CA2480959C - Process for the preparation of coated finely divided inorganic solids and their use - Google Patents
Process for the preparation of coated finely divided inorganic solids and their use Download PDFInfo
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- CA2480959C CA2480959C CA2480959A CA2480959A CA2480959C CA 2480959 C CA2480959 C CA 2480959C CA 2480959 A CA2480959 A CA 2480959A CA 2480959 A CA2480959 A CA 2480959A CA 2480959 C CA2480959 C CA 2480959C
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- organic
- finely divided
- coated
- inorganic solids
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- 229910003480 inorganic solid Inorganic materials 0.000 title claims abstract description 52
- 238000000034 method Methods 0.000 title claims abstract description 44
- 230000008569 process Effects 0.000 title claims abstract description 44
- 238000002360 preparation method Methods 0.000 title claims abstract description 14
- 239000002245 particle Substances 0.000 claims abstract description 26
- 239000006259 organic additive Substances 0.000 claims abstract description 21
- 239000000654 additive Substances 0.000 claims abstract description 20
- 239000007787 solid Substances 0.000 claims abstract description 18
- 239000002270 dispersing agent Substances 0.000 claims abstract description 16
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 11
- 230000000996 additive effect Effects 0.000 claims abstract description 9
- 239000000080 wetting agent Substances 0.000 claims abstract description 4
- TZCXTZWJZNENPQ-UHFFFAOYSA-L barium sulfate Chemical compound [Ba+2].[O-]S([O-])(=O)=O TZCXTZWJZNENPQ-UHFFFAOYSA-L 0.000 claims description 51
- 239000000725 suspension Substances 0.000 claims description 23
- 239000000126 substance Substances 0.000 claims description 17
- 239000000047 product Substances 0.000 claims description 15
- 239000012065 filter cake Substances 0.000 claims description 13
- -1 lithopone Substances 0.000 claims description 13
- 239000000049 pigment Substances 0.000 claims description 13
- 229920000642 polymer Polymers 0.000 claims description 13
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 13
- 239000000203 mixture Substances 0.000 claims description 10
- 239000000843 powder Substances 0.000 claims description 9
- 238000000576 coating method Methods 0.000 claims description 8
- 239000000919 ceramic Substances 0.000 claims description 7
- 239000000976 ink Substances 0.000 claims description 7
- 239000000123 paper Substances 0.000 claims description 7
- PNEYBMLMFCGWSK-UHFFFAOYSA-N Alumina Chemical compound [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 6
- ZJCCRDAZUWHFQH-UHFFFAOYSA-N Trimethylolpropane Chemical compound CCC(CO)(CO)CO ZJCCRDAZUWHFQH-UHFFFAOYSA-N 0.000 claims description 6
- 229910052751 metal Inorganic materials 0.000 claims description 6
- 239000002184 metal Substances 0.000 claims description 6
- 229920000388 Polyphosphate Chemical class 0.000 claims description 5
- 229910052783 alkali metal Inorganic materials 0.000 claims description 5
- 239000002537 cosmetic Substances 0.000 claims description 5
- 239000003973 paint Substances 0.000 claims description 5
- 229920000151 polyglycol Polymers 0.000 claims description 5
- 239000010695 polyglycol Substances 0.000 claims description 5
- 239000001205 polyphosphate Chemical class 0.000 claims description 5
- 235000011176 polyphosphates Nutrition 0.000 claims description 5
- 238000009736 wetting Methods 0.000 claims description 5
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 claims description 4
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims description 4
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 4
- 239000002202 Polyethylene glycol Substances 0.000 claims description 4
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 4
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims description 4
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 claims description 4
- 239000007900 aqueous suspension Substances 0.000 claims description 4
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 claims description 4
- 235000014113 dietary fatty acids Nutrition 0.000 claims description 4
- 150000002170 ethers Chemical class 0.000 claims description 4
- 239000000194 fatty acid Substances 0.000 claims description 4
- 229930195729 fatty acid Natural products 0.000 claims description 4
- 229920000570 polyether Chemical class 0.000 claims description 4
- 229920001223 polyethylene glycol Polymers 0.000 claims description 4
- 229920000193 polymethacrylate Chemical class 0.000 claims description 4
- 239000000344 soap Substances 0.000 claims description 4
- 229910019142 PO4 Inorganic materials 0.000 claims description 3
- 150000003863 ammonium salts Chemical class 0.000 claims description 3
- 239000002518 antifoaming agent Substances 0.000 claims description 3
- 238000004519 manufacturing process Methods 0.000 claims description 3
- 150000007524 organic acids Chemical class 0.000 claims description 3
- 235000005985 organic acids Nutrition 0.000 claims description 3
- 150000002895 organic esters Chemical class 0.000 claims description 3
- 235000021317 phosphate Nutrition 0.000 claims description 3
- 150000003013 phosphoric acid derivatives Chemical class 0.000 claims description 3
- 239000004033 plastic Substances 0.000 claims description 3
- 229920003023 plastic Polymers 0.000 claims description 3
- 150000003839 salts Chemical class 0.000 claims description 3
- DYJIIMFHSZKBDY-UHFFFAOYSA-N (3-benzoyloxy-2,2-dimethylpropyl) benzoate Chemical group C=1C=CC=CC=1C(=O)OCC(C)(C)COC(=O)C1=CC=CC=C1 DYJIIMFHSZKBDY-UHFFFAOYSA-N 0.000 claims description 2
- NIXOWILDQLNWCW-UHFFFAOYSA-M Acrylate Chemical class [O-]C(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-M 0.000 claims description 2
- 239000005995 Aluminium silicate Substances 0.000 claims description 2
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims description 2
- 229920002845 Poly(methacrylic acid) Polymers 0.000 claims description 2
- 239000005083 Zinc sulfide Substances 0.000 claims description 2
- 150000001298 alcohols Chemical class 0.000 claims description 2
- 125000001931 aliphatic group Chemical group 0.000 claims description 2
- WNROFYMDJYEPJX-UHFFFAOYSA-K aluminium hydroxide Chemical compound [OH-].[OH-].[OH-].[Al+3] WNROFYMDJYEPJX-UHFFFAOYSA-K 0.000 claims description 2
- 229910021502 aluminium hydroxide Inorganic materials 0.000 claims description 2
- 235000012211 aluminium silicate Nutrition 0.000 claims description 2
- 229910000019 calcium carbonate Inorganic materials 0.000 claims description 2
- 235000010216 calcium carbonate Nutrition 0.000 claims description 2
- 235000011132 calcium sulphate Nutrition 0.000 claims description 2
- 150000003857 carboxamides Chemical class 0.000 claims description 2
- 150000001735 carboxylic acids Chemical class 0.000 claims description 2
- 229920001577 copolymer Chemical class 0.000 claims description 2
- GDVKFRBCXAPAQJ-UHFFFAOYSA-A dialuminum;hexamagnesium;carbonate;hexadecahydroxide Chemical compound [OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Al+3].[Al+3].[O-]C([O-])=O GDVKFRBCXAPAQJ-UHFFFAOYSA-A 0.000 claims description 2
- 150000004665 fatty acids Chemical class 0.000 claims description 2
- 150000002191 fatty alcohols Chemical class 0.000 claims description 2
- SZVJSHCCFOBDDC-UHFFFAOYSA-N ferrosoferric oxide Chemical compound O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 claims description 2
- 229960001545 hydrotalcite Drugs 0.000 claims description 2
