does notfaffect thefibrous structure of the "original Monox particles "which" apparently retain their original shape, "lengthi'and particle size although some small voidsmayappear in'the fibers.
• Some of the bound nitrogen originally presentin"the'starting Monox may still bepresent inthe halogenated Monox. Insome cases an increase is observed in the 'surface area of the particulate material as compared to the surface area ofthe original brown Monox.
• the halogen gas orhalogen-oxidizingpgastreated solid Monox product contains a residualgajmount;usuallyup to .about 3%, by weight'of" halogen "which'canbe'gremoved entirely or almost "entirely'by treatment-with steam at elevated temperatures.
• removingentirely or almost entirely allof thehalogen means 'that insufficient halogen remains in the steamed-product to produce anoticeable effect in materials with which the product is compounded or is present in such an amount it'may be merely considered an adventitious impurity.
• 'It' ' is'not precisely known how the halogen is'bound to 'the pa-rticles of the new; pigment. It is believed that it-maybe attached or chemically bound to the surface of--thei par- 1: andgtemperatures are proper.
• halogen is both adsorbed and bound.
• Treatment with steam serves to hydrolyze the halogen contained in the new pigment and-to liberate it as hydrogen halide.
• the minor amount of halogen containedin'the Monox after treatment can be represented by the following formula:
• silica containing the minor amount of halogen-in ,the lattice. can also be represented: by the following foror (SiO Hal) x where x is an integer.
• SiO Hal SiO Hal
• x is an integer.
• Halogen atoms maybe onadjacent silicon atoms.
• feature: of the-method ofQthe' present invention is that the halogenationprocessserves to remove any traces of-metal' lie or other ionsiwhich were contained-in the silicon monoxide gasas impurities from the carbon and other source of silicon monoxide igas andwhichmay-eondense with the SiO gas also to affect adversely the purity and color of the Monox and the new pigment.
• the halogen gas used -can'..be;1chlorine, fluorine, bromine or iodine gas or mixturesthereof. It is much preferred to zusegchlorinezbecause it is more economical to use'than the :other'halogens, ii iSi not as reactive 'asfluorine' and it does haveas higha molecular iweightias iodine.
• the halogen is'employed in an' amount sufficient to react with the silicon contained -in"'the original 'brown Monox.
• -at"lea'st'2' mols ofhalogen are required forl g. atom'of silicon' althoughan excess is preferably employed to ins'ure compl'ete rea'ction and to' remove any' tr'aces of impurities.
• the oxidizing gas used with the halogen gas to control the amount of silicon-halides produced can be oxygen, water vapor, air or any other oxidizing gas which will oxidize at least part of the silicon in the Monox without adversely affecting its properties such as structure and surface area and will serve to control the amount of sili-.
• the silicon halide vapor is not thereby diluted to such an extent that it is diificult to condense.
• oxygen when using a. material such as air containing a large amount of nitrogen, the silicon halide vapor is so diluted with nitrogen that it is diflicult to condense and recover.
• an oxidizing gas up to the amounts indicated below will serve to increase the yield (weight) of pigment obtained without changing the fibrous structure exhibited by the oniginal Monox while decreasing the yield of silicon halides, especially silicon tetrahalide.
• the pigment will also contain some halogen but in a lesser amount than when halogen gas alone was used.
• the oxidizing gas When using the oxidizing gas with the halogen-containing gas, they are preferably mixed together in a volume ratio below about 2:1 or, in other Words, the volume of oxidizing gas, exclusive of inert gas such as nitrogen when for example air is used, should be less than 66% of the total volume of the halogen and oxidizing gases. Preferably the volume of oxidizing gas should not exceed 50% of the total. At or above 66% of oxidizing gas, a reduction in the total amount of fibers and a shortening of the length of the fibers of the resulting pigment occurs due to melting and/or sintering such that a large proportion becomes non-fibrous and/or spherical in shape.
