Surface-treated magnesium hydroxide-comprising material

Abstract

The present invention refers to a process for the preparation of a surface-treated magnesium hydroxide-comprising material, a surface-treated magnesium hydroxide-comprising material as well as the use of the surface-treated magnesium hydroxide-comprising material in polymer composition, in paper making, paper coatings, agricultural applications, paints, adhesives, sealants, composite materials, wood composite materials, construction applications, pharma applications and/or cosmetic applications as well as surrounding materials, wherein the surface treatment agent of the surface-treated magnesium hydroxide-comprising material is undergoing a reaction with the surrounding material.

Claims

1. A surface-treated magnesium hydroxide-comprising material having a weight median particle size d.sub.50 value in the range from 0.25 ?m to 15 ?m, wherein the magnesium hydroxide-comprising material has been treated with at least one surface treatment agent that is a compound according to Formula (I), ##STR00007## wherein R.sup.1 is a hydrolysable alkoxy group, and R.sup.2, R.sup.3 and R.sup.4 are independently from each other selected from the group consisting of hydrogen, a hydroxyl group, an alkyl group, a vinyl group, an alkoxy group, an acyloxy group, an acryloxy group, a methacryloxy group, an ethacryloxy group, a carboxyl group, an epoxy group, an anhydride group, an ester group, an aldehyde group, an amino group, an ureido group, an azide group, a halogen group, a phosphonate group, a phosphine group, a sulphonate group, a sulphide group or disulphide group, an isocyanate group or masked isocyanate group, a thiol group, a phenyl group, a benzyl group, a styryl group, a benzoyl group and a fully or partially halogenated alkyl group having from 1 to 20 carbon atoms, and u, v and w are independently from each other an integer from 0 to 24, and wherein the surface-treated magnesium hydroxide-comprising material has a specific surface area (BET) of from 15 to 150 m.sup.2/g as measured using nitrogen and the BET method according to ISO 9277:2010, a moisture pick-up susceptibility of from 0.1 to 10 mg/g, and a moisture pick-up susceptibility to specific surface area (BET) ratio of 0.001 to 0.5 mg/m.sup.2; and wherein the moisture content of the surface-treated magnesium hydroxide-comprising material is in the range from 0.05 to 5 wt.-% based on the total weight of the surface-treated magnesium hydroxide-comprising material.

2. A surface-treated magnesium hydroxide-comprising material according to claim 1, having a moisture pick-up susceptibility to specific surface area (BET) ratio of from 0.06 to 0.09 mg/m.sup.2.

3. The surface-treated magnesium hydroxide-comprising material according to claim 1 wherein the at least one surface-treatment agent is selected from the group consisting of triethoxyvinyl silane, trim ethoxyvinyl silane, n-octadecyltriethoxysilane,1H,1H,2H,2H-perfluorodecyltriethoxysilane or 1H,1H,2H,2H-perfluorooctyltriethoxysilane and combinations thereof.

4. The surface-treated magnesium hydroxide-comprising material according to claim 1 wherein the weight median particle size d.sub.50 value is in the range from 1 ?m to 6 ?m.

5. A polymer composition comprising the surface-treated magnesium hydroxide-comprising material according to claim 1.

6. The surface-treated magnesium hydroxide-comprising material according to claim 1 wherein the weight median particle size d.sub.50 value is in the range from 0.5 ?m to 10 ?m.

7. The surface-treated magnesium hydroxide-comprising material according to claim 1 wherein the surface-treated magnesium hydroxide-comprising material has a specific surface area (BET) of from 20 to 80 m.sup.2/g as measured using nitrogen and the BET method according to ISO 9277:2010.

8. The surface-treated magnesium hydroxide-comprising material according to claim 1 wherein the surface-treated magnesium hydroxide-comprising material has a specific surface area (BET) of from 30 to 70 m.sup.2/g as measured using nitrogen and the BET method according to ISO 9277:2010.

9. The surface-treated magnesium hydroxide-comprising material according to claim 1 wherein the surface-treated magnesium hydroxide-comprising material has a moisture pick-up susceptibility of from 0.5 to 7 mg/g.

10. The surface-treated magnesium hydroxide-comprising material according to claim 1 wherein the surface-treated magnesium hydroxide-comprising material has a moisture pick-up susceptibility of from 1 to 5 mg/g.

