CA2020207C - Bonded paper pigments - Google Patents
Bonded paper pigmentsInfo
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- CA2020207C CA2020207C CA 2020207 CA2020207A CA2020207C CA 2020207 C CA2020207 C CA 2020207C CA 2020207 CA2020207 CA 2020207 CA 2020207 A CA2020207 A CA 2020207A CA 2020207 C CA2020207 C CA 2020207C
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- polyacrylamide polymer
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/34—Silicon-containing compounds
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- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
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- Paper (AREA)
Abstract
This invention pertains to novel bonded pigments used in paper products. A novel composition useful in removing undesirable pitch from the papermaking process and papermaking equipment and fixing the pitch into the paper, whilst simulta-neously improving the optical, physical and printability properties of newsprint and groundwood specialties comprising:
(a) a precipitated sodium aluminosilicate having a primary particle size in the range of about 10 to 60 nanometers, and secondary agglomerations of about 1 to 50 microns; and (b) a high molecular weight cationic polyacrylamide polymer having a molecular weight of about 100,000 to about 50,000,000.
(a) a precipitated sodium aluminosilicate having a primary particle size in the range of about 10 to 60 nanometers, and secondary agglomerations of about 1 to 50 microns; and (b) a high molecular weight cationic polyacrylamide polymer having a molecular weight of about 100,000 to about 50,000,000.
Description
NOVEL BONDED PAPER PIGNENTS
FIELD OF THE INVENTION
This invention pertains to novel bonded white paper pigments used in paper products. More particularly, this invention relates to novel combinations of precipitated sodium aluminosilicate and cationic polyacrylamide polymer which together provide superior brightness, friction qualities and printability to newsprint and ground wood specialties, while at the same time decreasing pitch deposition on papermaking equipment.
BACKGROUND OF THE INVENTION
Precipitated silicas and silicates have been used for many years as auxiliaries in rubber and plastics, as feedstuff additives and as fillers for paper products. One family of silicates is manufactured by reacting sodium silicate (water glass) with aluminum sulphate and sulphuric acid to precipitate a sodium aluminosilicate.
Silicas and silicates are obtainable in the marketplace from corporations such as Tokuyama Soda Co. Ltd., Japan, J.M.
Huber Corporation, U.S.A., Degussa, West Germany, Akzo Chemicals Inc., West Germany and Rhône Poulenc, France. In Japan, precipitated silicas and silcates are widely used in paper products, including newsprint, to improve print quality and to reduce paper "snaking" in the pressroom.
In North America, there is a strong growing trend to include pigments in newsprint in order to produce a higher quality newspaper. For instance, in the United States, the newspaper, U.S.A. Today, which is computer type-set and trans-mitted by telecommunication to various paper publishing houses throughout the United States, has set high standard specifica-tions for the newsprint that is used in publishing its daily 1 - `.L
newspaper. The newsprint must be of a specified level of bright-ness, opacity, smoothness, and have minimum colour bleed-through. The specifications for the U.S.A. Today newsprint are sufficiently high that most newsprint paper mills in North America cannot meet the specifications without inclusion of some kind of pigment in the paper.
In the manufacture of newsprint and groundwood specialties, it is important to retain as many of the valuable cellulose fibers as possible. Lost fibres increase the overall manufacturing cost of the newsprint. Retention aids have been developed for the purpose of retaining fibres in newsprint.
These retention aids are usually polymeric materials which flocculate the cellulose fibres together, thereby minimizing fibre loss. Polymers used as retention aids include polyacryl-amides, polyethyleneimines, polyethyleneoxide and modified starch.
To date, it has been difficult to be able to use precipitated sodium aluminosilicate, in conjunction with all retention aids in the manufacture of newsprint without incurring certain disadvantages. Certain retention aids tend to agglomer-ate the sodium aluminosilicate particles into groups, thereby negating an even distribution of the sodium aluminosilicate particles throughout the newsprint fibres. To offset this phenomenon, a higher volume of sodium aluminosilicate must be added to the newsprint, which increases cost and tends to adversely decrease the quality of the treated newsprint.
Moreover, retention aids which tie together sodium aluminosili-cate particles will be less effective at performing their secondfunction, that is, retaining cellulose fibres together.
The performance of retention aids can also be detri-mentally affected by the presence of wood resin in the furnish.
In this discussion, wood resin present in wood and wood pulps is used to denote a complex agglomeration of organic materials such as terpenes, fatty acids, resin acids, esters and unsaponi-fiables. These wood resins are water insoluble components whichare present on the surfaces of fibres and in the form of colloidal droplets in the papermaking process water. In addition to interfering with the performance of retention aids, the wood resin may accumulate thus leading to pitch deposition on the surfaces of the process equipment. In the past, the most common chemical methods for controlling pitch deposition have included the use of talc, dispersants, alum and sodium aluminate.
The invention is directed to novel compositions useful in minimizing pitch deposition and removing pitch from paper-making equipment whilst improving the brightness, friction and 15printability qualities of cellulose paper comprising: (a) a precipitated sodium aluminosilicate having a primary particle in the range of about 10 to 60 nanometers which are agglomerated into particles in the size range of about 1 to 50 microns; and (b) a high molecular weight cationic polyacrylamide polymer 20having a molecular weight of about lOO,oOO to about 50,000,000.
