DE10326738A1 - Process to strengthen paper, paperboard or cardboard by sprayed application of starch particles. - Google Patents

Abstract

In a process to strengthen paper, paperboard or carton during manufacture, discrete starch particles are applied to the material by spray application. The particulate starch is bound in non-woven fibre fleece and is modified by grinding. During the fabrication of multi-layered paper or carton products the starch is applied by spraying between layers. The particulate starch is ground in aqueous suspension or in a non aqueous medium. In a further embodiment particulate starch is formed by precipitation of starch paste in a concentrated saline solution or solvent.

Description

The Invention relates to a method for introducing starch as Mass additive and when spraying in the production of paper, cardboard and cardboard.

Strength and their derivatives are the third most important raw material in production of paper, cardboard and cardboard. In addition to the addition to the pulp suspension become starch products At the moment in the production of paper mainly as a paste solution Glue or film press or by spraying a starch suspension applied to the initially moist paper web.

in the In the context of the present invention, starch also becomes starchy Product, like flour, understood.

by virtue of the multitude of today in the pulp suspension in papermaking The chemical additives that are introduced lead to competition reactions, in particular here of additives among themselves. The preferably used cationically modified starch derivatives don't just compete with the tools needed to generate specific quality parameters of paper and cardboard such as B. hydro phobicity, wet strength or barrier property added but also with those also used in modern paper production absolutely necessary production aids that are only safe Enable production such as B. retention and drainage accelerators, Biocides, fabric deaerators or Störstoffbinder.

main raw materials for the Manufacture of starches and starch products in Germany and in the EC area are, for example, corn, potatoes and wheat.

At the Addition of gelatinized, dissolved Strength for fiber suspension, briefly referred to as "mass use" currently almost exclusively cationic Derivatives used not only because of their charge properties good on the surface of fiber and fillers are adsorbed, but also an optimal flocculation of the suspension ingredients enable. In addition to increasing the strength of the paper, there is also retention the fiber fine and fillers supported in the nonwoven. The receptivity the pulp for colloidal dissolved starch products However, is based on about 1.5 percent by weight of the fiber limited. Therefor there are different causes. So starch and cellulose have a similar one chemical structure. Both are highly hydrophilic substances weakly anionic charge, which has a pronounced tendency to form Hydrogen bonds to have. In watery solution however, these interactions are too weak and are superimposed through the repulsive personnel due to the slightly anionic presence of both substances Surface charge, which, together with the highs that occur during the preparation of the stock mechanical gravity counteract a retention of strength.

Farther leads the Use of different process chemicals and auxiliaries, that of the pulp suspension during the paper and cardboard manufacturing process are added, to competitive reactions. you disturb the adsorption processes on filling and fibrous materials for the formation of coacervates or precipitations, as a result of which to sensitive malfunctions comes. Finally, the leads Use of chemical additives to reduce drainage performance in the wire section. The result is a loss of production of around 10%. Cause for that are primarily the extremely hydrophilic properties of the polyelectrolytes and here in particular the hydrocolloid starch. Also perform economic and ecological reasons in addition, in the past two decades, the specific water requirement lower in the manufacture of paper and cardboard. Was accompanied this development, however, from a concentration of inorganic and organic substances in the circulating water of paper mills. This contaminated circulating water limit the efficiency of the additives on.

There the use of starch products in the pulp suspension instead of pulp to increase strength of paper and cardboard economically is advantageous, paper manufacturers are on a substitution of Fibers interested.

In recently, Past attempts have been made to use the amount of starch in paper to increase so-called dual systems. With the designation "Dual" it becomes whole generally the successive use of oppositely charged chemical additives for fiber suspension called. While the original Dual systems only retention agent systems for improved flocculation, drainage and retention included, the use of oppositely charged is also today starch products designated with it. Strength dual systems serve to increase this of starch up to 10 percent by weight, based on the fiber content in suspension.

From the EP 1 167 434 A1 a method is known in which a dry mixture of an anionic and a cationic starch is gelatinized together and metered into the stock suspension at one point. This mix of starches with A slightly cationic excess charge can be added to the stock suspension in an increased proportion.

task the invention is a method for introducing starch as Mass additive on the one hand and on the other hand when applying starch in the spraying process to hand, with an increase in the starch content in the paper for improvement strength level at high drainage rates and at the same time Relief of the water cycles is achieved.

The The object is achieved by a Process for introducing starch as a bulk additive in the manufacture of paper, cardboard and cardboard solved by that the strength in the form of discrete particulate Particle is introduced.

