Calcium silicate sphere

Abstract

(i) The d50 median particle size is in the range of 1 to 35 μm, (ii) The oil absorption amount is in the range of 40 to 130 mL / 100 g, (iii) The sphericity coefficient (S 80 ) is about 0.80 or more, (iv) The BET surface area is 10 to 125 m 2 / g, and (v) The CaO% is 0.5 to 20% by weight of spherical calcium silicate. Spherical calcium silicate is (a) A step of continuously supplying a mineral acid and an alkali metal silicate to a loop reaction zone including a flow of a liquid medium, wherein at least a part of the mineral acid and the alkali metal silicate reacts to form a silica product in the liquid medium of the loop reaction zone; (b) A step of continuously recirculating the liquid medium through the loop reaction zone; (c) A step of continuously discharging a part of the liquid medium containing the silica product from the loop reaction zone; (d) A step of filtering and washing the liquid medium containing the silica product; (e) A step of mixing the filter cake of step (d) with calcium hydroxide; (f) A step of stirring the mixed filter cake and calcium hydroxide of step (e) for 10 minutes to 180 minutes (aging step); and (g) A step of drying the solution is produced by. Spherical calcium silicate can be used in dentifrice compositions, food mixtures, personal care applications, and liquid coatings.

Description

Technical Field

[0001] The present disclosure generally relates to novel spherical calcium silicate, as well as methods for its production and use.

Background Art

[0002] In the fields of food, feed, pharmaceuticals, and industrial applications, synthetic amorphous calcium silicate has been used for many years. Synthetic amorphous calcium silicate is produced by reacting a pre-prepared silica or silicate substantially free of sodium sulfate with a slurry of calcium hydroxide at a temperature above 60°C (U.S. Patent No. 1,574,363, U.S. Patent No. 4,557,916). This reaction results in the formation of calcium silicate particles with high absorption capacity, which are useful in the above-mentioned application fields.

[0003] U.S. Patent No. 2,204,113 describes a process for producing micronized calcium silicate, in which separate aqueous solutions of calcium halide and soluble silicate are simultaneously injected into different positions within a reaction vessel.

[0004] From U.S. Patent Application Publication No. 2012 / 0216719, coating compositions containing spheroid-shaped silica or silicate are known.

[0005] Also, calcium silicate is commonly used in personal care applications (U.S. Patent No. 7,163,669).

[0006] Also, calcium silicate is particularly known for dental compositions as disclosed in International Publication No. 2012 / 078136 pamphlet and / or International Publication No. 2018 / 073062 pamphlet, but does not jointly define main surface characteristics such as BET surface area, oil absorption characteristics, or the weight percentage of CaO present in the particles.

[0007] Silica particles with a reduced Relative Dentin Abrasion (RDA) value are disclosed and described in US Patent Application Publication No. 2020 / 0206107. Such silica particles have (i) a d50 median particle size of about 6 μm or more, (ii) a ratio of (d90 - d10) / d50 in the range of about 1.1 to about 2.4, (iii) an RDA at a loading of 20 wt% in the range of about 40 to about 200, and (iv) a sphericity coefficient (S 80 ) that can be about 0.9 or more. These silica particles have a spherical or morphological shape and can be manufactured using a continuous loop reactor process.

[0008] Therefore, it would be beneficial in oral care to provide a calcium silicate material that increases the soluble calcium level in saliva and promotes the formation of new hydroxyapatite on the dentin or enamel surface. The material can also help smaller silica particles designed for tubule occlusion to have a higher affinity for the dentin surface and a greater likelihood of remaining in the oral cavity after brushing. Since this silica has a smaller surface area than conventional calcium silicate products, it can also achieve mechanical cleaning of the tooth surface.

[0009] In coating applications, the calcium silicate material of the present invention can be used to improve the corrosion resistance of a metal substrate.

Prior Art Documents

Patent Documents

[0010]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

[0011] Summary of the Invention This summary is provided to introduce, in a simplified form, a selection of concepts that are further described in the detailed description below. This summary is not intended to identify the required features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

[0012] The spherical calcium silicate of the present invention that can be used is disclosed and described herein. According to one aspect of the present invention, such spherical calcium silicate has (i) a d50 median particle size in the range of 1 to 35 μm, (ii) an oil absorption in the range of 40 to 130 mL / 100 g, (iii) a sphericity coefficient (S 80 ) of about 0.80 or more, (iv) a BET surface area of 10 to 125 m 2 / g, and (v) a CaO% of 0.5 to 20% by weight.

[0013] These silica and / or silicate particles are spherical or have a morphology and can be produced using a continuous loop reactor process.

[0014] Also disclosed herein are toothpaste compositions, cosmetics, and coatings containing the spherical calcium silicate of the present invention, as well as methods of using and compositions of spherical calcium silicate.

[0015] The foregoing summary and the following detailed description are both provided by way of example and are merely descriptive. Accordingly, the above summary and the following detailed description should not be regarded as limiting. Further, features or variations may be provided in addition to those described herein. For example, certain aspects may be directed to various combinations and sub - combinations of the features described in the detailed description.

Brief Description of the Drawings

[0016]

Figure 1

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Figure 6

Modes for Carrying Out the Invention

[0017] Definitions To more clearly define the terms used in this specification, the following definitions are provided. Unless otherwise indicated, the following definitions are applicable to the present disclosure. If a term used in the present disclosure is not specifically defined herein, the definition from the IUPAC Compendium of Chemical Terminology, 2nd Ed (1997) may be applied, provided that it does not conflict with any other disclosure or definition applied herein and does not render any claim to which it is applied unclear or inoperative. Any definition or use provided by any document incorporated herein by reference shall be governed by the definition or use provided herein to the extent that they conflict.

[0018] In this specification, the features of the subject matter are described such that, in certain embodiments, combinations of different features may be envisioned. For all aspects and all features disclosed in this specification, all combinations that do not adversely affect the designs, compositions, processes, or methods described herein are contemplated and may be exchanged, regardless of whether an explicit description of a particular combination is provided. Thus, unless otherwise specified, any aspects or features disclosed herein may be combined to describe designs, compositions, processes, or methods of the invention that are consistent with the present disclosure.

[0019] All publications and patents mentioned in this specification are incorporated herein by reference for the purpose of describing and disclosing, for example, the structures and methodologies described in the publications that may be used in connection with the inventions described herein.

[0020] Detailed Description of the Invention Disclosed herein are (i) a d50 median particle size in the range of 1 to 35 μm, preferably 1 to 20 μm, most preferably 3 to 15 μm, (ii) an oil absorption in the range of 40 to 130 mL / 100 g, preferably 50 to 100 mL / 100 g, (iii) a sphericity coefficient (S 80) is about 0.80 or more, preferably more than 0.85, (iv) the BET specific surface area is 10 to 125 m 2 / g, preferably 30 to 80 m 2 / g, and (v) the CaO% is 0.5 to 20% by weight, preferably 3 to 15% by weight, which can be the spherical calcium silicate of the present invention.

[0021] Also disclosed and described herein are methods for producing these spherical silica and / or silicate particles, toothpaste compositions containing spherical particles, and treatment methods using spherical particles in toothpaste compositions, cosmetics, and coatings.