The high molecular weight cationic charge poly-acrylamide polymer may be of a molecular chain length suffi-ciently long that-it does not have the effect of coagulating the sodium aluminosilicate particles together when the composition is added to newsprint pulp suspension.
The invention in a specific aspect is directed to a composition useful in reducing the accumulation of pitch on paper processing equipment and improving the brightness qualities of cellulose paper comprising: (a) a precipitated sodium alumino-silicate having a primary particle size in the range of about 25 to about 35 nanometers, and secondary agglomerations of about 3 to 5 microns; and (b) a high molecular weight cationic poly-acrylamide polymer having an average molecular weight in therange of about 5,000,000 to 12,000,000.
-The cationic charge in the polyacrylamide polymer can be based on acrylamide plus a substance selected from the group consisting of cationic quaternary ammonium monomers, dimethylaminoethyl acrylate, dimethyl sulfate quaternary;
dimethylaminoethyl acrylate, methyl chloride quaternary; and 2-hydroxy-n-propyldimethylamino acrylate, methyl chloride quater-nary. The charge density of the polyacrylamide polymer may be less than about 30 mole percent or may less than about 12 mole percent.
The secondary agglomerations of the sodium alumino-silicate may have a size range wherein about 5% of the particles have diameters greater than about 10 to 15 microns, about 50% of the particles have diameters greater than about 3 to 5 microns, and about 95% of the particles have diameters greater than about 2 to 3 microns.
The sodium aluminosilicate may have the following physical properties:
Brightness Q 460nm - 98 Crystal Structure - Amorphous Primary Particle Size nm - 25 - 35 Average Particle size, ~m - 3 - 5 BET Surface Area m2/g - 80 - 100 Tamped Density g/litre - 170 - 210 Oil Absorption cc/100 g - 180 - 200 The invention is also directed to a method of reducing the accumulation of pitch on paper processing equipment which comprises adding to paper furnish supplied to the paper process-ing equipment a composition comprising: (a) a precipitated sodium aluminosilicate having a primary particle size in the range of about 10 to 60 nanometers, and secondary agglomerations of about 1 to 50 microns; and (b) a high molecular weight cationic polyacrylamide polymer having an average molecular weight in the range of about 100,000 to about 50,000,000.
DRAWINGS
In drawings which depict specific embodiments of the invention, but which should not be construed as restricting the spirit or scope of the invention in any way:
Figure 1 illustrates increases in slip angle obtained in a mill evaluation for newsprint treated with DIACHEM WHITE
CARBON(TM) and polyacrylamide polymer.
Figure 2 illustratés the reduction in colloidal pitch and increase in percent dichloromethane extractables during the same period of the mill evaluation as illustrated in Figure 1.
Figure 3 illustrates a plot of slip angle versus percent filler product of handsheets filled with two types of sodium aluminosilicate product, both treated with polyacrylamide polymer;
Figure 4 illustrates a scanning electronmicrograph of a cellulose fiber mat treated with DIACHEM WHITE CARBON, the reference line representing five microns;
Figure 5 illustrates a molecular mapping of silica atoms distributed in newsprint treated with a DIACHEM WHITE
CARBON polyacrylamide mixture according to the invention;
Figure 6 illustrates a transmission electronmicrograph of newsprint treated with a DIACHEM WHITE CARBON polyacrylamide mixture according to the invention, the reference line represent-ing five microns; and Figure 7 illustrates a scanning electronmic~oy~aph of the edge of a paper sheet treated with the DIACHEM WHITE CARBON
polyacrylamide mixture according to the invention as illustrated in Figure 6.
2~20207 -DETAILED DESCRIPTION OF SPECIFIC
EMBODIMENTS OF THE INVENTION
The inventors have discovered that a mixture of sodium aluminosilicate (DIACHEM WHITE CARBON) of certain specifications, in conjunction with a high molecular weight cationic polyacryl-amide polymer is advantageous in treating cellulose pulp suspension during the manufacture of paper such as newsprint to obtain a high quality filled paper, including newsprint.
Specifically, this invention is applicable to furnishes based on mech~n;cal pulp and in part semi-bleached kraft pulp, unbleached kraft pulp, and/or unbleached sulfite pulp. Advantages of treatment include reduced pitch deposition on the paper machine, and because of even distribution of white carbon throughout the cellulose fibre mat, increased brightness, enhanced friction qualities and reduced print through in offset and letterpress printing, are obtained.
The precipitated sodium aluminosilicate component of the invention (DIACHEM WHITE CARBON(TM)) should preferably have a chemical composition approximating the chemical composition depicted in Table 1 below:
Table 1 DIACHEM WHITE CARBON Sodium Aluminosilicate Chemical ComPosition sio2 - 71.0%
Al2O3 - 8.0%
CaO - 0.2%
Na2O - 7.0%
H2O - 5.0%
LOI (incl. H20) - 13.0%
Impurities (Fe, other heavy metals) less than 0.05%
The precipitated silicate product used in the inven-tion, described with the trade-mark DIACHEM WHITE CARBONtTM), should have physical properties approximating those depicted in Table 2 below:
Table 2 DIACHEM WHITE CARBON
Physical Properties Brightness Q 46Onm - 98 Crystal Structure - Amorphous Primary Particle Size nm - 25 - 35 Average Particle size, ~m - 3 - 5 BET Surface Area m2/g - 80 - 100 Tamped Density g/litre - 170 - 210 Oil Absorption cc/100 g - 180 - 200 Valley Abrasion #, mg wire loss - 4 - 10 The DIACHEM WHITE CARBON(TM) product used in the invention should have particle diameters of 1-50 ~m, with particles of over 45 ~m (325 mesh sieve residue) at a ratio of under 0.4%, or ideally under 0.1%. The particle size distribu-tion, measured by the Coulter Counter method with a 100 ~m capillary, should be such that 5% of the particles have diameters greater than 10-15 ~m, 50% have diameters greater than 3-5 ~m, and 95% have diameters greater than 2-3 ~m. The "cauliflower-like" sodium aluminosilicate particles are comprised of agglomer-ations of smaller primary particles which are preferably in the range of 25-35 ~m. The distinct morphology of the secondary agglomerations have been shown to have a number of important advantages as discussed below:
1. A high surface area which increases fiber-pigment-air interfaces for improved scattering of incident light and thereby alters the optical properties of newsprint sheet.