11. A surface-treated magnesium hydroxide-comprising material according to claim 1, wherein the surface-treated magnesium hydroxide-comprising material has a moisture pick-up susceptibility to specific surface area (BET) ratio of from 0.005 to 0.4 mg/m.sup.2.

12. A surface-treated magnesium hydroxide-comprising material according to claim 1, wherein the surface-treated magnesium hydroxide-comprising material has a moisture pick-up susceptibility to specific surface area (BET) ratio of from 0.01 to 0.15 mg/m.sup.2.

13. The surface-treated magnesium hydroxide-comprising material according to claim 1 wherein the moisture content of the surface-treated magnesium hydroxide-comprising material is in the range from 0.06 to 1 wt.-% based on the total weight of the surface-treated magnesium hydroxide-comprising material.

14. The surface-treated magnesium hydroxide-comprising material according to claim 1 wherein the surface-treated magnesium hydroxide-comprising material has a top cut (d.sub.98) of <50 ?m.

15. The surface-treated magnesium hydroxide-comprising material according to claim 1 wherein the surface-treated magnesium hydroxide-comprising material has a top cut (d.sub.98) of <15 ?m.

Description

DESCRIPTION OF THE FIGURES

(1) FIG. 1 shows the evaluation of the: Normalized moisture pickup susceptibility? in function of the thermally treated and hydrophobized hydromagnesite, using surface treatment agents No. 1, No. 2 or No. 3

(2) FIG. 2 shows the SEM pictures of 1) Fresh hydromagnesite without surface treatment agent

(3) FIG. 3 shows the SEM pictures of 2) surface-treated magnesium hydroxide comprising material treated with surface treatment agent No. 1

(4) FIG. 4 shows the SEM pictures of 3) surface-treated magnesium hydroxide comprising material treated with surface treatment agent No. 2

(5) FIG. 5 shows the SEM pictures of 4) surface-treated magnesium hydroxide comprising material treated with surface treatment agent No. 3

(6) FIG. 6 shows the BET values (mg) of the magnesium carbonate-comprising material before and after calcining at different thermal treatment temperatures (?C) between 100 ?C and 900 ?C. Thevalue at 0_ mean that this sample is a freshly prepared sample at room temperature.

(7) FIG. 7 shows the correlation of the employed amount of surface treatment agent vs. the normalized water pickup in examples 8 to 13

EXAMPLES

(8) 1. Measurement Methods

(9) In the following, the measurement methods implemented in the examples are described.

(10) Humidity of Fresh Hydromagnesite

(11) A 10 g powder sample was heated in an oven at 150 ?C until the mass is constant for 15 min. The mass loss has been determined gravimetrically and is expressed as wt. % loss based on the initial sample mass. This mass loss has been attributed to the sample humidity.

(12) Particle Size Distribution (Mass % Particles with a Diameter <X) and Weight Median Diameter (d.sub.50) of a Particulate Material

(13) Weight median grain diameter and grain diameter mass distribution of a particulate material were determined using Malvern Mastersizer 3000. T his device determines the size of powders and slurries within the range of 0.1 to 900 ?m by means of laser diffraction. The analysed materials were measured in solid phase, by Aero S. For that purpose, a ca. 2 poly-spoons of dry sample is introduced into the Aero S through the corresponding sieve. The processes and instruments are known to the skilled person and are commonly used to determine grain size of fillers and pigments.

(14) Specific Surface Area BET

(15) The specific surface area is measured via the BET method according to ISO 9277:2010 using nitrogen, following conditioning of the sample by heating at 100 ?C for a period of 60 min After performing the thermal treatment of the non-upgraded pigment, the sample was directly stored in a bottom-flask containing an inert atmosphere (N.sub.2) to prevent contact with air.

(16) pH Measurements

(17) The pH of a suspension is measured at 25 ?C using a Mettler Toledo Seven Easy pH meter and a Mettler Toledo InLab.sup.+ Expert Pro pH electrode. A three point calibration (according to the segment method) of the instrument is first made using commercially available buffer solutions having pH values of 4, 7 and 10 at 20 ?C (from Aldrich). The reported pH values are the endpoint values detected by the instrument (the endpoint is when the measured signal differs by less than 0.1 mV from the average over the last 6 s).

