CA1117734A - Precipitated silica - Google Patents
Precipitated silicaInfo
- Publication number
- CA1117734A CA1117734A CA000304984A CA304984A CA1117734A CA 1117734 A CA1117734 A CA 1117734A CA 000304984 A CA000304984 A CA 000304984A CA 304984 A CA304984 A CA 304984A CA 1117734 A CA1117734 A CA 1117734A
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- Prior art keywords
- din
- precipitated silica
- silane
- dimethyl
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- 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
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- 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
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- 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
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- 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
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- 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
- C09C1/3081—Treatment with organo-silicon compounds
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- 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
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- 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
- C01P2006/10—Solid density
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- 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
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- 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
- C01P2006/40—Electric properties
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- 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
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- 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
- C01P2006/90—Other properties not specified above
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- 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
- C08K2201/00—Specific properties of additives
- C08K2201/002—Physical properties
- C08K2201/005—Additives being defined by their particle size in general
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- 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
- C08K2201/00—Specific properties of additives
- C08K2201/002—Physical properties
- C08K2201/006—Additives being defined by their surface area
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- Chemical & Material Sciences (AREA)
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- Engineering & Computer Science (AREA)
- Polymers & Plastics (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Nanotechnology (AREA)
- Health & Medical Sciences (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- Composite Materials (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Materials Engineering (AREA)
- Crystallography & Structural Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Compositions Of Macromolecular Compounds (AREA)
- Silicon Compounds (AREA)
- Pigments, Carbon Blacks, Or Wood Stains (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
The invention provides a hydrophobic precipitated silica, characterized by the following data - BET surface area according to DIN 66131, 110 ? 40 sqm/g; average size of the pri-mary particles as determined by EM photographs, 15 - 22 nm; loss on drying according to DIN 55921 after 2 hours at 105°C., <2.5%;
loss on ignition (relative to the substance dried for 2 hours at 105°C) according to DIN 55921, 5.5 ? 1.5%; pH value (in a 5%
aqueous-methanolic suspension) according to DIN 53200, 7.5 ? 1.0;
conductivity (in a 4% aqueous-methanolic suspension) < 600 µS;
bulk density of the non-ventilated material according to DIN 53194, 130 ? 40 g/litre; wettability with water, <0.1; carbon content, 2.5 ? 0.6%; water absorption at 30°C and 30% RH, 1.2 ? 0.4%; at 30°C and 70% RH, 1.5 ? 0.5%. The precipitated silica is useful as a reinforcing filler in elastomeric materials including seal-ing and cable compositions.
The invention provides a hydrophobic precipitated silica, characterized by the following data - BET surface area according to DIN 66131, 110 ? 40 sqm/g; average size of the pri-mary particles as determined by EM photographs, 15 - 22 nm; loss on drying according to DIN 55921 after 2 hours at 105°C., <2.5%;
loss on ignition (relative to the substance dried for 2 hours at 105°C) according to DIN 55921, 5.5 ? 1.5%; pH value (in a 5%
aqueous-methanolic suspension) according to DIN 53200, 7.5 ? 1.0;
conductivity (in a 4% aqueous-methanolic suspension) < 600 µS;
bulk density of the non-ventilated material according to DIN 53194, 130 ? 40 g/litre; wettability with water, <0.1; carbon content, 2.5 ? 0.6%; water absorption at 30°C and 30% RH, 1.2 ? 0.4%; at 30°C and 70% RH, 1.5 ? 0.5%. The precipitated silica is useful as a reinforcing filler in elastomeric materials including seal-ing and cable compositions.
Description
The present invention relates to a hydrophobic precipi-tated silica and its use as a reinforcing filler in material which can be hardened to form elastomers.
Fillers are solid substances of usually inorganic ori-gin and varied composition. Their particles can be fine-grained to coarse-grained and can have various shapes. Such fillers are added to a chemicotechnical product in order to improve specific properties.
The present invention provides a hydrophobic precipi-10 tated silica which is characterized by the following data:
-BET surface area 110 + 40 sqm/g average size of the primary particles as determined by , EM (Electric Micrograph) photographs 15 - 22 nm loss on drying according to ~ DIN 55921 after 2 hours at j 105C ~2.5%
loss on ignition (relative to the substance dried for 2 hours at 105C.) according to DIN 55921 5.5 + 1.5%
pH value (in a 5% aqueous -methanolic suspension) according to DIN 53200 7.5 + 1.0 conductivity (in a 4%
aqueous methanolic suspension) ~600_ ~S
bulk density of the non-ventilated material according to DIN 53194 130 + 40 g/litre ~D
wettability with water <0.1 carbon content 2.5 t 0.6%
water absorption at 30C
and 30% RH 1.2 + 0.4%
at 30C and 70%RH 1.5 + 0.5~
In a preferred embodiment of the hydrophobic precipi-tated silica according to the invention the loss on drying can be from 2.5 to 0.0%. The conductivity of the hydrophobic pre-cipitated silica according to the invention can be from 50 to 1~17734 300 ~S and its wettability with water can be from 0 to 0.05.
The present invention also provides a process for producing the hydrophobic precipitated silica according to the invention in which a precipitated silica having the following physico-chemical characteristic data (obtained by separating said precipitated silica from the precipitated suspension, in-tensive washing with water and drying the precipitated hydro-philic silica for a long time):
BET surface area according to DIN 66131 ~60 - 40 sqm/g average size of the primary particles as determined by EM photographs 14 - 22 nm loss on drying according to DIN 55921 after 2 hours at 105C 2.5 - 4.0%
loss on ignition (relative to the substance dried for 2 hours at 105C) +
according to DIN 55921 3.5 - 1.0%
pH value (in a 5% aqueous suspension) according to DIN 53200 7.0 - 8.5 conductivity (in a 4% aqueous sus-pension) <600 ~S
bulk density of the non-ventilated +
substance according to DIN 53194 140 - 40 g/litre SO content (relative to the sub-st~nce dried for 2 hours at 105C) ~0.3%
Na O content (relative to the sub-stance dried for 2 hours at 105C) <0.3%
and a hydrophobic agent are put into an original precipitated suspension while maintaining an alkaline pH value, the mixture thus obtained is stirred, separated and dried for a lengthy per-iod of time and the product thus obtained is tempered for 60 to 180 minutes, preferably for 70 to 130 minutes, at a temperature of 200 to 400C and ground.
The initial precipitated suspension of the hydrophobic precipitated silica can be obtained in the following manner:
1 part by volume of water is put into a reactor, whereupon from 0.15 to 0.25 parts by volume of sodium-tetrasili-~2 lil7734 .
cate solution ~modulus of SiO2:Na2O = 3.5 and 26% of SiO2) and0.015 to 0.025 part by volume of 96% ~2SO4 are added while stirring. During the addition an alkaline pl~ value is maintained in the mixture. On completing the addition of sodium tetrasili-cate and H2SO4 the pH value of the suspension obtained is in the weakly alkaline range.
Organo-silicon compounds, which are reacted with the hydrophilic precipitated silica suspended in the aqueous phase and which have been used for this kind of reaction heretofore, ~ 10 can be used as hydrophobic agents. Organo-silicon compounds ,~ having the general formula (R3Si)aZ
are preferred. In this formula R represents identical or differ-ent monovalent hydrocarbon radicals, which are substituted and/
or polymer if required, a is 1 or 2 and Z represents halogen, hydrogen or a radical having the formula -OH, -OR, -NRX, -ONR2, -SR, -OOCR, -O-, -N(X)- or -S-, wherein R always has the above meaning for R and X represents hydrogen or has the same meaning as R. Examples of these organo-silicon compounds are hexamethyl disilizane, trimethyl silane, trimethyl chlorosilane, trimethyl ' ethoxysilane, triorgano-silyl mercaptans such as trimethyl-silyl mercaptan, triorgano-silyl acylates such as vinyl dimethyl ace-toxysilane, triorgano-silyl amines such as trimethyl-silyl-iso-propyl arnine, trimethyl-silyl-ethyl amine, dimethyl-phenyl-silyl-propyl amine and vinyl dimethyl-silyl-butyl amine, triorgano-silyl-amino oxy compounds such as diethyl-amino-oxy-trimethyl silane and diethyl-amino-oxy-dimethyl-phenyl silane as well as hexamethyl disiloxane, l,3-divinyl-tetramethyl disiloxane, 1,3-diphenyl-tetramethyl disiloxane and 1,3-diphenyl-hexamethyl di-silazane.
Further examples of organo-silicon compounds which within the scope of the invention, can be reacted with hydrophilic 11~7734 precipitated silica suspended in the aqueous alkaline phase are dimethyl dichloro-silane, dimethyl diethoxysilane, dimethyl ethoxy-silane, dimethoxy-silane, diphenyl diethoxy-silane, vinyl-~; methyl dimethoxy-silane and octamethyl cyclotetrasiloxane and/or dimethyl polysiloxanes having 2 to 12 siloxane units per molecule and containing an Si-linked hydroxyl group in each of the term-inal units.
¦ Mixtures of various organo-silicon compounds can be reacted with the precipitated silica which is in the form of an 3 lo aqueous original precipitated suspension.
~ In a preferred embodiment of the invention dimethyl 7 dichlorosilane can be used as the hydrophobic agent.
' The organo-silicon compounds, which are reacted with the hydrophilic precipitated silica in the form of aqueous alkaline original suspension, are used preferably in amounts of 5 to 30~ by weight, in each case relative to the weight of the j precipitated silica to be reacted therewith.
The present invention also provides for the use of the hydrophobic precipitated silica according to the invention as a reinforcing filler in material which is based on diorgano-poly-j siloxanes and can be hardened to elastomers. Thus, in a pre-3 ferred embodiment the hydrophobic precipitated silica according to the invention can be used in one-component silicone-rubber joint-sealing compounds.
Furthermore, said hydrophobic precipitated silica can be used in organo-polysiloxane elastomers, which can be hardened at room temperature, as for example, preferably in a two-component silicone molding material.
