Precipitated silica and method thereof

Abstract

Precipitated silica and method thereof The present disclosure provides a granular material having an average primary particle size of 80 nm to 140 nm and a BET surface area of ​​40 m 2 / g and an oil absorption of 160 to 250 cc / 100 g. The silica of the present invention can be prepared by the steps of: (a) dispersing colloidal seed particles having a primary particle size in the range of 40 to 100 nm, preferably 50 to 80 nm, in water; (b) adding an electrolyte at a concentration of 2.5 to 4.0 wt. % based on the total mass of the colloidal seed particles added in step (a); (c) heating the suspension to 65 to 100°C, preferably 85 to 95°C; (d) adding acid and silicate over a period of 60 to 180 minutes while maintaining the pH between 7.5 and 10, preferably between 8 and 9; and (d) adding 1.8 to 5.0% electrolyte based on the starting water amount during the acid and silicate addition (c). (e) stopping the addition of silicate; (f) adding acid until a pH of 3 to 6 is reached; (g) filtering, drying, and optionally grinding; It is produced by a method comprising: The precipitated silica of the present invention is used in cosmetics, anti-caking free / flow, food, carrier applications, dentifrices and mouthwashes.

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE This disclosure relates generally to precipitated silica and methods of making and using same.

[0002] Background technology Porous precipitated silica is typically produced by the reaction of an alkali silicate solution, such as sodium silicate, with a mineral acid. Commercially, sulfuric acid is primarily used, but other acids, such as hydrochloric acid, can also be used. The acid and sodium silicate solution are simultaneously added to water with stirring. Precipitated silica results when silica precipitates from this dispersion through a neutralization reaction and the formation of a by-product sodium salt (sodium sulfate). Precipitated silica consists of aggregates (secondary particles) of primary (or final) colloidal silica particles. The primary particles are mostly spherical and typically have diameters ranging from 5 to 50 nm. The primary particles in the aggregates are covalently bonded to each other through the formation of siloxane bonds. The aggregates are three-dimensional clusters of these primary particles. The aggregates have diameters up to 500 nm. The aggregates are not chemically linked into a bulk gel network during the preparation process. The aggregates themselves can physically link to larger agglomerates up to 100 μm in diameter by forming hydrogen bonds between silanol groups on their surfaces before grinding. The median aggregate size is approximately 20-50 μm in diameter (before grinding). The porosity and surface area of ​​these precipitated silica particles are a function of the size of the primary particles and how they aggregate and clump together. Pores are formed by the spaces between the primary particles and the aggregates. Typical surface areas of commercially available precipitated silicas range from 5-800 m 2 / g. They are sold as powders. The tamped density, a measure of the weight of these porous powders, ranges from 50 to 500 kg / m 3 They have a high absorption capacity of about 30-320g / 100g.

[0003] US Patent No. 4,708,859 specifies a range of 20 to 120 m 2 / g CTAB, 250~500ml / 100g oil adsorption and 8000nm 2reported silica with a projected area of ​​over 1000 nm.

[0004] U.S. Patent No. 8,597,425 reports that porous precipitated silicas with a primary particle size of 10 to 80 nm are useful for applications including rubber and tires, battery separators, antiblocking agents, matting agents for inks and paints, carriers for agricultural products and feeds, coating materials, printing inks, fire extinguisher powders, plastics, non-impact printing applications, paper pulp, or articles in the personal care field.

[0005] J. Soc. Cosmet. Chem. August 1978, 29, 497-521 reports that precipitated silicas having a primary particle size of 12-51 nm are useful in cosmetic applications, including toothpaste.

[0006] The commercial product SIPERNAT® 22, useful in food and feed applications as a carrier and anti-caking free-flow additive, is reported to have a primary particle size of 18 nm (Degussa literature No. 64, Physiological Behavior of highly dispersed Oxides of Silicon, Aluminum and Titanium 1978, pp. 26-27).

[0007] U.S. Patent No. 6,946,119 describes silica particles having a median diameter of 1 to 100 micrometers that support surface deposits, including activated precipitated amorphous silica, and silica particles having a median diameter of 1 to 50 micrometers. 2 The present invention discloses a precipitated silica product comprising silica microparticles containing a material present in an amount effective to provide a BET specific surface area of ​​1 / g. The precipitated silica is used in oral care applications.

[0008] U.S. Pat. No. 7,255,852 discloses a precipitated silica containing silica product particles having a porous surface, the silica particles having a surface roughness of 8 m as measured by mercury intrusion. 2 / g less than 500A diameter, approximately 20m 2 / g and a cumulative surface area for all pores having a cetylpyridinium chloride compatibility percentage (%CPC) of greater than 55%. The precipitated silica is used in oral care applications.