In mill trials, brightness increases of 1.2 - 1.7 points per one -percent retained DIACHEM WHITE CARBON have been achieved with no adverse effect on printing opacity.
2. A high void volume, as indicated by the oil absorption value, combined with a high surface area, provides to the furnish sites for the effective binding of pitch and the wood resin precursor. With subsequent retention of the pitch-containing DIACHEM WHITE CARBON particles in the paper through the use of the polyacrylamide polymer, the pitch is removed with the finished product rather than being left to accumulate and deposit on the paper machine and process equipment. This is evident in mill trials where the concentration of colloidally dispersed wood resins, as determined by the method of Allen, L.H., Trans. Tech. Sect. CPPA, 3, 32 (1977), has been reduced whilst simultaneously increasing the amount of organic material extractable from the paper with dichloromethane. Further evidence of pitch control is observed by increases in the friction of the paper as the "slippery" pitch is removed from the fibre surface and fixed within the DIACHEM WHITE CARBON par-ticles. Another advantage of the high surface area and voidvolume is the ability of the pigment to reduce oil vehicle penetration in the offset and letterpress printing processes.
By reducing oil vehicle penetration, print through, which is defined as the extent to which print on one side of paper is visible from the opposite side, is reduced and hence print quality is improved.
The other component of the novel combination of the invention is a high molecular weight cationic polyacrylamide polymer with properties that do not tend to bind the DIACHEM
WHITE CARBON particles together, but retain the fibre retention qualities. At the same time, the polyacrylamide polymer should contribute to the dispersion of the DIACHEM WHITE CARBON
particles throughout the cellulose fibre mat.
The polyacrylamide polymer should have an average molecular weight of between 100,000 and 50,000,000, preferably between 5,000,000 and 12,000,000. The cationic charge is based on acrylamide plus one of the following cationic quaternary ammonium monomers, dimethylaminoethyl acrylate, dimethyl sulfate quaternary; dimethylaminoethyl acrylate, methyl chloride quaternary or 2-hydroxy-n-propyldimethylamino acrylate, methyl chloride quaternary, and the charge density is less than 30 mole percent, preferably less than 12 mole percent.
The high molecular weight cationic polyacrylamide polymer should be selected according to specific individual characteristics of each paper mill, because each mill has different cellulose fibre furnishes, and different operating criteria. Nonetheless, within the broad parameters of the overall invention, high performance standards utilizing the DIACHEM WHITE CARBON - polyacrylamide polymer combination of the invention should be obtainable.
Performance Tests The inventors have conducted several trials to demonstrate the effectiveness of the novel DIACHEM WHITE CARBON-high molecular weight cationic polyacrylamide polymer combination of the invention.
Figure 1 illustrates results of a mill evaluation for newsprint containing DIACHEM WHITE CARBON treated with polyacryl-amide polymer. It is evident that as the percent pigment retained in the paper increases, the friction of the paper increases as shown by the increase in slip angle.
Figure 2 illustrates that concurrent with the slip angle increase depicted in Figure 1 there is a reduction in the colloidal pitch concentration in the white water, the filtrate obtained after separation of the fibres in the papermaking process, and an increase in the percent dichloromethane extract-ables for the paper. This is consistent with the DIACHEM WHITE
202~207 CARBON binding the pitch and subsequently retaining it within the cellulose fibre mat.
Table 3 below depicts a comparison of the white carbon product of the invention, identified with the trade-mark DIACHEM
WHITE CARBON, compared to another commercially available white carbon product, with different physical properties. For discussion purposes, the other product is identified with the term Product A.
Table 3 Product comParison Physical Properties DIACHEM WHITE CARBON Product A
Brightness @ 460nm 98 94 Crystal Structure Amorphous Amorphous Average Particle size 4 microns 4 microns BET Surface Area m2/g 110 60 Tamped Density g/liter 170 289 Oil Absorption cc/100 g 190 120 Figure 3 illustrates a plot of slip angle versus percent product, comparing Product A and DIACHEM WHITE CARBON.
The plot demonstrates that slip angle performance for DIACHEM
WHITE CARBON treated with the polyacrylamide polymer, according to the invention, performs substantially better than the Product A aluminosilicate treated with the same polyacrylamide polymer, presumably because of the higher surface area and oil absorption capabilities of the DIACHEM WHITE CARBON.