According to the invention the hydrophobic precipitated silica can be used in heat-vulcanized diorgano-polysiloxane elastomers, which, for example, can be used as cable-insulating material. Any diorgano-polysiloxane, which was or could be used ~117734 heretofore as a base for material hardening to organo-polysilox-ane elastomers at room temperature (RTV), at only slightly ele-vated temperature (LTV) or at high temperature (EITV) can be ;~ used as diorgano-polysiloxanes. They can be represented, for example, by the general formula Z Si(R)-o-[si(R2)o]-xsi(R)-zn j 3-n 3-n d wherein R represents identical or different monovalent hydro-~ carbon radicals which, if required, are substituted and/or ;;~ . polymer Z represents a hydroxyl group, a hydrolyzable group and/
:' or a hydrolyzable atom or if material which can be hardened at only slightly elevated temperature is present, then Z represents ~ alkenyl groups, n is 1, 2 or 3 and x represents an integer having j a value of at least 1.
j Examples of the hydrocarbon radical R are alkyl radi-i cals such as methyl, ethyl, propyl, butyl, hexyl and octyl radi-cals; alkenyl radicals such as the vinyl, allyl, ethyl-allyl and the butadienyl radical; and aryl radicals such as the phenyl and the tolyl radical.
¦ Examples of substituted hydrocarbon radicals R are particularly halogenated hydrocarbon radicals such as the 3,3,3-trifluoropropyl radical, the chloro-phenyl radical and the bromo-tolyl radical; and alkyl-cyanide radicals such as the ~-ethyl-cyanide radical.
¦ Examples of polymer (also known as "modifying") sub-stituted and non-substituted hydrocarbon radicals R are poly-styrene, polyvinyl-acetate, polyacrylate, polymethacrylate and polyacrylonitrile radicals linked by way of carbon to silicon.
At least the majority of the radicals R preferably con-sist of methyl groups primarily because they are more readily 1~177;}4 available. The other radicals R which are possibly present are particulariy vinyl and/or phenyl groups.
Particularly in case of the presence of material which - is storable if water is excluded but which hardens to elastomers at room temperature if water is admitted, Z usually represents hydrolyzable groups. Examples of these groups are amino, amido, amino-oxy, oxime, alkoxy, alkoxy-alkoxy (for example, CH3OCH2CH2O-), alkenyl-oxy (for example, H2C=(CH3)-CO), acyl-oxy and phosphate groups. Primarily because they are more readily available, acyl-oxy groups, particularly acetoxy groups are preferred as Z. How-, ever, if Z represents oxime groups like those haviny the formula -ON=C(CH3)(C2~15), then excellent results are obtained.
Examples of hydrolizable atoms Z are halogen and hydro-gen atoms.
~ Examples of alkenyl groups are particularly vinyl `~ groups.
Identical or different Z can be linked to an Si atom.
Mixtures of different diorgano-polysixanes can also be used.
By rnixing the hydrophobic precipitated silica according ~ to the invention with diorgano-polysiloxanes and if required with I further substances at room temperature or at only slightly ele-vated temperature, possibly on adding cross-linking agents, material which can be hardened to elastomers, particularly to storable elastomers when water is excluded, or material which hardens to elastomers at roo~ temperature when water is admitted, can be produced.
The mixing operation can be carried out in any known manner, for example, in mechanical mixers.
The fillers used according to the invention are prefer-3 ably applied in amounts of 5 to 50% by wei~ht, relative to the total weight of the material which can be hardened to elastomers.
1~177;}~
In the case of HTV organo-poly-siloxane elastomers from 5 to 50 by weight can be applied and in the case of RTV organo-polysil-oxane elastomers from 5 to 35% preferably 5 to 25~ by weight.
If the diorgano-polysiloxanes containing reactive ,.
terminal units contain Si-linked hydroxyl groups as the only reactive terminal units, then in order to harden said diorgano-polysiloxanes in a conventional manner or to convert them into compounds which are hardened by the moisture contained in the atmosphere, if required by adding additional water, they must be reacted in a conventional manner with cross-linking agents, if required, in the presence of a condensation catalyst. In the .~ case of HTV diorgano-polysiloxane elastomers organic peroxides, , as for example, bis-2,4-dichlorobenzoyl peroxide, benzoyl peroxide,dicumyl peroxide, tert. butyl perbenzoate or butyl peracetate, t can be used as cross-linking agents at corresponding high tempera-tures.
Organo-siloxanes, the organic substituents of which consist of methyl, ethyl, phenyl, trifluoromethyl phenyl [F3CC6H4-] or trimethyl silyl methylene radicals [(CH3)3SiCH2-], for example, dimethyl, ~iethyl, phenyl-methyl, phenyl-ethyl, ethyl-methyl, trimethyl-silyl methylene methyl, trimethyl-silyl-methylene ethyl, trifluoromethyl-phenyl methyl or trifluoromethyl-phenyl-ethyl-siloxanes or copolymers of these compounds can be used as heat-vulcanizing organo siloxanes. Moreover, the poly-mers may contain limited amounts of diphenyl-siloxane, bis-tri-methyl-silyl-methylene-siloxane, bis-trifluoromethyl-phenyl siloxane units as well as siloxanes containing units having the formula RSiol 5 and R3Sioo 5, wherein R represents one of the above radicals.
Examples of cross-linking agents are particularly silanes having the general formula R4 tSiZ't 1~177;~
wherein R has the meaning defined hereinbefore, Z represents a hydrolyzable group and/or a hydrolizable atom and t is 3 or 4.
The above examples of hydrolyzable groups Z and hydrolyzable atoms Z also apply to the hydrolyzable groups Z' and hydrolyzable atoms Z' in their entirety.
Examples of silanes having the above formula are methyl-triacetoxy silanes, isopropyl-triacetoxy silane, isopro-poxy-triacetoxy silane, vinyl-triacetoxy silane, methyl-tris-diethyl-amino-oxy silane, methyl-tris(-cyclohexyl-amino) silane, methyl-tris(-diethyl-phosphato)-silane and methyl-tris(-methyl-ethyl-ketoximo)silane.
~ Moreover, instead of using silanes having the above '~ formula or mixtures thereof, it is also possible to use, for ~, example, polysiloxanes containing at least 3 Z' groups or atoms per molecule and the silicon valencies which are not saturated by Z' groups or atoms are saturated by siloxane-oxygen atoms and if required by R groups. The best known examples of the latter kind of cross-linking agent are the polyethyl silicate having an SiO2 content of approximately 40~ by weight, hexace-thoxy disoloxane and methyl-hydrogen polysiloxanes.
~ The best known examples of condensation catalysts are ¦ tin salts of fatty acids such as dibutyl tin dilaurate, dibutyl tin diacetate and tin-(II)-octoate.
If the only active terminal units present in the dior-gano polysiloxanes containing reactive terminal units are those j with alkenyl groups, then thè hardening to elastomers can be carried out in a conventional manner with organo-polysiloxanes, which contain on the average at least 3 Si-linked hydrogen atoms per molecule such as methyl-hydrogen polysiloxanes, in the pre-sence of catalysts promoting the addition of alkenyl groups to Si-linked hydrogen such as platinum-(IV)-chloro acid. This material (LTV) can be hardened at room temperature or at only 1~177;}~
slightly elevated temperature/usually from 50 to 80C).
Finally the hardening by means of polycyclic organo-polysiloxanes in the presence of equilibrium catalysts, such as phosphorus nitxile chlorides, is mentioned as a further example.
Of course, the material which can be hardened to elas-tomers can contain, in addition to diorgano-siloxanes, precipi-tated silica aceording to the invention, cross-linking agents and cross-linking catalysts and, if required, fillers which conventionally are used usually or frequently in materials to be hardened to elastomers. Examples of these substances are fillers i having a surface area less than 50 sq m per gram, such as ~1 quartz powder, diatomaceous earth, zirconium silicate and cal-cium carbonate as well as untreated pyrogenically produced sili-con dioxide, organic resins such as polyvinyl-chloride powder, organo-polysiloxane resins, fibrous fillers such as asbestos, glass fibres and organic fibres, pigments soluble dyes, odorous substances, corrosion inhibitors, agents which stabilize the material against the effeet of water, such as acetic anhydride, agents retarding the hardening such as benzo triazole, plasti-cizers, sueh as terminal dimethyl polysiloxanes blocked by tri-methyl-siloxy-groups.
The cited eombination of physico-chemical charaeteris-tie data of the hydrophobic preeipitated siliea aeeordiny to the invention results in a highly effective reinforein~ filler be-cause of the excellent dispersibility of said silica. The equil-ibrium moisture eontent which is distinctly reduced as compared with the known precipitated silica results in advantages when processing, for example, in the no-pressure vulcanization, in which the vulcaniæates obtained have fewer blisters than those obtained when using the conventional hydrated precipitated sili-¦ ca. The low eleetrolyte eontent in combination with the low moisture eontent results in good eleetrical properties of the g _ ~1177~
vulcanizates. In cold-hardening silicone-rubber sealing com-pounds the hydrophobic precipitated silica according to the invention is favourable for the storage properties of the non-hardened material because of its low water content.
The production, the physico-chemical data and the use of the hydrophobic precipitated silica according to the invention are described in greater detail by means of the Examples hereafter.
_ample 1 Production of the Original Precipitated Suspension 10of a Hydrophilic Precipitated Silica for the Subse-quent Wet Hydrophobic Operation ~, ' 50 cu m of water are put into a reactor. 9.2 cu m of .! sodium tetrasilicate solution and 0.9 cu m of H2SO4 are then .~added while stirring. During the addition an alkaline pH value is maintained in the mixture. On completing the addition of sodium tetrasilicate solution and H2SO4 the pll value of the sus-pension thus obtained is in the alkaline range.
