CA2620089A1 - Stevensite- and/or cerolite-containing adsorbents for binding interfering substances during the manufacturing of paper - Google Patents
Stevensite- and/or cerolite-containing adsorbents for binding interfering substances during the manufacturing of paper Download PDFInfo
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- CA2620089A1 CA2620089A1 CA002620089A CA2620089A CA2620089A1 CA 2620089 A1 CA2620089 A1 CA 2620089A1 CA 002620089 A CA002620089 A CA 002620089A CA 2620089 A CA2620089 A CA 2620089A CA 2620089 A1 CA2620089 A1 CA 2620089A1
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- Prior art keywords
- stevensite
- cerolite
- containing component
- interfering substances
- paper
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- 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
- D21H21/02—Agents for preventing deposition on the paper mill equipment, e.g. pitch or slime control
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- 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
Abstract
The invention relates to a method for binding interfering substance during the manufacturing of paper, comprising the following steps: (a) preparing at least one stevensite- and/or cerolite-containing constituent; (b) preparing a paper pulp or fibrous material; (c) adding the at least one stevensite- and/or cerolite-containing constituent to the paper pulp or fibrous material, and;
(d) enabling the binding of interfering substance to the at least one stevensite- and/or cerolite-containing constituent in the paper pulp or fibrous material suspension.
(d) enabling the binding of interfering substance to the at least one stevensite- and/or cerolite-containing constituent in the paper pulp or fibrous material suspension.
Description
~... ~ CA 02620089 2008-02-22 August 18, 2006 Sud-Chemie AG
Lenbachplatz 6 80333 Munich 4465-X-23.792 STEVENSITE- AND/OR CEROLITE-CONTAINING
ADSORBENTS FOR BINDING INTERFERING SUBSTANCES
DURING THE MANUFACTURING OF PAPER
Description The present invention relates to the use of stevensite- and/or cerolite-containing materials in the control of interfering substances in papermaking.
The control of interfering substances in papermaking is becoming increasingly important. The problem also arises because water resulting during papermaking is circulated, interfering substances gradually accumulating. These interfering substances can thus lead to a very wide range of product defects, such as, for example, to the formation of deposits on the rolls of the paper machine, to blocking of the wires, etc. These effects lead to interruptions during paper production. In order to minimize the number of production stops, it is desirable to bind the interfering substances resulting in the circulation water by using polymers or adsorbents in the stock circulation itself.
Most relevant interfering substances are negatively charged.
They are, for example, humic acids, tree resin colloids, lignin derivatives and ligninsulfonates which are introduced into the paper circulation from the fibers. In addition, there are interfering substances which are introduced into the paper machine through recycling of broke. This broke is typically redispersed and introduced into the paper machine. The ingredients and auxiliaries present therein are thus completely recycled to the circulation. In addition, for example, carboxymethylcelluloses, polyacrylates, polyphosphonates and silicates are introduced thereby. Further charged interfering substances are the latices which are used in paper coating.
These have a strong tendency toward agglomeration, the agglomerates being deposited as tacky, white residues on the paper machine (so-called white pitch).
The prior art extensively describes the discharge of tacky substances (so-called "stickies") as a result of the use of talc. Thus, according to P. Biza, E. Gaksch and P. Kaiser, "Verbesserter Austrag von Stickys durch den Einsatz von Talkum [Improved discharge of stickies by the use of talc]", Wochenblatt fur Papierfabrikation 11/12 (2002) page 759 et seq., the action of talc for reducing tacky deposits was documented no later than the beginning of the last century. Virtually all known natural and synthetic tacky substances are hydrophobic.
Talc is most suitable for binding the stickies because it has a naturally hydrophobic surface which enables it easily to become adsorbed onto adhesive surfaces and to make them less tacky by coating.
Furthermore, the use of montmorillonites, such as bentonite, for controlling interfering substances in the paper pulp is described, for example, in US 5,368,962. The alkali treatment of bentonite is also discussed as a possibility.
US 4,964,955 likewise describes a process for reducing interfering substances during papermaking. A particulate composition containing (a) a water-soluble cationic polymer which is applied to (b) a substantially water-insoluble particulate substrate is present therein for binding interfering substances. The polymer should be sufficiently electropositive so that the particulate composition has a zeta potential of at least about +30 mV. The polymer is preferably a poly(dialkyldiallylammonium halide). The substrate is, for example, a phyllosilicate mineral.
In a similar manner, EP 0 760 406 A2 relates to a combination of a poly(dadmac/acrylamide) and a bentonite in the binding of interfering substances.
GB 2 297 334 A in turn discloses the use of a smectitic clay for controlling interfering substances, the smectitic clay being modified as follows: monovalent exchangeable cations are present in an equivalent ionic fraction in the range from 0.20 to 0.60;
a first type of bivalent exchangeable cations is present in an equivalent ionic fraction in the range from 0.40 to 0.80; and a second type of bivalent exchangeable cation is present in an equivalent ionic fraction in the range from 0.00 to 0.20, the first type of bivalent exchangeable cations comprising calcium and the second type of bivalent exchangeable cations comprising magnesium.
Many of the compositions used in the prior art for binding interfering substances are very expensive and not optimally suitable for certain compositions of interfering substances.
There is therefore constant need for compositions for binding interfering substances in papermaking.
It was therefore an object of the present invention to provide an improved method for binding interfering substances in papermaking, which method avoids the disadvantages of the prior art. It was also an object to permit the use of a composition which is simple and economical to prepare and to provide a high degree of binding of interfering substances, including hydrophobic fractions.
This object is achieved by the method as claimed in claim 1.
Thus, within the scope of the present invention, it was surprisingly found that outstanding control of interfering substances is made possible by the use of stevensite- and/or cerolite-containing components in a method for papermaking. The stevensite- and/or cerolite-containing components bind or sorb interfering substances, including hydrophobic fractions thereof, to a surprisingly high extent. These components are therefore also regarded as sorbents or adsorbents or absorbents, these terms being used here synonymously for simplicity.
In the context of the present invention, interfering substances are understood as meaning both tacky substances, also referred to in the literature as "stickies", and so-called pitch, i.e.
primarily tree resin components. Reference may be made here to the statements on the interfering substances made in the introduction to the description. A detailed list of the pitch and stickies constituents is to be found, for example, in WO 01/09424, on pages 1 and 2, and the disclosure there is hereby expressly incorporated in the present description by reference.
A particularly preferred aspect relates to the use of at least one stevensite- and/or cerolite-containing component for binding or removing hydrophobic interfering substances in a method for papermaking.
According to a first aspect according to the invention, the component used contains stevensite or a stevensite phase.
Lenbachplatz 6 80333 Munich 4465-X-23.792 STEVENSITE- AND/OR CEROLITE-CONTAINING
ADSORBENTS FOR BINDING INTERFERING SUBSTANCES
DURING THE MANUFACTURING OF PAPER
Description The present invention relates to the use of stevensite- and/or cerolite-containing materials in the control of interfering substances in papermaking.
The control of interfering substances in papermaking is becoming increasingly important. The problem also arises because water resulting during papermaking is circulated, interfering substances gradually accumulating. These interfering substances can thus lead to a very wide range of product defects, such as, for example, to the formation of deposits on the rolls of the paper machine, to blocking of the wires, etc. These effects lead to interruptions during paper production. In order to minimize the number of production stops, it is desirable to bind the interfering substances resulting in the circulation water by using polymers or adsorbents in the stock circulation itself.
Most relevant interfering substances are negatively charged.
They are, for example, humic acids, tree resin colloids, lignin derivatives and ligninsulfonates which are introduced into the paper circulation from the fibers. In addition, there are interfering substances which are introduced into the paper machine through recycling of broke. This broke is typically redispersed and introduced into the paper machine. The ingredients and auxiliaries present therein are thus completely recycled to the circulation. In addition, for example, carboxymethylcelluloses, polyacrylates, polyphosphonates and silicates are introduced thereby. Further charged interfering substances are the latices which are used in paper coating.
These have a strong tendency toward agglomeration, the agglomerates being deposited as tacky, white residues on the paper machine (so-called white pitch).
The prior art extensively describes the discharge of tacky substances (so-called "stickies") as a result of the use of talc. Thus, according to P. Biza, E. Gaksch and P. Kaiser, "Verbesserter Austrag von Stickys durch den Einsatz von Talkum [Improved discharge of stickies by the use of talc]", Wochenblatt fur Papierfabrikation 11/12 (2002) page 759 et seq., the action of talc for reducing tacky deposits was documented no later than the beginning of the last century. Virtually all known natural and synthetic tacky substances are hydrophobic.
Talc is most suitable for binding the stickies because it has a naturally hydrophobic surface which enables it easily to become adsorbed onto adhesive surfaces and to make them less tacky by coating.
Furthermore, the use of montmorillonites, such as bentonite, for controlling interfering substances in the paper pulp is described, for example, in US 5,368,962. The alkali treatment of bentonite is also discussed as a possibility.
US 4,964,955 likewise describes a process for reducing interfering substances during papermaking. A particulate composition containing (a) a water-soluble cationic polymer which is applied to (b) a substantially water-insoluble particulate substrate is present therein for binding interfering substances. The polymer should be sufficiently electropositive so that the particulate composition has a zeta potential of at least about +30 mV. The polymer is preferably a poly(dialkyldiallylammonium halide). The substrate is, for example, a phyllosilicate mineral.
In a similar manner, EP 0 760 406 A2 relates to a combination of a poly(dadmac/acrylamide) and a bentonite in the binding of interfering substances.
GB 2 297 334 A in turn discloses the use of a smectitic clay for controlling interfering substances, the smectitic clay being modified as follows: monovalent exchangeable cations are present in an equivalent ionic fraction in the range from 0.20 to 0.60;
a first type of bivalent exchangeable cations is present in an equivalent ionic fraction in the range from 0.40 to 0.80; and a second type of bivalent exchangeable cation is present in an equivalent ionic fraction in the range from 0.00 to 0.20, the first type of bivalent exchangeable cations comprising calcium and the second type of bivalent exchangeable cations comprising magnesium.
Many of the compositions used in the prior art for binding interfering substances are very expensive and not optimally suitable for certain compositions of interfering substances.
There is therefore constant need for compositions for binding interfering substances in papermaking.
It was therefore an object of the present invention to provide an improved method for binding interfering substances in papermaking, which method avoids the disadvantages of the prior art. It was also an object to permit the use of a composition which is simple and economical to prepare and to provide a high degree of binding of interfering substances, including hydrophobic fractions.
This object is achieved by the method as claimed in claim 1.
