CN118765261A

CN118765261A - Precipitated silica and method thereof

Info

Publication number: CN118765261A
Application number: CN202280084500.0A
Authority: CN
Inventors: K·W·加利斯; F·A·辛克莱; T·W·纳斯维拉; M·S·达尔斯洛; E·G·伦德奎斯特
Original assignee: Evonik Operations GmbH
Current assignee: Evonik Operations GmbH
Priority date: 2021-12-20
Filing date: 2022-12-08
Publication date: 2024-10-11

Abstract

The present disclosure relates to precipitated silica characterized by a primary particle size average of greater than 80nm, a BET surface area of 10-40m ²/g, a total mercury intrusion volume of 0.75-2.00cc/g, and an oil absorption of 60-120cc/100 g. The silica of the present invention is produced by a process comprising (a) continuously feeding an acid and an alkali metal silicate or an alkaline earth metal silicate into a liquid medium with stirring at a silicate addition rate V1 and a temperature of 70-96 ℃ to form silica particles, (b) stopping feeding the alkali metal silicate or the alkaline earth metal silicate and the acid, and then raising the temperature to 90 to 100 ℃ with stirring, (c) adding the alkali metal silicate or the alkaline earth metal silicate and the acid with stirring, wherein the silicate addition rate is 1 to 40% of the silicate addition rate V1, and the pH value of 9.0 to 10.0 is kept constant by adjusting the acid rate during the addition of the alkali metal silicate or the alkaline earth metal silicate, (d) stopping the addition of the alkali metal silicate or the alkaline earth metal silicate, and adding the acid with stirring until the pH of 5.0 to 7.0 is reached. The precipitated silicas of the invention are useful in cosmetics, anti-caking free/flowing, food, carrier applications, dentifrices and mouthwashes.

Description

Precipitated silica and method thereof

Technical Field

The present disclosure relates generally to precipitated silica and methods of making and using the same.

Background

Porous precipitated silica is typically prepared by the reaction of an alkali silicate solution (e.g., sodium silicate) with a mineral acid. Sulfuric acid is mainly used commercially, although other acids, such as hydrochloric acid, may also be used. The acid and sodium silicate solution are added simultaneously to the water with stirring. When silica precipitates from the dispersion due to the neutralization reaction and the production of sodium salt (sodium sulfate) as a byproduct, precipitated silica is produced. Precipitated silica consists of aggregates (secondary particles) of primary (or final) colloidal silica particles. The primary particles are mostly spherical and generally have a diameter in the range of 5 to 50 nm. The primary particles in the aggregate are covalently bonded to each other by the formation of siloxane bonds. Aggregates are three-dimensional clusters of these primary particles. The aggregates have a diameter of up to 500 nm. During the preparation process, the aggregates are not chemically linked into a huge gel network. The aggregates themselves can be physically linked to larger agglomerates up to 100 μm in diameter by forming hydrogen bonds between silanol groups on their surface prior to milling. The median size of the agglomerates is about 20-50 μm in diameter (prior to milling). The porosity and surface area of these precipitated silica particles vary with the size of the primary particles and how they agglomerate and agglomerate. The pores are formed by the spaces between the primary particles and the aggregates. Typical surface areas of commercial precipitated silicas are in the range of 5 to 800m ²/g. They are sold in powder form. The tamped density, which is a measure of the weight of these porous powders, is in the range of 50-500kg/m ³. They have a high absorption capacity of about 175-320g/100 g.

U.S. patent No. 8,597,425 reports that porous precipitated silica having a primary particle size of 10-80nm can be used in 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-resistant areas (non-IMPACT PRINTING sector), articles in the pulp or personal care areas, and the like.

The use of precipitated silica having a primary particle size of 12-51nm for cosmetic applications including toothpastes is reported in J.Soc cosnet.chem August 1978,29,497-521.

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

U.S. patent No. 6,946,119 discloses a precipitated silica product comprising silica particles having a median diameter of 1-100 microns supporting thereon a surface deposit comprising active precipitated amorphous silica, a material present in an amount effective to provide the silica particles with a BET specific surface area of 1 to 50m ²/g. Precipitated silica is used in oral care applications.

U.S. patent No. 7,255,852 describes a precipitated silica comprising a silica particle product having a porous surface, the silica particles having an accumulated surface area of less than 8m ²/g of all pores having a diameter greater than 500A (as measured by mercury porosimetry), a BET specific surface area of less than about 20m ²/g, and a cetylpyridinium chloride compatibility percent (% CPC) of greater than 55%. Precipitated silica is used in oral care applications.

U.S. patent No. 7,438,895 discloses an abrasive precipitated silica material having a precipitated silica coating thereon, wherein the precipitated silica coating is denser than the material to which it is applied, and wherein the coated precipitated silica material exhibits a median particle diameter between 5.5 and 8 microns, a pore area of pores having a diameter greater than 500A of up to about 2.4m ²/g, and a percent cetylpyridinium chloride compatibility of at least 90% after aging the material at 140°f for 7 days.

U.S. 200802160053 describes a method of making an abrasive silica material, wherein the method comprises the sequential steps of: reacting, under high shear mixing conditions, a first amount of silicate and a first amount of acid together, optionally in the presence of at least one electrolyte present in an amount of 5 to 25% (weight/weight basis) compared to the dry weight of the first amount of silicate, to form a first silica material; and reacting a second amount of silicate and a second amount of acid together, optionally in the presence of at least one electrolyte present in an amount of 5 to 25% (based on weight/weight) compared to the dry weight of the second amount of 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; wherein the at least one electrolyte is present in either or both of the steps "a" or "b", and wherein the step "b" is optionally performed under high shear mixing conditions.

U.S. patent No. 10,328,002 discloses a dentifrice (dentifrice) composition comprising: an abrasive comprising precipitated silica particles, the precipitated silica particles characterized by: a BET surface area in the range of about 0.1 to about 9m ²/g; a bulk density (PACK DENSITY) in the range of about 35 to about 55lb/ft 3; einlehner abrasion values in the range of about 8 to about 25mg loss per 100,000 revolutions; a total mercury intrusion pore volume in the range of about 0.4-1.2 cc/g; and stannous compatibility in the range of about 70 to about 99%; wherein the abrasive comprises macropores of about 1000 angstroms or greater in size and lacks micropores of less than about 500-1000 angstroms in size.