[0022] Spherical silicate particles In accordance with an aspect of the present invention, spherical silicate particles with improved capillary occlusion may have the following characteristics: (i) the d50 median particle size is in the range of 1 to 35 μm, (ii) the oil absorption is in the range of 40 to 130 mL / 100 g, (iii) the sphericity coefficient (S 80 ) is 0.80 or more, (iv) the BET specific surface area is 10 to 125 m 2 / g, and (v) the CaO% is 0.5 to 20% by weight. The silicate particles can have any combination of the following provided features or characteristics.

[0023] The spherical calcium silicate of the present invention may have a CTAB specific surface area of 5 to 80 m 2 / g, preferably 10 to 70 m 2 / g.

[0024] The spherical calcium silicate of the present invention may have a packing density of 0.32 to 0.96 g / ml, preferably 0.40 to 0.80 g / ml.

[0025] The spherical calcium silicate of the present invention may have a 5% pH of 8.0 to 12.0, preferably 8.5 to 11.0, more preferably 9.0 to 10.5.

[0026] The calcium silicate spheres of the present invention may have a Ca:Si weight ratio of 0.015 to 0.60, more preferably 0.04 to 0.30, and the amount of Ca reflects the same amount of CaO% of 0.5 to 20% by weight, preferably 3 to 15% by weight, as described above and in claim 1.

[0027] The calcium silicate spheres of the present invention can have a relatively low water absorption rate. For example, the water absorption rate can be in the range of about 55 to about 115 mL / 100 g, about 65 to about 100 mL / 100 g, or about 70 to about 90 mL / 100 g. Other suitable ranges of the water absorption rate will be readily apparent from the present disclosure.

[0028] The calcium silicate spheres of the present invention may be amorphous, synthetic, or both amorphous and synthetic. Further, the calcium silicate spheres of the present invention may include precipitated calcium silicate spheres.

[0029] The calcium silicate spheres of the present invention may have a petaloid structure (on the surface by electron microscope).

[0030] Process for producing calcium silicate sphere particles The calcium silicate spheres of the present invention can be produced by the following process of the present invention.

[0031] Generally, the process of the present invention comprises: (a) continuously supplying a mineral acid and an alkali metal silicate to a loop reaction zone containing a flow of a liquid medium, wherein at least a part of the mineral acid and the alkali metal silicate react to form a silica product (e.g., silica and / or silicate particles) in the liquid medium of the loop reaction zone; (b) continuously recirculating the liquid medium through the loop reaction zone; (c) continuously discharging a part of the liquid medium containing the silica product from the loop reaction zone; (d) filtering the liquid medium containing the silica product and washing the filter cake; (e) mixing the filter cake of step (d) with calcium hydroxide; (f) stirring the mixed filter cake and calcium hydroxide of step (e) for 10 minutes to 180 minutes, preferably 60 minutes to 120 minutes (aging step); and (g) drying the solution.

[0032] The spherical calcium silicate of the present invention disclosed herein is not limited to any particular synthetic procedure. However, in order to achieve the desired sphericity, the spherical calcium silicate of the present invention can be formed by utilizing a continuous loop reactor process for steps (a) to (c). This process and related reactor systems (which may include a continuous loop of one or more loop reactor pipes) are described in U.S. Patent No. 8,945,517 and U.S. Patent No. 8,609,068, which are hereby incorporated by reference in their entirety.

[0033] Typically, the supply positions of the mineral acid and the alkali metal silicate to the loop reaction zone are different, and the total supply rate of the acid and the silicate is proportional to and often equal to the discharge rate of the liquid medium containing the silica product. All or substantially all of the contents within the loop reaction zone are recirculated at a rate ranging from, for example, about 50% by volume per minute (the recirculation rate per minute is 1 / 2 of the total volume of the contents) to about 1000% by volume per minute (the recirculation rate per minute is 10 times the total volume of the contents), or from about 75% by volume per minute to about 500% by volume per minute.

[0034] The precipitation device can be configured as a recycle loop, where the reaction slurry can be circulated multiple times before being discharged (Figure 1). The loop can be composed of sections of fixed pipes joined to each other by sections of flexible hoses. A pump can be placed on one side of the loop to circulate the reaction mixture, and on the opposite side, a Silverson in-line mixer can be installed to provide additional shear to the system and also at a convenient location for adding acid. A static mixer heat exchanger can be installed between the pumps to provide means for controlling the temperature during the production of silica. The discharge pipe located behind the acid addition point can discharge the product according to the rate at which the silicate and acid are added. A backpressure valve can also be attached to the discharge pipe to enable the system to operate at temperatures above 100°C. The product discharge pipe can be directed to collect the product in a tank for additional modification (e.g., pH adjustment) or can be discharged directly into a rotary or press filter. Optionally, if the product is being prepared at a pH above 7.0, acid can be added to the product discharge line to avoid post-synthesis pH adjustment.

[0035] In the case of the present invention, the Silverson in-line mixer can be modified to provide a high level of mixing without imparting shear. This is achieved by removing the status screen from the Silverson mixer and operating the unit with only the backing plate and the normal mixer head. Additionally, the Silverson mixer can be run with a standard rotor / square hole high-shear stator to obtain smaller particle sizes. By varying the Silverson output, the particle size can be adjusted in either configuration.

[0036] In process step (d), filtration can be carried out by a filter press, a rotary vacuum filter, a belt filter, or a similar solid / liquid separation device. The filter cake can be washed to reduce salt residues, such as sodium sulfate.

[0037] The mixing of the filtration cake from step (d) with calcium hydroxide in step (e) can be carried out in a stirred vessel capable of maintaining a desired temperature of 30 to 100 °C. The calcium hydroxide can be a slurry containing 5 to 20% by solid content, more preferably 10 to 18% calcium hydroxide. The calcium hydroxide can be a slurry in water.

[0038] Stirring in process step (e) can be carried out at a temperature of 30 to 100 °C (aging step), more preferably 60 to 95 °C.

[0039] The drying (g) of calcium silicate can be carried out by a spray dryer or a flash dryer at a temperature sufficient to evaporate water from the solid content.

[0040] The spherical calcium silicate of the present invention can be used in dentifrice compositions, food mixtures, personal care applications, and liquid coatings.

[0041] Dentifrice composition The spherical calcium silicate of the present invention can be used in any suitable composition and for any suitable end use, such as in oral care, personal care, coatings, and the food field. In many cases, silica and / or silicate particles can be used for oral care applications such as dentifrice compositions.

[0042] In oral care, calcium can be used for remineralization by increasing the soluble calcium level in saliva and promoting the formation of new hydroxyapatite on the dentin or enamel surface. The material can also help that small silica particles designed for tubule occlusion have a higher affinity for the dentin surface and a higher likelihood of remaining in the oral cavity after brushing. Since this silica has a smaller surface area than conventional calcium silicate products, it can also achieve mechanical cleaning of the tooth surface.

[0043] The dentifrice composition may contain any suitable amount of the spherical calcium silicate of the present invention, such as about 0.5 to about 40% by weight, about 1 to about 35% by weight, about 3 to about 15% by weight, about 3 to about 10% by weight, etc. These weight percentages are based on the total weight of the dentifrice composition.