Thus, within the scope of the present invention, it was surprisingly found that outstanding control of interfering substances is made possible by the use of stevensite- and/or cerolite-containing components in a method for papermaking. The stevensite- and/or cerolite-containing components bind or sorb interfering substances, including hydrophobic fractions thereof, to a surprisingly high extent. These components are therefore also regarded as sorbents or adsorbents or absorbents, these terms being used here synonymously for simplicity.
In the context of the present invention, interfering substances are understood as meaning both tacky substances, also referred to in the literature as "stickies", and so-called pitch, i.e.
primarily tree resin components. Reference may be made here to the statements on the interfering substances made in the introduction to the description. A detailed list of the pitch and stickies constituents is to be found, for example, in WO 01/09424, on pages 1 and 2, and the disclosure there is hereby expressly incorporated in the present description by reference.
A particularly preferred aspect relates to the use of at least one stevensite- and/or cerolite-containing component for binding or removing hydrophobic interfering substances in a method for papermaking.
According to a first aspect according to the invention, the component used contains stevensite or a stevensite phase.
What is to be understood by stevensite is familiar to a person skilled in the art. More detailed characterization of stevensite is to be found, for example, in J.L. Martin de Vidales et al., Clay Minerals (1991) 26, pages 329-342, and in G.B. Brindley et al., Mineralogical Magazine, 1977, vol. 41, pages 443-452, to which express reference may be made. The determination of stevensite can be carried out as described there. What is characteristic is the diffraction peak at lattice spacing (basal spacing) 10 A, the position of which shows a substantial shift at different humidities. According to a first aspect of the invention, a material which has the characteristic diffraction peak at the lattice spacing (basal spacing) 10 A according to Brindley et al (loc. cit.) preferably also the peak shift described there at different humidities or a treatment with ethylene glycol (see below) is therefore regarded as stevensite or a stevensite-containing component. Also characteristic is the spacing in the vicinity of 17 A on treatment with ethylene glycol. Here, reference is expressly made to the powder X-ray diffraction patterns for stevensite and to related parts of the text, given by G.B. Brindley et al. (loc. cit.).
According to the invention, the position of the diffraction peak at the lattice spacing of about 10 A therefore changes in a characteristic manner in the stevensite used in the mycotoxin adsorbent or in the stevensite-containing component at different humidities or on treatment with ethylene glycol according to fig. 2 of the literature reference Brindley et al. (loc. cit.). In this way, the stevensite used therefore also differs, for example, from pure cerolite.
The expression "stevensite" is intended here also to include stevensite-containing components for the sake of simplicity.
The term "stevensite-containing component" is intended to express the fact that, according to the invention, components which also contain further constituents in addition to stevensite can also be used according to the invention. For example, many commercially available stevensite products contain not only stevensite but also different amounts of accompanying minerals. Moreover, mixtures of stevensite with other constituents, such as, for example, other mineral constituents, in particular phyllosilicates, are also conceivable.
In an embodiment according to the invention, at least one stevensite- and/or cerolite-containing component which consists substantially or completely of stevensite or of at least one stevensite-containing component is used.
In a further aspect according to the invention, the component used contains cerolite or a cerolite phase.
What is to be understood by cerolite is familiar to a person skilled in the art and need not be explained in more detail here. For example, reference may also be made here to Brindley et al. (loc. cit.). The determination of cerolite can be carried out as described there. The chemical analysis of cerolite gives a composition close to R3Si4O10(OH)2=nH2O, where R is mainly Mg and n is from about 0.8 to 1.2. What is characteristic is the diffraction peak at lattice spacing (basal spacing) 10 A, the position of which shows no expansion at different humidities and no thermal contraction up to 500 C. Here, express reference is made to the powder X-ray diffraction patterns for cerolite and the related parts of the text, which are given by G.B. Brindley et al. (loc.
cit.) in fig. 2 Brindley et al. (loc. cit.) in fig. 2. In a possible embodiment according to the invention, the stevensite or the at least one stevensite-containing component is partly or completely replaced by cerolite or at least one cerolite-containing component in the composition according to the invention.
The expression "cerolite" is intended here also to include cerolite-containing components for the sake of simplicity.
The term "cerolite-containing component" is intended to express the fact that, according to the invention, it is also possible to use components which also contain further constituents in addition to cerolite. For example, many commercially available cerolite products contain not only cerolite but also different amounts of accompanying minerals.
Moreover, mixtures of cerolite with other constituents, such as, for example, other mineral constituents, in particular phyllosilicates, are also conceivable.
In an embodiment according to the invention, at least one stevensite- and/or cerolite-containing component which substantially or completely consists of cerolite or of at least one cerolite-containing component is used.
In a further aspect according to the invention, the component used contains both stevensite or a stevensite phase and cerolite or a cerolite phase. It was found that such stevensite- and cerolite-containing components have particularly good properties with regard to binding interfering substances.
According to a preferred embodiment, the stevensite- and/or cerolite-containing component used contains at least 10% by weight, preferably at least 50% by weight, in particular at least 75% by weight, particularly preferably at least 90% by weight, especially preferably at least 95% by weight, of stevensite and/or cerolite. Thus, it was surprisingly found that particularly good binding of interfering substances results if stevensite and/or cerolite represents the main phase mineralogically in the components used according to the invention.
Within the scope of the present invention, it was furthermore found that in particular those stevensite- and/or cerolite-containing components which have a magnesium oxide content of at least 15% by weight, in particular at least 17% by weight, more preferably at least 20% by weight, are suitable.
Corresponding materials are commercially available.
Furthermore, it is preferable if the magnesium oxide content of the stevensite- and/or cerolite-containing components used, in particular of the stevensite or of the stevensite-containing component, is not more than 40% by weight, in particular not more than 35% by weight, in many cases more preferably not more than 32% by weight.
The content of magnesium oxide is also determinative for the exact formation of the layer structure of the material. It is assumed, without limiting the invention to the correctness of this assumption, to the layer structure of the material used according to the invention, in particular of the stevensite, provides a particularly advantageous porosimetry and particularly efficient surfaces for the adsorption of a multiplicity of different interfering substances.
In an embodiment according to the invention, in particular in the case of components having a high proportion of stevensite, the BET surface area (measured according to DIN 66131, cf. method section) is preferably at least 60 m2/g, in particular at least 80 m2/g, especially at least 100 m2/g. These high BET surface areas evidently provide even more efficient adsorption for some interfering substances.
It was furthermore found that in particular those components which have a cation exchange capacity (CEC) of less than 40 meq/100 g, in particular less than 35 meq/100 g, , CA 02620089 2008-02-22 particularly preferably less than 30 meq/100 g, give particularly good results. The CEC can be determined as stated in the method section below.
According to a further preferred embodiment, the stevensite-and/or cerolite-containing components used are those whose CEC is at least 2 meq/100 g, preferably at least 5 meq/100 g, in particular at least 10 meq/100 g, more preferably at least 15 meq/100 g.
"cation exchange capacity" (CEC) is understood as meaning the sum of all exchangeable cations, stated in meq/100 g and determined according to the CEC analysis method, as explained below before the example section (determination of the cation exchange capacity). The cation exchange capacity thus comprises, for example, the sum of all exchangeable divalent and monovalent cations, such as calcium, magnesium, sodium, lithium and potassium ions. For the determination of the cation exchange capacity, the stevensite- and/or cerolite-containing component is treated with an ammonium chloride solution. Owing to the high affinity of the ammonium ions for the stevensite- and/or cerolite-containing component, virtually all exchangeable cations are exchanged by ammonium ions. After separating off and washing, the nitrogen content of the stevensite- and/or cerolite-containing components is determined and the content of ammonium ions is calculated therefrom.
As stated above, the stevensite- and/or cerolite-containing components used according to the invention surprisingly have a substantially better action in the control of interfering substances than the conventionally used products, such as, for example, talc.
Compared with other agents, such as, for example, conventional bentonites, there is a further advantage in that stevensite-and/or cerolite-containing components can as a rule be processed to give (aqueous) slurries or suspensions having a much higher solids content without the processing and metering being adversely affected by an excessively high viscosity of the slurry or suspension. Thus, in many paper mills in practice, the raw materials, including the agents or components used for binding interfering substances, are metered in in liquid form.
The higher the solids content of the slurry or suspension to be metered the smaller is the amount to be metered or to be prepared and to be transported.
In the present invention, it was also surprisingly found that the action of the stevensite- and/or cerolite-containing components with regard to binding interfering substances can be even further increased if they are activated. Particularly in the case of stevensite-containing components, the activation was found to have a good effect. According to the invention, activation is understood here as meaning an at least partial exchange of the intermediate layer cations, in particular of the divalent or polyvalent intermediate layer cations of stevensite in the stevensite-containing component, for monovalent cations.
The exchanged monovalent cations may be in particular H+ or one or more alkali metal cations. Preferred forms of the activation are activations using acid or alkali. A preferred, nonlimiting example of an alkali activation is the activation with sodium carbonate. For this purpose, for example, the pit-moist clay, which usually has water contents of from 25 to 40% by weight of moisture, is mixed with up to 5% by weight, in particular up to 4% by weight, of sodium carbonate, potassium carbonate or other salts of alkali metal ions, such as, for example, phosphates or citrates, based on anhydrous clay, and, if appropriate, also extruded. Drying and milling are then effected.
Acid activation of the stevensite-containing component can generally be carried out by a treatment with one or more acids.
For this purpose, the component is brought into contact with at least one inorganic and/or organic acid. In principle, any method for the acid activation of clays which is known to the person skilled in the art can be used. In one possible embodiment according to the invention, it is not necessary to wash out the excess acid and the salts forming during the activation. Rather, after addition of the acid, as is usual in the acid activation, no wash step is carried out but the treated component is dried and, if appropriate, milled to the desired particle size.
The acid activation can be effected, for example, with acids in solid form or with an acid solution. Thus, in one embodiment, the activation of the component is carried out in the aqueous phase. For this purpose, the acid in the form of an aqueous solution is brought into contact with the stevensite-containing component. For example it is possible here to adopt a procedure in which the stevensite-containing component, which is preferably provided in the form of a powder, is first suspended in water. The acid, for example in concentrated form, is then added. The stevensite-containing component can, however, also be suspended directly in an aqueous solution of the acid, or the aqueous solution of the acid can be added to the stevensite-containing component. According to an advantageous embodiment, the aqueous acid solution can, for example, be sprayed onto a preferably crushed or pulverulent stevensite-containing component, the amount of water preferably being chosen to be as low as possible. For example, a concentrated acid or acid solution is used here. When spraying on small amounts of acid, often only a superficial activation takes place, also referred to as "surface modification". The amount of acid can preferably be chosen to be from 1 to 10% by weight, particularly preferably from 2 to 6% by weight, of a strong acid, in particular of a mineral acid, such as sulfuric acid, based on the anhydrous stevensite-containing component (absolutely dry). If required, excess water can be evaporated off and the activated stevensite-containing component can, if appropriate, be milled to the desired fineness. As already mentioned above, in an embodiment of the method according to the invention, no wash step is required. After addition of the aqueous solution of the acid, drying is only effected, if required, until the desired moisture content is reached. In general, the water content of the activated stevensite-containing component obtained is adjusted to a proportion of less than 20% by weight, preferably less than 10% by weight.
