摘要:
Processes for making high quality PCC compositions, and the resulting PCC products thereof. A precipitated calcium carbonate (PCC) composition is prepared by a process comprising the step of wet media mill grinding an aqueous slurry of PCC made by carbonation of lime milk, with the grinding being done at a low solids content in a plurality of separate grinding stages, which can done while essentially free of the presence of organic dispersant. After the multi-stage wet grinding step, the ground PCC slurry is partially dewatered in the presence of an organic dispersant in a solid bowl centrifuge. Then, the partially dewatered PCC slurry is subjected, in the presence of an organic dispersant, to fluid shearing forces created in a rotor/stator type mixer. While these three steps are advantageously used together within a single PCC process flow for optimal effect, the individual steps also can be incorporated singly or in lesser combinations thereof into different PCC manufacturing schemes to beneficial effect. The resulting PCC compositions are endowed with reduced high-shear viscosity in aqueous slurry form at high solids content and contain PCC particles of narrower particle size distribution. PCC slurries are provided that are particularly well-suited for paper coatings applications including medium and low coating weight, woodfree paper coatings, although it has wider applicability and is by no means limited thereto. As another aspect, the additional cost otherwise associated with the use of evaporative-based dehydration procedures to increase the PCC solids content in a PCC slurry or associated with the adding of dry CaCO3 pigment to build slurry solids can be reduced or even eliminated by a facile made in a decanting operation within the inventive process flow.
摘要:
A method of preparing a polymer structured pigment slurry which comprises providing an anionic, aqueous slurry including a plurality of solid mineral particles, adding a low molecular weight, cationic polymer in an amount of less than about 0.20% by weight to the slurry and then adding a small amount of an inorganic dispersant to the polymer treated pigment slurry. The Malvern median particle size of the mineral particles treated with the polycationic polymer is less than about 20% larger than the Malvern median particle size of the untreated mineral particles.
摘要:
An improved finely divided rubber-reinforcing clay mineral composition can be produced by employing a hydrous kaolin clay surface treated with a functional silane, a methylene donor compound such as hexamethylenetetramine, and a multifunctional methylene acceptor such as resorcinol. A novel process of preparation is provided. The improved reinforcing, treated clay filler can be combined with natural or synthetic elastomer compositions which can be cured to elastomer products which have improved physical properties, such as modulus, tensile, tear, wear resistance and/or resistance to heat build-up.
摘要:
This invention has particular utility in the field of absorption spectrophotometry or colorimetry, and is particularly applicable, when incorporated in such type of equipment, as a sample detector to enable direct readings to be taken in concentration or absorbance of sample fluids or the like.
摘要:
A low visibility landing system is provided for guiding aircraft on landing approaches. The low visibility landing system may aid a pilot during landing in low visibility conditions such that an aircraft may descend to lower altitudes without visual contact with the runway than is possible with other landing systems. The system may use various navigational systems to produce a hybrid signal that may be more stable than individual signals of those navigational systems. The hybrid signal is compared to a predetermined landing approach plan to determine the deviation of the aircraft from the landing approach plan and to provide guidance to the pilot to get the aircraft back onto the landing approach plan. The system may also use multiple navigational systems to perform checks on an operation of a primary navigational system to ensure that the primary navigational system is operating accurately.
摘要:
A repulpable wax containing paper product consists essentially of a hot melt formulation with an effective amount of an inorganic mineral filler such as clay. The inorganic mineral filler is in an amount which permits the article coated with the hot melt—inorganic mineral filler formulation to be repulped and recycled.
摘要:
A method of preparing a surface treated barium sulfate product is disclosed which has improved dispersibility in end use applications such as polymeric formulations. The method includes mixing a silicon-hydride containing polysiloxane, in neat or in aqueous emulsion form, with a quantity of barium sulfate particles and then optionally drying the resultant mixture. The silicon-hydride containing polysiloxane is deposited on and chemically bonded to the surface of the barium sulfate particles.
摘要:
An effective production method for silane-treated clays having exceptional reinforcing effects with respect to rubber, and compositions using these silane-treated clays are offered. With the silane-treated clay production method, a functional silane is predispersed or emulsified in water by means of a surfactant in order to mix the functional silane with kaolin clay and thereby uniformly surface-treat the kaolin clay with the functional silane. The surfactant should preferably be a non-ionic surfactant with an HLB value in the range of 8-18. The silane-treated clay formed by surface-treating kaolin clay by means of these functional silanes characteristically contains low residual levels of the non-ionic surfactants. The functional silanes can be either vinyl or sulfur functional silanes. The silane treated clays are useful as fillers or extenders in rubber compositions, particularly those employing silicas and/or carbon blacks.
摘要:
An effective production method for silane-treated clays having exceptional reinforcing effects with respect to rubber, and compositions using these silane-treated clays are offered. With the silane-treated clay production method, a functional silane is predispersed or emulsified in water by means of a surfactant in order to mix the functional silane with kaolin clay and thereby uniformly surface-treat the kaolin clay with the functional silane. The surfactant should preferably be a non-ionic surfactant with an HLB value in the range of 8-18. The silane-treated clay formed by surface-treating kaolin clay by means of these functional silanes characteristically contains low residual levels of the non-ionic surfactants. The functional silanes can be either vinyl or sulfur functional silanes. The silane treated clays are useful as fillers or extenders in rubber compositions, particularly those employing silicas and/or carbon blacks.
摘要:
A coarse particle kaolin clay is provided having an average Stokes equivalent particle diameter of about 4.5-6.0 microns, a BET surface area of about 8-11 m.sup.2 /g, and preferably having a median Malvern particle size of about 9.0-10.5 microns as determined by laser light-scattering measurement and a high aspect ratio preferably of about 12-14 as determined by Sphericity Model calculations. The coarse particle kaolin clay provides low viscosity build, good reinforcement properties and excellent surface finish qualities as a filler in thermoset composite materials, such as polyester molding compounds, and also provides excellent pigmenting properties in paints and industrial coatings. Preparation of the coarse particle clay involves blunging and degritting a crude kaolin clay, conducting three separate centrifugation steps with the desired product stream being, in sequence, the coarse underflow clay from the primary centrifuge, the coarse underflow from the secondary centrifuge, and then the fine overflow from the tertiary centrifuge, followed by magnetic separation, screening, chemical leaching, drying and milling to produce a kaolin clay product having the above-described physical properties and performance characteristics.