Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Patent
1995-01-06
1997-05-06
Smith, Jeffrey T.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
524437, 524548, 524555, C08K 310
Patent
active
056272243
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to water based compositions of synthetic cellulose-reactive sizing agents, which are alkyl ketene dimers or cyclic dicarboxylic acid anhydrides and more particularly to such compositions which contain an amphoteric polymer and a polyaluminium compound.
Alkyl ketene dimers (AKD) and cyclic dicarboxylic acid anhydrides, particularly alkenyl succinic anhydride (ASA), are to a great extent used for paper sizing, hydrophobing, at neutral or alkaline pH. The compounds are cellulose reactive and bind directly to the hydroxyl groups in the cellulose. The commercially used products are usually stabilized with cationic starch which also contributes to retention of the sizing agent. Separate additions of retention agents and other chemicals to the stock are often also used to increase retention and to improve the sizing. It is known to use the sizing agents in combination with aluminium compounds. Small amounts of alum are often used for ASA-emulsions, either in the emulsion or as separate stock addition, primarily to decrease the deposition problems which are connected with this. The production of sized paper by stock addition of cationic AKD-dispersion, high cationized starch and water soluble aluminium salt is described in the Japanese patent application 84-199900. It is also known from the German patent application 4090740 to incorporate a polyaluminium compound in dispersions of AKD and cationic dispersing agent such as cationic starch. D-based sizing compositions are comparatively expensive due to the costs for the ketene dimer as such and the development is thus directed to production of dispersions which give the best sizing with the lowest amount of AKD. Requirements are of course also made on the dispersions as such with regard to stability and satisfactory high dry contents.
According to the present invention it has been found that water based compositions of ketene dimers or cyclic dicarboxylic acid anhydrides which comprise both an amphoteric polymer and a polyaluminium compound give very good sizing with low amounts of the sizing agent since they give good retention of this and since they also positively contribute to general retention of fibres and fillers and to dewatering effect at paper production. They also have good effect in the presence of retention/dewatering systems which are based on anionic inorganic colloids, such as silica based colloids, and cationic polymers.
The present invention thus relates to aqueous compositions of sizing agents which are hydrophobing cyclic dicarboxylic acid anhydrides or alkyl ketene dimers, which compositions comprise an amphoteric polymer, which is amphoteric starch or an amphoteric acrylamide based polymer, and a polyaluminium compound.
The two types of sizing agents are per se well known. Cyclic dicarboxylic acid anhydrides can be characterized by the general formula ##STR1## wherein R.sub.2 is a dimethylene or trimethylene radical and R.sub.1 is a hydrocarbon group having more than 7 carbon atoms and can be an alkyl, alkenyl, aralkyl or aralkenyl group. The cyclic dicarboxylic acid anhydrides which are used commercially to the greatest extent are alkyl and alkenyl succinic anhydrides (ASA) and particularly isooctadecenyl succinic anhydride.
Alkyl ketene dimers have the general formula ##STR2## wherein R.sub.1 and R.sub.2 are hydrophobic hydrocarbon groups having about 6 to about 30 carbon atoms and which are usually alkyl groups having 12 to 20 carbon atoms, such as hexadecyl and octadecyl groups.
The amphoteric polymer in the present compositions are amphoteric starch or amphoteric acrylamide based polymer. The term amphoteric herein refers to polymers containing both anionic and cationic groups. Amphoteric starch is preferred and for this the anionic groups can for example be phosphate, phosphonate, sulphate, sulphonate or carboxylic acid groups and they are preferably phosphate groups. The cationic groups are tertiary amino groups or quaternary ammonium groups. The ratio between the number of anionic and cationic groups in the
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Hernandez, H.R., "Amphoteric Waxy Maize Starch use in Alkaline Papers" EUCEPA 24.sup.th Cont. Proc. (Stockholm), Pap Technol.: 186-195 (May 8-11, 1990).
Hernandez, H.R., "Amphoteric Waxy Maize Starch Use In Alkaline Papers", EUCEPA 24th Cont. Proc. (Stockholm), Pap. Technol.: 186-195, May 8-11, 1990.
International Search Report for International Application No. PCT/SE 93/00541.
Carr e Bruno
Lyrmalm Ebbe
Eka Nobel AB
Mancini Ralph J.
Morris Louis A.
Smith Jeffrey T.
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