[0009] U.S. Patent No. 7,438,895 discloses an abrasive precipitated silica material having a coating of precipitated silica thereon, said coating of precipitated silica being denser than the material to which it is applied, said coated precipitated silica material having a median particle size of between 5.5 and 8 microns, a maximum of about 2.4 microns. 2 / g of pore area for pores having a diameter greater than 500 Å, and a cetylpyridinium chloride compatibility percentage of at least 90% after aging the material at 140°F for 7 days.

[0010] US Patent Application Publication No. 20080160053 describes a method for producing an abrasive silica material, the method comprising the following sequential steps: reacting a first amount of silicate with a first amount of acid, optionally in the presence of at least one electrolyte present in an amount of 5-25% w / w relative to the dry weight of the first amount of said silicate, under high shear mixing conditions to form a first silica material; and reacting a second amount of silicate with a second amount of acid, optionally in the presence of at least one electrolyte present in an amount of 5-25% w / w relative to the dry weight of the second amount of said silicate, in the presence of the first silica material, to form a dense phase coating on the surface of the first silica material, thereby forming a silica-coated silica material; the at least one electrolyte is present during either or both of the steps, and the second step is optionally carried out under high shear mixing conditions.

[0011] U.S. Patent No. 10,328,002 specifies a thickness of about 0.1 to about 9 m. 2 / g range of BET surface area; about 35 to about 55 lb / ft 3and a total mercury intrusion pore volume in the range of about 0.4 to about 1.2 cc / g; and a stannous compatibility in the range of about 70 to about 99%, wherein the abrasive comprises large pores of about 1000 angstroms or greater in size and lacks small pores of about 500 to about 1000 angstroms in size.

[0012] International Publication No. 2018114280 Brochure: Approximately 0.1 to 7m 2 / g range of BET surface area; about 35 to about 55 lb / ft 3 Einlehner abrasion values ​​ranging from about 8 to about 25 mg loss / 100,000 revolutions; total mercury intrusion pore volumes ranging from about 0.7 to about 1.2 cc / g; and stannous compatibility ranging from about 70 to about 99%.

[0013] U.S. Patent Application Publication No. 20190374448 discloses a dentifrice composition comprising a binder; a surfactant; and silica particles, the silica particles having a d50 median particle size ranging from about 4 to about 25 μm; 2 / g; and a total mercury intrusion pore volume in the range of about 0.2 to about 1.5 cc / g.

[0014] WO 2019238777 describes a particle size distribution having (i) a d50 median particle size in the range of about 8 to about 20 μm; (ii) a sphericity coefficient (S80) of about 0.9 or greater; (iii) a sphericity coefficient (S80) of about 0.1 to about 8 μm; 2 / g; (iv) a total mercury intrusion pore volume in the range of about 0.35 to about 0.8 cc / g; and (v) a loss on ignition (LOI) in the range of about 3 to about 7 wt.%.

[0015] European Patent No. 22160705.4 describes a method for producing granular materials with an average primary particle size of more than 80 nm and a particle size of 10 to 40 m. 2 / g BET surface area, a total mercury intrusion of 0.75-2.00 cc / g, and an oil absorption of 60-120 cc / 100g are described.

[0016] U.S. Patent No. 4,708,859 describes precipitated silicas characterized by high oil absorption of more than 300 cc / 100 g with lower and higher BET surface areas. This U.S. application does not provide compatibility and viscosity data for silicas used in toothpaste formulations.

[0017] The ability of precipitated silica to provide ingredient compatibility while providing the correct balance of cleaning and abrasion is important in toothpaste formulations. None of the prior art addresses the issues of compatibility with other ingredients, such as CPC and BAC, as well as lack of flavor compatibility, while simultaneously achieving PCR (80-110) and RDA (100-220) values ​​within the normal range.

[0018] Summary of the Invention The inventors of the present invention have now found that silicas with a high primary particle size can provide high compatibility with CPC, BAC and / or flavors in oral care applications, while providing acceptable viscosity build compared to conventional thickening silicas.

[0019] The subject of the present invention is therefore a material having an average primary particle size of more than 80 nm, preferably more than 100 nm, more preferably more than 115 nm, most preferably between 115 nm and 130 nm, and a particle size of 40 nm or less. 2 / g, preferably less than 35m 2 / g, more preferably less than 30m 2 / g, most preferably less than 15m 2 / g~30m 2 / g and an oil absorption of greater than 160 cc / 100g, preferably greater than 175 cc / 100g, more preferably greater than 200 cc / 100g, and most preferably between 200 cc / 100g and 250 cc / 100g.

[0020] The subject of the present invention is also (a) dispersing colloidal seed particles having a primary particle size in the range of 40 to 100 nm in water; (b) adding an electrolyte at a concentration of 2.5 to 4.0 wt. % based on the total mass of the colloidal seed particles added in step (a); (c) heating the suspension to 65-100°C; (d) adding acid and silicate over a period of 60 to 180 minutes while maintaining the pH between 7.5 and 10; (e) stopping the addition of silicate; (f) adding acid until a pH of 3 to 6 is reached; (g) filtering, drying, and optionally grinding; The method includes:

[0021] A further subject of the present invention is the use of the silica of the invention in cosmetics, anti-caking free / flow, food, carrier applications, dentifrices and mouthwashes.