(18) XRD Method

(19) Samples were analysed with a Bruker D8 Advance powder diffractometer obeying Bragg?s law. This diffractometer consists of a 2.2 kW X-ray tube, a sample holder, a J-J goniometer, and a V.sub.i NTEC-1 detector. Nickel-filtered Cu Ka radiation was employed in all experiments. The profiles were chart recorded automatically using a scan speed of 0.125 ? per second in 2J (XRD GV_7600). The resulting powder diffraction pattern can easily be classified by mineral content using the DIFFRAC.sup.suite software packages EVA and SEARCH, based on reference patterns of the ICDD PDF 2 database (XRD LTM_7603). Quantitative analysis of diffraction data refers to the determination of amounts of different phases in a multi-phase sample and has been performed using the DIFFRAC suite software package TOPAS (XRD LTM_7604). In detail, quantitative analysis allows to determine structural characteristics and phase proportions with quantifiable numerical precision from the experimental data itself. This involves modelling the full diffraction pattern (Rietveld approach) such that the calculated pattern(s) duplicates the experimental one. The Rietveld method requires knowledge of the approximate crystal structure of all phases of interest in the pattern. However, the use of the whole pattern rather than a few select lines produces accuracy and precision much better than any single-peak-intensity based method.

(20) Moisture Pick Up Susceptibility

(21) The moisture pickup susceptibility of a material as referred to herein, is determined in mg moisture/g of solid, after exposure to an atmosphere of 10 and 85% relative humidity, respectively, for 2 hours at a temperature of +23 ?C (? 2 ?C). For this purpose, the sample is first kept at an atmosphere of 10% relative humidity for 2 hours, then the atmosphere is changed to 85% relative humidity at which the sample is kept for another 2 hours, finally the atmosphere is changed to 10% of humidity for 30 minutes.

(22) The weight increase is then used to calculate the moisture pick-up in mg moisture/g of sample.

(23) The moisture pick up susceptibility in mg/g divided by the specific surface area in mg (calculated based on the specific surface area BET) corresponds to the normalized moisture pick up susceptibility_ expressed in mg/m of sample.

(24) Scanning Electron Microscope (SEM)

(25) The prepared samples were examined by a Sigma VP field emission scanning electron microscope (Carl Zeiss AG, Germany) and a variable pressure secondary electron detector (VPSE) and/or secondary electron detector (SE) with a chamber pressure of about 50 Pa.

(26) 2. Starting Materials

(27) 2.1. Surface Treatment Agents

(28) TABLE-US-00001 TABLE 1 Surface treatment agents Surface treatment agent number Name Supplier Properties (1) n-Octadecyltriethoxy- Gelest Purity >95%; silane (CAS: 7399-00-0) order number Refractive Index: SIO6642.0 1.4386; Melting Point: 10-12?C; Flash Point: <150?C (2) 1H,1H,2H,2H- Sigma-Aldrich Purity: 97%; Perfluorodecyltriethoxy- order number Refractive Index: silane 97% (CAS: CDS010752- 1.342; 101947-16-4) 250 mg Boiling Point: 209-230?C; Flash Point: >110?C (3) 1H,1H,2H,2H- Aldrich Purity: 98%; Perfluorooctyltriethoxy- order number Refractive Index: silane (CAS: 51851-37-7) MK BX 9419V 1.344; Flash Point: 97?C
2.2. Mineral Pigments

(29) TABLE-US-00002 TABLE 2 Mineral pigment Normalized Moisture moisture BET pick up pick up surface susceptibility susceptibility d.sub.50 Humidity Chemical nature [m.sup.2/g] (mg/g) (mg/m.sup.2) [lm] [wt.-%] Hydromagnesite 62.07 57.46 0.92 5.26 3.51 (Used abbreviation in the text: HMG)
3. Experiments

Example 1 (Comparative)

