CA1306085C - Kaolinite aggregation using organo-silicon compounds - Google Patents
Kaolinite aggregation using organo-silicon compoundsInfo
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- CA1306085C CA1306085C CA000581316A CA581316A CA1306085C CA 1306085 C CA1306085 C CA 1306085C CA 000581316 A CA000581316 A CA 000581316A CA 581316 A CA581316 A CA 581316A CA 1306085 C CA1306085 C CA 1306085C
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- kaolin
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- clay
- silicon compound
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Abstract
ABSTRACT
KAOLINITE AGGREGATION USING ORGANO-SILICON COMPOUNDS
A particulate kaolin pigment which enhances gloss and printability properties when used as a coating pigment for paper and enhances light scattering and opacifying properties when incorporated as a filler in paper, is obtained by mixing a fine particle kaolin with an aggregating agent comprising an organic silicon compound such as tetramethoxy silane or tetraethoxy silane.
KAOLINITE AGGREGATION USING ORGANO-SILICON COMPOUNDS
A particulate kaolin pigment which enhances gloss and printability properties when used as a coating pigment for paper and enhances light scattering and opacifying properties when incorporated as a filler in paper, is obtained by mixing a fine particle kaolin with an aggregating agent comprising an organic silicon compound such as tetramethoxy silane or tetraethoxy silane.
Description
~ ~3060~35 ~e~
Raolinite Aggregation Using Organo-Silicon Compounds Field of the Invention This application relates to the preparation of chemically aggregated kaolinite using organo-silicon compounds.
The products are useful as fillers and coatings for paper.
S Background of the Invention Kaolinite based pigments are commonly used in paper industries for paper filling and paper coating applications. In general, the objectives of using the pigment are to improve paper qualities, such as opacity, brightness, smoothness, printing, porosity, ~urface coverage, light scatter, and to reduce the cost of paper manufacturing.
Both the brightness characteristics of the given kaolin and the opacifying properties of same when incorporated as a filler in paper, may be quantitatively related to a property of the filler identified as the ~scattering coefficient S.~ The said parameter, i.e., the scattering coefficient S of a given filler pigment, is a property well-known and extensively utilized in the paper technology art, and has been the subject of numerous technical papers and the like. The early exposition of such measurements was made by Xubelka and Munk, and is reported in Z. Tech Physik 12:539 t1931~. Further citations to the appli-cable measurement techniques and detailed definitions of the said scattering coefficient are set forth at numerous places in the patent and technical literature. Reference may usefully be had .~
~3~6~S
in this connection, e.g., to U.S. patents Nos. 4,026,726 and 4,028,173. In addition to the citations set forth in these patents, reference may further be had to Pulp and Paper Science Technology Vol. 2 "Paper," Chapter 3, by H. C. Schwalbe (McGraw-Hill Book Company, N.Y.).
In a filled paper, higher light scattering is therefore important. Increased light scatter allows paper to look more opaque without increasing light absorption. The use of pigment with a higher light scattering coefficient allows reduction in either the basis weight or amount of filler required to achieve targeted properties, for example, opacity and brightness. Tradi-tionally, this has been achieved using titanium dioxide, calcined clays and precipitated calcium carbonate. The relatively higher light scattering of titanium dioxide is due to higher refractive index. Higher light scatter observed with calcined kaolin and precipitated calcium carbonate is believed to be due to the intrinsic porous structure developed during the process of manu-facturing of these pigments. See McConnell et al, U.S. Patent No. 4,381,948.
ln general, the attempt to increase light scatter by modification of kaolinite mineral also induces some increase in pore void volume. In addition, such modification can produce pigments with particle siz~ distribution in a fairly narrow range.
For example, calcining of fine kaolinite above its dehydroxyla-tion point can produce a product with increased pore void volume.
~3a~
In u.S. Patent No. 4,820,554 issued April 11, 1989 similar aggregation is achieved chemically by reacting fine kaolinite clay with rapidly hydrolyzing metal chlorides.
The acidic by-product of this reaction may be neutralized with gaseous ammonia. The light scattering coefficient and pore void volumes of these clays are significantly higher than the starting kaolinite material. Marginal increase in light scatter (generally less than 10 units) may be induced by mixing kaolinite particles of dif~erent size or by chemical flocculation. However, these structures are generally unstable and would break down under high shear stress of paper making or paper coating.
Aside from use as fillers, the aggregated pigments are used in paper coating to improve surface coverage. The application of such pigments can lead to a smoother surface, higher porosity, gloss and print properties. In the said patent application a chemically aggregated kaolin pigment is shown to significantly ircrease coated sheet properties, especially paper and print gloss.
In more detail, in U.S. Patent No. 4,381,948 to A. D. McConnell et al, a calcined kaolin pigment is disclosed and a method for manufacture of same. The said pigment consists of porous aggregates of kaolin platelets, and exhibits exceptionally high light scatt~ring characteristics when incorporated as a filler in paper.
This pigment, which substantially corresponds to the - commercially available product ALPHATEX~ of the present assignee, E.C.C. America Inc. (Atlanta, Georgia) is prepared by ...
~3~ 5 first blunging and dispersing an appropriate crude kaolin to form an aqueous dispersion of same. The blunged and dispersed aqueous slurry is subjected to a particle size separation from which there is recovered a slurry of the clay, which includes a very fine particle size; e.g. substantially all particles can be smaller than 1 micrometer E.S.D. The slurry is dried to produce a relatively moisture-free clay, which i5 then thoroughly pul-verized to break up agglomerates. This material is then used as a feed to a calciner; such feed is calcined under carefully con-trolled conditions to typical temperatures of at least 900 C.The resulting product is cooled and pulverized to provide a pig-ment of the porous high light scattering aggregates of kaolin platelets as described.
Calcined kaolin products, including those of the afore-mentioned ALPHATEX type, are seen to be manufactured by rela-tively complex techniques involving a multiplicity of steps, including specifically a calcining step, plus various preparatory steps and post-calcining steps. Thus, the said product is rela-tively expensive to produce; and requires considerable investment in complex apparatus and the like -- e.g. highly regulated cal-ciners, etc. It can indeed be noted that the conditions of pre-paration of these materials must be very careully controlled in order to keep abrasion acceptably low in the calcined product.
For example! the calcination operation tends per se to produce an abrasive product -- in consequence of overheating -- if great care is not taken to preclude such a result.
: L3~6~
It is further to be noted that in order to produce a low abrasion calcined product, the particle size in the feed to the calciner must be carefully controlled -- even a relatively small increase in coarseness of such feed can have very marked detrimental effect on Valley abrasion.
In U.S. Patent 4,820,554 issued April 11, 1989, a process is disclosed in which a fine particle size kaoline is reacted in particulate form with a metal chloride, such as silicon tetrachloride, to form a chemically aggregated structured kaolin pigment. The metal chloride may be one or more of the chlorides having the general formula MClx, where M is Si, Ti or Al; and X is 3 or 4 depending on the valence of M. Heating may optionally be used to shorten the reaction time. When so used, temperatures generally will not, however, exceed about 150C. In order to complete the polymerization and condensation which is thought to occur, it is preferable to age the resulting product for a period, typically at least three days. In another aspect of that process, additional improvements in the products are found to occur by the addition of ammonia to the combined kaolin and metal chloride.
Thus said patent application describes methods of preparing chemically aggregated kaolinite mineral using very reactive metal chlorides such as silicon tetrachloride and titanium tetrachloride. The application of such reactive metal chloride leads to aggregated products that give enhanced optical and printability properties for both filled and coated papers.
13~6~1~5 However, due to the nature of the aggregating chemical, very specialized equipment and processing steps are required. In addition, the resultant by-products are difficult to remove by ordinary methods. In this invention, similar aggregates may be S produced by reaction with organo-silicon compounds that are non-corrosive and produce no so:Lid by-products~
It is known from U.S. patent 3,567,6~0 to Joseph Iannicelli, assigned to J.M. Huber Corporation, issued March 2, 1971, that mercaptopropyl silanes having the formula:
~ORl Z ' S X Si --OR2 ~1 ) wherein Z is selected from the group consisting of hydrogen, cation, alkyl, aryl, alkylaryl, arylalkyl and deriva-tives thereof; X is selected from the group consisting of alkyl, alkylaryl, and arylalkyl; and Rl, R2 and R3 are selected from the group consisting of hydrogen, cation and alkyl, are suitable for moclifying kaolin clays to enable them to be used as rein-forcing illers for elastomers. In fact the thus modified clays have been the candidates of choice for such fillers in commerce.
It may be noted that in the Iannicelli disclosure, only the trialkoxy mercaptopropyl silanes are considered. Blends of these mercapto organosilanes with amino organosilanes are also dis-closed.
In U.S. Patent No. 3,364,059 to Mar~occhi, a method for treating glass fibers to improve their bonding relationship ~7- ~3~t~8~ -to rubbers comprises treating them with a silane containing a thio group.
According to the present invention, the thio group and the amino group are not required. Sulfur-free and nitrogen-free organic silicon compounds are employed.
In U.S. patent 3,834,92~1 to Thomas A. Grillo, assigned to J.M. Huber Corporation, an amino organosilane is added to a high solids content pigment dispersion or slurry to change the slurry form into a thick, flocculated and plastic-type that is suitable for extrusion and drying. Because athick, cake-like product is formed, the amino organosilane and pigment dispersion are preferably mixed or blended directly in a solids mixing apparatus such as an extruder, designed to extrude the plastic mass in the form of a compacted rad type body which may be fed directly into a drier. The products are useful as a filler for polyurethanes. As can be seen, the described treatment is for the different purpose of forming a flocculated, plastic mass of the kaolin, not for the purpose of aggregat.ng fine kaolin particles to form aggregated fine kaolin particles.
