Folding carton and corrugated converters will find equipment displays and educational opportunities in die-cutting, foil stamping, embossing, and more.Read more
How well do you understand the relationship between your films and your corona treater?Read more
EVOH allows conversion from foil and metallized film laminations to co-extruded barrier films.Read more
Mark Miller helps you identify the right material selection for tooling that will carry fluid to your substrate.Read more
News | New Products
ECG seminar will feature a wide range of topics and break-out sessions
The Novamelt location in Germany, where hot melt p-s adhesives are produced, is expected to play a key role in the integration of the two companies
According to a study from the Corrugated Packaging Alliance, shipping in corrugated containers saves 10.4 percent annually compared to RPCs
The 2015 North American Paperboard Packaging Competition, which recognizes excellence through the entire converting process, is accepting entries
A recent show in China was the occasion for the introduction of the modular ‘Concept’ and a carbon fibre chamber doctor blade
Visit Booth 205 at Kansas City Convention Center April 27-29
The new event, which will focus on processing and packaging technologies serving the food and beverage areas, will launch in 2017
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Visit Kelly on Static from Static control expert Dr. Kelly Robinson, president of Electrostatic Answers; Kelly has 27+ years of experience in problem-solving and consulting.
Visit Tim's Web Lines to handle and wind your paper, film, foil, and similar products. Take advantage of Tim’s 25+ years just like over 100 converters have.
Visit Mark's Coating Matters from fluid coating expert Mark D. Miller; Process improvement and project management for precision roll-to-roll coating applications.
Visit Marketing Mojo for dynamic marketing insights from Stephanie Millman that inspire new ideas on how to stay on top of your customer’s mind.
Visit Yo’s Yarns to share the thoughts, impressions, experiences, and news that impact the converting industry. . . or anything else that happens to be on her mind!
Visit Tom's Poly Ploys, where Tom will be writing on various topics that the typical polymer processor would encounter on the job.
- July 01, 2003, Dr. Richard M. Podhajny, Ph.D., Contributing Editor
Recently, a question came in from one of our readers (thank you, Joe Woods) as to how one can assure the copper phthalocyanine green pigment purchased from two suppliers is the same chemically.
Pigment Green 7 has a CAS Registry Number of 1328-53-6. It is commonly referred to as Phthalo Green and has a bright bluish green color.
Copper phthalocyanine green pigment is a unique product that is essentially copper phthalocyanine blue pigment in which most of the hydrogen atoms have been replaced with chlorine atoms. The commercial chemical composition of copper phthalocyanine green can vary due to the number of chlorine atoms. They range between 14 chlorine atoms to a maximum of 16. As a result, it is possible to obtain the same pigment from two different suppliers with the same CAS number but with differences in chemical composition.
Copper phthalocyanine green is produced commercially by the direct chlorination of copper phthalocyanine blue pigment as a melt of sodium chloride and aluminum chloride. Chlorine is introduced at an elevated temperature and the melt cooled. Grinding the pigments in the presence of soluble salts, which can be washed out in the purification process, can produce particles of uniform size and maximize color strength.
Chlorine atoms are electronegative and have a strong effect on the electron distribution within the phthalocyanine molecular structure. Their presence shifts the color from blue associated with copper phthalocyanine blue to a bright green in this chlorinated copper phthalocyanine blue structure.
In combination with copper phthalocyanine green 36 (copper phthalocyanine pigment that contains chlorine and bromine atoms), a broad tonal range of phthalocyanine to the green-yellow end of the visible spectrum is allowed.
This chemical structure is extremely stable and chemically resistant. This pigment is highly resistant to acids, alkali, solvents, heat, and UV.
Due to these outstanding properties, copper phthalocyanine green is used in inks, coatings, and most plastics because of its high transparency. These pigments inherently are insoluble and show no apparent migration in food packaging.
If you are planning to source this material from outside the US, special attention should be made to assure there are no trace PCBs that may be present due to production and purification differences.
It is not easy to differentiate copper phthalocyanine greens from each other unless you have access to good analytical tools. Obviously, if you can measure the chlorine between samples, you can distinguish how close they are to each other.
The level of chlorine (Cl) can range from 46.9% (for Cl14) or 48.7% (for Cl15). Higher levels of chlorine are possible (Cl16), but due to difficulty in the synthesis and chemical stability, they usually are not available commercially.
It also may be possible to distinguish different copper phthalocyanine greens through thin-layer chromatography. Again, this requires analytical experts to differentiate the thin-layer chromatography pattern with appropriate solvent. Due to the low solubility of these products, this is a challenge.
Perhaps another approach would be to use FTIR infrared spectroscopy. However, while this analytical approach may be suitable, it requires considerable analytical expertise.
If a laboratory has access to NMR and a suitable deuterated solvent, then NMR would clearly pick out the protons in the case of Cl14 or Cl15 copper phthalocyanine green and differentiate their structures.
As you can see, the answer to our reader's question gets complicated. I suspect the best way to handle this is to obtain a Certificate of Analysis from the pigment supplier with the percent of chlorine level present.
Copper phthalocyanine green is an outstanding pigment that cannot easily be replaced. It is the green pigment standard, which is used in the printing ink and packaging industry.
Dr. Richard M. Podhajny has been in the packaging and printing industry for more than 30 years Contact him at 267/695-7717; email@example.com.