(30) 8 g of fresh HMG (dried at 100 ?C overnight) was putted in a 250 mL beaker, then 54 g of distilled water was added. The slurry was heated up-to 90 ?C, the system was kept under reflux to prevent the evaporation of the used solvent. In parallel, 0.34 g of the surface treatment agent No. 1, corresponding to a 0.0056 g/m.sup.2, was added in a 50 mL container to 3.20 g of Ethanol/H.sub.2O mixture of 1-to-1 ratio. The latter solution was heated up to 70 ?C, then 530 .Math.L of a 10 wt.-% solution of KOH was added, the mixture was kept for 6 minutes. Finally, the solution containing the surface treatment agent No. 1 was added to the slurry and left under mixing for 30 minutes. The upgraded slurry was next filtrated under vacuum using cellulose based filters of (Whatman Rundfilter Art. Nr. 9060202, 90 mm, 589/2 No. 1 & 2). The filter cake was dried overnight at 110 ?C, then deagglomerated manually using a mortar and a pestle.

Example 2 (Comparative)

(31) 8 g of fresh HMG (dried at 100 ?C overnight) was thermally treated at 300 ?C for 2 hours, then putted in a 250 mL beaker with 54 g of distilled water. The slurry was heated up-to 90 ?C, the system was kept under reflux to prevent the evaporation of the used solvent. In parallel, 0.40 g of the surface treatment agent No. 1, corresponding to a 0.0056 g/m.sup.2, was added in a 50 mL container to 3.70 g of Ethanol/H.sub.2O mixture of 1-to-1 ratio. The latter solution was heated up to 70 ?C, then 615 .Math.L of a 10 wt.-% solution of KOH was added, the mixture was kept for 6 minutes. Finally, the solution containing the surface treatment agent No. 1 was added to the slurry and left under mixing for 30 min. The upgraded slurry was next filtrated under vacuum using cellulose based filters of (Whatman Rundfilter Art. Nr. 9060202, 90 mm, 589/2 No. 1 & 2). The filter cake was dried overnight at 110 ?C, then deagglomerated manually using a mortar and a pestle.

Example 3 (Comparative)

(32) 8 g of fresh HMG (dried at 100 ?C overnight) was thermally treated at 400 ?C for 2 hours, then putted in a 250 mL beaker with 54 g of distilled water. The slurry was heated up-to 90 ?C, the system was kept under reflux to prevent the evaporation of the used solvent. In parallel, 1.62 g of the surface treatment agent No. 1, corresponding to a 0.0056 g/m.sup.2, was added in a 50 mL container to 14.70 g of Ethanol/H.sub.2O mixture of 1-to-1 ratio. The latter solution was heated up to 70 ?C, then 2.47 mL of a 10 wt.-% solution of KOH was added, the mixture was kept for 6 minutes. Finally, the solution containing the surface treatment agent No. 1 was added to the slurry and left under mixing for 30 min. The upgraded slurry was next filtrated under vacuum using cellulose based filters of (Whatman Rundfilter Art. Nr. 9060202, 90 mm, 589/2 No. 1 & 2). The filter cake was dried overnight at 110 ?C, then deagglomerated manually using a mortar and a pestle.

Example 4 (Inventive)

(33) 8 g of fresh HMG (dried at 100 ? overnight) was thermally treated at 600 ?C for 2 hours, then putted in a 250 mL beaker with 54 g of distilled water. The slurry was heated up-to 90 ?C, the system was kept under reflux to prevent the evaporation of the used solvent. In parallel, 0.68 g of the surface treatment agent No. 1, corresponding to a 0.0056 g/m.sup.2, was added in a 50 mL container to 6.30 g of Ethanol/H.sub.2O mixture of 1-to-1 ratio. The latter solution was heated up to 70 ?C, then 1.05 mL of a 10 wt.-% solution of KOH was added, the mixture was kept for 6 minutes. Finally, the solution containing the surface treatment agent No. 1 was added to the slurry and left under mixing for 30 min. The upgraded slurry was next filtrated under vacuum using cellulose based filters of (Whatman Rundfilter Art. Nr. 9060202, 90 mm, 589/2 No. 1 & 2). The filter cake was dried overnight at 110 ?C, then deagglomerated manually using a mortar and a pestle.