For the activation described above with an aqueous solution of an acid or of a concentrated acid, the acid can be arbitrarily chosen. It is possible to use both mineral acids and organic acids or mixtures of the above acids. It is possible to use customary mineral acids, such as hydrochloric acid, phosphoric acid or sulfuric acid, sulfuric acid being preferred. It is possible to use concentrated or dilute acids or acid solutions.
Organic acids used may be, for example, citric acid or oxalic acid.
In a particularly preferred embodiment according to the invention, the stevensite- and/or cerolite-containing component has, based on the CEC, a proportion of at least 50%, in particular at least 80%, of monovalent cations, such as H+, Na+, K+ and/or Li+. This proportion can be reached or increased, for example, by activation of the component with an acid or an alkali metal salt (e.g. sodium carbonate). At least 90%, in particular about 100%, of monovalent cations, based on the CEC
of the stevensite- and/or cerolite-containing component, are particularly preferred.
The method according to the invention for the use of the stevensite- and/or cerolite-containing components described herein can be used generally in all processes for paper or cardboard production. Accordingly, the expressions paper pulp and fiber suspension are intended generally to include all compositions or streams which contain interfering substances and are used in the production of paper, cardboard, other fibrous materials or the like. Otherwise, the expressions "(paper) pulp"
and "fiber suspension" are familiar to a person skilled in the art and need not be explained in more detail here.
In a preferred embodiment according to the invention, the pulp or the fiber suspension is a suspension containing (fine) groundwood. Groundwood is in general finely digested (finely ground wood, generally without further chemical or thermal treatment). The groundwood suspension is either used directly after comminution or subjected to a peroxide bleach, so-called peroxide-bleached groundwood then forming. It has surprisingly been found that the stevensite- and/or cerolite-containing components used according to the invention give particularly good results in the case of paper varieties containing groundwood or peroxide-treated groundwood. However, the method according to the invention can also advantageously be used in the case of other types of paper. Thus, for example, the pulp or fiber suspension (in addition to the groundwood) may also contain high purified fiber fractions, as is the case, for example, in so-called newsprint paper. The present invention furthermore gives very good results in the case of so-called "deinked pulp" (DIP stock). This is a paper stock which is produced from wastepaper. There, in particular hydrophobic stickies result from the stickies of magazines and newspaper.
These too can be readily bound in the end product with the stevensite- and/or cerolite-containing components used according to the invention. Further so-called paper stocks in which the stevensite- and/or cerolite-containing components according to the invention are advantageously used may comprise TMP stock (thermomechanical pulp), sulfate pulp, sulfite pulp and mixtures of different pulps. Depending on the paper type and localization of the paper mill, such pulps are mixed in different ratios and adapted to the material requirements of the end product.
The preferred proportion of groundwood in the paper pulp or fiber suspension is, in an advantageous embodiment according to the invention, at least 10% by weight, in particular at least 30% by weight, based in each case on the dry weight of the total pulp or suspension.
The at least one stevensite- and/or cerolite-containing component in the method according to the invention probably acts, without the invention being limited to the correctness of this assumption, by binding the interfering substances or interacting with them and thus counteracting the aggregation and deposition onto the parts of the paper machine, such as, for example, the rolls.
The concentration of the interfering substances during papermaking is typically determined in the white water by the three customary methods of cation demand (cationic charge demand), turbidity measurement and chemical oxygen demand. In the case of the cation demand, it is assumed that the interfering substances are all negatively charged and the white water is filtered in short-chain cationic polyelectrolytes. The consumption is converted into the so-called cation demand. In the case of the turbidity measurement, it is assumed that the interfering substances are partly present in colloidal form and their concentration can be determined via the extinction caused by the turbidity. In the case of the chemical oxygen demand the existing proportion of organic compounds is tested via an oxidizing agent. Although these methods are very widely used in the paper world, more recent investigations have shown that they average over the total ingredients in the white water and only partly detect particularly critical interfering substances. This is evident, for example, from the fact that the so-called tree resin colloids, which are partly composed of hydrophobic compounds, may carry only low surface charges and hence contribute little to the cation demand. On the other hand, lignins have a high cation demand; if they are present in the white water, they interfere only very little in the papermaking.
More recent investigations furthermore show that there is not always a correlation between the turbidity measurement and the concentration of colloidal interfering substances. On the basis of this more recent experience with the customary methods for determining interfering substances, stevensite- and/or cerolite-containing components according to the invention were also characterized in their action by more recent methods. One such method is, for example, a gas chromatographic analysis of the white water by the method of F. Orsa and B. Holmbom, "A
Convenient Method for the Determination of Wood Extractives in Papermaking Process Waters and Effluents", Journal of Pulp and Paper Science, vol. 20 no. 12 December 1994, page J361. In the production of a groundwood-containing paper the individual tree resin components are determined in their concentration by a gas chromatographic method. This is a complete, quantitative analysis, whereas the standard method of determination such as turbidity, cation demand and chemical oxygen demand, is actually to be rated at best as being only semiquantitative. Furthermore, it was shown by L. Vahasalo et al. (loc. cit., cf.
"Flowcytometrische Analyse des Siebwassers [Flow-cytometric analysis of white water]", further below) that the so-called flow cytometry is very successful for determining the number of colloidal interfering substances in paper white waters. This new method was therefore also used in the present invention for demonstrating the effect of the stevensite- and/or cerolite-containing components according to the invention for reducing interfering substance.
The addition of the at least one stevensite- and/or cerolite-containing component used according to the invention to the pulp or fiber suspension can be effected at any desired point in the papermaking which is suitable for the person skilled in the art.
In particular, the addition directly in the pulper is also advisable because there is the possibility there of a long contact time with the paper stock, and it is probable that there will be a high degree of binding of interfering substances.
Further addition points lie in the entire so-called high-consistency stock range. Addition for the "dissolved air-flotation" for water purification is also conceivable. In many cases, an existing addition point for additives, for example in the form of a metering apparatus or metering pump, will also be present in the apparatuses used in each case for papermaking and can be used for the addition of stevensite- and/or cerolite-containing component(s) used according to the invention. The stevensite- and/or cerolite-containing components may be used both in powder form and in the form of a suspension or slurry.
The suspension or slurry will in many cases permit better meterability and is more easily automatatable in industrial, continuous processes.
It has furthermore been found that the action of the stevensite-and/or cerolite-containing components used according to the invention is particularly positive when a certain particle size is maintained. Thus, according to a particularly preferred embodiment of the invention, the particle size of the stevensite- and/or cerolite-containing components is chosen so that the wet sieve residue at 45 pm is less than 2% by weight, preferably less than 1% by weight, in particular less than 0.5%
by weight. The determination of the wet sieve residue is explained in more detail before the examples. The preferred particle size can also be determined by the light scattering method (Malvern). In a particularly preferred embodiment according to the invention, the median particle size (D50) (based on the sample volume) is from 0.5 to 10 m, in particular from 2 to 8 pm, particularly preferably from 3 to 6}un.
In the present invention, it was surprisingly also found that the use of the stevensite- and/or cerolite-containing components used according to the invention leads to particularly good binding of interfering substances if the use of talc is omitted in the method. Use of cationic polymers, such as, for example, poly(dadmac) or polyacrylamide according to the prior art, can also be reduced or even completely omitted with the aid of the stevensite- and/or cerolite-containing components used according to the invention.
The amounts of the stevensite- and/or cerolite-containing components used in the method according to the invention can be determined by the person skilled in the art on the basis of routine empirical experiments. In most cases, it will be advantageous to use amounts from 0.5 to 12 kg/t of paper pulp or fiber suspension, preferably from 1 to 8 kg/t, in particular from 1.5 to 7 kg/t, based in each case on the anhydrous pulp/suspension (dry weight).
Surprisingly, it was also found in the present invention that the method according to the invention permitted not only very good binding of anionic fractions of interfering substances such as fatty acids, but also outstanding control of hydrophobic fractions of interfering substances, such as sterols, steroyl esters and triglycerides. The results obtained thereby surprisingly surpass those which were obtained with conventional bentonites and those of talc.
A further aspect of the present invention relates to the use of at least one stevensite- and/or cerolite-containing component as described herein for binding interfering substances in papermaking. As mentioned above, the at least one stevensite-and/or cerolite-containing component is preferably used in a paper pulp or fiber suspension which contains groundwood fractions. However, all paper varieties or pulps are included in the use according to the invention. The paper types mentioned further above, such as paper varieties containing groundwood or peroxide-bleached groundwood, those which also contain highly purified fiber fractions (in addition to the groundwood), as is the case, for example, with so-called newsprint paper, so-called "deinked pulp" (DIP stock), TMP stock (thermomechanical pulp), sulfate pulp, sulfite pulp and mixtures of different pulps are particularly preferred.
Method section: Unless stated otherwise, the analytical methods stated below are used:
1. Determination of the cation exchange capacity (CEC analysis) and of the cation fractions Principle: The clay (the stevensite- and/or cerolite-containing component) is treated with a large excess of aqueous NH4-Cl solution and washed out, and the amount of NH9+ remaining on the clay is determined according to Kjeldahl.
Me+(clay)-+ NHy+ NH4+(clay)-+Me+
(Me+ = H+, K+, Na+, 1/2 Ca2+, 1/2 Mg2+.... ) Apparatuses: sieve, 63 pm; conical flask with ground glass joint, 300 ml; analytical balance; membrane suction filter, 400 ml; cellulose nitrate filter, 0.15 }un (from Sartorius);
drying oven; reflux condenser; hot plate; distillation unit, VAPODEST-5 (from Gerhardt, no. 6550); graduated flask, 250 ml;
flame AAS; chemicals: 2N NH4C1 solution, Nessler's reagent (from Merck, art. no. 9028); boric acid solution, 2% strength; sodium hydroxide solution, 32% strength; 0.1N hydrochloric acid; NaCl solution, 0.1% strength; KC1 solution, 0.1% strength.