[0044] The dentifrice composition can be in any suitable form, such as a liquid, powder, or paste. In addition to silica and / or silicate particles, the dentifrice composition may contain other components or additives, non-limiting examples of which include humectants, solvents, binders, therapeutic agents, chelating agents, thickeners other than the spherical calcium silicate of the present invention, surfactants, abrasives other than the spherical calcium silicate of the present invention, sweeteners, colorants, flavoring agents, preservatives, etc., and any combinations thereof.

[0045] Humectants add stickiness or "mouthfeel" to the dentifrice and help prevent the dentifrice from drying out. Suitable humectants include polyethylene glycol (various different molecular weights), propylene glycol, glycerin (glycerol), erythritol, xylitol, sorbitol, mannitol, lactitol, and hydrolyzed hydrogenated starch, and mixtures thereof. In some formulations, the humectant is present in an amount of about 20 to about 50% by weight based on the weight of the dentifrice composition.

[0046] The solvent can be present in the dentifrice composition in any suitable loading amount and usually the solvent includes water. When used, water is preferably deionized, free of impurities, and can be present in the dentifrice in a loading amount of 5 to about 70% by weight, or about 5 to about 35% by weight based on the weight of the dentifrice composition.

[0047] Furthermore, the therapeutic agent can be used in the compositions of the present invention to achieve, for example, the prevention and treatment of dental caries, periodontal diseases, and temperature sensitivity. Suitable therapeutic agents include fluoride sources such as sodium fluoride, sodium monofluorophosphate, potassium monofluorophosphate, stannous fluoride, potassium fluoride, sodium fluorosilicate, ammonium fluorosilicate, etc.; condensed phosphates such as tetrasodium pyrophosphate, tetrapotassium pyrophosphate, disodium dihydrogen pyrophosphate, trisodium hydrogen pyrophosphate; tripolyphosphates, hexametaphosphates, trimetaphosphates, and pyrophosphates; antibacterial agents such as triclosan, bisguanides such as alexidine, chlorhexidine, and chlorhexidine gluconate; enzymes such as papain, bromelain, glucoamylase, amylase, dextranase, mutanase, lipase, pectinase, tannase, and protease; quaternary ammonium compounds such as benzalkonium chloride (BZK), benzethonium chloride (BZT), cetylpyridinium chloride (CPC), and domiphen bromide; metal salts such as zinc citrate, zinc chloride, and stannous fluoride; sanguinaria extracts and sanguinarine; volatile oils such as eucalyptol, menthol, thymol, and methyl salicylate; amine fluorides; peroxides, etc., but are not limited thereto. The therapeutic agent can be used in the dentifrice formulation alone or in combination at any therapeutically safe and effective level or dosage.

[0048] Thickeners are useful in dentifrice compositions for providing a gelatinous structure that stabilizes the dentifrice against phase separation. Suitable thickeners include silica thickeners; starch; starch glycerides; gums such as karaya gum (sterculia gum), tragacanth gum, gum arabic, gatti gum, acacia gum, xanthan gum, guar gum, and cellulose gum; magnesium aluminum silicate (Veegum); carrageenan; sodium alginate; agar; pectin; gelatin; cellulose compounds such as cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxymethyl cellulose, hydroxymethyl carboxypropyl cellulose, methyl cellulose, ethyl cellulose, and sulfated cellulose; (co)polymers of acrylic acid, natural and synthetic clays such as hectorite clay; and mixtures thereof. Typical levels of thickeners or binders are up to about 15% by weight of the dentifrice or dentifrice composition.

[0049] Examples of silica thickeners useful for use in dentifrice compositions include, without limitation, amorphous precipitated silica such as ZEODENT® 165 silica. Other non-limiting silica thickeners include ZEODENT® 153, 163 and / or 167, and ZEOFREE® 177 and / or 265 silica products, all available from Evonik Corporation.

[0050] Surfactants can be used in the dentifrice composition of the present invention to make the composition more aesthetically acceptable. The surfactant is preferably a cleaning material that imparts cleaning and foaming properties to the composition. Suitable surfactants include safe and effective amounts of anionic surfactants, cationic surfactants, nonionic surfactants, zwitterionic surfactants, amphoteric surfactants, and betaine surfactants, such as sodium lauryl sulfate, sodium dodecylbenzenesulfonate, alkali metal salts or ammonium salts of lauroyl sarcosinate, myristoyl sarcosinate, palmitoyl sarcosinate, stearoyl sarcosinate, and oleoyl sarcosinate, polyoxyethylene sorbitan monostearate, isostearate, and laurate, sodium laurylsulfacetate, N-lauroyl sarcosine, sodium salts, potassium salts, and ethanolamine salts of N-lauroyl, N-myristoyl, or N-palmitoyl sarcosine, polyethylene oxide condensates of alkylphenols, cocamidopropyl betaine, lauramidopropyl betaine, palmityl betaine, and the like. Sodium lauryl sulfate is a preferred surfactant. The surfactant is typically present in the composition of the present invention in an amount of about 0.1 to about 15% by weight, about 0.3 to about 5% by weight, or about 0.3 to about 2.5% by weight.

[0051] The disclosed spherical calcium silicate can be used alone as an abrasive in a dentifrice composition, or as an additive, or as a co-abrasive with other abrasive materials discussed herein or known in the art. Thus, any number of other conventional types of abrasive additives can be present within the dentifrice composition of the present invention. Other such abrasive particles include, for example, precipitated calcium carbonate (PCC), ground calcium carbonate (GCC), chalk, bentonite, dicalcium phosphate or its dihydrate form, silica gel (alone and in any structure), precipitated silica, amorphous precipitated silica (similarly, alone and in any structure), perlite, titanium dioxide, dicalcium phosphate, calcium pyrophosphate, alumina, hydrated alumina, calcined alumina, aluminum silicate, insoluble sodium metaphosphate, insoluble potassium metaphosphate, insoluble magnesium carbonate, zirconium silicate, particulate thermosetting resin, and other suitable abrasive materials. Such materials can be introduced into the dentifrice composition to adjust the abrasive properties of the target formulation.

[0052] A sweetening agent can be added to the dentifrice composition (e.g., toothpaste) to impart a pleasant taste to the product. Suitable sweetening agents include saccharin (as sodium saccharin, potassium saccharin, or calcium saccharin), cyclamate (as the sodium salt, potassium salt, or calcium salt), acesulfame-K, thaumatin, neohesperidin dihydrochalcone, ammoniated glycyrrhizin, dextrose, levulose, sucrose, mannose, and glucose.

[0053] A coloring agent can be added to improve the aesthetic appearance of the product. Suitable coloring agents include, but are not limited to, coloring agents approved by appropriate regulatory agencies such as the FDA and those described in the European Food and Drug Guidelines, pigments such as TiO2, and colors such as FD&C and D&C dyes.

[0054] A flavoring agent can also be added to the dentifrice composition. Suitable flavoring agents include, but are not limited to, wintergreen oil, peppermint oil, spearmint oil, sassafras oil, and clove oil, cinnamon, anethole, menthol, thymol, eugenol, eucalyptol, lemon, orange, and fruit notes, spice notes, and other flavor compounds such as those added. These flavoring agents generally include a mixture of aldehydes, ketones, esters, phenols, acids, and aliphatic, aromatic, and other alcohols.