In U.S. patent 3,894,882 to Robert B. Takewell et al, assigned to J.M. Huber Corporation, a rotating pelletizing drum is used to form pellets from clay sucn as kaolin clay. To avoid the problem of dust, a wetting liquid is introduced into the drum, preferably steam or steam~water. The steam adds heat to the pellets to aid in drying them. There is an incidental 131~
mention of using "other suitable wetting liquids", an extensive list being given which includes silanes.
In accordance with the foregoing, it may be regarded as an object of the present invention to provide an aggregated kaolin pigment product which possesses improved pigment bulk, porosity and light scattering characteristics, and hence is useful as a bulking pigment for coating of paper and paper board, and which may also be used as an opacifier and light scattering .iller for paper and paper board as well as in other paper manufacturing applications.
It is also an object of the invention to provide a pigment product of the foregoing character which is prepared without calcination and therefore without subjecting the kaolinite to high temperatures, and which accordingly possesses low abrasiveness in accordance with the kaolinite feed from which it is produced.
Another object of the present method is to demonstrate application of substantially dry kaolin pigment in aggregation.
Yet another object is to demonstrate aggregation of kaolinite particle by dry processing routes.
Yet another object is to demonstrate use of aggregated pigment made by the present invention in paper filling to enhance optical properties.
Yet another object is to show the application of such pigment in light weight coatings.
-9- ~3~
Yet another object is to show the production of the pigment in the presence of an aggregation enhancer such as calcium chloride.
It is a further object of the present invention to S produce pigment that is free of soluble salts.
It is yet another object of the present invention to produce a pigment that, as a consequence of aggregation, can be processed to a slurry at a solids content higher than 60 by weight without unduly poor rheological consequences.
It is yet another object of the present invention to provide a process wherein aggregation efficiency, i.e. light scatter, is improved by application of gaseous ammonia.
It is an object of the present invention to produce aggregated kaolinite pigment with minimum steps in producing lS said pigment.
It is also an object of the present invention to produce aggregated kaolinite pigment at relatively low cost compared with available such products.
Summary of the Invention The present invention comprises a method of producing aggregated kaolin pigments, specifically structured kaolin pigments, using organo-silicon compounds either singly or in combination. In general, the compounds may be selected from the following:
-lo- ~3Q~085 Symmetric Compounds OR
RO-Ii-OR
OR
R=CH3~ C2H5 C3H7, n-C4Hg, sec-c4H9~ C6H5 Asymmetric Compounds OR OR R
RO-Si-X Ro-Si-R RO-Si-R
OR OR OR
R=C2H5 X = Cl, Br R = H
In a typical process, substantially dry kaolin mineral is treated with an effective amount of an organo-silicon compound such as silanes having the formula (RO)4Si, where R is a lower alkyl group of 1 to 4 carbon atoms, e.g., methyl (CH3), or ethyl (CH3CH2). The R groups in the silane can be the same or differ-ent. The resulting products exhibit increased light scatter, improved wet void volume and bulk. The aggregates seem to have a permanent structure that is strong enough to withstand the high shear forces of paper making and paper coating.
Aggregation enhancing chemicals, which may optionally be used, comprise alkaline earth metal chlorides and lithium chloride. Amounts used of this aggregation enhancing agent may be in the range of 0.05 to 3.0~, typically 0.05 to 2% by weight of the salt based on the weight of the dry kaolin.
Raolinite Aggregation Using Organo-Silicon Compounds Field of the Invention This application relates to the preparation of chemically aggregated kaolinite using organo-silicon compounds.
The products are useful as fillers and coatings for paper.
S Background of the Invention Kaolinite based pigments are commonly used in paper industries for paper filling and paper coating applications. In general, the objectives of using the pigment are to improve paper qualities, such as opacity, brightness, smoothness, printing, porosity, ~urface coverage, light scatter, and to reduce the cost of paper manufacturing.
Both the brightness characteristics of the given kaolin and the opacifying properties of same when incorporated as a filler in paper, may be quantitatively related to a property of the filler identified as the ~scattering coefficient S.~ The said parameter, i.e., the scattering coefficient S of a given filler pigment, is a property well-known and extensively utilized in the paper technology art, and has been the subject of numerous technical papers and the like. The early exposition of such measurements was made by Xubelka and Munk, and is reported in Z. Tech Physik 12:539 t1931~. Further citations to the appli-cable measurement techniques and detailed definitions of the said scattering coefficient are set forth at numerous places in the patent and technical literature. Reference may usefully be had .~
~3~6~S
in this connection, e.g., to U.S. patents Nos. 4,026,726 and 4,028,173. In addition to the citations set forth in these patents, reference may further be had to Pulp and Paper Science Technology Vol. 2 "Paper," Chapter 3, by H. C. Schwalbe (McGraw-Hill Book Company, N.Y.).
In a filled paper, higher light scattering is therefore important. Increased light scatter allows paper to look more opaque without increasing light absorption. The use of pigment with a higher light scattering coefficient allows reduction in either the basis weight or amount of filler required to achieve targeted properties, for example, opacity and brightness. Tradi-tionally, this has been achieved using titanium dioxide, calcined clays and precipitated calcium carbonate. The relatively higher light scattering of titanium dioxide is due to higher refractive index. Higher light scatter observed with calcined kaolin and precipitated calcium carbonate is believed to be due to the intrinsic porous structure developed during the process of manu-facturing of these pigments. See McConnell et al, U.S. Patent No. 4,381,948.
ln general, the attempt to increase light scatter by modification of kaolinite mineral also induces some increase in pore void volume. In addition, such modification can produce pigments with particle siz~ distribution in a fairly narrow range.
For example, calcining of fine kaolinite above its dehydroxyla-tion point can produce a product with increased pore void volume.
~3a~
In u.S. Patent No. 4,820,554 issued April 11, 1989 similar aggregation is achieved chemically by reacting fine kaolinite clay with rapidly hydrolyzing metal chlorides.
The acidic by-product of this reaction may be neutralized with gaseous ammonia. The light scattering coefficient and pore void volumes of these clays are significantly higher than the starting kaolinite material. Marginal increase in light scatter (generally less than 10 units) may be induced by mixing kaolinite particles of dif~erent size or by chemical flocculation. However, these structures are generally unstable and would break down under high shear stress of paper making or paper coating.
Aside from use as fillers, the aggregated pigments are used in paper coating to improve surface coverage. The application of such pigments can lead to a smoother surface, higher porosity, gloss and print properties. In the said patent application a chemically aggregated kaolin pigment is shown to significantly ircrease coated sheet properties, especially paper and print gloss.
In more detail, in U.S. Patent No. 4,381,948 to A. D. McConnell et al, a calcined kaolin pigment is disclosed and a method for manufacture of same. The said pigment consists of porous aggregates of kaolin platelets, and exhibits exceptionally high light scatt~ring characteristics when incorporated as a filler in paper.
This pigment, which substantially corresponds to the - commercially available product ALPHATEX~ of the present assignee, E.C.C. America Inc. (Atlanta, Georgia) is prepared by ...
~3~ 5 first blunging and dispersing an appropriate crude kaolin to form an aqueous dispersion of same. The blunged and dispersed aqueous slurry is subjected to a particle size separation from which there is recovered a slurry of the clay, which includes a very fine particle size; e.g. substantially all particles can be smaller than 1 micrometer E.S.D. The slurry is dried to produce a relatively moisture-free clay, which i5 then thoroughly pul-verized to break up agglomerates. This material is then used as a feed to a calciner; such feed is calcined under carefully con-trolled conditions to typical temperatures of at least 900 C.The resulting product is cooled and pulverized to provide a pig-ment of the porous high light scattering aggregates of kaolin platelets as described.
Calcined kaolin products, including those of the afore-mentioned ALPHATEX type, are seen to be manufactured by rela-tively complex techniques involving a multiplicity of steps, including specifically a calcining step, plus various preparatory steps and post-calcining steps. Thus, the said product is rela-tively expensive to produce; and requires considerable investment in complex apparatus and the like -- e.g. highly regulated cal-ciners, etc. It can indeed be noted that the conditions of pre-paration of these materials must be very careully controlled in order to keep abrasion acceptably low in the calcined product.
For example! the calcination operation tends per se to produce an abrasive product -- in consequence of overheating -- if great care is not taken to preclude such a result.
: L3~6~
It is further to be noted that in order to produce a low abrasion calcined product, the particle size in the feed to the calciner must be carefully controlled -- even a relatively small increase in coarseness of such feed can have very marked detrimental effect on Valley abrasion.
In U.S. Patent 4,820,554 issued April 11, 1989, a process is disclosed in which a fine particle size kaoline is reacted in particulate form with a metal chloride, such as silicon tetrachloride, to form a chemically aggregated structured kaolin pigment. The metal chloride may be one or more of the chlorides having the general formula MClx, where M is Si, Ti or Al; and X is 3 or 4 depending on the valence of M. Heating may optionally be used to shorten the reaction time. When so used, temperatures generally will not, however, exceed about 150C. In order to complete the polymerization and condensation which is thought to occur, it is preferable to age the resulting product for a period, typically at least three days. In another aspect of that process, additional improvements in the products are found to occur by the addition of ammonia to the combined kaolin and metal chloride.
Thus said patent application describes methods of preparing chemically aggregated kaolinite mineral using very reactive metal chlorides such as silicon tetrachloride and titanium tetrachloride. The application of such reactive metal chloride leads to aggregated products that give enhanced optical and printability properties for both filled and coated papers.
