Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B82—NANOTECHNOLOGY
  • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
  • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK  ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
  • C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
  • C09C1/0081—Composite particulate pigments or fillers, i.e. containing at least two solid phases, except those consisting of coated particles of one compound
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK  ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
  • C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
  • C09C1/0081—Composite particulate pigments or fillers, i.e. containing at least two solid phases, except those consisting of coated particles of one compound
  • C09C1/0084—Composite particulate pigments or fillers, i.e. containing at least two solid phases, except those consisting of coated particles of one compound containing titanium dioxide
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK  ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
  • C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
  • C09C1/40—Compounds of aluminium
  • C09C1/42—Clays
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK  ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
  • C09C3/00—Treatment in general of inorganic materials, other than fibrous fillers, to enhance their pigmenting or filling properties
  • C09C3/06—Treatment with inorganic compounds
  • C09C3/063—Coating
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2002/00—Crystal-structural characteristics
  • C01P2002/80—Crystal-structural characteristics defined by measured data other than those specified in group C01P2002/70
  • C01P2002/84—Crystal-structural characteristics defined by measured data other than those specified in group C01P2002/70 by UV- or VIS- data
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/01—Particle morphology depicted by an image
  • C01P2004/03—Particle morphology depicted by an image obtained by SEM
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/50—Agglomerated particles
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/51—Particles with a specific particle size distribution
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  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/60—Particles characterised by their size
  • C01P2004/61—Micrometer sized, i.e. from 1-100 micrometer
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/60—Particles characterised by their size
  • C01P2004/62—Submicrometer sized, i.e. from 0.1-1 micrometer
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/60—Particles characterised by their size
  • C01P2004/64—Nanometer sized, i.e. from 1-100 nanometer
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/80—Particles consisting of a mixture of two or more inorganic phases
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2006/00—Physical properties of inorganic compounds
  • C01P2006/12—Surface area
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  • C01P2006/60—Optical properties, e.g. expressed in CIELAB-values
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  • C01P2006/80—Compositional purity

Definitions

• This invention relates to structural aggregate pigm products comprising a quantitatively predominant particul matter and complex functional microgels which are essentia non-reactive therewith.
• this invention relates to novel structu aggregate pigment products which are manufactured from aque dispersions of particulate matter treated with in-situ fo complex functional microgels.
• this invention relates to structural gregate pigment products which comprise particulate matter fl culated and cemented with complex (multicomponent) functiono microgels.
• colloids are the lowest-rank systems known in nature equi ped with “memory.” As such, they "remember” their history chronological detail and react accordingly in terms of the resultant properties and functional behavior. As a consequenc any intentional or accidental deviation from an establish synthesis procedure or reaction conditions will inescapab cause certain differences, mostly quantitative but sometim profoundly qualitative, in the constitution and/or function properties of the resultant colloidal systems.
• silica or silico-alu inate gels in aqueous media for the purpose of surface coating of mineral particles has been utilized commercially for many years.
• titanium dioxide pigments on the market are coated with a more or less dense layer of silica, or silico- aluminate, gels deposited in situ by a controlled interaction between relatively highly concentrated solutions of sodium silicate and appropriate gel-setting agents such as sulfuric or hydrochloric acids, ammonium sulfate, alum or sodium aluminate, in aqueous dispersions of the pigment.
• the surface coa ⁇ tings mentioned represent continuous gels which are fundamental ⁇ ly different from the instantaneously in-situ formed microparti- culate gels (microgels) used in practicing the present invention developed by the Applicant and disclosed in co-pending patent application (Serial No. 07/350,4 . 68 ; Filed May 11, 1989 ).
• microgels microparti- culate gels
• the slow formation kinetics and continuous structure of gels used in surface coating of titanium dioxide pigments in accordance with the present art excessive uncon ⁇ trollable cementation of individual particles into very abrasive oversized aggregates can not be avoided.
• U.S. Patent 3,726,000 to Wildt relating to the use of in-situ formed continuous alumino-silicate gels as intrinsic cements toward the preparation of composite pigments, may be considered as typical of the general prior art in this area of technology dating back for over half a century.
• Many other intrinsic cementing media have also been used for the same purpose, e.g., sodium silicate and aluminum chloride in U.S. Patent No. 2,176,876 to Alessandroni, aliphatic acid in U.S. Patent No. 3,453,131 to Fadner, ethylenediamine and citric acid in U.S. Patent No. 4,075,030 to Bundy, urea-formaldehyde in U.S. Patent No. 4,346,178 to Economou, or silicon tetrachlor- ide in WO 87/00544 to Jones.
• Wildt*s composite pigments were intended for latex-paint applications in which the resultant excessive aggregate hardness (abrasiveness) , restricting or even prohibiting the e of these pigments in paper filling and coating, does not constitute a real disadvantage.
• Principal gel compositions and experimental procedures for in-situ formation of continuous gel cements dis ⁇ closed in the patent to Wildt are identical to those utilized commercially for many decades toward surface coating of titanium dioxide pigments mentioned previously. It should be pointed out in this context that while a certain controlled level of residu ⁇ al particle cementation (permanent aggregation) is quite essen ⁇ tial to synthesis of composite pigments, any permanent aggrega ⁇ tion is totally undesirable when continuous gels are used for surface coating of titanium dioxide pigments.