[0022] A further subject of the present invention is oral care comprising the silica of the present invention. [Brief explanation of the drawings]

[0023] [Figure 1] FIG. 1 shows BAC titration. [Figure 2] FIG. 1 is a diagram showing an SEM image of Comparative Example 1. [Figure 3] FIG. 10 is a diagram showing an SEM image of Example 3 of the present invention. [Figure 4] FIG. 10 is a view showing an SEM image of Example 9 of the present invention.

[0024] MODE FOR CARRYING OUT THE INVENTION The precipitated silica of the present invention has an average primary particle size of more than 80 nm, preferably more than 100 nm, more preferably more than 115 nm, and most preferably between 115 nm and 130 nm, 2 / g, preferably less than 35m 2 / g, more preferably less than 30m 2 / g, most preferably less than 15m 2 / g~30m 2 / g and an oil absorption of greater than 160 cc / 100g, preferably greater than 175 cc / 100g, more preferably greater than 200 cc / 100g, and most preferably between 200 cc / 100g and 250 cc / 100g.

[0025] The precipitated silica according to the invention has an average primary particle size (a) of 80 nm≦(a)≦140 nm, preferably 110 nm≦(a)≦140 nm, and a BET surface area (b) of 40 m 2 / g, preferably less than 27m 2 / g or less, and the oil absorption (c) is 160 cc / 100 g ≦ (c) ≦ 250 cc / 100 g,

[0026] The precipitated silica according to the present invention may have a total mercury intrusion of from 2.5 cc / g to 5.3 cc / g, preferably from 3.0 to 5.3 cc / g, more preferably from 4.0 to 5.3 cc / g.

[0027] The precipitated silica according to the present invention is 40 ml 2 / g, preferably less than 35m 2 / g, more preferably less than 30m 2 / g of CTAB surface area.

[0028] The precipitated silica according to the invention has a density of 0.32 g / cm 3 less than 0.11 to 0.24 g / cm 3 The packing density may be

[0029] The precipitated silica according to the present invention has an average primary particle size of 100 to 125 nm and a particle size of 15 to 30 nm. 2 / g BET surface area, a total mercury intrusion of 2.5 to 5.3 cc / g, and an oil absorption of 200 to 250 cc / 100g.

[0030] The precipitated silica according to the present invention has an average primary particle size of more than 80 nm and a particle size of 10 to 40 nm. 2 / g BET surface area, a total mercury intrusion of 2.5 to 5.3 cc / g, and an oil absorption of 175 to 250 cc / 100g.

[0031] The precipitated silica according to the present invention has an average primary particle size of more than 100 nm, 10 to 26 m 2 / g BET surface area, a total mercury intrusion of 2.5 to 5.3 cc / g, and an oil absorption of 175 to 250 cc / 100g.

[0032] The precipitated silica according to the present invention has an average primary particle size of more than 100 nm, 10 to 23 m 2 / g BET surface area, a total mercury intrusion of 2.5 to 5.3 cc / g, and an oil absorption of 175 to 250 cc / 100g.

[0033] The precipitated silica according to the present invention has an average primary particle size of more than 80 nm and a particle size of 10 to 30 m 2 / g BET surface area, a total mercury intrusion of 2.5 to 5.3 cc / g, and an oil absorption of 175 to 250 cc / 100g.

[0034] The precipitated silica according to the present invention has an average primary particle size of more than 100 nm, 10 to 23 m 2 / g BET surface area, a total mercury intrusion of 2.5 to 5.3 cc / g, and an oil absorption of 175 to 250 cc / 100g.

[0035] The precipitated silica according to the present invention has an average primary particle size of 120 to 135 nm and a particle size of 10 to 20 m 2 / g BET surface area, a total mercury intrusion of 2.5 to 5.3 cc / g, and an oil absorption of 175 to 250 cc / 100g.

[0036] The precipitated silica according to the present invention has an average primary particle size of more than 100 nm and a particle size of 10 to 30 m 2 / g BET surface area, a total mercury intrusion of 2.5 to 5.3 cc / g, and an oil absorption of 175 to 250 cc / 100g.

[0037] The precipitated silica according to the present invention has an average primary particle size of 120 to 135 nm and a particle size of 10 to 20 m 2 / g BET surface area, a total mercury intrusion of 2.5 to 5.3 cc / g, and an oil absorption of 175 to 250 cc / 100g.

[0038] The precipitated silica according to the present invention has an average primary particle size (a) of 85 nm≦(a)≦100 nm and a particle size of 10 to 35 nm 2 / g BET surface area, a total mercury intrusion of 2.5 to 5.3 cc / g, and an oil absorption of 170 to 250 cc / 100g.