13~6~1~5 However, due to the nature of the aggregating chemical, very specialized equipment and processing steps are required. In addition, the resultant by-products are difficult to remove by ordinary methods. In this invention, similar aggregates may be S produced by reaction with organo-silicon compounds that are non-corrosive and produce no so:Lid by-products~
It is known from U.S. patent 3,567,6~0 to Joseph Iannicelli, assigned to J.M. Huber Corporation, issued March 2, 1971, that mercaptopropyl silanes having the formula:
~ORl Z ' S X Si --OR2 ~1 ) wherein Z is selected from the group consisting of hydrogen, cation, alkyl, aryl, alkylaryl, arylalkyl and deriva-tives thereof; X is selected from the group consisting of alkyl, alkylaryl, and arylalkyl; and Rl, R2 and R3 are selected from the group consisting of hydrogen, cation and alkyl, are suitable for moclifying kaolin clays to enable them to be used as rein-forcing illers for elastomers. In fact the thus modified clays have been the candidates of choice for such fillers in commerce.
It may be noted that in the Iannicelli disclosure, only the trialkoxy mercaptopropyl silanes are considered. Blends of these mercapto organosilanes with amino organosilanes are also dis-closed.
In U.S. Patent No. 3,364,059 to Mar~occhi, a method for treating glass fibers to improve their bonding relationship ~7- ~3~t~8~ -to rubbers comprises treating them with a silane containing a thio group.
According to the present invention, the thio group and the amino group are not required. Sulfur-free and nitrogen-free organic silicon compounds are employed.
In U.S. patent 3,834,92~1 to Thomas A. Grillo, assigned to J.M. Huber Corporation, an amino organosilane is added to a high solids content pigment dispersion or slurry to change the slurry form into a thick, flocculated and plastic-type that is suitable for extrusion and drying. Because athick, cake-like product is formed, the amino organosilane and pigment dispersion are preferably mixed or blended directly in a solids mixing apparatus such as an extruder, designed to extrude the plastic mass in the form of a compacted rad type body which may be fed directly into a drier. The products are useful as a filler for polyurethanes. As can be seen, the described treatment is for the different purpose of forming a flocculated, plastic mass of the kaolin, not for the purpose of aggregat.ng fine kaolin particles to form aggregated fine kaolin particles.
In U.S. patent 3,894,882 to Robert B. Takewell et al, assigned to J.M. Huber Corporation, a rotating pelletizing drum is used to form pellets from clay sucn as kaolin clay. To avoid the problem of dust, a wetting liquid is introduced into the drum, preferably steam or steam~water. The steam adds heat to the pellets to aid in drying them. There is an incidental 131~
mention of using "other suitable wetting liquids", an extensive list being given which includes silanes.
In accordance with the foregoing, it may be regarded as an object of the present invention to provide an aggregated kaolin pigment product which possesses improved pigment bulk, porosity and light scattering characteristics, and hence is useful as a bulking pigment for coating of paper and paper board, and which may also be used as an opacifier and light scattering .iller for paper and paper board as well as in other paper manufacturing applications.
It is also an object of the invention to provide a pigment product of the foregoing character which is prepared without calcination and therefore without subjecting the kaolinite to high temperatures, and which accordingly possesses low abrasiveness in accordance with the kaolinite feed from which it is produced.
Another object of the present method is to demonstrate application of substantially dry kaolin pigment in aggregation.
Yet another object is to demonstrate aggregation of kaolinite particle by dry processing routes.
Yet another object is to demonstrate use of aggregated pigment made by the present invention in paper filling to enhance optical properties.
Yet another object is to show the application of such pigment in light weight coatings.
-9- ~3~
Yet another object is to show the production of the pigment in the presence of an aggregation enhancer such as calcium chloride.
It is a further object of the present invention to S produce pigment that is free of soluble salts.
It is yet another object of the present invention to produce a pigment that, as a consequence of aggregation, can be processed to a slurry at a solids content higher than 60 by weight without unduly poor rheological consequences.
It is yet another object of the present invention to provide a process wherein aggregation efficiency, i.e. light scatter, is improved by application of gaseous ammonia.
It is an object of the present invention to produce aggregated kaolinite pigment with minimum steps in producing lS said pigment.
It is also an object of the present invention to produce aggregated kaolinite pigment at relatively low cost compared with available such products.
Summary of the Invention The present invention comprises a method of producing aggregated kaolin pigments, specifically structured kaolin pigments, using organo-silicon compounds either singly or in combination. In general, the compounds may be selected from the following:
-lo- ~3Q~085 Symmetric Compounds OR
RO-Ii-OR
OR
R=CH3~ C2H5 C3H7, n-C4Hg, sec-c4H9~ C6H5 Asymmetric Compounds OR OR R
RO-Si-X Ro-Si-R RO-Si-R
OR OR OR
R=C2H5 X = Cl, Br R = H
In a typical process, substantially dry kaolin mineral is treated with an effective amount of an organo-silicon compound such as silanes having the formula (RO)4Si, where R is a lower alkyl group of 1 to 4 carbon atoms, e.g., methyl (CH3), or ethyl (CH3CH2). The R groups in the silane can be the same or differ-ent. The resulting products exhibit increased light scatter, improved wet void volume and bulk. The aggregates seem to have a permanent structure that is strong enough to withstand the high shear forces of paper making and paper coating.
Aggregation enhancing chemicals, which may optionally be used, comprise alkaline earth metal chlorides and lithium chloride. Amounts used of this aggregation enhancing agent may be in the range of 0.05 to 3.0~, typically 0.05 to 2% by weight of the salt based on the weight of the dry kaolin.
3~
Typically, feed moisture is in the range of 1 to 2~, preferably 1.0 to 1.75% by weight of the feed clay. The most preferred range is 1.5 to 1.75~ by weight of the clay.
The amount of organic silicon compound may range from S 0.1 to 3.0%, preferably from 0.2 to 2.0~ by weight of dry kaolin.
Brief Description of the Drawings In FIGURE 1 are compared the particle size distribu-tion of the starting material and an aggregated product prepared using 1~ tetramethoxysilane.
In FIGURE 2 are plotted the brightness of coated sheets using aggregated pigments and a control consisting of fine clay and calcium carbonate.
In FIGURE 3 are plotted the opacity of coated sheets using aggregated pigments and a control consisting of fine clay and calcium carbonate.
In FIGURE 4 are plotted the paper gloss of coated sheets using aggregated pigments and a control consisting of fine clay and calcium carbonateO
In FIGURE 5 are plotted the print gloss of coated sheets using aggregated pigments and a control consisting of fine clay and calcium carbonate.
In FIGURE 6 are plotted the litho print gloss of coated sheets using aggregated pigments and a control consist-ing of fine clay and calcium carbonate.
In FIGURE 7 is plotted the effect of feed clay moisture on the light scattering characteristic of aggregated -12- ~3~ 85 kaolinite prepared using 1% tetramethoxysilane.
In FIGURE 8 are plotted the percent wet void volume of aggregated pigments vs. amounts of the aggregating agent.
In FIGURE 9 are plotted the light scatter of aggre-gated pigment vs. amounts of aggregating agent.
In the ensuing description, all scattering data are normalized by comparison to the scattering coefficient of samples of the aforementioned Alphatex~. Ideally in a study of the present nature, the same batch of beaten pulp should be used throughout. As this is not practical, the method adopted was to fill one set of sheets in each series of tests using the same Alphatex~ from series to series. Statistically, the Alphatex~ filled samples at 10~ filler had a scattering coeffi-cient of 680 cm2/gram, and in each series in which Alphatex~
differed from 680, the scattering coefficients of the experi-mental samples were accordingly adjusted proportionally to the adjustments which the Alphatex~-containing paper required to bring its value to 680 cm2/gram. This procedure, which was used in subsequent examples, is from time to time referred to in the specification as "normalizingN the scattering coefficients.
Detailed Descri~tion General Methods of PreParation of Feed Cla~
This corresponds to preparation of the commercial product Betagloss~ of the assignee E.C.C. America Inc. (Atlanta, Georgia).
~10~8~
The starting crude material was a blend of crude kao-lins, which were derived from northeast Georgia, and which were comprised of very fine particle size materials. The GE bright-ness of the said crude was in th~e range of 82 to 37. In all instances in this specification it will be understood that brightness values are obtained according to the standard specifi-cation established by TAPPI procedure T-646 os-75.
The crude clays were beneficiated according to the gen-eral practice used in kaolinite processing industries. The bene-ficiated clays were classified by centrifugation to 94% less than2 micrometer E.S.D. (equivalent spherical diameter). The classi-fied clays were flocculatsd using 0.25~ by weight of aluminum sulfate and adjusting the pH to 3.5 with sulfuric acid. The flocculated kaolinites were filtered. The significantly dried (about 20% moisture remains) kaolinites were redispersed with 0.25~ by weight of sodium polyacrylate and the pH adjusted to about 7Ø The redispersed kaolinite was spray dried.
This method of preparing fsed clays is general and may be varied, particularly if so pointed out in specific Examples; the main variations are differences in particle si~e distribution and the addition of calcium carbonate.
Standard Method of Relative Sedimentation Volume Measurement The relative sedimentation volume of treated and start-ing material was measured to determine the exten~ and nature of aggregation. In the procedure, a nearly 55% solids slurry of pigment was prepared that contained 0.3 milliliter of sodium 31~
polyacrylate. This slurry was then spun at 7000 rpm for 45 min-utes. The sediment volume was calculated using dry weight of clay, wet weight of clay, and calculating volume of clay using density of dry clay of 2.6g/ml.
The invention is demonstrated in the following examples which are intended to be illustrative but not limitative.
