Compositions: coating or plastic – Coating or plastic compositions – Phosphorus or nitrogen containing
Reexamination Certificate
2001-12-21
2002-11-26
Niland, Patrick D. (Department: 1714)
Compositions: coating or plastic
Coating or plastic compositions
Phosphorus or nitrogen containing
C106S287230, C106S287250, C106S287290, C162S164600, C162S158000, C162S135000, C162S164100, C162S167000
Reexamination Certificate
active
06485555
ABSTRACT:
The present invention relates to sizing of paper and more specifically to substantially water-free compositions and aqueous compositions of cellulose-reactive sizing agents, their preparation and use.
BACKGROUND
Cellulose-reactive sizing agents, such as those based on alkyl ketene dimer (AKD) and alkenyl succinic anhydride (ASA), are widely used in papermaking at neutral or slightly alkaline stock pH's in order to give paper and paper board some degree of resistance to wetting and penetration by aqueous liquids. Paper sizes based on cellulose-reactive sizing agents are generally provided in the form of dispersions containing an aqueous phase and finely divided particles or droplets of the sizing agent dispersed therein. The dispersions are usually prepared with the aid of dispersing agents consisting of an anionic compound, e.g. sodium lignosulfonate, preferably in combination with a high molecular weight amphoteric or cationic polymer, e.g. cationic starch, polyamine, polyamideamine or a vinyl addition polymer. However, dispersions of these types usually exhibit rather poor stability and high viscosity, even at relatively low solids contents, which evidently lead to difficulties in handling the dispersions, for example on storage and in use. A further drawback is that the products have to be supplied as low concentration dispersions which further increases the costs of transportation of the active sizing agent as well as the cost for storage due to the large volume occupied by the aqueous content of common dispersions.
U.S. Pat. No. 5,176,748 refers to a sizing composition containing ASA, a cationic soluble dispersing agent and optionally a non-ionic surfactant. The cationic dispersing agents used are high molecular cationic dispersing agent such as diallyl dimethyl ammonium chloride (Polydadmac) having molecular weights of around 50,000.
EP 220941 A1 relates to a solid composition comprising ketene dimers, an encapsulating agent such as polyethers and a cationic polymer such as polyamines.
U.S. Pat. No. 4,743,303 discloses aqueous dispersions of rosin and synthetic sizing agents comprising non-ionic surface active agents and cationic dispersing agents.
EP 707110 A1 relates to an alkenylsuccinic emulsion sizing agent comprising an emulsifier and/or an anionic high-molecular weight stabiliser.
Before usage of the compositions they are emulsified in the presence of an aqueous phase. In order to reduce the particle size shear forces are required. One advantage of the present invention is therefore to improve emulsification/dispersing properties. Yet another advantage of the present invention is to achieve good and/or improved sizing while using a substantially water-free sizing composition which disperses easy/fast in an aqueous phase. Furthermore the problem of stability relating to the usual sizing dispersions is circumvented by providing a sizing composition which is essentially water-free. Further objects will appear hereinafter.
The Invention
In accordance with the present invention it has been found that improved homogenisation can be obtained with an essentially water-free composition according to the claims. More specifically, the invention relates to an essentially water-free composition of a cellulose-reactive sizing agent comprising a non-ionic compound and a cationic compound with a molecular weight of up to 10,000 which are effective as dispersing agents. The size compositions of this invention are easily homogenised thus minimising the use of shear forces. In addition, the present invention relates to an aqueous composition of a cellulose-reactive sizing agent and their preparation and use, as further defined in the claims.
The present composition makes it possible to reduce transportation costs by virtually excluding the amount of water usually present in dispersion. The present invention thus offers substantial economic and technical benefits.
By aqueous composition is also meant an aqueous dispersion of a cellulose reactive sizing agent. Accordingly, an aqueous dispersion or an aqueous composition is obtained by emulsification or homogenisation of the substantially water-free composition of a sizing agent.