- 229910001701 hydrotalcite Inorganic materials 0.000 claims description 2
- 235000013980 iron oxide Nutrition 0.000 claims description 2
- NLYAJNPCOHFWQQ-UHFFFAOYSA-N kaolin Chemical compound O.O.O=[Al]O[Si](=O)O[Si](=O)O[Al]=O NLYAJNPCOHFWQQ-UHFFFAOYSA-N 0.000 claims description 2
- 150000002576 ketones Chemical class 0.000 claims description 2
- 239000000395 magnesium oxide Substances 0.000 claims description 2
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 claims description 2
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 claims description 2
- 150000001247 metal acetylides Chemical class 0.000 claims description 2
- 239000010445 mica Substances 0.000 claims description 2
- 229910052618 mica group Inorganic materials 0.000 claims description 2
- SLCVBVWXLSEKPL-UHFFFAOYSA-N neopentyl glycol Chemical compound OCC(C)(C)CO SLCVBVWXLSEKPL-UHFFFAOYSA-N 0.000 claims description 2
- 229910052759 nickel Inorganic materials 0.000 claims description 2
- 150000004767 nitrides Chemical class 0.000 claims description 2
- 150000002825 nitriles Chemical class 0.000 claims description 2
- 239000003960 organic solvent Substances 0.000 claims description 2
- RVTZCBVAJQQJTK-UHFFFAOYSA-N oxygen(2-);zirconium(4+) Chemical compound [O-2].[O-2].[Zr+4] RVTZCBVAJQQJTK-UHFFFAOYSA-N 0.000 claims description 2
- WXZMFSXDPGVJKK-UHFFFAOYSA-N pentaerythritol Chemical compound OCC(CO)(CO)CO WXZMFSXDPGVJKK-UHFFFAOYSA-N 0.000 claims description 2
- 229920002635 polyurethane Polymers 0.000 claims description 2
- 239000004814 polyurethane Substances 0.000 claims description 2
- 150000004756 silanes Chemical class 0.000 claims description 2
- 239000000377 silicon dioxide Substances 0.000 claims description 2
- 235000012239 silicon dioxide Nutrition 0.000 claims description 2
- 229920002545 silicone oil Polymers 0.000 claims description 2
- 150000003457 sulfones Chemical class 0.000 claims description 2
- 150000003462 sulfoxides Chemical class 0.000 claims description 2
- 239000000454 talc Substances 0.000 claims description 2
- 229910052623 talc Inorganic materials 0.000 claims description 2
- 235000012222 talc Nutrition 0.000 claims description 2
- 239000004408 titanium dioxide Substances 0.000 claims description 2
- 239000011787 zinc oxide Substances 0.000 claims description 2
- 235000014692 zinc oxide Nutrition 0.000 claims description 2
- 229910052984 zinc sulfide Inorganic materials 0.000 claims description 2
- DRDVZXDWVBGGMH-UHFFFAOYSA-N zinc;sulfide Chemical compound [S-2].[Zn+2] DRDVZXDWVBGGMH-UHFFFAOYSA-N 0.000 claims description 2
- 229910001928 zirconium oxide Inorganic materials 0.000 claims description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims 1
- 239000006185 dispersion Substances 0.000 description 7
- 238000003756 stirring Methods 0.000 description 6
- 238000009826 distribution Methods 0.000 description 5
- 238000001035 drying Methods 0.000 description 5
- 229920000139 polyethylene terephthalate Polymers 0.000 description 5
- 239000005020 polyethylene terephthalate Substances 0.000 description 5
- 239000000243 solution Substances 0.000 description 5
- 239000005068 cooling lubricant Substances 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 4
- 239000006072 paste Substances 0.000 description 4
- 239000004594 Masterbatch (MB) Substances 0.000 description 3
- 239000011248 coating agent Substances 0.000 description 3
- 230000001419 dependent effect Effects 0.000 description 3
- 238000000227 grinding Methods 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 229940127554 medical product Drugs 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- 230000009471 action Effects 0.000 description 2
- 239000000853 adhesive Substances 0.000 description 2
- 230000001070 adhesive effect Effects 0.000 description 2
- 239000003463 adsorbent Substances 0.000 description 2
- 238000005054 agglomeration Methods 0.000 description 2
- 230000002776 aggregation Effects 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 239000012876 carrier material Substances 0.000 description 2
- 239000012141 concentrate Substances 0.000 description 2
- 210000003298 dental enamel Anatomy 0.000 description 2
- 239000006260 foam Substances 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 238000003475 lamination Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000011159 matrix material Substances 0.000 description 2
- 239000002674 ointment Substances 0.000 description 2
- 238000005498 polishing Methods 0.000 description 2
- 229920005614 potassium polyacrylate Polymers 0.000 description 2
- 238000005086 pumping Methods 0.000 description 2
- 238000010008 shearing Methods 0.000 description 2
- 239000000606 toothpaste Substances 0.000 description 2
- 238000009827 uniform distribution Methods 0.000 description 2
- 241001082241 Lythrum hyssopifolia Species 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 238000004220 aggregation Methods 0.000 description 1
- 150000001340 alkali metals Chemical class 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 229910001422 barium ion Inorganic materials 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 239000004744 fabric Substances 0.000 description 1
- 238000005189 flocculation Methods 0.000 description 1
- 230000016615 flocculation Effects 0.000 description 1
- 239000013538 functional additive Substances 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- 239000011256 inorganic filler Substances 0.000 description 1
- 239000010954 inorganic particle Substances 0.000 description 1
- 239000001023 inorganic pigment Substances 0.000 description 1
- 239000010410 layer Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000012452 mother liquor Substances 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- 238000012216 screening Methods 0.000 description 1
- 239000002356 single layer Substances 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- VWDWKYIASSYTQR-UHFFFAOYSA-N sodium nitrate Chemical compound [Na+].[O-][N+]([O-])=O VWDWKYIASSYTQR-UHFFFAOYSA-N 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 239000004094 surface-active agent Substances 0.000 description 1
- 229920001059 synthetic polymer Polymers 0.000 description 1
- 229920001169 thermoplastic Polymers 0.000 description 1
- 229920001187 thermosetting polymer Polymers 0.000 description 1
- 239000004634 thermosetting polymer Substances 0.000 description 1
- 239000004416 thermosoftening plastic Substances 0.000 description 1
- 238000001238 wet grinding Methods 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2/00—Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic
- B01J2/006—Coating of the granules without description of the process or the device by which the granules are obtained
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2/00—Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic
- B01J2/30—Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic using agents to prevent the granules sticking together; Rendering particulate materials free flowing in general, e.g. making them hydrophobic
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Pigments, Carbon Blacks, Or Wood Stains (AREA)
- Medicinal Preparation (AREA)
- Cosmetics (AREA)
Abstract
A process for the preparation of coated finely divided inorganic solids is described, in which the surface of finely divided inorganic solids particles is coated with at least two different organic additives, at least one additive comprising a wetting agent, dispersing agent or deflocculating agent and the proportion of additives being not more than 15 wt.% of the coated solids.