Example 5 (Comparative)

(34) 8 g of fresh HMG (dried at 100 ?C overnight) was thermally treated at 900 ?C for 2 hours, then putted in a 250 mL beaker with 54 g of distilled water. The slurry was heated up-to 90 ?C, the system was kept under reflux to prevent the evaporation of the used solvent. In parallel, 0.23 g of the surface treatment agent No. 1, corresponding to a 0.0056 g/m.sup.2, was added in a 50 mL container to 2.10 g of Ethanol/H.sub.2O mixture of 1-to-1 ratio. The latter solution was heated up to 70 ?C, then 350 .Math.L of a 10 wt.-% solution of KOH was added, the mixture was kept for 6 min. Finally, the solution containing the surface treatment agent No. 1 was added to the slurry and left under mixing for 30 min. The upgraded slurry was next filtrated under vacuum using cellulose based filters of (Whatman Rundfilter Art. Nr. 9060202, 90 mm, 589/2 No. 1 & 2). The filter cake was dried overnight at 110 ?C, then deagglomerated manually using a mortar and a pestle.

Example 6 (Inventive)

(35) 8 g of fresh HMG (dried at 100 ?C overnight) was thermally treated at 600 ?C for 2 hours, then putted in a 250 mL beaker with 54 g of distilled water. The slurry was heated up-to 90 ?C, the system was kept under reflux to prevent the evaporation of the used solvent. In parallel, 1.02 g of the surface treatment agent No. 2, corresponding to an iso-molar value of the surface treatment agent No. 1 in the Example 4, was added in a 50 mL container to 9.33 g of Ethanol/H.sub.2O mixture of 1-to-1 ratio. The latter solution was heated up to 70 ?C, then 480 .Math.L of a 10 wt.-% solution of KOH was added, the mixture was kept for 6 min. Finally, the solution containing the surface treatment agent No. 2 was added to the slurry and left under mixing for 30 min. The upgraded slurry was next filtrated under vacuum using cellulose based filters of (Whatman Rundfilter Art. Nr. 9060202, 90 mm, 589/2 No. 1 & 2). The filter cake was dried overnight at 110 ?C, then deagglomerated manually using a mortar and a pestle.

Example 7 (Inventive)

(36) 8 g of fresh HMG (dried at 100 ?C overnight) was thermally treated at 600 ?C for 2 hours, then putted in a 250 mL beaker with 54 g of distilled water. The slurry was heated up-to 90 ?C, the system was kept under reflux to prevent the evaporation of the used solvent. In parallel, 0.87 g of the surface treatment agent No. 3, corresponding to an iso-molar value of the surface treatment agent No. 1 in the Example 4, was added in a 50 mL container to 7.96 g of Ethanol/H.sub.2O mixture of 1-to-1 ratio. The latter solution was heated up to 70 ?C, then 480 .Math.L of a 10 wt.-% solution of KOH was added, the mixture was kept for 6 min. Finally, the solution containing the surface treatment agent No. 2 was added to the slurry and left under mixing for 30 min. The upgraded slurry was next filtrated under vacuum using cellulose based filters of (Whatman Rundfilter Art. Nr. 9060202, 90 mm, 589/2 No. 1 & 2). The filter cake was dried overnight at 110 ?C, then deagglomerated manually using a mortar and a pestle.

Example 8 (Comparative)

(37) 8 g of fresh HMG (dried at 100 ?C overnight) was thermally treated at 600 ?C for 2 hours, then putted in a 250 mL beaker with 54 g of distilled water. The slurry was heated up-to 90 ?C, the system was kept under reflux to prevent the evaporation of the used solvent. Finally, the slurry was filtrated under vacuum using cellulose based filters of (Whatman Rundfilter Art. Nr. 9060202, 90 mm, 589/2 No. 1 & 2). The filter cake was dried overnight at 110 ?C, then deagglomerated manually using a mortar and a pestle.