In order to characterize the hydrophilic precipitated silica, a portion of the suspension is filtered off, washed until its electrolyte content is low, whereupon it is dried in a drying cabinet at 105C until the weight is constant, whereupon it is ground in a pinned disc mill.
The hydrophilic precipitated silica thus obtained has the following physico-chemical characteristic data:
BET surface area according to DIN 66131 155 sq m~g average size of the primary particles as determined by EM photographs 18 - 20 nm loss on drying according to DIN 55921 after 2 hours at 105C 3.0 loss on ignition (relative to the substance dried for 2 hours at 105C) according to DIN 55921 3.3%
pH value ~in a 5% aqueous suspension) 1~177;~4 according to DIN 53200 7.7 conductivity (in a 4% aqueous sus-pension) 240 ~S
3 bulk density of the non-ventilated material according to DIN 53194 140 g/litre S2 content (relative to the sub-stance dried for 2 hours at 105C) 0.22%
Na2O content (relative to the sub-stance dried for 2 hours at 105C) 0.18 j Determination of the Electrical Conductivity ~ A sample of 4.0 g of silica is heated in a 150-litre ~4 ; 10 beaker with 50 g of water completely free from salt, whereupon the suspension is boiled for one minute while stirring. The suspension is then transferred to a 100-ml measurin~ flask, cooled ;~ and filled up to the mark with water completely free from salt.
~ After shaking, the cell of the conductivity-measuring device is 'A first rinsed with the suspension to be measured, whereupon it is filled and the cell is dipped into the suspension. ~rhe electri-cal conductivity is read on the measuring device and the tempera-ture of the suspension is determined during the measurement.
Calculation: The electrical conductivity is defined in ~S, relative to 20C.
' Example 2 Production of a Hydrophobic Precipitated Silica according to the Invention Obtained by Net Hydro-phobic Operation ~ 193 g of dimethyl dichlorosilane are added to 10 litres ¦ of an aqueous original precipitated suspension of the precipi-tated silica according to Example 1, which has a solid concentra-tion of 57.9 g per litre, while stirring intensively for 30 minutes. During the addition, the pH value of the suspension is maintained at 8.5. After a subsequent mixing period of 60 minutes the precipitated silica, 25~ of which is covered with 1~177;}~
dimethyl dichlorosilane, is separated, dried at 105C, tempered at 350C for 2.0 hours and subsequently dried.
The hydrophobic precipitation silica thus obtained has the followiny physico-chemical characteristic data:
loss on ignition at 1000C according to DIN 55921 5.5gO
humidity thereof at 105C according to DII~ 55921 0.4 f pH value according to DIN 53200 ~.0 BET surface area according to DII~
7 66131 89 sqm/g ~i 10 wettability with water 0.05%
eonduetivity 160 ~S
C eontent 2.2%
water absorption at 30C and 30% RH 1.2~
~ at 30C and 70~ RH 2.0%
?~ bulk density of the non-ventilated material according to DIN 53194 130 g/litre t Determination of the Wettability of Hydro-phobic Silicas with Water The determination of the hydrophobic silica portions which are wettable with water is described in the analytical method hereafter.
Carrying out the Determination 0.2 g of hydrophobic silica and 50 ml of distilled water are put into a 250-ml separatory funnel and shaken for 1 minute with the aid of a Turbula mixer at maximum speed.
After allowing the wetted portions to settle for a short time, 45 ml of the suspension are drawn off into an evapor-ating dish after shaking carefully, whereupon this portion of the suspension is evaporated on a water bath and then dried at 105C.
Calculation: dry residue _100 _ ~ of portions wettable weighed-in portion with water Determination of the Moisture Absorption In the determination of the moisture absorption the ~.~17734 maximum or time-dependent moisture absorption of silicas is determined as a function of both the temperature and the rela-I tive humidity of the air.
i Carrying out the Determination A silica sample of approximately 2.5 g is weighed into ~, a dry tared weighing glass with an accuracy of 0.1 mg and dried ~ for 2 hours at 105~C. After cooling, the weight is determined 3 on an analytical balance. The open weighing glass with the sam-ple is then stored in a conditioning cabinet at predetermined ~ 10 temperature and relative humidity of the air. Either a moisture J absorption-time diagram or the maximum moisture absorption can ~j then be determined.
The determination is usually carried out at:
30C and 30% relative humidity of the air 30~C and 70~ relative humidity of the air Calculation: g of portion weighed out 100 = % of moisture g of portion weighed in dried absorption sample Example 3 The Use of a Hydrophobic Precipitated Silica ~ according to the Invention in Cold-Hardening i One-Component Silicone Rubber Compounds i In this example the hydrophobic precipitated silica according to the invention and example 2 is tested as a rein-forcing filler and thixotropic agent in a one-component sili-cone-rubber joint-sealing compound (cold-vulcanizing).
In the tests the silica Aerosil 150 of the firm of Degussa and the commercial product HD~ H 2000 of the firm of Wacker are tested for comparison in the same silicone-rubber material. R
HDK H 2000 lS a highly dispersed silica, which is ~1177~4 produced by flame hydrolysis of volatile silicon compounds and is subsequently rendered hydrophobic by reaction with organo-silanes. Therefore, on the surface said silica is densely 4 covered with trimethyl silyl groups and had the following physico-chemical characteristic data:
surface area according to BET 170 + 30 sqm/y SiO2 content >97% by weight powder density (non-pressed) approximately 90g/litre moisture according to DIN 53198 process A (after 2 hours at . 10 105C) <0.6% by weight j loss on ignition according to ,j DIN 52911 (2 hours at 1000C) <2.5-o by weight ;`1 pH va]ue according to DIN 53200 j (in a 4% dispersion in water-methanol = 1:1) 6.7 - 7.7 grit according to Mocker (DIN 53580) <0.05% by weight adhering HCQ <0.020% by weight AQ2O3 <0.05gO by weight ~! F~03 <0.005% by weight Tio2 <0.003gO by weight C <3% by weight Aerosil 150 is a pyrogenically produced silica having the following physico-chemical characteristic data:
surface area according to BET 150 + 50 sqm/g average size of the primary particles 14 nm loss on drying according to DIN 53198/A (2 hours at 105C 0.5%
_ loss on ignition according to DIN 52911 (2 hours at 1000C) 1%
pH value according to DIN 53200 (in a 4% aqueous dispersion) 3.6 - 4.5 SiO2 *) 99.8%
Fillers are solid substances of usually inorganic ori-gin and varied composition. Their particles can be fine-grained to coarse-grained and can have various shapes. Such fillers are added to a chemicotechnical product in order to improve specific properties.
The present invention provides a hydrophobic precipi-10 tated silica which is characterized by the following data:
-BET surface area 110 + 40 sqm/g average size of the primary particles as determined by , EM (Electric Micrograph) photographs 15 - 22 nm loss on drying according to ~ DIN 55921 after 2 hours at j 105C ~2.5%
loss on ignition (relative to the substance dried for 2 hours at 105C.) according to DIN 55921 5.5 + 1.5%
pH value (in a 5% aqueous -methanolic suspension) according to DIN 53200 7.5 + 1.0 conductivity (in a 4%
aqueous methanolic suspension) ~600_ ~S
bulk density of the non-ventilated material according to DIN 53194 130 + 40 g/litre ~D
wettability with water <0.1 carbon content 2.5 t 0.6%
water absorption at 30C
and 30% RH 1.2 + 0.4%
at 30C and 70%RH 1.5 + 0.5~
In a preferred embodiment of the hydrophobic precipi-tated silica according to the invention the loss on drying can be from 2.5 to 0.0%. The conductivity of the hydrophobic pre-cipitated silica according to the invention can be from 50 to 1~17734 300 ~S and its wettability with water can be from 0 to 0.05.
The present invention also provides a process for producing the hydrophobic precipitated silica according to the invention in which a precipitated silica having the following physico-chemical characteristic data (obtained by separating said precipitated silica from the precipitated suspension, in-tensive washing with water and drying the precipitated hydro-philic silica for a long time):
BET surface area according to DIN 66131 ~60 - 40 sqm/g average size of the primary particles as determined by EM photographs 14 - 22 nm loss on drying according to DIN 55921 after 2 hours at 105C 2.5 - 4.0%
loss on ignition (relative to the substance dried for 2 hours at 105C) +
according to DIN 55921 3.5 - 1.0%
pH value (in a 5% aqueous suspension) according to DIN 53200 7.0 - 8.5 conductivity (in a 4% aqueous sus-pension) <600 ~S
bulk density of the non-ventilated +
substance according to DIN 53194 140 - 40 g/litre SO content (relative to the sub-st~nce dried for 2 hours at 105C) ~0.3%
Na O content (relative to the sub-stance dried for 2 hours at 105C) <0.3%
and a hydrophobic agent are put into an original precipitated suspension while maintaining an alkaline pH value, the mixture thus obtained is stirred, separated and dried for a lengthy per-iod of time and the product thus obtained is tempered for 60 to 180 minutes, preferably for 70 to 130 minutes, at a temperature of 200 to 400C and ground.
The initial precipitated suspension of the hydrophobic precipitated silica can be obtained in the following manner:
1 part by volume of water is put into a reactor, whereupon from 0.15 to 0.25 parts by volume of sodium-tetrasili-~2 lil7734 .
cate solution ~modulus of SiO2:Na2O = 3.5 and 26% of SiO2) and0.015 to 0.025 part by volume of 96% ~2SO4 are added while stirring. During the addition an alkaline pl~ value is maintained in the mixture. On completing the addition of sodium tetrasili-cate and H2SO4 the pH value of the suspension obtained is in the weakly alkaline range.