Description
Process for the preparation of coated finely divided inorganic solids and their use The invention relates to a process for the preparation of coated finely divided inorganic solids and to their use.
inorganic solids (e.g. inorganic pigments or fillers) are incorporated inter alia as functional additives in the form of powders or dispersions into synthetic polymers, surface coatings,. paints/inks (e.g. printing inks), fibres, paper (e.g. paper for lamination) ; adhesives, ceramics (e.g. electroceramics and magnetic ceramics), enamels, adsorbents, ion exchangers, grinding and polishing agents, cooling lubricants and cooling lubricant concentrates, refractory products, hard concrete materials, medical products and cosmetics (e.g.
powders, ointments, toothpastes)- In order that the inorganic solids are able to develop their desired properties in such fields of application, very good and uniform distribution of the finely divided inorganic solids in the particular system in question is desirable.
Such uniform distribution is imperative in the case of incorporation into polymers in particular.
In order to improve the processing properties of the finely divided inorganic solids, DE 198 39 856 Al has proposed embedding them into a matrix consisting of an organic carrier material. The pulverulent intermediate formed thereby consists of individual particles having a size of < 1 m. Such a particle in tuna contains several individual inorganic solids particles, which are embedded in the organic matrix. Disadvantages of these additives are the relatively high content of organic carrier material and the relatively expensive process for the preparation of these additives.
inorganic solids (e.g. inorganic pigments or fillers) are incorporated inter alia as functional additives in the form of powders or dispersions into synthetic polymers, surface coatings,. paints/inks (e.g. printing inks), fibres, paper (e.g. paper for lamination) ; adhesives, ceramics (e.g. electroceramics and magnetic ceramics), enamels, adsorbents, ion exchangers, grinding and polishing agents, cooling lubricants and cooling lubricant concentrates, refractory products, hard concrete materials, medical products and cosmetics (e.g.
powders, ointments, toothpastes)- In order that the inorganic solids are able to develop their desired properties in such fields of application, very good and uniform distribution of the finely divided inorganic solids in the particular system in question is desirable.
Such uniform distribution is imperative in the case of incorporation into polymers in particular.
In order to improve the processing properties of the finely divided inorganic solids, DE 198 39 856 Al has proposed embedding them into a matrix consisting of an organic carrier material. The pulverulent intermediate formed thereby consists of individual particles having a size of < 1 m. Such a particle in tuna contains several individual inorganic solids particles, which are embedded in the organic matrix. Disadvantages of these additives are the relatively high content of organic carrier material and the relatively expensive process for the preparation of these additives.
In DE 100 05 685 Al, it is proposed to coat finely divided barium sulfate with an organic substance, each individual barium sulfate particle being coated with a layer of organic substance. In this process, the filter cake of barium sulfate can be processed to form a paste, with which the organic substance is mixed. The mixture is then dried. in a variant of the process, the filter cake of barium sulfate is dried and then the organic substance is added. Both processes have the disadvantage that the distribution of the organic substance on the barium sulfate particles is not uniform. in a further process variant it is proposed to suspend the filter cake of barium sulfate in water again, to add the organic substance and then to dry the mixture- Although this process results in better distribution of the organic substance on the barium sulfate particles, it has the disadvantage that a relatively large amount of water is required for preparing the suspension, which water must subsequently be removed again.
The object of the invention is to overcome the disadvantages of the prior art and provide a process with which finely divided inorganic solids can be modified with an organic substance in such a manner that they can readily be incorporated as additives into various systems (e.g. polymers, surface coatings. paints/inks, paper, ceramics, medical products or cosmetic products). In particular, the organic substance is to be distributed uniformly over the surface of the inorganic solids, and the proportion of organic substance is to be less than 15 wt.%, preferably less than 10 wt.%, of the finished additive (coated inorganic finely divided solids).
Furthermore, it is to be possible to carry out the preparation process using a smaller amount of water than in processes known hitherto in which the organic substance is added to a suspension of finely divided inorganic solids in water. If required, it is also to be possible to carry out the modification of the finely divided inorganic solids with the organic substance without using any water at all.
As such, the present invention relates to a process for the preparation of coated finely divided inorganic solids, characterised in that the surface of finely divided inorganic solids particles is coated with at least two different organic additives, at least one additive comprising a wetting agent, dispersing agent or deflocculating agent and the proportion of additives being not more than 15 wt.% of the coated solids, the finely divided inorganic solids being in the form of an aqueous suspension or in the form of a filter cake and the two different organic additives being added to the finely divided inorganic solids separately or in the form of a mixture, the resulting suspension being dried, and the coated finely divided inorganic solids having a mean particle size d50 of from 0.001 to 20 pm.