[0055] To prevent the growth of bacteria, a preservative can also be added to the composition of the present invention. Suitable preservatives approved for use in oral compositions such as methylparaben, propylparaben, and sodium benzoate can be added in a safe and effective amount.

[0056] Other ingredients, such as desensitizing agents, healing agents, other caries preventives, chelating agents / sequestering agents, vitamins, amino acids, proteins, other anti-plaque / anti-calculus agents, opacifying agents, antibiotics, anti-enzymes, enzymes, pH control agents, oxidizing agents, antioxidants, etc. can be used in the dentifrice composition.

[0057] Method of Use Both the spherical calcium silicate of the present invention and the compositions disclosed herein can be used in treatment methods. For example, a method of reducing dental sensitivity in accordance with the present invention can include contacting any of the spherical calcium silicates (or any of the compositions) disclosed herein with the surface of a mammalian tooth. Accordingly, the spherical calcium silicate (or composition) can be applied or delivered to the surface of a mammalian tooth via brushing or any other suitable technique. Any suitable amount of silica and / or silicate particles (or composition) can be used for any suitable period of time.

[0058] In another aspect, a method of occluding dentinal tubules within the surface of a mammalian tooth that is consistent with the present invention may include contacting any of the calcium silicate spheres (or any of the compositions) disclosed herein with the surface of the mammalian tooth. As noted above, any suitable amount of calcium silicate spheres (or composition) can be applied or delivered to the surface of the mammalian tooth for any suitable period of time via brushing or any other suitable technique.

[0059] Sphericity coefficient (S 80 ) is determined as follows. Scanning electron microscope images were taken with a Zeiss Sigma instrument equipped with a field emission detector. The sample was dispersed in methanol and then the methanol slurry was dried on an aluminum sample holder. To minimize charging, the dried sample was sputter-coated with platinum and then imaged.

[0060] SEM images of the silica and / or silicate particle samples were magnified 250 to 2,000 times to represent the silica and / or silicate particle samples and imported into photo imaging software to trace the contour (two-dimensional) of each particle. Particles that are close to each other but not attached to each other must be considered separate particles for this analysis. The traced particles are then filled in with color and the image is imported into particle property evaluation software (e.g., IMAGE-PRO PLUS available from Media Cybernetics, Inc., Bethesda, Md.) capable of determining the perimeter and area of the particles. The sphericity of the particles can then be calculated according to the formula, sphericity = (perimeter) 2 ÷(4π×area), where the perimeter is the software-measured perimeter derived from the trace with the particle contour drawn, and the area is the software-measured area within the traced perimeter of the particle.

[0061] The sphericity is calculated for each particle that fits entirely within the SEM image. These values are then sorted by value, and the lowest 20% of these values are discarded. The remaining 80% of these values are averaged to obtain the sphericity coefficient (S 80 ). Additional information regarding sphericity can be found in U.S. Patent Nos. 8,945,517 and 8,609,068, which are incorporated herein by reference in their entirety.

[0062] The BET surface area disclosed herein was measured by a Micromeritics TriStar II 3020 V1.03 using the BET nitrogen adsorption method of Brunaur et al., J. Am. Chem. Soc., 60, 309 (1938). Such techniques are well known to those skilled in the art.

[0063] The CTAB surface area disclosed herein was determined by the absorption of CTAB (cetyltrimethylammonium bromide) on the silica surface, the excess was separated by centrifugation, and the amount was determined by titration with sodium lauryl sulfate using a surfactant electrode. Specifically, about 0.5 grams of silica and / or silicate particles were placed in a 250 mL beaker containing 100 mL of a CTAB solution (5.5 g / L), mixed on a magnetic stirrer plate for 1 hour, and then centrifuged at 10,000 RPM for 30 minutes. 1 mL of 10% Triton X-100 was added to 5 mL of the clear supernatant in a 100 mL beaker. The pH was adjusted to 3 - 3.5 with 0.1 N HCl, and the sample was titrated with 0.01 M sodium lauryl sulfate using a surfactant electrode (Brinkmann SUR1501-DL) to determine the end point.

[0064] The d50 median particle size refers to the particle size at which 50% of the sample has a smaller size and 50% of the sample has a larger size. The median particle size (d50), average particle size (average), and d95 were determined via a laser diffraction method using a Horiba LA 300 instrument. For the analysis, dry particles were loaded into the instrument.

[0065] For pour density and bulk density, a 20-gram sample was placed into a 250 mL graduated cylinder with a rubber flat bottom. The initial volume was recorded and used to calculate the pour density by dividing it by the weight of the sample used. The cylinder was then placed on a tap density machine and rotated at 60 RPM on a cam. The cam is designed to raise and lower the cylinder at a distance of 5.715 cm per second for typically 15 minutes until the sample volume becomes constant. This final volume was recorded and used to calculate the bulk density by dividing it by the weight of the sample used.

[0066] The oil absorption value was determined using linseed oil according to the rub-out method described in ASTM D281 (cc of oil absorbed per 100 g of particles). Generally, the higher the oil absorption level, the more porous the particles with a higher level of large pores, which can also be explained as a higher structure.

[0067] The water absorption value was determined using an absorption meter "C" torque rheometer manufactured by C.W. Brabender Instruments, Inc. Approximately 1 / 3 of the silica sample cup was transferred to the mixing chamber of the absorption meter and mixed at 150 RPM. Then, water was added at a rate of 6 mL / min, and the torque required to mix the powder was recorded. As the water is absorbed by the powder, the torque reaches its maximum when the powder changes from free-flowing to a paste. Then, the total amount of water added when the maximum torque was reached was standardized to the amount of water that can be absorbed by 100 g of the powder. Since the powder was used as it was (without pre-drying), the "moisture correction water AbC value" was calculated using the following formula with the free moisture value of the powder. [Number]

[0068] The absorption meter is commonly used to determine the oil number of carbon black according to methods B and C of ASTM D 2414 and ASTM D 3493.

[0069] The pH value (5% pH) disclosed in this specification was determined in an aqueous system containing 5% by weight of solids in deionized water using a pH meter.

[0070] The CaO% (calcium concentration) was determined by the following method. 2.0000 g of silica was moistened with a few drops of deionized water in a platinum crucible. 10 ml of perchloric acid (72%) and 10 ml of hydrofluoric acid (48 - 50%) were added, and the platinum dish was slowly heated on a stirring plate in a fume hood. When the platinum dish was heated, thick white smoke was generated. Then, the sides of the crucible were carefully rinsed with boric acid (4%) and heated until this also became smoke. After cooling, the contents of the crucible were transferred to a 250 ml volumetric flask, and the crucible was washed with deionized water to confirm that all the remaining contents had been quantitatively transferred. Then, the dish was rinsed with 5 ml of hydrochloric acid (36%), and the washing solution was also added to the volumetric flask. Approximately 200 ml of deionized water was added to the volumetric flask, and if the resulting solution was turbid, it was heated on a low-temperature hot plate until it became clear. After cooling, 2.50 ml of scandium internal standard solution was added, and the volumetric flask was filled to the mark with deionized water. Then, the concentration of metals in the solution was determined by ICP / OES.

[0071] The sulfate concentration was measured using a LECO SC832 series combustion analyzer, manufactured by LECO, St. Joseph, Michigan, USA. The sample was placed in a combustion boat and heated to approximately 1350 °C in an oxygen-rich environment. Carbon and sulfur were released as their respective oxides and measured by IR spectroscopy. The concentration of sulfur or carbon was determined by comparison with known standards.