Table 4 below gives the measured print through for laboratory offset-printed newsprint samples produced in a North American paper mill on separate machines at two basis weights but using the same furnish. The paper produced on papermachine #3 contained on average 1.2~ DIACHEM WHITE CARBON treated with polyacrylamide polymer, according to the invention whilst the ` ~_ paper produced on papermachine #l did not. The DIACHEM WHITE
CARBON containing paper shows reduced print through which can be attributed to the high surface area and oil absorption capabil-ities of the pigment preventing oil vehicle penetration in the offset printing process.
Table 4 Print Through Results for Offset-Printed Paper Samples Basis Weight: 48.8 g~m2 PM #1 PM #3% Reduction Conveying Wire Side 0.065 0.045 31 Backing Wire Side 0.065 0.044 32 Basis Weight: 45.1 q/m2 Conveying Wire Side 0.076 0.052 35 Backing Wire Side 0.078 0.050 36 Figure 4 illustrates a scanning electronmicrograph of a sample of newsprint treated with the DIACHEM WHITE CARBON-polyacrylamide polymer combination of the invention. The bar represents a 5 micrometer enlargement. It is apparent the particles are well distributed throughout the cellulose mass.
Figure 5 illustrates elemental mapping on the silica portion of the filler, distributed throughout a paper mat produced utilizing the combination DIACHEM WHITE CARBON-poly-acrylamide polymer of the invention, the bar representing 5 microns. As can be seen, the silica is evenly distributed throughout the cellulose mat. Two concentrations occur at points F and G, but these are minor in size and number and are not considered to be significant.
Figure 6 represents a transmission electronmicrograph of cellulose fibres treated with the DIACHEM WHITE CARBON-polyacrylamide polymer according to the invention. It is evident 202~207 -that the DIACHEM WHITE CARBON-polyacrylamide polymer agglomerated groups are well distributed throughout the cellulose fibre mass.
Figure 7 illustrates a scanning electronmicrograph of the end of a paper sheet produced from cellulose fibres treated with the DIACHEM WHITE CARBON-polyacrylamide polymer according to the invention. As can be readily seen, there is a good distribution of the silica agglomerations throughout the paper sheet from top to bottom.
As will be apparent to those skilled in the art in the light of the foregoing disclosure, many alterations and modifica-tions are possible in the practice of this invention without departing from the spirit or scope thereof. Accordingly, the scope of the invention is to be construed in accordance with the substance defined by the following claims.
FIELD OF THE INVENTION
This invention pertains to novel bonded white paper pigments used in paper products. More particularly, this invention relates to novel combinations of precipitated sodium aluminosilicate and cationic polyacrylamide polymer which together provide superior brightness, friction qualities and printability to newsprint and ground wood specialties, while at the same time decreasing pitch deposition on papermaking equipment.
BACKGROUND OF THE INVENTION
Precipitated silicas and silicates have been used for many years as auxiliaries in rubber and plastics, as feedstuff additives and as fillers for paper products. One family of silicates is manufactured by reacting sodium silicate (water glass) with aluminum sulphate and sulphuric acid to precipitate a sodium aluminosilicate.
Silicas and silicates are obtainable in the marketplace from corporations such as Tokuyama Soda Co. Ltd., Japan, J.M.
Huber Corporation, U.S.A., Degussa, West Germany, Akzo Chemicals Inc., West Germany and Rhône Poulenc, France. In Japan, precipitated silicas and silcates are widely used in paper products, including newsprint, to improve print quality and to reduce paper "snaking" in the pressroom.
In North America, there is a strong growing trend to include pigments in newsprint in order to produce a higher quality newspaper. For instance, in the United States, the newspaper, U.S.A. Today, which is computer type-set and trans-mitted by telecommunication to various paper publishing houses throughout the United States, has set high standard specifica-tions for the newsprint that is used in publishing its daily 1 - `.L
newspaper. The newsprint must be of a specified level of bright-ness, opacity, smoothness, and have minimum colour bleed-through. The specifications for the U.S.A. Today newsprint are sufficiently high that most newsprint paper mills in North America cannot meet the specifications without inclusion of some kind of pigment in the paper.
In the manufacture of newsprint and groundwood specialties, it is important to retain as many of the valuable cellulose fibers as possible. Lost fibres increase the overall manufacturing cost of the newsprint. Retention aids have been developed for the purpose of retaining fibres in newsprint.
These retention aids are usually polymeric materials which flocculate the cellulose fibres together, thereby minimizing fibre loss. Polymers used as retention aids include polyacryl-amides, polyethyleneimines, polyethyleneoxide and modified starch.
To date, it has been difficult to be able to use precipitated sodium aluminosilicate, in conjunction with all retention aids in the manufacture of newsprint without incurring certain disadvantages. Certain retention aids tend to agglomer-ate the sodium aluminosilicate particles into groups, thereby negating an even distribution of the sodium aluminosilicate particles throughout the newsprint fibres. To offset this phenomenon, a higher volume of sodium aluminosilicate must be added to the newsprint, which increases cost and tends to adversely decrease the quality of the treated newsprint.
Moreover, retention aids which tie together sodium aluminosili-cate particles will be less effective at performing their secondfunction, that is, retaining cellulose fibres together.
The performance of retention aids can also be detri-mentally affected by the presence of wood resin in the furnish.