The Correspondingly introduced particles are only then gelatinized and dried. The starch introduced into discrete particulate particles becomes when used in the stock suspension by filtration in the nonwoven fabric retained. By the replacement of cationic starches through the particular Strength according to the present Invention as a strengthening additive can increase the amount introduced Strength be significantly enlarged. At the Use of cationic strengths in the stock suspension the amount to be introduced was due to transshipment phenomena limited to a maximum of 2 percent by weight. When using the invention particulate Strengthen is no limit up to an additional amount of approx. 8 percent by weight been found.

Out the subclaims following the main claim preferred embodiments of the invention.

Especially The particulate can be advantageous be bound by filtration in the nonwoven.

The Strength can be mechanically modified, with particular advantage is when the mechanical modification is done by grinding the starch. The starch is activated by the grinding process, see above that versus efficiency native untreated starch as an additive to the fiber suspension is significantly increased.

Advantageous can be the particular Strength applied as spray strength become. Ground starches with a reduced gelatinization point applied as spray strength, allow a more effective gelatinization during the web drying.

at The production of multilayer products can be done by applying of spray strengths between the layers prevented excessive migration into the individual layers become, which enables an improved layer adhesion.

The particulate Strength can advantageously be prepared by grinding starch in aqueous suspension are used, preferably ball mills for the grinding process become.

alternative can be the particular Strength by grinding starch be prepared in an anhydrous medium.

Farther can be the particular Strength by precipitation of gelatinized strength in concentrated saline or a solvent be generated.

Likewise let yourself the particular Strength through particulate Gelatinization of starch in a solvent produce.

• – agglomerationsfrei dispergierte ausreichend kleine Teilchen mit
• – strukturierter Oberfläche,
• – in feinster Verteilung auf den Faser- und Füllstoffen
• – zu retendieren und
• - während der Trocknung zu verkleistern.

The addition of particulate non-gelatinized starch products instead of dissolved, gelatinized mass starches to increase the dry strength of paper and cardboard with simultaneous maximum drainage performance is successful on the basis of the present invention because it succeeds:

• - agglomeration-free dispersed with sufficiently small particles
• - structured surface,
• - in the finest distribution on the fiber and fillers
• - to send and
• - gelatinize during drying.

• 1. 300 g native Kartoffelstärke (Trockengehalt: 87%) werden in 470 ml n-Butanol suspendiert und am Rotationsverdampfer kreisend im Wasserbad bei 80 ° bis 90°C bewegt. In die heiße Suspension wird jeweils in 10 ml Schritten Wasser so zudosiert, dass die Bildung von agglomerierten Stärketeilchen verhindert wird. Die Zugabe erfolgt über einen längeren Zeitraum. Der Verkleisterungsvorgang wird mittels mikroskopischer Kontrolle im polarisierten Licht anhand des Verschwindens der Malteser-Kreuze bewertet. Nach einer Zugabemenge von insgesamt 270 ml wird der Versuch beendet und nach dem Absaugen der Stärke auf dem Büchnertrichter das Produkt auf Filterpapier im Luftstrom (Abzug) getrocknet.
• 2. Native Kartoffelstärke in Wasser gemahlen: Jeweils 30 g native Kartoffelstärke wird zusammen mit 1 kg Keramikkugeln und 270 ml Leitungswasser während 30 min in einer Perlmühle bei 6.600 min^–1 für einen Ansatz unter Kühlung gemahlen. Durch die Mahlung wird die Stärke soweit modifiziert, dass die kristalline Struktur des Stärkekorns destabilisiert wird.
• 3. Kartoffelstärke in Petrolether gemahlen: Handelsübliche native Kartoffelstärke wird bei Normaltemperatur im Vakuum zuerst mehrere Tage über Phosphorpentoxid und anschließend über Calciumhydrid getrocknet. Dieses Material zeigte nach der Trockengehaltsbestimmung bei 130 ° C einen Trockengehalt von 99,9 %. Je 30 g dieser speziell getrockneten Kartoffelstärke werden zusammen mit 1 kg Keramikkugeln (Kugeldurchmesser ca. 2 mm) und 270 ml Petrolether (Kochpunkt. < 40 ° C, vorher ebenfalls mit Calciumhydrid getrocknet) unter Kühlung (< 20 ° C) während 30 min. in einer Perlmühle bei 6.600 min^–1 pro Ansatz gemahlen. Das Mahlgut wird wie folgt gewonnen: Mahlkörper, Mahlgut und Lösungsmittel werden in ein Sieb entleert. Der Teil der gemahlenen Kartoffelstärke, der mit dem abfließenden Lösungsmittel in die Vorlage gelangt, ist nach dem Verdunsten des Petrolethers sofort verwendungsfähig. Nach dem Verdunsten des Lösungsmittels aus der Kugelschüttung auf dem Sieb, wird die an den Kugeln lose haftende gemahlene Kartoffelstärke durch leichtes Schütteln des Siebes abgetrennt. Diese Art der Mahlung führt zu Kornbruchstücken mit scharten Bruchkanten.
• 4. Kartoffelstärke, verkleistert und in Aceton gefällt. Eine 5%-ige Slurry aus nativer Kartoffelstärke wird aufgekocht und 10 min bei weniger als 100°C getempert. Die heiße verkleisterte Stärkelösung wird mittels Ultra-Turrax in einem Überschuss in kaltem Aceton gefällt. Nach dem Absetzen der ausgefällten Kartoffelstärke wird das überstehende Aceton abgegossen. Ca. 2–3 min vor dem Zusatz der Stärkesuspension in die Bütte wird diese Aceton-Stärkesuspension in dünnem Strahl langsam zu etwa dem gleichen Volumen Wasser gegeben. Zur Mischung und Dispergierung wird dabei der Ultra-Turrax bei höchster Drehzahl eingesetzt. Die Mischung wird unverzüglich zur Stoffsuspension gegeben und auf der Papiermaschine verarbeitet.

