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Rheoflow DS-425 is one of the most important and abundant oxides on earth, constituting about 60% weight of the earth’s crust as silica itself or in combination with other metal oxides in silicates.
Rheoflow DS-425 commonly is found as sand in the vast ocean and river shores, their beds, deserts, rocks, and minerals.
Rheoflow DS-425 exists in several structural forms: polymorphic crystalline silica, synthetic quartz crystals, amorphous silica, and vitreous silica.
CAS Number: 7631-86-9
Molecular Formula: O2Si
Molecular Weight: 60.08
EINECS Number: 231-545-4
Synonyms: Dioxosilane, Silicon dioxide, Silica, Silicic anhydride, Silica, amorphous, Amorphous silica, Colloidal silica, Diatomaceous silica, White carbon, Cab-O-Sil M-5, Aerosil (fumed silica), Sipernat, Ultrasil VN 3, Ultrasil VH 3, Vulkasil S, Santocel, Zeofree 80, Snowtex O, Snowtex 30, Zorbax Sil, Porasil, Carplex, Carplex 30, Carplex 80, Neosil, Neosyl, Siloxid, Zipax, Corasil II, Tokusil TPLM, Extrusil, Acticel, Dri-Die, Manosil VN 3, Wessalon, SILICA GEL 60 PF254 FOR PREPARATIVE LAYE;LICHROSORB SI 100 (10 MYM) 10 G;TLC-SILICA GEL 60 GF254 MEAN PARTICLE SI;LICHROSORB SI 100 (10 MYM) 100 G;SEA SAND EXTRA PURE 5 KG;SILICA GEL 60 GF254 FOR THIN-LAYER CHROM;SILICA GEL 60 PF254 + 366 FOR PREPARATIV;SEA SAND EXTRA PURE 25 KG
Rheoflow DS-425 occurs almost everywhere on earth.
This classification is not complete as there are other forms of silica synthesized for specialized applications.
Rheoflow DS-425 is a modified acrylic copolymer.
Rheoflow DS-425 acts as an excellent wetting & dispersing agent.
It shows rapid degassing after manufacture of paints & putties and has good flow & leveling properties.
Rheoflow DS-425 is suitable for polyester putties, UV-curing coating systems and solvent based coatings.
Rheoflow DS-425 is an unsaturated polycarboxylic acid polymer.
Acts as a wetting and dispersing agent.
Rheoflow DS-425 prevents cratering, pinholes, fish eyes, has excellent de-aerating and good film appearance.
Rheoflow DS-425 is suitable for industrial coatings, architectural coatings and coil coatings.
Rheoflow DS-425 is a processing additive and flow modifier used primarily in rubber and elastomer compounding.
It is designed to improve the flow behavior of rubber compounds during mixing and shaping operations, helping the material fill molds more uniformly and process more easily.
By enhancing flow, Rheoflow DS-425 contributes to more stable and efficient processing.
From a formulation perspective, Rheoflow DS-425 is a commercial mixture rather than a single chemical substance.
Rheoflow DS-425 is typically based on fatty-acid derivatives and lubricating components that reduce internal friction within the rubber compound.
Because Rheoflow DS-425 is a formulated product, it does not have a unique CAS number, and regulatory documentation refers to the CAS numbers of its individual constituents.
In industrial use, Rheoflow DS-425 is applied to reduce compound viscosity and improve dispersion of fillers and other additives.
This leads to better homogeneity, smoother extrusion or calendering, and improved surface quality of finished rubber products.
The additive also helps lower energy consumption during mixing by improving compound workability.
Rheoflow DS-425 is valued for its ability to support consistent processing and productivity in high-volume rubber manufacturing.
Rheoflow DS-425 can shorten mixing times, improve mold filling, and reduce defects related to poor flow or incomplete filling.
As part of the Rheoflow DS-425 range from Rhein Chemie/LANXESS, it is positioned as a reliable rubber-processing auxiliary that enhances process efficiency and compound performance.