• halogen gas prepared before treatment with halogen gas. It can be permitted to stand in air at room temperature where some of the silicon is oxidized to form a film of silica over the surface of the silicon particles. So long as the film has not been produced at or subjected to high temperatures to cause fusion, subsequent halogenation will remove the remaining silicon metal. However, if the oxide film has been fused, halogen gas or the halogen-oxidizing gas mixture cannot penetrate the fused silica layer'to remove the silicon and provide a light colored to white product.
• Treatment of the halogenated product with steam to remove halogen may proceed at elevated temperature for a period of time and in an amount sufiicient to remove all or essentially all of the halogen contained in the products, although, in general, temperatures for steam treatment may be lower than those required for halogenation since the halogen is readily removed. It has been found that a relatively short treatment time, usually not more than from about 2 to 3 hours, where the original halogenation required from 50 to 80 minutes, will remove the residual halogen.
• a product containing the same can be used for many purposes and in some instances the presence of nitrogen is of particular advantage since the nitrogen confers some alkalinity on the product so that it is not as acid as a product containing no nitrogen, for example, a product derived from Monox made in a pure inert gas or in a somewhat impure inert condensing gas containing hydrogen.
• the Mono-x In the process of halogenating the Mono-x, it can be placed in a tube in an amount sufiicient to fill the tube without interfering with the passage of the halogen containing gas and then treated with said gas at a temperature of at least about 600 C. Since the reaction with halogen is exothermic, the temperature of the reaction should not be allowed to reach the fusion temperature of the Monox and preferably 'should not go above about 1100" C. to avoid fusing or sintering of the particles of the Monox. While the melting point of silica varies from, about 1470 to 1710 C. and of silicon is about 1420 C., the fusion or softening point of the Monox particles or new pigment will be somewhat less due to their high surface area and small particle size.
• reaction temperature should not exceed about 1100" C. at which temperature appreciable fusion or sintering does not occur.
• the silicon halide gas produced during the reaction serves to dilute the halogen and to cool it and the Monox or the product somewhat during the reaction, it .still may be necessary to externally cool the tube or other reaction chamber to maintain the temperature below about 1100 C.
• cooling may be efiected by reducing the volume or amount of halogen gas to reduce the rate of reaction, or by diluting the halogen gas with a cool inert gas such as nitrogen.
• the minimum temperature required to obtain improvement in color should be about 600 C.
• the operating temperature should be from about 700 to 900 C. in which range a white colored pigment is produced under the best operating and economic conditions.
• the silicon tetrahalide produced can be collected in an ice-cooled receiver or by other means during the run and used in further processes of making silicon-containing compounds which are well known in the art.
• the Monox may. be continuously treated in an inclined rotary kiln wherein the Monox is introduced at the upper end of the kiln and proceeds gradually downward while the halogen gas is introduced at the opposite end of the kiln and passes up through the kiln to react with the Monox.
• the Monox and halogen gas can pass concurrently through the kiln.
• Processes using fluidized beds can also be employed. Such processes are continuous and thereby contribute to the economy of the operation.
• Still other apparatus and techniques can be employed. It will be appreciated that such apparatus should be suitably protected to prevent contamination or corrosion from the halogen used and should contain suitable means to prevent leakage of such gas which might be hazardous.
• treatment will vary according .to the size of the apparatus employed, the amount of pigment: involved, degree of agitationand the reaction temperatures produced, being careful to avoida condition-where the reaction or treating temperatures are ashigh as, the .fusion point of the Monox or the silicon dioxide containing compound being treated.
• the halogencontaining compounds of the present invention can be used as starting materials or intermediates inother processes to provide surface coatedtpigments, useful ,as, reinforcing agents in elastomeric compounds or canbeutreatedwith a material .such as steamtoremovethe halogen contained therein and used directly in elastomeric-materials. Ad-.
• the halogen-free light colored to white pigment can be coated with various materials such as alcohols, amines, silicone resins and the like to change the surface condition of the pigment before it is incorporatedinto the elastomer. While this invention has been described with particularv reference to treatment of the brown fibrous or substantially fibrous forms of Monox which ofier the greatest improvement; in elastomeric products, particularlyrubber, it isapparent that the above remarks will apply tothe brown non fibrousorsnbstantially spherical formsofMonox which reinforce to a lesser degree but which are still usefulas arcinforcing pigment and can also be usedtas aloading material, filler and so fo-rth in variouselastomers.
