Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1999-04-16
2001-07-31
Acquah, Samuel A. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S073000, C524S047000, C524S437000, C162S158000, C162S163000, C162S179000
Reexamination Certificate
active
06268414
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to paper sizing compositions containing a) sizing agent, b) dispersant system, and c) inorganic salt, and also to methods of sizing paper using such compositions, and to products made using such sizing compositions.
2. Background of the Invention
Cellulose-reactive sizing agents, such as alkyl ketene dimers (AKDs), are widely used in the paper making industry as components in sizing dispersion formulations. The usefulness of such agents derives from their ability to bond directly to the hydroxyl groups on the cellulose component of the paper. Frequently, in these sizing formulations, the sizes, e.g., AKDs, are combined with dispersant systems which include cationic starch and/or sodium lignosulfonate. Examples of such dispersions can be found in U.S. Pat. No. 4,861,376, to Edwards, and U.S. Pat. No. 3,223,544, to Savina, the disclosures of which are hereby incorporated by reference.
The usefulness of inorganic salts such as alum, or aluminum containing salts, in paper making processes has also been known for some time. Practically, these salts greatly improve machine productivity by enhancing dewatering. As a general rule, the higher the concentration of the salts, the better the dewatering capacity.
The combination of organic sizing agents such as AKD dispersions and inorganic salts such as alum is thus a valuable combination, providing both sizing and dewatering capacity. Examples of such combinations are presented in U.S. Pat. No. 5,145,522 to Nakagawa et al. and U.S. Pat. No. 5,627,224, to Lyrmalm et al., the disclosures of which are hereby incorporated by reference. The problem encountered by this combination, however, is that organic sizing agents tend to be quite incompatible with inorganic salts, separating out if the concentration of the inorganic salts becomes too high in a liquid phase of the organic sizing dispersion.
There is, therefore, a need in the art for a dispersant system which is compatible with inorganic salts and organic sizing agents. A number of dispersant systems have been described in the literature. For example, in U.S. Pat. No. 5,627,224, an amphoteric polymer is used as the sole dispersant to incorporate polyaluminum compounds in dispersions of AKD. However, achieving good stability in compositions containing organic sizes and inorganic salts has been elusive. Thus, there is a need in the art for compositions which solve the aforementioned problems.
SUMMARY OF THE INVENTION
In view of the foregoing, it is an object of the present invention to provide sizing dispersions with improved stability.
It is a further object of the present invention to provide sizing dispersions which enhance dewatering capacity.
It is a further object of the present invention to provide sizing dispersions which comprise organic sizing agent, and inorganic salt in varying concentrations, including high inorganic salt concentrations.
The present invention is also directed to compositions comprising (a) cellulose-reactive size, (b) dispersant system comprising primary dispersant and secondary dispersant, and (c) inorganic salt, to methods of producing and using said compositions, as well as products including the composition.
The present invention is achieved by the provision of an aqueous composition comprising cellulose-reactive size, dispersant system comprising anionic dispersant and at least one cationic dispersant or non-ionic dispersant; and at least one salt comprising an element in an amount equivalent to, or greater than, about 5.5 wt % aluminum, based on the weight of cellulose-reactive size. In preferred embodiments, the cellulose-reactive size comprises at least one of ketene dimer and ketene multimer; more preferably the ketene dimer comprises at least one of alkenyl ketene dimer and alkyl ketene dimer. In other preferred embodiments, the cellulose-reactive size comprises at least one of alkenyl succinic anhydride and stearic anhydride.
The cellulose-reactive size may comprise organic epoxide containing from about 12 to about 22 carbon atoms, acyl halide containing from about 12 to about 22 carbon atoms, fatty acid anhydride from fatty acid containing from about 12 to about 22 carbon atoms, or organic isocyanate containing from about 12 to about 22 carbon atoms.
Preferably, the composition comprises a ketene dimer or ketene multimer of Formula
where n is an integer of from 0 to about 20, R and R
2
are the same or different and are saturated or unsaturated hydrocarbyl groups having from about 6 to about 24 carbon atoms, and R
1
is a saturated or unsaturated hydrocarbyl group having from about 2 to about 40 carbon atoms. Preferably, n has a value of from 0 to about 6; more preferably, n is from 0 to about 3; and most preferably, wherein n is 0. R may be a saturated or unsaturated hydrocarbyl group having from about 10 to 20 carbon atoms; preferably, R is a saturated or unsaturated hydrocarbyl group having from about 14 to 16 carbon atoms. R
2
is preferably a saturated or unsaturated hydrocarbyl group having from about 10 to 20 carbon atoms; more preferably, R
2
is a saturated or unsaturated hydrocarbyl group having from about 14 to 16 carbon atoms. Preferably, R
1
is a saturated or unsaturated hydrocarbyl group having from about 4 to 20 carbon atoms.
The anionic dispersant may comprise polymeric dispersant containing sulfate or sulfonate. Such anionic dispersants include formaldehyde condensate of sodium naphthalene sulfonate, formaldehyde condensate of sodium alkylnaphthalene sulfonate, formaldehyde condensate of sodium phenol sulfonate, formaldehyde condensate of sodium phenol sulfate, and lignosulfonate, which preferably comprises sodium lignosulfonate. Preferably, the sodium lignosulfonate comprises sodium lignosulfonate having less than about 5.9 wt %, more preferably less than about 5 wt %, more preferably less than about 4.5 wt %, more preferably less than about 4 wt %, and most preferably less than about 3.6 wt % sulfonate sulfur based on the total weight of the sodium lignosulfonate.
The anionic dispersant may be present in an amount of from about 0.02 to about 20 wt %, more preferably from about 0.4 to about 7 wt %, and most preferably from about 0.9 to about 3 wt % of the weight of the cellulose-reactive size.
Preferred compositions comprise cationic dispersant, which is preferably cationically modified starch, cationically modified guar, or low charge cationic polymer. Preferably, the composition comprises cationically modified starch in an amount of from about 0.4 to about 400 wt %, more preferably from about 2 to about 100 wt %, and most preferably from about 10 to about 30 wt % of the weight of the cellulose-reactive size.
The salt may comprise a metal selected from Groups I, II, III, IV, V, and Transition Elements of the Periodic Table, and combinations thereof. Preferably, the salt comprises aluminum, magnesium calcium, or barium. Preferably, the composition comprises aluminum salt of the formula Al
x
(SO
4
)
y
(H
2
O)
z
, wherein x is 1 to 3, y is 1 to 4, and z is 0 to 20. Preferably, the aluminum salt is aluminum sulfate. The aluminum salt may also have the formula Al
n
(OH)
m
X
3n−m
, wherein X is a negative ion, n and m are integers greater than 0, and 3n−m is greater than 0. In such salts, the negative ion preferably comprises chloride or acetate, and the aluminum salt comprises polyaluminum chloride.
In on aspect of the invention, the salt may be present in an amount equivalent to from about 5.5 wt % aluminum to about 10 wt % aluminum, based on the weight of cellulose-reactive size; more preferably the salt is present in an amount equivalent to from about 6 wt % aluminum to about 8 wt % aluminum, based on the weight of cellulose-reactive size.
The present invention is further achieved by the provision of an aqueous composition comprising cellulose-reactive size, dispersant system comprising modified sodium lignosulfonate and at least one of cationic dispersant, non-ionic dispersant, and combinations thereof, and at least one salt comprising an el
Acquah Samuel A.
Greenblum & Bernstein P.L.C.
Hercules Incorporated
Rajouru U. K.
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