EP0041056B1 - Papermaking - Google Patents

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Publication number
EP0041056B1
EP0041056B1 EP81850084A EP81850084A EP0041056B1 EP 0041056 B1 EP0041056 B1 EP 0041056B1 EP 81850084 A EP81850084 A EP 81850084A EP 81850084 A EP81850084 A EP 81850084A EP 0041056 B1 EP0041056 B1 EP 0041056B1
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EP
European Patent Office
Prior art keywords
silicic acid
cationic starch
colloidal silicic
stock
binder
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP81850084A
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German (de)
English (en)
French (fr)
Other versions
EP0041056A1 (en
Inventor
Per Gunnar Bätelson
Hans Erik Johansson
Hans Magnus Larsson
Olof Sundén
Per Johan Svending
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nouryon Pulp and Performance Chemicals AB
Original Assignee
Eka AB
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Filing date
Publication date
Priority claimed from SE8003948A external-priority patent/SE432951B/sv
Priority claimed from US06/238,645 external-priority patent/US4385961A/en
Application filed by Eka AB filed Critical Eka AB
Publication of EP0041056A1 publication Critical patent/EP0041056A1/en
Application granted granted Critical
Publication of EP0041056B1 publication Critical patent/EP0041056B1/en
Expired legal-status Critical Current

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Classifications

    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
    • D21H17/63—Inorganic compounds
    • D21H17/67—Water-insoluble compounds, e.g. fillers, pigments
    • D21H17/68—Water-insoluble compounds, e.g. fillers, pigments siliceous, e.g. clays
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F1/00—Wet end of machines for making continuous webs of paper
    • D21F1/66—Pulp catching, de-watering, or recovering; Re-use of pulp-water
    • D21F1/82—Pulp catching, de-watering, or recovering; Re-use of pulp-water adding fibre agglomeration compositions
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
    • D21H17/20—Macromolecular organic compounds
    • D21H17/21—Macromolecular organic compounds of natural origin; Derivatives thereof
    • D21H17/24—Polysaccharides
    • D21H17/28—Starch
    • D21H17/29—Starch cationic
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
    • D21H21/50—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties characterised by form
    • D21H21/52—Additives of definite length or shape
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H23/00—Processes or apparatus for adding material to the pulp or to the paper
    • D21H23/76—Processes or apparatus for adding material to the pulp or to the paper characterised by choice of auxiliary compounds which are added separately from at least one other compound, e.g. to improve the incorporation of the latter or to obtain an enhanced combined effect
    • D21H23/765—Addition of all compounds to the pulp