• the light colored to white halogen-free pigmentsprepared-by the method of the. present invention will alsov find utility in other organic compositions such as-inthermoplastics and thermosetting plastics, in hard rubbers, in rigid vinyls, in resins, in ce-' ramic compositions, in insulating compositions,; in lubri-,
• the pigments of the present invention are particularly useful in IeinfoIcing elastomeric materials.
• elastomeric materials which .can be used with these pigments are natural and synthetic vulcanizablezrubberssuchas natural rubber, whichis essentially a polymer of isoprene, balata, gutta percha, polychloroprene and the rub bery polymers of open-chain conjugated dienes, dienes especially having from 4to 8 carbon atoms suehas butadiene-1,3, isoprene, 2-3 dirnethyl butadiene-.l,3 and the like, or the rubbery copolymers, terpolymers and the like of these and similar conjugated dienes with each other r vwith at east e -p e abl m nomeri t r a such as isobutylene, styrene, acrylonitrile, methyl acrylate,
• Still other polymers can beemployed such as those formed by 1 the copolymerization of dienes withalkyl acrylates, by the polymerization of alkyl acrylates alone and by the polymerization of analkyl acrylate-with at least one other olefinicallyv unsaturated monomer, which then are hydrolyzed to obtain curable. -COOH groups.
• polymers having -COOH groups polymers having groups such as CQOR COCI, CN, CONI-[ COONl-I and COOMe, where Meis-a metal, and the like and which are convertible to COOH-groups by ammonolysis, hydrol ysis, or similar reaetiorl fon example, by treating such polymers with dilute mineral acids, HCl or H 50 or concentrated or .,-pr eferablyvdilute KOH or NaOH, canv also be employed after such groups have been converted to a curable COOH' group Polymers having S0 11, SO H or PO H groups, or other acid groups, or deriva-.
• groups such as CQOR COCI, CN, CONI-[ COONl-I and COOMe, where Meis-a metal, and the like and which are convertible to COOH-groups by ammonolysis, hydrol ysis, or similar reaetiorl fon example, by treating such polymers with dilute mineral acids,
• polyester urethanes can also be usefully employed;.they., areformed by the-reaction ofan organic diisocyanatel compound with,a hydroxyl containingv polyester reaction, product ofa,dib asic acidi and a glycol and cross linked,
• an. elastomeriecompositionwill contain from about 25 to. 45% by weightofthe pigment of this invention, to from,v about to 55%, by weight of the elastomer exclusivet of other compounding ingredients.
• fungicides, andso forth may beernployed with the elastomeric compositions.
• elastomer ororganic polymer is converted, under ;the action ofheanlight, or vnlcanizing, cross-linking com densingand/ or other agent, into a useful material as is Curing? is;
• the use of the pigment treated as described gressively growing section of white pigment in the reacherein to remove halogen and particularly in the form tion tube.
• the light gray product may still be useful of fibers with or without bound nitrogen, not only affords where a white product is not' absolutely required.
• the samples were white and parable to those imparted by carbon black compounds colored bands appeared on the exit end of the reaction but'also permits the obtainment of light colored to white tube which were water soluble and were found to contain elastomeric materials.
• the pigment obferric, sodium and ammonium chlorides on analysis.
• the tained according to the present invention has little coveriron, sodium and ammonium apparently had been coning power, elastomeric compositions reinforced with such tained in the original brown Monox as impurities and pigment can be pigmented or dyed to provide colored had sublimed as chlorides during the reaction. Similar elastomeric materials which are not obtainable with runs were conducted in which the temperature was alcarbon black nor to any degree with the original brown lowed to run up to 1100. The resulting products were Monox. Since the pigment of the present invention has still white.
• the, surfacesof thesilicon particles are in a very active state or'at a higher temperature than the temperatureofthe mass which facilitates sintering, fusion or agglomerationof the particles because itis noted that, when chlorine is usedsalone or oxygen is used with chlorine'in: a volumeratio oflup to. below 2:1, no visible. evidence of sintering occurs at 800C. or even up to 1100 C. Accordingly, it is apparent that oxygen should not be mixed in large amounts withthechlorine if sintering is to be avoided.