Example 1 The starting feed clay was prepared from a blend of two fine Northeastern crude clays from Georgia. The crude clays were refined by common commercial beneficiation methods. The refined clay was classified to 96~ less than 2 micrometer E.S.D.
The classified clay was blended with ground calcium carbonate JS
(Carbital -90) at 3% weight of dry kaolinite. The blend was spray dried and pulverized using a pulverizer manufactured by Mikropul Corporation. This clay will be referred to as Feed Clay-I.
75 9. of substantially dry powder, moisture 0.85~, of Feed Clay-I was treated with 1% by weight of tetramethoxy-silane, supplied by Petrarch Chemical Co., with vigorous mixing in a Waring blender. Once the mixing of powder with liquid was completed, the clay was allowed to mix for an additional 1.5 minutes. Excess silane and resultant methanol as a by-product were removed by subjecting the clay to vacuum (nearly 30 torr). The above process with tetramethoxysilane was repeated once and the final product was allowed to dry at 150C for fifteen minutes.
~n~
The particle size distributions of the starting Feed Clay-I and the final product are illustrated in Fig. 1. The particle size distribution indicates formation of a structured aggregate with very narrow particle size distribution.
Handsheets were prepared using the above aggregated clay from bleached sulfite pulp. The sheets were filled at three filler loadings. The reflectivity of the handsheets was measured and converted to light scatter according to a modified Kabulka-Munk equation. The normalized light scatter of sheets filled at 10% filler loading with this product was 578 cm2/g.
This is a gain of 60 scatter units from untreated Feed Clay-I.
The intraparticle porosity of the pigment, given as percent wet void volume and determined by the relative sedimentation method (RSV) was 57.3%. This is an increase of about 17 percentage units from the feed clay. The increase in wet void volume indicates the formation of aggregate structure and development of the permanent porosity.
Example 2 The process and the chemical used were essentially identical to Example 1, except that the feed was a fine commercial clay, Betagloss. The particle size distribution and moisture of this feed clay were 94% less than 2 micro-meter, and 0.85% respectively. The normalized light scatter of a sheet filled with the final aggregated product, at 10%
filler loading, was 562 cm2/g. Wet void volume of the product determined by RSV was 56.4%, an increase of about 16~ percentage units over the feed clay.
-16- ~3~6~8~ -Example 3 The feed clay, aggreclating agent and the mixing process were essentially identical to that of Example 2, except that the clay was treated with 0.45~ by weight of ammonia gas following each evacuation step. The normalized light scatter of a sheet filled with this pigment, at 10% filler loading, was 550 cm2/g.
The wet void volume of the product, determined by RSV, was 56.7~. Wet void volume and scatter respectively are about 16 percentage units and 30 scatter units higher than the feed clay.
Example 4 In this example Feed Clay-II was prepared by mixing 3% ground calcium carbonate with previously spray dried and pulverized ~etagloss followed by drying at 150C for 15 minutes. The moisture of this feed clay-II was 0.6~% by weight.
The aggregating chsmical and the treatment process were essentially identical to Example 1. The normalized light scatter of a sheet filled with this pigment at 10~ filler loading was 585 cm2/g, which is an increase of about 65 units over the ~eed clay. Wet void volume is about 16 percentage units higher than the feed clay, thus 55.9~.
Example 5 ~eed Clay-II was treated by the es~entially identical method and chemicals described in Example 3. The normalized light scatter o~ a sheet filled with this pigment at 10~ filler loading was 5~ cm2/g. There was an about 16.1 percentage units increase in wet void volume over the feed clay following the chemical aggregation, thus 56.1~.
6~5 Exa_ple 6 The feed clay and the process of treatment were essentially identical to the method described in Example 2, except that the aggregating agent was an organo-silicon compound containing ethoxy groups. (CH3CH2O)4Si. The normal-ized light scatter of a sheet filled with this pigment at 10 filler loading was 547 cm2/g. The wet void volume of the product by RSV was 54.1%. Upon chemical aggregation, wet void volume and light scatter increased by about 14 percentage units and 27 scatter units respectively over the feed clay.
Example 7 The feed clay, aggregating agent, and the treatment process all were essentially identical to the method described in Example 6 except that the clay was exposed to 0.4S~ by weight of ammonia immediately following the evacuation step as described~
in Example 3. The normalized light scatter o a sheet filled with this pigment at 10% filler loading was 544 cm?/g. The wet void volume determined by RSV of the product was 54.9%.
Example 8 The feed clay and process were essentially identical to the method described in Example 4 except that the aggre~
gating chemical was tetraethoxysilane, (C~3CH2O)4Si. The normal-ized light scatter of a sheet filled with this pigment at 10~
filler loading was 570 cm2/g. The relative sedimentation method showed the product to have 52.1 percent wet void volume. The increases in llght scatter and wet void volume amount to 50 : ~ ~
~3~ 85 scatter units and about 12 percentage units over the feed clay, respectively.
Exc~m~le 9 The process and aggregating chemical were essentially S identical to the method described in Example 7 except that Feed Clay-II was the starting material. The normalized light scatter of a sheet filled with this structured aggregated clay, at 10%
filler loading, was 584 cm2/g. In addition, the wet void volume determined by RSV was 54.4~, an increase of about 14 percentage units over the feed clay.
Example 10 The process, aggregating chemical and the feed clay all were essentially identical to the method described in Example 1, except that the moisture content of the feed clay was such that the molar ratio of water to silane was 9.69, which is equivalent to a moisture content of the feed clay of about 1.11~ by weight. The relative sedimentation method showed the product to have 57.5 percent wet void volume.
This product was used to determine coated sheet properties of light weight coated offset grade paper. In the coating formulationj 30 parts of regular coating pigment were replaced with this product. The typical formulation and rele-vant formulation properties are provided in Table 1.
Almost all of the coated sheet properties improved by application of this aggregated clay, for example, sheet gloss, print gloss and opacity. These coated sheet properties are ~1 30~Z 35 .
illustrated in Figures 2 through 6. The properties, i.e.
brightness, opacity, gloss, print gloss, and litho print gloss are compared with a common offset control formulation.
Exan!ple 11 The feed clay and the process were essentially identical to the method described in Example 10, except that the aggregating chemical was (CH3C~2O)4Si, tetraetho~ysilane.
The relative sedimentation method showed the product to have 51.9 percent wet void volume, an improvement of nearly 12 percentage units over untreated feed clay.
As in Example 10, this pigment was evaluated in a paper coating application. Once again, significent improvement of coated sheet properties is observed with this aggregated structure pigment. The essential coated sheet properties, e.g.
brightness, opacity, gloss, print gloss, and litho print gloss are illustrated in Figures 2 to 6.
Example 12 It is postulated that the hydrolysis, and subsequent polymerization of the hydrolyzed products, of the orsano-silicon compound, e.g. silane, would depend on the availability of free moisture. In the presence of excessive moisture it might be possible that the hydrolyzed product would precipitate as an amorphous silica. In this example, the effect of starting feed clay moisture on aggregation is examined. The feed clay, aggregating chemical and process all were identical to that of Example 1, except that the moisture of the feed clay was varied ~L3~ 85 in the range of l to 2% by weight, so that the effective ratios of total water to the amount of silane were in the range of 4.56 to 8.44. The light scatter values of the handsheets prepared using respective aggreS~ated clays, at 10% filler loading, are provided in Table 2. This relationship between moisture and light scatter is graphically illustrated in Figure 7. The effective aggregation can be achieved even at a water to si]ane ratio of 8.44. The preferred range of moisture appears to be between l.0 to 1.75~ by weight of dry clay.
Example 13 The feed clay, aggregating chemical and part of the processing were identical to Example 12, the moisture of the feed clay being 1.08% by weight, except that in the process there was a time delay of lO minutes prior to the repeat lS chemical treatment. The light scatter of a sheet filled with this product at 10% filler loading was 582 cm2/g. Apparently higher residence time is beneficial for developing a more effectively structured aggregate.
Example 14 The starting material was a Feed Clay-I that contained 3% ground calcium carbonate, Carbital-90. The moisture of the feed clay was adjusted to 3.29% by weight. 75 grams o this feed clay was treated with l~ by weight of tetraethoxysilane, (CH3CH2O)4Si, by the usual method of mixing, using a commercial Waring blender. After addition of the silane, mixing was continued for 1.5 minutes. The clay was then subjected to ~3~6~85 vacuum for about two minutes and the whole process was repeated once. The final product was dried at 150C for 15 minutes. The wet void volume of the final product, as determined by RSV method, was 51.2%, an increase of about 11 percentage units over the starting feed clay.
Example 15 In this example, moisture of the Feed Clay~I was adjusted to 2.94% by weight and the clay was treated with 0.5~
by weight of tctraethoxysilane, (CH3CH2o)4si. The rest of the treatment process was identical to that of Example 14. Wet ; void volume of this product was 46.2%, about 6 percentage units higher than the feed clay.
Example 16 The feed clay, feed clay moisture, aggregating chemical and the treatment process all were identical to those described in Example 15, except that the amount of the aggregating agent was 0.25% by weight of the clay. The wet void volume of this product was 47.1%, an increase of about 7 percentage units over the feed clay.
Example 17 This example demonstrates the reIation between the amount of aggregating agent vs. aggregate performance by keep-ing all other conditions the same. The starting material was a Feed Clay-I in which the moisture was adjusted to 0.95% by weight. This feed clay was treated separately using 0.25%, 0.5% and 1.0% by weight of tetraethoxysilane, tCH3CH20)4Si, -22- ~3Q6~
according to the process described in Example 14. The normal-ized light scatter of a sheet filled with these pigments at 10~ f iller loadings and percent wet void volumes of these aggregated fillers are provided in Table 3. Also, the relation between the amount of aggregating agents vs. wet void volume and Light scatter of filled sheets are illustrated in Figures 8 and 9 respectively. It is evident that the silane enhances these properties.