Furthermore, the present invention also relates to a use of the coated finely divided inorganic solids prepared by the process as described above as an additive in plastics, in the preparation of polymers, in surface coatings and paints/inks, in paper production, in ceramics, medical or cosmetic products.
The object is achieved by a process in which the surface of finely divided inorganic solids particles is coated with at least' two different organic additives, at least one additive comprising a wetting agent, dispersing agent or deflocculating agent and the proportion of additives being not more than 15 wt.%, preferably not more than 10 wt.%, or 5 wt.*, and particularly preferably not more than 3 wt.%, of the coated solids, the finely divided inorganic solids being in the form of an aqueous suspension or in the form of a filter cake (paste-like or 3a in dough form) and the two different organic additives being added to the finely divided inorganic solids separately or in the form of a mixture, the resulting suspension being dried and the coated finely divided inorganic solids having a mean particle size d5o of from 0.001 to 20 m.
There are preferably used as the finely divided inorganic solids, separately or in the form of a mixture, titanium dioxide, barium sulfate, lithopone, zinc sulfide, zinc oxide, calcium carbonate, calcium sulfate, iron oxide, silicon dioxide, talcum, kaolin, mica, aluminium oxide, aluminium hydroxide, metal titanates, coloured titanates (e.g. chrome nickel titanates), zirconium oxide, magnesium oxide, hydrotalcite, chalk, mixed-phase pigments, anticorrosive pigments, inorganic flameproofing pigments, black pigments (e.g. iron oxide black), inorganic special-effect pigments, or metal nitrides, carbides and borides.
The object of the invention is to overcome the disadvantages of the prior art and provide a process with which finely divided inorganic solids can be modified with an organic substance in such a manner that they can readily be incorporated as additives into various systems (e.g. polymers, surface coatings. paints/inks, paper, ceramics, medical products or cosmetic products). In particular, the organic substance is to be distributed uniformly over the surface of the inorganic solids, and the proportion of organic substance is to be less than 15 wt.%, preferably less than 10 wt.%, of the finished additive (coated inorganic finely divided solids).
Furthermore, it is to be possible to carry out the preparation process using a smaller amount of water than in processes known hitherto in which the organic substance is added to a suspension of finely divided inorganic solids in water. If required, it is also to be possible to carry out the modification of the finely divided inorganic solids with the organic substance without using any water at all.
As such, the present invention relates to a process for the preparation of coated finely divided inorganic solids, characterised in that the surface of finely divided inorganic solids particles is coated with at least two different organic additives, at least one additive comprising a wetting agent, dispersing agent or deflocculating agent and the proportion of additives being not more than 15 wt.% of the coated solids, the finely divided inorganic solids being in the form of an aqueous suspension or in the form of a filter cake and the two different organic additives being added to the finely divided inorganic solids separately or in the form of a mixture, the resulting suspension being dried, and the coated finely divided inorganic solids having a mean particle size d50 of from 0.001 to 20 pm.
Furthermore, the present invention also relates to a use of the coated finely divided inorganic solids prepared by the process as described above as an additive in plastics, in the preparation of polymers, in surface coatings and paints/inks, in paper production, in ceramics, medical or cosmetic products.
The object is achieved by a process in which the surface of finely divided inorganic solids particles is coated with at least' two different organic additives, at least one additive comprising a wetting agent, dispersing agent or deflocculating agent and the proportion of additives being not more than 15 wt.%, preferably not more than 10 wt.%, or 5 wt.*, and particularly preferably not more than 3 wt.%, of the coated solids, the finely divided inorganic solids being in the form of an aqueous suspension or in the form of a filter cake (paste-like or 3a in dough form) and the two different organic additives being added to the finely divided inorganic solids separately or in the form of a mixture, the resulting suspension being dried and the coated finely divided inorganic solids having a mean particle size d5o of from 0.001 to 20 m.
There are preferably used as the finely divided inorganic solids, separately or in the form of a mixture, titanium dioxide, barium sulfate, lithopone, zinc sulfide, zinc oxide, calcium carbonate, calcium sulfate, iron oxide, silicon dioxide, talcum, kaolin, mica, aluminium oxide, aluminium hydroxide, metal titanates, coloured titanates (e.g. chrome nickel titanates), zirconium oxide, magnesium oxide, hydrotalcite, chalk, mixed-phase pigments, anticorrosive pigments, inorganic flameproofing pigments, black pigments (e.g. iron oxide black), inorganic special-effect pigments, or metal nitrides, carbides and borides.
Wetting, dispersing or deflocculating agent is here to be understood as meaning a surface-active substance which facilitates the dispersion (= breaking up) of a pulverulent substance in a liquid medium, by lowering the S 'surface tension between two oppositely charged components by reversal of the charge of the surface. As a result, the agglomerates that are present are broken down in the dispersion process, so that re-agglomeration (= accumulation) or flocculation (= aggregation) is prevented.
As wetting, dispersing or deflocculating agents (referred to only as dispersing agents hereinbelow) there may be used both ionic and non-ionic dispersing agents. The following substances can preferably be employed; alkali metal (especially Na and K) salts or ammonium salts of organic acids (e.g. salts of poly(meth)acrylic acid), alkali metal salts of acrylate or methacrylate copolymers (having a preferred molecular weight of up to 15,000), polyphosphates (inorganic or organic polyphosphates, e.g.
poly(meth)acrylate phosphates), generally poly(meth)acrylates, polyethers, anionically modified polyethers, fatty alcohol polyglycol ethers, modified polyurethanes or anionically active aliphatic esters.
The added amount of dispersing agent is dependent on the mean particle size of the inorganic solids. The finer the inorganic solids, the greater the added amount of dispersing agent. The added amount of dispersing agent is preferably from 0.01 to 10 wt., particularly preferably from 0.01 to S wt.%, or from 0.1 to 3 wt.~, based on the finished coated product.
The second organic additive preferably comprises one or more of the following substances: carboxylic acids, soaps, metal soaps, alcohols (e.g. 1,1,1-trimethylol-propane), pentaerythritol, neopentyl glycol, polyglycols (e.g. polyethylene glycol), polyethylene glycol ethers, organic esters (e.g. neopentyl glycol dibenzoate), silanes, siloxanes, silicone oils, organic sulfones of the formula RSO2R, organic ketones (R- (C=O) -R) , organic nitriles (RCN), organic sulfoxides (R2-S02) , organic amides (R- (C=0) -IuZ?'R or R- (S=O) -ONR'R) , fatty acid esters or fatty acid amides.