Procedure: 5 g of clay are sieved through a 63 um sieve and dried at 110 C. Thereafter, exactly 2 g are weighed into the conical flask with a ground glass joint on the analytical balance by differential weighing, and 100 ml of 2N NH9C1 solution are added. The suspension is boiled under reflux for one hour. In the case of clays having a high CaCo3 content, ammonia may be evolved. In these cases, NH4C1 solution must be added until the odor of ammonia is no longer perceptible. An additional check can be carried out with a moist indicator paper. After a standing time of about 16 h NH4+-clay is filtered off over a membrane suction filter and washed with demineralized water (about 800 ml) until it is substantially free of ions. The testing of the wash water for freedom from ions is carried out for NH4+ ions with a Nessler's reagent which is sensitive to them. The washing number can vary from 30 minutes to 3 days, depending on the type of clay. The washed-out NH4+-clay is removed from the filter, dried at 110 C for 2 h, milled, sieved (63 pm sieve) and dried again at 110 C for 2 h. Thereafter, the NH4+ content of the clay is determined according to Kjeldahl.
Calculation of the CEC: The CEC of the clay is the NH4+ content of the NH4+-clay, determined by means of Kjeldahl (for CEC of some clay minerals, cf. appendix). The data are given in meq/100 g of clay.
Example: Nitrogen content = 0.93%;
Molecular weight: N = 14.0067 g/mol 0.93 x 1000 CEC = = 66.4 meq/100 g 14.0067 CEC = 66.4 meq/100 g of NH4+-clay Exchanged cations and proportions thereof:
The cations liberated by the exchange are present in the wash water (filtrate). The proportion and the type of monovalent cations ("exchangeable cations") were determined spectroscopically in the filtrate according to DIN 38406, part 22. For example, for the AAS determination, the wash water (filtrate) is concentrated, transferred to a 250 ml graduated flask and made up to the mark with demineralized water. Suitable measurement conditions for FAAS are shown in the following tables.
Element Calcium Potassium Lithium Magnesium Sodium Wavelength 285.2 422.7 766.5 670.8 589.0 (nm) (202.6) Gap width 0.2 0.5 0.5 0.5 0.2 (nm) :
Integration time (sec):
Flame gasses: N20/C2H2 air/C2H2 air/CzH2 N20/C2H2 air/C2H2 Background no no no yes no compensation:
Measuring conc. conc. conc. conc. conc.
method:
Ionization 0.1 % KCI 0.1% NaCl 0.1% NaCl 0.1% KCI 0.1% KCI
buffer:
Burner position Calibration standard 1-5 mg/1 1-5 mg/i 2-10 mg/1 0.5-3 mg/1 1-5 mg/l (5-40 mg/1) Element Aluminum Iron Wavelength 309.3 248.3 (nm) :
Gap width 0.5 0.2 (nm):
Integration time (sec): 3 3 Flame gasses: N20/C2H2 air/C2H2 Background compensation: yes no Measuring method: conc. conc.
Ionization buffer: 0.1 % KC1 -Burner position - -Calibration standard 10-50 mg/1 1-5 mg/1 (mg/1):
Calculation of the cations:
Me value (mg/1) x 100 x dilution Me = = meq/100 g 4 x weight taken (in g) x molar mass (g/mol) Molar mass (g/mol): Ca = 20.040; K = 39.096; Li = 6.94;
Mg = 12.156; Na = 22.990; Al = 8.994; Fe = 18.616 In the case of so-called overactivated clays (stevensite- and/or cerolite-containing components), i.e. those which were activated with an amount of, for example, sodium carbonate which is greater than the stoichiometric amount, the sum of the amounts of monovalent cations determined may be greater than the CEC
determined as stated above. In such cases, the total content of monovalent cations (Li, K, Na) is regarded as 100% of the CEC.
2. Determination of the BET surface area:
The determination was effected according to DIN 66131 (multi-point determination).
According to the invention, the position of the diffraction peak at the lattice spacing of about 10 A therefore changes in a characteristic manner in the stevensite used in the mycotoxin adsorbent or in the stevensite-containing component at different humidities or on treatment with ethylene glycol according to fig. 2 of the literature reference Brindley et al. (loc. cit.). In this way, the stevensite used therefore also differs, for example, from pure cerolite.
The expression "stevensite" is intended here also to include stevensite-containing components for the sake of simplicity.
The term "stevensite-containing component" is intended to express the fact that, according to the invention, components which also contain further constituents in addition to stevensite can also be used according to the invention. For example, many commercially available stevensite products contain not only stevensite but also different amounts of accompanying minerals. Moreover, mixtures of stevensite with other constituents, such as, for example, other mineral constituents, in particular phyllosilicates, are also conceivable.
In an embodiment according to the invention, at least one stevensite- and/or cerolite-containing component which consists substantially or completely of stevensite or of at least one stevensite-containing component is used.
In a further aspect according to the invention, the component used contains cerolite or a cerolite phase.
What is to be understood by cerolite is familiar to a person skilled in the art and need not be explained in more detail here. For example, reference may also be made here to Brindley et al. (loc. cit.). The determination of cerolite can be carried out as described there. The chemical analysis of cerolite gives a composition close to R3Si4O10(OH)2=nH2O, where R is mainly Mg and n is from about 0.8 to 1.2. What is characteristic is the diffraction peak at lattice spacing (basal spacing) 10 A, the position of which shows no expansion at different humidities and no thermal contraction up to 500 C. Here, express reference is made to the powder X-ray diffraction patterns for cerolite and the related parts of the text, which are given by G.B. Brindley et al. (loc.
cit.) in fig. 2 Brindley et al. (loc. cit.) in fig. 2. In a possible embodiment according to the invention, the stevensite or the at least one stevensite-containing component is partly or completely replaced by cerolite or at least one cerolite-containing component in the composition according to the invention.
The expression "cerolite" is intended here also to include cerolite-containing components for the sake of simplicity.
The term "cerolite-containing component" is intended to express the fact that, according to the invention, it is also possible to use components which also contain further constituents in addition to cerolite. For example, many commercially available cerolite products contain not only cerolite but also different amounts of accompanying minerals.
Moreover, mixtures of cerolite with other constituents, such as, for example, other mineral constituents, in particular phyllosilicates, are also conceivable.
In an embodiment according to the invention, at least one stevensite- and/or cerolite-containing component which substantially or completely consists of cerolite or of at least one cerolite-containing component is used.
In a further aspect according to the invention, the component used contains both stevensite or a stevensite phase and cerolite or a cerolite phase. It was found that such stevensite- and cerolite-containing components have particularly good properties with regard to binding interfering substances.
According to a preferred embodiment, the stevensite- and/or cerolite-containing component used contains at least 10% by weight, preferably at least 50% by weight, in particular at least 75% by weight, particularly preferably at least 90% by weight, especially preferably at least 95% by weight, of stevensite and/or cerolite. Thus, it was surprisingly found that particularly good binding of interfering substances results if stevensite and/or cerolite represents the main phase mineralogically in the components used according to the invention.
Within the scope of the present invention, it was furthermore found that in particular those stevensite- and/or cerolite-containing components which have a magnesium oxide content of at least 15% by weight, in particular at least 17% by weight, more preferably at least 20% by weight, are suitable.
Corresponding materials are commercially available.
Furthermore, it is preferable if the magnesium oxide content of the stevensite- and/or cerolite-containing components used, in particular of the stevensite or of the stevensite-containing component, is not more than 40% by weight, in particular not more than 35% by weight, in many cases more preferably not more than 32% by weight.
The content of magnesium oxide is also determinative for the exact formation of the layer structure of the material. It is assumed, without limiting the invention to the correctness of this assumption, to the layer structure of the material used according to the invention, in particular of the stevensite, provides a particularly advantageous porosimetry and particularly efficient surfaces for the adsorption of a multiplicity of different interfering substances.
In an embodiment according to the invention, in particular in the case of components having a high proportion of stevensite, the BET surface area (measured according to DIN 66131, cf. method section) is preferably at least 60 m2/g, in particular at least 80 m2/g, especially at least 100 m2/g. These high BET surface areas evidently provide even more efficient adsorption for some interfering substances.
It was furthermore found that in particular those components which have a cation exchange capacity (CEC) of less than 40 meq/100 g, in particular less than 35 meq/100 g, , CA 02620089 2008-02-22 particularly preferably less than 30 meq/100 g, give particularly good results. The CEC can be determined as stated in the method section below.
According to a further preferred embodiment, the stevensite-and/or cerolite-containing components used are those whose CEC is at least 2 meq/100 g, preferably at least 5 meq/100 g, in particular at least 10 meq/100 g, more preferably at least 15 meq/100 g.
"cation exchange capacity" (CEC) is understood as meaning the sum of all exchangeable cations, stated in meq/100 g and determined according to the CEC analysis method, as explained below before the example section (determination of the cation exchange capacity). The cation exchange capacity thus comprises, for example, the sum of all exchangeable divalent and monovalent cations, such as calcium, magnesium, sodium, lithium and potassium ions. For the determination of the cation exchange capacity, the stevensite- and/or cerolite-containing component is treated with an ammonium chloride solution. Owing to the high affinity of the ammonium ions for the stevensite- and/or cerolite-containing component, virtually all exchangeable cations are exchanged by ammonium ions. After separating off and washing, the nitrogen content of the stevensite- and/or cerolite-containing components is determined and the content of ammonium ions is calculated therefrom.
As stated above, the stevensite- and/or cerolite-containing components used according to the invention surprisingly have a substantially better action in the control of interfering substances than the conventionally used products, such as, for example, talc.
Compared with other agents, such as, for example, conventional bentonites, there is a further advantage in that stevensite-and/or cerolite-containing components can as a rule be processed to give (aqueous) slurries or suspensions having a much higher solids content without the processing and metering being adversely affected by an excessively high viscosity of the slurry or suspension. Thus, in many paper mills in practice, the raw materials, including the agents or components used for binding interfering substances, are metered in in liquid form.
The higher the solids content of the slurry or suspension to be metered the smaller is the amount to be metered or to be prepared and to be transported.
In the present invention, it was also surprisingly found that the action of the stevensite- and/or cerolite-containing components with regard to binding interfering substances can be even further increased if they are activated. Particularly in the case of stevensite-containing components, the activation was found to have a good effect. According to the invention, activation is understood here as meaning an at least partial exchange of the intermediate layer cations, in particular of the divalent or polyvalent intermediate layer cations of stevensite in the stevensite-containing component, for monovalent cations.
The exchanged monovalent cations may be in particular H+ or one or more alkali metal cations. Preferred forms of the activation are activations using acid or alkali. A preferred, nonlimiting example of an alkali activation is the activation with sodium carbonate. For this purpose, for example, the pit-moist clay, which usually has water contents of from 25 to 40% by weight of moisture, is mixed with up to 5% by weight, in particular up to 4% by weight, of sodium carbonate, potassium carbonate or other salts of alkali metal ions, such as, for example, phosphates or citrates, based on anhydrous clay, and, if appropriate, also extruded. Drying and milling are then effected.