Example 18 This example further demonstrates the relation between the amount of aggregating agent vs. aggregate performance by keeping all other conditions the same. The starting material was a Feed Clay-I where the moisture was adjusted close to 1.72% by weight. This ieed clay was treated separately using 0.25% and 0.5% by weight of tetraethoxysilane, (CH3CH20)4Si according to the process described in Example 17. The normal-ized light scatter of a sheet filled with these pigments at 10~ filler loadings and percent wet void volumes of these aggregated fillers are provided in Table 4.
~ Example 19 This example describes use of an aggregation enhancing agent, calcium chloride. In the process, Feed Clay-I was mixed with 0.5% by weight of dihydrated calcium chloride salt and the feed moisture was adjusted to 1.64~ by weight of the clay. The chemical treatment process was identical to that of Example 17.
1.0% by weight of tetraethoxysilane was used. The normalized -23- ~3~
light scatter of a sheet filled with this pigment at 10% filler loading was 577 cm2/g. The resulting product is more porous as indicated by the substantially higher wet void volume, 61.6%
measured by RSV technique.
Example 20 In this example, the effect of amount of aggregation enhancing agent is examined. The feed clay and the chemical treatment were identical to those described in Example 19, except that in a first set, feed clay was separately dosed with 0.2, 0.5 and 1.0~ by weight of calcium chloride. In each case moisture of the feed clay was adjusted to nearly 1.3~ by weight, after mixing Feed Clay-I with calcium chloride. Similarly, in a second set, feed clay was separately dosed with 0.05 and 0.1% by weight of calcium chloride except that the moisture of the feed clay was adjusted to 1.9% by weight. Each of these clays was treated with 0.5~ by weight of tetraethoxysilane.
The final products are porous aggregates as seen from wet void volume, measured by RSV technique. The wet void volumes are provided in Table 5.
Example 21 Previous examples have demonstrated that the use of tetramethoxysilane produced more efficient aggregates; however, tetraethoxysilane is more cost effective. Thus, ~o produce efficient, but cost effective aggregates, a combination of tetraethoxy- and tetramethoxy- silane was used in this example.
-24- 13~
The feed clay was identical to the one described in Example 14.
The moisture of the feed clay was adjusted to 0.85~ by weight.
The chemical treatment process was essentially identical to the method described in Example 14 except that the composition of the aggregating agents consisted of 0.25~ by weight of tetraet-hoxysilane and 0.05% by weight tetramethoxysilane. The wet void volume of the final product, determined by RSV techniquP, was 51.4%. This is an increase of nearly 11 percentage units over the feed clay. The overall amount of chemical required is sig-nificantly lower than that required for similar aggregation using either tetraethoxy- or tetramethoxy- silane alone.
Example 22 The starting material for this experiment was a commercial coating clay Betagloss. This clay, after initial beneficiation, size cIassification, filtration and redisper-sion was diluted to 40% by weight slurry. This slurry was spray dried and pulverized using a pulverizer produced by Mikropul Corporation. The particle size distribution of this clay was 94% less than 2 micrometer E.S.D. The moisture of this clay was adjusted to 0.86% by weight. 75g. of this clay was treated with 0.25~ by weight of tetraethoxysilane, (CH3CH2O)4Si, using a commercial mixer, a Waring blender. The wet void volume determined by relative sedimentation method - was 57.3~. This is a substantial increase over feed clay wet void volume of 40~.
~3016~5 Example 23 The feed clay, treatm~nt process, aggregating chemical and amount of the tetraethoxysilane were identical to that in Example 22 except that the feed clay was dosed with 0.13 by weight of an aggregation enhancing chemical, calcium chloride, and the moisture of the feed was adjusted to 0.98~ by weight.
The percent wet void volume of the product was S0.4%, an in-crease of about 10 percentage units over the feed clay.
Example 24 Feed Clay-I was equilibrated with moist air to increase moisture of the feed clay from 0.85~ to l.S~ by weight of the clay. This clay was treated with O.S~ by weight of tetraethoxysilane, (CR3CH2o~4si~ under vigorous mixing conditions using a commercial mixer, a Waring blender.
After the treatment with tetraethoxysilane, mixing was con-tinued for an additional l.S minutes. This product was dried at 150C for 15 minutes. Wet void volume of this product was 50.5~ by weight.
Example 25 The feed clay and chemical were identical to that described in Example 24. This time the feed clay was mixed -with 0.5~ by weigh of an aggregation enhancing agent, calcium chloride and the molsture of the feed clay was adjusted to 1.8 by weight of the cIay. 75g. of this clay was treated with 0.5%
by weight of tetraethoxysilane, (CH3C~2O)4Si, in a Waring blender. After the addition of the silane, mixing was continued 13~ 8~ .
for 1.5 minutes. The clay was then subjected to vacuum for about two minutes. The above process with tetraethoxysilane was repeated once. The final product was dried at 150C or 15 minutes. The wet void volume of the final product was 50.1%, about 10 percentage units higher than the feed clay.
Exarnple 26 A series of experiments was conducted using Feed Clay-I as a starting material. The moisture of the feed clay was adjusted to 1.0% by weight. Three separate portions, 75g each, were treated with 0.25% by weight of tetraethoxy-silane, (CH3CH2O)4Si, according to Example 13, except that the time between each chemical treatment was increased to 15, 30 and 60 minutes. The normalized light scatter of handsheets filled with these pigmen~s at 10% loadings is given in Table 6.
In addition, the particle porosity measured as wet void volume is included in Table 6. In each case the light scatter and wet void volume improved significantly from the starting material.
-27- ~3~6~B~
Table 1 Formulations and Coating Formulation Properties _________________________________________________ __ ________ Formulation Control Pigment A* Pigment B**
Components 30 parts 30 parts ___________________________________________________ _________ ~1 Clay 75 parts 60 parts 60 parts Calcium 2S parts 10 parts 10 parts Carbonate Latex 10 parts 10 parts 10 parts Starch 4 parts 4 parts 4 parts Nopcote C-104 0.5 part O.S part 0.5 part Sunrez 700 M 3.12 part 0.12 part 0.12 part Dispex N-40 0.1 part 0.1 part 0.1 part pH 7.6 8.0 8.1 % Solids 64.1 63.9 63.8 Brookfield Viscosity 100 rpm (cps) 880 1080 1040 _____ ____________ _______________________________ _____ _ : *Prepared by using Tetramethoxysilane **Prepared by using Tetraethoxysilane J~
-28- 13~
Table 2 Effect of Feed Clay Moisture on Light Scatter of Handsheets Filled ~Jith - 10~ Chemically Aggregated Kaolinite Pigment ______________________________________________________________ Percent Water/Silane Normalized Light Moisture Moles/Moles Scatter at 10~
Filler Loading ______________________________________________________________ 2.0 8.44 563 1.71 7.22 574 10 1.08 4.56 574 ____________~_____~___________________________________________ Table 3 Effect of Silane Concentration on the Properties of Aggregated Kaolinites Prepared Using Tetraethoxysilane ____________________ ____ ________________ ________________ , Percent Molar Ratio Normalized Percent Chemical of Water to Light Scatter ~et Void Silane at 10~ Filler Volume Loading ___________________ ____________ ____________ _____________ 0.25 21.96 549 47.7 0.5 10.98 551 49.3 l.0 5.48 563 S0.0 _____ __ ____________________ ____ ________________________ -29- ~3~D6~
Table 4 Effect of SiIane Concentration on the Properties of Aggregated Raolinites Prepared _sing Tetraethoxysilane ~: -- -- ______________. ________ ~ 5 Percent Molar Ratio Normalized P~rcent : Chemical of ~ater to Light Scatter Wet Void Silane at 10~ Filler Volume Loading _______ _________ 0.25 39.76 562 ~8.9 0.5 20.10 56~ 50.2 --____________ Table 5 Effect of Calcium Chloride on ~et Void Volu~e of Chemically Aggregated Raolinites Amount of Feed Clay Percent Wet Calcium Chloride Moisture Void Volume*
(% by weight) (% by weight) ______._______________________________________ ____._________ .
0.05 1.9 51.1 0,1 1.9 51.1 0.2 1.3 53.0 0.5 . 1.3 62.5 1.0 1.3 62.9 _____________ ____ ___________________________________________ *The wet void volume of the feed clay was ~0.2.
-30- ~3~
Table 6 . _ _ Effect of Time Delay ~etween Chemical Treatment Steps in the Aggregation of Kaolinlte Usinq 0.?5~ Tetrametho~ysilane.
_____________________________________________________________ Delay Time Normali~ed Light Percent WQt - (Minutes) Scatter at 10~ Void Volume Filler Loading ________ ____________________ _ _____________________________ 542 52.2 546 55.6 544 52.0 ______________________________________________________________ When used in paper coating applications, the structured kaolin pigments of the invention comp~ise from about 5 to 60~ and preferably from about 10 to 30% by weight of the total pigment component of the coating composition. The balance of the pigment can comprise any of the known coating pigments, such as coating grades o~ kaolins, calcium carbonate, titanium dioxide, plastic pigments, etc. The coating ccmpositions, in addition to the pig-ment component, include conventional components, such as an adhe-sive binder, dispersants, and other known additives.
While this invention has been particularly set forth in terms of specifics, it is understood in view of this disclo-sure, that numerous variations upon the invention are now enabled to those skilled in the art, which variations yet reside within the scope of the present teaching. Accordingly, the invention is to be broadly construed, and limited only by the scope and spirit of the claims now appended hereto.