Rheoflow DS-425 is a specialty internal processing aid developed to optimize the flow and rheological behavior of rubber compounds during mixing, extrusion, calendering, and molding operations.
It is designed to act within the rubber matrix rather than on the mold surface, improving the mobility of polymer chains and reducing resistance to flow.
This results in smoother processing and more uniform material behavior under shear.
In terms of composition, Rheoflow DS-425 is a commercial formulation, not a single chemical substance.
It typically contains organic flow-promoting and lubricating components, often based on fatty or wax-like structures, selected for their compatibility with common elastomers.
Because it is a mixture, it does not have its own CAS number, and safety or regulatory documentation refers to the CAS numbers of the individual ingredients.
During compounding, Rheoflow DS-425 is used to reduce mixing torque and compound viscosity, which can shorten mixing times and lower energy consumption.
Improved flow also facilitates better incorporation and dispersion of fillers, curatives, and other additives. This contributes to more homogeneous compounds and more predictable processing behavior.
In downstream processing, such as extrusion or molding, Rheoflow DS-425 helps ensure better mold filling and dimensional stability of rubber parts.
By improving flow characteristics, it reduces the risk of defects such as weld lines, flow marks, rough surfaces, or incomplete cavity filling.
This is particularly beneficial for complex or thin-walled rubber components.
Rheoflow DS-425 is commonly used in the production of technical rubber goods, including automotive parts, seals, hoses, profiles, and industrial elastomer components.
It supports high-throughput manufacturing by improving process stability and reducing scrap rates.
As part of the Rheoflow DS-425, it is positioned as a reliable rubber-processing auxiliary that enhances productivity without significantly altering the final mechanical or dynamic properties of the rubber compound.
Melting point: >1600 °C (lit.)
Boiling point: >100 °C (lit.)
Density: 2.2–2.6 g/mL at 25 °C
Bulk density: 200–800 kg/m³
Vapor pressure: 13.3 hPa at 1732 °C
Refractive index: 1.46
Flash point: 2230 °C
Storage temperature: 2–8 °C
Solubility: practically insoluble in water and in mineral acids except hydrofluoric acid; dissolves in hot solutions of alkali hydroxides
Form: suspension
pKa: 6.65–9.8 at 20 °C
Specific gravity: 2.2
Color: white to yellow
Odor: odorless
pH: 5–8 (100 g/L, H₂O, 20 °C) (slurry)
Resistivity: 1 × 10²⁰ μΩ·cm
Water solubility: insoluble
Sensitive: hygroscopic
Hydrolytic sensitivity: 6 (forms irreversible hydrate)
Crystal structure: trigonal
Merck: 14,8493
Exposure limits: NIOSH IDLH 3000 mg/m³; TWA 6 mg/m³
Stability: stable
Rheoflow DS-425 is used as a rheology modifier and internal processing aid in rubber and elastomer formulations to improve compound flow during mixing, extrusion, and molding.
Rheoflow DS-425 acts by reducing internal friction between polymer chains and between the polymer and fillers, which results in lower compound viscosity and easier processing.
This improved rheological behavior supports smoother material handling throughout the production line.
Rheoflow DS-425 is supplied as a formulated additive, not a single defined molecule.
It generally consists of lubricating and flow-promoting organic components, often derived from fatty substances, which are compatible with common elastomers.
Because of its formulation-based nature, it does not carry a single CAS number, and regulatory documentation lists the CAS numbers of the individual ingredients instead.
In practical compounding, Rheoflow DS-425 is used to enhance filler dispersion, especially for reinforcing fillers such as carbon black or silica.
Better dispersion leads to more uniform mechanical properties and improved surface quality of extruded or molded parts.
The additive can also help reduce mixing temperatures and torque, contributing to more energy-efficient processing.
Rheoflow DS-425 supports stable and reproducible processing conditions in industrial rubber production.
By improving flow and mold filling, it helps minimize defects such as flow marks, poor surface finish, or incomplete cavity filling.
This makes it particularly useful in high-throughput production of technical rubber goods.