Example 9 (Comparative)

(38) 8 g of fresh HMG (dried at 100 ?C overnight) was thermally treated at 600 ?C for 2 hours, then putted in a 250 mL beaker with 54 g of distilled water. The slurry was heated up-to 90 ?C, the system was kept under reflux to prevent the evaporation of the used solvent. In parallel, 0.11 g of the surface treatment agent No. 1, corresponding to a 0.09 mg/m.sup.2, was added in a 50 mL container to 1.1 g of Ethanol/H.sub.2O mixture of 1-to-1 ratio. The latter solution was heated up to 70 ?C, then 17.6 .Math.L of a 10 wt.-% solution of KOH was added, the mixture was kept for 6 minutes. Finally, the solution containing the surface treatment agent No. 1 was added to the slurry and left under mixing for 30 min. The upgraded slurry was next filtrated under vacuum using cellulose based filters of (Whatman Rundfilter Art. Nr. 9060202, 90 mm, 589/2 No. 1 & 2). The filter cake was dried overnight at 110 ?C, then deagglomerated manually using a mortar and a pestle.

Example 10 (Comparative)

(39) 8 g of fresh HMG (dried at 100 ?C overnight) was thermally treated at 600 ?C for 2 hours, then putted in a 250 mL beaker with 54 g of distilled water. The slurry was heated up-to 90 ?C, the system was kept under reflux to prevent the evaporation of the used solvent. In parallel, 0.13 g of the surface treatment agent No. 1, corresponding to a 0.11 mg/m.sup.2, was added in a 50 mL container to 1.1 g of Ethanol/H.sub.2O mixture of 1-to-1 ratio. The latter solution was heated up to 70 ?C, then 17.6 .Math.L of a 10 wt.-% solution of KOH was added, the mixture was kept for 6 minutes. Finally, the solution containing the surface treatment agent No. 1 was added to the slurry and left under mixing for 30 min. The upgraded slurry was next filtrated under vacuum using cellulose based filters of (Whatman Rundfilter Art. Nr. 9060202, 90 mm, 589/2 No. 1 & 2). The filter cake was dried overnight at 110 ?C, then deagglomerated manually using a mortar and a pestle.

Example 11 (Comparative)

(40) 8 g of fresh HMG (dried at 100 ?C overnight) was thermally treated at 600 ?C for 2 hours, then putted in a 250 mL beaker with 54 g of distilled water. The slurry was heated up-to 90 ?C, the system was kept under reflux to prevent the evaporation of the used solvent. In parallel, 0.23 g of the surface treatment agent No. 1, corresponding to a 1.99 mg/m.sup.2, was added in a 50 mL container to 2.1 g of Ethanol/H.sub.2O mixture of 1-to-1 ratio. The latter solution was heated up to 70 ?C, then 350 .Math.L of a 10 wt.-% solution of KOH was added, the mixture was kept for 6 minutes. Finally, the solution containing the surface treatment agent No. 1 was added to the slurry and left under mixing for 30 min. The upgraded slurry was next filtrated under vacuum using cellulose based filters of (Whatman Rundfilter Art. Nr. 9060202, 90 mm, 589/2 No. 1 & 2). The filter cake was dried overnight at 110 ?C, then deagglomerated manually using a mortar and a pestle.

Example 12 (Comparative)

(41) 8 g of fresh HMG (dried at 100 ?C overnight) was thermally treated at 600 ? for 2 hours, then putted in a 250 mL beaker with 54 g of distilled water. The slurry was heated up-to 90 ?C, the system was kept under reflux to prevent the evaporation of the used solvent. In parallel, 0.92 g of the surface treatment agent No. 1, corresponding to a 7.99 mg/m.sup.2, was added in a 50 mL container to 8.4 g of Ethanol/H.sub.2O mixture of 1-to-1 ratio. The latter solution was heated up to 70 ?C, then 1410 .Math.L of a 10 wt.-% solution of KOH was added, the mixture was kept for 6 minutes. Finally, the solution containing the surface treatment agent No. 1 was added to the slurry and left under mixing for 30 min. The upgraded slurry was next filtrated under vacuum using cellulose based filters of (Whatman Rundfilter Art. Nr. 9060202, 90 mm, 589/2 No. 1 & 2). The filter cake was dried overnight at 110 ?C, then deagglomerated manually using a mortar and a pestle.

