Compositions: coating or plastic – Coating or plastic compositions – Carbohydrate or derivative containing
Reexamination Certificate
1999-04-16
2001-02-06
Brunsman, David (Department: 1755)
Compositions: coating or plastic
Coating or plastic compositions
Carbohydrate or derivative containing
C106S210100, C106S213100, C106S214100, C106S214200, C106S215200, C106S215100, C106S287200, C106S287210, C106S287230, C106S287240, C106S287250, C106S287280, C106S287290, C106S287300, C162S158000, C162S175000
Reexamination Certificate
active
06183550
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to aqueous size dispersions, to methods for making sized paper utilizing the dispersions, and to paper prepared by the methods.
BACKGROUND OF THE INVENTION
Cellulose-reactive and cellulose non-reactive sizes are used widely for sizing paper during its manufacture. Because these sizes are most frequently water-insoluble, they are generally used in the form of aqueous dispersions so that they can be readily handled in the aqueous paper making environment.
Surfactants, i.e., materials typically containing both oil soluble hydrocarbon chains and water soluble polar groups, are generally not used as dispersants for paper size dispersions because they tend to exhibit an anti-sizing effect, i.e. they reduce water resistance. Conventional surfactants generally have one hydrophilic group and one hydrophobic group. Recently a class of surfactants having at least two hydrophobic groups and at least two hydrophilic groups has been introduced. These have been found to be unexpectedly effective when compared to conventional surfactants (Rosen, M. J.,
Chemtech,
March, 1993, pp. 30-33; and Menger, F. M. & Littau, C. A.,
J. Am Chem. Soc.,
1993, 115, pp. 10083-10090). These have become known in the literature as “gemini surfactants”.
Gemini surfactants are disclosed in U.S. Pat. Nos. 5,643,864, 5,710,121, 5,789,371, 5,811,384 and 5,863,886, the disclosures of all five of which are hereby incorporated herein by reference in their entireties. Further examples of gemini surfactants are disclosed in International Publication Nos. WO 95/19955, WO 98/15345, WO 98/15346, WO 98/23365, WO 98/37062 and WO 98/45308.
SUMMARY OF THE INVENTION
It has now been found that gemini surfactants, and certain other surfactants, are especially effective for preparing dispersions of paper sizing compounds, even when used at very low levels, providing size dispersions that produce paper with unexpectedly high sizing properties.
In one embodiment this invention relates to aqueous dispersions comprising: a) at least one paper sizing compound, and b) a water-soluble dispersant containing two or more hydrophilic groups and at least one hydrophobic group. In a preferred embodiment the water-soluble dispersant comprises a gemini surfactant containing two or more hydrophilic groups and two or more hydrophobic groups.
In another embodiment the invention relates to aqueous paper size dispersions comprising: a) a cellulose-reactive sizing agent, and b) a water-soluble dispersant comprising a di- or polyquaternary amine containing at least one hydrophobic group having from about 10 to about 30 carbon atoms.
In a yet another embodiment the invention relates to a process for preparing sized paper comprising: a) providing an aqueous paper making pulp suspension; b) sheeting and at least partially drying the aqueous pulp suspension to obtain paper; c) applying to the surface of the paper an aqueous dispersion comprising at least one paper sizing compound and a water-soluble dispersant containing at least two hydrophilic groups and at least one hydrophobic group; and d) drying to obtain sized paper. It also relates to a process for preparing sized paper comprising: a) providing an aqueous paper making pulp suspension; b) adding to the aqueous pulp solution an aqueous dispersion comprising at least one paper sizing compound and a water-soluble dispersant containing at least two hydrophilic groups and at least one hydrophobic group; and c) sheeting and drying the aqueous pulp suspension of step (b) to obtain sized paper. In yet another embodiment the invention relates to sized paper prepared by these processes.
DETAILED DESCRIPTION OF THE INVENTION
The compositions of the invention are aqueous dispersions comprising at least one paper sizing compound and a water-soluble dispersant that is a surfactant containing at least two hydrophilic groups and at least one hydrophobic group. The surfactants of the invention are water soluble and form micelles when dissolved in water above the critical micelle concentration.