Definitions

  • the present invention relates generally to paper-making processes and, more particularly, to the use of a binder in a papermaking process, the binder comprising a complex of cationic starch and colloidal silicic acid to produce a paper having increased strength and other characteristics.
  • a binder in addition, also effects highly improved levels of retention of added mineral materials as well as papermaking fines.
  • various features of the invention may be employed to effect clarification of the white water resulting from a papermaking process.
  • the principal object of the invention is the provision of a binder system and method which produce improved properties in paper and which will permit the use of minimum amounts of fiber to attain strengths and other properties which are required.
  • Another object of the invention is the provision of a binder system and a method of employing it which materially increases the strength and other characteristics of paper as compared to a similar paper made with known binders.
  • An additional object of the invention is the provision of a binder and a method of employing it which maximizes retention of mineral filler and other materials in the paper sheet when used in the stock on the papermaking machine.
  • a further object of the invention is the provision of a paper having high mineral concentration which has acceptable strength and other characteristics.
  • a final object is the provision for a method of removing suspended solids from white water in a papermaking process.
  • a binder and method of employing it which materially increases the strength and other characteristics of a paper product and which permits the use of substantial amounts of mineral fillers in a papermaking process while maximizing the retention of the filler and cellulosic fines in the sheet.
  • This makes possible, for a given grade of paper, a reduction in the cellulosic fiber content of the sheet and/or the quality of the cellulosic fiber employed without undue reduction in the strength and other characteristics of the sheet.
  • the amount of mineral filler material may be increased without unduly reducing the strength and other characteristics of the resulting paper product.
  • the reduction in fiber content permits a reduction in the energy required for pulping as well as a reduction in the energy required for drying the sheet.
  • the retention of the mineral filler and fines is at a sufficiently high level that white water problems are minimized.
  • the system of the invention includes the use of a binder complex which involves two components, i.e. colloidal silicic acid and cationic starch.
  • the weight ratio between the cationic starch and the Si0 2 in the colloidal silicic acid is between 1:1 and 25:1.
  • the two components are provided in the stock prior to formation of the paper product on the papermaking machine. It has been found that, after drying, the sheet has greatly enhanced strength characteristics. Also, it has been found that when mineral fillers such as clay, chalk and the like are employed in the stock, these mineral fillers are efficiently retained in the sheet and further do not have the degree of deleterious effect upon the strength of the sheet that will be observed when the binder system is not employed.
  • the cationic starch and the anionic colloidal silicic acid form a complex agglomerate which is bound together by the anionic colloidal silicic acid, and that the cationic starch becomes associated with the surface of the mineral filler material whose surface is either totally or partially anionic.
  • the cationic starch also becomes associated with the cellulosic fiber and the fines, both of which are anionic.
  • the association between the agglomerate and the cellulosic fibers provides extensive hydrogen bonding. This theory is supported in part by the fact that as the Zeta potential in the anionic stock moves towards zero when employing the binder complex of the invention both the strength characteristics and the retention improve.
  • the effect of the binder system may be enhanced by adding the colloidal silicic acid component in several increments, i.e. a portion of the colloidal silicic acid is admixed with the pulp and the mineral filler when present, then the cationic starch is added and thereafter when a complex agglomerate of pulp, filler (if any), silicic acid and starch is formed and before the stock is fed to the head box of the papermaking machine the remaining portion of the colloidal silicic acid is admixed with the stock containing the complex agglomerate.
  • This procedure of supplying the colloidal silicic acid in two or more steps results in certain improvements in strength and other characteristics, but the most striking improvement is the increase in retention of filler and papermaking fines.
  • the reason for these improvements is not entirely understood but it is believed that they result from the production of complex filler-fiber-binder agglomerates, which are more stable, i.e. that the later addition of the colloidal silicic acid causes the agglomerates initially formed to bond together to form even more stable agglomerates which are less sensitive to mechanical and other forces during the formation of the paper.
  • the presence of over 50% by weight of cellulosic fibers is essential to obtain certain of the improved results in the invention which occur because of the interaction or association of agglomerate and the cellulosic fibers.
  • the finished paper contains over 50% by weight of cellulosic fiber, the paper produced will have greatly improved properties as compared to paper made from similar stocks not employing the binder agglomerate described herein.
  • Mineral filler material which can be employed includes any of the common mineral fillers which have a surface which is at least partially anionic in character. Mineral fillers such as kaolin (china clay), bentonite, titanium dioxide, chalk, and talc all may be employed satisfactorily. (The term “mineral fillers” as used herein includes in addition to the foregoing materials, wollastonite and glass fibers and also low-density mineral fillers such as expanded perlite). When the binder complex disclosed herein is employed, the mineral fillers will be substantially retained in the finished product and the paper produced will not have its strength degraded to the degree observed when the binder is not employed.
  • the mineral filler is normally added in the form of an aqueous slurry in the usual concentrations employed for such fillers.
  • the mineral fillers in the paper may consist of or comprise a low-density or bulky filler.
  • the possibility of adding such fillers to conventional paper stocks is limited by factors such as the retention of the fillers on the wire, the dewatering of the paper stock on the wire, the wet and dry strength of the paper product obtained.
  • We have now discovered that the problems caused by the addition of such fillers can be obviated or substantially eliminated by using the binder complex of the present invention which also makes it possible to add higher than normal proportions of such fillers to obtain special properties in the paper product.
  • the binder complex of the invention it has become possible to produce a paper product of lower density and consequently higher stiffness at the same grammage and simultaneously to keep the strength properties of the paper product (such as the modulus of elasticity, the tensile index, the tensile energy absorption and the surface picking resistance) at the same level as or even at a better level than before.
  • the strength properties of the paper product such as the modulus of elasticity, the tensile index, the tensile energy absorption and the surface picking resistance
  • the binder comprises a combination of colloidal silicic acid and cationic starch.
  • the colloidal silicic acid may take various forms, for example, it may be in the form of polysilicic acid or colloidal silicic acid sols although best results are obtained through the use of colloidal silica sols.
  • Polysilicic acid can be made by reacting water glass with sulfuric acid by known procedures to provide molecular weights (as Si0 2 ) up to about 100,000.