In this discussion, wood resin present in wood and wood pulps is used to denote a complex agglomeration of organic materials such as terpenes, fatty acids, resin acids, esters and unsaponi-fiables. These wood resins are water insoluble components whichare present on the surfaces of fibres and in the form of colloidal droplets in the papermaking process water. In addition to interfering with the performance of retention aids, the wood resin may accumulate thus leading to pitch deposition on the surfaces of the process equipment. In the past, the most common chemical methods for controlling pitch deposition have included the use of talc, dispersants, alum and sodium aluminate.
The invention is directed to novel compositions useful in minimizing pitch deposition and removing pitch from paper-making equipment whilst improving the brightness, friction and 15printability qualities of cellulose paper comprising: (a) a precipitated sodium aluminosilicate having a primary particle in the range of about 10 to 60 nanometers which are agglomerated into particles in the size range of about 1 to 50 microns; and (b) a high molecular weight cationic polyacrylamide polymer 20having a molecular weight of about lOO,oOO to about 50,000,000.
The high molecular weight cationic charge poly-acrylamide polymer may be of a molecular chain length suffi-ciently long that-it does not have the effect of coagulating the sodium aluminosilicate particles together when the composition is added to newsprint pulp suspension.
The invention in a specific aspect is directed to a composition useful in reducing the accumulation of pitch on paper processing equipment and improving the brightness qualities of cellulose paper comprising: (a) a precipitated sodium alumino-silicate having a primary particle size in the range of about 25 to about 35 nanometers, and secondary agglomerations of about 3 to 5 microns; and (b) a high molecular weight cationic poly-acrylamide polymer having an average molecular weight in therange of about 5,000,000 to 12,000,000.
-The cationic charge in the polyacrylamide polymer can be based on acrylamide plus a substance selected from the group consisting of cationic quaternary ammonium monomers, dimethylaminoethyl acrylate, dimethyl sulfate quaternary;
dimethylaminoethyl acrylate, methyl chloride quaternary; and 2-hydroxy-n-propyldimethylamino acrylate, methyl chloride quater-nary. The charge density of the polyacrylamide polymer may be less than about 30 mole percent or may less than about 12 mole percent.
The secondary agglomerations of the sodium alumino-silicate may have a size range wherein about 5% of the particles have diameters greater than about 10 to 15 microns, about 50% of the particles have diameters greater than about 3 to 5 microns, and about 95% of the particles have diameters greater than about 2 to 3 microns.
The sodium aluminosilicate may have the following physical properties:
Brightness Q 460nm - 98 Crystal Structure - Amorphous Primary Particle Size nm - 25 - 35 Average Particle size, ~m - 3 - 5 BET Surface Area m2/g - 80 - 100 Tamped Density g/litre - 170 - 210 Oil Absorption cc/100 g - 180 - 200 The invention is also directed to a method of reducing the accumulation of pitch on paper processing equipment which comprises adding to paper furnish supplied to the paper process-ing equipment a composition comprising: (a) a precipitated sodium aluminosilicate having a primary particle size in the range of about 10 to 60 nanometers, and secondary agglomerations of about 1 to 50 microns; and (b) a high molecular weight cationic polyacrylamide polymer having an average molecular weight in the range of about 100,000 to about 50,000,000.
DRAWINGS
In drawings which depict specific embodiments of the invention, but which should not be construed as restricting the spirit or scope of the invention in any way:
Figure 1 illustrates increases in slip angle obtained in a mill evaluation for newsprint treated with DIACHEM WHITE
CARBON(TM) and polyacrylamide polymer.
Figure 2 illustratés the reduction in colloidal pitch and increase in percent dichloromethane extractables during the same period of the mill evaluation as illustrated in Figure 1.
Figure 3 illustrates a plot of slip angle versus percent filler product of handsheets filled with two types of sodium aluminosilicate product, both treated with polyacrylamide polymer;
Figure 4 illustrates a scanning electronmicrograph of a cellulose fiber mat treated with DIACHEM WHITE CARBON, the reference line representing five microns;
Figure 5 illustrates a molecular mapping of silica atoms distributed in newsprint treated with a DIACHEM WHITE
CARBON polyacrylamide mixture according to the invention;
Figure 6 illustrates a transmission electronmicrograph of newsprint treated with a DIACHEM WHITE CARBON polyacrylamide mixture according to the invention, the reference line represent-ing five microns; and Figure 7 illustrates a scanning electronmic~oy~aph of the edge of a paper sheet treated with the DIACHEM WHITE CARBON
polyacrylamide mixture according to the invention as illustrated in Figure 6.
2~20207 -DETAILED DESCRIPTION OF SPECIFIC
EMBODIMENTS OF THE INVENTION
The inventors have discovered that a mixture of sodium aluminosilicate (DIACHEM WHITE CARBON) of certain specifications, in conjunction with a high molecular weight cationic polyacryl-amide polymer is advantageous in treating cellulose pulp suspension during the manufacture of paper such as newsprint to obtain a high quality filled paper, including newsprint.
Specifically, this invention is applicable to furnishes based on mech~n;cal pulp and in part semi-bleached kraft pulp, unbleached kraft pulp, and/or unbleached sulfite pulp. Advantages of treatment include reduced pitch deposition on the paper machine, and because of even distribution of white carbon throughout the cellulose fibre mat, increased brightness, enhanced friction qualities and reduced print through in offset and letterpress printing, are obtained.