Hydrophilic groups are the groups in the surfactant that promote water solubility. Hydrophobic groups are those that distort the structure of the water in which the surfactant is dissolved, and cause micelle formation and adsorption of the surfactant at the interfaces of the system. Hydrophobic groups are often alkyl or perfluoroalkyl chains.
Paper Sizing Compounds
Preferred paper sizing compounds for the invention are selected from the group consisting of cellulose reactive paper sizing compounds and cellulose non-reactive paper sizing compounds. For the purposes of this invention cellulose-reactive sizes are defined as those sizes capable of forming covalent chemical bonds by reaction with the hydroxyl groups of cellulose, and cellulose non-reactive sizes are defied as those that do not form these covalent bonds with cellulose.
Preferred cellulose-reactive sizes for use in the invention include ketene dimers and multimers, alkenylsuccinic anhydrides, organic epoxides containing from about 12 to 22 carbon atoms, acyl halides containing from about 12 to 22 carbon atoms, fatty acid anhydrides from fatty acids containing from about 12 to 22 carbon atoms and organic isocyanates containing from about 12 to 22 carbon atoms.
Preferred ketene dimers and multimers are materials of formula (1), wherein n is an integer of 0 to about 20, R and R″, which may be the same or different, are saturated or unsaturated straight chain or branched alkyl or alkenyl groups having 6 to 24 carbon atoms; and R′ is a saturated or unsaturated straight chain or branched alkylene group having from about 2 to about 40 carbon atoms.
Ketene dimers for use in the process of this invention have the structure of formula (1) where n=0 and the R and R″ groups, which can be the same or different, are hydrocarbon radicals. Preferably the R and R″ groups are straight chain or branched alkyl or alkenyl groups having 6 to 24 carbon atoms, cycloalkyl groups having at least 6 carbon atoms, aryl groups having at least 6 carbon atoms, aralkyl groups having at least 7 carbon atoms, alkaryl groups having at least 7 carbon atoms, and mixtures thereof. More preferably, ketene dimer is selected from the group consisting of (a) octyl, decyl, dodecyl, tetradecyl, hexadecyl, octadecyl, eicosyl, docosyl, tetracosyl, phenyl, benzyl, &bgr;-naphthyl, and cyclohexyl ketene dimers, and (b) ketene dimers prepared from organic acids selected from the group consisting of montanic acid, naphthenic acid, 9,10-decylenic acid, 9,10-dodecylenic acid, palmitoleic acid, oleic acid, ricinoleic acid, linoleic acid, eleostearic acid, naturally occurring mixtures of fatty acids found in coconut oil, babassu oil, palm kernel oil, palm oil, olive oil, peanut oil, rape oil, beef tallow, lard, whale blubber, and mixtures of any of the above named fatty acids with each other. Most preferably ketene dimer is selected from the group consisting of octyl, decyl, dodecyl, tetradecyl, hexadecyl, octadecyl, eicosyl, docosyl, tetracosyl, phenyl, benzyl, &bgr;-naphthyl, and cyclohexyl ketene dimers.
Alkyl ketene dimers have been used commercially for many years and are prepared by dimerization of the alkyl ketenes made from saturated, straight chain fatty acid chlorides; the most widely used are prepared from palmitic and/or stearic acid. Neat alkyl ketene dimer is available as Aquapel® 364 sizing agent from Hercules Incorporated, Wilmington, Del. Aqueous dispersions of these materials are available as Hercon® paper sizing agents from Hercules Incorporated, Wilmington, Del.
Preferred ketene multimers for use in the process of this invention have the formula (1) where n is an integer of at least 1, R and R″, which may be the same or different, are saturated or unsaturated straight chain or branched alkyl or alkenyl groups having 6 to 24 carbon atoms, preferably 10 to 20 carbon atoms, and more preferably 14 to 16 carbon atoms, and R′ is a saturated or unsaturated straight chain or branched alkylene group having from 2 to 40 c
Conner Herbert
Lin Tingdong
Tuin Gert
van de Steeg Henrica G. M.
Brunsman David
Hercules Incorporated
Sloan Martin F.
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