FI90679C - Method for controlling the cationicity of ketene dimer dispersions - Google Patents

Description

90679

Method 5 for controlling the cationicity of ketene dimer dispersions 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, as well as resin gluing in which variously modified woods are utilized.

Linen 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, they 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 the temperature of the paper machine 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 with resin adhesives or reacting with glucose units such as OH In connection with AKD and ASA adhesives.

35 The speed of the sizing process depends to a large extent on the paper machine system, such as pH, the quality of the fibrous material and the interaction of other chemicals used in papermaking.

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Resin adhesives are made to adhere to the surface of the fiber, usually by means of alum (aluminum sulfate). Resin sizing thus requires a low pH, 4 to 5, in which alum forms 5 positively charged ions, which in turn bind the resin to the fiber. In so-called pseudoneutral systems, modified resin dispersions at myds neutral pH can be used. In these, alum has been replaced by various cationic polymers which attach -10 vMt to the negatively charged surface of the actual adhesive, resin, fiber.

When the pH in papermaking rises to 6.5 to 9.0, i.e. often when carbonate is used as a filler, the resin adhesives are no longer functional but either AKD or ASA gluing is required. These sizing agents work effectively in 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% up to 20% and up to 30%. The stability of such dispersions is generally good, and this allows them to be prepared outside the paper mill.

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

As the 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 women in the so-called. interfering substances are present in recycled pulp, i.e. deinked pulp and mechanical pulp. The wreckage generated in the production of coated paper returns to the beginning of the paper machine, also increasing the load of interfering substances in 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 reduce the retention of the adhesive component in the paper web. The AKD passing through the wire 15 does not react with the fiber but enters the circulating water, where it, due to its high pH, 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 can improve the retention of the adhesive in AKD gluing and thus enhance the gluing. However, the cationicity of commonly available starches is relatively low, and as the interfering substance contents increase, synthetic organic cationic polymers have to be used. Cationic polymers for enhancing cationicity are commonly referred to in the context of sizing as promoters, i.e., substances that enhance sizing. Such cationic polymers include, for example, polydadmac products, some starch resins, and condensation products of formaldehyde and dicyandiamide. They are all 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 to the paper mill either free of vMlit 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 it is proposed to use cationic starch having a high degree of substitution as a raw material for the sizing. The degree of substitution is mentioned to be in the range of 0.005 to 3. The focus is tertiary modified.

According to the invention, it has been found that the aforementioned highly cationic polymers can be advantageously replaced by highly cationic, long-cleaved observations, which are characteristically prepared according to the invention using quaternary substitution of 2,3-epoxypropyltrimethylammonium-2-chloro-dialoxypropylammonium chloride 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., no promoter-containing dispersions and, respectively, promoter-containing dispersions. High cationic observation, i.e. corresponding analytical values have been established for the charge states obtained by means of the observation 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 space.

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 the promoter.

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High cationic starch (Raifix 220, nitrogen content about 3.7%, cationicity about 2.6 meq / g, viscosity as a 30% aqueous solution about 1000 cP) has been added to dispersions 5 to 6 to provide cationicity. , 3-epoxypropyltrimethylammonium chloride).

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Dispersion no. 80 and 100% of the AKD value.

It can be clearly seen from the examples that high cationic observations can be used in the same way as synthetic cationic polymers to obtain the cationicity of the AKD dispersion.

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Claims (3)

A process for controlling the rate of cationization of an alkyl ketene dimer dispersion by adding to the dispersion a polymer having a high degree of substitution, characterized in that decomposition starch is used, which with quaternary 2,3-epoxypropyl trimethyl ammonium chloride or 3 -chloro-2-hydroxypropyltrimethylammonium chloride has been substituted to the degree of substitution 0.5 -1.0. 30 1. A small amount of alkylyliceneenide dimer dispersion cationic acid dispersion dispersionicone corkean substituutioasteeneofthewall polymeric, thinly-dimethyl-chloromethyl-chloromethyl-3 , 0 substitute, pilkottua tarkkelysta. 10 2. A process according to claim 1, characterized in that starch is used, which is broken down to about 1000 cP viscosity value, as 30% solution. 2. Patenttivaatimuksen 1 mukainen menetelma, tunnettu siita, one kaytetaan turquoise, joka on pilkottu noin viscosettettiarvoon 1000 cP, 30%: na liuoksena. 3. Patent tivaatimuksen 1 tai 2 mukainen menetelma, tun nettu siita, one tarkkelystand kaytetaan 30 - 100% alky-liketeenidimeeriliiman must be allowed. Patent claims: 3. A method according to claim 1 or 2, characterized in that the starch is used at 30 - 100% of the amount of the alkylcendylene adhesive.