• Continuous gels with particle-immobilizing and cementing functions were synthesized according to Wildt by an interaction between sodium silicate and aluminum sulfate in aqueous disper ⁇ sions of particulate raw materials used for preparation of com ⁇ posite pigments, using relatively high concentrations of gel forming reagents.
• the particulate raw materials mentioned con ⁇ sisted of titanium dioxide as the principal optically-active in ⁇ gredient, as well as coarse-particle-size, very abrasive, cal ⁇ cined clays (Engelhard f s Satintone No.l or No.4) and/or coarse delaminated clay as extenders.
• the procedure described involved several independent critical processing steps, such as heating of the reaction medium (to speed up the formation of continuous gel) , alkaline pH adjustments, and long digestion periods (last ⁇ ing from 30 to 60 minutes) followed by additional acidic pH ad ⁇ justments.
• heating of the reaction medium to speed up the formation of continuous gel
• alkaline pH adjustments to speed up the formation of continuous gel
• long digestion periods last ⁇ ing from 30 to 60 minutes
• additional acidic pH ad ⁇ justments followed by additional acidic pH ad ⁇ justments.
• Hoffmann so-called silicomagnesium-aluminate-hydrate gel is factually mechanical blend of separately prepared silico-aluminate gel a a magnesium hydroxide gel, hence, fundamentally different fr true complex gels used in practicing the present invention.
• Hoffmann's antacid gel was prepared by mixi concentrated solutions of sodium silicate and an aluminum sa 1 under alkaline conditions for extended periods of time, e.g., minutes, to form a solidified silico-aluminate cogel.
• Th cogel was subsequently crushed and homogenized into a flowab pulp, into which a concentrated solution of magnesium sulfa was introduced gradually over a period of time lasting 3 hour As a consequence, the in-situ precipitated magnesium hydroxi hydrate became mechanically, though intimately, dispersed with the previously fluidized pulp of the continuous silico-alumina cogel.
• Inorganic anion-exchangers and a process for their synthes are disclosed by Duwell in U.S. Patent No. 3,002,932.
• the abo ion exchangers are prepared by "coprecipitating mix hydrated oxides of a pair of homolomorphic metals chosen fr the group consisting of aluminum, silicon, titanium, zinc, a zirconium, the lower-valent member of said pair being present major amount, in an aqueous medium at a pH in the range of abo pH 5 to 7, drying the aqueous mixture at a temperature bel 150°C, and washing the dried mixture with water to remo soluble impurities therefrom.”
• the above technology, as quote is based again on physical mixtures of separately formed ge rather than true complex microgels made up of intrinsical chemically bound complex macromolecules.
• Tu In addition to using silica-alumina cogels as crackin catalyst precursors, Tu also employed certain specific brand anionic polyacrylamide (transient adjuvant) to modify t mechanical structure of catalyst matrix. Accordingly, after subsequent burnout of the organic substance occluded in t latter matrix, Tu was able to obtain a more favorable pore-si distribution. As far as purely chemical functions of t anionic polyacrylamide with regard to catalyst formation a concerned, Tu cautiously offers the following hypothes proposed also in other similar patents: "it is believed that t anionic form chemically react with the silica-alumina g framework, rather than being physically dispersed in the ge and thus contributes to the desired pore structure formation.
• Kaliski in U.S. Patent No. 3,484,271 describes the formati of functional (release) coatings on moving paper webs by an i l o situ interaction between consecutively applied separa solutions of organic anionic and cationic compounds with a least two functional groups in each molecule.
• These releas coatings are made in the form of continuous, totally impervious gel films devoid of any particulate occlusions. As a matter o fact, a particulate matter embedded in such films would destro more or less completely these films' useful release properties.
• U.S. Patent No. 2,974,108 to Alexander discloses synthesis o stable aluraino-silicate aquasols (hydrosols) with ion-exchang capacities equivalent to those of better zeolites, and also ver good antisoiling properties.
• These aquasols are prepared wit the aid of rather intricate thermal regimes and time-consumin procedures, using silicic acid (rather than straight alkali metal silicate, or quaternary ammonium silicate, used in prac ticing the present invention) and sodium aluminate as the prin cipal reagents.
• the end product contain preferably from 5% to 20% of substantially spheroidal porou particles suspended in an aqueous medium with pH ranging betwee 5 and 10, the preferred diameter of aquasol particles rangin from 10 to 50 milimicron (nanometer) and particle porosity fro 10% to 70%.
• the aquasols hydrosols according to Alexander are end products in themselves and chemi cally non reactive, whereas the hydrosols used in practicing th present invention are short-lived intermediate products charac terized by a high level of chemical reactivity.
• the single-component and multi-component structural agg gate pigment products of the present invention comprise:
• ratio of said reagents employed in (i) to said reagents employed in (ii) ranges from 1:10 to 10:1, by weight, an the ratio of total reagents in (2) to gel-setting agents in (1 ranges from 1:10 to 10:1.