[0039] The method according to the invention comprises at least the following steps: (a) dispersing colloidal seed particles having a primary particle size in the range of 40 to 100 nm, preferably 50 to 80 nm, in water; (b) adding an electrolyte at a concentration of 2.5 to 4.0 wt. % based on the total mass of the colloidal seed particles added in step (a); (c) heating the suspension to 65 to 100°C, preferably 85 to 95°C; (d) adding acid and silicate over a period of 60 to 180 minutes while maintaining the pH between 7.5 and 10, preferably between 8 and 9; (e) stopping the addition of silicate; (f) adding acid until a pH of 3 to 6 is reached; (g) filtering, drying, and optionally grinding; Includes.

[0040] The filtration in step (g) can be carried out using a filter press, a rotary vacuum filter, a belt filter, or the like.

[0041] The drying in step (g) can be carried out in a spray dryer, flash dryer, or the like.

[0042] The milling in step (g) may be carried out in an impact mill such as a Raymond mill or an air jet mill.

[0043] The colloidal seed particles in step (a) can be 40-100 nm, such as Nexsil from Nyacol Nano Technologies, Inc.; AmSol from Applied Material Solutions, Inc.; Levasil from Nouryon; Snowtex from Nissan Chemical; and the like.

[0044] The dispersion of step (a) may be carried out in a baffled reactor with sufficient agitation to keep the particles dispersed.

[0045] The temperature range for step (a) may be 20-95°C, preferably 40-95°C, preferably 60-85°C, more preferably 70-80°C.

[0046] The colloidal seed particles in step (a) may be used in an amount of 0.15 to 5 wt. % based on the total amount added in step (a). The colloidal silica may represent 5 to 10% of the total silica product produced in process steps (a) through (g).

[0047] The silicate rate in step (d) can be 0.5-2.2% of the total amount of silicate added / min of the total amount of silicate added.

[0048] The alkali metal silicate in step (d) may preferably be an alkaline earth silicate or an alkali metal silicate, more preferably sodium silicate.

[0049] The acid in steps (d) and (f) may preferably be sulfuric acid.

[0050] The duration of step (d) may be between 60 and 180 minutes, preferably between 90 and 120 minutes.

[0051] During step (d), additional electrolyte may be added in an amount of 1.8 to 5.0% based on the starting water amount.

[0052] The electrolyte in step (b) may be an alkali metal salt, preferably a sodium or potassium salt such as a sulfate or chloride.

[0053] The precipitated silica of the present invention can be produced by the process of the present invention.

[0054] The precipitated silica of the present invention can be used in cosmetics, anti-caking free / flow, food, carrier applications, dentifrices and mouthwashes.

[0055] Oral care compositions comprising the precipitated silica of the present invention.

[0056] The oral care composition of the present invention has an average primary particle size of more than 80 nm and an average primary particle size of 10 to 40 nm. 2 / g, a total mercury intrusion of 0.75 to 2.00 cc / g, and an oil absorption of 60 to 120 cc / 100g.

[0057] The oral care composition of the present invention contains 5 ml 2 The secondary silica may include a BET surface area of ​​less than 1 / g.

[0058] The precipitated silica of the present invention has improved compatibility with cetylpyridinium chloride (CPC), benzalkonium chloride (BAC) and flavors while providing acceptable rheology in oral care applications.

[0059] Average primary particle size by SEM Images were taken at 50,000x magnification using scanning electron microscopy. Images were sputtered with platinum, and care was taken to ensure that the sputtering did not cause texture on the particle surface, as this could be mistaken for primary structure. Images must represent the entire sample and contain a minimum of 30 particles. Primary particles were then measured. If particles were not perfectly round, the smallest diameter across each particle was used. Particles at the edge of the image, which could not be fully observed, should not be used. Mean and median values ​​were then calculated based on the data set.

[0060] FIG. 2 shows an SEM image of Comparative Example 1.

[0061] 3 and 4 show SEM images of Examples 3 and 9 of the present invention.

[0062] brightness Silica samples were pressed into smooth-surfaced pellets and analyzed using a Technidyne Brightmeter S-5 / BC. This instrument has dual-beam optics where the sample is illuminated at a 45° angle and the reflected light is viewed at 0°. This complies with TAPPI test methods T452 and T646, as well as ASTM standard D985. The powder material is pressed into approximately 1 cm pellets with sufficient pressure to give a smooth, free-standing, and shiny pellet surface.

[0063] moisture Moisture content was determined by heating the silica for 2 hours at 105° C. Moisture content is the weight loss (%) of the undried silica.

[0064] BET surface area The BET surface area of ​​the silica of the present invention was determined using a Micromeritics TriStar 3020 instrument by the BET nitrogen adsorption method of Brunaur et al., J. Am. Chem. Soc., 60, 309 (1938), which is known in the field of particulate materials such as silica and silicate materials.

[0065] Oil absorption amount Oil absorption values ​​were determined using linseed oil according to the rub-out method described in ASTM D281 (cc of oil absorbed per 100 g of particles). Generally, higher oil absorption levels indicate particles with higher structure, while lower values ​​typically indicate particles with lower structure.