Acid activation of the stevensite-containing component can generally be carried out by a treatment with one or more acids.
For this purpose, the component is brought into contact with at least one inorganic and/or organic acid. In principle, any method for the acid activation of clays which is known to the person skilled in the art can be used. In one possible embodiment according to the invention, it is not necessary to wash out the excess acid and the salts forming during the activation. Rather, after addition of the acid, as is usual in the acid activation, no wash step is carried out but the treated component is dried and, if appropriate, milled to the desired particle size.
The acid activation can be effected, for example, with acids in solid form or with an acid solution. Thus, in one embodiment, the activation of the component is carried out in the aqueous phase. For this purpose, the acid in the form of an aqueous solution is brought into contact with the stevensite-containing component. For example it is possible here to adopt a procedure in which the stevensite-containing component, which is preferably provided in the form of a powder, is first suspended in water. The acid, for example in concentrated form, is then added. The stevensite-containing component can, however, also be suspended directly in an aqueous solution of the acid, or the aqueous solution of the acid can be added to the stevensite-containing component. According to an advantageous embodiment, the aqueous acid solution can, for example, be sprayed onto a preferably crushed or pulverulent stevensite-containing component, the amount of water preferably being chosen to be as low as possible. For example, a concentrated acid or acid solution is used here. When spraying on small amounts of acid, often only a superficial activation takes place, also referred to as "surface modification". The amount of acid can preferably be chosen to be from 1 to 10% by weight, particularly preferably from 2 to 6% by weight, of a strong acid, in particular of a mineral acid, such as sulfuric acid, based on the anhydrous stevensite-containing component (absolutely dry). If required, excess water can be evaporated off and the activated stevensite-containing component can, if appropriate, be milled to the desired fineness. As already mentioned above, in an embodiment of the method according to the invention, no wash step is required. After addition of the aqueous solution of the acid, drying is only effected, if required, until the desired moisture content is reached. In general, the water content of the activated stevensite-containing component obtained is adjusted to a proportion of less than 20% by weight, preferably less than 10% by weight.
For the activation described above with an aqueous solution of an acid or of a concentrated acid, the acid can be arbitrarily chosen. It is possible to use both mineral acids and organic acids or mixtures of the above acids. It is possible to use customary mineral acids, such as hydrochloric acid, phosphoric acid or sulfuric acid, sulfuric acid being preferred. It is possible to use concentrated or dilute acids or acid solutions.
Organic acids used may be, for example, citric acid or oxalic acid.
In a particularly preferred embodiment according to the invention, the stevensite- and/or cerolite-containing component has, based on the CEC, a proportion of at least 50%, in particular at least 80%, of monovalent cations, such as H+, Na+, K+ and/or Li+. This proportion can be reached or increased, for example, by activation of the component with an acid or an alkali metal salt (e.g. sodium carbonate). At least 90%, in particular about 100%, of monovalent cations, based on the CEC
of the stevensite- and/or cerolite-containing component, are particularly preferred.
The method according to the invention for the use of the stevensite- and/or cerolite-containing components described herein can be used generally in all processes for paper or cardboard production. Accordingly, the expressions paper pulp and fiber suspension are intended generally to include all compositions or streams which contain interfering substances and are used in the production of paper, cardboard, other fibrous materials or the like. Otherwise, the expressions "(paper) pulp"
and "fiber suspension" are familiar to a person skilled in the art and need not be explained in more detail here.
In a preferred embodiment according to the invention, the pulp or the fiber suspension is a suspension containing (fine) groundwood. Groundwood is in general finely digested (finely ground wood, generally without further chemical or thermal treatment). The groundwood suspension is either used directly after comminution or subjected to a peroxide bleach, so-called peroxide-bleached groundwood then forming. It has surprisingly been found that the stevensite- and/or cerolite-containing components used according to the invention give particularly good results in the case of paper varieties containing groundwood or peroxide-treated groundwood. However, the method according to the invention can also advantageously be used in the case of other types of paper. Thus, for example, the pulp or fiber suspension (in addition to the groundwood) may also contain high purified fiber fractions, as is the case, for example, in so-called newsprint paper. The present invention furthermore gives very good results in the case of so-called "deinked pulp" (DIP stock). This is a paper stock which is produced from wastepaper. There, in particular hydrophobic stickies result from the stickies of magazines and newspaper.
These too can be readily bound in the end product with the stevensite- and/or cerolite-containing components used according to the invention. Further so-called paper stocks in which the stevensite- and/or cerolite-containing components according to the invention are advantageously used may comprise TMP stock (thermomechanical pulp), sulfate pulp, sulfite pulp and mixtures of different pulps. Depending on the paper type and localization of the paper mill, such pulps are mixed in different ratios and adapted to the material requirements of the end product.
The preferred proportion of groundwood in the paper pulp or fiber suspension is, in an advantageous embodiment according to the invention, at least 10% by weight, in particular at least 30% by weight, based in each case on the dry weight of the total pulp or suspension.
The at least one stevensite- and/or cerolite-containing component in the method according to the invention probably acts, without the invention being limited to the correctness of this assumption, by binding the interfering substances or interacting with them and thus counteracting the aggregation and deposition onto the parts of the paper machine, such as, for example, the rolls.
The concentration of the interfering substances during papermaking is typically determined in the white water by the three customary methods of cation demand (cationic charge demand), turbidity measurement and chemical oxygen demand. In the case of the cation demand, it is assumed that the interfering substances are all negatively charged and the white water is filtered in short-chain cationic polyelectrolytes. The consumption is converted into the so-called cation demand. In the case of the turbidity measurement, it is assumed that the interfering substances are partly present in colloidal form and their concentration can be determined via the extinction caused by the turbidity. In the case of the chemical oxygen demand the existing proportion of organic compounds is tested via an oxidizing agent. Although these methods are very widely used in the paper world, more recent investigations have shown that they average over the total ingredients in the white water and only partly detect particularly critical interfering substances. This is evident, for example, from the fact that the so-called tree resin colloids, which are partly composed of hydrophobic compounds, may carry only low surface charges and hence contribute little to the cation demand. On the other hand, lignins have a high cation demand; if they are present in the white water, they interfere only very little in the papermaking.
More recent investigations furthermore show that there is not always a correlation between the turbidity measurement and the concentration of colloidal interfering substances. On the basis of this more recent experience with the customary methods for determining interfering substances, stevensite- and/or cerolite-containing components according to the invention were also characterized in their action by more recent methods. One such method is, for example, a gas chromatographic analysis of the white water by the method of F. Orsa and B. Holmbom, "A
Convenient Method for the Determination of Wood Extractives in Papermaking Process Waters and Effluents", Journal of Pulp and Paper Science, vol. 20 no. 12 December 1994, page J361. In the production of a groundwood-containing paper the individual tree resin components are determined in their concentration by a gas chromatographic method. This is a complete, quantitative analysis, whereas the standard method of determination such as turbidity, cation demand and chemical oxygen demand, is actually to be rated at best as being only semiquantitative. Furthermore, it was shown by L. Vahasalo et al. (loc. cit., cf.
"Flowcytometrische Analyse des Siebwassers [Flow-cytometric analysis of white water]", further below) that the so-called flow cytometry is very successful for determining the number of colloidal interfering substances in paper white waters. This new method was therefore also used in the present invention for demonstrating the effect of the stevensite- and/or cerolite-containing components according to the invention for reducing interfering substance.
The addition of the at least one stevensite- and/or cerolite-containing component used according to the invention to the pulp or fiber suspension can be effected at any desired point in the papermaking which is suitable for the person skilled in the art.
In particular, the addition directly in the pulper is also advisable because there is the possibility there of a long contact time with the paper stock, and it is probable that there will be a high degree of binding of interfering substances.
Further addition points lie in the entire so-called high-consistency stock range. Addition for the "dissolved air-flotation" for water purification is also conceivable. In many cases, an existing addition point for additives, for example in the form of a metering apparatus or metering pump, will also be present in the apparatuses used in each case for papermaking and can be used for the addition of stevensite- and/or cerolite-containing component(s) used according to the invention. The stevensite- and/or cerolite-containing components may be used both in powder form and in the form of a suspension or slurry.
The suspension or slurry will in many cases permit better meterability and is more easily automatatable in industrial, continuous processes.
It has furthermore been found that the action of the stevensite-and/or cerolite-containing components used according to the invention is particularly positive when a certain particle size is maintained. Thus, according to a particularly preferred embodiment of the invention, the particle size of the stevensite- and/or cerolite-containing components is chosen so that the wet sieve residue at 45 pm is less than 2% by weight, preferably less than 1% by weight, in particular less than 0.5%
by weight. The determination of the wet sieve residue is explained in more detail before the examples. The preferred particle size can also be determined by the light scattering method (Malvern). In a particularly preferred embodiment according to the invention, the median particle size (D50) (based on the sample volume) is from 0.5 to 10 m, in particular from 2 to 8 pm, particularly preferably from 3 to 6}un.
In the present invention, it was surprisingly also found that the use of the stevensite- and/or cerolite-containing components used according to the invention leads to particularly good binding of interfering substances if the use of talc is omitted in the method. Use of cationic polymers, such as, for example, poly(dadmac) or polyacrylamide according to the prior art, can also be reduced or even completely omitted with the aid of the stevensite- and/or cerolite-containing components used according to the invention.
The amounts of the stevensite- and/or cerolite-containing components used in the method according to the invention can be determined by the person skilled in the art on the basis of routine empirical experiments. In most cases, it will be advantageous to use amounts from 0.5 to 12 kg/t of paper pulp or fiber suspension, preferably from 1 to 8 kg/t, in particular from 1.5 to 7 kg/t, based in each case on the anhydrous pulp/suspension (dry weight).
Surprisingly, it was also found in the present invention that the method according to the invention permitted not only very good binding of anionic fractions of interfering substances such as fatty acids, but also outstanding control of hydrophobic fractions of interfering substances, such as sterols, steroyl esters and triglycerides. The results obtained thereby surprisingly surpass those which were obtained with conventional bentonites and those of talc.
A further aspect of the present invention relates to the use of at least one stevensite- and/or cerolite-containing component as described herein for binding interfering substances in papermaking. As mentioned above, the at least one stevensite-and/or cerolite-containing component is preferably used in a paper pulp or fiber suspension which contains groundwood fractions. However, all paper varieties or pulps are included in the use according to the invention. The paper types mentioned further above, such as paper varieties containing groundwood or peroxide-bleached groundwood, those which also contain highly purified fiber fractions (in addition to the groundwood), as is the case, for example, with so-called newsprint paper, so-called "deinked pulp" (DIP stock), TMP stock (thermomechanical pulp), sulfate pulp, sulfite pulp and mixtures of different pulps are particularly preferred.