• novel structural aggregate pigment products for paper fillin paper coating are manufactured synthesizing in situ complex functional microgels in aqueo dispersions of quantitatively predominant particulate matte also containing water-soluble functional adjuvants.
• the princ pal particulate raw materials for the manufacture of structur aggregate pigments include a variety of mineral and organ pigment products of the present art, as well as ultrafine whi or colorless mineral and/or organic particles with dimensio ranging from 0.01 ⁇ to 0.1 ⁇ m e.s.d.
• Structural aggregate pigments may be made from a sing principal particulate species, e.g., kaolin clay. Such pigmen shall be called further on “simple aggregate pigments," differentiation to “composite pigments” which shall relate structural aggregate pigments made from two or more differe principal particulate mineral species.
• the primary purpose of the in-situ formed complex microgels is to induce instantaneous (ultrarapid) , indiscriminate and complete flocculation of all disperse phases present in the reaction medium. Flocculation phenomena play fundamental and indispensable roles in the manufacture of all structural aggregate pigments.
• the flocculation processes of the present art are slow, selective (rather than indiscriminate) , and incomplete.
• Particulate raw materials for the manufacture of such exotic composite pigments encompass, for example, various naturally oc ⁇ curring and synthetic minerals with particle sizes ranging from 0.01 urn to 10 ⁇ nx e.s.d., non-film-forming (high glass-transition temperature) organic emulsion polymers with particle diameters ranging from 0.03 p ⁇ & to 1 Jm, latex adhesives with particle diameters ranging from 0.07 ⁇ m to 0.3 ⁇ m, and color pigments with particle diameters even smaller than 0.01 jam.
• non-film-forming (high glass-transition temperature) organic emulsion polymers with particle diameters ranging from 0.03 p ⁇ & to 1 Jm
• latex adhesives with particle diameters ranging from 0.07 ⁇ m to 0.3 ⁇ m
• color pigments with particle diameters even smaller than 0.01 jam The enormous quantitative and qualitative heterogeneity of above furnishes are realized best when considering that the linear dimensions of individual particles span over 3 orders of magnitude, hence, the corresponding volu.
• the relative densities of particulate matter may vary from about 1 g/cm 3 for certain IS plastics to 4.2 g/cm 3 for titanium dioxide pigments, while th surface-chemical properties of particulates may range from ver hydrophilic to extremely hydrophobic.
• the secondary purpose of the complex microgels disclose herein is to provide an arbitrary level of intrinsic cementatio to aggregated pigment particles upon subsequent drying, or othe finishing operations.
• the desired level of cementation can b attained by varying composition and/or dosage of the functiona complex microgels, such as to provide structural aggregate pig ment products with sufficient mechanical integrity to withstan the customary shearing (loading) and/or comminution regimes t which they may be exposed in practical handling and end-us operations.
• microgels are obviously larger than those of silico-aluminate, silico-zincate, or silico-aluminate- zincate hydrosols from which they were derived through cross- linking (polycondensation) with bivalent or multivalent inorgan ⁇ ic salts and/or organic cationically-active chemical compounds with two o_r more reactive groups in each molecule, they could not be detected visually under 50,000 X magnification in elec- tronphotomicrographs of dried and pulveri ⁇ ..d composite pigments prepared with the aid of these microgels.
• Spheroidal hydrosol particles with diameters ranging from 10 nm to 50 nm described in U.S. Patent No. 2,974,108 to Alexander, on the other hand, can be
• the tertiary purpose of the complex microgels disclosed herein is to impart directly, by virtue of their inherent physical and surface-chemical properties, certain specific material and functional properties to the aggregated and cemented products, important from the standpoint of these prod ⁇ ucts' end-use applications.
• the above effects can be realized through purposeful modification of the chemical composition, and/or physical properties, of the complex functional microgels.
• surface-chemical modification providing enhanced compatibility with organic media may be attained by intrinsic incorporation of suitable organic polyelectrolytes, and/or other specialized agents, into macromolecules which make up the complex microgels of the present invention.
• Composite pigments synthesized with the aid of such microgels with built-in organic groups (functionalities) are especially well suited as fillers for plastics, since they can be easily and uniformly dispersed in oleophilic media.
• Anionic polyelectrolytes with microgel-modifying functions encompassing, among other things, sodium salts of polyacrylic acid or carboxymethyl cellulose, may be introduced into the system through the anionic stream, e.g., along with sodium silicate or sodium aluminate, or added directly to the particu ⁇ late dispersion.
• Cationic modifying agents encompassing, among other things, selected bivalent or multivalent inorganic salts, as well as organic cationically-active compounds with at least ⁇ i two reactive groups in each molecule, may be introduced into th system along with the solution of the principal bivalent o multivalent inorganic salt(s) used for microgel formation.
• alkali-metal silicates and quaternar ammonium silicates preferably sodium silicate
• water soluble, essentially colorless, bivalent and multi-valen inorganic salts preferably calcium chloride and calcium nitrat but equally well other similar salts of calcium, magnesium barium, aluminum, zinc and zirconium, as well as cat onically active organic compounds with at least two reactive groups i each molecule, capable of performing the same gel-settin functions as bivalent or multivale*- inorganic salts.
