Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2001-11-26
2004-03-30
Yoon, Tae H. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S431000, C523S205000, C106S436000, C427S218000, C427S220000, C427S384000, C428S357000, C428S363000
Reexamination Certificate
active
06713543
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to novel pigments, and in particular, pigments that have been treated with certain organo-phosphoric acid compounds and/or their salts.
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 improved thermal stability, especially lacing resistance in extruded polymer film applications, and decreased chemical activity. In order to obtain different benefits, pigments may be treated in different ways, including by adding surface treatments.
Commonly used pigments include titanium dioxide, kaolin and calcium carbonate. Commonly known surface treatments that have been applied to pigments include silanes, alkylphosphonic acids and phosphorylated polyenes.
The precise attributes that one wants in a treated pigment will depend in part 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, can be dispersed to a high degree in polymers, and does not react 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 organo-phosphoric acids, including the esters of phosphoric acids and their corresponding salts. These compounds have been suggested as useful when mixed in relatively large amounts with pigments and to form suspensions in, for example, aqueous coatings applications. However, such a use produces a unique product that may be used only in a limited application. Thus, the teachings for the use of relatively large amounts of esters of phosphoric acids in aqueous coatings applications do not suggest the treatment of pigments with low levels of the organo-phosphoric acids of this invention or that the pigments treated with the low levels of the organo-phosphoric acids of this invention would have utility in plastics.
The present invention provides economical and easily prepared novel pigments that possess resistance to lacing when incorporated into polymeric articles (such as films), do not produce objectionable side reactions when mixed with common plastics additives such as lithopone, which contains zinc sulfide, and are stable such that they possess low levels of extractable organics. Further, durable plastics products that incorporate the treated pigments of the present invention are likely to resist yellowing when phenolic-type antioxidants are used.
SUMMARY OF THE INVENTION
The present invention provides novel treated pigments for use in polymer matrices. According to the present invention, pigmentary bases are treated with one or more organo-phosphoric acid compounds and/or their salts in order to form treated pigments.
In one embodiment, the treated pigment comprises a pigmentary base that may be treated with the reaction products of: (1) at least one organic alcohol; and (2) P
2
O
5
and/or phosphoric acid. The phrases “at least one organic alcohol” and “organic alcohols” mean one or more types of organic alcohols, for example, a solution of hexanol or octanol or a mixture of hexanol and octanol. The organic alcohols, P
2
O
5
and phosphoric acid are selected such that their reaction products include an organo-acid phosphate that may be represented by the formula:
(R—O)
x
PO(OH)
y
Formula 1
wherein
x=1 or 2;
y=3−x; and
R is an organic group having from 2 to 22 carbon atoms.
Alternatively, one may start with the organo-acid phosphate or its corresponding salt directly if it is available, rather than produce it from the reactants described above.
In another embodiment, the present invention provides for a pigment treated with an organopyrophosphate or an organopolyphosphate and/or their corresponding salts. The organopyrophosphate and organopolyphosphate compounds may be represented by the formula:
R′
n
−P
(n−2)
O
4+[3(n−3)]
Formula 2
wherein
n=4-14; and
each R′ is an organic group having from 2 to 22 carbon atoms or hydrogen and within any one molecule, any two or more R′ groups may be the same provided that at least one of the R′ groups is not hydrogen.
In still another embodiment, the present invention provides for a treated pigment comprised of a pigmentary base that has been treated with an organometaphosphate compound and/or its corresponding salt wherein the organometaphosphate compound may be represented by the formula:
(R″PO
3
)
m
Formula 3
wherein
m=1-14, and each R″ is an organic group having from 2 to 22 carbon atoms or hydrogen and within any one molecule, any two or more R″ groups may be the same provided that at least one of the R″ groups is not hydrogen. Collectively, the group of compounds represented by Formulas 1-3, i.e., the organo-acid phosphate, the organopolyphosphate, the organopyrophosphate and the organometaphosphate are referred to herein as “organo-phosphoric acids.”
The treated pigments of the present invention may be combined with and readily dispersed into polymers to form polymer matrices. For example, the pigments of the present invention may be incorporated into a polymer matrix containing up to about 85% of organo-phosphoric acid treated titanium dioxide pigment, based on the weight of the polymer matrix to be produced. The polymer matrix may be an end-product in and of itself or a product that will be further processed such as in a masterbatch, which can be let down into a polymeric film. These polymer matrices have improved physical properties such as impact strength, tensile strength and flexural characteristics.
The treated pigments of the present invention may also be used to prepare highly loaded polymer masterbatches. 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 pigments that are stable, easy to prepare, cost effective, can be dispersed to a high degree in polymers, and do not react 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 novel pigments for use in connection with polymers and offers several benefits over currently used pigments. According to the present invention, pigmentary bases are treated with an organo-phosphoric acid that may be an organo-acid phosphate, an organopyrophosphate, an organopolyphosphate or an organometaphosphate, or a salt of any of the aforementioned compounds. The pigmentary bases may also be treated with mixtures of any of the aforementioned compounds and/or their salts. The resulting treated pigments may then be combined with polymers to form novel polymer matrices.
The present disclosure is not intended to be a treatise on either pigments or the production of polymer matrices. 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.
Suitable pigmentary bases for use in the present invention include titanium dioxide, kaolin, talc, mica and calcium carbonate. The phrase “pigmentary base” as used herein refers to the pigment that has not been treated with an organo-phosphoric acid compound. Preferably, titanium dioxide is the chosen pigmentary base. When the pigmentary base is titanium dioxide, the titanium dioxide may be either rutile or anatase, both of which m
El-Shoubary Modasser
Kostelnik Robert J.
Kalow & Springut LLP
Locke, Esq. Scott D.
Millennium Inorganic Chemicals, Inc.
Yoon Tae H.
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