FI94535C - Process for preparing a hydrophobic dispersion - Google Patents

Abstract

The present invention relates to a process for the preparation of hydrophobic sizing agent dispersions used in the paper and board industry. The invention is both a simple and an economical way of preparing a hydrophobic sizing agent dispersion either in the premises of a sizing agent supplier or a paper maker. The invention is based on a usage of a so-called high-pressure digester in the preparation of a hydrophobic sizing agent dispersion.

Description

...... 94535

Hydrophobic dispersion preparation process - Process for the production of hydrophobic dispersion

By hydrophobic gluing is meant making the paper or board 5 more or less water-repellent. This property can be measured, for example, by the so-called Cobb test, which measures the penetration of water into paper or board as a function of time. The result is expressed as absorption in g / m2. A properly hydrophobically bonded product will generally have a value of <25 g / m2 10 while a product that has not been treated with hydrophobic adhesives may have a value of> 100 g / m2.

Conventional compounds used as hydrophobic adhesives include wood-derived rosin acids and their derivatives.

Today, the paper and board industry has increasingly switched to the use of so-called neutral adhesives for hydrophobic sizing, which are usually alkyl ketene dimer (AKD) -20 or alkenyl succinic anhydride (ASA) -based compounds.

Hydrophobic adhesives are usually supplied to paper or board mills as an aqueous dispersion in which the proportion of active substance (AKD, ASA, 25 resin) in the product is between 5 and 50%. In the case of an ASA type adhesive, the adhesive dispersion is prepared:. mainly at a paper or board mill.

• · · · 94535 is used e.g. cationic starch, cationic polyethyleneimines, cationic polyacrylamides, gelatin or casein.

5 As surfactants, e.g. sodium lignosulfonate or alkyl sulfonates.

Typical additional chemicals include biocides, alum and pH adjusting chemicals.

10

A common way to prepare a hydrophobic adhesive dispersion of these components in a reactor is to prepare, by stirring and heating, a homogeneous premix containing the appropriate proportions of water, active ingredient, stabilizer, surface-active agents, and any additional chemicals.

Once a homogeneous premix is obtained, this is generally recycled through a high pressure homogenizer, colloid mill, or high speed centrifugal pump 20 more times until a sufficiently small particle size is obtained (usually 0.1 to 10 μιη). The pressure varies between 50 and 500 bar and the temperature between 50 and 100 ° C. The dispersion obtained is then passed through a heat exchanger to the product tank. In the heat exchanger, the dispersion temperature is lowered to <25 to 30 ° C. Processes that follow these principles are pictorial; tu mm. in EP-353 212 and EP-369 328.

»·« · · 4 · * «· · ·

It has now surprisingly been found that a high-pressure cooker (steam cooker or so-called jet cooker) designed mainly for starch cooking acts as a very good dispersant in the preparation of a hydrophobic glue dispersion. The complete steam jet process works as follows: • · · • · ·. The premix is prepared in reactor 1 according to the same principle 35 as in the above process. The mixture is then pumped into the boiler section 2 itself, where the mixture meets the high-pressure steam stream 3, and the temperature and pressure rise (pressure 3 94535 usually 2-15 bar and temperature 100-200 ° C). The resulting dispersion is then passed to a tubular reactor 4, after which the pressure and temperature are lowered in the evaporator device 5 and the excess steam can be separated by a steam-5 condenser 6. The homogeneous product formed is then passed through a heat exchanger to the product tank.

The flow of the process is shown schematically in the accompanying drawing.

10 This process differs from the traditional process as follows:

Traditional process 15

Pressure 50 - 500 bar temp. 50-100 ° C

Steam jet cooker process 20

Pressure 2-15 bar temp. 100-200 ° C

25 The preparation of a hydrophobic adhesive dispersion in a steam jet boiler type process allows the use of high dry solids during processing and because the delay in the boiler and reaction tube is very short, usually • <2 minutes this allows the use of very small units with high ready- • '/ :. The pain capacity.