The precipitated sodium aluminosilicate component of the invention (DIACHEM WHITE CARBON(TM)) should preferably have a chemical composition approximating the chemical composition depicted in Table 1 below:
Table 1 DIACHEM WHITE CARBON Sodium Aluminosilicate Chemical ComPosition sio2 - 71.0%
Al2O3 - 8.0%
CaO - 0.2%
Na2O - 7.0%
H2O - 5.0%
LOI (incl. H20) - 13.0%
Impurities (Fe, other heavy metals) less than 0.05%
The precipitated silicate product used in the inven-tion, described with the trade-mark DIACHEM WHITE CARBONtTM), should have physical properties approximating those depicted in Table 2 below:
Table 2 DIACHEM WHITE CARBON
Physical Properties Brightness Q 46Onm - 98 Crystal Structure - Amorphous Primary Particle Size nm - 25 - 35 Average Particle size, ~m - 3 - 5 BET Surface Area m2/g - 80 - 100 Tamped Density g/litre - 170 - 210 Oil Absorption cc/100 g - 180 - 200 Valley Abrasion #, mg wire loss - 4 - 10 The DIACHEM WHITE CARBON(TM) product used in the invention should have particle diameters of 1-50 ~m, with particles of over 45 ~m (325 mesh sieve residue) at a ratio of under 0.4%, or ideally under 0.1%. The particle size distribu-tion, measured by the Coulter Counter method with a 100 ~m capillary, should be such that 5% of the particles have diameters greater than 10-15 ~m, 50% have diameters greater than 3-5 ~m, and 95% have diameters greater than 2-3 ~m. The "cauliflower-like" sodium aluminosilicate particles are comprised of agglomer-ations of smaller primary particles which are preferably in the range of 25-35 ~m. The distinct morphology of the secondary agglomerations have been shown to have a number of important advantages as discussed below:
1. A high surface area which increases fiber-pigment-air interfaces for improved scattering of incident light and thereby alters the optical properties of newsprint sheet.
In mill trials, brightness increases of 1.2 - 1.7 points per one -percent retained DIACHEM WHITE CARBON have been achieved with no adverse effect on printing opacity.
2. A high void volume, as indicated by the oil absorption value, combined with a high surface area, provides to the furnish sites for the effective binding of pitch and the wood resin precursor. With subsequent retention of the pitch-containing DIACHEM WHITE CARBON particles in the paper through the use of the polyacrylamide polymer, the pitch is removed with the finished product rather than being left to accumulate and deposit on the paper machine and process equipment. This is evident in mill trials where the concentration of colloidally dispersed wood resins, as determined by the method of Allen, L.H., Trans. Tech. Sect. CPPA, 3, 32 (1977), has been reduced whilst simultaneously increasing the amount of organic material extractable from the paper with dichloromethane. Further evidence of pitch control is observed by increases in the friction of the paper as the "slippery" pitch is removed from the fibre surface and fixed within the DIACHEM WHITE CARBON par-ticles. Another advantage of the high surface area and voidvolume is the ability of the pigment to reduce oil vehicle penetration in the offset and letterpress printing processes.
By reducing oil vehicle penetration, print through, which is defined as the extent to which print on one side of paper is visible from the opposite side, is reduced and hence print quality is improved.
The other component of the novel combination of the invention is a high molecular weight cationic polyacrylamide polymer with properties that do not tend to bind the DIACHEM
WHITE CARBON particles together, but retain the fibre retention qualities. At the same time, the polyacrylamide polymer should contribute to the dispersion of the DIACHEM WHITE CARBON
particles throughout the cellulose fibre mat.
The polyacrylamide polymer should have an average molecular weight of between 100,000 and 50,000,000, preferably between 5,000,000 and 12,000,000. The cationic charge is based on acrylamide plus one of the following cationic quaternary ammonium monomers, dimethylaminoethyl acrylate, dimethyl sulfate quaternary; dimethylaminoethyl acrylate, methyl chloride quaternary or 2-hydroxy-n-propyldimethylamino acrylate, methyl chloride quaternary, and the charge density is less than 30 mole percent, preferably less than 12 mole percent.
The high molecular weight cationic polyacrylamide polymer should be selected according to specific individual characteristics of each paper mill, because each mill has different cellulose fibre furnishes, and different operating criteria. Nonetheless, within the broad parameters of the overall invention, high performance standards utilizing the DIACHEM WHITE CARBON - polyacrylamide polymer combination of the invention should be obtainable.
Performance Tests The inventors have conducted several trials to demonstrate the effectiveness of the novel DIACHEM WHITE CARBON-high molecular weight cationic polyacrylamide polymer combination of the invention.
Figure 1 illustrates results of a mill evaluation for newsprint containing DIACHEM WHITE CARBON treated with polyacryl-amide polymer. It is evident that as the percent pigment retained in the paper increases, the friction of the paper increases as shown by the increase in slip angle.
Figure 2 illustrates that concurrent with the slip angle increase depicted in Figure 1 there is a reduction in the colloidal pitch concentration in the white water, the filtrate obtained after separation of the fibres in the papermaking process, and an increase in the percent dichloromethane extract-ables for the paper. This is consistent with the DIACHEM WHITE
202~207 CARBON binding the pitch and subsequently retaining it within the cellulose fibre mat.
