SURFACE MODIFIED LAYERED DOUBLE HYDROXIDE

Abstract

Processes for making surface-modified layered double hydroxides (LDHs) are disclosed, as well as surface-modified LDHs, and their uses in composite materials. The surface-modified LDHs of the invention are more hydrophobic than their unmodified analogues, which allows the surface-modified LDHs to be incorporated in a wide variety of materials, wherein the interesting functionality of LDHs may be exploited.

Claims

1. A process for forming a modified layered double hydroxide comprising the steps of: a) providing a layered double hydroxide; b) heating the layered double hydroxide to 110-200° C.; and c) mixing the thermally-treated layered double hydroxide of step b) with a modifier, wherein the mixing is conducted in the presence of less than or equal to 50% by weight of a solvent, relative to the total weight of the layered double hydroxide and the modifier.

2. The process according to claim 1, wherein the modifier is selected from the group consisting of fatty acids, fatty acid salts, sulfate modifiers, phosphonate modifiers, phthalate modifiers and organosilane modifiers.

3. The process according to claim 2, wherein the modifier is selected from the group consisting of: stearic acid, lauric acid, palmitic acid, arachidic acid, maleic acid and oleic acid; metal salts of stearic acid, lauric acid, palmitic acid, arachidic acid, maleic acid and oleic acid; sodium dodecyl sulfate; sodium octadecyl phosphonate; dioctyl terephthalate, diisodecyl phthalate, diisononyl phthalate, dioctyl phthalate and dibutyl phthalate; and trimethoxypropylsilane, trimethoxyoctylsilane, (3-glycidyloxypropyl)-trimethoxysilane and (3-aminopropyl)triethoxysilane.

4. The process according to claim 3, wherein the modifier is lithium stearate, zinc stearate, magnesium stearate, calcium stearate or sodium stearate.

5. The process according to claim 4, wherein the modifier is zinc stearate.

6. The process according to claim 1, wherein the layered double hydroxide provided in step a) is of formula (TB):
[M.sup.z+.sub.1-xM′.sup.y+.sub.x(OH).sub.2].sup.a+(X.sup.n−).sub.m.bH.sub.2O.c(L)   (TB) wherein M is at least one charged metal cation; M′ is at least one charged metal cation different from M; z is 1 or 2; y is 3 or 4; 0<x<0.9; 0<b≤10; 0<c≤10; X is at least one anion; n is the charge on anion(s) X; a is equal to z(1−x)+xy−2; m≥a/n; and L is an organic solvent capable of hydrogen-bonding to water.

7. The process according to claim 1, wherein the layered double hydroxide is a Zn/Al, Mg/Al, Mg,Zn/Al, Mg/Al,Sn, Ca/Al, Ni/Ti or Cu/Al layered double hydroxide.

8. The process according to claim 6, wherein X is an anion selected from at least one of halide, inorganic oxyanion, and an organic anion (e.g. an anionic surfactant, an anionic chromophore or an anionic UV absorber).

9. The process according to claim 8, wherein the inorganic oxyanion is carbonate, bicarbonate, hydrogenphosphate, dihydrogenphosphate, nitrite, borate, nitrate, sulphate or phosphate or a mixture of two or more thereof.

10. The process according to claim 1, wherein in step b) the layered double hydroxide is heated to 130-180° C.

11. The process according to claim 1, wherein in step c) the mixing is conducted in the presence of less than or equal to 10% by weight of a solvent, relative to the total weight of the layered double hydroxide and the modifier.

12. The process according to claim 1, wherein the quantity of the modifier used in step c) is 1-25% by weight relative to the weight of the layered double hydroxide.

13. The process according to claim 1, wherein in step c) the mixing takes place at 60-270° C.

14. A modified layer double hydroxide obtainable by a process according to claim 1.

15. A composite material comprising a modified layer double hydroxide according to claim 14, dispersed throughout a polymer.

Description

EXAMPLES

[0283] Embodiments of the invention will now be described, for the purpose of illustration only, with reference to the accompanying figures, in which:

[0284] FIG. 1 shows the Differential Thermal Analysis scan of Zn.sub.2MgAl—CO.sub.3 LDH between 20° C. and 800° C.

[0285] FIG. 2 shows the percentage water uptake of Examples 14, 17, 18 and 19 at various time points after exposure to RH60 at 25° C.

[0286] FIG. 3 shows overlaid Differential Thermal Analysis scans of Zn.sub.2MgAl—CO.sub.3 LDH samples (Example 14 and Examples 16-19) between 20° C. and 800° C.