WO 2018114280 describes silica particles having: a BET surface area in the range of about 0.1 to about 7m ²/g; a bulk density in the range of about 35 to about 55lb/ft 3; einlehner abrasion values in the range of about 8 to about 25mg loss per 100,000 revolutions; a total mercury intrusion pore volume in the range of about 0.7 to about 1.2cc/g, and a stannous compatibility in the range of about 70 to about 99%.

U.S.20190374448 discloses a dentifrice composition comprising: an adhesive; a surfactant; silica particles; wherein the silica particles comprise: a d50 median particle size in the range of about 4 to about 25 μm; a BET surface area in the range of 0 to about 10m ²/g; and a total mercury intrusion pore volume in the range of about 0.2 to about 1.5 cc/g.

WO 2019238777 describes silica particles characterized in that: (i) a d50 median particle size in the range of about 8 to about 20 μm; (ii) a sphericity factor greater than or equal to about 0.9 (S80); (iii) A BET surface area in the range of about 0.1 to about 8m ²/g; (iv) A total mercury intrusion pore volume in the range of about 0.35 to about 0.8 cc/g; (v) Loss On Ignition (LOI) in the range of about 3 to about 7 weight percent.

Precipitated silica provides compatibility with ingredients while providing the correct balance of cleaning and abrasion, which is important in toothpaste formulations. None of the prior art addresses the lack of compatibility with other ingredients (such as CPC and BAC) and fragrance compatibility, and does not achieve both PCR (80-110) and RDA (100-220) values within the normal range.

Disclosure of Invention

The inventors of the present invention have now found that in oral care applications having acceptable PCR/RDA values within the range of current silica cleaners, silica having a high primary particle size can result in high compatibility with CPC, BAC and/or flavours.

Accordingly, the subject of the present invention is precipitated silica characterized by a primary particle size mean of greater than 80nm, preferably greater than 90nm, more preferably greater than 100nm, still preferably greater than 110nm, most preferably between 120nm and 500nm, a BET surface area of 10-40m ²/g, preferably 10-26m ²/g, more preferably 10-23m ²/g, most preferably 10-20m ²/g, a total mercury intrusion volume of 0.75-2.00cc/g, preferably 0.80-1.80cc/g, more preferably 0.85-1.65cc/g, more preferably 0.90-1.50cc/g, and an oil absorption of 60-120cc/100g, preferably 60-110cc/100g, more preferably 60-100cc/100 cc, most preferably 60-90cc/100 g.

The subject of the invention is also a method comprising:

(a) Acid and alkali metal silicate or alkaline earth metal silicate are continuously fed into the liquid medium with stirring at a silicate addition rate V1 and a temperature of 70-96 ℃ to form silica particles,

(B) The alkali metal silicate or alkaline earth metal silicate and the acid are stopped from being fed and then the temperature is raised to 90 to 100 c, preferably 94 to 96 c with stirring,

(C) Adding an alkali metal silicate or alkaline earth metal silicate and an acid with stirring, wherein the silicate addition rate is 1 to 40%, preferably 1 to 30%, more preferably 2 to 10%, still preferably 3 to 5% of the silicate addition rate V1, and the pH value of 9.0 to 10.0, preferably 9.5 to 9.9, more preferably 9.6 to 9.8 is kept constant by adjusting the acid rate during the addition of the alkali metal silicate or alkaline earth metal silicate,

(D) The addition of alkali metal silicate or alkaline earth metal silicate is stopped and the acid is added with stirring until a pH of 5.0 to 7.0, preferably 5.5 to 6.5 is reached.

Another subject of the invention is the use of the silicas according to the invention in cosmetics, anti-caking free/flow (anti-CAKING FREE/flow), food, carrier applications, dentifrices and mouthwashes.

Detailed Description

The precipitated silicas of the invention have a primary particle size average of greater than 80nm, preferably greater than 90nm, more preferably greater than 100nm, still preferably greater than 110nm, most preferably between 120nm and 500nm, a BET surface area of 10-40m ²/g, preferably 10-26m ²/g, more preferably 10-23m ²/g, most preferably 10-20m ²/g, a total mercury intrusion volume of 0.75-2.00cc/g, preferably 0.80-1.80cc/g, more preferably 0.85-1.65cc/g, more preferably 0.90-1.50cc/g, and an oil absorption of 60-120cc/100g, preferably 60-110cc/100g, more preferably 60-100cc/100g, most preferably 60-90cc/100 g.

The silica of the present invention has a high primary particle diameter.

The precipitated silica according to the invention may have a CTAB surface area of from 10 to 35m ²/g, preferably from 20 to 30m ²/g.

The precipitated silica according to the invention may have a bulk density of from 0.40 to 0.80g/cm ³, preferably from 0.48 to 0.75g/cm ³.

Precipitated silicas according to the invention may have Einlehner values of less than 18mg loss per 100k revolutions, preferably 3 to 18mg loss per 100k revolutions.

The C content of the silica according to the invention may be lower than 3%, preferably lower than 1%, more preferably from 0% to 0.5%, most preferably from 0% to 0.1%.

The precipitated silica according to the invention may have a primary particle size average of greater than 90nm, a BET surface area of 10-26m ²/g, a total mercury intrusion volume (total mercury intruded volume) of 0.75-2.00cc/g and an oil absorption of 60-120cc/100 g.

The precipitated silica according to the invention may have a primary particle size average of greater than 80nm, a BET surface area of 10-30m ²/g, a total mercury intrusion volume of 0.80-1.80cc/g and an oil absorption of 70-110cc/100 g.

The precipitated silica according to the invention may have a primary particle size average of greater than 90nm, a BET surface area of 10-26m ²/g, a total mercury intrusion volume of 0.80-1.80cc/g and an oil absorption of 70-110cc/100 g.

The precipitated silica according to the invention may have a primary particle size average of greater than 100nm, a BET surface area of 10-23m ²/g, a total mercury intrusion volume of 0.75-2.00cc/g and an oil absorption of 60-120cc/100 g.

