Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2002-07-31
2003-11-11
Sanders, Kriellion A. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S430000, C524S447000, C524S449000, C524S451000, C524S492000, C523S200000, C252S400620, C252S401000, C252S402000, C252S403000, C106S417000, C106S493000, C106S500000
Reexamination Certificate
active
06646037
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to pigments, and in particular, pigments that have been treated with certain organosulfonic compounds, such as organosulfonic acids and their salts.
BACKGROUND OF THE INVENTION
The incorporation of pigments into polymer matrices has been performed for many years, and over the years, pigments have been and continue to be incorporated into polymer matrices for many reasons. For example, pigments may be used as fillers. They may also be used to impart better physical and chemical attributes to polymer matrices, including decreased chemical activity and improved thermal stability, especially lacing resistance in extruded polymer film applications. In order to obtain different benefits, pigments may be treated in different ways, including by adding surface treatments.
Commonly used pigments for incorporation into polymer matrices include titanium dioxide and kaolin. Commonly known surface treatments that have been applied to these pigments include silanes, alkanolamines, polyols, alkylphosphonic acids and phosphorylated polyenes. The optimal treatment will in part depend on the attributes that one wants in a treated pigment, which will in part depend on the application in which it will be used. Often one wants to provide a hydrophobic pigment that is stable, easy to prepare, cost effective, able to be dispersed to a high degree in polymers, and not reactive in the presence of other additives such as lithopone. However, despite the numerous known surface treatments, for various reasons, including cost and desired properties, no known surface treatments are ideal for all applications. Thus, there is always a need to develop new and better treatments for pigments.
One under-explored option for treating pigments is the use of organosulfonic compounds such as organosulfonic acids and their salts. These compounds have been suggested as treatments for calcium carbonate in order to improve flow properties of molding compositions and the mechanical properties of shaped articles made from molding compositions. However, such limited use has not been extended to other applications, such as metal oxides and their masterbatches in polymers such as polyethylene, or articles made therefrom.
Organosulfonic compounds have also been suggested as surfactants that may be used with pigments by bonding to the pigments through metal cations. For example, U.S. Pat. No. 5,260,353 teaches using hydrolyzed metal cations to bond surfactant species chemically to particulate surfaces with a requirement of the addition of a surfactant treatment in a slurry within a specified pH range that is dependant on the metal cation. By operating at a particular acidic pH, this prior art method uses metal ions to activate particulate surfaces and to permit chemical bonding of a surfactant to the surface at the activated metal site. Under this method, it is suggested that a surfactant is firmly bonded to the substrate surface. Because of the specific conditions under which this process must be practiced, it may be undesirably cumbersome to control if one wants to ensure minimal loss of the surface treatment.
Surprisingly, it was found that a hydrophilic pigment that comprises a pigmentary base with an organosulfonic compound that is not tightly bound, but that has good dispersiblity could be produced. The present invention provides economical and easily prepared novel pigments that have excellent dispersion in polymer concentrates comprising up to 85% of the treated TiO
2
based upon the weight of the polymer matrix and provide excellent resistance to lacing when processed into thin films such as polyethylene films at high temperatures. The present invention also provides methods for making these pigments. Pigments produced according to the present invention may be incorporated into a polymer matrix that may be an end-product in and of itself or a product that will be further processed such as in a masterbatch that can be let down into a polymeric film.
SUMMARY OF THE INVENTION
The present invention provides treated pigments for use in polymer matrices, as well as methods for making these pigments. The treated pigments may comprise a pigmentary base that is treated with one or more organosulfonic compounds. Optionally, these pigments will further comprise a metal oxide. The treated pigments may be formed by treating a pigmentary base with an organosulfonic acid or a salt of an organosulfonic acid that may be represented by the following formula:
(R—SO
3
)
x
M
x+
wherein x=1, 2, 3, or 4
M is a hydrogen, ammonium, organoammonium or metal ion with a valence of +1, +2, +3 or +4; and R is an organic group having from 2 to 22 carbon atoms.
According to one embodiment, the present invention provides a pigment comprising:
a. a pigmentary base; and
b. an organosulfonic compound having the formula:
(R—SO
3
)
x
M
x+
wherein x=1, 2, 3 or 4
M is a hydrogen, ammonium, organoammonium or metal ion with a valence of +1, +2, +3 or +4 and R is an organic group having from 2 to 22 carbon atoms.
The treated pigments of the present invention may be combined with and readily dispersed into polymers to form polymer matrices after the pigmentary base has been combined with the organosulfonic compound. The pigments of the present invention, which have been treated with organosulfonic compounds, exhibit excellent lacing resistance when incorporated into polymeric articles such as films. Additionally, the present invention also provides a pigment that does not generate noxious odors when mixed with lithopone at high temperatures.
According to one preferred method for making the pigments of the present invention, a pigmentary base is combined with an organosulfonic compound of Formula I in an environment that has a pH of greater than or equal to about pH 6 prior to addition of the organosulfonic compound. It is also preferable that the pH after the addition of the organosulfonic compound is greater than or equal to about pH6. Further, these substances are preferably combined downstream of any filtering action.
The treated pigments of the present invention may also be used to prepare highly loaded polymer masterbatches. The treated pigments exhibit excellent dispersion qualities when incorporated into masterbatches containing up to about 85% of the pigments treated with organosulfonic compounds. These highly loaded masterbatches are especially useful in applications in which dispersion and thermal stability, especially resistance to lacing, are critical.
The treated pigments of the present invention have the advantages of being stable, easy to prepare, able to be dispersed to a high degree in polymers and unreactive in the presence of other additives such as lithopone. Such treated pigments may be useful in the manufacture of plastics and other products.
DETAILED DESCRIPTION OF THE INVENTION
The present invention provides pigments for use in connection with polymers and the methods for making these pigments. According to the present invention, a pigmentary base is treated with an organosulfonic compound. The resulting treated pigment may then be combined with a polymer to form a polymer matrix.
The present disclosure is not intended to be a treatise on either pigments or the production of polymer matrices and readers are referred to appropriate, available texts and other materials in the field for additional and detailed information on any aspect of practicing this invention.
The treated pigments made according to present invention comprise a pigmentary base that is treated with an organosulfonic compound. Preferably, the pigment further comprises a metal oxide such as aluminum oxide. Suitable pigmentary bases for use in the present invention include titanium dioxide, kaolin, talc and mica. The phrase “pigmentary base” as used herein refers to the pigment that has not been treated with an organosulfonic compound. Preferably, titanium dioxide is the chosen pigmentary base. When the pigmentary base is titanium dioxide, the titanium dioxide m
El-Shoubary Modasser
Kostelnik Robert
Wheddon Charles
Kalow & Springut LLP
Locke, Esq. Scott D.
Millennium Inorganic Chemicals, Inc.
Sanders Kriellion A.
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