[0287] FIG. 4 shows the percentage water uptake of Examples 6 and 7 at various time points after exposure to RH60 at 25° C.

[0288] FIG. 5 shows the percentage water uptake at various time points after exposure to RH60 at 25° C. of Examples 17, 18 and Zn.sub.2MgAl—CO.sub.3 LDH samples (AMO treated; prepared according to method 2.2) modified with various loadings of zinc stearate at 110° C.

[0289] FIG. 6 shows pictures of the water/oil compatibility tests carried out on unmodified Zn.sub.2MgAl—CO.sub.3 LDH (Example 14) and Zn.sub.2MgAl—CO.sub.3 LDH modified with various amounts of stearic acid (Examples 20-22) or zinc stearate (Examples 15-18).

[0290] FIG. 7 shows overlaid X-Ray Diffractograms for unmodified Zn.sub.2MgAl—CO.sub.3 LDH (Example 6) and Zn.sub.2MgAl—CO.sub.3 LDH modified with 7% zinc stearate (Example 7).

[0291] FIG. 8 shows the percentage water uptake of Examples 74, 76 and 75 at various time points after exposure to RH60 at 25° C.

[0292] FIG. 9 shows the percentage water uptake of Examples 85, 86 and 87 at various time points after exposure to RH60 at 25° C.

[0293] FIG. 10 shows the percentage water uptake of Examples 74, 88 and 89 at various time points after exposure to RH60 at 25° C.

[0294] The abbreviations used in the below examples and tables have the following meanings:

Mg.sub.3Al—CO.sub.3: [Mg.sub.0.75Al.sub.0.25(OH).sub.2][CO.sub.3].sub.0.125.bH.sub.2O;
Zn.sub.2MgAl—CO.sub.3: [(Mg.sub.0.33Zn.sub.0.66).sub.0.75Al.sub.0.25(OH).sub.2][CO.sub.3].sub.0.125.bH.sub.2O.
Zn.sub.2Al—NO.sub.3: [Zn.sub.0.66Al.sub.0.33(OH).sub.2][NO.sub.3].sub.0.31.bH.sub.2O.
Zn.sub.2Al—PO.sub.4: [Zn.sub.0.66Al.sub.0.33(OH).sub.2][PO.sub.4].sub.0.10.bH.sub.2O.
Zn.sub.2Al—BO.sub.3: [Zn.sub.0.66Al.sub.0.33(OH).sub.2][BO.sub.3].sub.0.31.bH.sub.2O.

Part I Example 1—Preparation of LDHs (Mg.SUB.3.Al—Co.SUB.3.)

Method 1.1

[0295] Mg(NO.sub.3).sub.2.6H.sub.2O (11.535 kg) and Al(NO.sub.3).sub.3.9H.sub.2O (5.624 kg) were dissolved in 42 L of deionized water (Solution A). A second solution was made containing Na.sub.2CO.sub.3 (3.18 kg) and NaOH (3.84 kg) dissolved in 42 L of deionized water (Solution B). Solutions A and B were added together through mixing machine at the speed of 2,900 rpm and transfer to aging tank under a stirring speed of 40 rpm at 100° C. for 4 hours. The pH was controlled at 10. After 4 hours of ageing, the resulting slurry was filtered by filter press technique, the filter cake was washed with deionized water the pH of the washings was 7, dried by vacuum oven at 110° C. for 18 hours and ground to a powder.

Method 1.2

[0296] A metal precursor solution was prepared by dissolving the Mg(NO.sub.3).sub.2.6H.sub.2O (4.904 kg) and Al(NO.sub.3).sub.3.9H.sub.2O (2.391 kg) in 8.5 L of deionized water. The metal precursor solution was added drop-wise with a drop rate of 645 ml/minute into 8.5 L of a 1.5 M Na.sub.2CO.sub.3 solution under a stirring speed of 800 rpm at room temperature. The system was kept at a constant pH 10 by using a 12 M NaOH solution. After 4 hours of ageing, the resulting slurry was filtered under vacuum, and the filter cake was washed with deionized water the pH of the washings was 7. The solid was then dried in a vacuum oven at 110° C. for 18 hours and ground to a powder.

Example 2—Preparation of LDHs (Zn.SUB.2.MgAl—Co.SUB.3.)

Method 2.1

[0297] Zn(NO.sub.3).sub.2.6H.sub.2O (8.919 kg), Mg(NO.sub.3).sub.2.6H.sub.2O (3.845 kg) and Al(NO.sub.3).sub.3.9H.sub.2O (5.624 kg) were dissolved in 42 L of deionized water (Solution A). A second solution was made containing Na.sub.2CO.sub.3 (3.18 kg) and NaOH (3.84 kg) dissolved in 42 L of deionized water (Solution B). Solutions A and B were added together through mixing machine at the speed of 2,900 rpm and transfer to aging tank under a stirring speed of 40 rpm at 100° C. for 4 hours. The pH was controlled at 10. After 4 hours of ageing, the resulting slurry was filtered by filter press technique, the filter cake was washed with deionized water the pH of the washings was 7, dried by vacuum oven at 110° C. for 18 hours and ground to a powder.

Method 2.2

[0298] A metal precursor solution was prepared by dissolving Zn(NO.sub.3).sub.2.6H.sub.2O (3.793 kg), Mg(NO.sub.3).sub.2.6H.sub.2O (1.635 kg) and Al(NO.sub.3).sub.3.9H.sub.2O (2.391 kg) in 8.5 L of deionized water. The metal precursor solution was added drop-wise with a drop rate of 645 ml/minute into 8.5 L of a 1.5 M Na.sub.2CO.sub.3 solution under a stirring speed of 800 rpm at room temperature. The system was kept at a constant pH 10 by using a 12 M NaOH solution. After 4 hours of ageing, the resulting slurry was filtered under vacuum, and the filter cake was washed with deionized water the pH of the washings was 7. The solid was then dried in a vacuum oven at 110° C. for 18 hours and ground to a powder.

Example 3—Preparation of AMO-LDHs

[0299] LDHs were prepared according to the methods described in Example 1 or Example 2, with the exception that after water washing of the filter cake, and prior to vacuum oven drying, the water-wet LDH was re-dispersed in ethanol for 1 hour at a stirring speed of 40 rpm and then filtered by vacuum filtration technique.

Example 4—Modification of LDHs/AMO-LDHs with Zinc Stearate/Stearic Acid

Example 4.1—Zinc Stearate

[0300] LDHs or AMO-LDHs prepared according to the methods described in Examples 1 to 3, were heated at 150° C. for 4 hours and then mixed with zinc stearate (for amounts see Table 1) at a mixing speed of 600 rpm and a temperature of 150° C. for 30 minutes to obtain modified LDH.

Example 4.2—Stearic Acid

[0301] LDHs or AMO-LDHs prepared according to the methods described in Examples 1 to 3, were heated at 150° C. for 4 hours and then mixed with stearic acid (for amounts see Table 1) at a mixing speed of 600 rpm and a temperature of 100° C. for 30 minutes to obtain modified LDH.

Example 5—Modification of LDHs/AMO-LDHs with Phthalate Modifiers

[0302] LDHs or AMO-LDHs prepared according to the methods described in Examples 1 to 3, were heated at 150° C. for 4 hours and then mixed with either dioctyl terephthalate—DOTP, diisodecyl phthalate—DIDP, diisononyl phthalate—DINP, dioctyl phthalate—DOP, or dibutyl phthalate—DBP (7% w/w loading; equivalent to 7 g of modifier per 100 g of LDH powder) at a mixing speed of 600 rpm and a temperature of 100° C. for 30 minutes to obtain modified LDH.

