DE10326738B4 - Method for introducing starch as a bulk additive and for spraying in the production of paper, board and cardboard - Google Patents

Abstract

A method of incorporating starch as a bulk additive and spraying in the manufacture of paper, paperboard and cardboard in which the starch is incorporated in the form of discrete particulate particles. characterized in that the starch is mechanically modified.

Description

The 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 the production of paper, cardboard and cardboard. In addition to the addition to the pulp suspension become starch products at present in the production of paper mainly as gelatinized solution by means of Glue or film press or by spraying a starch suspension applied to the initially damp paper web.

in the Under the present invention is under starch also a starchy Product, like flour, understood.

by virtue of the variety of today in the pulp suspension in papermaking introduced chemical additives, it comes here in particular to competing reactions the additives among each other. The preferably used cationic modified starch derivatives not only compete with the tools that are used to generate more specific quality parameters of paper and cardboard such as B. Hydro phobicity, wet strength or barrier property added but also with those also in modern papermaking absolutely necessary production aids, the first a secure Enable production, such as B. retention and drainage accelerators, Biocides, air vents or Störstoffbinder.

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

At the Addition of gelatinized, dissolved Strength to the pulp suspension, in short referred to as "mass use", become present almost exclusively cationic Used derivatives not only because of their charge characteristics good on the surface of fiber and fillers be adsorbed, but also also an optimal flocculation of the suspension ingredients enable. In addition to the increase in strength of the paper is also the retention fiber fines and fillers supported in the fiber fleece. The receptiveness the pulp for colloidal dissolved starch products However, it is about 1.5 percent by weight based on the pulp limited. Therefor There are different causes. So starch and cellulose have a similar one chemical structure. Both are strongly hydrophilic substances with weak anionic charge, which has a pronounced tendency to form Hydrogen bonds to have. In aqueous solution However, these interactions are too weak and are superimposed through the repulsive ones personnel due to the presence of both substances slightly anionic Surface charge, which together with the high occurring in the stock preparation mechanical gravitational forces counteract a retention of the starch.

Farther leads the Use of different process chemicals and adjuvants that the pulp suspension during be added to the manufacturing process of paper and board, to competitive reactions. you disturb the adsorption processes at filling and fibrous materials for the formation of coacervates or precipitates, as a result of which to sensitive malfunctions comes. Finally, the leads Use of chemical additives to reduce the drainage in the wire section. Production losses of about 10% are the result. Cause for it are primarily the very hydrophilic properties the polyelectrolytes and in particular the hydrocolloid starch. Also lead economic and ecological reasons In addition, in the two past decades, the specific water needs to lower in the manufacture of paper and cardboard. Was accompanied However, this development of a concentration of inorganic and organic substances in the circulation waters of the paper mills. These contaminated circulating waters limit the efficiency of the additives in addition one.

There the use of starch products in the stock suspension instead of pulp to increase the strength of paper and cardboard economically is advantageous, paper manufacturers are at a substitution of Interested in fibrous materials.

In recently, Past has been trying to use the percentage of starch in paper to increase so-called dual systems. With the designation "Dual" becomes thereby in general, the successive use of oppositely charged chemical additive referred to the pulp suspension. While the original Dual systems only retention systems for improved flocculation, drainage and retention included, today is the use of oppositely charged starch products thus designated. Starch dual systems serve to increase this of starch use up to 10 percent by weight, based on the fiber content in the suspension.

From the EP 1 167 434 A1 a process is known in which a dry mixture of an anionic and a cationic starch is gelatinized together and dosed at one point in the stock suspension. This starch mixture with a slight cationic excess charge can be added in an increased proportion of the stock suspension be led.

Out EP 1 143 068 B1 It is further known to add starch in the form of discrete particulate particles in a starch slurry in a papermaking process comprising the steps of shearing a coagulated pulp suspension and re-coagulating the swelled suspension by adding an aqueous suspension of a microparticulate anionic material. The particulate starch particles consist either of untreated native undigested starch, or precooked and therefore soluble starch, which in a separate manufacturing process consuming a separate enclosure must receive to protect the starch particles from significant dissolution before dewatering.