Examples

[0072] The present invention will be further illustrated by the following examples, which should in no way be construed as limiting the scope of the present invention. After reading the description in this specification, various other aspects, modifications, and their equivalents may be suggested to those skilled in the art without departing from the spirit of the present invention or the scope of the appended claims.

[0073] Set-up of the continuous loop reactor: The precipitation device was configured with a recycle loop where the reaction slurry could be circulated multiple times before being discharged (Figure 1). The loop was composed of sections of fixed pipes joined to each other by sections of flexible hoses. The inner diameter of the piping / hoses was approximately 1.5 inches and the volume was approximately 45 L. A pump was placed on one side of the loop to circulate the reaction mixture, and on the opposite side, a Silverson in-line mixer was installed to provide additional shear to the system and also at a convenient location for adding acid. A static mixer heat exchanger was installed between the pumps to provide means for controlling the temperature during the production of silica. The discharge pipe located behind the acid addition point was capable of discharging the product depending on the rate at which the silicate and acid were added. A backpressure valve can also be attached to the discharge pipe to enable the system to operate at temperatures exceeding 100 °C. The product discharge pipe can be oriented to collect the product in a tank for additional modification (e.g., pH adjustment) or discharged directly into a rotary or press filter. Optionally, if the product is being prepared at a pH exceeding 7.0, acid can be added to the product discharge line to avoid post-synthesis pH adjustment.

[0074] In the case of the present invention, the Silverson in-line mixer can be modified to provide a high level of mixing without imparting shear. This was achieved by removing the status screen from the Silverson mixer and operating the unit with only the backing plate and the normal mixer head (Example D). Additionally, the Silverson mixer can be run with a standard rotor / square hole high shear stator to obtain smaller particle sizes (Example C). By varying the Silverson output, the particle size can be adjusted in either configuration.

[0075] Initial set-up Before introducing acid and silicate into the system, precipitated silica, sodium sulfate, sodium silicate, and water were added and recirculated at 180 L / min. This step was carried out to fill the recirculation loop with approximately the contents and concentrations of a typical batch to minimize the purge time, after which the desired product could be collected. It was also done to avoid the possibility of forming a gel inside the reactor, but subsequent experiments revealed that acid and silicate could be directly added to a loop filled with water without gelling or plugging the system.

[0076] Example 1: 1.5 kg of Zeodent® 103, 1.34 kg of sodium sulfate, 11.1 L of sodium silicate (3.32 MR, 19.5%), and 20 L of water were added to the recirculation loop and heated to 90 °C while recirculating at 180 L / min by a Silverson (with the stator removed and operating at 2320 Hz (1740 RPM) as the shear frequency (reference 145 patent application)). Sodium silicate (3.32 MR, 19.5%) and sulfuric acid (17.1%) were simultaneously added to the loop at a silicate rate of 1.7 L / min and an acid rate sufficient to maintain a pH of 7.5. The acid rate was adjusted as appropriate to maintain the pH. Acid and silicate were added for 40 minutes under these conditions to purge unnecessary silica from the system, after which the desired material was collected. After 40 minutes, the collection vessel was emptied and its contents discarded. Then, while maintaining the temperature at approximately 80 °C and stirring at 40 RPM, the silica product was collected in the vessel. After collecting the desired amount of product, the addition of acid and silicate was stopped and the contents of the loop were filtered to a conductivity of less than 1000 μS / cm.

[0077] Example 1A: 30 kg of silica wet cake from Example 1 (based on dry mass) and 120 L of water were mixed and stirred in a stainless-steel tank. To this, 8.7 L of a calcium hydroxide slurry having a specific gravity of 1.104 g / mL and a solids content of approximately 15.6% was added to the diluted silica slurry, and the mixture was stirred for 60 minutes. After 60 minutes, the entire solution was spray-dried to a target moisture of approximately 5%.

[0078] Example 1B: 30 kg of silica wet cake from Example 1 (based on dry mass) and 120 L of water were mixed and stirred in a stainless-steel tank. To this, 17.4 L of a calcium hydroxide slurry having a specific gravity of 1.104 g / mL and a solids content of approximately 15.6% was added to the diluted silica slurry, and the mixture was stirred for 60 minutes. After 60 minutes, the entire solution was spray-dried to a target moisture of approximately 5%.

[0079] Example 1C: 30 kg of silica wet cake from Example 1 (based on dry mass) and 120 L of water were mixed and stirred in a stainless-steel tank. To this, 26.1 L of a calcium hydroxide slurry having a specific gravity of 1.104 g / mL and a solids content of approximately 15.6% was added to the diluted silica slurry, and the mixture was stirred for 60 minutes. After 60 minutes, the entire solution was spray-dried to a target moisture of approximately 5%.

[0080] Example 2: 1.5 kg of Zeodent® 103, 1.34 kg of sodium sulfate, 11.1 L of sodium silicate (3.32 MR, 19.5%), and 20 L of water were added to the recirculation loop and heated to 70 °C while recirculating at 180 L / min by a Silverson (with the stator removed, operating at 30 Hz (1740 RPM) with a shear frequency of 5,000 (same reference as above)). Sodium silicate (3.32 MR, 19.5%) and sulfuric acid (17.1%) were simultaneously added to the loop at a silicate rate of 1.7 L / min and an acid rate sufficient to maintain a pH of 7.5. The acid rate was adjusted as appropriate to maintain the pH. The acid and silicate were added for 40 minutes under these conditions to purge unwanted silica from the system, and then the desired material was collected. After 40 minutes, the collection container was emptied and its contents discarded. The silica product was then collected in the container while stirring at 40 RPM while maintaining the temperature at approximately 80 °C. After collecting the desired amount of product, the addition of acid and silicate was stopped and the contents of the loop were circulated.

[0081] Example 2A: 30 kg of silica wet cake (based on dry mass) from Example 2 and 120 L of water were mixed and stirred in a stainless - steel tank. To this, 3.7 L of a calcium hydroxide slurry having a specific gravity of 1.120 g / mL and approximately 18.2% solids was added to the diluted silica slurry, and the mixture was stirred for 60 minutes. After 60 minutes, the entire solution was spray - dried to a target moisture of approximately 5%.

[0082] Example 2B: 30 kg of silica wet cake (based on dry mass) from Example 2 and 120 L of water were mixed and stirred in a stainless - steel tank. To this, 7.4 L of a calcium hydroxide slurry having a specific gravity of 1.120 g / mL and approximately 18.2% solids was added to the diluted silica slurry, and the mixture was stirred for 60 minutes. After 60 minutes, the entire solution was spray - dried to a target moisture of approximately 5%.

[0083] Example 2C: 30 kg of silica wet cake (based on dry mass) from Example 2 and 120 L of water were mixed and stirred in a stainless-steel tank. To this, 14.9 L of a calcium hydroxide slurry having a specific gravity of 1.120 g / mL and a solids content of approximately 18.2% was added to the diluted silica slurry, and the mixture was stirred for 60 minutes. After 60 minutes, the entire solution was spray-dried to a target moisture of approximately 5%.

