# US 7,612,137 B2 · Surface-modified silica gels

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- Number: US 7,612,137 B2
- Document ID: US7612137B2
- Status: Granted
- Kind: B2
- Application number: 11/132,293
- Filed: 2005-05-19
- Published: 2005-12-22
- Granted: 2009-11-03
- Earliest claimed: 2004-06-16
- Assignees: Degussa AG
- Inventors: Ulrich Brinkmann; Christian Götz; Hans-Dieter Christian
- Web page: https://patentgrep.com/patent/US7612137B2

## CPC

- C09C 1/3081: {Treatment with organo-silicon compounds}
- C09D 5/04: Thixotropic paints
- C09D 7/42: Gloss-reducing agents
- C09D 7/62: modified by treatment with other compounds
- C09D 7/68: {Particle size between 100-1000 nm}
- C09D 7/69: {Particle size larger than 1000 nm}
- C01P 2004/51: Particles with a specific particle size distribution
- C01P 2006/11: Powder tap density
- C01P 2006/12: Surface area
- C01P 2006/14: Pore volume
- C01P 2006/19: Oil-absorption capacity, e.g. DBP values
- C01P 2006/22: Rheological behaviour as dispersion, e.g. viscosity, sedimentation stability
- C01P 2006/40: Electric properties
- C08K 3/36: Silica
- C08K 9/06: with silicon-containing compounds
- C09C: TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES (treatment of materials specially adapted to enhance their filling properties in mortars, concrete or artificial stone C04B14/00, C04B18/00, C04B20/00); PREPARATION OF CARBON BLACK {; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS}
- C09D: COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR (cosmetics A61K; processes for applying liquids or other fluent materials to surfaces, in general, B05D; staining wood B27K5/02; glazes or vitreous enamels C03C; natural resins, French polish, drying-oils, driers, turpentine, per se, C09F; polishing compositions other than French polish, ski waxes C09G; adhesives or use of materials as adhesives C09J; materials for sealing or packing joints or covers C09K3/10; materials for stopping leaks C09K3/12; processes for the electrolytic or electrophoretic production of coatings C25D)
- C01P: INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C08K: Use of inorganic or non-macromolecular organic substances as compounding ingredients (paints, inks, varnishes, dyes, polishes, adhesives C09)

## Abstract

The invention relates to surface-modified silica gels, to a process for preparing them, and to their use as matting agents in coating materials. As a result of the nature of the surface modification, the viscosity of 2-component coating materials is increased only slightly, or not at all, after the matting agent has been added.

## Claims

### Claim 1

A surface-modified silica gel which influences the viscosity of a 2-component reference varnish, containing 10.7% by weight of the surface-modified silica gel and stored, following preparation and addition of the surface-modified silica gel, at 23° C. and 50% relative humidity (RH) for 1 day, in such a way that the thixotropic index TI 6/60 is less than or equal to 4.5, wherein the surface of the silica gel is coated with a polyorganosiloxane having the following general structure:
with the proviso that a, b, c and d are each not 0 simultaneously.

### Claim 2 (depends on 1)

A surface-modified silica of gel as claimed in claim 1, wherein R=methyl or ethyl.

### Claim 3 (depends on 1)

A surface-modified silica gel as claimed in claim 1, which influences the viscosity of a 2-component reference varnish, containing 10.7% by weight of the surface-modified silica gel and stored, following preparation and addition of the surface-modified silica gel, at 23° C. and 50% relative humidity (RH) for 1 day, in such a way that the thixotropic index TI 6/60 is less than or equal to 4.0.

### Claim 4 (depends on 1)

A surface-modified silica gel as claimed in claim 1, which increases the viscosity of a 2-component reference varnish, containing 10.7% by weight of the surface-modified silica gel and stored, following preparation and addition of the surface-modified silica gel, at 23° C. and 50% relative humidity (RH) for 1 day, in the low-shear state to a maximum of 1200 mPa*s.

### Claim 5 (depends on 4)

A surface-modified silica gel as claimed in claim 4, which increases the viscosity of a 2-component reference varnish, containing 10.7% by weight of the surface-modified silica gel and stored, following preparation and addition of the surface-modified silica gel, at 23° C. and 50% relative humidity (RH) for 1 day in the low-shear state to a maximum of 900 mPa*s.

### Claim 6 (depends on 1)

A surface-modified silica gel as claimed in claim 1, having the following physicochemical data:
average particle size d50:
0.5-50 μm
DBP:
100-600 g/100 g
BET:
100-1000 m2/g
carbon content:
0.5-20%.

### Claim 7 (depends on 1)

A surface-modified silica gel as claimed in claim 1, which has a mesopore volume in the range from 2 to 50 nm of at least 1.0 ml/g.