The precipitated silica according to the invention may have a primary particle size average of greater than 80nm, a BET surface area of 10-30m ²/g, a total mercury intrusion volume of 0.85-1.65cc/g and an oil absorption of 60-100cc/100 g.

The precipitated silica according to the invention may have a primary particle size average of greater than 100nm, a BET surface area of 10-23m ²/g, a total mercury intrusion volume of 0.85-1.65cc/g and an oil absorption of 60-100cc/100 g.

The precipitated silica according to the invention may have a primary particle size average of 120-500nm, a BET surface area of 10-20m ²/g, a total mercury intrusion volume of 0.75-2.00cc/g and an oil absorption of 60-120cc/100 g.

The precipitated silica according to the invention may have a primary particle size average of greater than 80nm, a BET surface area of 10-30m ²/g, a total mercury intrusion volume of 0.90-1.50cc/g and an oil absorption of 60-90cc/100 g.

The precipitated silica according to the invention may have a primary particle size average of 120-500nm, a BET surface area of 10-20m ²/g, a total mercury intrusion volume of 0.90-1.50cc/g and an oil absorption of 60-90cc/100 g.

The method according to the invention comprises at least four steps:

(a) Continuously feeding an acid and an alkali metal silicate or an alkaline earth metal silicate into a liquid medium with stirring at a silicate addition rate V1 and a temperature of 70-96 ℃ to form silica particles

(C) Adding an alkali metal silicate or alkaline earth metal silicate and an acid with stirring, wherein the silicate addition rate is 1 to 40%, preferably 5 to 30%, more preferably 7 to 25%, still preferably 10 to 20% of the silicate addition rate V1, and the pH value of 9.0 to 10.0, preferably 9.5 to 9.9, more preferably 9.6 to 9.8 is kept constant by adjusting the acid rate during the addition of the alkali metal silicate or alkaline earth metal silicate,

The silica of step (d) may be filtered (e), for example in a filter press.

The silica of step (e) may be dried (f), for example in a spray dryer.

The silica of step (f) may be milled.

Preferably 35 to 65% of the total volume of alkali metal silicate or alkaline earth metal silicate is added during step (a).

The liquid medium in step (a) may be an alkali metal silicate or an alkaline earth metal silicate and water.

The temperature in step (a) may range from 70 to 95 ℃, preferably from 70 to 90 ℃, more preferably from 80 to 90 ℃.

The acid rate in step (a) may be sufficient to maintain a pH between 8.5 and 10.5, more preferably 9.5 to 10.2.

The silicate rate in step (c) may be slowed to 5 to 30%, more preferably 10 to 20% of the rate in step (a).

The alkali metal silicate in steps (a) and (c) may preferably be sodium silicate.

The silicate addition rate in step (c) may be adjusted so that the%/hr of silicate added in this step is less than 30%/hr, preferably 15 to 25%/hr, based on the total amount of silicate added during the batch. The% of silicate added/hr is calculated by: the volume of silicate used in step (c)/time in hours of step (c)/volume of silicate used in step (a) and step (c) is 100.

The acid in steps (a), (c) and (d) may preferably be sulfuric acid.

The time of step (c) may be from 100 to 500 minutes, preferably from 150 to 300 minutes.

The precipitated silica of the present invention may be produced by the process of the present invention.

The precipitated silicas of the invention are useful in cosmetics, anti-caking free/flowing, food, carrier applications, dentifrices and mouthwashes.

The precipitated silica of the present invention has improved compatibility with cetylpyridinium chloride (CPC), benzalkonium chloride (BAC) and flavors in oral care applications.

Examples

Primary particle diameter mean value as determined by SEM

Images were taken by scanning electron microscopy at 50,000 times magnification. The image is sputtered with platinum and care is taken so that sputtering does not cause texturing of the particle surface, as this may be mistaken for the primary structure. The image must represent the entire sample and contain a minimum of 30 particles. The primary particles are then measured. If the particles are not perfectly circular, a minimum diameter across each particle is used. Particles on the edges of the image that cannot be fully observed should not be used. The mean and median values are then calculated based on the data set.

Carbon content

The carbon content was measured on a LECO SC832 carbon/sulfur analyzer.

Brightness of light

The silica samples were pressed into smooth surfaced pellets and analyzed using TECHNIDYNE BRIGHTMETER S-5/BC. The instrument has a dual beam optical system in which the sample is illuminated at an angle of 45 ° and the reflected light is observed at 0 °. Which complies with TAPPI test methods T452 and T646, and ASTM standard D985. The powder material was pressed into pellets of about 1cm with sufficient pressure to smooth the pellet surface without loose particles or gloss.

Moisture content

Moisture was determined by heating the silica at 105 ℃ for 2 hours.

BET surface area

The BET surface area of the silica of the present invention is determined by the BET nitrogen adsorption method of Brunaur et al j.am.chem.soc.,60,309 (1938) using a Micromeritics TriStar 3020 instrument, which is known in the art of particulate materials such as silica and silicate materials.

Oil absorption

The oil absorption value is determined using linseed oil (oil absorbed per 100g of particles (cc)) according to the rub-out method described in ASTM D281. In general, higher oil absorption levels indicate higher structure particles, while lower values generally indicate lower structure particles.

Total mercury intrusion volume

Mercury intrusion volume or total pore volume (Hg) was measured by mercury porosimetry (mercury porosimetry) using Micromeritics AutoPore IV 9520 (or Micromeritics AutoPore V9620) equipment. The pore diameter is calculated by the Washburn equation using a contact angle Theta (Θ) equal to 130 DEG and a surface Zhang Liga ma equal to 484 dyne/cm. Due to the pressure, mercury is forced into the voids of the particles and the volume of mercury pressed per gram of sample is calculated at each pressure setting. The total pore volume expressed herein represents the cumulative volume of mercury pressed in from vacuum to a pressure of 60,000 psi. The volume increase (cm ³/g) at each pressure setting is plotted against the pore radius or diameter corresponding to that pressure setting increase. The peak in the pressed volume versus pore radius or diameter curve corresponds to the pattern in the pore size distribution and determines the most common pore size in the sample. Specifically, the sample size was adjusted to achieve a stem volume of 25 to 90% in a powder penetrometer (penetrometer) having a 5mL bulb and a stem volume of about 1.1 mL. The sample was evacuated to a pressure of 50 μm Hg and held for 5 minutes. Mercury fills the pores at pressures of 4.0 to 60,000psi, with an equilibration time of 10 seconds per data collection point. The total pore volume as described above captures the volume of intra-particle porosity created by the pore structure within each particle, as well as the volume of inter-particle porosity created by the interstitial spacing of the filled particles under pressure. In order to better separate and measure the actual intra-particle porosity of the amorphous silica produced by inspection, a pore volume of <0.11 μm may be used.