[0084] Example 3: 1.5 kg of Zeodent® 103, 1.34 kg of sodium sulfate, 11.1 L of sodium silicate (3.32 MR, 19.5%), and 20 L of water were added to a recirculation loop and heated to 90 °C while recirculating at 180 L / min by a Silverson (with the stator removed and operating at 2320 Hz (1740 RPM) with a shear frequency of 5,000 (reference 145 patent application)). Sodium silicate (3.32 MR, 19.5%) and sulfuric acid (17.1%) were simultaneously added to the loop at a silicate rate of 1.7 L / min and an acid rate sufficient to maintain a pH of 7.5. The acid rate was adjusted as appropriate to maintain the pH as needed. The acid and silicate were added for 40 minutes under these conditions, and the unwanted silica was purged from the system before collecting the desired material. After 40 minutes, the collection vessel was emptied and its contents were discarded. Then, while maintaining the temperature at approximately 80 °C and stirring at 40 RPM, the silica product was collected in the vessel. After collecting the desired amount of product, the addition of acid and silicate was stopped and the contents of the loop were filtered to a conductivity of less than 1000 μS / cm.

[0085] Example 3A: The filter cake from Example 3 was diluted to 10% solids and pumped into a 400 - gallon batch reactor and stirred at 60 RPM. This slurry contained approximately 45 kg of silica on a dry mass basis. A slurry of 11.1 L of calcium hydroxide with a specific gravity of 1.054 g / mL and approximately 18.2% solids was added to the silica slurry, and the reactor was heated to 95°C and then aged for 2 hours. After the 2 - hour aging time, the batch contents were spray - dried to a target moisture of 5%.

[0086] Chemical and physical data are shown in Tables 1 and 2.

[0087] [Table 1]

[0088] [Table 2]

[0089] Example 4: Comparative Example 4A: 1.5 kg of Zeodent® 103, 1.34 kg of sodium sulfate, 11.1 L of sodium silicate (3.32 MR, 19.5%), and 20 L of water were added to the recirculation loop. The stator was installed inside the Silverson and heated to 83 °C while recirculating at 180 L / min. Sodium silicate (3.32 MR, 13.3%) and sulfuric acid (11.4%) were simultaneously added to the loop at a silicate rate of 6.4 L / min and an acid rate sufficient to maintain a pH of 7.5. The acid rate was adjusted as appropriate to maintain the pH. The acid and silicate were added for 40 minutes under these conditions to purge the unwanted silica from the system and then the desired material was collected. After 40 minutes, the collection vessel was emptied and its contents discarded. The silica product was then collected in the vessel while stirring at 40 RPM while maintaining the temperature at approximately 80 °C. After collecting the desired amount of product, the addition of acid and silicate was stopped and the contents of the loop were filtered to a conductivity of less than 1000 μS / cm and then spray dried to a target moisture of 5%.

[0090] Comparative Example 4B: 200 g of Comparative Example 4A was slurried in water at a concentration of 10% and heated to 60 °C while overhead stirring at 300 RPM (sufficient to prevent the silica from settling). 64 ml of an aqueous calcium hydroxide slurry solution (17.5% solids, 1.12 g / ml) was added to the silica slurry and the reaction mixture was aged for 45 minutes while stirring at 300 RPM. After 45 minutes, the reaction mixture was filtered and oven dried at 105 °C overnight.

[0091] Comparative Example 4C: 200 g of Comparative Example 4A was slurried in water at a concentration of 10% and heated to 60 °C while overhead stirring at 300 RPM (sufficient to prevent the silica from settling). 86 ml of an aqueous calcium hydroxide slurry solution (17.5% solids, 1.12 g / ml) was added to the silica slurry and the reaction mixture was aged for 45 minutes while stirring at 300 RPM. After 45 minutes, the reaction mixture was filtered and oven dried at 105 °C overnight.

[0092] Comparative Example 4D: 200 g of Comparative Example 4A was slurried in water at a concentration of 10% and heated to 60 °C with overhead stirring at 300 RPM (sufficient to prevent silica from settling). 110 ml of an aqueous calcium hydroxide slurry solution (solid content 17.5%, 1.12 g / ml) was added to the silica slurry, and the reaction mixture was aged for 45 minutes while stirring at 300 RPM. After 45 minutes, the reaction mixture was filtered and oven-dried at 105 °C overnight.

[0093] Example 5: Comparative Example 5A: 1.5 kg of Zeodent® 103, 1.34 kg of sodium sulfate, 11.1 L of sodium silicate (3.32 MR, 19.5%), and 20 L of water were added to a recirculation loop and heated to 90 °C while recirculating at 180 L / min by Silverson (with the stator removed and operating at 2320 Hz (1740 RPM) as the shear frequency (Reference 145 patent application)). Sodium silicate (3.32 MR, 19.5%) and sulfuric acid (17.1%) were simultaneously added to the loop at a silicate rate of 1.7 L / min and an acid rate sufficient to maintain a pH of 7.5. The acid rate was adjusted as appropriate to maintain the pH. The acid and silicate were added for 40 minutes under these conditions, and the unwanted silica was purged from the system before collecting the desired material. After 40 minutes, the collection vessel was emptied and its contents were discarded. Then, while maintaining the temperature at about 80 °C and stirring at 40 RPM, the silica product was collected in the vessel. After collecting the desired amount of product, the addition of acid and silicate was stopped, the contents of the loop were filtered to a conductivity of less than 1000 μS / cm, and then spray-dried to a target moisture of 5%.

[0094] Example 5B: 200 g of Comparative Example 5A was slurried in water at a concentration of 10% and heated to 60 °C with overhead stirring at 300 RPM (sufficient to prevent silica from settling). 64 ml of an aqueous calcium hydroxide slurry solution (solid content 17.5%, 1.12 g / ml) was added to the silica slurry, and the reaction mixture was aged for 2.5 hours while stirring at 300 RPM. After 45 minutes, the reaction mixture was filtered and oven-dried at 105 °C overnight.

[0095] Example 5C: 200 g of Comparative Example 5A was slurried in water at a concentration of 10% and heated to 60 °C with overhead stirring at 300 RPM (sufficient to prevent silica from settling). 110 ml of an aqueous calcium hydroxide slurry solution (solid content 17.5%, 1.12 g / ml) was added to the silica slurry, and the reaction mixture was aged for 2.5 hours while stirring at 300 RPM. After 45 minutes, the reaction mixture was filtered and oven-dried at 105 °C overnight.

[0096] The chemical and physical data are shown in Table 3.

[0097] [Table 3]

[0098] Example 6: 1.5 kg of Zeodent® 103, 1.34 kg of sodium sulfate, 11.1 L of sodium silicate (3.32 MR, 19.5%), and 20 L of water were added to a recirculation loop. The stator was installed inside a Silverson and heated to 83 °C while recirculating at 180 L / min. Sodium silicate (3.32 MR, 13.3%) and sulfuric acid (11.4%) were simultaneously added to the loop at a silicate rate of 6.4 L / min and an acid rate sufficient to maintain a pH of 7.5. The acid rate was adjusted as appropriate to maintain the pH. The acid and silicate were added for 40 minutes under these conditions to purge unwanted silica from the system, after which the desired material was collected. After 40 minutes, the collection vessel was emptied and its contents discarded. The silica product was then collected in the vessel while stirring at 40 RPM while maintaining the temperature at approximately 80 °C. After collecting the desired amount of product, the addition of acid and silicate was stopped and the contents of the loop were filtered to a conductivity of less than 1000 μS / cm.