Method section: Unless stated otherwise, the analytical methods stated below are used:
1. Determination of the cation exchange capacity (CEC analysis) and of the cation fractions Principle: The clay (the stevensite- and/or cerolite-containing component) is treated with a large excess of aqueous NH4-Cl solution and washed out, and the amount of NH9+ remaining on the clay is determined according to Kjeldahl.
Me+(clay)-+ NHy+ NH4+(clay)-+Me+
(Me+ = H+, K+, Na+, 1/2 Ca2+, 1/2 Mg2+.... ) Apparatuses: sieve, 63 pm; conical flask with ground glass joint, 300 ml; analytical balance; membrane suction filter, 400 ml; cellulose nitrate filter, 0.15 }un (from Sartorius);
drying oven; reflux condenser; hot plate; distillation unit, VAPODEST-5 (from Gerhardt, no. 6550); graduated flask, 250 ml;
flame AAS; chemicals: 2N NH4C1 solution, Nessler's reagent (from Merck, art. no. 9028); boric acid solution, 2% strength; sodium hydroxide solution, 32% strength; 0.1N hydrochloric acid; NaCl solution, 0.1% strength; KC1 solution, 0.1% strength.
Procedure: 5 g of clay are sieved through a 63 um sieve and dried at 110 C. Thereafter, exactly 2 g are weighed into the conical flask with a ground glass joint on the analytical balance by differential weighing, and 100 ml of 2N NH9C1 solution are added. The suspension is boiled under reflux for one hour. In the case of clays having a high CaCo3 content, ammonia may be evolved. In these cases, NH4C1 solution must be added until the odor of ammonia is no longer perceptible. An additional check can be carried out with a moist indicator paper. After a standing time of about 16 h NH4+-clay is filtered off over a membrane suction filter and washed with demineralized water (about 800 ml) until it is substantially free of ions. The testing of the wash water for freedom from ions is carried out for NH4+ ions with a Nessler's reagent which is sensitive to them. The washing number can vary from 30 minutes to 3 days, depending on the type of clay. The washed-out NH4+-clay is removed from the filter, dried at 110 C for 2 h, milled, sieved (63 pm sieve) and dried again at 110 C for 2 h. Thereafter, the NH4+ content of the clay is determined according to Kjeldahl.
Calculation of the CEC: The CEC of the clay is the NH4+ content of the NH4+-clay, determined by means of Kjeldahl (for CEC of some clay minerals, cf. appendix). The data are given in meq/100 g of clay.
Example: Nitrogen content = 0.93%;
Molecular weight: N = 14.0067 g/mol 0.93 x 1000 CEC = = 66.4 meq/100 g 14.0067 CEC = 66.4 meq/100 g of NH4+-clay Exchanged cations and proportions thereof:
The cations liberated by the exchange are present in the wash water (filtrate). The proportion and the type of monovalent cations ("exchangeable cations") were determined spectroscopically in the filtrate according to DIN 38406, part 22. For example, for the AAS determination, the wash water (filtrate) is concentrated, transferred to a 250 ml graduated flask and made up to the mark with demineralized water. Suitable measurement conditions for FAAS are shown in the following tables.
Element Calcium Potassium Lithium Magnesium Sodium Wavelength 285.2 422.7 766.5 670.8 589.0 (nm) (202.6) Gap width 0.2 0.5 0.5 0.5 0.2 (nm) :
Integration time (sec):
Flame gasses: N20/C2H2 air/C2H2 air/CzH2 N20/C2H2 air/C2H2 Background no no no yes no compensation:
Measuring conc. conc. conc. conc. conc.
method:
Ionization 0.1 % KCI 0.1% NaCl 0.1% NaCl 0.1% KCI 0.1% KCI
buffer:
Burner position Calibration standard 1-5 mg/1 1-5 mg/i 2-10 mg/1 0.5-3 mg/1 1-5 mg/l (5-40 mg/1) Element Aluminum Iron Wavelength 309.3 248.3 (nm) :
Gap width 0.5 0.2 (nm):
Integration time (sec): 3 3 Flame gasses: N20/C2H2 air/C2H2 Background compensation: yes no Measuring method: conc. conc.
Ionization buffer: 0.1 % KC1 -Burner position - -Calibration standard 10-50 mg/1 1-5 mg/1 (mg/1):
Calculation of the cations:
Me value (mg/1) x 100 x dilution Me = = meq/100 g 4 x weight taken (in g) x molar mass (g/mol) Molar mass (g/mol): Ca = 20.040; K = 39.096; Li = 6.94;
Mg = 12.156; Na = 22.990; Al = 8.994; Fe = 18.616 In the case of so-called overactivated clays (stevensite- and/or cerolite-containing components), i.e. those which were activated with an amount of, for example, sodium carbonate which is greater than the stoichiometric amount, the sum of the amounts of monovalent cations determined may be greater than the CEC
determined as stated above. In such cases, the total content of monovalent cations (Li, K, Na) is regarded as 100% of the CEC.
2. Determination of the BET surface area:
The determination was effected according to DIN 66131 (multi-point determination).
3. Determination of the wet sieve residue:
With the use of pigments and fillers, it is of interest whether the material to be investigated contains coarse fractions which differ in their particle size from the normal particles and how much of said coarse fractions said material contains. These fractions are determined by sieving an aqueous suspension with water as wash liquid. The wet sieve residue is considered to be the residue determined under specified conditions.
Apparatuses: Analytical balance, plastic beaker, pendraulik LD 50; sieve: 200 mm diameter, mesh size 0.025 (25 pm), 0.045 mm (45 pm), 0.053 mm (53 }zm) or 0.063 mm (63 pm); ultrasonic bath.
First, a 5% strength suspension of the component to be investigated (stevensite- and/or cerolite-containing component) (oven dry, i.e. after drying at 110 C) in 2000 g of water was prepared. For this purpose, the component is stirred in at 930 rpm in about 5 min. After a stirring time of a further 15 min at 1865 rpm, the suspension is poured into the cleaned and dried sieve (mesh size 45 pm) and washed with flowing tap water while tapping until the wash water runs out clear. After the washing of the sieve residue with tap water the sieve is placed for 5 min in an ultrasonic bath in order to sieve off the remaining fine fractions. When using the sieve in the ultrasonic bath, it should be ensured that no air remains between water surface and sieve bottom. After the ultrasonic treatment, rinse again briefly with tap water. Thereafter, the sieve is removed and the water in the ultrasonic bath is replenished. The procedure in the ultrasonic bath is repeated until contamination of the water is no longer detectable. The sieve with the remaining residue is dried to concentrate (oven dry) in a forced-circulation drying oven. After cooling, the residue is transferred by means of a brush into a dish. Evaluation: wet sieve residue (WSR) in (%), based on the amount weighed out.
With the use of pigments and fillers, it is of interest whether the material to be investigated contains coarse fractions which differ in their particle size from the normal particles and how much of said coarse fractions said material contains. These fractions are determined by sieving an aqueous suspension with water as wash liquid. The wet sieve residue is considered to be the residue determined under specified conditions.
Apparatuses: Analytical balance, plastic beaker, pendraulik LD 50; sieve: 200 mm diameter, mesh size 0.025 (25 pm), 0.045 mm (45 pm), 0.053 mm (53 }zm) or 0.063 mm (63 pm); ultrasonic bath.
First, a 5% strength suspension of the component to be investigated (stevensite- and/or cerolite-containing component) (oven dry, i.e. after drying at 110 C) in 2000 g of water was prepared. For this purpose, the component is stirred in at 930 rpm in about 5 min. After a stirring time of a further 15 min at 1865 rpm, the suspension is poured into the cleaned and dried sieve (mesh size 45 pm) and washed with flowing tap water while tapping until the wash water runs out clear. After the washing of the sieve residue with tap water the sieve is placed for 5 min in an ultrasonic bath in order to sieve off the remaining fine fractions. When using the sieve in the ultrasonic bath, it should be ensured that no air remains between water surface and sieve bottom. After the ultrasonic treatment, rinse again briefly with tap water. Thereafter, the sieve is removed and the water in the ultrasonic bath is replenished. The procedure in the ultrasonic bath is repeated until contamination of the water is no longer detectable. The sieve with the remaining residue is dried to concentrate (oven dry) in a forced-circulation drying oven. After cooling, the residue is transferred by means of a brush into a dish. Evaluation: wet sieve residue (WSR) in (%), based on the amount weighed out.
4. Particle size determination according to Malvern:
This is a customary method. A Mastersizer from Malvern Instruments Ltd, UK, was used according to the manufacturer's instructions. The measurements were carried out with a sample chamber provided ("dry powder feeder") in air and the values based on the sample volume were determined.
5. Investigation of the binding of interfering substances:
In the investigation of the binding of interfering substances, the following procedure was adopted:
a) Preparation of paper stock and filtration:
Experiments with peroxide-bleached groundwood The chosen paper stock (peroxide-bleached groundwood) can either be obtained directly from the paper mill or stored in a refrigerator before use. The paper stock was then thoroughly shaken at 10 g absolutely dry and diluted to 1% with warm demineralized water in a 2000 ml beaker. While being stirred at 150 rpm, the paper stock batch warmed up to 40 C with the aid of a hot plate. When the temperature is reached, the amount of adsorbent to be tested is added to the paper stock batch with the aid of a Pasteur pipette. Thereafter, the adsorption time in the stock batch is fixed at 30 min at 40 C and the mixture is stirred for this time at 150 rpm. For the white water preparation, 1000 g of this dilute stock batch (1% by weight solids content) is drained in a drainage and retention apparatus (Mutek DF3 03 from Mutek, Germany) for 420 seconds (170 pm sieve, stirring speed 700 rpm). The white water samples were investigated analytically (cf. examples).
This is a customary method. A Mastersizer from Malvern Instruments Ltd, UK, was used according to the manufacturer's instructions. The measurements were carried out with a sample chamber provided ("dry powder feeder") in air and the values based on the sample volume were determined.
