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Sizing dispersion

Inactive Publication Date: 2002-07-25
LINDGREN ERIK +4
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

0005] In accordance with the invention it has been surprisingly been found that improved sizing can be obtained with an aqueous dispersion according to the claims. More specifically, the present invention refers to an aqueous dispersion of a sizing agent comprising starch having aromatic g

Problems solved by technology

The charged contaminants has an influence on the sizing efficiency and commonly impairs the sizing performance.
High amounts of charged contaminants such as high contents of salts in the suspension renders a suspension which is increasingly difficult to size, i.e. to obtain a paper with satisfactory sizing properties.
An increased amount of added sizing agent often improve sizing, however, leading to higher costs as well an increased accumulation of sizing agents in the white water.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 2

[0026] In this example the same anionic sizing dispersion was used as in example 1. Furthermore, the same sizing promoter was also used as in example I containing benzyl substituted starch having a DS of 0.065 (5 kg / tonne dry stock) and condensated naphtalene sulphonate (0.120 kg / tonne dry stock) available under the trade name Tamol.RTM.. The anionic sizing dispersion was added to the same cellulosic suspension, however, the conductivity of the suspension was 5000 .mu.S / cm instead of 500 .mu.S / cm.

2TABLE 2 anionic sizing dispersion / [kg sizing agent / tonne Test no. dry stock] cobb 60 / [g / m.sup.2] test 1 0.125 33 test 2 0.140 25

example 3

[0027] The sizing performance of a cationic sizing according to prior art was evaluated using the cobb 60 test. The sizing dispersion was prepared by mixing cationic starch having no aromatic groups and lignosulphonate with molten AKD having an AKD content of 15 weight % based on total dispersion. The papermaking stock contained 85% of 30:30:40 pine:birch:eucaluptus sulphate pulp and 15% of precipitated calcium to which CaCl.sub.2 was added. Stock consistency was 2.5 g / l having a pH of 8.1 and a conductivity of 500 ps. The dispersion was used in conjunction with a retention and dewatering system comprising a cationic aromatic modified starch having a DSc of 0.065 containing bezene groups and condensated naphtalene sulphonate which were added to the stock separately. The cationic aromatic modified starch was added in an amount of 5 kg / tonne, based on dry stock and the condensated naphtalene sulphonate was added in an amount of 0.5 kg / tonne, repectively.

3 TABLE 3 Sizing dispersion add...

example 4

[0028] In this example the conditions, i.e. sizing dispersion, dewatering and retention system, etc. were the same as for example 3, however, the conductivity of the stock was 5000 .mu.s by the addition of CaCl.sub.2.

4 TABLE 4 Sizing dispersion added / [kg AKD / tonne dry stock] Cobb 0, 122 95

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Abstract

An aqueous dispersion of a sizing agent comprising starch having aromatic groups and a condensed sulfonate, wherein the starch contains less than 95 weight % of amylopectin.

Description

[0001] The present invention refers to an aqueous dispersion of a sizing agent comprising starch having aromatic groups containing less than 95 weight % of amylopectine and condensed sulfonate. The invention further encompasses a method for the preparation of an aqueous dispersion and the use of an aqueous dispersion as a stock or surface size.BACKGROUD[0002] Aqueous dispersions or emulsions of sizing agents are used in papermaking in order to give paper and paper board improved resistance to wetting and penetration by various liquids.[0003] Dispersions of sizing agents generally contain an aqueous phase and finely divided particles or droplets of the sizing agent dispersed therein. The dispersions are usually prepared by homogenizing the sizing agent, water insoluble material in an aqueous phase in the presence of a dispersant using high shear forces and fairly high temperatures. Dispersants conventionally used include anionic, amphoteric and cationic high molecular weight polymers...

Claims

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Application Information

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IPC IPC(8): D21H17/29D21H17/47D21H21/16D21H23/76
CPCD21H17/29D21H17/47D21H21/16D21H23/765
Inventor LINDGREN, ERIKFROLICH, STENPERSSON, MICHAELMORGAN, NICHOLASDUNLEAVEY, RUTH
Owner LINDGREN ERIK
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