Compositions: coating or plastic – Coating or plastic compositions – Heterocyclic
Reexamination Certificate
2002-05-08
2004-02-17
Brunsman, David (Department: 1755)
Compositions: coating or plastic
Coating or plastic compositions
Heterocyclic
C106S287260, C162S158000
Reexamination Certificate
active
06692560
ABSTRACT:
The present invention refers to an essentially water-free composition and an aqueous sizing composition comprising a sizing agent, a non-ionic surfactant, an anionic surfactant and a monohydric alcohol. The invention furthermore encompasses the use of such compositions for stock sizing or surface sizing paper or boar and a method of producing an aqueous dispersion.
BACKGROUND
Sizing agents are used in paper and board production in order to obtain products which have enhanced resistance against penetration of aqueous solutions. The sizing agents are not added as such to the pulp suspension but are added in form of emulsions or dispersions. As the sizing agents commonly are hydrophobic, compounds facilitating the formation of a dispersion are present during homogenisation. The homogenisation is effected by mixing the sizing agent, the dispersing agent or agents in the presence of high shear forces which are introduced by using a high-pressure homogenisation equipment.
There exists a huge number of different sizing agents which may be divided into two groups, namely non-cellulose reactive sizing agent and cellulose-reactive sizing agent where the latter are believed to form covalent bonds to the cellulosic fibres. Cellulose-reactive sizing agents do, however, not only react with the cellulosic fibres of the suspension but also interact with aqueous solutions, i.e. the water content of the dispersion, thereby undergoing hydrolysis which eventually effects a decrease of the amount of active cellulose-reactive sizing agent. Accordingly, the stability of aqueous dispersions or emulsions comprising cellulose-reactive sizing agent is thereby limited.
GB 2122656 discloses a sizing composition comprising a carboxylic acid anhydride and a polyoxyalkylene non-ionic surfactant blocked with a lower alkyl, acyl or carbamoyl group and/or an alkaline earth metal of a sulphur containing anionic surfactant.
U.S. Pat. No. 4,376,177 relates to sizing of woven fabric using sizing compounds.
EP 984101 refers to sizing compositions containing a sizing agent and an organic complexing agent.
WO 9749865 discloses ASA sizing emulsions containing a cationic polymer mixture of low molecular weight water-soluble cationic ionene and high molecular weight cationic polyethylene, furthermore, a surfactant is also present in the emulsion.
U.S. Pat. No. 5,059,675 relates to surface sizing compositions containing the reaction product of melamine formaldehyde compounds with long chain saturated or unsaturated alcohol and polyethoxylated alcohol.
One objective of the present invention is, thus, to provide a sizing composition which is easily homogenisable, i.e. a dispersion or emulsion is formed by only introducing minor shear forces such as gentle stirring.
Another objective of the present invention is to provide storage stable sizing compositions.
Further objectives are mentioned hereinafter.
INVENTION
In accordance with the present invention an essentially water-free sizing composition and an aqueous sizing composition has been found comprising a sizing agent, a non-ionic surfactant, an anionic surfactant and a monohydric alcohol. In addition, the present invention also refers to the use of the composition for stock sizing or surface sizing of paper or board and a method for producing an aqueous dispersion comprising homogenising the sizing agent in the presence of a non-ionic surfactant, an anionic surfactant and a monohydric alcohol.
The sizing agent present in the sizing composition may be non-cellulose-reactive agents including rosin, i.e. disproportionated rosin, hydrogenated rosin, polymerised rosin, formaldehyde-treated rosin, esterified rosin, fortified rosin and mixtures of such treatments and so treated rosins, fatty acids and derivatives thereof, e.g. fatty acid esters and amides like bis-stearamide, resin and derivatives thereof, e.g. hydrocarbon resins, resin acids, resin acid esters and amides, waxes, e.g. crude and refined paraffin waxes, synthetic waxes, naturally occuring waxes, etc, and/or cellulose-reactive agents. Preferably, the sizing agent is a cellulose-reactive sizing agent. The cellulose-reactive-sizing, agents comprised in the sizing dispersion can be selected from any cellulose-reactive 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. Preferred ketene dimers have the general formula (I) below, wherein R
1
and R
2
represent saturated or unsaturated non-branched or branched hydrocarbon groups, the hydrocarbon groups suitably having from 8 to 36 carbon atoms, usually being alkyl groups having 12 to 20 carbon atoms, such as hexadecyl and octadecyl groups. In a preferred embodiment the ketene dimers are liquid at ambient temperature, i.e. at 25° C., suitably at 20° C., whereby R
1
and/or R
2
suitably are unsaturated alkyl groups having 12 to 20 carbon atoms, e.g. oleic group, or shorter alkyl groups with from 8 up to 18 carbon atoms. 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 hydro-carbon 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.
The non-ionic surfactant comprised in the composition or dispersion is preferably a polyoxyalkylene compound which may comprise a hydrophobic moiety having at least 8 carbon, notably from 8 carbon atoms and up to 36 carbon atoms. The hydrophobic moiety can contain other atoms than carbon and hydrogen as long as the moiety has an overall hydrophobic character. The hydrophobic moiety can be a branched, non-branched saturated or unsaturated hydrocarbon suitably containing aromatic functionalities such as aromatic ring systems or fused aromatic ring systems said aromatic systems being part of the main hydrocarbon structure or being pendent groups linked to the branched or non-branched main hydrocarbon structure. Preferably, the hydrophobic moiety is a non-branched saturated hydrocarbon chain which may contain from 8 up to 36 carbon atoms, suitably from 10 up to 20 carbon atoms, and most preferably from 10 up to 15 carbon atoms. The polyoxyalkylene compound may contain only one type of repeating alkylene oxide unit or different types of alkylene oxide units exemplified by the formula (1) R
1
O, where R
1
is a hydrocarbon group having 2 to 4 carbon atoms. The polyoxyalkylene compound may have from 2 up to 30 alkylene oxide units of the same type or different types, commonly from 5 up to 10 alkylene oxide units, and preferably from 5 up to 8 alkylen oxide units. Most preferably, the polyoxyalkylene compound contains ethylene oxide and/or propylene oxide units, suitably only ethylene oxide units in an amount of from 5 up to 10 ethylene oxide units, preferably from 5 up to 7 ethylene oxide units. The weight average molecular weight of the polyoxyalkylene compound can be up to 4000, suitably from 200 up to 2300. The polyoxyalkylene compound may be exemplified by the formula (2) R
2
—[—(R
3
O)
n
—]—H, where R
2
is a hydrophobic moiety as defined above, suitably a non-branched alkyl group containing from 8 up to 36 carbon atoms, R
3
is an ethylene group and n an integer from 2 up to 30. Suitably, the polyoxyalkylene compound is selected from the
Holmberg Krister
Leijon Håkan
Mohlin Kristina
Akzo Nobel N.V.
Brunsman David
Burke Michelle J.
Parker Lainie E.
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