[0099] Example 6A: 30 kg of silica wet cake from Example 6 (based on dry mass) and 120 L of water were mixed and stirred in a stainless-steel tank. A slurry of calcium hydroxide containing 1.5 kg of calcium hydroxide (dry mass) was added to the diluted silica slurry, and the mixture was stirred for 60 minutes at ambient temperature. After 60 minutes, the entire solution was spray-dried to a target moisture of approximately 5%.

[0100] Example 6B: 30 kg of silica wet cake from Example 6 (based on dry mass) and 120 L of water were mixed and stirred in a stainless-steel tank. A slurry of calcium hydroxide containing 4.5 kg of calcium hydroxide (dry mass) was added to the diluted silica slurry, and the mixture was stirred for 60 minutes at ambient temperature. After 60 minutes, the entire solution was spray-dried to a target moisture of approximately 5%.

[0101] Example 7: 1.5 kg of Zeodent® 103, 1.34 kg of sodium sulfate, 11.1 L of sodium silicate (3.32 MR, 19.5%), and 20 L of water were added to the recirculation loop, the stator was installed inside the Silverson, and it was heated to 70 °C while recirculating at 180 L / min. Sodium silicate (3.32 MR, 13.3%) and sulfuric acid (11.4%) were simultaneously added to the loop at a silicate rate of 6.4 L / min and an acid rate sufficient to maintain a pH of 7.5. As necessary, the acid rate was adjusted as appropriate to maintain the pH. The acid and silicate were added for 40 minutes under these conditions to purge the unwanted silica from the system and then the desired material was collected. After 40 minutes elapsed, the collection container was emptied and its contents were discarded. Then, while maintaining the temperature at about 80 °C and stirring at 40 RPM, the silica product was collected in the container. After collecting the desired amount of product, the addition of the acid and silicate was stopped and the contents of the loop were filtered to a conductivity of less than 1000 μS / cm.

[0102] Example 7A: 30 kg of silica wet cake from Example 6 (based on dry mass) and 120 L of water were mixed and stirred in a stainless-steel tank. To this, a slurry of calcium hydroxide containing 4.5 kg of calcium hydroxide (dry mass) was added to the diluted silica slurry and the mixture was stirred for 60 minutes at ambient temperature. After 60 minutes, the entire solution was spray-dried to a target moisture of about 5%.

[0103] Example 7B: 30 kg of silica wet cake from Example 6 (based on dry mass) and 120 L of water were mixed and stirred in a stainless-steel tank. To this, a slurry of calcium hydroxide containing 6.0 kg of calcium hydroxide (dry mass) was added to the diluted silica slurry and the mixture was stirred for 60 minutes at ambient temperature. After 60 minutes, the entire solution was spray-dried to a target moisture of about 5%.

[0104] Example 8: 1.5 kg of Zeodent® 103, 1.34 kg of sodium sulfate, 11.1 L of sodium silicate (3.32 MR, 19.5%), and 20 L of water were added to a recirculation loop, the stator was installed inside a Silverson, and heated to 83 °C while recirculating at 180 L / min. Sodium silicate (3.32 MR, 13.3%) and sulfuric acid (11.4%) were simultaneously added to the loop at a silicate rate of 6.4 L / min and an acid rate sufficient to maintain a pH of 7.5. As necessary, the acid rate was adjusted as appropriate to maintain the pH. The acid and silicate were added for 40 minutes under these conditions to purge unwanted silica from the system and then the desired material was collected. After 40 minutes, the collection vessel was emptied and its contents discarded. Then, while maintaining the temperature at about 80 °C and stirring at 40 RPM, the silica product was collected in the vessel. After collecting the desired amount of product, the addition of acid and silicate was stopped and the contents of the loop were filtered to a conductivity of less than 1000 μS / cm.

[0105] Example 8A: The filter cake from Example 8 was diluted to 10% solids and pumped into a 400 gallon batch reactor and stirred at 60 RPM. This slurry contained approximately 45 kg of silica on a dry mass basis. A slurry of 39.1 L of calcium hydroxide with a specific gravity of 1.104 g / mL and approximately 15.6% solids was added to the silica slurry, the reactor was heated to 95 °C and then aged for 2 hours. After 2 hours of aging time, the batch contents were spray dried to a target moisture of 5%.

[0106] Chemical and physical data are shown in Tables 4 and 5.

[0107] [Table 4]

[0108] [Table 5]

[0109] The SEM images of FIGS. 2-6 show the spherical particle morphology of calcium silicate. Looking at the surface of the calcium silicate material of the present invention, a petaloid structure is sometimes observed. This petaloid structure is described in column 5, line 56 of U.S. Patent No. 6,287,530 as a structure like a rose flower that can be observed on the surface by an electron microscope. Without being bound by a particular theory, it is believed that the petaloid structure may result in a higher level of available calcium that may be beneficial for uses in the oral care, cosmetic, coating, and food fields.

[0110] Example 9: Toothpaste formulation In oral care, calcium can be used for remineralization by increasing the soluble calcium level in saliva and promoting the formation of new hydroxyapatite on the dentin or enamel surface. The material can also help small silica particles designed for tubule occlusion to have a higher affinity for the dentin surface and a higher likelihood of remaining in the oral cavity after brushing. Since this silica has a smaller surface area than conventional calcium silicate products, it can also achieve mechanical cleaning of the tooth surface. PCR and RDA tests were conducted at the Indiana University School of Dentistry.

[0111] The toothpaste formulations and data are shown in Table 6 below.

[0112] Relative Dentin Abrasion (RDA) The RDA values of the dentifrice compositions of Examples DC1-DC14 containing the silica of the present invention were determined according to the method described by Hefferen, Journal of Dental Res., July-August 1976, 55(4), pp. 563-573 and as described in Wason U.S. Patent Nos. 4,340,583, 4,420,312, and 4,421,527, the contents of which are incorporated herein by reference in their entirety.

[0113] Pellicle cleaning rate ("PCR") The cleaning property of the dentifrice composition was typically expressed by converting it into a Pellicle cleaning rate ("PCR") value. The PCR test measures the ability of the dentifrice composition to remove the pellicle film from teeth under fixed brushing conditions. The PCR test is described in "In Vitro Removal of Stain with Dentifrice" G.K. Stookey, et al., J. Dental Res., 61, 12 - 36 - 9, 1982. The results of both PCR and RDA vary depending on the nature and concentration of the components of the dentifrice composition. The values of PCR and RDA are unitless.

[0114] [Table 6]

[0115] Example 10: Food Mixture Calcium silicate is also used as an anti - caking aid and a flow - promoting aid in food applications. Calcium silicate is typically added to spices and / or food mixtures at levels within the range of 1 - 2% in order to improve the flow and handling properties during food preparation. Studies were carried out to demonstrate the effectiveness of these materials as anti - caking and flow - promoting aids in table salt. Table salt was treated with each prototype calcium silicate at 1.5% (double - checked) and thoroughly mixed. The salt samples were then exposed to moisture (chamber or added water) and then tested for fluidity. It was found that the salt control without calcium silicate had significantly worse flow properties than the salt samples containing the calcium silicate of the present invention. The data is shown in Table 7 below.