  • the resulting polysilicic acid is unstable and difficult to use and presents a problem in that the presence of sodium sulfate causes corrosion and other problems in papermaking and white water disposal.
  • the sodium sulfate may be removed by ion exchange through the use of known methods but the resulting polysilicic acid is unstable and without stabilization will deteriorate on storage.
  • Salt-free polysilicic acid may also be produced by direct ion exchange of diluted water glass.
  • the colloidal silicic acid in the sol should desirably have a surface area of from 50 to 1000 m 2 /g and preferably a surface area from 200 to 1000 m 2 /g with best results being observed when the surface area is between 300 to 700 m 2 /g.
  • the silicic acid sol is stabilized with an alkali having a molar ratio of Si0 2 to M 2 0 of from 10:1 to 300:1 and preferably a ratio of from 15:1 to 100:1 (M is an ion selected from the group consisting of Na, K, Li and NH 4 ). It has been determined that the size of the colloidal silicic acid particles should be under 20 nm and preferably should have an average size ranging from 10 down to 1 nm. (A colloidal silicic acid particle having a surface area of about 500 m 2 /g involves an average particle size of about 5.5 nm).
  • silicic acid sol having colloidal silicic acid particles which have a maximum active surface and a well defined small size generally averaging 4-9 nm.
  • Silicic acid sols meeting the above specifications are commercially available from various sources including Nalco Chemical Company, Du Pont & de Nemours Corporation and the assignee of this invention.
  • the cationic starch which is employed in the binder may be made from starches derived from any of the common starch producing materials, e.g. corn starch, wheat starch, potato starch, rice starch, etc.
  • a starch is made cationic by ammonium group substitution by known procedures. Best results have been obtained when the degree of substitution (d.s.) is between 0.01 and 0.05 and preferably between 0.02 and 0.04, and most preferably over 0.025 and less than 0.04.
  • a cationized starch which was prepared by treating the base starch with either 3-chloro-2-hydroxypropyl-trimethyl ammonium chloride or 2,3-epoxypropyl- trimethyl ammonium chloride to obtain a cationized starch having 0.02-0.04 d.s.
  • the binder is added to the papermaking stock prior to the time that the paper product is formed on the papermaking machine.
  • the two ingredients, the colloidal silicic acid component and the cationic starch may be mixed together to form an aqueous slurry of the silica-cationic starch binder complex which then can be added to and thoroughly mixed with the papermaking stock.
  • this procedure does not provide maximized results.
  • the silica-cationic starch complex is formed in situ in the papermaking stock.
  • colloidal silicic acid component is added to a portion of the stock and thoroughly mixed therewith after which the make-up of the stock is completed and the cationic starch component is added and thoroughly mixed with the stock prior to the formation of the paper product.
  • the final portion or portions of the colloidal silicic acid component are thoroughly mixed with the stock after the initial agglomerate is formed and prior to or at the time the stock is conducted into the head box.
  • the initial addition of the colloidal silicic acid should comprise 20 to 90 percent of the total amount to be added and then, after the initial agglomerate is formed, the remainder should be added before the sheet is formed.
  • the initial addition should comprise from 30 to 80% of the colloidal silicic acid component.
  • the pH of the stock is not unduly critical and may range from a pH of from 4 to 9. However, pH ranges higher than 9 and lower than 4 are undesirable. Also, other paper chemicals such as sizing agents, alum, and the like may be employed but care should be taken that the level of these agents is not great enough to interfere with the formation of the silicic acid cationic starch agglomerate and that the level of the agent in recirculating white water does not become excessive so as to interfere with the formation of the binder agglomerate. Therefore, it is usually preferred to add the agent at a point in the system after the agglomerate is formed.
  • the ratio of cationic starch to the total colloidal silicic acid component should be between 1:1 and 25:1 by weight. Preferably, the ratio is between 1.5:1 and 10:1 and most preferably between 1.5:1 and 4.5:1.
  • the amount of binder to be employed varies with the effect desired and the characteristics of the particular components which are selected in making up the binder. For example, if the binder includes polysilicic acid as the colloidal silicic acid component, more binder will be required than if the colloidal silicic acid component is colloidal silicic acid sol having a surface area of 300 to 700 m 2 /g. Similarly, if the cationic starch, for example, has a d.s. of 0.025 as compared to a d.s. of 0.030, more binder will be required assuming the colloidal silicic acid component is unchanged.
  • the level of binder may range from 0.1 to 15% by weight and preferably from 1 to 15% by weight based upon the weight of the cellulosic fiber.
  • the effectiveness of the binder is greater with chemical pulps so that less binder will be required with these pulps to obtain a given effect than other types.
  • the amount of binder may be based on the weight of the filler material and may range from 0.5 to 25% by weight and usually between 2.5 to 15% by weight of the filler.
  • the binder may be added to the white water of a papermaking machine in a system in which the binder system is not being used.
  • the binder effectively forms an agglomerate with the papermaking fines and the suspended mineral material which makes possible the efficient settling or concentration of the suspended solids to provide a relatively clear fraction of water which can be returned to the papermaking system, and a fraction in which the suspended solids are concentrated and from which they can be removed by filtration or other means.
  • the amount of the binder system or complex required, with the cationic starch to Si02 ratios as set forth above, can be relatively small and in most instances is less than about 10% by weight based upon the dry weight of solids in the white water and the dry weight of the binder system.
  • a useful broad range of the amount of the binder system or complex is from 1 to 20% by weight, preferably from 2 to 10% by weight.
  • FIG. 1 is a flow diagram indicating the sequence of operations.
  • the fiber in the stock comprised a mixture of a mechanical pulp and a chemical pulp.
  • the mechanical pulp was unbleached and was refined to a Canadian Standard Freeness (CSF) of 100.
  • the chemical pulp employed was a bleached sulfate hardwood pulp which was refined to 400 CSF. During the refining process, suitable amounts of water were, of course, added to the pulp to provide the desired consistency.
  • Papermakers' china clay and a colloidal silicic acid sol were dispersed in water to provide a slurry containing 5 percent clay by weight.
  • the china clay had a particle size distribution in the range of from about 0.5 to 10 11 m.
  • the colloidal silicic acid was in the form of a 15% sol which was stabilized with alkali with a molar ratio of S'0 2 :Na,O of 45:1.
  • the silicic acid had a particle size in the range of from about 5-7 nm and a surface area of approximately 500 m 2 /g.
  • the colloidal silicic acid was added to provide 2.86% SiO z based upon the weight of the clay.
  • the pH of the clay-Si0 2 slurry was about 8.
  • Figure 2 shows the level of feed to the papermaking machine during the test run, in kg/min at the various times during the run.
  • the consistency of the stock flowing to the paper machine ranged from about 6 to about 15 g/I, as shown in Figure 2A, the time in Figure 2A being correlated to the times shown in Figure 2.
  • the run was begun at 1410 hours by mixing the chemical pulp and mechanical pulp in the proportions shown.
  • the stock valve was opened and stock flowed to the papermaking machine.