[0066] Total mercury injection Mercury intrusion or total pore volume (Hg) was measured by mercury porosimetry using a Micromeritics AutoPore IV 9520 (or Micromeritics AutoPore V 9620) instrument. Pore diameter was calculated by Washburn's equation using a contact angle theta (θ) equal to 130° and a surface tension gamma equal to 484 dynes / cm. Mercury was forced into the particle voids as a function of pressure, and the volume of mercury intruded per gram of sample at each pressure setting was calculated. The total pore volume expressed herein represents the cumulative volume of mercury intruded at pressures from vacuum to 60,000 psi. The volume increment (cm) at each pressure setting was calculated as 3 The pressure (p / g) was plotted against the pore radius or diameter corresponding to the increment in pressure setting. The peak of the intrusion volume vs. pore radius or diameter curve corresponds to the mode of the pore size distribution and identifies the most common pore size in the sample. Specifically, the sample size was adjusted to achieve 25-90% stem volume in a powder penetrometer with a 5 mL bulb and approximately 1.1 mL stem volume. The sample was evacuated to a pressure of 50 μm Hg and held for 5 minutes. The mercury filled the pores from 4.0 to 60,000 psi with a 10-second equilibration time at each data collection point. The total pore volume listed above is derived from the intraparticle porosity resulting from the pore structure within individual particles, as well as the interparticle porosity formed from the interstitial spaces between packed particles under pressure.

[0067] CTAB surface area The CTAB surface area disclosed herein was determined by absorption of CTAB (cetyltrimethylammonium bromide) on a silica surface; the excess was separated by centrifugation, and the amount was determined by titration with sodium lauryl sulfate using a surfactant electrode. Specifically, approximately 0.5 grams of silica particles were placed in a 250 mL beaker containing 100 mL of CTAB solution (5.5 g / L), mixed on an electric stir 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 the 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 endpoint.

[0068] particle size The particle size of the silica of the present invention was measured through the angle of scattered laser light using a HORIBA Laser Scattering Dry Particle Size Distribution Analyzer LA-960.

[0069] Moisture-corrected water AbC value Water absorption values ​​were determined using an Absorption Meter "C" torque rheometer manufactured by CW Brabender Instruments, Inc. Approximately one-third of the silica sample cup was transferred to the mixing chamber of the Absorption Meter and mixed at 150 RPM. Water was then added at a rate of 6 mL / min, and the torque required to mix the powder was recorded. As water was absorbed by the powder, the torque reached a maximum when the powder changed from free-flowing to a paste. The total amount of water added when the maximum torque was reached was then normalized to the amount of water that could be absorbed by 100 g of powder. Because the powder was used as is (without prior drying), the free moisture value of the powder was used to calculate the "moisture-corrected water AbC value" according to the following formula:

number

[0070] 5wt% pH The 5% pH was measured by weighing out 5.0 g of sample to the nearest 0.1 g and transferring the weighed sample to a 250 mL beaker. 95 mL of DI water was added and the sample was stirred for 5 minutes. The pH was then measured with a pH meter while stirring the sample.

[0071] Packed and bulk densities Packed density and bulk density were measured by placing 20.0 g of sample into a 250 mL graduated cylinder with a flat rubber bottom. The initial volume was recorded and used to calculate bulk density by dividing by the weight of the sample used. The cylinder was then placed on a tap density machine and rotated on a cam at a specific RPM. The cam was designed to raise and lower the cylinder at a distance of 5.715 cm per second, typically for 15 minutes, until the sample volume was constant. This final volume was recorded and used to calculate packed density by dividing by the weight of the sample used.

[0072] Example Comparative Example 1: 4000 mL of water and 60.0 g of NexSil 125-40 (80 nm colloidal silica, 40% by volume) were added to an 8 L reaction vessel and stirred at 350 rpm at a temperature of 98 °C. Approximately 5 mL of 50% sodium hydroxide was added to adjust the pH of the solution to 10.0. Sodium silicate (3.3 MR 19.5%) was then added at 12 mL / min, followed by sulfuric acid (17.1%) at a rate sufficient to maintain a pH of 9.80-9.95. After 150 min, the silicate flow was stopped, and sulfuric acid was added at 2.0 mL / min until a pH of 9.4 was reached. Once pH 9.4 was reached, the batch was filtered, washed with 4 L of deionized water, and dried overnight at 125 °C.

[0073] The analysis results are shown in Table 1. [Table 1]

[0074] Comparative Example 2: 4000 mL of water and 60.0 g of NexSil 125-40 (80 nm colloidal silica, 40% by volume) were added to an 8 L reaction vessel and stirred at 350 rpm at a temperature of 98 °C. Approximately 5 mL of 50% sodium hydroxide was added to adjust the pH of the solution to 10.0. Sodium silicate (3.3 MR 19.5%) was then added at 3 mL / min, followed by sulfuric acid (17.1%) at a rate sufficient to maintain a pH of 9.80-9.95. After 600 min, the silicate flow was stopped, and sulfuric acid was added at 2.0 mL / min until a pH of 9.4 was reached. Once pH 9.4 was reached, the batch was filtered, washed with 4 L of deionized water, and dried overnight at 125 °C.