Typically, feed moisture is in the range of 1 to 2~, preferably 1.0 to 1.75% by weight of the feed clay. The most preferred range is 1.5 to 1.75~ by weight of the clay.
The amount of organic silicon compound may range from S 0.1 to 3.0%, preferably from 0.2 to 2.0~ by weight of dry kaolin.
Brief Description of the Drawings In FIGURE 1 are compared the particle size distribu-tion of the starting material and an aggregated product prepared using 1~ tetramethoxysilane.
In FIGURE 2 are plotted the brightness of coated sheets using aggregated pigments and a control consisting of fine clay and calcium carbonate.
In FIGURE 3 are plotted the opacity of coated sheets using aggregated pigments and a control consisting of fine clay and calcium carbonate.
In FIGURE 4 are plotted the paper gloss of coated sheets using aggregated pigments and a control consisting of fine clay and calcium carbonateO
In FIGURE 5 are plotted the print gloss of coated sheets using aggregated pigments and a control consisting of fine clay and calcium carbonate.
In FIGURE 6 are plotted the litho print gloss of coated sheets using aggregated pigments and a control consist-ing of fine clay and calcium carbonate.
In FIGURE 7 is plotted the effect of feed clay moisture on the light scattering characteristic of aggregated -12- ~3~ 85 kaolinite prepared using 1% tetramethoxysilane.
In FIGURE 8 are plotted the percent wet void volume of aggregated pigments vs. amounts of the aggregating agent.
In FIGURE 9 are plotted the light scatter of aggre-gated pigment vs. amounts of aggregating agent.
In the ensuing description, all scattering data are normalized by comparison to the scattering coefficient of samples of the aforementioned Alphatex~. Ideally in a study of the present nature, the same batch of beaten pulp should be used throughout. As this is not practical, the method adopted was to fill one set of sheets in each series of tests using the same Alphatex~ from series to series. Statistically, the Alphatex~ filled samples at 10~ filler had a scattering coeffi-cient of 680 cm2/gram, and in each series in which Alphatex~
differed from 680, the scattering coefficients of the experi-mental samples were accordingly adjusted proportionally to the adjustments which the Alphatex~-containing paper required to bring its value to 680 cm2/gram. This procedure, which was used in subsequent examples, is from time to time referred to in the specification as "normalizingN the scattering coefficients.
Detailed Descri~tion General Methods of PreParation of Feed Cla~
This corresponds to preparation of the commercial product Betagloss~ of the assignee E.C.C. America Inc. (Atlanta, Georgia).
~10~8~
The starting crude material was a blend of crude kao-lins, which were derived from northeast Georgia, and which were comprised of very fine particle size materials. The GE bright-ness of the said crude was in th~e range of 82 to 37. In all instances in this specification it will be understood that brightness values are obtained according to the standard specifi-cation established by TAPPI procedure T-646 os-75.
The crude clays were beneficiated according to the gen-eral practice used in kaolinite processing industries. The bene-ficiated clays were classified by centrifugation to 94% less than2 micrometer E.S.D. (equivalent spherical diameter). The classi-fied clays were flocculatsd using 0.25~ by weight of aluminum sulfate and adjusting the pH to 3.5 with sulfuric acid. The flocculated kaolinites were filtered. The significantly dried (about 20% moisture remains) kaolinites were redispersed with 0.25~ by weight of sodium polyacrylate and the pH adjusted to about 7Ø The redispersed kaolinite was spray dried.
This method of preparing fsed clays is general and may be varied, particularly if so pointed out in specific Examples; the main variations are differences in particle si~e distribution and the addition of calcium carbonate.
Standard Method of Relative Sedimentation Volume Measurement The relative sedimentation volume of treated and start-ing material was measured to determine the exten~ and nature of aggregation. In the procedure, a nearly 55% solids slurry of pigment was prepared that contained 0.3 milliliter of sodium 31~
polyacrylate. This slurry was then spun at 7000 rpm for 45 min-utes. The sediment volume was calculated using dry weight of clay, wet weight of clay, and calculating volume of clay using density of dry clay of 2.6g/ml.
The invention is demonstrated in the following examples which are intended to be illustrative but not limitative.
Example 1 The starting feed clay was prepared from a blend of two fine Northeastern crude clays from Georgia. The crude clays were refined by common commercial beneficiation methods. The refined clay was classified to 96~ less than 2 micrometer E.S.D.
The classified clay was blended with ground calcium carbonate JS
(Carbital -90) at 3% weight of dry kaolinite. The blend was spray dried and pulverized using a pulverizer manufactured by Mikropul Corporation. This clay will be referred to as Feed Clay-I.
75 9. of substantially dry powder, moisture 0.85~, of Feed Clay-I was treated with 1% by weight of tetramethoxy-silane, supplied by Petrarch Chemical Co., with vigorous mixing in a Waring blender. Once the mixing of powder with liquid was completed, the clay was allowed to mix for an additional 1.5 minutes. Excess silane and resultant methanol as a by-product were removed by subjecting the clay to vacuum (nearly 30 torr). The above process with tetramethoxysilane was repeated once and the final product was allowed to dry at 150C for fifteen minutes.
~n~
The particle size distributions of the starting Feed Clay-I and the final product are illustrated in Fig. 1. The particle size distribution indicates formation of a structured aggregate with very narrow particle size distribution.
Handsheets were prepared using the above aggregated clay from bleached sulfite pulp. The sheets were filled at three filler loadings. The reflectivity of the handsheets was measured and converted to light scatter according to a modified Kabulka-Munk equation. The normalized light scatter of sheets filled at 10% filler loading with this product was 578 cm2/g.
This is a gain of 60 scatter units from untreated Feed Clay-I.
The intraparticle porosity of the pigment, given as percent wet void volume and determined by the relative sedimentation method (RSV) was 57.3%. This is an increase of about 17 percentage units from the feed clay. The increase in wet void volume indicates the formation of aggregate structure and development of the permanent porosity.
Example 2 The process and the chemical used were essentially identical to Example 1, except that the feed was a fine commercial clay, Betagloss. The particle size distribution and moisture of this feed clay were 94% less than 2 micro-meter, and 0.85% respectively. The normalized light scatter of a sheet filled with the final aggregated product, at 10%
filler loading, was 562 cm2/g. Wet void volume of the product determined by RSV was 56.4%, an increase of about 16~ percentage units over the feed clay.
-16- ~3~6~8~ -Example 3 The feed clay, aggreclating agent and the mixing process were essentially identical to that of Example 2, except that the clay was treated with 0.45~ by weight of ammonia gas following each evacuation step. The normalized light scatter of a sheet filled with this pigment, at 10% filler loading, was 550 cm2/g.
The wet void volume of the product, determined by RSV, was 56.7~. Wet void volume and scatter respectively are about 16 percentage units and 30 scatter units higher than the feed clay.
Example 4 In this example Feed Clay-II was prepared by mixing 3% ground calcium carbonate with previously spray dried and pulverized ~etagloss followed by drying at 150C for 15 minutes. The moisture of this feed clay-II was 0.6~% by weight.
The aggregating chsmical and the treatment process were essentially identical to Example 1. The normalized light scatter of a sheet filled with this pigment at 10~ filler loading was 585 cm2/g, which is an increase of about 65 units over the ~eed clay. Wet void volume is about 16 percentage units higher than the feed clay, thus 55.9~.
Example 5 ~eed Clay-II was treated by the es~entially identical method and chemicals described in Example 3. The normalized light scatter o~ a sheet filled with this pigment at 10~ filler loading was 5~ cm2/g. There was an about 16.1 percentage units increase in wet void volume over the feed clay following the chemical aggregation, thus 56.1~.
6~5 Exa_ple 6 The feed clay and the process of treatment were essentially identical to the method described in Example 2, except that the aggregating agent was an organo-silicon compound containing ethoxy groups. (CH3CH2O)4Si. The normal-ized light scatter of a sheet filled with this pigment at 10 filler loading was 547 cm2/g. The wet void volume of the product by RSV was 54.1%. Upon chemical aggregation, wet void volume and light scatter increased by about 14 percentage units and 27 scatter units respectively over the feed clay.
Example 7 The feed clay, aggregating agent, and the treatment process all were essentially identical to the method described in Example 6 except that the clay was exposed to 0.4S~ by weight of ammonia immediately following the evacuation step as described~
in Example 3. The normalized light scatter o a sheet filled with this pigment at 10% filler loading was 544 cm?/g. The wet void volume determined by RSV of the product was 54.9%.
Example 8 The feed clay and process were essentially identical to the method described in Example 4 except that the aggre~
gating chemical was tetraethoxysilane, (C~3CH2O)4Si. The normal-ized light scatter of a sheet filled with this pigment at 10~
filler loading was 570 cm2/g. The relative sedimentation method showed the product to have 52.1 percent wet void volume. The increases in llght scatter and wet void volume amount to 50 : ~ ~
~3~ 85 scatter units and about 12 percentage units over the feed clay, respectively.
Exc~m~le 9 The process and aggregating chemical were essentially S identical to the method described in Example 7 except that Feed Clay-II was the starting material. The normalized light scatter of a sheet filled with this structured aggregated clay, at 10%
filler loading, was 584 cm2/g. In addition, the wet void volume determined by RSV was 54.4~, an increase of about 14 percentage units over the feed clay.
Example 10 The process, aggregating chemical and the feed clay all were essentially identical to the method described in Example 1, except that the moisture content of the feed clay was such that the molar ratio of water to silane was 9.69, which is equivalent to a moisture content of the feed clay of about 1.11~ by weight. The relative sedimentation method showed the product to have 57.5 percent wet void volume.