### Claim 8 (depends on 1)

A surface-modified silica gel as claimed in claim 1, which has a span <1.3.

### Claim 9

A surface-modified silica gel which influences the viscosity of a 2-component reference varnish, containing 10.7% by weight of the surface-modified silica gel and stored, following preparation and addition of the surface-modified silica gel, at 23° C. and 50% relative humidity (RH) for 1 day, in such a way that the thixotropic index TI 6/60 is less than or equal to 4.5, wherein the surface of the silica gel is coated with a polyorganosiloxane having the following general structure:
and the sum of the units a=0 to 100, the sum of the units b=0 to 15, the ratio of methyl to alkoxy radicals R1 being less than 50:1, and b>1 if a=0 and a>5 if b=0.

### Claim 10 (depends on 9)

A surface-modified silica gel as claimed in claim 9, which influences the viscosity of a 2-component reference varnish, containing 10.7% by weight of the surface-modified silica gel and stored, following preparation and addition of the surface-modified silica gel, at 23° C. and 50% relative humidity (Rh) for 1 day, in such a way that the thixotropic index TI 6/60 is less than or equal to 4.0.

### Claim 11 (depends on 9)

A surface-modified silica gel as claimed in claim 9, which increases the viscosity of a 2-component reference varnish, containing 10.7% by weight of the surface-modified silica gel and stored, following preparation and addition of the surface-modified silica gel, at 23° C. and 50% relative humidity (RH) for 1 day, in the low-shear state to a maximum of 1200 mPa*s.

### Claim 12 (depends on 11)

A surface-modified silica gel as claimed in claim 11, which increases the viscosity of a 2-component reference varnish, containing 10.7% by weight of the surface-modified silica gel and stored, following preparation and addition of the surface-modified silica gel, at 23° C. and 50% relative humidity (RH) for 1 day in the low-shear state to a maximum of 900 mPa*s.

### Claim 13 (depends on 9)

A surface-modified silica gel as claimed in claim 9, having the following physicochemical data:
average particle size d50:
0.5-50 μm
DBP:
100-600 g/100 g
BET:
100-1000 m2/g
carbon content:
0.5-20%.

### Claim 14 (depends on 9)

A surface-modified silica gel as claimed in claim 9, which has a mesopore volume in the range from 2 to 50 nm of at least 1.0 ml/g.

### Claim 15 (depends on 9)

A surface-modified silica gel as claimed in claim 9, which has a span<1.3.

### Claim 16

A process for preparing a surface-modified silica gel which influences the viscosity of a 2-component reference varnish, containing 10.7% by weight of the surface-modified silica gel and stored, following preparation and addition of the surface-modified silica gel, at 23° C. and 50% relative humidity (RH) for 1 day, in such a way that the thixotropic index TI 6/60 is less than or equal to 4.5,
which comprises modifying the surface of a silica gel with a polyorganosiloxane having the following general structure:
with the proviso that a, b, c and d are each not 0 simultaneously.

### Claim 17 (depends on 16)

A process as claimed in claim 16, comprising the steps of
a) preliminary grinding of the hydrogel
b) drying of the hydrogel to give the xerogel
c) grinding of the xerogel
d) surface modification.

### Claim 18 (depends on 17)

A process as claimed in claim 17, wherein step d) is carried out before or during at least one of steps a) to c).

### Claim 19 (depends on 17)

A process as claimed in claim 17, wherein the polymer in step d) is added as the pure, undiluted substance or in dilute form as an aqueous emulsion.

### Claim 20 (depends on 17)

A process as claimed in claim 17, wherein in step a) or in step d), when performed before step a), a hydrogel is used which has the following physicochemical properties:
SiO2 fraction:
≧5%,
BET surface area:
200-500 m2/g.

### Claim 21 (depends on 20)

A process as claimed in claim 20, wherein in step a) or in step d), when performed before step a), a hydrogel is used which has the following physicochemical properties:
SiO2 fraction:
20%-40%,
BET surface area:
250-400 m2/g.

### Claim 22 (depends on 17)

A process as claimed in claim 17, wherein step d) is carried out before step b).

### Claim 23 (depends on 21)

A process as claimed in claim 21, wherein the hydrogel in step d) is mixed with 0.2% to 12% by weight of the polymer, based on the hydrogel.

### Claim 24 (depends on 21)

A process as claimed in claim 21, wherein the hydrogel in step d) is mixed with 0.5% to 5%, by weight of the polymer, based on the hydrogel.

### Claim 25 (depends on 17)

A process as claimed in claim 17, wherein the drying in step b) is carried out by means of spray dryers or grinding dryers or pneumatic dryers or spin-flash dryers.