Furthermore, it is off EP 1 103 565 B1 It is known to use finely divided starch in a papermaking process wherein the starch is degraded in a complicated chemical process, hydrophobically modified and then subjected to a specific crosslinking process.

task The invention is a process for the introduction of starch as Mass additive on the one hand and on the other hand when applying starch in Sprühverfah ren to give to the hand, with an increase in the starch content in the paper for improvement Strength level at high drainage rates and simultaneous Relief of the water cycles is achieved.

The The object is achieved by a Method for introducing starch as a mass additive in the production of paper, cardboard and cardboard solved by that mechanically modified starch in the form of discrete particulate Particles is introduced.

The correspondingly introduced particles are gelatinized only afterwards 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 strength-increasing additive, the amount of introduced Strength be significantly increased. At the Use of cationic starches in the stock suspension was the amount to be introduced due to Umladungserscheinungen limited to a maximum of 2 percent by weight. In the use according to the invention particulate Strengthen is no limit up to an additional amount of about 8 weight percent been found.

Out which follow the main claim subsequent claims preferred embodiments of the invention.

Especially Advantageously, the particulate be bound by filtration in the nonwoven fabric.

The Strength is mechanically modified, it being of particular advantage if the mechanical modification is done by grinding the starch. By The grinding process is an activation of the strength, so that the efficiency across from native untreated starch is significantly increased as an additive to the pulp suspension.

Advantageous can the particulate Strength applied as spray starch become. Ground strengths with reduced gelatinization point as spray strength applied, allow one more effective gelatinization during the paper web drying.

at The production of multi-layered products can be achieved by applying of spray strengths between the layers prevents excessive migration into the individual layers which allows improved ply adhesion.

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

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

• – 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 unverkleisterter starch products instead of dissolved, gelatinized starch to increase the dry strength of paper and cardboard with maximum drainage performance on the basis of the present invention, therefore, because it succeeds:

• - Agglomerationsfrei dispersed sufficiently small particles with
• - structured surface,
• - in the finest distribution on the fibers and fillers
• - to save and
• - to gelatinize during drying.

• 1. 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.
• 2. 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 scharfen Bruchkanten.

In the following, the preparation of particulate starches for use in the present invention is exemplified:

• 1. Native potato starch milled in water: 30 g native potato starch, together with 1 kg of ceramic balls and 270 ml of tap water for 30 min milled for an approach under cooling min ^-1 in a bead mill at 6,600. Grinding modifies the starch to destabilize the crystalline structure of the starch grain.
• 2. Potato starch ground in petroleum ether: Commercially available native potato starch is dried at normal temperature in vacuo, first for several days over phosphorus pentoxide and then over calcium hydride. This material showed a dry content of 99.9% after the dry content determination at 130 ° C. 30 g each of this specially dried potato starch together with 1 kg of ceramic balls (ball diameter about 2 mm) and 270 ml of 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 material to be ground is obtained as follows: Grinding media, regrind and solvent are emptied into a sieve. The part of the ground potato starch, which enters the template with the effluent solvent, can be used immediately after the petroleum ether has evaporated. After evaporation of the solvent from the ball bed on the screen, the loosely adhered to the balls ground potato starch is separated by gently shaking the sieve. This type of grinding leads to grain fragments with sharp breaklines.

Claims (7)

A method of incorporating starch as a bulk additive and spraying in the manufacture of paper, paperboard and cardboard in which the starch is incorporated in the form of discrete particulate particles. characterized in that the starch is mechanically modified. Method according to claim 1, characterized in that that the particulate Strength is bound by filtration in the nonwoven fabric. Method according to claim 1, characterized in that that the mechanical modification by grinding the starch takes place. Method according to one of claims 1-3, characterized that the particulate Strength applied as spray starch becomes. Method according to one of claims 1-4, characterized that at multi-layer products spray strength between the layers or on the layers is sprayed. Method according to one of claims 1-5, characterized in that that the particulate Strength through Grinding starch in water Suspension is processed. Method according to one of claims 1-6, characterized that the particulate Strength through Grinding starch is prepared in anhydrous medium.