This product was used to determine coated sheet properties of light weight coated offset grade paper. In the coating formulationj 30 parts of regular coating pigment were replaced with this product. The typical formulation and rele-vant formulation properties are provided in Table 1.
Almost all of the coated sheet properties improved by application of this aggregated clay, for example, sheet gloss, print gloss and opacity. These coated sheet properties are ~1 30~Z 35 .
illustrated in Figures 2 through 6. The properties, i.e.
brightness, opacity, gloss, print gloss, and litho print gloss are compared with a common offset control formulation.
Exan!ple 11 The feed clay and the process were essentially identical to the method described in Example 10, except that the aggregating chemical was (CH3C~2O)4Si, tetraetho~ysilane.
The relative sedimentation method showed the product to have 51.9 percent wet void volume, an improvement of nearly 12 percentage units over untreated feed clay.
As in Example 10, this pigment was evaluated in a paper coating application. Once again, significent improvement of coated sheet properties is observed with this aggregated structure pigment. The essential coated sheet properties, e.g.
brightness, opacity, gloss, print gloss, and litho print gloss are illustrated in Figures 2 to 6.
Example 12 It is postulated that the hydrolysis, and subsequent polymerization of the hydrolyzed products, of the orsano-silicon compound, e.g. silane, would depend on the availability of free moisture. In the presence of excessive moisture it might be possible that the hydrolyzed product would precipitate as an amorphous silica. In this example, the effect of starting feed clay moisture on aggregation is examined. The feed clay, aggregating chemical and process all were identical to that of Example 1, except that the moisture of the feed clay was varied ~L3~ 85 in the range of l to 2% by weight, so that the effective ratios of total water to the amount of silane were in the range of 4.56 to 8.44. The light scatter values of the handsheets prepared using respective aggreS~ated clays, at 10% filler loading, are provided in Table 2. This relationship between moisture and light scatter is graphically illustrated in Figure 7. The effective aggregation can be achieved even at a water to si]ane ratio of 8.44. The preferred range of moisture appears to be between l.0 to 1.75~ by weight of dry clay.
Example 13 The feed clay, aggregating chemical and part of the processing were identical to Example 12, the moisture of the feed clay being 1.08% by weight, except that in the process there was a time delay of lO minutes prior to the repeat lS chemical treatment. The light scatter of a sheet filled with this product at 10% filler loading was 582 cm2/g. Apparently higher residence time is beneficial for developing a more effectively structured aggregate.
Example 14 The starting material was a Feed Clay-I that contained 3% ground calcium carbonate, Carbital-90. The moisture of the feed clay was adjusted to 3.29% by weight. 75 grams o this feed clay was treated with l~ by weight of tetraethoxysilane, (CH3CH2O)4Si, by the usual method of mixing, using a commercial Waring blender. After addition of the silane, mixing was continued for 1.5 minutes. The clay was then subjected to ~3~6~85 vacuum for about two minutes and the whole process was repeated once. The final product was dried at 150C for 15 minutes. The wet void volume of the final product, as determined by RSV method, was 51.2%, an increase of about 11 percentage units over the starting feed clay.
Example 15 In this example, moisture of the Feed Clay~I was adjusted to 2.94% by weight and the clay was treated with 0.5~
by weight of tctraethoxysilane, (CH3CH2o)4si. The rest of the treatment process was identical to that of Example 14. Wet ; void volume of this product was 46.2%, about 6 percentage units higher than the feed clay.
Example 16 The feed clay, feed clay moisture, aggregating chemical and the treatment process all were identical to those described in Example 15, except that the amount of the aggregating agent was 0.25% by weight of the clay. The wet void volume of this product was 47.1%, an increase of about 7 percentage units over the feed clay.
Example 17 This example demonstrates the reIation between the amount of aggregating agent vs. aggregate performance by keep-ing all other conditions the same. The starting material was a Feed Clay-I in which the moisture was adjusted to 0.95% by weight. This feed clay was treated separately using 0.25%, 0.5% and 1.0% by weight of tetraethoxysilane, tCH3CH20)4Si, -22- ~3Q6~
according to the process described in Example 14. The normal-ized light scatter of a sheet filled with these pigments at 10~ f iller loadings and percent wet void volumes of these aggregated fillers are provided in Table 3. Also, the relation between the amount of aggregating agents vs. wet void volume and Light scatter of filled sheets are illustrated in Figures 8 and 9 respectively. It is evident that the silane enhances these properties.
Example 18 This example further demonstrates the relation between the amount of aggregating agent vs. aggregate performance by keeping all other conditions the same. The starting material was a Feed Clay-I where the moisture was adjusted close to 1.72% by weight. This ieed clay was treated separately using 0.25% and 0.5% by weight of tetraethoxysilane, (CH3CH20)4Si according to the process described in Example 17. The normal-ized light scatter of a sheet filled with these pigments at 10~ filler loadings and percent wet void volumes of these aggregated fillers are provided in Table 4.
~ Example 19 This example describes use of an aggregation enhancing agent, calcium chloride. In the process, Feed Clay-I was mixed with 0.5% by weight of dihydrated calcium chloride salt and the feed moisture was adjusted to 1.64~ by weight of the clay. The chemical treatment process was identical to that of Example 17.
1.0% by weight of tetraethoxysilane was used. The normalized -23- ~3~
light scatter of a sheet filled with this pigment at 10% filler loading was 577 cm2/g. The resulting product is more porous as indicated by the substantially higher wet void volume, 61.6%
measured by RSV technique.
Example 20 In this example, the effect of amount of aggregation enhancing agent is examined. The feed clay and the chemical treatment were identical to those described in Example 19, except that in a first set, feed clay was separately dosed with 0.2, 0.5 and 1.0~ by weight of calcium chloride. In each case moisture of the feed clay was adjusted to nearly 1.3~ by weight, after mixing Feed Clay-I with calcium chloride. Similarly, in a second set, feed clay was separately dosed with 0.05 and 0.1% by weight of calcium chloride except that the moisture of the feed clay was adjusted to 1.9% by weight. Each of these clays was treated with 0.5~ by weight of tetraethoxysilane.
The final products are porous aggregates as seen from wet void volume, measured by RSV technique. The wet void volumes are provided in Table 5.
Example 21 Previous examples have demonstrated that the use of tetramethoxysilane produced more efficient aggregates; however, tetraethoxysilane is more cost effective. Thus, ~o produce efficient, but cost effective aggregates, a combination of tetraethoxy- and tetramethoxy- silane was used in this example.
-24- 13~
The feed clay was identical to the one described in Example 14.
The moisture of the feed clay was adjusted to 0.85~ by weight.
The chemical treatment process was essentially identical to the method described in Example 14 except that the composition of the aggregating agents consisted of 0.25~ by weight of tetraet-hoxysilane and 0.05% by weight tetramethoxysilane. The wet void volume of the final product, determined by RSV techniquP, was 51.4%. This is an increase of nearly 11 percentage units over the feed clay. The overall amount of chemical required is sig-nificantly lower than that required for similar aggregation using either tetraethoxy- or tetramethoxy- silane alone.
Example 22 The starting material for this experiment was a commercial coating clay Betagloss. This clay, after initial beneficiation, size cIassification, filtration and redisper-sion was diluted to 40% by weight slurry. This slurry was spray dried and pulverized using a pulverizer produced by Mikropul Corporation. The particle size distribution of this clay was 94% less than 2 micrometer E.S.D. The moisture of this clay was adjusted to 0.86% by weight. 75g. of this clay was treated with 0.25~ by weight of tetraethoxysilane, (CH3CH2O)4Si, using a commercial mixer, a Waring blender. The wet void volume determined by relative sedimentation method - was 57.3~. This is a substantial increase over feed clay wet void volume of 40~.
~3016~5 Example 23 The feed clay, treatm~nt process, aggregating chemical and amount of the tetraethoxysilane were identical to that in Example 22 except that the feed clay was dosed with 0.13 by weight of an aggregation enhancing chemical, calcium chloride, and the moisture of the feed was adjusted to 0.98~ by weight.
The percent wet void volume of the product was S0.4%, an in-crease of about 10 percentage units over the feed clay.
Example 24 Feed Clay-I was equilibrated with moist air to increase moisture of the feed clay from 0.85~ to l.S~ by weight of the clay. This clay was treated with O.S~ by weight of tetraethoxysilane, (CR3CH2o~4si~ under vigorous mixing conditions using a commercial mixer, a Waring blender.
After the treatment with tetraethoxysilane, mixing was con-tinued for an additional l.S minutes. This product was dried at 150C for 15 minutes. Wet void volume of this product was 50.5~ by weight.
Example 25 The feed clay and chemical were identical to that described in Example 24. This time the feed clay was mixed -with 0.5~ by weigh of an aggregation enhancing agent, calcium chloride and the molsture of the feed clay was adjusted to 1.8 by weight of the cIay. 75g. of this clay was treated with 0.5%
by weight of tetraethoxysilane, (CH3C~2O)4Si, in a Waring blender. After the addition of the silane, mixing was continued 13~ 8~ .
for 1.5 minutes. The clay was then subjected to vacuum for about two minutes. The above process with tetraethoxysilane was repeated once. The final product was dried at 150C or 15 minutes. The wet void volume of the final product was 50.1%, about 10 percentage units higher than the feed clay.