TABLE-US-00001 TABLE 1 Modifier AMO Loading Example LDH Method treated? Modifier (% w/w) 6 Zn.sub.2MgAl—CO.sub.3 2.1 No None — 7 Zn.sub.2MgAl—CO.sub.3 2.1 No Zinc 7 stearate 8 Zn.sub.2MgAl—CO.sub.3 2.1 No Zinc 10 stearate 9 Zn.sub.2MgAl—CO.sub.3 2.1 No Zinc 15 stearate 10 Zn.sub.2MgAl—CO.sub.3 2.1 Yes None — 11 Zn.sub.2MgAl—CO.sub.3 2.1 Yes Zinc 7 stearate 12 Zn.sub.2MgAl—CO.sub.3 2.1 Yes Zinc 10 stearate 13 Zn.sub.2MgAl—CO.sub.3 2.1 Yes Zinc 15 stearate 14 Zn.sub.2MgAl—CO.sub.3 2.2 Yes None — 15 Zn.sub.2MgAl—CO.sub.3 2.2 Yes Zinc 3 stearate 16 Zn.sub.2MgAl—CO.sub.3 2.2 Yes Zinc 5 stearate 17 Zn.sub.2MgAl—CO.sub.3 2.2 Yes Zinc 7 stearate 18 Zn.sub.2MgAl—CO.sub.3 2.2 Yes Zinc 10 stearate 19 Zn.sub.2MgAl—CO.sub.3 2.2 Yes Zinc 15 stearate 20 Zn.sub.2MgAl—CO.sub.3 2.2 Yes Stearic 3 acid 21 Zn.sub.2MgAl—CO.sub.3 2.2 Yes Stearic 5 acid 22 Zn.sub.2MgAl—CO.sub.3 2.2 Yes Stearic 10 acid 23 Mg.sub.3Al—CO.sub.3 1.1 No None — 24 Mg.sub.3Al—CO.sub.3 1.1 No Zinc 7 stearate 25 Mg.sub.3Al—CO.sub.3 1.1 No Zinc 10 stearate 26 Mg.sub.3Al—CO.sub.3 1.1 No Zinc 15 stearate 27 Mg.sub.3Al—CO.sub.3 1.1 Yes None — 28 Mg.sub.3Al—CO.sub.3 1.1 Yes Zinc 7 stearate 29 Mg.sub.3Al—CO.sub.3 1.1 Yes Zinc 10 stearate 30 Mg.sub.3Al—CO.sub.3 1.1 Yes Zinc 15 stearate 31 Mg.sub.3Al—CO.sub.3 1.2 No None — 32 Mg.sub.3Al—CO.sub.s 1.2 No Zinc 15 stearate 33 Mg.sub.2Al—CO.sub.3.sup.a — No None — 34 Mg.sub.2Al—CO.sub.3.sup.a — No Zinc 7 stearate 35 Mg.sub.2Al—CO.sub.3.sup.a — No Zinc 15 stearate 36 Zn.sub.2MgAl—CO.sub.3 2.2 No DOTP 1 37 Zn.sub.2MgAl—CO.sub.3 2.2 No DBP 7 38 Zn.sub.2MgAl—CO.sub.3 2.2 No DOP 7 39 Zn.sub.2MgAl—CO.sub.3 2.2 No DIDP 7 40 Zn.sub.2MgAl—CO.sub.3 2.2 No DINP 7 .sup.aMg.sub.2Al—CO.sub.3 obtained from commercial source

Scale-Up of LDH/AMO-LDH Modification

[0303] The modifications according to Examples 4 & 5 were carried out on a 5-15 g scale in round-bottomed flasks. The zinc stearate modifications of Zn.sub.2MgAl—CO.sub.3 were repeated on (i) a 1 kg scale using an internal mixer at a speed of 800 rpm at 150° C. for 30 min, and on (ii) a 5-10 kg scale in a Labo powder mixer at a speed of 1200 rpm at 150° C. for 30 min.

Characterisation of Modified LDHs

Density Measurements

[0304] Samples were heated at 110° C. for at least 3 hr to remove any excess moisture and then stored in a desiccator prior to density measurement. Sample was added to a pre-weighed 100 ml measuring cylinder, to a volume of 100 ml and then the mass of the cylinder+sample was weighed. The mass of the sample was determined by subtracting the mass of the cylinder. Bulk density (g/ml) was calculated as:

Bulk density=mass of sample (g)/100 (ml).

[0305] The measuring cylinder containing sample was then placed in an AutoTap machine (Quantachrome, Model AT-6-220-50) and subjected to tapping to reduce the volume. The tapped density (g/ml) was calculated as:

Tapped density=mass of sample (g)/volume of sample after tapping (ml).

Moisture Uptake Capacity

[0306] Pre-weighed samples were exposed at 60% (+/−5%) relative humidity, 20° C. The percentage weight change for samples after an exposure time T were calculated by:

% weight change=(wt after exposure (T mins)−wt pre-exposure)×100.

Hydrophobicity

Method A: Water/Oil Compatibility

[0307] Samples were added into a mixture of 200 ml of water/20 ml of 1-hexene. FIG. 6 shows exemplary water/oil compatibility tests. The compatibility of LDH sample in 1-hexene was evaluated by eye; good compatibility in the oil phase correlated with the sample being predominantly present in that phase; poor compatibility correlated with the sample being predominantly present in the aqueous phase.

Method B: Contact Angle Measurement

[0308] LDH samples were prepared as flat pellets with 2 cm diameter. A water droplet (10 μl) was injected by Teflon type syringe and dropped onto the LDH pellet surface. The contact angle of the water droplet on the pellet surface was measured by Contact Angle Meter DM-701 (FAMAS). Triplet measurements were made and the average of the three measurements taken.