[0116] The angle of repose and compressibility tests were performed with a Hosokawa Micron Corporation, Summit, NJ, Powder Tester model PT - S according to the instructions attached to the apparatus. Wet salt and wet salt containing 2 wt% of the calcium silicate of the present invention were evaluated.

[0117] The angle of repose test was performed and a low slope was observed for the salts containing calcium silicate. The lower value of the angle of repose for the samples is due to a decrease in interparticle aggregation that indicates an improvement in fluidity.

[0118] The value of the compressibility was determined by the ratio of the aerated bulk density to the packed bulk density. The lower value of the compressibility was due to the calcium silicate-containing salt samples, which reduced interparticle cohesiveness and allowed the salt to more efficiently fill a given volume. All samples containing calcium silicate of the present invention were found to result in a lower value of compressibility and an improvement in fluidity.

[0119]

Table 7

[0120] Example 11: Personal care applications Also, calcium silicate is commonly used in personal care applications (U.S. Patent No. 7,163,669). Since calcium silicate has a spherical shape, it can be used for the feel of the skin while also providing the ability to neutralize acidic odor substances. Previous studies have shown that the ability to absorb acidic odors derived from sebum is an important function in deodorants and antiperspirants. The acid neutralization ability of the samples was evaluated by titration with HCl. The test calcium silicate was slurried at 5 wt% and mixed at 300 RPM using a ZetaProbe acoustic zeta potential instrument manufactured by Colloidal Dynamics. The instrument was equipped with an automatic pipette system that allowed for the accurate addition of the liquid solution. 1.0 M HCl was added at 0.25 ml / min until the pH stabilized at 4.0. The volume of acid required to lower the pH to 4.0 is directly related to the neutralization ability of the calcium silicate prototype. The acid neutralization ability is shown in Table 8 below.

[0121]

Table 8

[0122] Example 12: Preparation of Liquid Coating Preparation of Solvent-Derived Formulations (Examples 12A - 12B) Formulation Examples 12A and 12B were prepared by mixing the components together for each component according to the order listed in Table 9 at ambient room temperature. Next, 2.5 mm ceramic grinding media was added to the container (the mass of the media was 1:1 with respect to the total formulation). The formulation was ground for 2 hours with a LAU disperser to achieve a Hegman score of 6 (25.4 microns). The grinding media was separated using a 226 micron mesh filter.

[0123] [Table 9]

[0124] Preparation of Aqueous Formulations (Examples 12C - 12D) Formulation Examples 12C and 12D were similarly prepared by mixing the components together for each component (excluding the epoxy resin and thickener) in the order listed in Table 10 at ambient room temperature. This was ground for at least 30 minutes with a Cowl blade using a Dispermat to achieve a Hegman score of 6 (25.4 microns). Next, the epoxy resin and thickener were added and mixed for another 10 minutes. The Formulation B pack was prepared by mixing the curing agent and solvent before application of the coating.

[0125] [Table 10]

[0126] Coating Application The solvent-based coating was applied to a 4×6 cold rolled steel panel with a wet film thickness of 3 mils using a drawdown bar and flash dried overnight in ventilation. The samples were fired at 250 °C for 30 minutes.

[0127] The waterborne coating was applied to 4×6 cold-rolled steel panels at a wet film thickness of 6 mils using a drawdown bar and cured for 7 days under ambient conditions.

[0128] Testing of the cured film Both the solventborne coating and the waterborne coating were evaluated in a similar manner. The panels were scribed using a box cutter in accordance with ASTM D1654. The exposed metal edges and the backside of the panels were covered with vinyl tape.

[0129] The solventborne samples were subjected to a 300-hour salt spray corrosion test, while the waterborne samples were subjected to a 1000-hour salt spray corrosion test. After reaching 300 hours (for the solventborne) and 1000 hours (for the waterborne samples), the panels were removed, the surfaces were wiped and dried. The panels were rubbed using a metal spatula, and eight scribed creep measurements were uniformly obtained along the scribes in accordance with ASTM D1654. The average scribed creep was the average of the eight measurements.

[0130] Table 11 shows the results of the scribed creep measurements.

[0131]

Table 11

[0132] Examples of the present invention (12B and 12D) exhibit equivalent corrosion protection performance compared to current commercially available benchmark anticorrosive pigments (12A and 12C).

[0133] In addition, the examples of the present invention have environmental benefits for calcium silicate compared to the use of conventional additive phosphates.

Claims

1. (i) d50 median particle size is in the range of 1 to 35 μm, (ii) Oil absorption capacity is within the range of 40 to 130 mL / 100 g. (iii) Coefficient of sphericity (S ８０ ) is approximately 0.80 or higher. (iv) BET surface area of ​​10 to 125 m ２ / g In spherical calcium silicate, (v) Spherical calcium silicate characterized by having a CaO content of 0.5 to 20% by weight.

2. CTAB surface area 5-80 m ２ The spherical calcium silicate according to claim 1, wherein the amount is / g.

3. The spherical calcium silicate according to claim 1, wherein the packing density is 0.32 to 0.96 g / mL.

4. The spherical calcium silicate according to claim 1, wherein the 5% pH is 8.0 to 12.

0.

5. The spherical calcium silicate according to claim 1, wherein the water absorption rate is in the range of 55 to 115 mL / 100 g.

6. The spherical calcium silicate according to claim 1, wherein the weight ratio of Ca:Si is 0.015 to 0.

600.

7. (a) A step of continuously supplying a mineral acid and an alkali metal silicate to a loop reaction zone including a flow of a liquid medium, wherein at least a portion of the mineral acid and the alkali metal silicate react to form a silica product in the liquid medium of the loop reaction zone; (b) A step of continuously recirculating the liquid medium through the loop reaction zone; (c) A step of continuously discharging a portion of the liquid medium containing the silica product from the loop reaction zone; (d) A step of filtering and washing the liquid medium containing the silica product; (e) A step of mixing the filtered cake from step (d) with calcium hydroxide; (f) A step of stirring the mixed filtration cake and calcium hydroxide from step (e) for 10 to 180 minutes (aging step); and (g) drying the solution A method for producing spherical calcium silicate according to any one of claims 1 to 6, comprising:

8. The method for producing spherical calcium silicate according to claim 7, wherein the supply positions of the mineral acid and the alkali metal silicate to the loop reaction zone are different.

9. The method for producing spherical calcium silicate according to claim 7, wherein the total supply rate of the acid and silicate in step (a) is proportional to or equal to the discharge rate of the liquid medium containing the silica product (c).

10. The method for producing spherical calcium silicate according to claim 7, wherein in step (b), all or substantial contents of the loop reaction zone are recirculated at a rate ranging from 50% by volume / min to 1000% by volume / min.

11. Use of spherical calcium silicate according to any one of claims 1 to 6 in toothpaste compositions, food mixtures, personal care applications, and liquid coatings.

12. A toothpaste composition containing spherical calcium silicate according to any one of claims 1 to 6.

13. A coating composition comprising spherical calcium silicate according to any one of claims 1 to 6.

14. A food composition comprising spherical calcium silicate according to any one of claims 1 to 6.

15. A cosmetic composition comprising spherical calcium silicate according to any one of claims 1 to 6.

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