• anionic and cationic organic ditives used in the proces must be compatible with their respective anionic and cationi 14 reaction streams, as indicated by absence of phase separati clouding, or premature gelling.
• the above complex microgels a made up of macromolecules of hybrid polymer-p ⁇ lycondensate ty the polymerization reaction being at the foundations of hydros formation while polycondensation takes place during crossli ing of the reactive hydrosols by cationic gel-setting agen Inorganic/organic hetero-macromolecules of the same polym polycondensate type are formed when organic chemical compou with at least two reactive groups in each molecule are built i trinsically into the microgel structure.
• the ratio of sodium silicate to sodium alum.nate, sodium silicate to sodium zincate, or sodium silicate to the combined mass of sodium aluminate and sodium zincate in forming the subcolloidal reactive hydrosols may range from 10:1 to 1:10, by weight, the preferred ratio for most applications pertaining to the synthesis of structural aggregate pigments being 1:1.
• concentration * of sodium silicate in aqueous slurries of particulate matter should vary optimal from 0.1% to 2%, by weight, the same pertaining also to sodi aluminate, sodium zincate, or combination thereof.
• the ratio of organic, cationically active, crosslinki 3 ⁇ agents to hydrosol mass must be determined empirically for eac individual compound and specific application. The reason fo this is that the chemical properties of above organic material are vastly more differentiated from the standpoint of thei effect upon end-use properties of structural aggregate pigmen products than are those of corresponding inorganic crosslinkin agents. As a general rule, the relative proportion of the abov organic crosslinking agents should range from 0.1% to 5% of th mass of particulate matter.
• th anionic and cationic streams in the process for synthesizin structural aggregate pigments of the present invention may b reversed by blending solutions of bivalent and multivalen inorganic salts and/or organic, cationically active, chemica compounds with at least two reactive groups in each molecul with aqueous dispersions of particulate matter in step (a) preparing subcolloidal reactive sodium-silico-alu inate (silico zincate or ⁇ ilico-aluminate-zincaie) hydrosols independently i step (b) ; and blending in step (c) systems resulting fro steps (a) and (b) to form in situ complex functional microgel to flocculate the particulate matter instantaneously, indiscrim inately and completely to synthesize structural aggregate pig ment products.
• step (c) The pH of the flocculated structural aggregate pigment pro ucts from step (c) above ranges usually from 10 to 12.
• p determined amounts of sulfuric acid, or other inorganic or o ganic acidifying agents may be added to the dispersion of pa ticulate matter in step (a) .
• the amount of agents necessary lower pH to the desired level must be assessed independently, titrating a sample of the alkaline medium from step (c) wi solutions of the acidifying agents to be employed.
• the resultant pH of the flocculated medium in st (c) could be lowered to 3.5
• the colloidal stability of mo dispersions of particulate matter used for synthesis of stru tural aggregate pigments of the present invention will be im paired intolerably below pH of 5, or even 5.5.
• the complex functional microgels used in practicing t present invention may also be prepared independently, in pla water, and then blended with a dispersion of particulate matt to flocculate the latter indiscriminately and completely, b not instantaneously, to form a structural aggregate pigme product. It should be emphasized, however, that the proce version in which subcolloidal reactive hydrosols are synthesiz first in aqueous dispersions of particulate matter, follow by addition of cationic crosslinking agents, is preferred f the synthesis of structural aggregate pigments according to t present invention.
• the latter pigments are typified by No. 1 V.F. (Number O Very Fine) , high-glossing, hydrous coating clays which conta 95% - 100%, by weight, of particles smaller than 2 m e.s. (equivalent spherical diameter), less than 10%, by weight, particles smaller than 0.1 urn e.s.d., and have an avera particle size ranging from 0.2 i to 0.4 ym e.s.d.
• above clay products may be described as being manufactured f inherently very fine particle size crudes by blunging the lat in water, removing particulate impurities larger than 44 e.s.d.
• the latter fraction is s sequently beneficiated by physical methods such as high-gradie magnetic separation, colloidal-chemical methods such as flot tion and selective flocculation, and chemical methods such oxidation and reduction bleaching important also from the stan point of chemical stabilization of the end product.
• very fine particle size clays are used mai ly as diluents for regular coating clays derived from substa tially more valuable, coarser, more crystalline "white" cl crudes.
• the light-scattering coefficients of clay pigments ma 100% from the latter crudes are about two to three times high than those of very fine particle size, high-glossing clays.
• white crudes, particularly those having good rhe logical properties, are progressively more scarce.
• admixing of up to 50% of optically inferior very fi particle size clays into commercial coating clay products h become a virtual necessity throughout the clay industry.
• the in-situ formed complex functional microgels mentio above make possible to synthesize new types of structural agg gate pigment products uniquely suited toward paper coating filling applications, filling of plastics, and many other pra tical uses.
• the optical performance of such structural aggrega pigments synthesized from a variety of commercial pigment pro ucts and other mineral and organic particulates, as well as so uble components, is substantially better than that of the orig nal raw materials used in non-aggregated form.
• Many unique pe formance properties, as well as structural and surface-chemic features, can be imparted to these aggregate pigments almost will by purposeful a-priori design.