[0075] The analytical results are shown in Table 2. [Table 2]

[0076] Comparative Example 3: 4000 mL of water and 60.0 g of NexSil 125-40 (80 nm colloidal silica, 40% by volume) were added to an 8 L reaction vessel and stirred at 350 rpm at a temperature of 98 °C. Approximately 5 mL of 50% sodium hydroxide was added to adjust the pH of the solution to 10.0. Water and sodium silicate (3.3 MR 19.5%) were then added at 6 mL / min and 6 mL / min, respectively. Sulfuric acid (17.1%) was added at a rate sufficient to maintain a pH of 9.80-9.95. After 256 min, the silicate flow was stopped, and sulfuric acid was added at 2.0 mL / min until a pH of 5.7 was reached. Once pH 5.7 was reached, the batch was filtered, washed with 4 L of deionized water, and dried overnight at 125 °C.

[0077] The analytical results are shown in Table 3. [Table 3]

[0078] Example 1 according to the present invention: 5508 mL of water, 100.0 g of NexSil 125-40 (80 nm colloidal silica, 40% by volume), and 192.5 g of sodium sulfate were added to an 8 L reaction vessel and stirred at 350 rpm at a temperature of 95 °C. Sodium silicate (3.3 MR 19.5%) was added at 6 mL / min, followed by sulfuric acid (17.1%) at a rate sufficient to maintain a pH of 9.5-9.9. After 180 min, the silicate flow was stopped, and sulfuric acid was added at 2.0 mL / min until a pH of 5.5 was reached. Once pH 5.5 was reached, the batch was filtered, washed with 4 L of deionized water, and dried overnight at 125 °C.

[0079] The analytical results are shown in Table 4. [Table 4]

[0080] Comparative Examples 4-5 and Examples 2-3 according to the invention: 5508 mL of water, 100.0 g of NexSil 125-40 (80 nm colloidal silica, 40% by volume), and sodium sulfate (see Table 5) were added to an 8 L reaction vessel and stirred at 350 rpm at a temperature of 95 °C. Sodium silicate (2.5 MR 20.0%) was added at 6 mL / min, and sulfuric acid (17.1%) was added at a rate sufficient to maintain a pH of 9.5-9.9. After 120 min, the silicate flow was stopped, and sulfuric acid was added at 2.0 mL / min until a pH of 5.5 was reached. Once pH 5.5 was reached, the batch was filtered, washed with 4 L of deionized water, and dried overnight at 125 °C. [Table 5]

[0081] The analytical results are shown in Table 6. [Table 6]

[0082] Examples 4 to 6 according to the present invention: 5000 mL of water, NexSil 125-40 (80 nm colloidal silica, 40% by volume—see Table 7), and 200 g of sodium sulfate were added to an 8 L reaction vessel and stirred at 350 rpm at a temperature of 95 °C. Sodium silicate (2.5 MR 20.0%) was added at 6 mL / min, and sulfuric acid (17.1%) was added at a rate sufficient to maintain a pH of 9.5-9.9. After 120 minutes, the silicate flow was stopped, and sulfuric acid was added at 2.0 mL / min until a pH of 5.5 was reached. Once pH 5.5 was reached, the batch was filtered, washed with 4 L of deionized water, and dried overnight at 125 °C. [Table 7]

[0083] The analytical results are shown in Table 8. [Table 8]

[0084] Examples 7 to 9 according to the present invention: Water, Silbond VPS XK-NF 60 (60 nm colloidal silica, 20.7% solids), and sodium sulfate (see Table 9) were added to an 8 L reaction vessel and stirred at 350 rpm at a temperature of 95 °C. Sodium silicate (2.5 MR 20.0%) was added at 12 mL / min, and sulfuric acid (17.1%) was added at a rate sufficient to maintain a pH of 8.4-8.7. After the time specified in Table 9, the silicate flow was stopped, and sulfuric acid was added at 2.0 mL / min until a pH of 5.5 was reached. Once pH 5.5 was reached, the batch was filtered, washed with 4 L of deionized water, and dried overnight at 125 °C. [Table 9]

[0085] The analytical results are listed in Table 10. The chemical and physical properties of ZEODENT® 165 and 153 are also listed in the same table. [Table 10]

[0086] According to the present invention, the desired compatibility can only be achieved by decreasing the BET SA and increasing the primary particle size along with the oil absorption range. It is likely not technically possible to provide a high oil absorption silica with a very low BET SA without increasing the primary particle size of the silica above 80 nm, so very high oil absorption values ​​would not provide the desired compatibility. BET SA and oil absorption values ​​are related and typically run parallel to each other; as one increases, the other also increases. Conventional synthesis techniques cannot separate these parameters to this extent.