Table 3 below depicts a comparison of the white carbon product of the invention, identified with the trade-mark DIACHEM
WHITE CARBON, compared to another commercially available white carbon product, with different physical properties. For discussion purposes, the other product is identified with the term Product A.
Table 3 Product comParison Physical Properties DIACHEM WHITE CARBON Product A
Brightness @ 460nm 98 94 Crystal Structure Amorphous Amorphous Average Particle size 4 microns 4 microns BET Surface Area m2/g 110 60 Tamped Density g/liter 170 289 Oil Absorption cc/100 g 190 120 Figure 3 illustrates a plot of slip angle versus percent product, comparing Product A and DIACHEM WHITE CARBON.
The plot demonstrates that slip angle performance for DIACHEM
WHITE CARBON treated with the polyacrylamide polymer, according to the invention, performs substantially better than the Product A aluminosilicate treated with the same polyacrylamide polymer, presumably because of the higher surface area and oil absorption capabilities of the DIACHEM WHITE CARBON.
Table 4 below gives the measured print through for laboratory offset-printed newsprint samples produced in a North American paper mill on separate machines at two basis weights but using the same furnish. The paper produced on papermachine #3 contained on average 1.2~ DIACHEM WHITE CARBON treated with polyacrylamide polymer, according to the invention whilst the ` ~_ paper produced on papermachine #l did not. The DIACHEM WHITE
CARBON containing paper shows reduced print through which can be attributed to the high surface area and oil absorption capabil-ities of the pigment preventing oil vehicle penetration in the offset printing process.
Table 4 Print Through Results for Offset-Printed Paper Samples Basis Weight: 48.8 g~m2 PM #1 PM #3% Reduction Conveying Wire Side 0.065 0.045 31 Backing Wire Side 0.065 0.044 32 Basis Weight: 45.1 q/m2 Conveying Wire Side 0.076 0.052 35 Backing Wire Side 0.078 0.050 36 Figure 4 illustrates a scanning electronmicrograph of a sample of newsprint treated with the DIACHEM WHITE CARBON-polyacrylamide polymer combination of the invention. The bar represents a 5 micrometer enlargement. It is apparent the particles are well distributed throughout the cellulose mass.
Figure 5 illustrates elemental mapping on the silica portion of the filler, distributed throughout a paper mat produced utilizing the combination DIACHEM WHITE CARBON-poly-acrylamide polymer of the invention, the bar representing 5 microns. As can be seen, the silica is evenly distributed throughout the cellulose mat. Two concentrations occur at points F and G, but these are minor in size and number and are not considered to be significant.
Figure 6 represents a transmission electronmicrograph of cellulose fibres treated with the DIACHEM WHITE CARBON-polyacrylamide polymer according to the invention. It is evident 202~207 -that the DIACHEM WHITE CARBON-polyacrylamide polymer agglomerated groups are well distributed throughout the cellulose fibre mass.
Figure 7 illustrates a scanning electronmicrograph of the end of a paper sheet produced from cellulose fibres treated with the DIACHEM WHITE CARBON-polyacrylamide polymer according to the invention. As can be readily seen, there is a good distribution of the silica agglomerations throughout the paper sheet from top to bottom.
As will be apparent to those skilled in the art in the light of the foregoing disclosure, many alterations and modifica-tions are possible in the practice of this invention without departing from the spirit or scope thereof. Accordingly, the scope of the invention is to be construed in accordance with the substance defined by the following claims.
Claims (19)
1. A composition useful in reducing the accumulation of pitch on paper processing equipment and improving the brightness qualities of cellulose paper comprising:
(a) a precipitated sodium aluminosilicate having a primary particle size in the range of about 10 to about 60 nanometers, and secondary agglomerations of about 1 to 50 microns; and (b) a high molecular weight cationic polyacrylamide polymer having an average molecular weight in the range of about 100,000 to 50,000,000.
(a) a precipitated sodium aluminosilicate having a primary particle size in the range of about 10 to about 60 nanometers, and secondary agglomerations of about 1 to 50 microns; and (b) a high molecular weight cationic polyacrylamide polymer having an average molecular weight in the range of about 100,000 to 50,000,000.
2. A composition as claimed in claim 1 wherein the polyacrylamide polymer has an average molecular weight in the range of about 5,000,000 to 12,000,000.
3. A composition as claimed in claim 1 wherein the cationic charge in the polyacrylamide polymer is based on acrylamide plus a substance selected from the group consisting of cationic quaternary ammonium monomers, dimethylaminoethyl acrylate, dimethyl sulfate quaternary; dimethylaminoethyl acrylate, methyl chloride quaternary; and 2-hydroxy-n-propyl-dimethylamino acrylate, methyl chloride quaternary.
4. A composition as claimed in claim 3 wherein the charge density of the polyacrylamide polymer is less than about 30 mole percent.
5. A composition as claimed in claim 3 wherein the charge density of the polyacrylamide polymer is less than about 12 mole percent.
6. A composition as claimed in claim 1 wherein the primary particle size of the sodium aluminosilicate is in the range of about 25 to about 35 nanometers.
7. A composition as claimed in claim 1 wherein the secondary agglomerations of the sodium aluminosilicate have a size range wherein about 5% of the particles have diameters greater than about 10 to 15 microns, about 50% of the particles have diameters greater than about 3 to 5 microns, and about 95%
of the particles have diameters greater than about 2 to 3 microns.
of the particles have diameters greater than about 2 to 3 microns.