5. Investigation of the binding of interfering substances:
In the investigation of the binding of interfering substances, the following procedure was adopted:
a) Preparation of paper stock and filtration:
Experiments with peroxide-bleached groundwood The chosen paper stock (peroxide-bleached groundwood) can either be obtained directly from the paper mill or stored in a refrigerator before use. The paper stock was then thoroughly shaken at 10 g absolutely dry and diluted to 1% with warm demineralized water in a 2000 ml beaker. While being stirred at 150 rpm, the paper stock batch warmed up to 40 C with the aid of a hot plate. When the temperature is reached, the amount of adsorbent to be tested is added to the paper stock batch with the aid of a Pasteur pipette. Thereafter, the adsorption time in the stock batch is fixed at 30 min at 40 C and the mixture is stirred for this time at 150 rpm. For the white water preparation, 1000 g of this dilute stock batch (1% by weight solids content) is drained in a drainage and retention apparatus (Mutek DF3 03 from Mutek, Germany) for 420 seconds (170 pm sieve, stirring speed 700 rpm). The white water samples were investigated analytically (cf. examples).
Experiments with DIP
The wastepaper stock ("DIP") was diluted to a solids content of 1% with water at 40 C and homogenized with a stirring rod ("ESGE-Zauberstab", ESGE, Switzerland) with the use of a so-called beater disk with 30 s at speed II.
Thereafter, stirring was effected at 150 rpm, the adsorbent (stevensite- or cerolite-containing component) was added and stirring was then effected for a further 30 min using a magnetic stirrer. Finally, drainage was effected as in the case of the groundwood experiments (cf. last section). The white water was investigated by means of flow cytometry.
b) Flowcytometric analysis of the white water:
Here, so-called flow cytometry was used, as described in Vahasalo et al., "Use of Flow Cytometry In Wet End Research", Paper Technology, 44 (1), page 45, February 2003, in "Effects of pH and calcium chloride on pitch in peroxide-bleached mechanical pulp suspensions", 7th European Workshop on Lignocellulosics and Pulp, August 26-29, 2002, Abo, Finland, and in "Flow Cytometry of Bacteria and Wood Resin Particles in Paper Production", Nordic Pulp and Paper Research Journal, vol. 19 no. 4/2004, page 450. In brief, the light scattering method for counting the particles is combined with fluorescence marking.
In order to stain the hydrophobic particles in the white water of the wastepaper stock or the pitch particles in the white water of the groundwood with fluorescence dye for the flow cytometry, the dye Nile Red from Molecular Probes/Invitrogen Detection Technologies (Invitrogen Corporation, 1600 Faraday Avenue, PO Box 6482 Carlsbad, California 92008 USA), as mentioned in the above article, was used.
The wastepaper stock ("DIP") was diluted to a solids content of 1% with water at 40 C and homogenized with a stirring rod ("ESGE-Zauberstab", ESGE, Switzerland) with the use of a so-called beater disk with 30 s at speed II.
Thereafter, stirring was effected at 150 rpm, the adsorbent (stevensite- or cerolite-containing component) was added and stirring was then effected for a further 30 min using a magnetic stirrer. Finally, drainage was effected as in the case of the groundwood experiments (cf. last section). The white water was investigated by means of flow cytometry.
b) Flowcytometric analysis of the white water:
Here, so-called flow cytometry was used, as described in Vahasalo et al., "Use of Flow Cytometry In Wet End Research", Paper Technology, 44 (1), page 45, February 2003, in "Effects of pH and calcium chloride on pitch in peroxide-bleached mechanical pulp suspensions", 7th European Workshop on Lignocellulosics and Pulp, August 26-29, 2002, Abo, Finland, and in "Flow Cytometry of Bacteria and Wood Resin Particles in Paper Production", Nordic Pulp and Paper Research Journal, vol. 19 no. 4/2004, page 450. In brief, the light scattering method for counting the particles is combined with fluorescence marking.
In order to stain the hydrophobic particles in the white water of the wastepaper stock or the pitch particles in the white water of the groundwood with fluorescence dye for the flow cytometry, the dye Nile Red from Molecular Probes/Invitrogen Detection Technologies (Invitrogen Corporation, 1600 Faraday Avenue, PO Box 6482 Carlsbad, California 92008 USA), as mentioned in the above article, was used.
c) Gas chromatographic analysis of the white water:
Here, the method of F. Orsa and B. Holmbom "A Convenient Method for the Determination of Wood Extractives in Papermaking Process Waters and Effluents", Journal of Pulp and Paper Science, vol.
20 no. 12, December 1994, page J361, was used.
The figures show the following:
Fig. 1 shows a graph of the hydrophobic particles in the white water at different doses of the additives Sorb 1 and Sorb 2 according to the invention and cationized talc as a comparative additive.
Fig. 2 shows the graph of the pitch particles in the white water at different doses of the additives Sorb 1 and Sorb 2 according to the invention and cationized talc as comparative additive.
Measurement was effected by means of flow cytometry.
Fig. 3 shows the graph of the concentration of the extractives in the white water at different doses of the additives Sorb 1 and Sorb 2 according to the invention and cationized talc as a comparative additive. The extractives were measured by means of gas chromatography.
The invention is illustrated further with reference to the nonlimiting examples below.
Example 1:
The following materials were investigated for the binding of interfering substances.
The following two stevensite-containing materials, in each case as milled raw clays, were used for the investigations, the two raw clays being milled to a particle size customary for paper applications. For this purpose, a wet sieve residue of < 1% by weight at 45 pm was established by the milling.
The median particle sizes (D50, volume-based) were from 2 to 8 pm. The water content of the samples was 10 4%.
Stevensite as the main phase was confirmed according to Brindley et al. (loc. cit.) and Martin de Vidales et al.
(loc. cit.). In the two materials Sorb 1 and Sorb 2 used, a proportion of cerolite was also detected. As described in the above two literature references, stevensite can be distinguished from cerolite and other smectitic phyllosilicates inter alia on the basis of the powder X-ray diffraction patterns and the shift of the diffraction patterns after treatment with ethylene glycol, after heating or at different humidities. For characterizing the materials according to the invention, it is also possible to use the magnesium oxide content and the CEC.
The analytical data on the materials used according to the invention are summarized in tables 1 to 3 below.
Table 1: Analytical data BET surface area, Cation exchange capacity (CEC), m2/g meq/100 g Sorb 1 125.3 20 Sorb 2 180.1 27 Table 2: Accompanying minerals Accompanying minerals (from X-ray diffractometry) Sorb 1 2-3% of quartz, 2-3% of feldspar, 0.5-1% of calcite Sorb 2 1-2% of quartz, 2% of feldspar, 0.5-1% of calcite Table 3: Silicate analysis Sorb 1 Sorb 2 A1203, % 6.6 7.1 Fe203, % 1.9 2.6 CaO, % 1.1 1.7 MgO, % 26.0 22.3 Na20, % 0.32 0.35 K20, % 1.4 1.3 Ti02, % 0.25 0.24 Si02, % 52.0 52.5 Si02/MgO ratio 2.00 2.35 Loss on ignition, % 9.5 11.2 Example 2 A filtration experiment with a highly loaded wastepaper stock is carried out according to the above description. Before the filtration, the additives according to the invention (stevensite- and/or cerolite-containing components) were added to this paper stock in a dose of 3 kg/t and 6 kg/t, based in each case on the dry weight of the paper stock. In reference filtration experiments, filtration was also effected without addition of additives. Furthermore, cationized talc in a dose of 3 kg/t and 6 kg/t was used as a comparative system.
The white waters were characterized by means of flow cytometry (see above) with regard to the concentration of hydrophobic particles. The results are shown graphically in fig. 1.
Fig. 1 shows that the additives according to the invention substantially reduce the concentration of the hydrophobic particles in the white water, whereas the cationized talc used as a comparison showed no significant effect at the same use concentration.
Example 3 Filtration experiments analogous to example 2 were carried out with a peroxide-bleached groundwood. The additives according to the invention were once again metered in in a concentration of 3 kg/t and 6 kg/t, based on the dry weight of the paper stock.
Sorb 2 in a form activated with alkali was added as an additional additive according to the invention (= Sorb 3). This material was prepared by kneading of the moist materials Sorb 2 with 3% of anhydrous sodium carbonate and subsequent drying and milling (wet sieve residue below 1% by weight, median particle size (D50) from 1 to 6 um).
The white waters are investigated both with the aid of flow cytometry and by the gas chromatographic method according to Orsa and Holmbom (see above).
Fig. 2 shows the results of the flow cytometry. In this paper stock too, the two additives Sorb 1 and Sorb 2 according to the invention led to a substantial reduction in the number of pitch particles in the white water. Once again, the comparative material (cationized talc) showed no significant effect even in a dose of 9 kg/t.
Fig. 3 shows the characterization of the white water by means of gas chromatography. The results found here correlate very well with those of flow cytometry.
The data obtained by the two investigation methods furthermore show that alkaline activation of the material Sorb 2 according to the invention leads to a considerable improvement in the binding of interfering substances in the paper pulp or to a further reduction in the interfering substances in the white water (cf. Sorb 3). It is assumed that this effect is caused by an exchange of Ca2+ ions for Na+ ions (100% of the CEC) in the stevensite phase.
Here, the method of F. Orsa and B. Holmbom "A Convenient Method for the Determination of Wood Extractives in Papermaking Process Waters and Effluents", Journal of Pulp and Paper Science, vol.
20 no. 12, December 1994, page J361, was used.
The figures show the following:
Fig. 1 shows a graph of the hydrophobic particles in the white water at different doses of the additives Sorb 1 and Sorb 2 according to the invention and cationized talc as a comparative additive.
Fig. 2 shows the graph of the pitch particles in the white water at different doses of the additives Sorb 1 and Sorb 2 according to the invention and cationized talc as comparative additive.
Measurement was effected by means of flow cytometry.
Fig. 3 shows the graph of the concentration of the extractives in the white water at different doses of the additives Sorb 1 and Sorb 2 according to the invention and cationized talc as a comparative additive. The extractives were measured by means of gas chromatography.
The invention is illustrated further with reference to the nonlimiting examples below.
Example 1:
The following materials were investigated for the binding of interfering substances.
The following two stevensite-containing materials, in each case as milled raw clays, were used for the investigations, the two raw clays being milled to a particle size customary for paper applications. For this purpose, a wet sieve residue of < 1% by weight at 45 pm was established by the milling.
The median particle sizes (D50, volume-based) were from 2 to 8 pm. The water content of the samples was 10 4%.
Stevensite as the main phase was confirmed according to Brindley et al. (loc. cit.) and Martin de Vidales et al.
(loc. cit.). In the two materials Sorb 1 and Sorb 2 used, a proportion of cerolite was also detected. As described in the above two literature references, stevensite can be distinguished from cerolite and other smectitic phyllosilicates inter alia on the basis of the powder X-ray diffraction patterns and the shift of the diffraction patterns after treatment with ethylene glycol, after heating or at different humidities. For characterizing the materials according to the invention, it is also possible to use the magnesium oxide content and the CEC.
The analytical data on the materials used according to the invention are summarized in tables 1 to 3 below.