  • the dotted line in Figure 2 shows the adjustment of the stock valve during the process.
  • the stock feed to the machine was constituted entirely of a mixture of chemical and mechanical pulp.
  • the china clay-colloidal silica mixture was introduced into the mixing tank and the papermaking machine was run with the fiber-clay stock until the ash content of the stock and the white water came to equilibrium.
  • a slurry of cationic starch was added to and thoroughly mixed with the pulp, clay and colloidal silicic acid in the mixing tank to provide the stock containing the complete binder.
  • the level of cationic starch added at 1535 hours was 7.14 percent by weight of starch based upon the weight of clay, the ratio of cationic starch to colloidal silicic acid being 2.49.
  • the cationic starch was prepared by treating potato starch with 3-chloro-2-hydroxypropyltrimethylammonium chloride to provide a degree of substitution (d.s.) in the starch of 0.03. It was dispersed in cold water at a concentration of about 4% by weight, heated for 30 min at about 90°C, diluted with cold water to a concentration of about 2% by weight and then added to the mixing tank as indicated in Figure 1.
  • the grammage of the paper rose rapidly as the mineral content in the paper was increased because of the retention of the mineral content with the papermaking fibers on the wire of the machine.
  • the stock valve was then adjusted to reduce the grammage to the 90 g/m 2 level and, by adjustment of the stock valve, the grammage was maintained relatively constant as the ash content rose slowly. During this period of time, the solids in the white water were reduced by approximately 50 percent as more and more of the solid materials were retained.
  • Figure 2B shows the level of solids in the white water. Again, the total concentration of solids exceeds the sum of fiber and ash for the reason given above.
  • the level of ash in this case non-retained minerals
  • the level of cationic starch rises rapidly until the cationic starch at Level 1, has been added and has had a chance to reach equilibrium in the system.
  • the level of cationic starch is increased to Level 2 another dramatic decrease occurs.
  • the combination of the colloidal silicic acid and the cationic starch as a binder also increases the filtering speed of the white water through the wire as shown in Figure 2C.
  • the drainage time per unit volume increased until the combination binder was present at Level 1 and thereafter rapidly decreased.
  • With the addition of the cationic starch at Level 2 the decrease in time per unit volume was even greater.
  • Figure 2D shows the Zeta potential in the stock which is adjusted towards 0 by the addition of the cationic starch component. As will be noted, the adjustment corresponds to increased retention and improved characteristics.
  • Figure 2E graphically illustrates the grammage of the paper during the run. There were two occasions when the web broke on the machine as indicated.
  • Figure 2F is a chart showing the tensile index of the paper produced in this example. It should be noted that, because of the moisture driven from the ash, the amount of china clay in the paper is approximately 120 percent of the amount of ash shown. As will be observed, the tensile index is greatly improved and the clay acts in the presence of the colloidal silica-cationic starch complex binder to increase the tensile index.
  • Figure 2G is a chart similar to Figure 2F, except that the tensile index is correlated to the level of chemical pulp.
  • Figure 2H shows the improved Z strengths in the resulting paper despite the fact that the paper contains substantial amounts of clay.
  • Figure 21 through 2S are charts showing the properties of the paper made by the process of this example which demonstrate the effectiveness of the complex silica-cationic starch bond. It should be noted that in the case of Figure 2M having to do with the roughness of the sheet, the paper was somewhat overdried at times so the conclusions as to this property which can be drawn from the chart may not be entirely valid.
  • the employment of the binder complex causes a mutual flocculation of the mineral matter, the cellulosic materials and the binder to produce highly improved retention and paper properties.
  • the binder permits the incorporation of substantial amounts of mineral filler with a cellulosic pulp to obtain the same or better properties than can be obtained in a sheet having a greater proportion of cellulosic fibers and a lesser amount of mineral filler when the binder of the invention is not employed.
  • Hand sheets were made up in a laboratory hand sheet former from various stocks made from bleached soft wood sulfate pulp with and without wollastonite as a filler, the stock including the cationic starch colloidai silicic acid complex binder to enhance the properties of the resultant paper.
  • the wollastonite used was in the form of acicular crystals between about 1 and 20 pm in diameter and having a length of about 15 times the diameter.
  • the colloidal silicic acid which was used was a silicic acid sol containing 15 percent of colloidal silicic acid having a surface area of approximately 500 m 2 /g.
  • the sol was alkali stabilized with a molar ratio of Si02:Naz0 of 40:1.
  • the cationic starch (C.S.) employed was the same starch.employed in Example I having a degree of substitution of 0.03.
  • the cationic starch was added in the form of a 4 percent (by weight) aqueous solution.
  • the colloidal silicic acid sol was added to the stock before the cationic starch.
  • the sol and cationic starch were added with the mineral to form a mineral-binder slurry which was then added to the cellulose.
  • the usual amount of water was added to make up a papermaking stock of the desired consistency of about 1% by weight solids. After the hand sheets were made they were pressed and dried under substantially identical conditions.
  • composition of the solids in each stock is set forth and the Z-strength (Scott Bond) was measured to provide an indication of the properties of the resulting sheet after pressing and drying.
  • Hand sheets were made up in a laboratory hand sheet former from various stocks made of 2.0 g of bleached soft wood sulfate pulp and 2.0 g of English china clay Grade C.
  • the china clay was dispersed in an alkali stabilized colloidal silicic acid sol diluted from 15% to 1.5% total solids by weight and the dispersion was added to the pulp in 500 ml of water in a laboratory disintegrator.
  • the hand sheets which were made were pressed and dried under substantially identical conditions.
  • Sheets of the following compositions were made, all of which included in addition to the 2 g of pulp and 2 g of clay the amounts and type of sol and the amounts of cationic starch indicated.
  • the properties of hand sheets produced are also set forth.
  • the silicic acid sol cationic starch complex greatly aids in the retention of clay, in many instances resulting in almost complete retention. Also, the above results show that maximum retention of the clay occurs when the colloidal silicic acid particles have a size range such that the surface area is between about 300 and 700 m 2 /g.
  • CS 2% cationic starch
  • suspensions 1, 2 and 4 were fed into a laboratory disintegrator containing 2.0 g of bleached softwood sulfate pulp in 500 ml of water and thoroughly agitated. Suspensions 3 and 5 were stored for 5 hours before mixing as above. Immediately after mixing, hand sheets were made, pressed and dried. The sheets had the following characteristics.
  • Example III As compared with the samples produced in Example III, while the tensile index is improved, the retention of the mineral filler is not as great as in that Example.
  • Hand sheets were made in a laboratory hand sheet former from various stocks as follows:
  • a slurry made of 2.0 g of Norwegian talc Grade IT Extra having a particle size ranging from about 1 to 5 pm, 8.0 g of water and 3.8 g of colloidal silicic acid (1.5% total solids, specific surface area 480 m 2 /g) was added to a stock consisting of 2.0 g of fully bleached soft wood sulfate pulp and 500 g of water in a laboratory disintegrator.