8. A composition as claimed in claim 1 wherein the sodium aluminosilicate has the following physical properties:
Brightness @ 460nm - 98 Crystal Structure - Amorphous Primary Particle Size nm - 25 - 35 Average Particle size, µm - 3 - 5 BET Surface Area m2/g - 80 - 100 Tamped Density g/litre - 170 - 210 Oil Absorption cc/100 g - 180 - 200
Brightness @ 460nm - 98 Crystal Structure - Amorphous Primary Particle Size nm - 25 - 35 Average Particle size, µm - 3 - 5 BET Surface Area m2/g - 80 - 100 Tamped Density g/litre - 170 - 210 Oil Absorption cc/100 g - 180 - 200
9. A composition as claimed in claim 1 wherein the high molecular weight cationic polyacrylamide polymer has a molecular chain length sufficiently long that it does not have the effect of coagulating the sodium aluminosilicate particles when the composition is added to cellulose fibre paper.
10. A method of reducing the accumulation of pitch on paper processing equipment which comprises adding to paper furnish supplied to the paper processing equipment a composition comprising:
(a) a precipitated sodium aluminosilicate having a primary particle size in the range of about 10 to 60 nanometers, and secondary agglomerations of about 1 to 50 microns; and (b) a high molecular weight cationic polyacrylamide polymer having an average molecular weight in the range of about 100,000 to about 50,000,000.
(a) a precipitated sodium aluminosilicate having a primary particle size in the range of about 10 to 60 nanometers, and secondary agglomerations of about 1 to 50 microns; and (b) a high molecular weight cationic polyacrylamide polymer having an average molecular weight in the range of about 100,000 to about 50,000,000.
11. A method as claimed in claim 10 wherein the polyacryl-amide polymer has an average molecular weight in the range of about 5,000,000 to 12,000,000.
12. A method as claimed in claim 10 wherein the cationic charge in the polyacrylamide polymer is based on acrylamide plus a substance selected from the group consisting of cationic quaternary ammonium monomers, dimethylaminoethyl acrylate, dimethyl sulfate quaternary; dimethylaminoethyl acrylate, methyl chloride quaternary; and 2-hydroxy-n-propyldimethylamino acrylate, methyl chloride quaternary.
13. A method as claimed in claim 12 wherein the charge density of the polyacrylamide polymer is less than about 30 mole percent.
14. A method as claimed in claim 12 wherein the charge density of the polyacrylamide polymer is less than about 12 mole percent.
15. A method as claimed in claim 10 wherein the primary particle size of the sodium aluminosilicate is in the range of about 25 to about 35 nanometers.
16. A method as claimed in claim 10 wherein the secondary agglomerations of the sodium aluminosilicate have a size range wherein about 5% of the particles have diameters greater than about 10 to 15 microns, about 50% of the particles have diameters greater than about 3 to 5 microns, and about 95% of the particles have diameters greater than about 2 to 3 microns.
17. A method as claimed in claim 10 wherein the sodium aluminosilicate has the following physical properties:
Brightness @ 460nm - 98 Crystal Structure - Amorphous Primary Particle Size nm - 25 - 35 Average Particle size, µm - 3 - 5 BET Surface Area m2/g - 80 - 100 Tamped Density g/litre - 170 - 210 Oil Absorption cc/100 g - 180 - 200
Brightness @ 460nm - 98 Crystal Structure - Amorphous Primary Particle Size nm - 25 - 35 Average Particle size, µm - 3 - 5 BET Surface Area m2/g - 80 - 100 Tamped Density g/litre - 170 - 210 Oil Absorption cc/100 g - 180 - 200
18. A method as claimed in claim 10 wherein the high molecular weight cationic polyacrylamide polymer has a molecular chain length sufficiently long that it does not have the effect of coagulating the sodium aluminosilicate particles when the composition is added to cellulose fibre paper.
19. A method of improving the brightness of cellulose fibre paper which comprises adding during the paper manufacturing process a combination of a sodium aluminosilicate having a primary particle size in the range of 10 to 60 nanometers and secondary agglomerations in the size range of about 1 to 50 microns nod a cationic charge polyacrylamide polymer having an average molecular weight of about 100,000 to about 50,000,000.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2020207 CA2020207C (en) | 1990-06-29 | 1990-06-29 | Bonded paper pigments |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2020207 CA2020207C (en) | 1990-06-29 | 1990-06-29 | Bonded paper pigments |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2020207A1 CA2020207A1 (en) | 1991-12-30 |
| CA2020207C true CA2020207C (en) | 1996-06-25 |
Family
ID=4145385
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2020207 Expired - Fee Related CA2020207C (en) | 1990-06-29 | 1990-06-29 | Bonded paper pigments |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2020207C (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8758522B2 (en) | 2007-12-14 | 2014-06-24 | Lam Research Corporation | Method and apparatus for removing contaminants from substrate |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB9410920D0 (en) * | 1994-06-01 | 1994-07-20 | Allied Colloids Ltd | Manufacture of paper |
-
1990
- 1990-06-29 CA CA 2020207 patent/CA2020207C/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8758522B2 (en) | 2007-12-14 | 2014-06-24 | Lam Research Corporation | Method and apparatus for removing contaminants from substrate |
Also Published As
| Publication number | Publication date |
|---|---|
| CA2020207A1 (en) | 1991-12-30 |
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