TABLE-US-00002 TABLE 2 Bulk Tapped Surface Average density density area Oil phase Contact Example (g/ml) (g/ml) (m.sup.2/g) compatibility Angle (°) 6 0.39 0.61 37.7 Poor 18.0 7 0.50 0.74 36.3 Good 122 8 0.53 0.79 23.7 Good 132 9 0.55 0.78 27.0 Good 123 10 0.32 0.44 70.6 Poor 17.9 11 0.32 0.50 53.3 Good 123 12 0.33 0.52 47.6 Good 126 13 0.35 0.55 39.9 Good 125 14 0.16 0.23 84.9 Poor 23.2 15 — — — Good — 16 0.19 — 75.4 Good 104 17 0.20 — 54.7 Good 106 13 0.21 — 58.9 Good 108 19 0.25 0.33 64.8 Good 109 20 — — — Partial — 21 — — — Good — 22 — — — Good — 23 0.46 0.69 77 Poor — 24 0.61 0.92 53 Good — 25 0.65 0.91 — Good — 26 0.71 0.94 35 Good — 27 0.28 0.46 105 Poor — 28 0.33 0.57 94 Good — 29 0.35 0.58 — Good — 30 0.34 0.60 76 Good — 31 0.41 0.62 68.4 Poor — 32 0.52 0.84 35.1 Good — 33 0.35 0.52 20.4 Poor 106 34 0.43 0.68 15.6 Good 113 35 0.42 0.73 8.8 Good 121 36 — — — — 104 37 — — — — 104 38 — — — — 115 39 — — — — 116 40 — — — — 132

[0309] For a given LDH, the data in Table 2 shows that surface modification was generally found to increase the bulk and tapped densities, reduce the surface area and increase the hydrophobicity as seen by improved oil phase compatibility and increased average contact angle.

[0310] FIG. 2 shows the moisture uptake capacity at 60% RH, 25° C. for Examples 14 (Zn.sub.2MgAl—CO.sub.3; 0% Zn stearate), 17 (Zn.sub.2MgAl—CO.sub.3; 7% Zn stearate), 18 (Zn.sub.2MgAl—CO.sub.3; 10% Zn stearate) and 19 (Zn.sub.2MgAl—CO.sub.3; 15% Zn stearate) measured over 180 minutes. With increasing zinc stearate loading, the moisture uptake capacity is reduced from 8% for the unmodified LDH, to 0.5% for the modified LDH with a 15% loading of zinc stearate.

[0311] FIG. 3 shows the overlaid DTA scans for Examples 14 (Zn.sub.2MgAl—CO.sub.3; 0% Zn stearate), 16 (Zn.sub.2MgAl—CO.sub.3; 5% Zn stearate), 17 (Zn.sub.2MgAl—CO.sub.3; 7% Zn stearate), 18 (Zn.sub.2MgAl—CO.sub.3; 10% Zn stearate) and 19 (Zn.sub.2MgAl—CO.sub.3; 15% Zn stearate) heated from ambient temperature to 800° C. Prior to DTA analysis, the samples had been exposed to 60% RH for 3 hours at 25° C. With increasing zinc stearate loading, the amount of water in the sample (outerlayer and innerlayer water) is reduced. Increased stearate decomposition in the range 400-500° C. was observed as the loading of zinc stearate in the sample increased, indicating that the modifier is successfully incorporated into the LDH.

[0312] FIG. 4 shows the moisture uptake capacity at 60% RH, 25° C. for Examples 6 (Zn.sub.2MgAl—CO.sub.3; 0% Zn stearate) and 7 (Zn.sub.2MgAl—CO.sub.3; 7% Zn stearate) measured over 180 minutes. Zinc stearate modification reduces the moisture uptake from 6% to approx. 2%.

[0313] FIG. 5 shows moisture uptake capacity at 60% RH, 25° C. measured over 180 minutes for various zinc stearate modified Zn.sub.2MgAl—CO.sub.3 samples. The samples prepared by carrying out the modifier coating step at 150° C. (Examples 17 & 18) had reduced water uptake capacity, compared to the analogous samples prepared by carrying out the modifier coating step at 110° C.

[0314] FIG. 6 shows the partition between water and 1-hexene for unmodified AMO-Zn.sub.2MgAl—CO.sub.3 (Example 14) and samples modified with stearic acid (Examples 20-22) and zinc stearate (Examples 15-18). The unmodified LDH was predominantly dispersed in the aqueous phase, while after modification the samples showed much greater propensity to partition into the 1-hexene phase. At the same loading, zinc stearate performed better than stearic acid (e.g. Example 15—3% zinc stearate compared with Example 20—3% stearic acid).