• EXAMPLE III The-pigment obtained from Monox chlorinated at 700-800 C. according to Example I, above, was treated. for about one hour with steam at'a temperature above 100 C. in the tube described in Example I and'which wasata temperature of about 800 C. Hydrogen chloride was given. oif: After completion of the run the product was analyzed. The analysis showed that it still contained some nitrogen, as was present in the starting material, and also contained 0.07% by weight of chlorine showingthatall of the chlorine introduced by chlorination had been removed.- Subsequent treatment for an hour with steam underthe same conditions resulted in the removal of some of the nitrogen as ammonia. This product was also analyzed and'shown to contain 005% by weight of chlorine and 2.38% by weight ofnitrogen. Both productshad the samefibrous structure and particle size. of the startingnbrown;Monox and white chlorinated Monox of ExarnpleI and were white in color.
• This. 1 example illustrates the fact 1 that oxygencan be mixed withthe chlorine: gasup to, below- Table B' Composition containing Composition containing Pigment A. Pigment B.
• compositions were thencompared with. a rigid;
• silicone gum stock X-95 100 Dicumyl peroxide I 2 Stress strain at R. T.; cure 15' 300 F., press; 24
• This example illustrates that the pigment produced by the method of the present invention can be usefully employed in silicone rubber compositions to make light colored products.
• the present invention teaches that light colored to white silicon and oxygen containing fibrous and/ or nonfibrous materials may be obtained by the treatment of brown Monox with halogen gas in a certain elevated temperature range to remove the Si in the Monox .as a silicon halide.
• the resulting product exhibits the same structure as the starting material and may have a higher surface area. It is useful as an intermediate in preparing pigments for reinforcing elastomers.
• the small amount of halogen obtained in such product can readily be removed by subsequent treatment with steam to produce products directly useful as a reinforcing pigment.
• the treatment with halogen can be controlled by employing oxygen to reduce the amount of silicon halide obtained While still giving a light colored to white product having an increased silica content and the same physical form.
• the product produced by the method of the present invention will have great utility as a pigment which not only reinforces elastomeric materials but also permits the obtainment of light to white and even variously colored elastomeric materials.
• the method which comprises treating a brown, particulate, disproportionated solid selected from the group consisting of silicon monoxide and silicon monoxide containing from about 1 to 8% by weight of bound nitrogen at a temperature of from about 600 C. to below the fusion point of said solid with a halogen gas in an amount suflicient to react with at least a portion of the silicon in said solid to form gaseous silicon halides and to leave a light colored to white, solid, particulate, silicon diox de composition containing halogen in an amount not in excess of about 3% by weight.
• said halogen gas contains additionally an oxidizing gas in an amount up to below 66% by volume of the total volume of said halogen and oxidizing gases.
• the method which comprises treating a brown, particulate, substantially fibrous, disproportionated solid se" lected from the group consisting of silicon monoxide and silicon monoxide having from about 1 to 8% by weight of bound nitrogen at'a temperature of from about 700 to about 900 C. with chlorine gas in an amount suflicient to react with at least a portion of the silicon in said solid to form substantially gaseous silicon tetrachloride and to leave a light colored to White, solid, particulate, substantially fibrous silicon dioxide composition containing chlorine in an amount not in excess of about 3% by Weight.
• composition according to claim 15 in which said halogen is chlorine.
• a composition according to claim 15 characterized further by being substantially fibrous.
• A- composition according to claim i 21 in which the 3. esmethqd w ch c mp se t eat ng a solid 17. prising silicon monoxide at a temperature of from about halogenwgesjn an amount sufiicient to react with atleast a portion of the silicon in said solid to form gaseous:

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Citations (7)

• 0
  • NL NL104714D patent/NL104714C/xx active
• 1955
  • 1955-12-22 US US554614A patent/US2865778A/en not_active Expired - Lifetime
• 1956
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