Organo-silicon compounds, which are reacted with the hydrophilic precipitated silica suspended in the aqueous phase and which have been used for this kind of reaction heretofore, ~ 10 can be used as hydrophobic agents. Organo-silicon compounds ,~ having the general formula (R3Si)aZ
are preferred. In this formula R represents identical or differ-ent monovalent hydrocarbon radicals, which are substituted and/
or polymer if required, a is 1 or 2 and Z represents halogen, hydrogen or a radical having the formula -OH, -OR, -NRX, -ONR2, -SR, -OOCR, -O-, -N(X)- or -S-, wherein R always has the above meaning for R and X represents hydrogen or has the same meaning as R. Examples of these organo-silicon compounds are hexamethyl disilizane, trimethyl silane, trimethyl chlorosilane, trimethyl ' ethoxysilane, triorgano-silyl mercaptans such as trimethyl-silyl mercaptan, triorgano-silyl acylates such as vinyl dimethyl ace-toxysilane, triorgano-silyl amines such as trimethyl-silyl-iso-propyl arnine, trimethyl-silyl-ethyl amine, dimethyl-phenyl-silyl-propyl amine and vinyl dimethyl-silyl-butyl amine, triorgano-silyl-amino oxy compounds such as diethyl-amino-oxy-trimethyl silane and diethyl-amino-oxy-dimethyl-phenyl silane as well as hexamethyl disiloxane, l,3-divinyl-tetramethyl disiloxane, 1,3-diphenyl-tetramethyl disiloxane and 1,3-diphenyl-hexamethyl di-silazane.
Further examples of organo-silicon compounds which within the scope of the invention, can be reacted with hydrophilic 11~7734 precipitated silica suspended in the aqueous alkaline phase are dimethyl dichloro-silane, dimethyl diethoxysilane, dimethyl ethoxy-silane, dimethoxy-silane, diphenyl diethoxy-silane, vinyl-~; methyl dimethoxy-silane and octamethyl cyclotetrasiloxane and/or dimethyl polysiloxanes having 2 to 12 siloxane units per molecule and containing an Si-linked hydroxyl group in each of the term-inal units.
¦ Mixtures of various organo-silicon compounds can be reacted with the precipitated silica which is in the form of an 3 lo aqueous original precipitated suspension.
~ In a preferred embodiment of the invention dimethyl 7 dichlorosilane can be used as the hydrophobic agent.
' The organo-silicon compounds, which are reacted with the hydrophilic precipitated silica in the form of aqueous alkaline original suspension, are used preferably in amounts of 5 to 30~ by weight, in each case relative to the weight of the j precipitated silica to be reacted therewith.
The present invention also provides for the use of the hydrophobic precipitated silica according to the invention as a reinforcing filler in material which is based on diorgano-poly-j siloxanes and can be hardened to elastomers. Thus, in a pre-3 ferred embodiment the hydrophobic precipitated silica according to the invention can be used in one-component silicone-rubber joint-sealing compounds.
Furthermore, said hydrophobic precipitated silica can be used in organo-polysiloxane elastomers, which can be hardened at room temperature, as for example, preferably in a two-component silicone molding material.
According to the invention the hydrophobic precipitated silica can be used in heat-vulcanized diorgano-polysiloxane elastomers, which, for example, can be used as cable-insulating material. Any diorgano-polysiloxane, which was or could be used ~117734 heretofore as a base for material hardening to organo-polysilox-ane elastomers at room temperature (RTV), at only slightly ele-vated temperature (LTV) or at high temperature (EITV) can be ;~ used as diorgano-polysiloxanes. They can be represented, for example, by the general formula Z Si(R)-o-[si(R2)o]-xsi(R)-zn j 3-n 3-n d wherein R represents identical or different monovalent hydro-~ carbon radicals which, if required, are substituted and/or ;;~ . polymer Z represents a hydroxyl group, a hydrolyzable group and/
:' or a hydrolyzable atom or if material which can be hardened at only slightly elevated temperature is present, then Z represents ~ alkenyl groups, n is 1, 2 or 3 and x represents an integer having j a value of at least 1.
j Examples of the hydrocarbon radical R are alkyl radi-i cals such as methyl, ethyl, propyl, butyl, hexyl and octyl radi-cals; alkenyl radicals such as the vinyl, allyl, ethyl-allyl and the butadienyl radical; and aryl radicals such as the phenyl and the tolyl radical.
¦ Examples of substituted hydrocarbon radicals R are particularly halogenated hydrocarbon radicals such as the 3,3,3-trifluoropropyl radical, the chloro-phenyl radical and the bromo-tolyl radical; and alkyl-cyanide radicals such as the ~-ethyl-cyanide radical.
¦ Examples of polymer (also known as "modifying") sub-stituted and non-substituted hydrocarbon radicals R are poly-styrene, polyvinyl-acetate, polyacrylate, polymethacrylate and polyacrylonitrile radicals linked by way of carbon to silicon.
At least the majority of the radicals R preferably con-sist of methyl groups primarily because they are more readily 1~177;}4 available. The other radicals R which are possibly present are particulariy vinyl and/or phenyl groups.
Particularly in case of the presence of material which - is storable if water is excluded but which hardens to elastomers at room temperature if water is admitted, Z usually represents hydrolyzable groups. Examples of these groups are amino, amido, amino-oxy, oxime, alkoxy, alkoxy-alkoxy (for example, CH3OCH2CH2O-), alkenyl-oxy (for example, H2C=(CH3)-CO), acyl-oxy and phosphate groups. Primarily because they are more readily available, acyl-oxy groups, particularly acetoxy groups are preferred as Z. How-, ever, if Z represents oxime groups like those haviny the formula -ON=C(CH3)(C2~15), then excellent results are obtained.
Examples of hydrolizable atoms Z are halogen and hydro-gen atoms.
~ Examples of alkenyl groups are particularly vinyl `~ groups.
Identical or different Z can be linked to an Si atom.
Mixtures of different diorgano-polysixanes can also be used.
By rnixing the hydrophobic precipitated silica according ~ to the invention with diorgano-polysiloxanes and if required with I further substances at room temperature or at only slightly ele-vated temperature, possibly on adding cross-linking agents, material which can be hardened to elastomers, particularly to storable elastomers when water is excluded, or material which hardens to elastomers at roo~ temperature when water is admitted, can be produced.
The mixing operation can be carried out in any known manner, for example, in mechanical mixers.
The fillers used according to the invention are prefer-3 ably applied in amounts of 5 to 50% by wei~ht, relative to the total weight of the material which can be hardened to elastomers.
1~177;}~
In the case of HTV organo-poly-siloxane elastomers from 5 to 50 by weight can be applied and in the case of RTV organo-polysil-oxane elastomers from 5 to 35% preferably 5 to 25~ by weight.
If the diorgano-polysiloxanes containing reactive ,.
terminal units contain Si-linked hydroxyl groups as the only reactive terminal units, then in order to harden said diorgano-polysiloxanes in a conventional manner or to convert them into compounds which are hardened by the moisture contained in the atmosphere, if required by adding additional water, they must be reacted in a conventional manner with cross-linking agents, if required, in the presence of a condensation catalyst. In the .~ case of HTV diorgano-polysiloxane elastomers organic peroxides, , as for example, bis-2,4-dichlorobenzoyl peroxide, benzoyl peroxide,dicumyl peroxide, tert. butyl perbenzoate or butyl peracetate, t can be used as cross-linking agents at corresponding high tempera-tures.
Organo-siloxanes, the organic substituents of which consist of methyl, ethyl, phenyl, trifluoromethyl phenyl [F3CC6H4-] or trimethyl silyl methylene radicals [(CH3)3SiCH2-], for example, dimethyl, ~iethyl, phenyl-methyl, phenyl-ethyl, ethyl-methyl, trimethyl-silyl methylene methyl, trimethyl-silyl-methylene ethyl, trifluoromethyl-phenyl methyl or trifluoromethyl-phenyl-ethyl-siloxanes or copolymers of these compounds can be used as heat-vulcanizing organo siloxanes. Moreover, the poly-mers may contain limited amounts of diphenyl-siloxane, bis-tri-methyl-silyl-methylene-siloxane, bis-trifluoromethyl-phenyl siloxane units as well as siloxanes containing units having the formula RSiol 5 and R3Sioo 5, wherein R represents one of the above radicals.
Examples of cross-linking agents are particularly silanes having the general formula R4 tSiZ't 1~177;~
wherein R has the meaning defined hereinbefore, Z represents a hydrolyzable group and/or a hydrolizable atom and t is 3 or 4.
The above examples of hydrolyzable groups Z and hydrolyzable atoms Z also apply to the hydrolyzable groups Z' and hydrolyzable atoms Z' in their entirety.
Examples of silanes having the above formula are methyl-triacetoxy silanes, isopropyl-triacetoxy silane, isopro-poxy-triacetoxy silane, vinyl-triacetoxy silane, methyl-tris-diethyl-amino-oxy silane, methyl-tris(-cyclohexyl-amino) silane, methyl-tris(-diethyl-phosphato)-silane and methyl-tris(-methyl-ethyl-ketoximo)silane.
~ Moreover, instead of using silanes having the above '~ formula or mixtures thereof, it is also possible to use, for ~, example, polysiloxanes containing at least 3 Z' groups or atoms per molecule and the silicon valencies which are not saturated by Z' groups or atoms are saturated by siloxane-oxygen atoms and if required by R groups. The best known examples of the latter kind of cross-linking agent are the polyethyl silicate having an SiO2 content of approximately 40~ by weight, hexace-thoxy disoloxane and methyl-hydrogen polysiloxanes.
~ The best known examples of condensation catalysts are ¦ tin salts of fatty acids such as dibutyl tin dilaurate, dibutyl tin diacetate and tin-(II)-octoate.
If the only active terminal units present in the dior-gano polysiloxanes containing reactive terminal units are those j with alkenyl groups, then thè hardening to elastomers can be carried out in a conventional manner with organo-polysiloxanes, which contain on the average at least 3 Si-linked hydrogen atoms per molecule such as methyl-hydrogen polysiloxanes, in the pre-sence of catalysts promoting the addition of alkenyl groups to Si-linked hydrogen such as platinum-(IV)-chloro acid. This material (LTV) can be hardened at room temperature or at only 1~177;}~
slightly elevated temperature/usually from 50 to 80C).