[0315] FIG. 7 shows overlaid XRD plots for unmodified Zn.sub.2MgAl—CO.sub.3 (Example 6) and Zn.sub.2MgAl—CO.sub.3 modified with 7% zinc stearate (Example 7). The XRD patterns are substantially identical, indicating that the modifier is to be found on the LDH surface, not intercalated within the LDH structure.

Preparation of PVC Composites

[0316] PVC composite materials were prepared by mixing 100 parts by weight of PVC resin, 4 parts by weight of tribasic lead sulphate, 20 parts by weight of 1,2-benzenedicarboxylic acid diisodecyl ester, 10 parts by weight of tris(2-ethylhexyl) trimellitate, 5 parts by weight of chlorinated paraffin oil, 5 parts by weight of epoxidized soybean oil, 50 parts by weight of CaCO.sub.3, 0.2 parts by weight of epoxidized PE wax, 3 parts by weight of antimony trioxide, 2 parts by weight of silicon dioxide, 1 parts by weight of acrylic processing aid, and the LDH examples as prepared (see Table 3 for LDH amounts, expressed as parts per hundred resin (phr)—e.g. 7 phr=7 parts LDH per hundred parts PVC resin by weight) in a hot melt mixer, HAAKE™ PolyLab™ OS system HAAKE Model at 180° C. for 3 minutes under a mixing speed of 60 rpm.

Characterisation of PVC Composites

Colour Stability

[0317] Colour stability of prepared PVC composites were evaluated after extrusion by spectrophotometer CM-3600A (Konica Minolta). PVC composites were compression molded into 11×11 cm.sup.2 square plaques of uniform thickness (approximately 3 mm) for measurement of whiteness index (WI) and yellowness index (YI) by spectrophotometer.

Voids

[0318] Voids of prepared PVC composites were assessed by evaluating the number of voids on a 3 mm cross-section of the PVC composites sample formed as an extruded strand, using scanning electron microscope (SEM) imaging. The samples were scanned with an accelerating voltage capacity of 1-20 k eV, at a working distance of 10 mm and a magnification at 30× at 10 kV providing a resolution of 500 μm.

[0319] The number of voids was scored according to the following criteria: [0320] 0=no voids; [0321] 1=less than 5 voids & smooth surface; [0322] 2=5-10 voids & smooth surface; [0323] 3=10-20 voids & smooth surface; [0324] 4=10-20 voids & rough surface; [0325] 5=greater than 20 voids & rough surface.

Mechanical Properties

[0326] The tensile strength and elongation at break of the PVC composites were tested according to the IEC60811-1-1 standard.

[0327] The properties of the prepared PVC composite materials are summarized in Table 3. The composites containing modified LDHs prepared according to the invention, provide higher color stability (high value of WI and low value of YI) and lower voids in comparison with the comparable composites containing unmodified LDHs.

TABLE-US-00003 TABLE 3 Amount Tensile Elongation LDH Strength at break Example LDH (phr) Wl Yl Voids (MPa) (%) 41 10 7 28.0 18.7 1 23 268 42 11 7 52.4 11.5 0 21.8 219 43 12 7 54.8 11.3 0 21.4 260 44 13 7 57.7 9.9 0 21.0 211 45 10 15 18.9 18.3 2 22.0 218 46 11 15 30.5 18.6 0 21.0 206 47 12 15 40.4 15.9 0 19.8 234 48 13 15 42.6 14.9 0 18.9 195 49 10 30 −28.3 37 5 23.1 169 50 11 30 10.1 23.2 0 19.5 184 51 12 30 16.5 23.1 0 15.2 164 52 13 30 14.9 23.4 0 14.1 143 53 6 7 54.4 11.2 1 21.4 245 54 7 7 64.3 7.5 0 20.2 219 55 8 7 59.9 9.3 0 21.6 256 56 9 7 63.9 7.4 0 20.5 213 57 6 15 23.1 15.7 1 21.5 247 58 7 15 51.8 11.6 0 19.8 194 59 8 15 52.0 11.9 0 18.8 215 60 9 15 55.6 10.0 0 17.3 164 61 6 30 −20.7 34.0 3 21.8 156 62 7 30 34.1 16.8 0 15.9 154 63 8 30 36.1 16.7 0 13.3 128 64 9 30 35.3 16.2 0 10.5 76 65 33 30 −40.1 37.0 5 — — 66 34 30 24.1 13.8 2 — — 67 35 30 29.4 12.3 2 — — 68 none — 72.4 4.2 — 25.2 278

Part II

Example 69—Preparation of LDHs (Zn.SUB.2.Al—NO.SUB.3.)