The production of particulate starches for use in the present invention is exemplified below:

• 1. 300 g of native potato starch (dry matter content: 87%) are suspended in 470 ml of n-butanol and agitated on a rotary evaporator in a water bath at 80 ° to 90 ° C. Water is metered into the hot suspension in 10 ml steps so that the formation of agglomerated starch particles is prevented. The addition takes place over a longer period. The gelatinization process is assessed by means of microscopic control in polarized light based on the disappearance of the Maltese crosses. After a total of 270 ml has been added, the experiment is ended and, after the starch has been sucked off on the Buchner funnel, the product is dried on filter paper in an air stream (hood).
• 2. Native potato starch ground in water: 30 g of native potato starch are added together with 1 kg of ceramic balls and 270 ml of tap water in a pearl mill for 30 minutes 6,600 min ^-1 for a batch with cooling. The starch is modified by grinding to such an extent that the crystalline structure of the starch grain is destabilized.
• 3. Potato starch ground in petroleum ether: Commercially available native potato starch is first dried at phosphorus pentoxide for several days at normal temperature and then over calcium hydride. After the dry content determination at 130 ° C., this material showed a dry content of 99.9%. 30 g each of this specially dried potato starch are mixed with 1 kg ceramic balls (ball diameter approx. 2 mm) and 270 ml petroleum ether (boiling point. <40 ° C, previously also dried with calcium hydride) with cooling (<20 ° C) for 30 min. milled in a pearl mill at 6,600 min ^-1 per batch. The regrind is obtained as follows: The grinding media, regrind and solvent are emptied into a sieve. The part of the ground potato starch that gets into the template with the draining solvent can be used immediately after the petroleum ether has evaporated. After the solvent has evaporated from the ball bed on the sieve, the ground potato starch loosely adhering to the balls is separated by gently shaking the sieve. This type of grinding leads to grain fragments with sharp breaking edges.
• 4. Potato starch, gelatinized and precipitated in acetone. A 5% slurry of native potato starch is boiled and annealed for 10 minutes at less than 100 ° C. The hot gelatinized starch solution is precipitated in excess in cold acetone using Ultra-Turrax. After the precipitated potato starch has settled, the excess acetone is poured off. Approximately 2-3 minutes before the starch suspension is added to the chest, this acetone starch suspension is slowly added in a thin stream to approximately the same volume of water. The Ultra-Turrax is used at high speed for mixing and dispersion. The mixture is immediately added to the stock suspension and processed on the paper machine.

Claims (10)

Process for introducing starch as a bulk additive and for spraying in the manufacture of paper, cardboard and cardboard, characterized in that the starch is introduced in the form of discrete particulate particles. A method according to claim 1, characterized in that the particulate Strength is bound by filtration in the nonwoven fabric. A method according to claim 1 or 2, characterized in that that the Strength is mechanically modified. A method according to claim 3, characterized in that the mechanical modification by grinding the starch. Method according to one of claims 1-4, characterized in that that the particulate Strength applied as spray strength becomes. Method according to one of claims 1-5, characterized in that that at multilayer products spray strength between the layers or is sprayed onto the layers. Method according to one of claims 1-6, characterized in that that the particulate Strength through Starch grinding in watery Suspension is processed. Method according to one of claims 1-6, characterized in that that the particulate Strength through Starch grinding is prepared in an anhydrous medium. Method according to one of claims 1-6, characterized in that that the particulate Strength through precipitation of gelatinized strength in concentrated saline or a solvent is produced. Method according to one of claims 1-6, characterized in that that the particulate Strength through particulate Gelatinization of starch in a solvent is produced.