The added amount of the second organic additive is also dependent on the mean particle size of the inorganic solids. The finer the inorganic solids particles, the greater the added amount of the second organic additive.
The added amount of the second organic additive is preferably from 0.01 to 10 wt.%, particularly preferably from 0.01 to 5 wt.%, or from 0.1 to 3 wt.%, based on the finished coated product.
The dispersing agent can be added to the finely divided inorganic solids separately or in admixture with the second organic additive. In the case of separate addition, the sequence of addition is in principle unimportant. For practical reasons, however, it is preferable in the case of separate addition first to add the dispersing agent and then to add the second additive.
The finely divided inorganic solids may be in the form of an aqueous suspension or in the form of a filter cake (paste-like or in dough form), It is advantageous to use a filter cake in the undried state (e.g. from current production) because the inorganic particles are then not completely agglomerated and the outlay in terms of dispersion after addition of the dispersing agent and of the second organic additive is thus minimised. If the finely divided inorganic solids are in powder form, it is e:cpedient to carry out wet grinding of the inorganic solids before preparing a suspension. The suspension or filter cake preferably has a solids content of from 15 to 85 wt.%, particularly preferably from 25 to 80 wt.;; and very particularly preferably from 50 to 80 wt.&.
Drying of the suspension provided with the additives can be carried out by means of conventional drying units.
Spray driers,- grinding driers or vacuum driers are preferably used. If required, the dried product can to subsequently be ground, for example by means of a steam-jet mill, air-jet mill or pinned disk mill.
Surprisingly, it has been found that, even with a very high solids content, suspensions or filter cakes are liquefied after addition of the dispersing agent and of the second organic additive to such an extent that optimum distribution of the additives on the particle surface is ensured and the resulting suspension can be pumped without difficulty, which reduces the outlay in terms of the process considerably. Owing to the low water content of such a "liquid" suspension, the outlay in terms of drying is also reduced.
It is also possible to mix finely divided inorganic solids in powder form with the dispersing agent and the second organic additive in a mixer and then grind the mixture, for example in a steam-jet mill, air-jet mill or pinned disk mill.
The coated finely divided inorganic so'-ids preferably have a mean particle size d5o of from 0.001 to 20 m, particularly preferably from 0.005 to 5 m, very particularly preferably from 0.01 to 2 m, or from 0.1 to 1 }lm.
An advantage of the process according to the invention is that the coated finely divided inorganic solids that are obtained have excellent flowability and can very readily be transported pneumatically. On account of these properties, they can excellently be metered for addition to polymer melts. If the coated finely divided inorganic solids are in turn to be processed further in the form of a suspension or slurry, they can be processed without a high outlay in terms of dispersion to (also non-aqueous) "liquid" dispersions having a high solids content, for example from 30 to 80 wtA, preferably from 40 to 75 wt.t. It has additionally been found that such suspensions have high stability to storage or, if solids should settle out, can very readily be re-dispersed.
There is therefore no agglomeration of the particles.
If undesirable foam formation should occur during the preparation of such a suspension (dispersion in water or an organic solvent), the foam formation can be suppressed by addition of an antifoam. The added amount of antifoam is dependent on the nature of the inorganic solids and on the nature and amount of the dispersing agent used and of the second organic additive. The added amount may be up to 3 wt.% but is generally.less than 1.5 wt.%, in each case based on the solids content of the suspension.
The coated finely divided inorganic solids prepared by the process according to the invention can be used, for example, in plastics, especially in the preparation of polymers (e.g. thermoplastic or thermosetting polymers), in surface coatings, paints/inks (e.g. printing inks), fibres, paper (e.g. paper for lamination), adhesives, ceramics (e.g. electroceramics and magnetic ceramics), enamels, adsorbents, ion exchangers, grinding and polishing agents, cooling lubricants and cooling lubricant concentrates, refractory products, hard concrete materials, medical products and cosmetics (e.g.
powders, ointments, toothpastes).
The coated finely divided inorganic solids prepared by the process according to the invention are distributed in polymers much better than finely divided inorganic solids treated according to the prior art. This manifests itself niter alia in the so-called pressure filter test.
The subject-matter of the invention is explained in greater detail by means of Examples:
Preparation for Examples A and 1: Preparation of a BaSO1 paste in known manner, barium sulfate was precipitated from aqueous solution by reaction of barium ions with sulfate ions. The precipitated BaSO4 was separated from the mother liquor and washed. The resulting paste-like filter cake consisted of 67 wt.s dry matter and 33 wt.%
water. The particle size dso of the- BaSO4 particles was 0.45 m.
Comparison Example A: Coating of the BaS04 surface with an additive according to the prior art 200 1 of demineralised water were placed in a stirrer vessel, and 120 kg of the prepared BaSO4 paste (contained 80 kg of BaSO4) were added, with stirring. 1330 ml of an aqueous 1,1,1-trimethyloipropane solution, which contained 600 g of 1,1,1-trimethylolpropane per litre of solution, were then added in portions in the course of 30 minutes under the action of the shearing forces of a dissolver (2000 rpm). 798 g (0.99 wt. %, based on the finished product) of 1,1,1-trimethy?olpropane were thus introduced. The mixture was dispersed for a further 15 minutes. The resulting suspension had a solids content of 325 g/1 (26.2 wt.%) and was spray-dried under the following conditions:
inlet temperature 535 C, outlet temperature 135 C, spraying plate 18,000 rpm, throughput 110 1/h.
The resulting pulverulent BaSO4 with a single-layer coating had a moisture content of 0.15 wt.s and a mean 3.0 particle size dso of 0.54 m.
The suspension proved to be problematical before drying in terms of its stirring and pumping properties. The reason was the high viscosity of the suspension, as was to be expected with a solids content of 26.2 wt.%.