[0328] Zn(NO.sub.3).sub.2.6H.sub.2O (11.141 kg) and Al(NO.sub.3).sub.3.9H.sub.2O (7.035 kg) were dissolved in 42 L of deionized water (Solution A). A second solution was made containing Na.sub.2NO.sub.3 (11.921 kg) and NaOH (3.38 kg) dissolved in 42 L of deionized water (Solution B). Solutions A and B were added together through mixing machine at the speed of 2,900 rpm and transfer to aging tank under a stirring speed of 40 rpm at 100° C. for 4 hours. The pH was controlled at 10. After 4 hours of ageing, the resulting slurry was filtered by filter press technique, the filter cake was washed with deionized water the pH of the washings was 7, dried by vacuum oven at 110° C. for 18 hours and ground to a powder.

Example 70—Preparation of LDHs (Zn.SUB.2.Al—PO.SUB.4.)

[0329] Zn.sub.2Al—PO.sub.4 was obtained from a commercial source.

Example 71—Preparation of LDHs (Zn.SUB.2.Al—BO.SUB.3.)

[0330] Zn(NO.sub.3).sub.2.6H.sub.2O (5.942 kg) and Al(NO.sub.3).sub.3.9H.sub.2O (3.752 kg) were dissolved in 40 L of deionized water (Solution A). A second solution was made containing Boric acid (4.55 kg) and NaOH (3.29 kg) dissolved in 57 L of deionized water (Solution B). Solutions A and B were added together through mixing machine at the speed of 2,900 rpm and transfer to aging tank under a stirring speed of 40 rpm at 100° C. for 4 hours. The pH was controlled at 9. After 4 hours of ageing, the resulting slurry was filtered by filter press technique, the filter cake was washed with deionized water the pH of the washings was 7, dried by vacuum oven at 110° C. for 18 hours and ground to a powder.

Example 72—Modification of LDHs with Stearic Acid/Lauric Acid

Stearic Acid

[0331] LDHs prepared according to the methods described in Example 2 (Method 2.1) or Example 71 were heated at 150° C. for 4 hours and then mixed with stearic acid (for amounts see Table 4) via physical mixing technique via mechanical force. Then, the mixed powder is transferred to round-bottom flask to mix at a speed of 700 rpm and a temperature of 100° C. for 30 min to obtain modified LDH.

Lauric Acid

[0332] LDHs prepared according to the methods described in Example 2 (Method 2.1) or Example 71 were heated at 150° C. for 4 hours and then mixed with lauric acid (for amounts see Table 4) via physical mixing technique via mechanical force. Then, the mixed powder is transferred to round-bottom flask to mix at a speed of 700 rpm and a temperature of 70° C. for 30 min to obtain modified LDH.

Example 73—Modification of LDHs with Silanes

3-Glycidyloxypropyltrimethoxysilane

[0333] LDHs prepared according to the methods described in Example 2 (Method 2.1) were heated at 150° C. for 4 hours and then mixed with 3-Glycidyloxypropyltrimethoxysilane (for amounts see Table 4) via physical mixing technique via mechanical force. Then, the mixed powder is transferred to round-bottom flask to mix at a speed of 700 rpm and a temperature of 60° C. for 30 min to obtain modified LDH.

3-Aminopropyltrimethoxysilane

[0334] LDHs prepared according to the methods described in Example 2 (Method 2.1) were heated at 150° C. for 4 hours and then mixed with 3-Aminopropyltrimethoxysilane (for amounts see Table 4) via physical mixing technique via mechanical force. Then, the mixed powder is transferred to round-bottom flask to mix at a speed of 700 rpm and a temperature of 60° C. for 30 min to obtain modified LDH.