Einlehner

EINLEHNER AT-1000Abrader were used as follows: (1) The pre-cleaned and dried Fourdrinier brass wire mesh is weighed and exposed to the action of a 10% aqueous silica suspension for a fixed length of time, specifically 100g of the sample is in 900g of deionized water; (2) The amount of wear was then measured as milligrams of brass lost per 100,000 revolutions of the Fourdrinier wire. The results measured in mg loss were characterized as 10% Brass EINLEHNER (BE) wear values.

CTAB surface area

The CTAB surface area disclosed herein is determined by absorption of CTAB (cetyltrimethylammonium bromide) on the silica surface, excess by centrifugation, and the amount determined by titration with sodium dodecyl sulfate using a surfactant electrode. Specifically, about 0.5g of silica particles were placed in a 250mL beaker containing 100mL of CTAB solution (5.5 g/L), mixed for 1 hour on an electric stirring plate, and then centrifuged at 10,000RPM for 30 minutes. 1mL of 10% Triton X-100 was added to 5mL of clear supernatant in a 100mL beaker. The pH was adjusted to 3 to 3.5 with 0.1N HCl and the samples were titrated with 0.01M sodium dodecyl sulfate using a surfactant electrode (Brinkmann SUR 1501-DL) to determine endpoint.

Particle size

The particle size of the silica of the present invention was measured by the angle of the scattered laser light on a HORIBA laser scattering dry particle size distribution analyzer LA-960.

Water corrected AbC value

The water absorption value was determined using an absorber "C" torque rheometer from c.w. brabender Instruments, inc. About 1/3 cup of the sample of silica was transferred to the mixing chamber of the absorber and mixed at 150 RPM. Water was then added at a rate of 6mL/min and the torque required to mix the powders was recorded. When water is absorbed by the powder, the torque reaches a maximum when the powder changes from free-flowing to pasty. The total volume of water added at the time of maximum torque was then normalized to the amount of 100g of powder absorbable water. Since the powder was used on an as-is basis (not previously dried), the free moisture value of the powder was used to calculate the "moisture corrected water AbC value" by the following equation.

PH 5 wt.%

The 5% ph was measured by weighing 5.0g of the sample (accurate to 0.1 g) and transferring the weighed sample into a 250mL beaker. 95mL 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.

Bulk density and pour Density

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

Example 1A: (inventive example)

383ML of sodium silicate (2.65 MR,1.193 g/mL) and 957mL of water were added to a 7L laboratory scale reactor and heated to 85℃under agitation at 350RPM from an overhead stirrer equipped with propeller blades. Once 85℃was reached, sodium silicate (2.65 MR,1.193 g/mL) and sulfuric acid (1.121 g/mL) were added simultaneously at rates of 39.0mL/min and 16.4mL/min, respectively, for 38 minutes. After 38 minutes, the flow of sodium silicate and sulfuric acid was stopped and the reaction mixture was heated to 95 ℃. Once 95℃is reached, sodium silicate (2.65 MR,1.193 g/mL) is added at 10.2mL/min and sulfuric acid (1.121 g/mL) is added at a rate sufficient to maintain a pH of 9.6 (+/-0.1) for an additional 150 minutes. After this additional 150 minutes, the flow of sodium silicate was stopped and the pH was adjusted to pH 6.0 by continuing to flow sulfuric acid (1.121 g/mL) at a rate of 5.1 mL/min. Once the pH had stabilized at pH 6.0, the batch was filtered, washed with 14L of water and dried overnight at 105 ℃.

Example 1B: (inventive example)

273ML of sodium silicate (2.65 MR,1.193 g/mL) and 681mL of water were added to a 7L laboratory scale reactor and heated to 85℃with stirring at 350RPM from an overhead stirrer equipped with propeller blades. Once 85℃was reached, sodium silicate (2.65 MR,1.193 g/mL) and sulfuric acid (1.121 g/mL) were added simultaneously at rates of 27.7mL/min and 11.7mL/min, respectively, for 38 minutes. After 38 minutes, the flow of sodium silicate and sulfuric acid was stopped and the reaction mixture was heated to 95 ℃. Once 95℃is reached, sodium silicate (2.65 MR,1.193 g/mL) is added at 10.7mL/min and sulfuric acid (1.121 g/mL) is added at a rate sufficient to maintain a pH of 9.6 (+/-0.1) for an additional 210 minutes. After this additional 210 minutes, the flow of sodium silicate was stopped and the pH was adjusted to pH 6.0 by continuing to flow sulfuric acid (1.121 g/mL) at a rate of 5.1 mL/min. Once the pH had stabilized at pH 6.0, the batch was filtered, washed with 14L of water and dried overnight at 105 ℃.

Example 1C: (inventive example)

273ML of sodium silicate (2.65 MR,1.193 g/mL) and 681mL of water were added to a 7L laboratory scale reactor and heated to 85℃with stirring at 350RPM from an overhead stirrer equipped with propeller blades. Once 85℃was reached, sodium silicate (2.65 MR,1.193 g/mL) and sulfuric acid (1.121 g/mL) were added simultaneously at rates of 43.8mL/min and 18.4mL/min, respectively, for 38 minutes. After 38 minutes, the flow of sodium silicate and sulfuric acid was stopped and the reaction mixture was heated to 95 ℃. Once 95℃is reached, sodium silicate (2.65 MR,1.193 g/mL) is added at 9.8mL/min and sulfuric acid (1.121 g/mL) is added at a rate sufficient to maintain a pH of 9.6 (+/-0.1) for an additional 120 minutes. After this additional 120 minutes, the flow of sodium silicate was stopped and the pH was adjusted to pH 6.0 by continuing to flow sulfuric acid (1.121 g/mL) at a rate of 4.7 mL/min. Once the pH had stabilized at pH 6.0, the batch was filtered, washed with 14L of water and dried overnight at 105 ℃.