Finally the hardening by means of polycyclic organo-polysiloxanes in the presence of equilibrium catalysts, such as phosphorus nitxile chlorides, is mentioned as a further example.
Of course, the material which can be hardened to elas-tomers can contain, in addition to diorgano-siloxanes, precipi-tated silica aceording to the invention, cross-linking agents and cross-linking catalysts and, if required, fillers which conventionally are used usually or frequently in materials to be hardened to elastomers. Examples of these substances are fillers i having a surface area less than 50 sq m per gram, such as ~1 quartz powder, diatomaceous earth, zirconium silicate and cal-cium carbonate as well as untreated pyrogenically produced sili-con dioxide, organic resins such as polyvinyl-chloride powder, organo-polysiloxane resins, fibrous fillers such as asbestos, glass fibres and organic fibres, pigments soluble dyes, odorous substances, corrosion inhibitors, agents which stabilize the material against the effeet of water, such as acetic anhydride, agents retarding the hardening such as benzo triazole, plasti-cizers, sueh as terminal dimethyl polysiloxanes blocked by tri-methyl-siloxy-groups.
The cited eombination of physico-chemical charaeteris-tie data of the hydrophobic preeipitated siliea aeeordiny to the invention results in a highly effective reinforein~ filler be-cause of the excellent dispersibility of said silica. The equil-ibrium moisture eontent which is distinctly reduced as compared with the known precipitated silica results in advantages when processing, for example, in the no-pressure vulcanization, in which the vulcaniæates obtained have fewer blisters than those obtained when using the conventional hydrated precipitated sili-¦ ca. The low eleetrolyte eontent in combination with the low moisture eontent results in good eleetrical properties of the g _ ~1177~
vulcanizates. In cold-hardening silicone-rubber sealing com-pounds the hydrophobic precipitated silica according to the invention is favourable for the storage properties of the non-hardened material because of its low water content.
The production, the physico-chemical data and the use of the hydrophobic precipitated silica according to the invention are described in greater detail by means of the Examples hereafter.
_ample 1 Production of the Original Precipitated Suspension 10of a Hydrophilic Precipitated Silica for the Subse-quent Wet Hydrophobic Operation ~, ' 50 cu m of water are put into a reactor. 9.2 cu m of .! sodium tetrasilicate solution and 0.9 cu m of H2SO4 are then .~added while stirring. During the addition an alkaline pH value is maintained in the mixture. On completing the addition of sodium tetrasilicate solution and H2SO4 the pll value of the sus-pension thus obtained is in the alkaline range.
In order to characterize the hydrophilic precipitated silica, a portion of the suspension is filtered off, washed until its electrolyte content is low, whereupon it is dried in a drying cabinet at 105C until the weight is constant, whereupon it is ground in a pinned disc mill.
The hydrophilic precipitated silica thus obtained has the following physico-chemical characteristic data:
BET surface area according to DIN 66131 155 sq m~g average size of the primary particles as determined by EM photographs 18 - 20 nm loss on drying according to DIN 55921 after 2 hours at 105C 3.0 loss on ignition (relative to the substance dried for 2 hours at 105C) according to DIN 55921 3.3%
pH value ~in a 5% aqueous suspension) 1~177;~4 according to DIN 53200 7.7 conductivity (in a 4% aqueous sus-pension) 240 ~S
3 bulk density of the non-ventilated material according to DIN 53194 140 g/litre S2 content (relative to the sub-stance dried for 2 hours at 105C) 0.22%
Na2O content (relative to the sub-stance dried for 2 hours at 105C) 0.18 j Determination of the Electrical Conductivity ~ A sample of 4.0 g of silica is heated in a 150-litre ~4 ; 10 beaker with 50 g of water completely free from salt, whereupon the suspension is boiled for one minute while stirring. The suspension is then transferred to a 100-ml measurin~ flask, cooled ;~ and filled up to the mark with water completely free from salt.
~ After shaking, the cell of the conductivity-measuring device is 'A first rinsed with the suspension to be measured, whereupon it is filled and the cell is dipped into the suspension. ~rhe electri-cal conductivity is read on the measuring device and the tempera-ture of the suspension is determined during the measurement.
Calculation: The electrical conductivity is defined in ~S, relative to 20C.
' Example 2 Production of a Hydrophobic Precipitated Silica according to the Invention Obtained by Net Hydro-phobic Operation ~ 193 g of dimethyl dichlorosilane are added to 10 litres ¦ of an aqueous original precipitated suspension of the precipi-tated silica according to Example 1, which has a solid concentra-tion of 57.9 g per litre, while stirring intensively for 30 minutes. During the addition, the pH value of the suspension is maintained at 8.5. After a subsequent mixing period of 60 minutes the precipitated silica, 25~ of which is covered with 1~177;}~
dimethyl dichlorosilane, is separated, dried at 105C, tempered at 350C for 2.0 hours and subsequently dried.
The hydrophobic precipitation silica thus obtained has the followiny physico-chemical characteristic data:
loss on ignition at 1000C according to DIN 55921 5.5gO
humidity thereof at 105C according to DII~ 55921 0.4 f pH value according to DIN 53200 ~.0 BET surface area according to DII~
7 66131 89 sqm/g ~i 10 wettability with water 0.05%
eonduetivity 160 ~S
C eontent 2.2%
water absorption at 30C and 30% RH 1.2~
~ at 30C and 70~ RH 2.0%
?~ bulk density of the non-ventilated material according to DIN 53194 130 g/litre t Determination of the Wettability of Hydro-phobic Silicas with Water The determination of the hydrophobic silica portions which are wettable with water is described in the analytical method hereafter.
Carrying out the Determination 0.2 g of hydrophobic silica and 50 ml of distilled water are put into a 250-ml separatory funnel and shaken for 1 minute with the aid of a Turbula mixer at maximum speed.
After allowing the wetted portions to settle for a short time, 45 ml of the suspension are drawn off into an evapor-ating dish after shaking carefully, whereupon this portion of the suspension is evaporated on a water bath and then dried at 105C.
Calculation: dry residue _100 _ ~ of portions wettable weighed-in portion with water Determination of the Moisture Absorption In the determination of the moisture absorption the ~.~17734 maximum or time-dependent moisture absorption of silicas is determined as a function of both the temperature and the rela-I tive humidity of the air.
i Carrying out the Determination A silica sample of approximately 2.5 g is weighed into ~, a dry tared weighing glass with an accuracy of 0.1 mg and dried ~ for 2 hours at 105~C. After cooling, the weight is determined 3 on an analytical balance. The open weighing glass with the sam-ple is then stored in a conditioning cabinet at predetermined ~ 10 temperature and relative humidity of the air. Either a moisture J absorption-time diagram or the maximum moisture absorption can ~j then be determined.
The determination is usually carried out at:
30C and 30% relative humidity of the air 30~C and 70~ relative humidity of the air Calculation: g of portion weighed out 100 = % of moisture g of portion weighed in dried absorption sample Example 3 The Use of a Hydrophobic Precipitated Silica ~ according to the Invention in Cold-Hardening i One-Component Silicone Rubber Compounds i In this example the hydrophobic precipitated silica according to the invention and example 2 is tested as a rein-forcing filler and thixotropic agent in a one-component sili-cone-rubber joint-sealing compound (cold-vulcanizing).
In the tests the silica Aerosil 150 of the firm of Degussa and the commercial product HD~ H 2000 of the firm of Wacker are tested for comparison in the same silicone-rubber material. R
HDK H 2000 lS a highly dispersed silica, which is ~1177~4 produced by flame hydrolysis of volatile silicon compounds and is subsequently rendered hydrophobic by reaction with organo-silanes. Therefore, on the surface said silica is densely 4 covered with trimethyl silyl groups and had the following physico-chemical characteristic data:
surface area according to BET 170 + 30 sqm/y SiO2 content >97% by weight powder density (non-pressed) approximately 90g/litre moisture according to DIN 53198 process A (after 2 hours at . 10 105C) <0.6% by weight j loss on ignition according to ,j DIN 52911 (2 hours at 1000C) <2.5-o by weight ;`1 pH va]ue according to DIN 53200 j (in a 4% dispersion in water-methanol = 1:1) 6.7 - 7.7 grit according to Mocker (DIN 53580) <0.05% by weight adhering HCQ <0.020% by weight AQ2O3 <0.05gO by weight ~! F~03 <0.005% by weight Tio2 <0.003gO by weight C <3% by weight Aerosil 150 is a pyrogenically produced silica having the following physico-chemical characteristic data:
surface area according to BET 150 + 50 sqm/g average size of the primary particles 14 nm loss on drying according to DIN 53198/A (2 hours at 105C 0.5%
_ loss on ignition according to DIN 52911 (2 hours at 1000C) 1%
pH value according to DIN 53200 (in a 4% aqueous dispersion) 3.6 - 4.5 SiO2 *) 99.8%
2 3 - 14 ~
1~17734 2 3 0.003 2 0.03 I HCQ 0.025 grit according to Mocker (DIN 53580) 0.05~
wetting characteristics hydrophobic *) relative to the substance tempered for 2 hours at 1000C.
I The following formula with acetate hardener is used ; as a basis:
86.4 parts by weight of dimethyl polydisiloxane with " 10 ~ hydroxy terminal groups, viscosity 50,000 cSt.
.~ . 271 parts by weight of dimethyl polysiloxane with trimethyl-siloxy terminal groups, viscosity 1000 cSt 4.5 parts by weight of methyl-triacetoxy silane (cross-linking agent) ~ 0.005 parts by weight of dibutyl-tin diacetate plus j silica to be tested.
The silica is incorporated after adding the cross-linking agent in a planetary mixer, which can be evacuated.
