Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2000-09-29
2003-01-07
Cain, Edward J. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S413000, C106S440000
Reexamination Certificate
active
06503970
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to yellow pigment compositions. In particular, the present invention relates to yellow pigment compositions containing co-processed organic pigments and inorganic pigments.
BACKGROUND OF THE INVENTION
Many conventional organic pigment blends, when subjected to a hot melt heat test (temperatures of 200° C. to 230° C. for a period of four hours), tend to decompose and discolor. Specifically, monoazo yellow pigments tend to undesirably bloom and discolor at high temperatures, so their use is disfavored. Disazo (diarylide) yellow pigments are much stronger tinctorially and show a much lower tendency to bloom and discolor at high temperatures. However, R. Az et al reports in Dyes and Pigments, 15, 1 (1991), that diarylide yellows are degraded to potentially carcinogenic by-products (e.g., 3,3′-dichlorobenzidine) in plastics processed above 200° C., a temperature lower than that used in processing most plastics (many plastics are processed at temperatures from 250° C. to 330° C.).
Most yellow pigments have one or two desirable properties in addition to several undesirable properties. For example, some yellow pigments are strong, but have poor weathering characteristics, poor heat resistance, undesirable tints and/or shades, and/or costly starting materials. Other yellow pigments have good weathering characteristics, but have poor heat resistance, are weak, have undesirable tints and/or shades, and/or costly starting materials.
Given these circumstances, when employing yellow pigments, one must accept a compromise on at least one desirable property. There is thus an unmet need in the art for yellow pigments having many desirable properties.
SUMMARY OF THE INVENTION
The present invention provides yellow pigment compositions containing co-processed organic pigments and inorganic pigments. The co-processed pigments have improved color properties as well as improved heat stability and weathering. In particular, the improved color properties of the co-processed pigments include desirable chroma, high color strength, and excellent lightfastness. The co-processed yellow pigments of the present invention are inexpensive to produce compared to other commercially available yellow pigment compositions. Moreover, in some embodiments, the co-processed yellow pigments of the present invention do not contain chlorine, and thus do not breakdown into potentially harmful chlorine containing components.
One aspect of the invention relates to yellow pigment composition containing at least one yellow nickel titanate and at least one yellow organic pigment containing a benzimidazolone moiety.
Another aspect of the invention relates to a yellow pigment composition containing from about 5% to about 80% by weight of at least one yellow nickel titanate and from about 20% to about 95% by weight of at least one yellow benzimidazolone pigment.
Yet another aspect of the invention relates to a method of making a yellow pigment composition involving the steps of combining at least one yellow nickel titanate and at least one yellow benzimidazolone pigment to form a mixture; and mixing the mixture to form a homogenous mixture of the yellow pigment composition.
DETAILED DESCRIPTION OF THE INVENTION
The present invention provides yellow pigment compositions containing at least co-processed yellow organic pigments and yellow inorganic pigments. The yellow pigment compositions may optionally contain additional pigments and/or additives. The yellow organic pigment and yellow inorganic pigment are co-processed in that an intimate mixture is formed. The yellow pigment compositions of the present invention contain at least a yellow nickel titanate as an inorganic pigment and a yellow benzimidazolone as an organic pigment.
While not wishing to be bound by any theory, it is believed that the formation of a stable composition with desirable properties is facilitated by surface to surface interactions between the oxide inorganic pigment and the benzimidazolone moiety of the organic pigment.
Yellow nickel titanate pigment is an inorganic pigment derived from a mixture of nickel oxide and titanium oxide and optionally antimony oxide. Nickel titanate has the general formula NiTiO
3
. In one embodiment, the yellow nickel titanate pigment is Pigment Yellow 53. Pigment Yellow 53 may be prepared by calcining a mixture of antimony oxide, nickel oxide and titanium oxide. Pigment Yellow 53 is commercially available from numerous sources, including Cerdec under the tradename of Irgacolor Yellow 10401. The yellow nickel titanate pigments are typically available in powder form.
Yellow nickel titanate pigments, including methods of their preparation, are found in the Pigment Handbook, Vol. 1, pp. 419-427 (1973), which is incorporated herein by reference. Generally, yellow nickel titanate pigments can be made by either precipitation or by calcination. The calcination process is characterized by a mixing of the raw materials required for the particular pigment (mixing. can be conducted by dry blending or by wet milling, for example). The mixture is then calcined at a high temperature, such as at about 980° C. After firing, the pigment is wet milled in a ball mill. The milled product is transferred to a filter press where it is washed and then dewatered to produce a filtercake. The filtercake is then dried and passed through a micropulverizer to produce a fine powder. The final step in the manufacturing process is to blend various batches to ensure that the finished product meets the quality control specifications for the pigment. Yellow nickel titanates can also be prepared by a precipitation process using a nickel salt with titanium dioxide, which is hydrated, and antimony oxide. The mixture is dried and calcined in the same manner as for the dry blended material.
In one embodiment, the yellow pigment compositions of the present invention contain from about 5% to about 80% by weight of at least one yellow nickel titanate inorganic pigment. In another embodiment, the yellow pigment compositions contain from about 10% to about 70% by weight of at least one yellow nickel titanate inorganic pigment. In yet another embodiment, the yellow pigment compositions contain from about 15% to about 60% by weight of at least one yellow nickel titanate inorganic pigment.
Yellow benzimidazolones are organic pigments containing a benzimidazolone moiety in its chemical structure. Benzimidazolones are azo organic pigments generally derived from an aromatic amine and a benzimidazolone coupler, wherein the aromatic amine is initially diazotized and then coupled to the benzimidazolone coupler. The coupling mixture may be heated, such as at temperatuires over 100° C. The yellow benzimidazolones may be monoazo organic pigments or disazo organic pigments.
In one embodiment, the yellow pigment compositions of the present invention contain from about 20% to about 95% by weight of at least one yellow benzimidazolone organic pigment. In another embodiment, the yellow pigment compositions contain from about 30% to about 90% by weight of at least one yellow benzimidazolone organic pigment. In yet another embodiment, the yellow pigment compositions contain from about 40% to about 85% by weight of at least one yellow benzimidazolone organic pigment.
Benzimidazolones organic pigment compositions and methods of preparing such are generally described in U.S. Pat. Nos. 4,080,321; 4,392,999; 4,555,568; 4,664,714; 5,352,281; and 5,756,757; which are hereby incorporated by reference in this regard.
Benzimidazolones organic pigment compositions are commercially available from a number of sources. The yellow benzimidazolone pigments are typically available in powder form. Examples of benzimidazolone organic pigments include Pigment Yellow 120, Pigment Yellow 151, Pigment Yellow 154, Pigment Yellow 156, and Pigment Yellow 175. The chemical formulae of some of these pigments are as follows:
The yellow pigment compositions may optionally contain additional organic and/or inorganic pigments and/or additives. In one embo
Engelhard Corporation
Keller Raymond F.
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