Example 2A: (inventive example)

320ML of sodium silicate (2.65 MR,1.193 g/mL) and 824mL of water were added to a 7L laboratory scale reactor and heated to 85℃with stirring at 350RPM from an overhead stirrer equipped with propeller blades. Once 85℃was reached, sodium silicate (2.65 MR,1.193 g/mL) and sulfuric acid (1.121 g/mL) were added simultaneously at rates of 33.8mL/min and 15.1mL/min, respectively, for 47 minutes. After 47 minutes, the flow of sodium silicate and sulfuric acid was stopped and the reaction mixture was heated to 95 ℃. Once 95℃is reached, sodium silicate (2.65 MR,1.193 g/mL) is added at 10.4mL/min and sulfuric acid (1.121 g/mL) is added at a rate sufficient to maintain a pH of 9.6 (+/-0.1) for an additional 150 minutes. After this additional 150 minutes, the flow of sodium silicate was stopped and the pH was adjusted to pH 6.0 by continuing to flow sulfuric acid (1.121 g/mL) at a rate of 5.0 mL/min. Once the pH had stabilized at pH 6.0, the batch was filtered, washed with 14L of water and dried overnight at 105 ℃.

Table 1 shows the analytical values of the examples.

TABLE 1

Comparative example 5A:

594mL of sodium silicate (2.65 MR,1.193g/mL, heated to 80 ℃) and 1483mL of water were added to a 7L reactor and heated to 85℃with stirring at 350 RPM. Once 85℃is reached, sodium silicate (2.65 MR,1.193g/mL, heated to 80 ℃) and sulfuric acid (1.121 g/mL) are added simultaneously at rates of 60.4mL/min and 25.3mL/min, respectively, for 38 minutes. After 38 minutes, the flow of sodium silicate was stopped and the pH was adjusted to pH 6.0 by continuing to flow sulfuric acid (1.121 g/mL) at a rate of 25.3 mL/min. Once the pH had stabilized at pH 6.0, the batch was filtered, washed with 14L of water and oven dried overnight.

Comparative example 5B:

594mL of sodium silicate (2.65 MR,1.193g/mL, heated to 80 ℃) and 1483mL of water were added to a 7L reactor and heated to 85℃with stirring at 350 RPM. Once 85℃was reached, sodium silicate (2.65 MR,1.193g/mL, heated to 80 ℃) and sulfuric acid (1.121 g/mL) were added simultaneously at rates of 60.4mL/min and 21.6mL/min, respectively, for 38 minutes. After 38 minutes, the flow of sodium silicate was stopped and the pH was adjusted to pH 6.0 by continuing to flow sulfuric acid (1.121 g/mL) at a rate of 21.6 mL/min. Once the pH had stabilized at pH 6.0, the batch was filtered, washed with 14L of water and oven dried overnight.

Comparative example 5C:

594mL of sodium silicate (2.65 MR,1.193g/mL, heated to 80 ℃) and 1483mL of water were added to a 7L reactor and heated to 85℃with stirring at 350 RPM. Once 85℃is reached, sodium silicate (2.65 MR,1.193g/mL, heated to 80 ℃) and sulfuric acid (1.121 g/mL) are added simultaneously at rates of 60.4mL/min and 29.2mL/min, respectively, for 38 minutes. After 38 minutes, the flow of sodium silicate was stopped and the pH was adjusted to pH 6.0 by continuing to flow sulfuric acid (1.121 g/mL) at a rate of 29.2 mL/min. Once the pH had stabilized at pH 6.0, the batch was filtered, washed with 14L of water and oven dried overnight.

Comparative example 5D:

Comparative example 5E:

594mL of sodium silicate (2.65 MR,1.193g/mL, heated to 80 ℃) and 1483mL of water were added to a 7L reactor and heated to 85℃with stirring at 350 RPM. Once 85℃is reached, sodium silicate (2.65 MR,1.193g/mL, heated to 80 ℃) and sulfuric acid (1.121 g/mL) are added simultaneously at rates of 60.4mL/min and 19.1mL/min, respectively, for 38 minutes. After 38 minutes, the flow of sodium silicate was stopped and the pH was adjusted to pH 6.0 by continuing to flow sulfuric acid (1.121 g/mL) at a rate of 19.1 mL/min. Once the pH had stabilized at pH 6.0, the batch was filtered, washed with 14L of water and oven dried overnight.

Table 2 shows the analytical values for the examples.

TABLE 2

Comparative example 6A

594ML of sodium silicate (2.65 MR,1.193g/mL, heated to 80 ℃) and 1483mL of water were added to a 7L reactor and heated to 80℃with stirring at 350 RPM. Once 85℃was reached, sodium silicate (2.65 MR,1.193g/mL, heated to 80 ℃) and sulfuric acid (1.121 g/mL) were added simultaneously at rates of 60.4mL/min and 21.6mL/min, respectively, for 38 minutes. After 38 minutes, the flow of sodium silicate was stopped and the pH was adjusted to pH 6.0 by continuing to flow sulfuric acid (1.121 g/mL) at a rate of 21.6 mL/min. Once the pH had stabilized at pH 6.0, the batch was filtered, washed with 14L of water and oven dried overnight.

Comparative example 6B

594ML of sodium silicate (2.65 MR,1.193g/mL, heated to 85 ℃) and 1483mL of water were added to a 7L reactor and heated to 90℃with stirring at 350 RPM. Once 85℃was reached, sodium silicate (2.65 MR,1.193g/mL, heated to 85 ℃) and sulfuric acid (1.121 g/mL) were added simultaneously at rates of 60.4mL/min and 21.6mL/min, respectively, for 38 minutes. After 38 minutes, the flow of sodium silicate was stopped and the pH was adjusted to pH 6.0 by continuing to flow sulfuric acid (1.121 g/mL) at a rate of 21.6 mL/min. Once the pH had stabilized at pH 6.0, the batch was filtered, washed with 14L of water and oven dried overnight.