[0087] In accordance with the present invention, the method involves (1) a solution of colloidal silica particles of the correct size (preferably 45-85 nm), (2) adding sodium sulfate and water to the solution of colloidal silica primary particles, and (3) carefully adding sodium silicate and sulfuric acid under appropriate conditions to grow the primary particles to greater than 80 nm. This primary particle growth reduces the BET SA and strengthens the primary aggregates to provide structural integrity to the particles and allow for sufficient viscosity buildup in toothpaste. An embodiment of the present invention produces primary aggregates of approximately 189,000-480,000 nm. 2 This level of aggregate strengthening can be measured by the average projected area of ​​the aggregates, such that the average projected area of ​​the aggregates is in the range of .gtoreq.1.

[0088] Example 10: BAC BAC titration: Zeta potential titrations were performed to determine the silica capacity of a given quaternary ammonium compound. For the titration, a 5 wt. % suspension of the desired silica was made by taking the desired amount of dry silica and diluting it to 160 g with deionized water. To approximate the desired 5 wt. % (8 g) silica in the 160 g suspension, the amount of as-received silica used was adjusted to account for the free moisture (loss on drying) and sodium sulfate present. The suspension was magnetically stirred at 500 rpm for 10 minutes to fully wet the silica, and then the suspension was adjusted to approximately pH 8.5 with either 0.5 M NaOH or 0.5 M HCl to aid in consistency of initial surface chemistry and more direct comparison.

[0089] Compared to classic toothpaste thickener silicas of similar oil absorption (Zeodent 153 and Zeodent 165) or higher oil absorption (Sipernat 50), the inventive silicas of Examples 7 and 9 required significantly less BAC (benzalkonium chloride) to exceed the "0" saturation point (Table 11, Figure 1). This would indicate a more favorable compatibility with cationic surfactants, despite their higher oil absorption and viscosity-building ability. This is due to the significant reduction in surface area brought about by the aggregation of larger primary particle sizes.

[0090] The BAC compatibility of Zeodent 153, Zeodent 165, SIPERNAT® 50 and two further silicas of the invention (3 and 5) in addition to Examples 7 and 9 according to the invention is shown in Table 11 below. [Table 11]

[0091] Example 11: Flavor Method: 500 mg of silica was placed in a headspace vial. 10 μl of flavor (lime oil, lot MKCF9356 flavor matrix) was added, and the vial was allowed to equilibrate overnight. The sample was incubated at 60°C for 60 minutes with gentle shaking, after which the headspace was sampled. 1 mL of headspace was analyzed in a GC / MS equipped with a Stabilwax column (0.25 mm x 60 m) over a temperature range of 40°C to 230°C with a column flow rate of 1.606 mL / min and a temperature gradient of 6°C / min (HS sampling: 1 ml of headspace was sampled into a gas-tight syringe at 65°C). Peak areas were normalized to the peak intensity of ZEODENT® 165.

[0092] The results are shown in Table 12. [Table 12]

[0093] The high pore volume silica of the present invention was incorporated into a standard toothpaste formulation to determine its performance during viscosity build-up in the toothpaste (Table 13). [Table 13]

[0094] They were compared to standard ZEODENT® 153 and the viscosity was measured over a 9 week period, with the results shown in Table 14. [Table 14]

[0095] Example 12: Free-flow food applications Loose bulk density The sample was poured through a funnel into a pre-tared 100 ml graduated cylinder until the cylinder overflowed. Excess sample was gently scraped off, and the weight of the cylinder / sample was determined. The density was then calculated by dividing the sample weight by its volume. Samples with increased loose bulk density values ​​typically exhibit improved flow characteristics, as the particles are "less sticky" and can pack more efficiently into a given space.

[0096] Pressure / heat / moisture solidification Pressure, heat, and moisture caking is a test used to determine the tendency of a powder to aggregate and form a clump (or cake) when exposed to pressure, heat, and / or moisture from either processing, packaging, shipping, or storage. A 5.0 g sample was loaded into an aluminum tray and subjected to predetermined conditions. The resulting cake was then transferred to a 12-mesh sieve and shaken for 1 minute. The remaining cake was then weighed and recorded as a percentage of the original 5.0 g sample.

[0097] Flodex Liquidity Index The Flodex is an instrument designed to evaluate the flow of powders through an orifice, such as the conditions experienced when a silo is emptied. The orifice size in the instrument is gradually reduced until the powder no longer flows out. The smaller the orifice size, the better the powder will flow. The Flodex powder flow tester was manufactured by Teledyne Hansen (Chatsworth, CA).