Example 13 (Comparative)

(42) 8 g of fresh HMG (dried at 100 ?C overnight) was thermally treated at 600 ?C for 2 hours, then putted in a 250 mL beaker with 54 g of distilled water. The slurry was heated up-to 90 ?C, the system was kept under reflux to prevent the evaporation of the used solvent. In parallel, 2.07 g of the surface treatment agent No. 1, corresponding to a 17.99 mg/m.sup.2, was added in a 50 mL container to 18.9 g of Ethanol/H.sub.2O mixture of 1-to-1 ratio. The latter solution was heated up to 70 ?C, then 3170 .Math.L of a 10 wt.-% solution of KOH was added, the mixture was kept for 6 minutes. Finally, the solution containing the surface treatment agent No. 1 was added to the slurry and left under mixing for 30 min. The upgraded slurry was next filtrated under vacuum using cellulose based filters of (Whatman Rundfilter Art. Nr. 9060202, 90 mm, 589/2 No. 1 & 2). The filter cake was dried overnight at 110 ?C, then deagglomerated manually using a mortar and a pestle.

(43) TABLE-US-00003 TABLE 3 Summary and results. Thermal Base for BET of the Normalized treatment Surface hydrolysing surface Moisture Moisture temperature Surface treatment surface treated pick up pick up Mineral (T? C.) for 2 treatment agent treatment HMG susceptibility susceptibility d.sub.50 Example pigment hours agent No. dosage .sup.a) agent (m.sup.2/g) (mg/g) (mg/m.sup.2) (?m) 1 (comparative) HMG 1 5.6 KOH 52.39 45.13 0.86 5.26 2 (comparative) HMG 300 1 5.6 KOH 63.96 57.32 0.89 3 (comparative) HMG 400 1 5.6 KOH 57.08 66.08 1.15 4 (inventive) HMG 600 1 5.6 KOH 36.90 3.60 0.09 3.75 5 (comparative) HMG 900 1 5.6 KOH 19.15 4.98 0.25 6 (inventive) HMG 600 2 .sup.b) KOH 41.53 3.01 0.072 4.59 7 (inventive) HMG 600 3 .sup.b) KOH 52.49 3.22 0.061 1.98 8 (Comparative) HMG 600 60.50 32.19 0.53 9 (Comparative) HMG 600 1 0.09 KOH 68.43 30.71 0.448 10 (Comparative) HMG 600 1 0.11 KOH 41.62 18.36 0.441 11 (Comparative) HMG 600 1 1.99 KOH 56.11 18.03 0.32 12 (Comparative) HMG 600 1 7.99 KOH 52.46 8.84 0.17 13 (Comparative) HMG 600 1 17.99 KOH 26.11 13.75 0.52 .sup.a) Ratio: Surface treatment agent (mg)/BET of the thermally treated but non-upgraded HMG (m.sup.2/g); .sup.b) The amount of surface treatment agent No. 2 and No. 3 was calculated based on an iso-molar value calculated from the Example 4.

(44) TABLE-US-00004 TABLE 4 Concentration of the surface treatment agent in ethanol/water mixture in the examples. Surface treatment Example agent [g] Ethanol/Water [g] concentration 1 0.34 3.2 0.11 2 0.4 3.7 0.11 3 1.62 14.7 0.11 4 0.68 6.3 0.11 5 0.23 2.1 0.11 6 1.02 9.33 0.11 7 0.87 7.96 0.11 9 0.11 1.1 0.10 10 0.13 1.1 0.12 11 0.23 2.1 0.11 12 0.92 8.4 0.11 13 2.07 18.9 0.11

(45) As can be seen from table 4 in all the examples nearly the same concentration of surface treatment agent in ethanol/water mixture has been used.

(46) The data of examples 4, 6 and 7 (Table 3) show that the surface-treated magnesium hydroxide comprising material has a large surface area in combination with a low moisture pick up susceptibility when the process according to the present invention is used.

(47) As can be seen in Table 3 as well as from FIG. 1 the surface-treated magnesium hydroxide-comprising materials that have been prepared by the inventive process have a normalized moisture pick up susceptibility of between 0.061 to 0.09 m Contrary to that, surface-treated magnesium hydroxide-comprising materials that have been prepared with the same surface treatment agent than used in example 4 but have been calcined at temperatures below 450 ?C or above 750 ?C have much higher normalized moisture pickup susceptibilities of between 0.25 to 1.15 m

(48) Therefore, it has been shown that it is possible to prepare a surface-treated magnesium hydroxide-comprising material by the inventive process that has a large surface area in combination with a low moisture pick up susceptibility.