Comparative example 6C

594ML of sodium silicate (2.65 MR,1.193g/mL, heated to 90 ℃) and 1483mL of water were added to a 7L reactor and heated to 95℃with stirring at 350 RPM. Once 85℃is reached, sodium silicate (2.65 MR,1.193g/mL, heated to 90 ℃) and sulfuric acid (1.121 g/mL) are added simultaneously at rates of 60.4mL/min and 21.6mL/min, respectively, for 38 minutes. After 38 minutes, the flow of sodium silicate was stopped and the pH was adjusted to pH 6.0 by continuing to flow sulfuric acid (1.121 g/mL) at a rate of 21.6 mL/min. Once the pH had stabilized at pH 6.0, the batch was filtered, washed with 14L of water and oven dried overnight.

Table 3 shows the analytical values for the examples.

TABLE 3 Table 3

Comparative example 7A:

594mL of sodium silicate (2.65 MR,1.193g/mL, heated to 80 ℃) and 1483mL of water were added to a 7L reactor and heated to 85℃with stirring at 650 RPM. Once 85℃was reached, sodium silicate (2.65 MR,1.193g/mL, heated to 80 ℃) and sulfuric acid (1.121 g/mL) were added simultaneously at rates of 60.4mL/min and 25.4mL/min, respectively, for 38 minutes. After 38 minutes, the flow of sodium silicate was stopped and the pH was adjusted to pH 6.0 by continuing to flow sulfuric acid (1.121 g/mL) at a rate of 25.4 mL/min. Once the pH had stabilized at pH 6.0, the batch was filtered, washed with 14L of water and oven dried overnight.

Table 4 shows the analytical values for the examples.

TABLE 4 Table 4

Comparative example 8A

510ML of sodium silicate (2.65 MR,1.193g/mL, heated to 80 ℃) and 1310mL of water were added to a 7L reactor and heated to 80℃with stirring at 350 RPM. Once 85℃was reached, sodium silicate (2.65 MR,1.193g/mL, heated to 80 ℃) and sulfuric acid (1.121 g/mL) were added simultaneously at rates of 53.7mL/min and 24.0mL/min, respectively, for 38 minutes. After 38 minutes, the flow of sodium silicate was stopped and the pH was adjusted to pH 6.0 by continuing to flow sulfuric acid (1.121 g/mL) at a rate of 24.0 mL/min. Once the pH had stabilized at pH 6.0, the batch was filtered, washed with 14L of water and oven dried overnight.

Comparative example 8B

510ML of sodium silicate (2.65 MR,1.193g/mL, heated to 80 ℃) and 1310mL of water were added to a 7L reactor and heated to 80℃with stirring at 350 RPM. Once 85℃was reached, sodium silicate (2.65 MR,1.193g/mL, heated to 80 ℃) and sulfuric acid (1.121 g/mL) were added simultaneously at rates of 53.7mL/min and 27.5mL/min, respectively, for 38 minutes. After 38 minutes, the flow of sodium silicate was stopped and the pH was adjusted to pH 6.0 by continuing to flow sulfuric acid (1.121 g/mL) at a rate of 27.5 mL/min. Once the pH had stabilized at pH 6.0, the batch was filtered, washed with 14L of water and oven dried overnight.

Comparative example 8C

510ML of sodium silicate (2.65 MR,1.193g/mL, heated to 80 ℃) and 1310mL of water were added to a 7L reactor and heated to 80℃with stirring at 350 RPM. Once 85℃is reached, sodium silicate (2.65 MR,1.193g/mL, heated to 80 ℃) and sulfuric acid (1.121 g/mL) are added simultaneously at rates of 53.7mL/min and 20.4mL/min, respectively, for 38 minutes. After 38 minutes, the flow of sodium silicate was stopped and the pH was adjusted to pH 6.0 by continuing to flow sulfuric acid (1.121 g/mL) at a rate of 20.4 mL/min. Once the pH had stabilized at pH 6.0, the batch was filtered, washed with 14L of water and oven dried overnight.

Comparative example 8D

510ML of sodium silicate (2.65 MR,1.193g/mL, heated to 80 ℃) and 1310mL of water were added to a 7L reactor and heated to 80℃with stirring at 350 RPM. Once 85℃is reached, sodium silicate (2.65 MR,1.193g/mL, heated to 80 ℃) and sulfuric acid (1.121 g/mL) are added simultaneously at rates of 53.7mL/min and 19.2mL/min, respectively, for 38 minutes. After 38 minutes, the flow of sodium silicate was stopped and the pH was adjusted to pH 6.0 by continuing to flow sulfuric acid (1.121 g/mL) at a rate of 19.2 mL/min. Once the pH had stabilized at pH 6.0, the batch was filtered, washed with 14L of water and oven dried overnight.

Comparative example 8E

510ML of sodium silicate (2.65 MR,1.193g/mL, heated to 80 ℃) and 1310mL of water were added to a 7L reactor and heated to 80℃with stirring at 350 RPM. Once 85℃was reached, sodium silicate (2.65 MR,1.193g/mL, heated to 80 ℃) and sulfuric acid (1.121 g/mL) were added simultaneously at rates of 53.7mL/min and 18.0mL/min, respectively, for 38 minutes. After 38 minutes, the flow of sodium silicate was stopped and the pH was adjusted to pH 6.0 by continuing to flow sulfuric acid (1.121 g/mL) at a rate of 18.0 mL/min. Once the pH had stabilized at pH 6.0, the batch was filtered, washed with 14L of water and oven dried overnight.

Table 5 shows the analytical values for the examples.

TABLE 5

Example 10A: (inventive example)

62L of sodium silicate (2.65 MR,1.193g/mL, heated to 80 ℃) and 154L of water were added to a 1200L reactor and heated to 85℃with stirring at 80RPM and recirculation at 80L/min. Once 85℃is reached, sodium silicate (2.65 MR,1.193g/mL, heated to 80 ℃) and sulfuric acid (1.121 g/mL) are added simultaneously at rates of 6.27L/min and 2.24L/min, respectively, for 38 minutes. After 38 minutes, the flow of sodium silicate and sulfuric acid was stopped and the reaction mixture was heated to 95 ℃. Once 95℃is reached, sodium silicate (2.65 MR,1.193g/mL, heated to 80 ℃) is added at 1.63L/min and sulfuric acid (1.121 g/mL) is added at a rate sufficient to maintain a pH of 9.6 (+/-0.1) for an additional 150 minutes. After this additional 150 minutes, the flow of sodium silicate was stopped and the pH was adjusted to pH 6.0 by continuing to flow sulfuric acid (1.121 g/mL) at a rate of 0.82 mL/min. Once the pH stabilized at pH 6.0, the batch was filtered, washed until conductivity <1500 μs, spray dried to 5% target moisture, and milled to a particle size of about 10 μm.