Table 1: Analytical data BET surface area, Cation exchange capacity (CEC), m2/g meq/100 g Sorb 1 125.3 20 Sorb 2 180.1 27 Table 2: Accompanying minerals Accompanying minerals (from X-ray diffractometry) Sorb 1 2-3% of quartz, 2-3% of feldspar, 0.5-1% of calcite Sorb 2 1-2% of quartz, 2% of feldspar, 0.5-1% of calcite Table 3: Silicate analysis Sorb 1 Sorb 2 A1203, % 6.6 7.1 Fe203, % 1.9 2.6 CaO, % 1.1 1.7 MgO, % 26.0 22.3 Na20, % 0.32 0.35 K20, % 1.4 1.3 Ti02, % 0.25 0.24 Si02, % 52.0 52.5 Si02/MgO ratio 2.00 2.35 Loss on ignition, % 9.5 11.2 Example 2 A filtration experiment with a highly loaded wastepaper stock is carried out according to the above description. Before the filtration, the additives according to the invention (stevensite- and/or cerolite-containing components) were added to this paper stock in a dose of 3 kg/t and 6 kg/t, based in each case on the dry weight of the paper stock. In reference filtration experiments, filtration was also effected without addition of additives. Furthermore, cationized talc in a dose of 3 kg/t and 6 kg/t was used as a comparative system.
The white waters were characterized by means of flow cytometry (see above) with regard to the concentration of hydrophobic particles. The results are shown graphically in fig. 1.
Fig. 1 shows that the additives according to the invention substantially reduce the concentration of the hydrophobic particles in the white water, whereas the cationized talc used as a comparison showed no significant effect at the same use concentration.
Example 3 Filtration experiments analogous to example 2 were carried out with a peroxide-bleached groundwood. The additives according to the invention were once again metered in in a concentration of 3 kg/t and 6 kg/t, based on the dry weight of the paper stock.
Sorb 2 in a form activated with alkali was added as an additional additive according to the invention (= Sorb 3). This material was prepared by kneading of the moist materials Sorb 2 with 3% of anhydrous sodium carbonate and subsequent drying and milling (wet sieve residue below 1% by weight, median particle size (D50) from 1 to 6 um).
The white waters are investigated both with the aid of flow cytometry and by the gas chromatographic method according to Orsa and Holmbom (see above).
Fig. 2 shows the results of the flow cytometry. In this paper stock too, the two additives Sorb 1 and Sorb 2 according to the invention led to a substantial reduction in the number of pitch particles in the white water. Once again, the comparative material (cationized talc) showed no significant effect even in a dose of 9 kg/t.
Fig. 3 shows the characterization of the white water by means of gas chromatography. The results found here correlate very well with those of flow cytometry.
The data obtained by the two investigation methods furthermore show that alkaline activation of the material Sorb 2 according to the invention leads to a considerable improvement in the binding of interfering substances in the paper pulp or to a further reduction in the interfering substances in the white water (cf. Sorb 3). It is assumed that this effect is caused by an exchange of Ca2+ ions for Na+ ions (100% of the CEC) in the stevensite phase.
Claims (14)
1. A method for binding interfering substances in papermaking, comprising the following steps:
a) Provision of at least one stevensite- and/or cerolite-containing component;
b) Provision of a paper pulp or fiber material;
c) Addition of the at least one stevensite- and/or cerolite-containing component to the paper pulp or fiber material;
d) Enabling of the binding of interfering substances to the at least one stevensite- and/or cerolite-containing component in the paper pulp or fiber suspension.
a) Provision of at least one stevensite- and/or cerolite-containing component;
b) Provision of a paper pulp or fiber material;
c) Addition of the at least one stevensite- and/or cerolite-containing component to the paper pulp or fiber material;
d) Enabling of the binding of interfering substances to the at least one stevensite- and/or cerolite-containing component in the paper pulp or fiber suspension.
2. The method as claimed in claim 1, characterized in that the stevensite- and/or cerolite-containing component contains both stevensite and cerolite.
3. The method as claimed in either of the above claims, characterized in that the stevensite- and/or cerolite-containing component is a component activated with acid or alkali.
4. The method as claimed in any of the above claims, characterized in that the stevensite- and/or cerolite-containing component is used in particle form having a median particle size (D50, volume-based) from 0.5 to 10 µm, in particular from 2 to 8 µm, particularly preferably from 3 to 6 µm.
5. The method as claimed in any of the above claims, characterized in that the stevensite- and/or cerolite-containing component has a proportion of at least 50%, in particular at least 80%, preferably at least about 90%, of monovalent cations, such as, for example, H+, Na+, K+ and/or Li+, based on the CEC.
6. The method as claimed in any of the above claims, characterized in that the stevensite- and/or cerolite-containing component is used in particle form with a wet sieve residue of less than 1% by weight at 45 µm.
7. The method as claimed in any of the above claims, characterized in that the addition of the stevensite- and/or cerolite-containing component is effected in the absence of talc.
8. The method as claimed in any of the above claims, characterized in that from about 0.5 to 10 kg/t of paper pulp or fiber suspension (dry weight), in particular from 1 to 7 kg/t of pulp or fiber suspension, are used.
9. The method as claimed in any of the above claims, characterized in that the paper pulp or fiber suspension contains groundwood fractions.
10.The method as claimed in any of the above claims, characterized in that the groundwood fraction in the paper pulp or fiber suspension is at least 10% by weight, in particular at least 30% by weight, based on the total pulp or fiber suspension (dry weight).
11.The use of a stevensite- and/or cerolite-containing component for binding or eliminating interfering substances in papermaking.
12.The use as claimed in the above claim, characterized in that the use is effected in a paper pulp or fiber suspension having groundwood fractions.
13.The use as claimed in any of the above claims, characterized in that the paper pulp or fiber suspension contains hydrophobic fractions of interfering substances.
14.The use as claimed in any of the above claims, characterized in that, in addition to the at least one stevensite- and/or cerolite-containing component, further components, such as retention aids, other agents for eliminating interfering substances, such as talc or bentonites, are added to the paper pulp or fiber suspension.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE102005039850.2 | 2005-08-23 | ||
| DE200510039850 DE102005039850A1 (en) | 2005-08-23 | 2005-08-23 | Stevensite- and / or Kerolith-containing adsorbents for impurity binding in papermaking |
| PCT/EP2006/008214 WO2007022942A1 (en) | 2005-08-23 | 2006-08-21 | Stevensite- and/or cerolite-containing adsorbents for binding interfering substances during the manufacturing of paper |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2620089A1 true CA2620089A1 (en) | 2007-03-01 |
Family
ID=37076236
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002620089A Abandoned CA2620089A1 (en) | 2005-08-23 | 2006-08-21 | Stevensite- and/or cerolite-containing adsorbents for binding interfering substances during the manufacturing of paper |
Country Status (8)
| Country | Link |
|---|---|
| EP (1) | EP1920111A1 (en) |
| JP (1) | JP2009506224A (en) |
| BR (1) | BRPI0614883A2 (en) |
| CA (1) | CA2620089A1 (en) |
| DE (1) | DE102005039850A1 (en) |
| MX (1) | MX2008002390A (en) |
| WO (1) | WO2007022942A1 (en) |
| ZA (1) | ZA200802224B (en) |
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| PL3260597T3 (en) | 2016-06-22 | 2019-11-29 | Buchmann Ges Mit Beschraenkter Haftung | Multi-layer fibre product with an inhibited migration rate of aromatic or saturated hydrocarbons and method for producing the same |
| JP6867207B2 (en) * | 2017-03-28 | 2021-04-28 | 特種東海製紙株式会社 | Inspection method of wood pulp for glass plate interleaving paper and its use, interleaving paper for glass plate, and wood pulp for glass plate interleaving paper or interleaving paper for glass plate |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0639323B2 (en) * | 1987-02-02 | 1994-05-25 | 水澤化学工業株式会社 | Synthetic stevensite and its manufacturing method |
| NZ227526A (en) * | 1988-01-07 | 1990-04-26 | Cyprus Ind Minerals Co | Reduction of pitch in papermaking furnish by addition of particle composites comprising soluble cationic polymer adsorbed on insoluble particles |
| JPH0247394A (en) * | 1988-08-05 | 1990-02-16 | Mizusawa Ind Chem Ltd | Additive for paper making |
| GB9127173D0 (en) * | 1991-12-21 | 1992-02-19 | Vinings Ind Inc | Method for controlling pitch |
| US5368692A (en) * | 1992-01-22 | 1994-11-29 | Vinings Industries Inc. | Method for controlling pitch |
| ES2101035T3 (en) * | 1992-07-02 | 1997-07-01 | Ecc Int Ltd | PROCEDURE FOR THE CONTROL OF RESIN DEPOSITS IN PAPER MANUFACTURE. |
| JPH0665892A (en) * | 1992-08-19 | 1994-03-08 | Mizusawa Ind Chem Ltd | Pitch adsorbent |
| US5407480A (en) * | 1993-09-30 | 1995-04-18 | Vinings Industries, Inc. | Stabilized, high solids, low viscosity smectite slurries, and method of preparation |
| FR2802913B1 (en) * | 1999-12-23 | 2002-02-08 | Inst Francais Du Petrole | PHYLLOSILICATES 2: 1 TRIOCTAEDRICS OF STEVENSITE OR KEROLITE TYPE, PROCESS FOR PREPARATION AND USE IN CATALYSIS |
-
2005
- 2005-08-23 DE DE200510039850 patent/DE102005039850A1/en not_active Withdrawn
-
2006
- 2006-08-21 ZA ZA200802224A patent/ZA200802224B/en unknown
- 2006-08-21 JP JP2008527376A patent/JP2009506224A/en active Pending
- 2006-08-21 CA CA002620089A patent/CA2620089A1/en not_active Abandoned
- 2006-08-21 WO PCT/EP2006/008214 patent/WO2007022942A1/en active Application Filing
- 2006-08-21 EP EP06776998A patent/EP1920111A1/en not_active Withdrawn
- 2006-08-21 MX MX2008002390A patent/MX2008002390A/en active IP Right Grant
- 2006-08-21 BR BRPI0614883-2A patent/BRPI0614883A2/en not_active Application Discontinuation
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| Publication number | Publication date |
|---|---|
| ZA200802224B (en) | 2009-11-25 |
| BRPI0614883A2 (en) | 2011-04-19 |
| EP1920111A1 (en) | 2008-05-14 |
| WO2007022942A1 (en) | 2007-03-01 |
| DE102005039850A1 (en) | 2007-03-08 |
| MX2008002390A (en) | 2008-03-18 |
| JP2009506224A (en) | 2009-02-12 |
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