[0098] This test was conducted to evaluate the effectiveness of the silicas of the present invention in delaying caking and how they affect the flow properties of these model systems. Importantly, it was possible to maintain at least comparable performance to a standard anti-caking free-flow agent (Sipernat® 22S). However, it was observed that the examples of the present invention performed very well in salt and sweet whey systems to prevent caking, similar to Sipernat® 22S. In both food systems, the maximum allowable loading (2%) allowed in foods was used. It was found that even lower loadings of conditioning agent could be used (Tables 15+16). [Table 15] [Table 16]

Claims

1. The average primary particle size (a) is 80 nm≦(a)≦140 nm, and the BET surface area (b) is 40 m ２ / g and an oil absorption (c) of 160 cc / 100 g≦(c)≦250 cc / 100 g.

2. The BET surface area (b) is 8≦(b)≦35 m ２ 2. The precipitated silica of claim 1, wherein the SiO 2 content is 1 / g.

3. 40m ２ / g, preferably less than 35m ２ / g, more preferably less than 30m ２ 2. The precipitated silica of claim 1 having a CTAB surface area of ​​less than 1 / g.

4. 0.32 g / cm ３ less than 0.11 to 0.24 g / cm ３ 3. The precipitated silica of claim 1, having a packing density of

5. Average primary particle size of 100-125 nm, 15-30 nm ２ 2. The precipitated silica of claim 1 having a BET surface area of ​​1.0 to 1.5 cc / 100 g, a total mercury intrusion of 2.5 to 5.3 cc / 100 g, and an oil absorption of 200 to 250 cc / 100 g.

6. Average primary particle size (a) of 110 nm≦(a)≦140 nm, 10 to 40 nm ２ 2. The precipitated silica of claim 1 having a BET surface area of ​​1.0 to 1.5 cc / 100 g, a total mercury intrusion of 2.5 to 5.3 cc / 100 g, and an oil absorption of 175 to 250 cc / 100 g.

7. Average primary particle size (a) of 110 nm≦(a)≦140 nm, 10 to 26 nm ２ 2. The precipitated silica of claim 1 having a BET surface area of ​​1.0 to 1.5 cc / 100 g, a total mercury intrusion of 2.5 to 5.3 cc / 100 g, and an oil absorption of 175 to 250 cc / 100 g.

8. Average primary particle size (a) of 85 nm ≦ (a) ≦ 100 nm, 10 to 35 nm ２ 2. The precipitated silica of claim 1, having a BET surface area of ​​1.0 to 1.5 cc / 100 g, a total mercury intrusion of 2.5 to 5.3 cc / 100 g, and an oil absorption of 170 to 250 cc / 100 g.

9. At least the following steps: (a) dispersing colloidal seed particles having a primary particle size in the range of 40 to 100 nm, preferably 50 to 80 nm, in water; (b) adding an electrolyte at a concentration of 2.5 to 4.0 wt. % based on the total mass of the colloidal seed particles added in step (a); (c) heating the suspension to 65-100°C, preferably 85-95°C; (d) adding acid and silicate over a period of 60 to 180 minutes while maintaining the pH between 7.5 and 10, preferably between 8 and 9; (e) stopping the addition of silicate; (f) adding acid until a pH of 3-6 is reached; (g) filtering, drying, and optionally grinding; 1. A precipitated silica obtained by following a process comprising: The average primary particle size (a) is 80 nm≦(a)≦140 nm, and the BET surface area (b) is 40 m ２ / g and an oil absorption (c) of 250 cc / 100 g ≥ (c) ≥ 160 cc / 100 g.

10. the temperature range of step (a) is 40 to 95°C, preferably 60 to 85°C, more preferably 70 to 80°C; 10. A method for producing the precipitated silica of claim 9.

11. 10. The method for producing precipitated silica according to claim 9, wherein the colloidal seed particles in step (a) are used in an amount of 0.15 to 5% by weight based on the total amount added in step (a).

12. 10. The method of claim 9, wherein the rate of silicate in step (d) is 0.5-2.2% of the total amount of silicate added / total amount of silicate added.

13. 10. A process for producing precipitated silica according to claim 9, wherein said alkali metal silicate of step (d) is an alkaline earth silicate or an alkali metal silicate, more preferably sodium silicate, and said acid of steps (d) and (f) is preferably sulfuric acid.

14. 10. The method for producing precipitated silica according to claim 9, wherein the electrolyte in step (b) is an alkali metal salt, preferably a sodium or potassium salt such as sulfate, chloride, etc.

15. 10. Use of the precipitated silica according to claim 1 in cosmetics, anti-caking free / flow, food, carrier applications, dentifrices and mouthwashes.

16. An oral care composition comprising the precipitated silica of claim 1.

17. Average primary particle size of more than 80 nm, 10-40 nm ２ 17. The oral care composition of claim 16, comprising a secondary precipitated silica having a BET surface area of ​​0.75 to 2.00 cc / 100g, a total mercury intrusion of 0.75 to 2.00 cc / 100g, and an oil absorption of 60 to 120 cc / 100g.

18. 5m ２ 17. The oral care composition of claim 16, comprising a secondary silica having a BET surface area of ​​less than 1 / g.

Images