Example 10B: (inventive example)

53L of sodium silicate (2.65 MR,1.193g/mL, heated to 80 ℃) and 133L of water were added to a 1200L reactor and heated to 85℃with stirring at 80RPM and recirculation at 80L/min. Once 85℃is reached, sodium silicate (2.65 MR,1.193g/mL, heated to 80 ℃) and sulfuric acid (1.121 g/mL) are added simultaneously at rates of 5.42L/min and 1.82L/min, respectively, for 38 minutes. After 38 minutes, the flow of sodium silicate and sulfuric acid was stopped and the reaction mixture was heated to 95 ℃. Once 95℃is reached, sodium silicate (2.65 MR,1.193g/mL, heated to 80 ℃) is added at 1.63L/min and sulfuric acid (1.121 g/mL) is added at a rate sufficient to maintain a pH of 9.6 (+/-0.1) for an additional 180 minutes. After this additional 180 minutes, the flow of sodium silicate was stopped and the pH was adjusted to pH 6.0 by continuing to flow sulfuric acid (1.121 g/mL) at a rate of 0.82 mL/min. Once the pH stabilized at pH 6.0, the batch was filtered, washed until conductivity <1500 μs, spray dried to 5% target moisture, and milled to a particle size of about 10 μm.

Example 10C: (inventive example)

44L of sodium silicate (2.65 MR,1.193g/mL, heated to 80 ℃) and 115L of water were added to a 1200L reactor and heated to 85℃with stirring at 80RPM and recirculation at 80L/min. Once 85℃is reached, sodium silicate (2.65 MR,1.193g/mL, heated to 80 ℃) and sulfuric acid (1.121 g/mL) are added simultaneously at rates of 4.48L/min and 1.51L/min, respectively, for 38 minutes. After 38 minutes, the flow of sodium silicate and sulfuric acid was stopped and the reaction mixture was heated to 95 ℃. Once 95℃is reached, sodium silicate (2.65 MR,1.193g/mL, heated to 80 ℃) is added at 1.73L/min and sulfuric acid (1.121 g/mL) is added for an additional 210 minutes at a rate sufficient to maintain a pH of 9.6 (+/-0.1). After this additional 210 minutes, the flow of sodium silicate was stopped and the pH was adjusted to pH 6.0 by continuing to flow sulfuric acid (1.121 g/mL) at a rate of 0.82 mL/min. Once the pH stabilized at pH 6.0, the batch was filtered, washed until conductivity <1500 μs, spray dried to 5% target moisture, and milled to a particle size of about 10 μm.

Tables 6a and 6b show the analytical values for the examples.

TABLE 6a

TABLE 6b

Example 11: toothpaste formula

The silicas from the above invention were incorporated into toothpastes for rheological and PCR/RDA measurements. The formulation and results (table 7 a) are shown below. Stannous compatibility and fluoride compatibility of the examples of the present invention are shown in table 7 b.

TABLE 7a

(PCR/RDA run at university of Indiana dental science institute)

TABLE 7b

The data in table 7a shows that toothpaste comprising the silica of the invention achieved PCR and RDA values within the normal range.

Stannous compatibility (%)

The stannous compatibility of the above samples was determined as follows. A stock solution was prepared comprising 431.11g of 70% sorbitol, 63.62g of deoxygenated deionized water, 2.27g of stannous chloride dihydrate and 3g of sodium gluconate (sodium gluconcate). 34g of the stock solution are added to a 50mL centrifuge tube containing 6g of the silica sample to be tested. The centrifuge tube was placed on a 5RPM rotating wheel (rotating wire) and aged for 1 week at 40 ℃. After aging, the centrifuge tube was centrifuged at 12,000rpm for 10 minutes and the stannous concentration in the supernatant was determined by ICP-OES (inductively coupled plasma emission spectroscopy). Stannous compatibility was determined by expressing the stannous concentration of the samples as a percentage of the stannous concentration of a solution prepared by the same procedure but without the addition of silica.

Fluoride compatibility (%)

The fluoride compatibility of the above samples was determined as follows. A fluoride stock solution containing 1624ppm was prepared. 30.0g of the stock solution was added to a 50mL centrifuge tube containing 7.0g of the silica sample to be tested. The centrifuge tube was placed on a 5RPM (or equivalent agitation) rotating wheel and aged at 60℃for 1 hour. After aging, the tube was centrifuged at 12,000rpm for 10 minutes (or until the supernatant clarified). Fluoride concentration in the supernatant was determined by first taking an aliquot and transferring it to a plastic bottle with a magnetic stir bar and an equal volume of TISAB II buffer. The concentration was then measured using a pre-calibrated fluoride specific ion electrode (Orion model #96-09BN or equivalent). Fluoride compatibility was determined by expressing the fluoride concentration of the sample as a percentage of the fluoride concentration of the stock solution.

Relative Dentin Abrasion (RDA)

The RDA values of the dentifrice compositions of examples DC1-DC14 containing the silicas of the present invention are determined according to Hefferen, journal of Dental Res., july-August 1976,55 (4), pp.563-573, and the methods described in Wason U.S. Pat. Nos. 4,340,583, 4,420,312 and 4,421,527, the contents of which are incorporated herein by reference in their entirety.

Bacterial film cleaning ratio ('PCR')

The cleaning performance of a dentifrice composition is typically expressed in terms of a pellicle film cleaning Ratio (PELLICLE CLEANING Ratio, "PCR") value. The PCR test measures the ability of a dentifrice composition to remove pellicle film from teeth under fixed brushing conditions. PCR assays are described in "In Vitro Removal of STAIN WITH DENTIFRICE" G.K.Stookey, et al, J.Dental Res.,61,12-36-9,1982. Both PCR and RDA results vary depending on the nature and concentration of the components of the dentifrice composition. PCR and RDA values are unitless.