• ultrahigh bulking which brin about spectacularly rapid setting of coating films on paper su face.
• su as is normally indispensable to setting of wet films containi standard coating pigments or conventional bulking pigments.
• coating formations containing ultrahigh bulki pigments of the present invention become immobilized (se rapidly without dewatering, yielding smoother and more unifo coatings with higher gloss, brightness and opacity, as well better glueability and printability, than analogous coating fo mations containing pigments of the present art.
• Surface-chemical modification of structural aggregate pi ments of the present invention can be affected by building i organic groups into macromolecules making up the microgels an through incorporation of organic particulates into the aggregat pigment structure, thus imparting controlled levels of affinit toward organic (non-polar) media in addition to the inheren affinity of (polar) mineral pigments toward water.
• the structural aggregate pigments acquire intrinsi dual-matrix surface characteristics of hydrophilic/organophili type well suited, for example, toward uniform and efficien dissipation both of water and ink solvents in offset printing.
• anionic and cationic organic polymer in daily use by the paper and pigment industries identified onl by trade names, molecular weights, and ionic type, which can b employed toward microgel formation if they are compatible wit the respective ionic streams.
• anionic polymers suc as sodium salts of polyacrylic acid or carboxymethyl-cellulos are compatible with the anionic process stream if they are no coagulated, or salted out, by strongly alkaline solutions o sodium silicate, aluminate or zincate.
• cationic polymers e.g., polyacrylamides
• polyacrylamides are compatible with the cationi stream if they are not coagulated, or salted out, by solution of bivalent and mutivalent inorganic salts.
• a vast number o organic monomolecular anionic and cationic chemical compound with two or more reactive groups in each molecule can be used i addition to, or instead of, organic ionic polymers mentione above.
• anionic compounds are sodium salts o N-(l,2-dicarboxyethyl)-N-alkyl sulpho-succinamate (Aerosol 22) or ethylenediamine tetraac ⁇ tic acid, while methyl-dodecylbenzyl 53 trimethyl ammonium chloride-methyldodecylxylene bis(tri eth ammonium chloride (Hyamin 2389) is representative of orga cationic compounds with two reactive groups in each molecul
• addition levels of the latter vary from 0.1% to 5%, on the total mass of mineral particulat Lower addition levels of these agents may suffice, for examp with structural aggregate pigments intended for coating of pa for offset printing, higher levels of addition being prefer with composite pigments intended for filling of plastics, paper substrates to be saturated with solutions of organ resins.
• organic particulates e.g., polystyre pigments or polymer-emulsion adhesives, incorporated into t aggregate pigment structure modify the surface chemistry of t resultant pigments in an indirect fashion by forming a du matrix of polar/non-polar type.
• Carbon black and organic color dyes can be incorporated in structural aggregate pigments at levels ranging from 0.001% 0.25% and 0.001% to 5%, by weight, respectively.
• bo above materials have notoriously poor affinity toward polar su faces, such as mineral pigments or cellulosic fibers, they a retained and distributed uniformly within aggregate structur of pigments made with the aid of in-situ synthesized compl functional microgels used in practicing the present invention.
• Decorative gray papers totally opaque for all practic 3? purposes, can be manufactured with the aid of structural aggr gate filler pigments containing up to 0.25%, by weight, carbon black.
• Very attractive, "metallised” appearance paper surface can be obtained by incorporation both of metall and color pigments into structural aggregate filler pigments.
• Su irreversible attachment can be obtained by i corporation of suitable latex adhesives, along with organic dy and carbon black, into the structural aggregate pigments.
• T most effective immobilizing agents for carbon black and organ dyes were found to be the novel ultrafine polymer-emulsi adhesives to be discussed in more detail hereinafter.
• traces of carbon black a organic dyes detach from the mineral (polar) surface when co centrated slurries of structural aggregate pigments are expos to intensive shearing, becoming noticeable especially aft subsequent dilution and aging of the slurries.
• Coated papers for offs printing made with the aid of structural aggregate pigments co taining from 0.25% to 5%, by weight, of the ultrafine polyme emulsion adhesives were found to have better dry and wet coati pick, as well as higher blistering resistance, than analogo coatings made with the aid of conventional pigments.
• structural aggregate filler pigments containi these adhesives cause much less fiber debonding than conventio al fillers, this positive effect being amplified by hot cale dering of the filled paper.
• ultrafine polymer-emulsion adhesives along wit relatively fine particle size (essentially 100% finer than 5 u e.s.d.), high specific surface area (at least 50 m 2 /g) , strongl gelling minerals such as montmorillonite and bentonite, are th primary functional constituents of ultrahigh bulking pigment mentioned previously.
• the latter pigments are uniquely suite as fillers for uncoated printing papers, particularly newsprin and papers for ink-jet printers, as well as size-press coatin pigments, because of spectacular ink holdout resulting in excel lent print gloss.
• pigments are ideal carrie for ink-curing promoters (driers) , such as manganese, cobalt, lead naphthenates, which should be incorporated into these pi ments in proportions ranging from 0.1% to 5%, by weight.
• carriers such as manganese, cobalt, lead naphthenates
• Calciu -silico-aluminate, and other related, microgels us in practicing the present invention exert by themselves a pr nounced surface-chemical activity.