Example 1: Coating of the BaSO4 surface with a dispersing agent and a second organic additive 28 1 of demineralised water were placed in a stirrer vessel, and 149 kg of the prepared BaSO4 paste (contained 99.8 kg of BaSO4) were added, with stirring. 400 g of a 40 % potassium polyacrylate copolymer solution in water (having a mean molar mass of about 5000) were then added in portions in the course of 30 minutes under the action of the shearing forces of a dissolver (2000 rpm). 160 g (0.16 wt.%, based on the finished product) of potassium polyacrylate copolymer were thus introduced. The mixture was dispersed for a further 15 minutes. 1642 ml of an aqueous 1,1,1-trimethylolpropane solution, which contained 600 g of 1,1,1-trimethylolpropane per litre of solution, were then added in portions, with stirring.
985 g (0.98 wt.%, based on the finished product) of 1,1,1-trimethylolpropane were thus introduced. Stirring was then carried out for a further 15 minutes. The suspension so obtained had a solids content of 960 g/l (55.9 wt.%-) and was spray-dried as described in Comparison Example A.
The coated BaSO4 powder so prepared had a moisture content of 0.15 wt.% and a mean particle size dso of 0.48 gm.
Despite the very high solids content of 55.9 wtA, the suspension had a surprisingly low viscosity before drying and accordingly exhibited very good stirring and pumping properties. The suspension could be dried without difficulty.
Comparison Example B: Processing of the coated BaSO4 from Comparison Example A in a polymer melt in a twin-screw extruder, 27 kg of BaSO4 powder from Comparison Example A were incorporated into 23 kg of polyethylene terephthalate (PET from KoSa, type:
Polyclear 1101). The temperature of the heating zone was 265 C. The concentration of BaSO4 in the PET masterbatch so prepared was 54 wtA.
Example 2: Processing of the coated BaS04 from Example 1 in a polymer melt Analogously to Comparison Example 8, 27 kg of the BaSO4 powder from Example 1 prepared by the process according to the invention were incorporated into 23 kg of polyethylene terephtha ate (PET from KoSa, type:
Polyclear 1101).
Example 3: Comparison of the polymers from Example 2 and Comparison Example B by means of the PP value In order to check the distribution of the BaSO4 solids particles in the polymer, pressure filter'tests were carried out on both the 54 % BaSO4/PET masterbatches. The PF value obtained thereby is used as a measure of the quality of masterbatches_ The lower the PF value, the better the quality of, the masterbatches in terms of the distribution of the inorganic solids particles in the polymer. The masterbatches from Example 2 and Comparison Example B were melted continuously in an extruder and fed to a 14 gm screening cloth (filter area 6.16 cm2). The temperature was 265 C in the 1st heating zone, 2700C in the 2nd heating zone and 280 C in the 3rd, 4th and Sth heating zones. The throughput was about 40 g/minute.
Measurement is complete when a pressure of 200 bar is reached or after 60 minutes at the latest. The pressure filter test values (PF value) are calculated by the following formula:
PF = (P.-Pu)xFx100[barxcrnal QI
(txKxG) wherein:
p = final pressure (bar) Po = starting pressure (bar) F = filter area (cma) t - measuring time (min) K = concentration Or pigment) G = throughput (g/min) In this manner, a PF value of 0.87 bar=cm2/g was found for the masterbatch prepared in Comparison Example S and a PF
value of only 0.19 bar=crn2/g was found for the masterbatch prepared in the Example according to the invention. This low PF value clearly shows the superiority of the coated finely divided inorganic solids prepared by the process according to the invention when incorporated into polymers.
As wetting, dispersing or deflocculating agents (referred to only as dispersing agents hereinbelow) there may be used both ionic and non-ionic dispersing agents. The following substances can preferably be employed; alkali metal (especially Na and K) salts or ammonium salts of organic acids (e.g. salts of poly(meth)acrylic acid), alkali metal salts of acrylate or methacrylate copolymers (having a preferred molecular weight of up to 15,000), polyphosphates (inorganic or organic polyphosphates, e.g.
poly(meth)acrylate phosphates), generally poly(meth)acrylates, polyethers, anionically modified polyethers, fatty alcohol polyglycol ethers, modified polyurethanes or anionically active aliphatic esters.
The added amount of dispersing agent is dependent on the mean particle size of the inorganic solids. The finer the inorganic solids, the greater the added amount of dispersing agent. The added amount of dispersing agent is preferably from 0.01 to 10 wt., particularly preferably from 0.01 to S wt.%, or from 0.1 to 3 wt.~, based on the finished coated product.
The second organic additive preferably comprises one or more of the following substances: carboxylic acids, soaps, metal soaps, alcohols (e.g. 1,1,1-trimethylol-propane), pentaerythritol, neopentyl glycol, polyglycols (e.g. polyethylene glycol), polyethylene glycol ethers, organic esters (e.g. neopentyl glycol dibenzoate), silanes, siloxanes, silicone oils, organic sulfones of the formula RSO2R, organic ketones (R- (C=O) -R) , organic nitriles (RCN), organic sulfoxides (R2-S02) , organic amides (R- (C=0) -IuZ?'R or R- (S=O) -ONR'R) , fatty acid esters or fatty acid amides.
The added amount of the second organic additive is also dependent on the mean particle size of the inorganic solids. The finer the inorganic solids particles, the greater the added amount of the second organic additive.
The added amount of the second organic additive is preferably from 0.01 to 10 wt.%, particularly preferably from 0.01 to 5 wt.%, or from 0.1 to 3 wt.%, based on the finished coated product.
The dispersing agent can be added to the finely divided inorganic solids separately or in admixture with the second organic additive. In the case of separate addition, the sequence of addition is in principle unimportant. For practical reasons, however, it is preferable in the case of separate addition first to add the dispersing agent and then to add the second additive.
The finely divided inorganic solids may be in the form of an aqueous suspension or in the form of a filter cake (paste-like or in dough form), It is advantageous to use a filter cake in the undried state (e.g. from current production) because the inorganic particles are then not completely agglomerated and the outlay in terms of dispersion after addition of the dispersing agent and of the second organic additive is thus minimised. If the finely divided inorganic solids are in powder form, it is e:cpedient to carry out wet grinding of the inorganic solids before preparing a suspension. The suspension or filter cake preferably has a solids content of from 15 to 85 wt.%, particularly preferably from 25 to 80 wt.;; and very particularly preferably from 50 to 80 wt.&.
Drying of the suspension provided with the additives can be carried out by means of conventional drying units.
Spray driers,- grinding driers or vacuum driers are preferably used. If required, the dried product can to subsequently be ground, for example by means of a steam-jet mill, air-jet mill or pinned disk mill.