Example 12: CPC and BAC compatibility

To determine a given silica capacitance (capacitance) for the quaternary ammonium compound, zeta potential titration was performed. In titration, a 5 wt% suspension of the desired silica was prepared by taking the desired amount of dry silica and diluting to 160g with deionized water. In order to be as close as possible to the 5% by weight (8 g) of silica required in 160g of suspension, the amount of silica used as such was adjusted to compensate for the amount of free moisture present (drying loss) and sodium sulphate. The suspension was magnetically stirred at 500rpm for 10 minutes to completely wet the silica, and then the suspension was adjusted to a pH of 8.5 with 0.5M NaOH or 0.5M HCl to aid in initial surface chemistry consistency and more direct comparison.

The suspension was then titrated with 0.25mL increments of 5wt% cetylpyridinium chloride (CPC) or 5wt% benzalkonium chloride (BAC), the capacitance of each silica was determined by the volume of CPC or BAC required to reach a zeta potential of 0 mV. Whereas most experiments showed artifacts near the 0mV crossover point, capacitance was defined as the first point at which the zeta potential became positive. The volume at this point was then used to determine the mass of CPC or BAC per gram of silica in mg/g.

Inventive examples 10A, 10B and 10C showed lower CPC and BAC values and thus showed improved CPC/BAC compatibility (table 8).

TABLE 8

Example 13: spice

The method comprises the following steps: 500mg of silica was placed in a headspace bottle. Add 10 μl of fragrance (lyme oil, lot MKCF9356 fragrance base) and allow the headspace bottle to equilibrate overnight. The samples were incubated at 60℃for 60 minutes with gentle shaking prior to headspace sampling. 1mL of headspace was analyzed in a GC/MS equipped with Stabilwax column (0.25 mm. Times.60 m) at a column flow rate of 1.606mL/min and having a temperature gradient of 6 ℃/min over a temperature range of 40℃to 230 ℃ (HS sampling: 1mL of headspace was sampled into a gas tight syringe at 65 ℃). Peak area relative to113 Was normalized for peak intensity.

Inventive examples 10A, 10B and 10C showed higher values and thus improved fragrance compatibility (table 9).

TABLE 9

Claims

1. Precipitated silica characterized by a primary particle size average of more than 80nm, preferably more than 90nm, more preferably more than 100nm, still preferably more than 110nm, most preferably between 120nm and 500nm, a BET surface area of 10-40m ²/g, preferably 10-26m ²/g, more preferably 10-23m ²/g, most preferably 10-20m ²/g, a total mercury intrusion volume of 0.75-2.00cc/g, preferably 0.80-1.80cc/g, more preferably 0.85-1.65cc/g, more preferably 0.90-1.50cc/g, and an oil absorption of 60-120cc/100g, preferably 60-110cc/100g, more preferably 60-100cc/100g, most preferably 60-90cc/100 g.

2. The precipitated silica of claim 1, wherein the precipitated silica has a CTAB surface area of 10-35m ²/g, preferably 20-30m ²/g.

3. Precipitated silica according to claim 1 or 2, wherein the precipitated silica has a bulk density of 0.40-0.80g/cm ³, preferably 0.48-0.75g/cm ³.

4. A precipitated silica according to any one of claims 1-3, wherein the precipitated silica has an Einlehner value of less than 18mg loss per 100k revolutions, preferably 3 to 18mg loss per 100k revolutions.

5. The precipitated silica of any one of claims 1-4, wherein the precipitated silica has a C content of less than 3%, preferably less than 1%, more preferably from 0% to 0.5%.

6. The precipitated silica of claim 1, wherein the precipitated silica has a primary particle size average of greater than 90nm, a BET surface area of 10 "26 m ²/g, a total mercury intrusion volume of 0.75" 2.00cc/g, and an oil absorption of 60 "120 cc/100 g.

7. The precipitated silica of claim 1, wherein the precipitated silica has a primary particle size average of greater than 80nm, a BET surface area of 10-30m ²/g, a total mercury intrusion volume of 0.80-1.80cc/g, and an oil absorption of 70-110cc/100 g.

8. The precipitated silica of claim 1, wherein the precipitated silica has a primary particle size average of greater than 90nm, a BET surface area of 10-26m ²/g, a total mercury intrusion volume of 0.80-1.80cc/g, and an oil absorption of 70-110cc/100 g.

9. The precipitated silica of claim 1, wherein the precipitated silica has a primary particle size average of greater than 100nm, a BET surface area of 10-23m ²/g, a total mercury intrusion volume of 0.75-2.00cc/g, and an oil absorption of 60-120cc/100 g.

10. The precipitated silica of claim 1, wherein the precipitated silica has a primary particle size average of greater than 80nm, a BET surface area of 10-30m ²/g, a total mercury intrusion volume of 0.85-1.65cc/g, and an oil absorption of 60-100cc/100 g.

11. The precipitated silica of claim 1, wherein the precipitated silica has a primary particle size average of greater than 100nm, a BET surface area of 10-23m ²/g, a total mercury intrusion volume of 0.85-1.65cc/g, and an oil absorption of 60-100cc/100 g.

12. A process for producing precipitated silica comprising

13. The process for producing precipitated silica according to claim 12, wherein the silica of step (d) is filtered (e) and dried (f) in a spray dryer.

14. The method for producing precipitated silica according to claim 13, wherein the silica of step (f) is ground.

15. The method for producing precipitated silica according to claim 12, wherein the liquid medium in step (a) is an alkali metal silicate or an alkaline earth metal silicate and water.

16. The method for producing precipitated silica according to claim 12, wherein the temperature in step (a) is in the range of 70 to 95 ℃, preferably 70 to 90 ℃, more preferably 80 to 90 ℃.

17. The method for producing precipitated silica according to claim 12, wherein the period of time of step (c) is 100 to 500 minutes, preferably 150 to 300 minutes.

18. Use of the precipitated silica according to claim 1 for cosmetics, anti-caking free/flowing, food, carrier applications, dentifrices and mouthwashes.

19. A dentifrice composition comprising the precipitated silica of any of claims 1-11.