»·« ... Eg 1 »* i

On a laboratory scale, a premix of stearin / palmitin alkyl ketene dimer (AKD) with the following composition was prepared: water 800 g AKD 200 g 40 Orota SN * 3.0 g: Raisamyl 150E ** 22 g 4 94535 * Naphthalene formaldehyde sulfonate condensate, sodium ** Cationic potato starch (DS = 0.05).

5 The starch was boiled before addition.

This premix was divided into two portions, one of which was run 3 times through a laboratory high pressure homogenizer (Rannie). Pressure 200 bar, temperature 70 ° C. The other 10 parts were passed through a laboratory-scale steam jet cooker once, temperature 120 ° C, pressure 3 bar. Both emulsions were diluted to 12.5% dry matter and cooled to room temperature.

The following properties, viscosity (Brookfield) and average particle size were measured for both dispersions.

High-pressure steam jet 20 homogenizer cooker

Viscosity 10 cP 8 cP

Mean 2 5 particle size 0.56 Mm 0.60 μν \ • · • · • · • ♦ ♦ • · * «· ·«: The results show that the dispersions have almost identical properties: * ·.

• · 30 • · ·

The dispersions were kept at room temperature for one month .. '. M and the same measurements were performed again with the following result.

5,94535

High-pressure steam jet homoenizer cooker

5 Viscosity 15 cP 16 cP

Mean particle size 0.86 μm 0.95 μm 10 The results show that the storage stability of both dispersions is of the same order.

Example 2 A premix of alkenyl succinic anhydride (ASA) having the following composition was prepared on a laboratory scale.

water 900 g 20 ASA 50 g

Orotan SN 0.5 g

Raisamyl 150E 100 g * Anhydrides derived from straight chain C13 to C20 alpha-olefins were used as alkenyl succinic anhydride.

This premix was again divided into two parts, one of which: Λ was passed through a high-pressure homogenizer (pressure 200 bar • 30 temperature 50 ° C) and the other through a steam jet cooker (temperature 110 ° C and pressure 1.5 bar).

• · · · • · t t 1 • «1

The resulting dispersions were diluted to 7.5% dry matter and measured for viscosity and mean particle size.

35 »· t • · ·» · «· 6 94535

High pressure- Hövrvsuiku- homocrenizer cooker

5 Viscosity 600 cP 520 cP

The average particle size is 0.50 μm 0.65 μm 10

The results show that the dispersions are almost similar. A value of <1 μιη is generally considered to be a good particle size in this type of product.

15 • «· • · • · * · 1

Il. . Utit joined 1: 1 1 4 * - - t · · • · · «·

Claims (2)

94535 1. For the production of hydrophobic compounds, such as the alkylation process, which are treated with alkenyl stearic anhydride (ASA), or alkyl alkyl endorses (25), the basic components of which are present in the same ... ... denied ·: Ning och omröring av en limförblandning, och denna • · l. '·· blandning utsättes för en värme- och mechanan behandling::: ett. tryck at 2 - 15 bar and at a temperature of 100 - 2 00 ° C, «« ·. ··. ·. under en tid under 2 minuter. • · ♦ A process for preparing a hydrophobic adhesive, in particular for a papermaking process, wherein an alkyl mer-5-succinic anhydride (ASA) or alkyl ketene dimer (AKD) -based adhesive base component and preferably added additives are prepared by heating and mixing the adhesive premix and subjecting the adhesive premix thereto, and treatment to obtain an adhesive dispersion, characterized in that the pressure treatment is carried out at a pressure of 2 to 15 bar and a temperature of 100 to 200 ° C, in less than 2 minutes. Method according to Claim 1, characterized in that the pressurized treatment is carried out by subjecting the adhesive premix to high-pressure water vapor applied at a high speed. 20 Patentkrav: 2. A patent according to claim 1, which is defined as 35, is used for the purpose of limiting the genome: