FI90679B - Process intended for regulating the degree of cationic polymerization in ketene dimer dispersions - Google Patents

Abstract

In the process according to the invention the degree of cationic polymerization in an alkyl ketene dimer dispersion is regulated by adding broken down starch to the dispersion, which starch has been substituted with 2,3-epoxypropyltrimethyl ammonium chloride or 3-chloro-2- hydroxypropyltrimethyl ammonium chloride to a degree of substitution of 0.5-1.0.

Description

90679

Method for controlling the cationicity of ketene dimer dispersions 5 In papermaking, and in particular in the production of printing paper and liquid packaging board, various sizing chemicals are used to hydrophobize the fibrous material, i.e. to improve the water permeability properties. Examples of hydrophobization chemicals used are aqueous dispersions of AKD wax (alkyl ketene dimer), ASA glue (alkenyl succinic anhydride), and its dispersions, and resin gluing using variously modified wood resins.

Sizing chemicals can be divided into reactive and non-reactive substances. Resin adhesives belong to the so-called non-reactive adhesives, i.e. they do not form a chemical bond with the fibrous material. Their function is based on the fact that they are hydrophobic in themselves and, when precipitated or attached to the fiber, give the desired hydrophobic effect. AKD and ASA adhesives, in turn, are reactive adhesives and react with the OH groups of the cellulosic fiber to form covalent bonds.

Adhesives are generally added to the fiber dispersion just prior to the web forming step. Under the influence of paper machine temperature and other paper machine conditions, such as other auxiliary and auxiliary chemicals, the active component of the adhesive adheres to the fiber, either forming a water-repellent layer on its surface as in resin adhesives or reacting with OH groups of glucose units in the fiber. In the case of AKD and ASA-1 mice.

35 The speed of the sizing process depends as much as possible on the paper machine system, such as pH, the quality of the fibrous material and the interaction of other chemicals used in the manufacture of the paper.

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Resin adhesives are usually attached to the surface of the fiber by means of alum (aluminum sulfate). Resin sizing thus requires a low pH, 4-5, where alum form-5 produces positively charged ions, which in turn bind the resin to the fiber. In so-called pseudoneutral systems, modified resin dispersions can also be used at neutral pH. In these, alum has been replaced by various cationic polymers which adhere the actual adhesive, the resin, to the negatively charged surface of the fiber.

When the pH in papermaking rises to 6.5 to 9.0, i.e. often using carbonate as a filler, resin adhesives are no longer functional but either AKD or ASA gluing is required. These sizing agents work effectively under neutral papermaking conditions where traditional resin adhesives or resin adhesive dispersions are no longer effective.

20 AKD wax can be dispersed with various excipients into dispersions with an active ingredient content ranging from 6% upwards to 20% and 30%. The stability of such dispersions is generally good, and this allows them to be prepared outside the paper mill.

AKD dispersions are commonly prepared using a protective colloid, which is often a low cationic starch (degree of substitution <0.05), and a dispersant. In addition, preservatives, pH adjusting agents and possibly ingredients which have a beneficial effect on the stability of the dispersion are generally used.

As dispersants, generally known anionic, cationic or nonionic dispersing chemicals can be used. The choice depends above all on the intended use of the final product.

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The circulating water of the paper machine contains varying amounts of soluble and colloidal either anionic or nonionic components, depending on the origin of the fibrous materials used. Especially a lot of these so-called. interfering substances are present in the recycled pulp, i.e. deinked pulp and mechanical pulp. The wreckage produced in the production of coated paper returns to the beginning of the paper machine, also increasing the interfering load of the circulating water of the paper machine.

10 Interfering substances adversely affect the gluing process, especially AKD or neutral gluing. They degrade the retention system of the paper machine and thus impair the retention of the adhesive component in the paper web. The AKD passing through the wire does not react with the fiber but enters the circulating water, where due to its high pH it rapidly hydrolyzes to ketone and other gluing inert components, increasing the interference load of the system.

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It is known that the use of low cationic (degree of substitution <0.05) starches in AKD sizing can improve the retention of the sizing agent and thus enhance the sizing. However, the cationicity of commonly available starches is relatively low and synthetic organic cationic polymers have to be used as the concentrations of interfering substances increase. Cationic polymers for increasing cationicity are commonly referred to as promoters in gluing, i.e., agents that enhance sizing. Such cationic polymers include, for example, polydadmac products, some wet strength resins, and condensation products of formaldehyde and dicyandiamide. All of these are characterized by being short-chain, highly water-soluble, and high-charge polymers.