  • a sheet was made in a laboratory hand mold and was pressed and dried.
  • a reference sample was made where 4.0 g of the talc were added to 2.0 g of the pulp in 500 g of water, but no binder was added. (The amount of talc is larger to compensate for the poor retention so that the finished sheet will have approximately the same mineral content as the sheet made above with the binder).
  • the binder system of the present invention was added to different papermaking stocks to show that the invention is useful even in stocks containing considerable amounts of non-cellulosic fibers.
  • the colloidal silicic acid sol contained silica particles with a specific surface area of about 400 m 2 /g, and the silicic acid content of the sol was originally 15% by weight, but the sol was diluted with water to a silicic acid content of 1.5% by weight before it was used in the binder system.
  • the cationic starch used had a degree of substitution of 0.02 and was used as a 2% by weight solution.
  • a commercial trial run was made making a coated, off-set, supercalendered printing paper having a grammage of 85 g/m 2 .
  • the machine employed was a twin wire Beloit "Bel-Baie” machine having a capacity of about 10,000 kg/hour at a speed of about 600 m/min.
  • the coating was accomplished "on- line” with 10 g/m 2 of calcium carbonate applied to each side of the sheet.
  • the cellulosic fiber comprised 70% sulfate hardwood and 30% sulfate softwood pulp both of which were fully bleached.
  • the pH of the white water was about 8.5.
  • Fig. 4 is a flow diagram indicating the general operation which was employed in the run of this example employing incremental additions of the colloidal silicic acid in the process of the invention.
  • Mixing Tank No. 1 there was added in the form of an aqueous solution of colloidal silicic acid containing 15% by weight Si0 2 , in an amount equivalent to 1.7 kg of Si0 2 per metric ton of dry base sheet (prior to coating).
  • the colloidal silicic acid sol was stabilized with alkali with a molar ratio of S'0 2 :Na 2 O of 45:1.
  • the silicic acid had a particle size in the range of from about 5-7 nm and a surface area of approximately 500 m 2 /g.
  • the materials were thoroughly mixed and were conducted to Mixing Tank No. 2 where cationic starch was added to the stock, in an amount equal to 10.2 kg of cationic starch per metric ton of dry base sheet.
  • the cationic starch was prepared by treating potato starch with 3-chloro-2-hydroxypropyl- trimethyl-ammonium chloride to provide a degree of substitution (d.s.) in the starch of 0.03. It was dispersed in cold water at a concentration of about 4% by weight, heated for 30 minutes at about 90°C, diluted with cold water to a concentration of about 2% by weight and then added to Mixing Tank No. 2.
  • Fig. 5 graphically illustrates the effect of the addition of the colloidal silicic acid and cationic starch, as set forth above.
  • the left hand side of the chart shows the condition of the stock and the white water in the commercial run prior to the addition of the colloidal silicic acid and the cationic starch as outlined above.
  • the total solids in the stock at the former or head box is approximately 15.5 g/I, of which approximately 8.5 g/I is fiber and 7 g/I is ash.
  • the base sheet produced from this stock contained approximately 3 percent ash.
  • the white water in the commercial run before the addition of the colloidal silicic acid and cationic starch contained approximately 10.5 g/I of solids, 6.0 g/I ash, and 4.5 g/I fiber.
  • Test results showed that even though the finished base sheet made, as outlined above, had an increased amount of filler, i.e. from about 3 percent to about 15 percent which normally degrades the properties of the sheet, the additional filler did not materially decrease the strength properties or printing properties of the paper. To the contrary, certain properties were increased markedly.
  • Z-strength or internal bond strength measured by the Scott-Bond method increased by 85 percent at the 15 percent filler level as compared to the 3 percent filler level in the commercial runs.
  • the IGT Institut Voor Grafische Techniek, Amsterdam
  • surface picking resistance increased by 40 percent and the bursting strength increased by 40 percent.
  • Retention percentage is determined by dividing the difference between the concentration of total solids in the head box and the concentration of total solids in the white water by the concentration of total solids in the head box and multiplying by 100.
  • the percentage of retention was or 32%.
  • the percentage of retention increased to about 83% This high level of retention simplified white water clean-up and disposal.
  • Run 1 reflects the average operation of the machine of Example VIII in making coated, supercalendered printing paper over an extended period of time.
  • the cellulosic fiber comprised 70% sulfate hardwood and 30% sulfate softwood, both fully bleached. Normal amounts of broke were recycled.
  • the base sheet was coated with 10 g/m 2 of calcium carbonate per side.
  • Run 2 reflects the average operation of the machine of Example VIII over an extended period in making coated, supercalendered printing paper in which the same fiber was employed and normal amounts of broke were recycled in which the colloidal silicic acid employed was a 15% aqueous sol having the specifications set forth in Example VIII. It was added to Mixing Tank No. 1 at a level of 3.8 kg of Si0 2 per metric ton of dry base sheet. Cationic starch was added in Mixing Tank No. 2 at a level of 11.8 kg of cationic starch per metric ton of dry base sheet, the cationic starch having the specification as set forth in Example VIII and the method of addition was as set forth in Example VIII. No additions were made in Mixing Tank No. 3. The base sheet after drying was coated on each side with 10 g/m 2 of calcium carbonate.
  • Run 3 followed the procedure of Run 2 except that the addition of the silicic acid sol was added in two increments. There was added in Mixing Tank No. 1, 2.9 kg of Si0 2 per metric ton of dry base sheet. In Mixing Tank No. 2 the cationic starch was added at a level of 13.7 kg of cationic starch per metric ton of dry base sheet. In Mixing Tank No. 3 a second addition of the silicic acid sol was added at a level of 1.5 kg of Si0 2 per metric ton of dry base sheet.
  • the cationic starches used in this example were prepared from two different base material starches (A and B) to obtain the degrees of substitution mentioned in the table below.
  • All stocks for making the hand sheets were prepared by mixing 1.09 g china clay (English China Clay Grade C) with 2.72 g of a colloidal silicic acid sol (1.5% total solids and surface area 530 m 2 /g) and adding this slurry to a laboratory disintegrator containing 1.63 g of fully bleached softwood sulfate pulp in 500 ml water. After mixing the components in the disintegrator during 30 seconds, the relevant cationic starch was added. The mixing was then continued for about 15 seconds and then the stock was poured into the hand sheet former.
  • the tensile index of the different sheets is graphically shown as a function ot the amount of starch added (calculated as a weight percentage of the sum of the filler and fiber contents) in Figure 6 which clearly shows that a lower degree of substitution (d.s.) necessitates a larger amount of starch to bring about the maximum strength (tensile index).
  • d.s. degree of substitution
  • starch A having 0.033 d.s. gives the maximum strength at about 3.5% addition
  • starch A having 0.020 d.s. gives the maximum strength at about 4.3% addition.
  • starch B which at 0.047 d.s. gives the best strength at about 4.2% addition and at 0.026 d.s. gives the best strength at about 4.8%.
  • This Example concerns the applicability of the invention in producing light-weight fine paper.
  • the binder complex of the invention makes it possible to add substantial amounts of expanded perlite and still obtain the same or even better properties of the paper product.
  • Figure 8A shows that the binder of the present invention substantially improved the modulus of elasticity compared to the known additive (run A) both in the machine direction (curve M.D.) and in the cross direction (curve C.D.).
  • the modulus of elasticity in runs C and D where the expanded perlite had been added was higher than in reference run A and was still at about the same level in run E as in run A in spite of the complete replacement of the chalk filler with the expanded perlite filler.
  • Figures 8B, 8C, 8E and 8F show that the same good trend is obtained with regard to the tensile index, the tensile energy absorption, the stiffness and the surface picking resistance (expressed as Dennison wax pick).
  • Figure 8D shows the decrease of density obtained by the replacement of the chalk mineral with the expanded perlite mineral.
  • Figure 8G shows the Bendtsen roughness number (SCAN P-21) at different density levels of paper products.
  • the curves for the reference paper (run A) and for run B (chalk as the sole mineral using the binder complex of the invention) were so close to each other that they had to be drawn as a single curve in the chart.
  • the inventive binder complex and the expanded perlite filler in high proportions made it possible to obtain smooth papers (low Bendtsen numbers) at low densities.
  • This Example shows that the invention is useful for producing special papers from stocks which contain both cellulosic and non-cellulosic fibers and which are extended with mineral fillers, specially good results being obtained when using low-density mineral fillers as extenders.
  • All the stocks contained 50% by weight of fully bleached softwood sulfate pulp, 20% by weight of mineral fibers (mineral wool fibers), 1.43% by weight of colloidal silicic acid sol (specific surface area about 500 m l /g) and 3.57% by weight of a cationic starch (degree of substitution 0.03).
  • the remaining 25% by weight of the stock consisted of either chalk or expanded perlite or a mixture thereof. All the percentages are calculated as dry solids and are based on the stock as a whole.
  • the silicic acid sol was used as a 1.5% solution and the cationic starch as a 1% solution.
  • the mineral filler (solely chalk and solely expanded perlite, respectively) was initially slurried in the silicic acid sol solution.
  • the mineral fillers (15% chalk and 10% expanded perlite) was initially mixed and then slurried in the silicic acid sol solution.
  • the mineral-sol-slurry was added to the premixed mineral fiber-sulfate pulp in 500 ml water in a laboratory disintegrator. After 30 s mixing time in the disintegrator the different sheets were formed on the hand sheet former and pressed at a pressure of 5 kg/cm 2 . The properties of the dried papers will appear from the table of this example.
  • the samples A, B and C show that it is possible to replace some or all of the chalk filler with an expanded perlite filler to lower the density, still keeping the other properties at about the same level as with chalk as the sole mineral extender or filler. It is to be noted that the retention calculated on the ash content was almost 100% in all samples, which is high considering that the retention of the expanded perlite filler is low when the binder complex of the present invention is not used.
  • This Example concerns the clarification of white water from a twin wire papermaking machine making wood-free coated paper.
  • White water samples were taken from the normal production run of the papermaking machine and were analyzed for solids content and kinds of solids.
  • the solids content was 7 grams/liter, and about 60% by weight of the solids consisted of china clay and chalk.
  • the cationic starch having a degree of substitution of 0.033 was used as a solution containing 4% by weight of the starch.
  • the colloidal silicic acid sol had a particle size of about 6 nm, a specific surface area of about 500 m 2 /g and a silicic acid concentration of 15% by weight.
  • This Example concerns the clarification of white water from a combined board and printing paper mill.
  • White water samples were taken from the mixed white waters from the mill and were analyzed for solids content and types of solids.
  • the solids content was 1.1 g/I and about 25% of the solids was pigment (mainly china clay).
  • a number of tests were made to determine the settling rates and the turbidity of the white water when treated with PERCOL@ 1697 (a typical example of agents for white water treatment) and with a binder according to the present invention comprising a silicic acid sol and a cationic starch.
  • the settling rates were determined by using a graded conical funnel having a diameter of 110 mm at the wide top end and a height of 400 mm and being graded. To 1200 ml samples of the white water there were added a silicic acid sol and a cationic starch under vigorous agitation. The samples were then poured into the graded funnel and left standing while the interface between an almost clear upper phase and a lower turbid phase gradually sank. The time for this interface to pass every 50 or 100 ml mark on the funnel was noted, and the settling rates calculated were plotted in Figure 7.
  • the almost clear upper phase was nearly free from flocks but was opalescent due to various amounts of fines and pigment particles. For this reason, the turbidity was measured, using a sample taken from the top of the funnel well above the interface 15 minutes after pouring the sample into the funnel. Samples from the funnel were also taken for determining the solids content of the white water after this settling time.
  • the turbidity was measured according to Swedish Standard SIS in a turbidity tester (Hach model 2100 A) giving the result in Formazin Turbidity Units (FTU). The lower the FTU figures, the better is the clarification.
  • FTU Formazin Turbidity Units
  • the test results are tabulated below together with the solids content of the clear phase and the settling rates.
  • the settling rates given in the table were calculated from the straight lines between the levels 200 ml and 600 ml in Figure 7.
  • a comparative test series was made using PERCOL@ 1697 as an additive (0.5% solution). To 1200 ml white water additions of 2 ml, 1 ml, 0.8 ml, 0.6 ml and 0.4 ml, respectively, of the 0.5% solution of PERCOL® 1697 were added, and then the settling times were determined. With this additive the 0.6 ml addition gave the best result (Sample B shown in Figure 7).
  • the weight ratio (R) of starch:Si0 2 was 1.5:1 for sample C and 2.0:1 for sample D, and in both cases the silicic acid sol used was an alkali stabilized silicic acid sol having a specific surface area of about 500 m 2 /g and the original concentration of 15%, although diluted to 1.5% concentration before use.
  • a colloidal silicic acid-cationic starch binder complex especially a complex in which the colloidal silicic acid component is added incrementally, a portion being added after the initial agglomerate is formed, makes possible substantial economics in the papermaking process as well as a unique paper product.
  • the strength characteristics can be improved to the point that mechanical pulps can be substituted in substantial proportions for chemical pulps, while still maintaining the strength and other properties desired.
  • the grammage of the sheet may be reduced while maintaining the desired properties.
  • a mineral filler may be employed in much larger proportions than heretofore used while maintaining or even improving the characteristics and properties of the sheet. Or in the alternative the properties of a sheet containing filler may be enhanced.
  • the binder system results in increased retention of both minerals and fines so that white water problems are minimized.
  • the system disclosed herein can also be used to advantage to agglomerate solids in white water to facilitate its disposal or reuse.
  • the binder complex makes it possible to reduce the solids content of the white water and thus to reduce the environmental problems also in papermills not using the binder complex of this invention as an additive to the stock per se.
  • the binder system thus improves the recovery of solids in the white water and improves the economy of the entire papermaking process.