### Claim 26 (depends on 17)

A process as claimed in claim 17, wherein step d) is carried out after step b) but before step c).

### Claim 27 (depends on 17)

A process as claimed in claim 17, wherein step d) is carried out during step c).

### Claim 28 (depends on 17)

A process as claimed in claim 17, wherein the grinding in step c) takes place by means of an air-jet or steam-jet mill or fluidized-bed opposed-jet mill.

### Claim 29 (depends on 17)

A process as claimed in claim 17, wherein after the surface-modified silica gel has been dried or after or during the grinding operation particles having a diameter of more than 50 μm are separated off.

### Claim 30

A process for preparing a surface-modified silica gel which influences the viscosity of a 2-component reference varnish, containing 10.7% by weight of the surface-modified silica gel and stored, following preparation and addition of the surface-modified silica gel, at 23° C. and 50% relative humidity (RH) for 1 day, in such a way that the thixotropic index TI 6/60 is less than or equal to 4.5,
which comprises modifying the surface of a silica gel with a polyorganosiloxane having the following general structure:
and the sum of the units a=0 to 100, the sum of the units b=0 to 15, the ratio of methyl to alkoxy radicals R1 being less than 50:1, and b>1 if a=0 and a>5 if b=0.

### Claim 31 (depends on 30)

A process as claimed in claim 30, comprising the steps of
a) preliminary grinding of the hydrogel
b) drying of the hydrogel to give the xerogel
c) grinding of the xerogel
d) surface modification.

### Claim 32 (depends on 31)

A process as claimed in claim 31, wherein step d) is carried out before or during at least one of steps a) to c).

### Claim 33 (depends on 30)

A process as claimed in claim 30, wherein the polymer in step d) is added as the pure, undiluted substance or in dilute form as an aqueous emulsion.

### Claim 34 (depends on 30)

A process as claimed in claim 30, wherein in step a) or in step d), when performed before step a), a hydrogel is used which has the following physicochemical properties:
SiO2 fraction:
≧5%,
BET surface area:
200-500 m2/g.

### Claim 35 (depends on 31)

A process as claimed in claim 31, wherein in step a) or in step d), when performed before step a), a hydrogel is used which has the following physicochemical properties:
SiO2 fraction:
20%-40%,
BET surface area:
250-400 m2/g.

### Claim 36 (depends on 31)

A process as claimed in claim 31, wherein step d) is carried out before step b).

### Claim 37 (depends on 36)

A process as claimed in claim 36, wherein the hydrogel in step d) is mixed with 0.2% to 12% by weight of the polymer, based on the hydrogel.

### Claim 38 (depends on 36)

A process as claimed in claim 36, wherein the hydrogel in step d) is mixed with 0.5% to 5% by weight of the polymer, based on the hydrogel.

### Claim 39 (depends on 31)

A process as claimed in claim 31, wherein the drying in step b) is carried out by means of spray dryers or grinding dryers or pneumatic dryers or spin-flash dryers.

### Claim 40 (depends on 31)

A process as claimed in claim 31, wherein step d) is carried out after step b) but before step c).

### Claim 41 (depends on 31)

A process as claimed in claim 31, wherein step d) is carried out during step c).

### Claim 42 (depends on 31)

A process as claimed in claim 31, wherein the grinding in step c) takes place by means of an air-jet or steam-jet mill or fluidized-bed opposed-jet mill.

### Claim 43 (depends on 31)

A process as claimed in claim 31, wherein after the surface-modified silica gel has been dried or after or during the grinding operation particles having a diameter of more than 50 μm are separated off.

### Claim 44 (depends on 1)

A coating formulation comprising a surface-modified silica gel as claimed in claim 1.

### Claim 45 (depends on 9)

A coating formulation comprising a surface-modified silica gel as claimed in claim 9.

### Claim 46 (depends on 1)

A method of preparing matting agents in inks and paints, paper coatings, defoamer formulations, reinforcing agents for silicone rubber or antiblocking agents for plastics, comprising incorporating the surface-modified silica gel as claimed in claim 1 into a matting agent in inks and paints, paper coating, defoamer formulation, reinforcing agent for silicone rubber or antiblocking agent for plastics.

### Claim 47 (depends on 1)

A method of preparing matting agents in inks and paints, paper coatings, defoamer formulations, reinforcing agents for silicone rubber or antiblocking agents for plastics, comprising incorporating the surface-modified silica gel as claimed in claim 1 into a matting agent in inks and paints, paper coating, defoamer formulation, reinforcing agent for silicone rubber or antiblocking agent for plastics.