TABLE-US-00004 TABLE 4 Modifier AMO Loading Example LDH Method treated? Modifier (% w/w) 74 Zn.sub.2MgAl—CO.sub.3 2.1 No None — 75 Zn.sub.2MgAl—CO.sub.3 2.1 No Stearic acid 7 76 Zn.sub.2MgAl—CO.sub.3 2.1 No Lauric acid 7 77 Zn.sub.2Al—NO.sub.3 — No None — 78 Zn.sub.2Al—NO.sub.3 — No Zinc stearate 7 79 Zn.sub.2Al—PO.sub.4 — No None — 80 Zn.sub.2Al—PO.sub.4 — No Zinc stearate 7 81 Zn.sub.2Al—BO.sub.3 — No None — 82 Zn.sub.2Al—BO.sub.3 — No Zinc stearate 7 83 Mg.sub.2Al—CO.sub.3.sup.a — No None — 84 Mg.sub.2Al—CO.sub.3.sup.a — No Zinc stearate 7 85 Zn.sub.2Al—BO.sub.3 — No None — 86 Zn.sub.2Al—BO.sub.3 — No Stearic acid 7 87 Zn.sub.2Al—BO.sub.3 — No Lauric acid 7 88 Zn.sub.2MgAl—CO.sub.3 2.1 No 3-Glycidyloxypropyl- 7 trimethoxysilane 89 Zn.sub.2MgAl—CO.sub.3 2.1 No 3-Aminopropyltri- 7 methoxysilane [0335] Mg.sub.2Al—CO.sub.3.sup.a was obtained from commercial source; Examples 75, 76, 88 and 89 in Table 4 were carried out on a 10 g scale (mass of LDH); Examples 78, 80, 82, 84, 86 and 87 in Table 4 were carried out on a 1 kg scale (mass of LDH)

Characterisation of Modified LDHs

Density Measurements

[0336] Samples were heated at 110° C. for at least 3 hr to remove any excess moisture and then stored in a desiccator prior to density measurement. Sample was added to a pre-weighed 100 ml measuring cylinder, to a volume of 100 ml and then the mass of the cylinder+sample was weighed. The mass of the sample was determined by subtracting the mass of the cylinder. Bulk density (g/ml) was calculated as:

Bulk density=mass of sample (g)/100 (ml).

[0337] The measuring cylinder containing sample was then placed in an AutoTap machine (Quantachrome, Model AT-6-220-50) and subjected to tapping to reduce the volume. The tapped density (g/ml) was calculated as:

Tapped density=mass of sample (g)/volume of sample after tapping (ml).

Moisture Uptake Capacity

[0338] Pre-weighed samples were exposed at 60% (+/−5%) relative humidity, 20° C. The percentage weight change for samples after an exposure time T were calculated by:

% weight change=(wt after exposure (T mins)−wt pre-exposure)×100.

Hydrophobicity

Method A: Water/Oil Compatibility

[0339] Samples were added into a mixture of 200 ml of water/20 ml of 1-hexene. FIG. 6 shows exemplary water/oil compatibility tests. The compatibility of LDH sample in 1-hexene was evaluated by eye; good compatibility in the oil phase correlated with the sample being predominantly present in that phase; poor compatibility correlated with the sample being predominantly present in the aqueous phase.

Method B: Contact Angle Measurement

[0340] LDH samples were prepared as flat pellets with 2 cm diameter. A water droplet (10 μl) was injected by Teflon type syringe and dropped onto the LDH pellet surface. The contact angle of the water droplet on the pellet surface was measured by Contact Angle Meter DM-701 (FAMAS). Triplet measurements were made and the average of the three measurements taken.

TABLE-US-00005 TABLE 5 Bulk Tapped Surface Average density density area Oil phase Contact Example (g/ml) (g/ml) (m.sup.2/g) compatibility Angle (°) 74 — — — Poor — 75 — — — Good 135.2 76 — — — Good 138.2 77 — — — Poor 8.5 78 — — — Good 136.7 79 0.46 0.67 — Poor 0 80 0.55 0.74 — Good 135.3 81 0.22 0.33 — Poor 0 82 0.30 0.48 — Good 137.5 83 0.32 0.49 — Poor 7.7 84 0.32 0.42 — Good 135.1 85 — — — Poor 0 86 — — — Good 133.0 87 — — — Good 122.3 88 0.32 0.50 — — — 89 0.30 0.43 — — —
Table 5 illustrates that the LDH modification process increases the hydrophobicity, bulk density and/or tapped density.

Particle Size

[0341] As seen in Table 6 below, the particle size distribution D10, D50, D90 of the inventive modified LDHs (Examples 82, 86 and 87) are in the acceptable range (D10=0.5-1 micron/D50=1-3 micron/D90=2.5-6 micron) for use as an additive in polymer formulations that are processed via an extrusion technique (i.e. to achieve a good dispersion and a smooth surface), and are similar to those of the unmodified LDHs (Example 81 and 85). Therefore, the LDH modification process does not lead to the formation of aggregates.

TABLE-US-00006 TABLE 6 Particle size Particle size Particle size distribution distribution distribution Example (D10, μm) (D50, μm) (D90, μm) 81 0.68 1.69 5.77 82 0.79 2.33 5.60 85 0.68 1.69 5.77 86 0.66 1.46 3.83 87 0.71 1.89 5.58