The cellulose-reactive sizing agent according to the invention can be selected from any of the cellulose-reactive sizing agents known in the art. Suitably the sizing agent is selected from the group consisting of hydrophobic ketene dimers, ketene multimers, acid anhydrides, organic isocyanates, carbamoyl chlorides and mixtures thereof, preferably ketene dimers and acid anhydrides, most preferably ketene dimers. Suitable ketene dimers have the general formula (I) below, wherein R
1
and R
2
represent saturated or unsaturated hydrocarbon groups, usually saturated hydrocarbons, the hydrocarbon groups suitably having from 8 to 36 carbon atoms, usually being straight or branched chain alkyl groups having 12 to 20 carbon atoms, such as hexadecyl and octadecyl groups. Suitable acid anhydrides can be characterized by the general formula (II) below, wherein R
3
and R
4
can be identical or different and represent saturated or unsaturated hydrocarbon groups suitably containing from 8 to 30 carbon atoms, or R
3
and R
4
together with the —C—O—C— moiety can form a 5 to 6 membered ring, optionally being further substituted with hydrocarbon groups containing up to 30 carbon atoms. Examples of acid anhydrides which are used commercially include alkyl and alkenyl succinic anhydrides and particularly isoocta-decenyl succinic anhydride.
Suitable ketene dimers, acid anhydrides and organic isocyanates include the compounds disclosed in U.S. Pat. No. 4,522,686, which is hereby incorporated herein by reference. Examples of suitable carbamoyl chlorides include those disclosed in U.S. Pat. No. 3,887,427 which is also incorporated herein by reference.
In addition to the cellulose-reactive sizing agent, the size dispersions may also contain a non-cellulose-reactive sizing agent. Examples of suitable sizing agents of this type include rosins, e.g. fortified and/or esterified rosin, waxes, fatty acid and resin acid derivatives, e.g. fatty amides and fatty esters, e.g. glycerol triesters of natural fatty acids.
The cationic compound comprised in the present invention preferably contains one or more cationic groups of the same or different types and include cationic compounds having one cationic group and cationic compounds having two or more cationic groups, i.e. cationic polyelectrolytes. Examples of suitable cationic groups include sulfonium groups, phosphonium groups, acid addition salts of primary, secondary and tertiary amines or amino groups and quaternary ammonium groups, for example where the nitrogen has been quaternized with methyl chloride, dimethyl sulfate or benzyl chloride, preferably acid addition salts of amines/amino groups and quaternary ammonium groups. Cationic polyelectrolytes can have a degree of substitution varying over a wide range; the degree of cationic substitution (DS
C
) can be from 0.01 to 1.0, suitably from 0.1 to 0.8 and preferably from 0.2 to 0.6.
Suitable cationic organic compounds for use in this invention include cationic compounds capable of functioning as a surfactant and/or dispersing agent. Preferably the cationic compound is a surfactant. The cationic surfactant can be selected from primary, secondary, tertiary, and quaternary ammonium compounds containing at least one hydrocarbon group with from 9 to 30 carbon atoms. Further preferred cationic surfactants include compounds having the general formula R
4
N
+
X
−
, wherein each R group is independently selected from (i) hydrogen; (ii) hydrocarbon groups, suitably aliphatic and preferably alkyl groups, having from 1 to about 30 carbon atoms, preferably from 1 to 22 carbon atoms; and (iii) hydrocarbon groups, suitably aliphatic and preferably alkyl groups, having up to about 30 carbon atoms, preferably from 4 to 22 carbon atoms, and being interrupted by one or more heteroatoms, e.g. oxygen or nitrogen, and/or groups containing a heteroatom, e.g. carbonyl and acyloxy groups; where
Frölich Sten
Lindgren Erik
Sikkar Rein
Akzo Nobel N.V.
Niland Patrick D.
Parker Lainie E.
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