The joint-sealing compound, which was still pasty, ~ and its vulcanizate, which had been hardened for 7 days in air, ! was then subjected to the following test:
a) extrudability according to ASTM 2452-69 b) stability under load according to the cap method c) modulus at 100% elongation according to d) tensile strength according to DIN 53504 e) elongation according to DIN 53504 f) tear propagation strength according to g) Shore-A hardness according to DIN 53505 The results of these tests have been compiled in Table I (see below). Compared with the known pyrogenic hydro-f 1117734 philic silicas Aerosil 150 and the hydrophobic silica HDK H 2000 the following advance in the art is evident:
~ Aerosil 150 (a trademark) can be incorporated in the -~ one-component sealing compound only up to 8%. A higher degree of filling result in a material which can be processed only with difficulty. The level of the mechanical data obtained with ~ a degree of filling of 8% corresponds to the prior art.
1~17734 2 3 0.003 2 0.03 I HCQ 0.025 grit according to Mocker (DIN 53580) 0.05~
wetting characteristics hydrophobic *) relative to the substance tempered for 2 hours at 1000C.
I The following formula with acetate hardener is used ; as a basis:
86.4 parts by weight of dimethyl polydisiloxane with " 10 ~ hydroxy terminal groups, viscosity 50,000 cSt.
.~ . 271 parts by weight of dimethyl polysiloxane with trimethyl-siloxy terminal groups, viscosity 1000 cSt 4.5 parts by weight of methyl-triacetoxy silane (cross-linking agent) ~ 0.005 parts by weight of dibutyl-tin diacetate plus j silica to be tested.
The silica is incorporated after adding the cross-linking agent in a planetary mixer, which can be evacuated.
The joint-sealing compound, which was still pasty, ~ and its vulcanizate, which had been hardened for 7 days in air, ! was then subjected to the following test:
a) extrudability according to ASTM 2452-69 b) stability under load according to the cap method c) modulus at 100% elongation according to d) tensile strength according to DIN 53504 e) elongation according to DIN 53504 f) tear propagation strength according to g) Shore-A hardness according to DIN 53505 The results of these tests have been compiled in Table I (see below). Compared with the known pyrogenic hydro-f 1117734 philic silicas Aerosil 150 and the hydrophobic silica HDK H 2000 the following advance in the art is evident:
~ Aerosil 150 (a trademark) can be incorporated in the -~ one-component sealing compound only up to 8%. A higher degree of filling result in a material which can be processed only with difficulty. The level of the mechanical data obtained with ~ a degree of filling of 8% corresponds to the prior art.
3 However, with the silica according to the invention i used in Example 2, a substantially higher level of the mechani-10 cal data is obtained at a degree of filling of 20o~ ~Ihese data satisfy the requirements to be met by high-strength sealing compounds. The extrudability of the material is fully satisfied at this degree of filling. The storage life is also good.
However, at a degree of filling of 20%~ the value level of the mechanical data of the commercial product HDK H 2000 which represents the latest state of the art, is not comparable to the vulcanizates filled with the precipitated silica according to the invention. This applies particularly to the tensile strength and the elongation, both of which are 45~ be-20 low the corresponding values of the silica according to the invention. Only on increasing the degree of filling to 25% can the data for E~DK H 2000 be fully balanced.
Surprisingly enough, it has thus been shown that when using only 20% of the precipitated silica according to the invention a property pattern which in some respect is distinctly better (than 25% of HDK H 2000) can be attained. With the appre-ciably lower costs of production as compared with pyrogenic hydrophobic silica, additional uses thus present themselves.
- 1~17734 Table I
Testing of a ~Iydrophobic Precipitated Silica according to the Invention and Example 2 in a One-Component Silicone Sealing Compound as Compared with a Pyrogenic Silica of the Prior Art .
silica type storage life stability extrudability type (%)*) lUoaddr (g/min) (cap method) _ Oflica example ,, 2 20 good good 8.2 after 0 days ~ 8.0 after 28 days '~ Aerosil .~ 150 8 good good 8 after 0 days .~ 8 after 28 days ;.~ HDK H 2000 20 good good 19 after 0 days 22 after 28 days good good 11 after 0 days 9 after 28 days , ., silica ~ype modulus 100 tensile elongation I tear Shore-~
type (%)*)(N/mn2) strength (~) propagation hardnes (N/n)m) li S(t/mm)''h .
silica example 2 20 4.6 45 780 16 1 18 Aerosil , HDK 8 3.0 10 400 1 2.5 , 20 H 2000 20 5.0 25 430 ¦ 15 24 25 6.0 45 490 1 18 1 32 _ I ,, *) % by weight, relative to total mixture.
~177;}~
Example 4 Production of a Hydrophobic Precipitated Silica according to the Invention, Obtained by Wet Hydrophobic Process ,~
175.6 g of dimethyl dichlorosilane are added to 12 litres of an original precipitation suspension of the precipi-tated silica according to Example 1 with a solid concentration of 57.9 g per litre within 30 minutes while stirring intensively ., and while maintaining a pH value of 8.5 in the suspension. After ,~ 10 a subsequent mixing time of 60 minutes, the precipitated silica, 7 20% of which is covered with dimethyl dichlorosilane, is dried at 105C, tempered for 1.5 hours, whereupon it is ~round. The precipitated silica obtained has the following physico-chemical 1 characteristic data:
.q t loss on ignition at 1000C according to DIN 55921 5.5 humidity thereof at 105C according to DI~ 55921 0.4%
pH value according to DIN 53200 7.5 BET surface area according to DIN 66131 94 sqm/g j wettability with water 0.06 ! conductivity 92 ~S
C content 2.1P6 water absorption at 30C and 30% ~i 1.3%
at 30~C and 70% Rll 2.0%
bulk density of the non-ventilated material according to DIN 53194 137 g/litre Example 5 Use of a Hydrophobic Precipitated Silica according to the Invention in Cable Material Based on Organo Polysiloxanes In this example, the hydrophobic precipitated silica according to the invention and Example 4 is incorporated in heat-. 11177;~4 vulcanizing silicone rubber as a reinforcing filler and tested for the electrical volume resistance of the vulcanizates pro-duced therewith.
s Because of its excellent dielectrical properties, heat-vulcanizing silicone rubber is also used as high-grade cable-insulating material. On account of its compactness and favour-; able dielectrical properties highly active pyrogenic silica is usually used as a reinforcing filler in this case. It is known 1 that the insulating properties are further improved if the fully ' 10 vulcanized material is subsequently subjected to a lengthy i tempering process (at least 6 hours) at elevated temperatures (approximately 200C).
In the tests for this example, the following formula was used:
100 parts by weight of diemthyl polysiloxane with i trimethyl-siloxy terminal groups and a content of vinyl groups.
j 40 parts by weight of silica 1.4 parts by weight of 50% bis-2,4-dichloro-benzoyl peroxide (as a paste in silicone oil).
vulcanization: 7 minutes at 130C.
tempering: 0 or 6 hours at 200C and 80~ relative humidity of the air.
The results of the tests as compared with Aerosil 200 R ) (a pyrogenic silica of the firm of Degussa) are shown in Figure 1. As is evident from the curves, with the precipitated silica according to the invention similarly good resistance values can be attained as with the pyrogenic silica. Moreover, it has been surprisingly found that with the silica according to the invention, the good electrical properties can also be attained without the costly tempering process mentioned herein-j before. Apart from the more favourable costs of production, ~ this is a further advantage of the precipitated silica according to the invention.
*) Aerosil 200R is a highly dispersed silica produced by flame hydrolysis of volatile silicon compounds and has the following physico-chemical characteristic data:
surface area according to BET 200 + 25 sqm/g average size of the primary particles 12 mll j bulk density (DIN 53194) 1700 ml/lOOg compressed material 1000 ml/lOOg loss on drying (DIN 53198, process A) 2 hours at 105C <1.. 5% by weight loss on ignition (DIN 52911) ~ 2 hours at 1000C ~1.5~ by weight :' pH value (DIN 53200) in a 4%
aqueous dispersion 3.6 - 4.3 ~1 SiO >99.8% by weight i AQ03 <0.05% by weight ~203 <0.003~ by weight TiO2 <0.03% by weight HCQ <0.025~ by weight grit according to Mocker (DIN 53580) 0.05% by weight I
However, at a degree of filling of 20%~ the value level of the mechanical data of the commercial product HDK H 2000 which represents the latest state of the art, is not comparable to the vulcanizates filled with the precipitated silica according to the invention. This applies particularly to the tensile strength and the elongation, both of which are 45~ be-20 low the corresponding values of the silica according to the invention. Only on increasing the degree of filling to 25% can the data for E~DK H 2000 be fully balanced.
Surprisingly enough, it has thus been shown that when using only 20% of the precipitated silica according to the invention a property pattern which in some respect is distinctly better (than 25% of HDK H 2000) can be attained. With the appre-ciably lower costs of production as compared with pyrogenic hydrophobic silica, additional uses thus present themselves.
- 1~17734 Table I
Testing of a ~Iydrophobic Precipitated Silica according to the Invention and Example 2 in a One-Component Silicone Sealing Compound as Compared with a Pyrogenic Silica of the Prior Art .
silica type storage life stability extrudability type (%)*) lUoaddr (g/min) (cap method) _ Oflica example ,, 2 20 good good 8.2 after 0 days ~ 8.0 after 28 days '~ Aerosil .~ 150 8 good good 8 after 0 days .~ 8 after 28 days ;.~ HDK H 2000 20 good good 19 after 0 days 22 after 28 days good good 11 after 0 days 9 after 28 days , ., silica ~ype modulus 100 tensile elongation I tear Shore-~
type (%)*)(N/mn2) strength (~) propagation hardnes (N/n)m) li S(t/mm)''h .
silica example 2 20 4.6 45 780 16 1 18 Aerosil , HDK 8 3.0 10 400 1 2.5 , 20 H 2000 20 5.0 25 430 ¦ 15 24 25 6.0 45 490 1 18 1 32 _ I ,, *) % by weight, relative to total mixture.