• cellulosic we filled with structural aggregate pigments made with the aid above microgels are virtually immune to aging phenomena relat to intrinsic acidity and light exposure.
• raw materia suitable for the manufacture of structural aggregate pigments extremely broad, encompassing, for example, virtually all typ of conventional "hydrous" kaolin clay products, as well as fi particle size calcined clay pigments derived from very fine pa ticle size kaolin clay feeds; precipitated calcium carbonat calcium silicate, calcium alurainate, calcium sulfate, hydrat alumina, hydrated silica, and silico-aluminates, with equivale spherical diameter ranging from 0.01 urn to 10 ym ⁇ naturall occurring calcium carbonate, gypsum, talcum, mont orillonit 3- * and bentonite, with equivalent spherical diameter ranging fro 0.1 im to 5 um; conventional (commercially available) titaniu dioxide pigments, as well as titanium dioxide products obtaine by special intensive comminution of commercial materials to in crease substantially the relative proportion of particles wit diameters between 0.2 urn and 0.4 um, and reduce the largest par ticles to a diameter
• each individual particle of titanium diox ide immobilized in the resultant aggregate structure may be sur rounded by up to 20,000, or even 30,000, particles of calciu silicate.
• T following Example I demonstrates the preparation of a simp structural aggregate pigment from a very fine particle si centrifugal fraction (100% finer than 2 um e.s.d.) of a lo quality Georgia clay crude, using specially developed laborato batch process intended to simulate continuous synthesis proce to be used preferably in large-scale plant operations.
• a 100 g batch of the above-mentioned very fine particle si kaolin clay fraction was made down into a slurry of about 7 solids, by weight.
• the batch of concentrated slurry was dilut subsequently to about 20% solids, by weight, and divided in two equal portions.
• a 5%-solids solution containing 2 g (d basis) of sodium silicate was added under agitation into o portion of above clay slurry.
• a 5%-solids soluti containing 2 g (dry basis) of sodium aluminate was added in the second portion of the above slurry.
• colloidal reactive sodium-silico-aluminate hydrosol (ani polyelectrolyte) was formed instantly by the interaction bet sodium silicate and sodium aluminate.
• the instantaneous flocculation of the system could be rec nized immediately by immersing a spatula in the slurry, with pigment floes being clearly visible in the thin layer of liq retained on the spatula.
• a narrow layer of clear supernat above the bulk of flocculated slurry formed after a couple minutes, while a thick crystal-clear layer of supernatant observed after a couple of hours.
• the flocculated slurry could be filtered right away, tho a controlled period of aging enhances the filtration rate alm invariably with all flocculated particulate systems.
• Dewater of the above slurry on a Buechner funnel at filter-cloth load of 2000 g/m 2 was extremely fast.
• 20%-sol slurry of above pigment having pH of 12 needed under above c ditions about 30 minutes for complete filtration and rinsing compared to 30 hours for a 20% solids slurry of non-aggrega raw material flocced with sulfuric acid to pH of 2.5. It worth noting that filtration of alkaline slurry of a very f particle size kaolin clay pigment would be totally impractica
• the rinsed and dried filter cake was pre-crushed and c minuted with the aid of conventional pulverizing equipment u routinely in the clay industry.
• the comminution regime defi by the number of passes through the pulverizer and the size screen openings, was chosen so as to maintain the dimensions largest particles in the resultant pigment product only sligh larger than they were in the raw material employed, limiting permanent aggregation effectively to the finer particulate fr tions present in the starting material.
• the optical performance of the structural aggregate pigm product obtained was rather impressive.
• the light-scatter coefficients of binderless coating films on black glass plat determined with the aid of techniques described by Kaliski TAPPI 53(11)1970, were 0.170 m 2 /g for the aggregate pigment compared with 0.050 m /g for the starting material (very f particle size kaolin clay) .
• a styrene-butadiene latex was us as the coating adhesive in proportion of 5 parts (dry weigh per 100 parts of total pigment.
• Analogous control coating fo mulation was prepared using above delaminated clay as the sol pigment.
• aqueous slurries of structural aggrega pigments diffe fundamentally from that of the high-glossing, very fine partic size, clays from which they were derived.
• structural aggrega pigments e.g., those described in Examples I and II
• mo coating clay products made from Georgia crudes can be made do with the aid of phosphate and/or polyacrylate dispersants in 70%-solids slurries, characterized by a more or less pronounc dilatancy.
• the structural aggregate pigments mentioned requi up to five-times higher levels of dispersants, yet, can be ma into slurries with a maximum solids content only slightly high than 60%.
• the slurries in question are highly thixotropic, fl most readily under shearing, and gel immediately when the shea ing forces are removed. This unique rheological behavior can sustained if above slurries are made down into properly form lated coating colors, or even relatively low-solids pigment sizepress formulations, which is not possible with the coati pigments of the present art.
• coating formul 4lo tions containing shear-thinning structural aggregate pigments the present invention can be applied at highest speeds attai able with the fastest, most advanced, coaters of the prese art.