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  • Chemical & Material Sciences (AREA)
  • Dispersion Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Paper (AREA)
EP81850084A 1980-05-28 1981-05-18 Papermaking Expired EP0041056B1 (en)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
SE8003948 1980-05-28
SE8003948A SE432951B (sv) 1980-05-28 1980-05-28 Pappersprodukt innehallande cellulosafibrer och ett bindemedelssystem som omfattar kolloidal kiselsyra och katjonisk sterkelse samt forfarande for framstellning av pappersprodukten
US238645 1981-02-26
US06/238,645 US4385961A (en) 1981-02-26 1981-02-26 Papermaking

Publications (2)

Publication Number Publication Date
EP0041056A1 EP0041056A1 (en) 1981-12-02
EP0041056B1 true EP0041056B1 (en) 1984-08-08

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EP81850084A Expired EP0041056B1 (en) 1980-05-28 1981-05-18 Papermaking

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EP (1) EP0041056B1 (sv)
AR (1) AR231848A1 (sv)
AT (1) ATE8916T1 (sv)
AU (1) AU546999B2 (sv)
BR (1) BR8103345A (sv)
DE (1) DE3165370D1 (sv)
ES (1) ES502531A0 (sv)
FI (1) FI68283C (sv)
MX (1) MX158106A (sv)
NO (1) NO161334C (sv)
NZ (1) NZ197223A (sv)
SU (1) SU1228793A3 (sv)

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DE3837746C1 (sv) * 1988-11-07 1990-03-29 Manfred Zeuner