~177;}~
Example 4 Production of a Hydrophobic Precipitated Silica according to the Invention, Obtained by Wet Hydrophobic Process ,~
175.6 g of dimethyl dichlorosilane are added to 12 litres of an original precipitation suspension of the precipi-tated silica according to Example 1 with a solid concentration of 57.9 g per litre within 30 minutes while stirring intensively ., and while maintaining a pH value of 8.5 in the suspension. After ,~ 10 a subsequent mixing time of 60 minutes, the precipitated silica, 7 20% of which is covered with dimethyl dichlorosilane, is dried at 105C, tempered for 1.5 hours, whereupon it is ~round. The precipitated silica obtained has the following physico-chemical 1 characteristic data:
.q t loss on ignition at 1000C according to DIN 55921 5.5 humidity thereof at 105C according to DI~ 55921 0.4%
pH value according to DIN 53200 7.5 BET surface area according to DIN 66131 94 sqm/g j wettability with water 0.06 ! conductivity 92 ~S
C content 2.1P6 water absorption at 30C and 30% ~i 1.3%
at 30~C and 70% Rll 2.0%
bulk density of the non-ventilated material according to DIN 53194 137 g/litre Example 5 Use of a Hydrophobic Precipitated Silica according to the Invention in Cable Material Based on Organo Polysiloxanes In this example, the hydrophobic precipitated silica according to the invention and Example 4 is incorporated in heat-. 11177;~4 vulcanizing silicone rubber as a reinforcing filler and tested for the electrical volume resistance of the vulcanizates pro-duced therewith.
s Because of its excellent dielectrical properties, heat-vulcanizing silicone rubber is also used as high-grade cable-insulating material. On account of its compactness and favour-; able dielectrical properties highly active pyrogenic silica is usually used as a reinforcing filler in this case. It is known 1 that the insulating properties are further improved if the fully ' 10 vulcanized material is subsequently subjected to a lengthy i tempering process (at least 6 hours) at elevated temperatures (approximately 200C).
In the tests for this example, the following formula was used:
100 parts by weight of diemthyl polysiloxane with i trimethyl-siloxy terminal groups and a content of vinyl groups.
j 40 parts by weight of silica 1.4 parts by weight of 50% bis-2,4-dichloro-benzoyl peroxide (as a paste in silicone oil).
vulcanization: 7 minutes at 130C.
tempering: 0 or 6 hours at 200C and 80~ relative humidity of the air.
The results of the tests as compared with Aerosil 200 R ) (a pyrogenic silica of the firm of Degussa) are shown in Figure 1. As is evident from the curves, with the precipitated silica according to the invention similarly good resistance values can be attained as with the pyrogenic silica. Moreover, it has been surprisingly found that with the silica according to the invention, the good electrical properties can also be attained without the costly tempering process mentioned herein-j before. Apart from the more favourable costs of production, ~ this is a further advantage of the precipitated silica according to the invention.
*) Aerosil 200R is a highly dispersed silica produced by flame hydrolysis of volatile silicon compounds and has the following physico-chemical characteristic data:
surface area according to BET 200 + 25 sqm/g average size of the primary particles 12 mll j bulk density (DIN 53194) 1700 ml/lOOg compressed material 1000 ml/lOOg loss on drying (DIN 53198, process A) 2 hours at 105C <1.. 5% by weight loss on ignition (DIN 52911) ~ 2 hours at 1000C ~1.5~ by weight :' pH value (DIN 53200) in a 4%
aqueous dispersion 3.6 - 4.3 ~1 SiO >99.8% by weight i AQ03 <0.05% by weight ~203 <0.003~ by weight TiO2 <0.03% by weight HCQ <0.025~ by weight grit according to Mocker (DIN 53580) 0.05% by weight I
Claims (12)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. Hydrophobic precipitated silica, characterized by the following data:
BET surface area according to DIN 66131 110 ? 40 sqm/g average size of the primary particles as determined by EM photographs 15 - 22 nm loss on drying according to DIN 55921 after 2 hours at 105°C <2.5%
loss on ignition (relative to the substance dried for 2 hours at 105°C) according to DIN 55921 5.5 ? 1.5%
pH value (in a 5% aqueous-methanolic suspension) according to DIN 53200 7.5 ? 1.0 conductivity (in a 4% aqueous-methanolic suspension) <600 µS
bulk density of the non-ventilated material according to DIN 53194 130 ? 40 g/litre wettability with water <0.1 carbon content 2.5 ? 0.6%
water absorption at 30°C and 30% RH 1.2 ? 0.4%
at 30°C and 70% RH 1.5 ? 0.5%
BET surface area according to DIN 66131 110 ? 40 sqm/g average size of the primary particles as determined by EM photographs 15 - 22 nm loss on drying according to DIN 55921 after 2 hours at 105°C <2.5%
loss on ignition (relative to the substance dried for 2 hours at 105°C) according to DIN 55921 5.5 ? 1.5%
pH value (in a 5% aqueous-methanolic suspension) according to DIN 53200 7.5 ? 1.0 conductivity (in a 4% aqueous-methanolic suspension) <600 µS
bulk density of the non-ventilated material according to DIN 53194 130 ? 40 g/litre wettability with water <0.1 carbon content 2.5 ? 0.6%
water absorption at 30°C and 30% RH 1.2 ? 0.4%
at 30°C and 70% RH 1.5 ? 0.5%
2. A precipitated silica as claimed in claim 1 in which the loss on drying is from 2.5% to 0.0%; the conductivity is from 50 to 300 µS and the wettability with water is from 0 to 0.05.
3. A precipitated silica according to claim 1 or 2 present as a reinforcing filler in material which is based on diorgano polysiloxanes and can be hardened to elastomers.
4. A precipitated silica according to claim 1 or 2 present as a reinforcing filler in a one-component silicone-rubber joint-sealing compound.
5. A precipitated silica according to claim 1 or 2 present as a reinforcing filler in a silicone-rubber cable material.
6. A process for producing hydrophobic precipitated silica in which a hydrophilic precipitated silica and a hydrophobic agent are put into an initial precipitated suspension while main-taining an alkaline pH value, said precipitated silica being obtained upon separating said precipitated silica from the precipitation suspension, intensive washing with water and drying the hydrophilic precipitated silica for a lengthy period of time and having the following physico-chemical characteristic data:
BET surface area according to DIN
66131 160 ? 40 sqm/g average size of the primary particles as determined by EM photographs 14 - 22 nm loss on drying according to DIN
55921 after 2 hours at 105°C 2.5 - 4.0%
loss on ignition (relative to the substance dried for 2 hours at 105°C) according to DIN 55921 3.5 ? 1.0%
pH value ( in a 5% aqueous suspen-sion) according to DIN 53200 7.0 - 8.5 conductivity (in a 4% aqueous suspension) <600µS
bulk density of the non-ventilated substance according to DIN 53194 140 ? 40g/litre SO3 content (relative to the sub-stance dried for 2 hours at 105°C) <0.3%
Na2O content (relative to the sub-stance dried for 2 hours at 105°C) <0.3%
The mixture thus obtained is stirred, the hydrophobic precipitated silica is separated and dried for a lengthy period of time and the product thus obtained is tempered for 60 to 180 minutes at a temperature of 200 to 400°C and ground.
BET surface area according to DIN
66131 160 ? 40 sqm/g average size of the primary particles as determined by EM photographs 14 - 22 nm loss on drying according to DIN
55921 after 2 hours at 105°C 2.5 - 4.0%
loss on ignition (relative to the substance dried for 2 hours at 105°C) according to DIN 55921 3.5 ? 1.0%
pH value ( in a 5% aqueous suspen-sion) according to DIN 53200 7.0 - 8.5 conductivity (in a 4% aqueous suspension) <600µS
bulk density of the non-ventilated substance according to DIN 53194 140 ? 40g/litre SO3 content (relative to the sub-stance dried for 2 hours at 105°C) <0.3%
Na2O content (relative to the sub-stance dried for 2 hours at 105°C) <0.3%
The mixture thus obtained is stirred, the hydrophobic precipitated silica is separated and dried for a lengthy period of time and the product thus obtained is tempered for 60 to 180 minutes at a temperature of 200 to 400°C and ground.
7. A process as claimed in claim 6 in which the product obtained is tempered for 70 to 130 minutes.
8. A process as claimed in claim 6 in which the hydrophobic agent is a compound of the formula (R3Si)aZ
wherein each R is a monovalent hydrocarbon radical which may be substituted, a is 1 or 2 and Z is selected from halogen, hydrogen and a radical of the formula selected from -OR, -NRX, -ONR2 -SR, -OOCR, -O-, -N(X)- and -S-, where R is as above and X is selected from hydrogen and R.
wherein each R is a monovalent hydrocarbon radical which may be substituted, a is 1 or 2 and Z is selected from halogen, hydrogen and a radical of the formula selected from -OR, -NRX, -ONR2 -SR, -OOCR, -O-, -N(X)- and -S-, where R is as above and X is selected from hydrogen and R.
9. A process as claimed in claim 6 in which the hydrophobic agent is selected from hexamethyl disilizane, trimethyl silane, trimethylchlorosilane, trimethyl ethoxy silane, trimethyl silyl mercaptan, methyl dimethyl acetoxy silane, trimethyl silyl isopropyl amine, trimethyl silyl ethyl amine, dimethyl phenyl silyl propyl amine, vinyl dimethyl silyl butyl amine, diethyl amino oxy trimethyl silane,diethyl amino oxy dimethyl phenyl silane, hexamethyl disiloxane, 1,3-divinyl tetramethyl disiloxane, 1,3-diphenyl tetramethyl disiloxane, and 1,3-diphenyl hexamethyl disilazane.