Surprisingly, it has been found that, even with a very high solids content, suspensions or filter cakes are liquefied after addition of the dispersing agent and of the second organic additive to such an extent that optimum distribution of the additives on the particle surface is ensured and the resulting suspension can be pumped without difficulty, which reduces the outlay in terms of the process considerably. Owing to the low water content of such a "liquid" suspension, the outlay in terms of drying is also reduced.
It is also possible to mix finely divided inorganic solids in powder form with the dispersing agent and the second organic additive in a mixer and then grind the mixture, for example in a steam-jet mill, air-jet mill or pinned disk mill.
The coated finely divided inorganic so'-ids preferably have a mean particle size d5o of from 0.001 to 20 m, particularly preferably from 0.005 to 5 m, very particularly preferably from 0.01 to 2 m, or from 0.1 to 1 }lm.
An advantage of the process according to the invention is that the coated finely divided inorganic solids that are obtained have excellent flowability and can very readily be transported pneumatically. On account of these properties, they can excellently be metered for addition to polymer melts. If the coated finely divided inorganic solids are in turn to be processed further in the form of a suspension or slurry, they can be processed without a high outlay in terms of dispersion to (also non-aqueous) "liquid" dispersions having a high solids content, for example from 30 to 80 wtA, preferably from 40 to 75 wt.t. It has additionally been found that such suspensions have high stability to storage or, if solids should settle out, can very readily be re-dispersed.
There is therefore no agglomeration of the particles.
If undesirable foam formation should occur during the preparation of such a suspension (dispersion in water or an organic solvent), the foam formation can be suppressed by addition of an antifoam. The added amount of antifoam is dependent on the nature of the inorganic solids and on the nature and amount of the dispersing agent used and of the second organic additive. The added amount may be up to 3 wt.% but is generally.less than 1.5 wt.%, in each case based on the solids content of the suspension.
The coated finely divided inorganic solids prepared by the process according to the invention can be used, for example, in plastics, especially in the preparation of polymers (e.g. thermoplastic or thermosetting polymers), in surface coatings, paints/inks (e.g. printing inks), fibres, paper (e.g. paper for lamination), adhesives, ceramics (e.g. electroceramics and magnetic ceramics), enamels, adsorbents, ion exchangers, grinding and polishing agents, cooling lubricants and cooling lubricant concentrates, refractory products, hard concrete materials, medical products and cosmetics (e.g.
powders, ointments, toothpastes).
The coated finely divided inorganic solids prepared by the process according to the invention are distributed in polymers much better than finely divided inorganic solids treated according to the prior art. This manifests itself niter alia in the so-called pressure filter test.
The subject-matter of the invention is explained in greater detail by means of Examples:
Preparation for Examples A and 1: Preparation of a BaSO1 paste in known manner, barium sulfate was precipitated from aqueous solution by reaction of barium ions with sulfate ions. The precipitated BaSO4 was separated from the mother liquor and washed. The resulting paste-like filter cake consisted of 67 wt.s dry matter and 33 wt.%
water. The particle size dso of the- BaSO4 particles was 0.45 m.
Comparison Example A: Coating of the BaS04 surface with an additive according to the prior art 200 1 of demineralised water were placed in a stirrer vessel, and 120 kg of the prepared BaSO4 paste (contained 80 kg of BaSO4) were added, with stirring. 1330 ml of an aqueous 1,1,1-trimethyloipropane solution, which contained 600 g of 1,1,1-trimethylolpropane per litre of solution, were then added in portions in the course of 30 minutes under the action of the shearing forces of a dissolver (2000 rpm). 798 g (0.99 wt. %, based on the finished product) of 1,1,1-trimethy?olpropane were thus introduced. The mixture was dispersed for a further 15 minutes. The resulting suspension had a solids content of 325 g/1 (26.2 wt.%) and was spray-dried under the following conditions:
inlet temperature 535 C, outlet temperature 135 C, spraying plate 18,000 rpm, throughput 110 1/h.
The resulting pulverulent BaSO4 with a single-layer coating had a moisture content of 0.15 wt.s and a mean 3.0 particle size dso of 0.54 m.
The suspension proved to be problematical before drying in terms of its stirring and pumping properties. The reason was the high viscosity of the suspension, as was to be expected with a solids content of 26.2 wt.%.
Example 1: Coating of the BaSO4 surface with a dispersing agent and a second organic additive 28 1 of demineralised water were placed in a stirrer vessel, and 149 kg of the prepared BaSO4 paste (contained 99.8 kg of BaSO4) were added, with stirring. 400 g of a 40 % potassium polyacrylate copolymer solution in water (having a mean molar mass of about 5000) were then added in portions in the course of 30 minutes under the action of the shearing forces of a dissolver (2000 rpm). 160 g (0.16 wt.%, based on the finished product) of potassium polyacrylate copolymer were thus introduced. The mixture was dispersed for a further 15 minutes. 1642 ml of an aqueous 1,1,1-trimethylolpropane solution, which contained 600 g of 1,1,1-trimethylolpropane per litre of solution, were then added in portions, with stirring.
985 g (0.98 wt.%, based on the finished product) of 1,1,1-trimethylolpropane were thus introduced. Stirring was then carried out for a further 15 minutes. The suspension so obtained had a solids content of 960 g/l (55.9 wt.%-) and was spray-dried as described in Comparison Example A.
The coated BaSO4 powder so prepared had a moisture content of 0.15 wt.% and a mean particle size dso of 0.48 gm.
Despite the very high solids content of 55.9 wtA, the suspension had a surprisingly low viscosity before drying and accordingly exhibited very good stirring and pumping properties. The suspension could be dried without difficulty.
Comparison Example B: Processing of the coated BaSO4 from Comparison Example A in a polymer melt in a twin-screw extruder, 27 kg of BaSO4 powder from Comparison Example A were incorporated into 23 kg of polyethylene terephthalate (PET from KoSa, type:
Polyclear 1101). The temperature of the heating zone was 265 C. The concentration of BaSO4 in the PET masterbatch so prepared was 54 wtA.
Example 2: Processing of the coated BaS04 from Example 1 in a polymer melt Analogously to Comparison Example 8, 27 kg of the BaSO4 powder from Example 1 prepared by the process according to the invention were incorporated into 23 kg of polyethylene terephtha ate (PET from KoSa, type:
Polyclear 1101).