• coating formulations of the above-mentioned ty have been applied on a commercial coater at speeds of near 5000 feet per minute, the empirical indications being that t coating speed could yet be increased very considerably.
• t ultrafine polymer-emulsion adhesive polybutylacrylate with average particle size below 55 nm and glass-transition te perature of -50°C
• Handsheets with dimensions of 30 cm x 30 cm ⁇ nd basis weig of 60 g/m 2 were prepared with the aid of laboratory mold usi furnish consisting of a 50:50 softwood/hardwood combinati
• the system was flocculated with alum at a rate of 20 lbs. ton of furnish, with a high-molecular-weight polyacrylam being used as the retention aid at a rate of 1 lb. per ton furnish.
• the acidity of the system was maintained at pH of with the aid of sulfuric acid.
• a set of filled handsheets was prepared with the aid of simple structural aggregate pigment mentioned above, furt referred to as the "principal" system, an analogous cont system being prepared with the aid of a delaminated clay.
• the brightness of unfilled handsheets was about 86% and not change appreciably with increasing filler levels both the principal as well as control systems.
• the opacity unfilled handsheets was 71%, increasing to 84.4% with the c trol system and 85.1% with the principal system at a fill loading level of 10%, by weight. Since optical properties filled sheets should be compared at equal sheet strength, much stronger principal sheets had to be brought up to a fill loading level of 16.5%, by weight, to reduce their strength the level of the control sheets containing only 10% of dela nated clay.
• opacity of principal sheets was 88.2%, i.e., 3.8 percenta points higher than that possible to obtain with control she of acceptable strength (i.e., containing 10%, by weight, delaminated-clay filler) .
• control she of acceptable strength i.e., containing 10%, by weight, delaminated-clay filler.
• the additional advantage reali with the aid of the simple structural aggregate filler -mentio was replacement of 130 lbs. of expensive chemical fibers per ⁇ 2, of paper product with incomparably less expensive and ecol cally preferable mineral matter.
• All types of structural aggretj ⁇ e filler pigments of present invention have, without exception, lower fiber-debon tendency than conventional filler pigments because of effec elimination of mineral fines.
• the above performance advan can be enhanced still further with the use of the novel ult fine polyacrylic emulsion adhesives, which are capable of exe ing a distinct filler/fiber cementing action when incorpora into the structure of aggregate filler pigments. This cement action is manifested first, however, when the adhesive cont reaches at least 2% of the total mass of aggregate pigments m of very fine particle size kaolin clays.
• the low fiber-debonding characteristics of structural agg gate pigments used in Example III can be used to full advant so in "high-ash" filling applications, referring to filler-loadin levels in excess of 30%, by weight, due to these pigments' ex tremely low abrasiveness.
• Multiple assays carried out with th aid of Einlehner's tester have shown that the abrasiveness men tioned ranges from 0 (zero) mg to 0.5 mg, qualifying thes pigments as perhaps the softest mineral fillers ever used in th paper industry.
• the structural aggregate pigments of the present inventio have significantly higher first-pass retention potential on paper machine, thus eliminating the need for prefl ⁇ cculatio high-ash paper filling applications. Moreover, ultrahigh le of first-pass retention, well in excess of 90%, can be atta with the aid of 0.1% to 5%, by weight, of synthetic an cellulosic microfibrils incorporated into structural aggre filler pigments.
• Cellulosic microfibrils suitable for the a purpose can be obtained with the aid of new technology devel by the Applicant and disclosed in co-pending patent applica (Serial No.: 07/165,759 ; Filed: March 9, 1988).
• the la technology involves cascade processing of cellulosic fib preferably cotton and well-fibrillating cellulosic pulps, sequential processing steps consisting of:
• Opacifying characteristic of structural aggregate pigmen of the present invention differs fundamentally from that of t pigments of the present art.
• the opacifying efficacies of t latter pigments including such powerful opacifiers as titani dioxide and calcined clay, deteriorate rapidly with increasi filler loading, at any level of filler addition.
• the reason f above performance deterioration is progressively denser crowdi of filler particles leading to avalanche-like flocculation, pa ticularly in the presence of abundant mineral fines with dime sions below 0.2 to 0.25 e.s.d.
• the opacity handsheets prepared under conditions similar to those describ in Example III increased by 4.8 percentage-points above th of unfilled control sheets when the relative content of titani dioxide in the sheet was increased from 0% to 1%, by weight, b 63 only by 0.6 percentage-points when above relative content w increased from 9% to 10%, by weight.
• th means that a curve representing opacity of Ti0 2 -filled shee as a function of loading level ascends initially very steepl but then flattens rapidly, as the filler-loading level of t sheet increases.
• composite pigments of the present invention whose miner fraction consists of 2% to 50%, by weight, of titanium dioxi pigments with the balance provided by the above-mentioned fi particle size calcined clays, were found to have excellent opt cal performance in paper filling and coating applicatio demonstrating enormous advantages of the instantaneous, indi criminate and complete flocculation (aggregation of fines) well as subsequent irreversible cementation, obtained with t aid of in-situ formed complex functional microgels used in pra ticing the present invention.
• composite pigmen consisting of 40% titanium dioxide and 60% fine particle si calcined clay, by weight.