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SE8107078L (sv) * 1981-11-27 1983-05-28 Eka Ab Forfarande for papperstillverkning
US4810301A (en) * 1983-07-22 1989-03-07 Seiko Kagaku Kogyo Co., Ltd. Composition for sizing agent and process for using the same composition
JPS61234927A (ja) * 1984-09-25 1986-10-20 Seiko Kagaku Kogyo Co Ltd 置換コハク酸無水物の水性分散液及びその製造方法
GB8531558D0 (en) * 1985-12-21 1986-02-05 Wiggins Teape Group Ltd Loaded paper
US4750974A (en) * 1986-02-24 1988-06-14 Nalco Chemical Company Papermaking aid
JPS6328999A (ja) * 1986-07-22 1988-02-06 星光化学工業株式会社 製紙方法
SE8701252D0 (sv) * 1987-03-03 1987-03-25 Eka Nobel Ab Sett vid framstellning av papper
JPH0192498A (ja) * 1987-10-02 1989-04-11 Hokuetsu Paper Mills Ltd 中性紙の製造方法
US4946557A (en) * 1988-03-08 1990-08-07 Eka Nobel Ab Process for the production of paper
SE461156B (sv) * 1988-05-25 1990-01-15 Eka Nobel Ab Saett foer framstaellning av papper varvid formning och avvattning aeger rum i naervaro av en aluminiumfoerening, ett katjoniskt retentionsmedel och en polymer kiselsyra
SE500367C2 (sv) * 1989-11-09 1994-06-13 Eka Nobel Ab Silikasoler och förfarande för framställning av papper
SE500387C2 (sv) * 1989-11-09 1994-06-13 Eka Nobel Ab Silikasoler, förfarande för framställning av silikasoler samt användning av solerna i pappersframställning
DK0512038T3 (da) * 1990-01-22 1995-07-24 Exxon Chemical Patents Inc Skumreduktion ved papirfremstilling
SE9003954L (sv) * 1990-12-11 1992-06-12 Eka Nobel Ab Saett foer framstaellning av ark- eller banformiga cellulosafiberinnehaallande produkter
SE502192C2 (sv) * 1990-12-11 1995-09-11 Eka Nobel Ab Upplösningsförfarande avsett för en lösning innehållande höghaltjoniserad stärkelse
TR24973A (tr) * 1991-02-05 1992-09-01 Exxon Chemical Patents Inc KAGIT IMALINDE KÖPüKLENMENIN AZALTILMASI
US5149370A (en) * 1991-10-21 1992-09-22 Halliburton Company Well cement compositions having improved properties and methods
US5368690A (en) * 1992-12-23 1994-11-29 National Starch And Chemical Investment Holding Corporation Method of papermaking using crosslinked cationic/amphoteric starches
EP0776397B1 (en) * 1994-08-16 2000-10-25 Chemisolv Limited Process of improving paper strength
US5571494A (en) * 1995-01-20 1996-11-05 J. M. Huber Corporation Temperature-activated polysilicic acids
FR2732368B1 (fr) * 1995-03-31 1997-06-06 Roquette Freres Nouveau procede de fabrication de papier
US5620629A (en) * 1995-09-28 1997-04-15 Nalco Chemical Company Colloidal silica/polyelectrolyte blends for natural water clarification
FR2743810B1 (fr) 1996-01-23 1998-04-10 Roquette Freres Polysaccharides cationiques modifies, compositions pour le collage les contenant et procedes pour le collage de structures planes mettant en oeuvre ces compositions
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US6355141B1 (en) 1998-04-23 2002-03-12 Akzo Nobel N.V. Process for the production of paper
FR2794479B1 (fr) 1999-06-04 2001-09-21 Roquette Freres Composition et procede pour la fabrication de structures planes, en particulier du papier ou du carton
GB0030132D0 (en) * 2000-12-09 2001-01-24 Arjo Wiggins Fine Papers Ltd Security paper
FI121119B (sv) † 2003-04-15 2010-07-15 Kemira Oyj Förfarande för framställning av papper
GB0702248D0 (en) 2007-02-05 2007-03-14 Ciba Sc Holding Ag Manufacture of Filled Paper
GB0702249D0 (en) 2007-02-05 2007-03-14 Ciba Sc Holding Ag Manufacture of paper or paperboard
DE102008000811A1 (de) 2007-03-29 2008-10-09 Basf Se Verfahren zur Herstellung von Papier
US8440768B2 (en) 2008-06-19 2013-05-14 Buckman Laboratories International, Inc. Low amidine content polyvinylamine, compositions containing same and methods
CN108130801B (zh) 2013-12-18 2020-11-24 艺康美国股份有限公司 生产用于造纸的活化胶态二氧化硅的方法
ES2948357T3 (es) 2015-08-06 2023-09-11 Solenis Technologies Cayman Lp Procedimiento para la fabricación de papel
US11846072B2 (en) 2016-04-05 2023-12-19 Fiberlean Technologies Limited Process of making paper and paperboard products
CN109072551B (zh) 2016-04-05 2020-02-04 菲博林科技有限公司 纸和纸板产品

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DE3837746C1 (sv) * 1988-11-07 1990-03-29 Manfred Zeuner

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ES8304247A1 (es) 1983-02-16
AR231848A1 (es) 1985-03-29
SU1228793A3 (ru) 1986-04-30
ES502531A0 (es) 1983-02-16
FI68283B (fi) 1985-04-30
NO161334B (no) 1989-04-24
NO161334C (no) 1989-08-02
AU546999B2 (en) 1985-10-03
BR8103345A (pt) 1982-02-16
NZ197223A (en) 1984-05-31
EP0041056A1 (en) 1981-12-02
FI811628L (fi) 1981-11-29
MX158106A (es) 1989-01-09
DE3165370D1 (en) 1984-09-13
AU7051481A (en) 1981-12-03
FI68283C (fi) 1985-08-12
NO811811L (no) 1981-11-30
ATE8916T1 (de) 1984-08-15

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