As part of the Rheoflow DS-425 is typically applied in small dosages tailored to the specific rubber formulation and processing method.
Rheoflow DS-425 is compatible with a wide range of elastomer types and is valued for improving processability without significantly affecting the final mechanical properties of the rubber compound.
Colorless amorphous (i.e., fused silica) or crystalline (i.e., quartz) material having a low thermal expansion coefficient and excellent optical transmittance in far UV.
Rheoflow DS-425 is insoluble in strong mineral acids and alkalis except HF, concentrated H3PO4, NH4 HF2 , concentrated alkali metal hydroxides.
Owing to its good corrosion resistance to liquid metals such as Si, Ge, Sn, Pb, Ga, In, Tl, Rb, Bi, and Cd, it is used as crucible container for melting these metals, while silica is readily attacked in an inert atmosphere by molten metals such as Li, Na, K Mg, and Al.
Quartz crystals are piezoelectric and pyroelectric. Maximum service temperature 1090°C.
Rheoflow DS-425, one of the most abundant materials on the earth's crust.
Rheoflow DS-425 is an example of silica.
It is used as a filler in fertilizers, and also, in the manufacture of glass, ceramics, abrasives, rubber and cosmetics.
Rheoflow DS-425 is used as a filtering agent and as a filler in construction materials, pesticides, paints, and varnishes.
The calcined version (which has been heat treated) is the most dangerous and contains crystallized silica, and should be handled as silica. See also other entries on silica
Excellent stabillity in the dispersion of pigments and extenders is essential for the manufacturing of high quality coatings. Coating properties such as color strength, brightness, gloss, haze and opacity are entirel dependent upon the degree and quality of the dispersion.
Unstable pigment dispersions cause defects such as floating, flooding, formation of benard-cells and flocculation etc..
These defects can occur after the production stage, during storage or the film formation process.
Rheoflow DS-425 is very suitable for unsaturated polyester and UV-curing systems.
Rheoflow DS-425 reduces the interfacial tension between the hydrophylic pigments/extenders and the hydrophobic binders.
Especialy it can give rapid degassing and lower viscosity propertiesin the finished products.
And also improved levelling and flow properties.
Uses Of Rheoflow DS-425:
Rheoflow DS-425 is also known as silicone dioxide.
Rheoflow DS-425 has a variety of applications: to control a product’s viscosity, add bulk, and reduce a formulation’s transparency.
Rheoflow DS-425 can also function as an abrasive.
In addition, Rheoflow DS-425 can act as a carrier for emollients, and may be used to improve a formulation’s skin feel.
Rheoflow DS-425 is porous and highly absorbent, with absorption capabilities roughly 1.5 times its weight.
A typical claim associated with silica is oil control.
Rheoflow DS-425 is found in sunscreens, scrubs, and wide range of other skin care, makeup, and hair care preparations.
It has been successfully used in hypoallergenic and allergy-tested formulations.
Rheoflow DS-425 is mined from deposits of diatomaceous soft chalk-like rock (keiselghur).
This is an important group of extender pigments, which is used in a variety of particle sizes.
They are used as a flatting agent to reduce gloss of clear coatings and to impart shear thinning flow properties to coatings.
They are relatively expensive.
Rheoflow DS-425 is used to improve processability of rubber compounds by acting as an internal flow modifier during mixing, extrusion, calendering, and molding.
Rheoflow DS-425 facilitates smoother material flow under shear, which helps rubber compounds pass more easily through dies, molds, and calender gaps.
This improves consistency and reduces processing-related difficulties.
Rheoflow DS-425 is widely used in formulations where high filler loadings are required, such as carbon black– or silica-filled rubber compounds.
By improving filler wetting and dispersion, Rheoflow DS-425 helps achieve more homogeneous compounds with stable mechanical performance.
This is particularly beneficial for technical and automotive rubber applications.
Rheoflow DS-425 is also used to reduce processing energy and mechanical stress during compounding.
Lower mixing torque and reduced viscosity lead to shorter mixing cycles and lower heat generation, which helps protect heat-sensitive ingredients and improves overall processing efficiency.