Exarnple 26 A series of experiments was conducted using Feed Clay-I as a starting material. The moisture of the feed clay was adjusted to 1.0% by weight. Three separate portions, 75g each, were treated with 0.25% by weight of tetraethoxy-silane, (CH3CH2O)4Si, according to Example 13, except that the time between each chemical treatment was increased to 15, 30 and 60 minutes. The normalized light scatter of handsheets filled with these pigmen~s at 10% loadings is given in Table 6.
In addition, the particle porosity measured as wet void volume is included in Table 6. In each case the light scatter and wet void volume improved significantly from the starting material.
-27- ~3~6~B~
Table 1 Formulations and Coating Formulation Properties _________________________________________________ __ ________ Formulation Control Pigment A* Pigment B**
Components 30 parts 30 parts ___________________________________________________ _________ ~1 Clay 75 parts 60 parts 60 parts Calcium 2S parts 10 parts 10 parts Carbonate Latex 10 parts 10 parts 10 parts Starch 4 parts 4 parts 4 parts Nopcote C-104 0.5 part O.S part 0.5 part Sunrez 700 M 3.12 part 0.12 part 0.12 part Dispex N-40 0.1 part 0.1 part 0.1 part pH 7.6 8.0 8.1 % Solids 64.1 63.9 63.8 Brookfield Viscosity 100 rpm (cps) 880 1080 1040 _____ ____________ _______________________________ _____ _ : *Prepared by using Tetramethoxysilane **Prepared by using Tetraethoxysilane J~
-28- 13~
Table 2 Effect of Feed Clay Moisture on Light Scatter of Handsheets Filled ~Jith - 10~ Chemically Aggregated Kaolinite Pigment ______________________________________________________________ Percent Water/Silane Normalized Light Moisture Moles/Moles Scatter at 10~
Filler Loading ______________________________________________________________ 2.0 8.44 563 1.71 7.22 574 10 1.08 4.56 574 ____________~_____~___________________________________________ Table 3 Effect of Silane Concentration on the Properties of Aggregated Kaolinites Prepared Using Tetraethoxysilane ____________________ ____ ________________ ________________ , Percent Molar Ratio Normalized Percent Chemical of Water to Light Scatter ~et Void Silane at 10~ Filler Volume Loading ___________________ ____________ ____________ _____________ 0.25 21.96 549 47.7 0.5 10.98 551 49.3 l.0 5.48 563 S0.0 _____ __ ____________________ ____ ________________________ -29- ~3~D6~
Table 4 Effect of SiIane Concentration on the Properties of Aggregated Raolinites Prepared _sing Tetraethoxysilane ~: -- -- ______________. ________ ~ 5 Percent Molar Ratio Normalized P~rcent : Chemical of ~ater to Light Scatter Wet Void Silane at 10~ Filler Volume Loading _______ _________ 0.25 39.76 562 ~8.9 0.5 20.10 56~ 50.2 --____________ Table 5 Effect of Calcium Chloride on ~et Void Volu~e of Chemically Aggregated Raolinites Amount of Feed Clay Percent Wet Calcium Chloride Moisture Void Volume*
(% by weight) (% by weight) ______._______________________________________ ____._________ .
0.05 1.9 51.1 0,1 1.9 51.1 0.2 1.3 53.0 0.5 . 1.3 62.5 1.0 1.3 62.9 _____________ ____ ___________________________________________ *The wet void volume of the feed clay was ~0.2.
-30- ~3~
Table 6 . _ _ Effect of Time Delay ~etween Chemical Treatment Steps in the Aggregation of Kaolinlte Usinq 0.?5~ Tetrametho~ysilane.
_____________________________________________________________ Delay Time Normali~ed Light Percent WQt - (Minutes) Scatter at 10~ Void Volume Filler Loading ________ ____________________ _ _____________________________ 542 52.2 546 55.6 544 52.0 ______________________________________________________________ When used in paper coating applications, the structured kaolin pigments of the invention comp~ise from about 5 to 60~ and preferably from about 10 to 30% by weight of the total pigment component of the coating composition. The balance of the pigment can comprise any of the known coating pigments, such as coating grades o~ kaolins, calcium carbonate, titanium dioxide, plastic pigments, etc. The coating ccmpositions, in addition to the pig-ment component, include conventional components, such as an adhe-sive binder, dispersants, and other known additives.
While this invention has been particularly set forth in terms of specifics, it is understood in view of this disclo-sure, that numerous variations upon the invention are now enabled to those skilled in the art, which variations yet reside within the scope of the present teaching. Accordingly, the invention is to be broadly construed, and limited only by the scope and spirit of the claims now appended hereto.
Claims (29)
1. A method for producing a kaolin pigment providing enhanced optical and printability properties when used in paper manufacture, which comprises mixing kaolin particles with an aggregating agent comprising an organic silicon compound selected from the group consisting of symmetric compounds hav-ing the formula here R=CH3, C2H5, C3H7, n-C4H9, sec-C4H9 and C6H5 and asymmetric compounds having the formula where R=C2H5, X=Cl or Br, and R?=H, and recovering an aggregated particulate kaolin pigment product.
2. The method according to claim 1 in which the kaolin is substantially dry.
3. The method according to claim 1 in which the feed kaolin moisture content is in the range of 1 to 2% by weight.
4. The method according to claim 3 in which the feed moisture content is in the range of 1.0 to 1.75% by weight.
5. The method according to claim 3 in which the feed moisture content is in the range of 1.5 to 1.75% by weight.
6. The method according to claim 1 in which the organic silicon compound comprises four hydrolyzable groups linked to silicon.
7. The method according to claim 1 in which the organic silicon compound is hydrolyzable to give liquid by-products.
8. The method according to claim 1 in which the organic silicon compound is a silane having the formula (RO)4Si in which R is an alkyl group.
9. The method according to claim 8 in which R is an alkyl group of 1 to 4 carbon atoms and the R groups in the silane can be the same or different.
10. The method according to claim 9 in which the silane is selected from the group consisting of tetramethoxy-silane and tetraethoxysilane and mixtures thereof.
11. The method according to claim 1 in which the kaolin particles are additionally mixed with an aggregation enhancing agent selected from the group consisting of alkaline earth metal salts and lithium chloride.
12. The method according to claim 11 in which the aggregation enhancing agent comprises a soluble salt of an alkaline earth metal ion.
13. The method according to claim 12 in which the aggregation enhancing agent comprises calcium chloride.
14. The method according to claim 1 in which the treatment with the organic silicon compound is repeated.
15. The method according to claim 1 in which the product is dried to shorten the time required for aggregation.
16. The method according to claim 1 in which the amount of the organic silicon compound is in the range of 0.1 to 3.0% by weight of the kaolin on a dry basis.
17. The method according to claim 16 in which the amount of the organic silicon compound is in the range of 0.2 to 2.0% by weight of the kaolin on a dry basis.
18. The method according to claim 11 in which the amount of the aggregation enhancing agent is in the range of 0.05% to 3.0% by weight of the kaolin on a dry basis.
19. The method according to claim 1 in which the treated kaolin is further treated by being exposed to ammonia.
20. The method according to claim 1 in which the feed kaolin comprises an air classified fine kaolin in which 80%
of the particles are finer than 2 micrometers E.S.D.
of the particles are finer than 2 micrometers E.S.D.
21. The method according to claim 1 in which 96%
of the feed kaolin particles are finer than 2 micrometers E.S.D.
of the feed kaolin particles are finer than 2 micrometers E.S.D.
22. The method according to claim 1 in which the kaolin particles are mixed with calcium carbonate.
23. The method according to claim 1 in which the feed kaolin moisture content is such that the molar ratio of water to aggregating agent is in the range of 2 to 50.
24. The method according to claim 23 in which the range is 4 to 20.
25. A method of coating paper to improve optical and printability properties of the coated paper which comprises employing a pigment comprising kaolin particles that have been mixed with an organic silicon compound selected from the group consisting of symmetric compounds having the formula where R=CH3, C2H5, C3H7, n-C4H9, sec-C4H9 and C6H5 and asymmetric compounds having the formula where R=C2H5, X=Cl or Br, and R1=H.
26. A method of incorporating a filler in paper to improve light scattering and opacifying properties which comprises employing a pigment comprising kaolin particles that have been mixed with an organic silicon compound selected from the group consisting of symmetric compounds having the formula where R=CH3, C2H5, C3H7, n-C4H9, sec-C4H9 and C6H5 and asymmetric compounds having the formula where R=C2H5, X=Cl or Br, and R1=H.
27. The method according to claim 25 or 26 in which the organic silicon compound is selected from the group consist-ing of tetramethoxysilane and tetraethoxysilane and mixtures thereof.
28. A pigment useful in paper coating and as a filler for paper which comprises kaolin particles that have been mixed with an organic silicon compound selected from the group consist-ing of symmetric compounds having the formula where R=CH3, C2H5, C3H7, n-C4H9, sec-C4H9 and C6H5 and asymmetric compounds having the formula where R=C2H5, X=Cl or Br, and R1=H.
29. A pigment according to claim 28 in which the organic silicon compound has the formula (RO)4Si in which R is an alkyl group of 1 to 4 carbon atoms and the R groups may be the same or different.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000581316A CA1306085C (en) | 1988-10-26 | 1988-10-26 | Kaolinite aggregation using organo-silicon compounds |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000581316A CA1306085C (en) | 1988-10-26 | 1988-10-26 | Kaolinite aggregation using organo-silicon compounds |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1306085C true CA1306085C (en) | 1992-08-11 |
Family
ID=4138979
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000581316A Expired - Fee Related CA1306085C (en) | 1988-10-26 | 1988-10-26 | Kaolinite aggregation using organo-silicon compounds |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1306085C (en) |
-
1988
- 1988-10-26 CA CA000581316A patent/CA1306085C/en not_active Expired - Fee Related
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