• This composi pigment referred to in the following Example IV as "composi pigment (40/60)", as a full-fledged titanium-dioxide substitu in coating formulations for lightweight publication paper is i illustrated below:
• Example IV shows clearly that titanium dioxide pigment ca be substituted on "one-for-one" basis with composite pigments o the present invention containing only a fraction of the expen sive high-refractive index material. Similar one-for-one sub stitution of titanium dioxide with the same composite pigmen has been obtained in paper filling applications in a variety o paper products.
• composite pigment 40:60 Ti02:calcine clay
• the commercial titanium dioxide component wa first subjected to intensive comminution, e.g., with the aid o attrition grinder and zirconia balls with a diameter of approx 1 mm.
• intensive comminution e.g., with the aid o attrition grinder and zirconia balls with a diameter of approx 1 mm.
• the diameter of larges particles was reduced to p out 0.7 "im, bringing the dimension of the entire pigment population closer to those needed fo optimum light scattering.
• titanium dioxide pigment of the present art contain from 1.5% to 2%, by weight, of par ticles larger than 1 in diameter.
• Esthetically very pleasing, cream-colored, ultraopaque pap has been obtained with the aid of composite filler pigments co sisting of fine particle size calcined clay and naturally ocu ring rutile or anatase minerals comminuted intensively to average particle size smaller than 1
• intensively comminuted naturally occurring rutile a anatase incorporated into structural aggregate pigments beco practically useful at concentrations considerably lower than i by weight.
• the relative content " intensively comminuted rutile and anatase in structural compo ite pigments may be increased to 50%, by weight.
• aqueous dispersions carbon black must be de-agglomerated into elementary particl with the use of a special method developed by the Applicant, r ferred to in the following Claims as the "masterbatch.”
• an auxiliary aqueous dispersi of mineral pigment such as hydrous or calcined clay, or prec pitated silicate, is first prepared at highest possible soli attainable with the aid of "heavy-duty" industrial mixing kneading equipment.
• aqueous slurries of kaolin ci ?-hould be prepared at solids levels ranging from 78% to 82%, weight, which generates excessive heat and requires jacket cool ing of mixing vessels.
• Conventional aqueous dispersions of car bon black such as are possible to prepare by procedures of th present art, are then incorporated under maximum shearing int the auxiliary concentrated pigment slurries mentioned to brea down aggregates of elementary carbon black particles and for completely uniform pastes. Since these auxiliary slurries ma become fluid upon introduction of the conventional carbon blac dispersions, some additional dry pigment must be added to th system to restore its consistency to the previous level.
• the re ⁇ sultant, de-agglomerated, carbon black masterbatch is used in the preparation of structural aggregate pigments in essentially the same manner as other predispersed pigmentary raw materials.
• the opacifying power of structural aggregate pigments con ⁇ taining carbon black de-agglomerated by the above-described mas ⁇ terbatch method is demonstrated in the following example:
• a set of control handsheets, designated as Sheets A-l and A-2, filled with titanium dioxide pigment was prepared using a conventional acidic papermaking process.
• a parallel set of handsheets designated as Sheets B-1 and B-2, was filled with a composite pigment, synthesized by the procedure described in Example I, consisting of 40 parts titan ⁇ ium dioxide, 60 parts calcined clay, 0.12 parts carbon black (active basis) , and 2 parts ultrafine polybutylacrylate emulsion adhesive.
• the handsheets B-1 and B-2 were prepared with the aid of the alkaline papermaking process developed by the Applicant and disclosed in co-pending patent application (Serial No.: 0.7/165,759 ⁇ Filed: March 9, 1988 ).
• Example V The enormous opacifying power of the type of composite pigment described in Example V makes it particularly well suited fo newsprint filling applications.
• the basis weight of newsprint is declinin steadily from a 36 lbs/3000 sq.ft. standard prior to 1973 to 3 lbs/3000 sq.ft., and even 28 lbs/3000 sq.ft., in recent years Extensive research work is going on worldwide to lower t basis weight still further, preferably to 26 lbs/3000 sq.ft.
• newsprint opacity should range optimally from 92% to 95% adequate printing results, yet such high levels of opacity difficult to maintain systematically even with present newspr of heavier basis weight.
• a significant relaxation of newspr opacity specifications is unthinkable, however, in that t would necessitate a gigantic task of developing entirely printing technology.
• the general consensus is that futu ultralightweight, generation of newsprint will rely on the of the most opacifying filler systems available, at substanti ly higher loading levels than are employed presently.
• the b such filler system of the present art both from the standpoi of opacifying power and economy, consists of 30 % titanium di xide and 70 % calcined clay, by weight.
• the above system highly abrasive and debonding, however, and almost 35 .-poi brighter than present-day newsprint whose brightness ranges f 59% to 62%.
• Using Ti0 2 /calcined clay blend would thus necess tate extensive dying-back of the sheet with the aid of organ dyes which, as previously mentioned, drastically reduce ne print's ink holdout when deposited on cellulosic fibers, t detrimental esthetic side effects notwithstanding.

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• 1990
  • 1990-03-28 AU AU53532/90A patent/AU649221B2/en not_active Ceased
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