This contributes to more stable and controlled manufacturing conditions.
In molded and extruded products, Rheoflow DS-425 is applied to improve surface quality and dimensional stability.
Better flow reduces the likelihood of surface defects such as roughness, flow lines, or incomplete mold filling.
As a result, it helps increase yield and reduce scrap in high-volume rubber production.
Additionally, Rheoflow DS-425 is used in the production of automotive and industrial rubber components, including seals, gaskets, hoses, profiles, and vibration-control parts.
Its ability to enhance processing without significantly altering final physical properties makes it a valuable processing aid for a wide range of elastomer systems.
Rheoflow DS-425, amorphous is used as carriers, processing aids, anti-caking and free-flow agents in animal feed.
Defoamer applications such as paint, food, paper, textile and other industrial applications.
Synthetic silicon dioxides are used as a rheology control agent in plastics.
Rheoflow DS-425 is also used to manufacture adhesives, sealants and silicones.
Rheoflow DS-425 manufacture of glass, water glass, refractories, abrasives, ceramics, enamels; decolorizing and purifying oils, petroleum products, etc.; in scouring- and grinding-compounds, ferrosilicon, molds for castings; as anticaking and defoaming agent.
Rheoflow DS-425 is used as an internal processing aid in rubber and elastomer compounding to improve the flow and workability of compounds during mixing and shaping operations.
Rheoflow DS-425 helps reduce compound viscosity and internal friction, allowing rubber materials to be processed more easily and consistently.
This supports smoother handling during extrusion, calendering, and molding.
Rheoflow DS-425 is commonly used to improve dispersion of fillers and additives, such as carbon black, silica, and other reinforcing agents.
Better dispersion leads to more uniform mechanical properties and improved surface quality of finished rubber products.
This makes Rheoflow DS-425 particularly useful in formulations requiring high filler loadings.
Rheoflow DS-425 is also used to enhance mold filling and dimensional accuracy of molded rubber parts.
By improving rheological behavior, it reduces the risk of incomplete filling, flow marks, or surface defects.
This contributes to higher productivity and lower scrap rates in industrial rubber manufacturing.
In addition, Rheoflow DS-425 is applied to optimize processing efficiency and energy consumption.
Reduced mixing torque and shorter processing times help lower energy use and thermal stress on the rubber compound.
This supports stable, high-throughput production of technical rubber goods such as automotive components, seals, hoses, and industrial elastomer parts.
Safety Profile Of Rheoflow DS-425:
The pure unaltered form is considered a nuisance dust.
Some deposits contain small amounts of crystahne quartz and are therefore fibrogenic.
When diatomaceous earth is calcined (with or without fluxing agents) some sdica is converted to cristobalite and is therefore fibrogenic.
Tridymite has never been detected in calcined batomaceous earth.
Rheoflow DS-425 is generally regarded as having a low hazard profile when handled and used under normal industrial conditions.
As a rubber processing aid supplied as a formulated mixture, it is not classified as highly toxic. Nevertheless, standard chemical handling precautions should always be followed.
Skin contact with Rheoflow DS-425 may cause mild irritation, particularly after prolonged or repeated exposure, due to its lubricating and fatty-acid–based components.
Eye contact can result in temporary irritation, redness, or discomfort, so the use of safety glasses is recommended during handling.
Inhalation of dust, fumes, or aerosols generated during processing may cause slight respiratory irritation, especially in poorly ventilated areas.
From a fire and explosion standpoint, Rheoflow DS-425 is not considered highly flammable under normal storage and processing conditions.
However, like many organic processing additives, it may decompose at elevated temperatures and release irritating fumes.
Adequate ventilation and temperature control should therefore be maintained during processing.
Regarding environmental aspects, Rheoflow DS-425 is not expected to pose a significant environmental hazard when used as intended.
Nevertheless, uncontrolled release into soil or waterways should be avoided, as organic processing aids may have adverse effects at high concentrations.
Spills should be collected and disposed of in accordance with local regulations.