10. A process as claimed in claim 6 in which the hydrophobic agent is selected from dimethyl dichloro-silane, dimethyl diethoxy silane, dimethyl ethoxy-silane, dimethoxy-silane, diphenyl diethoxy-silane, vinyl-methyl dimethoxy-silane and octamethyl cyclo-tetrasiloxane and dimethyl polysiloxanes having 2 to 12 siloxane units per molecule and containing an Si-linked hydroxyl group in each of the terminal units.
11. A process as claimed in claim 6 in which the hydrophobic agent is dimethyl dichlorosilane.
12. A process as claimed in claim 6, 7 or 8 in which the hydrophobic agent is present in an amount from 5 to 30%
by weight of the precipitated silica
by weight of the precipitated silica
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP2729244.0-41 | 1977-06-29 | ||
| DE19772729244 DE2729244A1 (en) | 1977-06-29 | 1977-06-29 | FELLING SILICIC ACID |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1117734A true CA1117734A (en) | 1982-02-09 |
Family
ID=6012623
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000304984A Expired CA1117734A (en) | 1977-06-29 | 1978-06-08 | Precipitated silica |
Country Status (9)
| Country | Link |
|---|---|
| JP (1) | JPS5411899A (en) |
| BE (1) | BE868524A (en) |
| CA (1) | CA1117734A (en) |
| DE (1) | DE2729244A1 (en) |
| ES (1) | ES468615A1 (en) |
| FR (1) | FR2395952A1 (en) |
| GB (1) | GB2001303B (en) |
| NL (1) | NL180015C (en) |
| SE (1) | SE432094B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7951848B2 (en) | 2005-03-17 | 2011-05-31 | Wacker Chemie Ag | Aqueous dispersions of partially hydrophobic silicas |
Families Citing this family (31)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS55154354A (en) | 1979-05-16 | 1980-12-01 | Toray Silicone Co Ltd | Silicone composition for treating glass fiber |
| DE2929587C2 (en) * | 1979-07-21 | 1981-08-27 | Degussa Ag, 6000 Frankfurt | Hydrophobic filler mixture, process for its production and its use |
| FR2474517A1 (en) * | 1979-12-20 | 1981-07-31 | Rhone Poulenc Ind | ORGANOSILIC COMPOSITIONS CONTAINING NEW PRECIPITATION SILICA WITH IMPROVED REINFORCING PROPERTIES |
| US4344800A (en) * | 1980-06-03 | 1982-08-17 | Dow Corning Corporation | Method for producing hydrophobic reinforcing silica fillers and fillers obtained thereby |
| US4529774A (en) * | 1982-08-20 | 1985-07-16 | General Electric Company | Treated silica fillers and process for making same |
| DE3309272A1 (en) * | 1983-03-15 | 1984-09-20 | Consortium für elektrochemische Industrie GmbH, 8000 München | METHOD FOR THE PRODUCTION OF PELLETIC ACID |
| JPS6122641U (en) * | 1984-07-17 | 1986-02-10 | 三菱電機株式会社 | printing device |
| JPH01185367A (en) * | 1988-01-18 | 1989-07-24 | Toshiba Silicone Co Ltd | Surface-treated polymethylsilsesquioxane powder |
| JP3534464B2 (en) * | 1994-12-22 | 2004-06-07 | 東ソー・シリカ株式会社 | Partially hydrophobized precipitated silica |
| EP0721971B1 (en) | 1995-01-13 | 2000-09-13 | Bridgestone Corporation | Process for preparing pneumatic tires |
| DE19828364A1 (en) | 1998-06-25 | 1999-12-30 | Degussa | Hydrophobic precipitated silica |
| US6051672A (en) * | 1998-08-24 | 2000-04-18 | Dow Corning Corporation | Method for making hydrophobic non-aggregated colloidal silica |
| EP1048697A3 (en) * | 1999-04-28 | 2001-02-07 | Dow Corning Corporation | Preparation of hydrophobic precipitated silica |
| US6184408B1 (en) * | 1999-04-28 | 2001-02-06 | Dow Corning Corporation | Method for preparation of hydrophobic precipitated silica |
| US6736891B1 (en) * | 1999-08-19 | 2004-05-18 | Ppg Industries Ohio, Inc. | Process for producing hydrophobic particulate inorganic oxides |
| ATE261821T1 (en) | 2000-04-11 | 2004-04-15 | Degussa | COATING INKS FOR INKJET MEDIA |
| JP4016239B2 (en) * | 2000-07-05 | 2007-12-05 | 信越化学工業株式会社 | Curable fluoropolyether rubber composition |
| JP2002241695A (en) * | 2000-12-15 | 2002-08-28 | Dow Corning Toray Silicone Co Ltd | Water-repellent silicone coating agent composition |
| DE10138491A1 (en) | 2001-08-04 | 2003-02-13 | Degussa | Process for the production of a hydrophobic precipitated silica with a high degree of whiteness and extremely low moisture absorption |
| DE10138490A1 (en) | 2001-08-04 | 2003-02-13 | Degussa | Hydrophobic precipitated silica with a high degree of whiteness and extremely low moisture absorption |
| DE10138492A1 (en) | 2001-08-04 | 2003-02-13 | Degussa | Hydrophobic, non-tempered precipitated silica with a high degree of whiteness |
| EP1295906A1 (en) * | 2001-09-20 | 2003-03-26 | Degussa AG | Silicone rubber formulations containing hydrophobic silica |
| DE10203500A1 (en) | 2002-01-30 | 2003-08-07 | Degussa | Room temperature crosslinking one-component silicone rubber formulations with hydrophobic silicas |
| EP1559744A1 (en) * | 2004-01-30 | 2005-08-03 | Rhodia Chimie | Use of a pretreated precipitated silica as a reinforcing filler for silicone elastomer and curable compositions thus obtained |
| JP2006241253A (en) | 2005-03-01 | 2006-09-14 | Shin Etsu Chem Co Ltd | Room-temperature-curable organopolysiloxane composition |
| DE102006024590A1 (en) | 2006-05-26 | 2007-11-29 | Degussa Gmbh | Hydrophilic silicic acid for sealants |
| NZ585945A (en) | 2007-11-09 | 2011-03-31 | Pacific Polymers Pty Ltd | Hydrophobic modification of mineral fillers and mixed polymer systems |
| FR2979107A1 (en) | 2011-08-16 | 2013-02-22 | Bluestar Silicones France | PROCESS FOR THE PREPARATION OF SILICA GRAFTED BY AN ORGANOSILICIE COMPOUND |
| KR20210136160A (en) | 2016-07-27 | 2021-11-16 | 와커 헤미 아게 | Method for producing modified precipitated silica and a composition containing the same |
| EP3653673A1 (en) * | 2018-11-16 | 2020-05-20 | Rhodia Operations | Organosilane-modified precipitated silica |
| WO2021093961A1 (en) * | 2019-11-14 | 2021-05-20 | Wacker Chemie Ag | Modified precipitated silicic acid with reduced moisture content |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB813453A (en) * | 1954-12-14 | 1959-05-13 | Columbia Southern Chem Corp | Silica pigments |
| DE1172245B (en) * | 1963-01-23 | 1964-06-18 | Degussa | Process for the production of a hydrophobic wet precipitated silica |
| BE628932A (en) * | 1963-02-14 | |||
| NL6502791A (en) * | 1965-03-05 | 1966-09-06 | ||
| NL7000442A (en) * | 1969-01-27 | 1970-07-29 | ||
| DE2020887B2 (en) * | 1970-04-29 | 1975-01-09 | Akzo Chemie Gmbh, 5160 Dueren | Process for the production of a low surface area silica and the use of this silica as a reinforcing filler in elastomers |
| GB1424503A (en) * | 1973-03-05 | 1976-02-11 | Cabot Corp | Precipitated silica reinforcing agents and rubber compositions containing same |
| DE2435860B2 (en) * | 1974-07-25 | 1977-10-20 | Deutsche Gold- U. Silber-Scheideanstalt, Vorm. Roessler, 6000 Frankfurt | PROCESS FOR THE PRODUCTION OF FINE PARTICLE HYDROPHOBIC SILICACIDS OR SILICATES |
| DE2628975A1 (en) * | 1976-06-28 | 1977-12-29 | Degussa | FELLING SILICIC ACID |
-
1977
- 1977-06-29 DE DE19772729244 patent/DE2729244A1/en active Granted
-
1978
- 1978-03-15 NL NLAANVRAGE7802850,A patent/NL180015C/en not_active IP Right Cessation
- 1978-04-07 ES ES468615A patent/ES468615A1/en not_active Expired
- 1978-04-12 FR FR7810791A patent/FR2395952A1/en active Granted
- 1978-06-08 CA CA000304984A patent/CA1117734A/en not_active Expired
- 1978-06-27 BE BE6046517A patent/BE868524A/en not_active IP Right Cessation
- 1978-06-28 JP JP7756978A patent/JPS5411899A/en active Granted
- 1978-06-28 SE SE7807329A patent/SE432094B/en not_active IP Right Cessation
- 1978-06-29 GB GB787828256A patent/GB2001303B/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7951848B2 (en) | 2005-03-17 | 2011-05-31 | Wacker Chemie Ag | Aqueous dispersions of partially hydrophobic silicas |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2001303A (en) | 1979-01-31 |
| NL7802850A (en) | 1979-01-03 |
| SE7807329L (en) | 1978-12-30 |
| FR2395952A1 (en) | 1979-01-26 |
| ES468615A1 (en) | 1979-08-01 |
| DE2729244A1 (en) | 1979-01-04 |
| JPS632886B2 (en) | 1988-01-21 |
| NL180015B (en) | 1986-07-16 |
| SE432094B (en) | 1984-03-19 |
| NL180015C (en) | 1986-12-16 |
| DE2729244C2 (en) | 1990-06-13 |
| FR2395952B1 (en) | 1980-09-19 |
| BE868524A (en) | 1978-12-27 |
| JPS5411899A (en) | 1979-01-29 |
| GB2001303B (en) | 1982-02-24 |
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