Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Reexamination Certificate
2000-07-26
2001-11-27
Aulakh, C. S. (Department: 1625)
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
C106S497000, C106S499000, C546S056000, C546S057000
Reexamination Certificate
active
06323342
ABSTRACT:
SUMMARY
The present invention relates to a quinacridone pigment, in particular to a novel form of a gamma-I type quinacridone pigment having a distinguished color characteristic, its preparation and its use as a pigment in high molecular weight organic materials.
BACKGROUND
Quinacridone, also referred to as 5,12-dihydroquino[2,3-b]acridine-7,14-dione, is a well-known pigment having the formula I
Quinacridone is known to exist in three major polymorphic modifications: the alpha, beta and gamma form.
The red alpha form is disclosed in U.S. Pat. No. 2,844,484; The beta form is disclosed as a magenta pigment in the U.S. Pat. Nos. 4,857,646; 5,229,515 and 5,281,269; and as a strong violet pigment in U.S. Pat. No. 2,844,485.
Several patents describe various forms of the red gamma quinacridone pigments. For example U.S. Pat. No. 2,844,581 describes a bluish red gamma-II, U.S. Pat. No. 3,074,950 describes a yellowish red gamma-I and U.S. Pat. No. 5,223,624 describes another yellowish red, a gamma-III- form, its X-ray-diffraction pattern and essential color characteristics.
U.S. Pat. No. 4,760,144 describes a process for the preparation of a yellowish red gamma-I type quinacridone form by conversion of the red gamma-II type quinacridone, in that the red gamma-II is milled in alcohol/base or premilled followed by an aftertreatment in a solvent.
The present invention relates to a novel gamma-I type quinacridone pigment having a distinguished color characteristic and its preparation by a new finishing or direct pigmentary procedure. In particular, the inventive pigment is characterized by its color space, its x-ray-diffraction pattern, which is a gamma-I type form; its specific surface area, which is typically in the range of 17±6 m
2
/g, and its primary pigment particle size, which is generally in the range of 0.1 to 0.5 &mgr;m.
In comparison to the known gamma quinacridone pigments the new gamma form shows a considerably higher chroma and a distinct difference in hue. The higher the chroma of an organic pigment the more valuable the pigment is. A higher chroma pigment is more attractive and offers better and more styling opportunities in combination with other pigments, for example with other organic, inorganic pigments or pearlescent mica pigments. Thus, a difference in chroma can be of considerable commercial importance. Due to the outstanding fastness properties, its excellent rheological properties and unique color characteristics, it is highly suited for use in plastics and coatings applications, particularly in automotive coating systems.
DETAILED DESCRIPTION
The present invention relates to a novel gamma-I type quinacridone pigment which is specified by its color space values. The color space values are obtained by known measurements (as noted hereafter) from for example sprayed paint panels of a pigment masstone. The color space values are defined using the 1976 CIE standard calculation as base and are expressed in L, A, B numbers.
The color space values of the new gamma-I type quinacridone according to the present invention are characterized by the following numbers:
COLOR SPACE
color space
Most Preferred
coordinates
Broad Range
Preferred Range
Range
C (Chroma)
48-59
49-58
50-57
L (Lightness)
40-47
40-46
41-45
A (red/green)
43-53
43-52
44-52
B (yellow/blue)
21-28
21-27
21-26
The color measurements were carried out in a large area view with a spectral component included using a ACS Colorimeter Program on an ACS, CS-5 Chromasensor from Applied Color Systems, Inc. and distributed by DATA COLOR International.
In order to measure the color data, the inventive pigment is first incorporated into a substrate, for example a basecoat/clearcoat paint system such as those described in Example 5. It is the color data of the pigmented substrate such as the coated panel or a pigmented plastic sheet which is then measured. The color data are measured at “complete hide”, which means that the substrate is pigmented to such an extent that any background color is not observable. At “complete hide” it is not possible to see the background color of a coated panel or the background color through a pigmented plastic sheet.
Appropriate substrates include lacquers, inks, coating compositions, and plastics. Especially appropriate coating compositions include the basecoat/clearcoat systems conventionally used in the automotive industry. Especially appropriate plastics include the polyvinyl halides, especially polyvinyl chloride, and the polyolefins, for example low or linear low density or high density polyethylene and polypropylene.
A pigment masstone means that the inventive pigment is the only pigment used to color the substrate.
In comparison to the known commercially available gamma quinacridones, such as MONASTRAL Red Y RT-759-D, from Ciba Specialty Chemicals, Tarrytown, N.Y. or HOSTAPERM Red E3B from Clariant, the new gamma quinacridone surprisingly has a yellower hue and a considerably higher chroma.
In general, at least 50 percent of the particles in the inventive pigment have a primary pigment particle size in the range of from 0.1 to 0.5 &mgr;m, preferably 0.1 to 0.3 &mgr;m as shown by an electron micrograph.
The inventive pigment shows a specific surface area of 17±6 m
2
/g, preferably 17±4 m
2
/g as determined by the BET method.
The inventive quinacridone pigment shows an X-ray diffraction pattern which shows the main peaks of a gamma quinacridone as depicted in FIG.
1
. The x-axis of
FIG. 1
reflects the double glancing angles while the y-axis reflects the intensity of the diffracted ray. Thus, the new gamma quinacridone is characterized by an x-ray diffraction pattern that exhibits three strong peaks corresponding to ±0.2 two &thgr; double glancing angles of 6.6, 13.9 and 26.5, two medium strength peaks corresponding to 13.2 and 13.5, and eight relatively weak peaks corresponding to 16.0, 17.0, 20.4, 21.8, 23.8, 25.1, 27.7 and 28.6. The X-ray diffraction pattern of the new high chroma gamma quinacridone is that of a gamma-I type. However, it can differ slightly with respect to the intensity and position of the 26.5 peak and the three peaks between 13 and 14.5 two &thgr; double glancing angles.
The new gamma quinacridone has superior pigment properties, such as high opacity, excellent rheological properties, heat stability and weatherability behavior, as well as a remarkably good flocculation resistance. It is easily dispersible and develops quickly a high color strength.
Although the inventive pigment shows excellent application properties, in order to further improve the pigment properties of the inventive gamma quinacridone pigment, texture-improving agents and/or anti-flocculants are optionally added before, during or after the corresponding preparatory process.
The texture-improving agent and/or anti-flocculant is preferably incorporated into the inventive gamma quinacridone pigment in an amount of from 0.05 to 20 percent, most preferably 1 to 10 percent, by weight, based on the combined weights of the gamma quinacridone pigment, texture-improving agent and/or anti-flocculant mixture.
Texture-improving agents are especially useful as an additional component which improves the properties of the inventive gamma quinacridone pigment. Suitable texture-improving agents include fatty acids having at least 12 carbon atoms, and amides, esters or salts of fatty acids. Typical fatty acid derived texture-improving agents include fatty acids such as stearic acid or behenic acid, and fatty amines such as laurylamine and stearylamine. In addition, fatty alcohols or ethoxylated fatty alcohols, polyols such as aliphatic 1,2-diols, glycerol mono stearate or polyvinylalcohol and epoxidized soy bean oil, waxes, resin acids and resin acid salts are suitable texture-improving agents.
Anti-flocculants are known in the pigments industry and are often also used as rheology improving agents, for example, pigment derivatives such as sulfonic acid, sulfonic acid salts like metal or quaternary alkylammonium salts or sulfonamide derivatives. Generally, antiflocculants which
Aulakh C. S.
Ciba Specialty Chemicals Corp.
Crichton David R.
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