Example 3: Comparison of the polymers from Example 2 and Comparison Example B by means of the PP value In order to check the distribution of the BaSO4 solids particles in the polymer, pressure filter'tests were carried out on both the 54 % BaSO4/PET masterbatches. The PF value obtained thereby is used as a measure of the quality of masterbatches_ The lower the PF value, the better the quality of, the masterbatches in terms of the distribution of the inorganic solids particles in the polymer. The masterbatches from Example 2 and Comparison Example B were melted continuously in an extruder and fed to a 14 gm screening cloth (filter area 6.16 cm2). The temperature was 265 C in the 1st heating zone, 2700C in the 2nd heating zone and 280 C in the 3rd, 4th and Sth heating zones. The throughput was about 40 g/minute.
Measurement is complete when a pressure of 200 bar is reached or after 60 minutes at the latest. The pressure filter test values (PF value) are calculated by the following formula:
PF = (P.-Pu)xFx100[barxcrnal QI
(txKxG) wherein:
p = final pressure (bar) Po = starting pressure (bar) F = filter area (cma) t - measuring time (min) K = concentration Or pigment) G = throughput (g/min) In this manner, a PF value of 0.87 bar=cm2/g was found for the masterbatch prepared in Comparison Example S and a PF
value of only 0.19 bar=crn2/g was found for the masterbatch prepared in the Example according to the invention. This low PF value clearly shows the superiority of the coated finely divided inorganic solids prepared by the process according to the invention when incorporated into polymers.
Claims (23)
1. Process for the preparation of coated finely divided inorganic solids, characterised in that the surface of finely divided inorganic solids particles is coated with at least two different organic additives, at least one additive comprising a wetting agent, dispersing agent or deflocculating agent and the proportion of additives being not more than 15 wt.% of the coated solids, the finely divided inorganic solids being in the form of an aqueous suspension or in the form of a filter cake and the two different organic additives being added to the finely divided inorganic solids separately or in the form of a mixture, the resulting suspension being dried, and the coated finely divided inorganic solids having a mean particle size d50 of from 0.001 to 20 µm.
2. Process according to claim 1, wherein the filter cake is paste-like or in dough form.
3. Process according to claim 1, characterised in that the finely divided inorganic solids are in the form of a powder instead of in the form of a suspension or filter cake and are mixed with the two different organic additives in a mixer and the mixture is then ground.
4. Process according to any one of claims 1 to 3, characterised in that the proportion of additives is not more than 10 wt.% of the coated solids.
5. Process according to any one of claims 1 to 4, characterised in that the proportion of additives is not more than 5 wt.% of the coated solids.
6. Process according to any one of claims 1 to 5, characterised in that there are used as the finely divided inorganic solids, separately or in the form of a mixture, titanium dioxide, barium sulfate, lithopone, zinc sulfide, zinc oxide, calcium carbonate, calcium sulfate, iron oxide, silicon dioxide, talcum, kaolin, mica, aluminium oxide, aluminium hydroxide, metal titanates, coloured titanates, zirconium oxide, magnesium oxide, hydrotalcite, chalk, mixed-phase pigments, anticorrosive pigments, inorganic flameproofing pigments, black pigments, inorganic special-effect pigments, or metal nitrides, carbides and borides.
7. Process according to claim 6, wherein the coloured titanates are chrome nickel titanates.
8. Process according to claim 6, wherein the black pigments are iron oxide black pigments.
9. Process according to any one of claims 1 to 8, characterised in that the wetting, dispersing or deflocculating agent comprises one or more of the following substances: alkali metal salts or ammonium salts of organic acids, alkali metal salts of acrylate or methacrylate copolymers, polyphosphates, poly(meth)acrylates, polyethers, anionically modified polyethers, fatty alcohol polyglycol ethers, modified polyurethanes or anionically active aliphatic esters.
10. Process according to claim 9, wherein the alkali metal salts or ammonium salts of organic acids are salts of poly(meth)acrylic acid.
11. Process according to claim 9 or 10, wherein the polyphosphates are inorganic or organic polyphosphates.
12. Process according to claim 11, wherein the inorganic or organic phosphates are poly(meth)acrylate phosphates.
13. Process according to any one of claims 1 to 12, characterised in that the added amount of wetting, dispersing or deflocculating agent is from 0.001 to 10 wt.%, based or the finished coated product.
14. Process according to claim 13, characterised in that the added amount of wetting, dispersing or deflocculating agent is from 0.001 to 5 wt. %, based on the finished coated product.
15. Process according to any one of claims 1 to 14, characterised in that the second organic additive comprises one or more of the following substances:
carboxylic acids, soaps, metal soaps, alcohols, pentaerythritol, neopentyl glycol, polyglycols, polyethylene glycol ethers, organic esters, silanes, siloxanes, silicone oils, organic sulfones, organic ketones, organic nitriles, organic sulfoxides, organic amides, fatty acid esters or fatty acid amides.
carboxylic acids, soaps, metal soaps, alcohols, pentaerythritol, neopentyl glycol, polyglycols, polyethylene glycol ethers, organic esters, silanes, siloxanes, silicone oils, organic sulfones, organic ketones, organic nitriles, organic sulfoxides, organic amides, fatty acid esters or fatty acid amides.
16. Process according to claim 15, wherein the alcohol is 1,1,1-trimethylol-propane.
17. Process according to claim 15 or 16, wherein the polyglycol is polyethylene glycol.
18. Process according to any one of claims 15 to 17, wherein the organic ester is neopentyl glycol dibenzoate.
19. Process according to any one of claims 1 to 18, characterised in that the added amount of the second organic additive is from 0.01 to 10 wt.%, based on the finished coated product.
20. Process according to claim 19, characterised in that the added amount of the second organic additive is from 0.01 to 5 wt.%, based on the finished coated product.
21. Process according to any one of claims 1 to 20, characterised in that the coated finely divided inorganic solids have a mean particle size d50 of from 0.005 to µm.
22. Use of the coated finely divided inorganic solids prepared by the process according to any one of claims 1 to 21 as an additive in plastics, in the preparation of polymers, in surface coatings and paints/inks, in paper production, in ceramics, medical or cosmetic products.
23. Use according to claim 22, characterised in that the coated finely divided inorganic solids are dispersed in water or as organic solvent, an antifoam being added in an added amount of up to 3 wt.%, based on the solids content of the suspension.
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