The high cationic synthetic polymers can be added to the AKD adhesive either by the dispersion manufacturer or they can also be added separately at the paper mill either immediately before or after the application of the neutral adhesive.

U.S. Patent No. 3,130,118 describes the preparation of an AKD dispersion useful for paper sizing, in which cationic starch having a high degree of substitution has been proposed as a raw material for the sizing. The degree of substitution is mentioned to be in the range of 0.005 to 3. The starch is tertiary modified.

According to the invention, it has been found that the above-mentioned highly cationic polymers can advantageously be replaced by highly cationic, highly cleaved starches, which are characteristically prepared according to the invention using quaternary 2,3-epoxypropyltrimethylammonium chloride or 3-chloro-2-hydroxymonium trimethyltrimethyltrimethyltrimethyltrimethyltrimethyltrimethyltrimethyltrimethyl is 0.5 to 1.0.

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Examples have been used to illustrate the invention in which the cationic charge of the AKD dispersion has been measured with a Miitek flow potential detector. As exemplary dispersions, so-called prior art, i.e., non-promoter-containing dispersions and promoter-containing dispersions, respectively. High cationic starch, i.e. corresponding analytical values have been established for the charge states obtained by means of the starch according to the invention.

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Examples: AKD dispersions show dry matter (k.a.) and charge as measured by a Miitek titrator (meq / g).

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Dispersion k.a. (%) AKD pit. Var. volume% meq / g I. 7.5 6.0 0.01 10 2. 13.7 10.0 0.02 3. 11.5 10.0 0.02 4. 15.0 6.0 1.90 5. 15.1 10.0 0.46 6. 11.0 7.7 0.62 15 7. 11.0 5.5 1.33 8. 11.0 5.0 2.58

Dispersions 1-3 do not contain promoters, i.e. cationic polymers. Dispersions have been prepared according to the article, "Das Papier, 39, 5, 1985; J. Mertz, P. Rohringer, M. Bernheim".

Non-accelerated, non-promoter-containing dispersions are characterized by a low charge state.

Dispersions 4-8 are promoter-containing, i.e. accelerated dispersions. The promoted dispersions are characterized by a high cationic state of charge compared to conventional dispersions.

Dispersion 4 has been prepared according to the article, "Pin Journal, II, 1990. p. 140; J. Marton". A synthetic cationic polymer has been used as a promoter.

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High cationic starch (Raifix 220, nitrogen content about 3.7%, cationicity about 2.6 meq / g, viscosity in 30% aqueous solution about 1000 cP) has been added to dispersions 5-6 to provide cationicity. Starch 40 is cationized with 2,3-epoxypropyltrimethylammonium chloro - ridilla).

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Dispersion No. 5 is prepared as Dispersion No. 2, but additionally containing 30% of the amount of AKD in Raifix 220. Dispersions 6 to 8 are prepared as Dispersion 3, but containing high cationic starch, Raifix 220, 30, 80 and 100%, respectively. The amount of AKD.

It can be clearly seen from the examples that high cationic starches can be used, like synthetic cationic polymers, to control the cationicity of an AKD dispersion.

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Claims (3)

7 90679 1. A process for the regeneration of cationic dispersion hosts an alkyl ketide dispersion genome which comprises a dispersion of a polymer having some substitution, which can be obtained by regulating an intermediate of starch with a quaternary 2,3-epoxypropyl ester. or 3-chloro-2-hydroxypropyltrimethylammonium chloride substitution substitutions 0.5 -1.0. 30 A process for adjusting the cationicity of an alkyl ketene dimer dispersion with a polymer having a high degree of substitution added to the dispersion, characterized in that the adjustment is carried out using quaternary 2,3-epoxypropyltrimethylammonium chloride or 3-chloro-2-hydroxypropylenedioxyanthyltrimethylammonium .0 substituted, cleaved starch. 10 Process according to Claim 1, characterized in that starch which has been broken down to a viscosity of approximately 1000 cP is used as a 30% solution. Process according to Claim 1 or 2, characterized in that 30 to 100% of the amount of alkyl ketene dimer adhesive is used from the starch. 20 Patentkrav: 2. A patent according to claim 1, which comprises a starch having a viscosity value of about 1000 cP, with a solution of 30%. 35 3. A patent according to claim 1 or 2, which comprises 30 to 100% of alkylated tendon compounds.