Holliday Pigments: Cool Blue Now in Bottles
Holliday Pigments ultramarines are ideal for clear polymers, where its transparency provides a superb crystal blue for bottles and packaging, a symbol of the purity within.
26 Dec 2009 --- One of the most ancient and revered of pigments, ultramarine blue has a distinctive and irreproducible colour. Already used extensively in food packaging, new grades have been developed to meet the tough demands of new plastics moulding techniques including, mineral water bottles, passing strict organoleptic tasting tests.
The Ancient Greeks regarded blue as the ultimate colour of perfect peace and purity, sacred to them as the blue of calm seas in mid-summer - halcyon days. They revered the kingfisher; the brilliant flash of blue from the European kingfisher’s wing reminds us of this, and the genus of kingfishers is also named Halcyon.
The rare mineral lapis lazuli was the original ingredient for this blue heritage, and created the colour revered by artists from the Egyptian pharaohs, through classical antiquity and the Renaissance to the present day. Until the 19th century, the only process to extract the pigment was expensive and complicated. In 1828, the first economically viable, synthetic version of ultramarine blue to reproduce lapis lazuli was discovered by Jean-Baptiste Guimet, and started the modern industrial process.
Development of principles
The principles used by Guimet are still the basis for Holliday Pigments’ manufacturing process today, 120 years after the firm’s start. The three main raw materials - clay, soda ash and sulphur – are mixed with a reducing agent and heated to 800°C in a kiln.
The material is then cooled and, when the temperature has fallen below 450°C, a small amount of oxygen is introduced to the kiln. This helps to provide the brightness and red hue of the commercially available ultramarine. The raw material is taken into a wet process of cleaning, grinding and classifying into intermediate powder, which is then blended to meet exact colour specifications.
Environmental purity
With consumers and legislators becoming ever more environmentally conscious, the purity and simplicity of ultramarine blue as a pigment is immediately attractive. This vibrant, red-shade of blue has a very unusual chromophone leading to a truly unique shade that cannot be recreated by other pigments.
With FDA approval for use in food contact and toy applications, and meeting food contact legislation worldwide, Holliday Pigments ultramarines are ideal for clear polymers, where its transparency provides a superb crystal blue for bottles and packaging, a symbol of the purity within.
New standards, new grades
Now two new grades of Ultramarine blue, Premier BC and Premier BC-R, have been introduced to satisfy new plastics processing performance requirements.
The improvements in polymers and processing equipment have made it possible to greatly increase throughput when injection moulding food containers. This means that the colorants used are being subjected to higher temperatures and shear forces than was previously the case. Holliday Pigments has been able to develop special grades which can withstand the most severe processing conditions without affecting the taste and odour of the contents.
Mineral water bottle caps
The two grades in the range are Premier BC developed for bottle caps for still mineral water or other non-acidic drinks and Premier BC-R, for bottle caps for carbonated mineral water or other acidic drinks. Bottle caps are widely recognised as particularly sensitive applications, and successful use here means that the ultramarines can be confidently used elsewhere for sensitive food packaging.
The superior performance of Premier BC and BC-R is ensured by improving the specification for volatiles content to a maximum of only 0.05% at 150ºC (standard grades are tested at 105°C) and the unreacted sulphur to a maximum of only 20ppm (standard grades 100ppm).
Development and evaluation
As part of the development, rigorous third party testing was performed to ensure that the new Ultramarine Premier BC/BC-R grades met the tougher plastic moulding conditions they would encounter at a blowing and bottling plant.
Initially, a masterbatch containing 30% Ultramarine blue and 1% zinc stearate in low-density polyethylene (Exxon LD251) was prepared using a twin screw extruder. Then, the test pieces were prepared on an industrial size injection moulder operated under typical production conditions of high temperature and shear. 2% of the masterbatch was mixed with high density polyethylene (BP Solvay 4020N 1331P) and the bottle cap test pieces were prepared using an Arburg 420C injection moulder fitted with a Husky hot runner meld.
Organoleptic assessment
Organoleptic assessments of the test pieces were made by Qualtech, an independent test facility specialising in the evaluation of organoleptic effects. Since any effect is most easily detected in plain mineral water, this was chosen as the test medium.
Glass bottles containing 1 litre of standard mineral water and 20 caps were sealed and placed in an oven set at 60ºC. After 48 hours the bottles were transferred to another oven at 20ºC for a further 48 hours. As a reference, a glass bottle containing the standard mineral water only was stored under the same conditions.
After the thermal treatment, samples from the water in each bottle were diluted at fixed ratios of one part sample to 1, 2, 4 and 6 parts standard mineral water respectively.
Each dilution was then tested by a panel of 8 expert tasters. In each case the taster was asked whether they could determine a difference between the reference and test samples, also to rate the ease with which they could determine this difference. An index was calculated based on the number of correct answers and the ease of determination ratings.
Results
The maximum possible index is 83. For this, all the tasters must correctly identify the test sample from the reference at every dilution, and rate the ease of detection at least 4 on a scale of 1 (almost impossible) to 5 (very easy).
The actual result was an index of 38 for Premier BC and 32 for Premier BC-R, both results classed as not significant across the full range of dilutions. As well as reproducing the more difficult processing conditions, the storage conditions of the water which attempt to induce tainting far exceed what would normally be experienced by bottles of water.
From this evaluation it can be concluded that neither Ultramarine Premier BC nor Premier BC-R have any effect on the taste of mineral water. By inference, the new pigment grades are also suitable for other critical food packaging applications.
Holliday Pigments have also effectively demonstrated that its ability to match technological developments in plastics with development in pigment processing, maintaining a long tradition of working with industry to create outstanding product.
The Ancient Greeks regarded blue as the ultimate colour of perfect peace and purity, sacred to them as the blue of calm seas in mid-summer - halcyon days. They revered the kingfisher; the brilliant flash of blue from the European kingfisher’s wing reminds us of this, and the genus of kingfishers is also named Halcyon.
The rare mineral lapis lazuli was the original ingredient for this blue heritage, and created the colour revered by artists from the Egyptian pharaohs, through classical antiquity and the Renaissance to the present day. Until the 19th century, the only process to extract the pigment was expensive and complicated. In 1828, the first economically viable, synthetic version of ultramarine blue to reproduce lapis lazuli was discovered by Jean-Baptiste Guimet, and started the modern industrial process.
Development of principles
The principles used by Guimet are still the basis for Holliday Pigments’ manufacturing process today, 120 years after the firm’s start. The three main raw materials - clay, soda ash and sulphur – are mixed with a reducing agent and heated to 800°C in a kiln.
The material is then cooled and, when the temperature has fallen below 450°C, a small amount of oxygen is introduced to the kiln. This helps to provide the brightness and red hue of the commercially available ultramarine. The raw material is taken into a wet process of cleaning, grinding and classifying into intermediate powder, which is then blended to meet exact colour specifications.
Environmental purity
With consumers and legislators becoming ever more environmentally conscious, the purity and simplicity of ultramarine blue as a pigment is immediately attractive. This vibrant, red-shade of blue has a very unusual chromophone leading to a truly unique shade that cannot be recreated by other pigments.
With FDA approval for use in food contact and toy applications, and meeting food contact legislation worldwide, Holliday Pigments ultramarines are ideal for clear polymers, where its transparency provides a superb crystal blue for bottles and packaging, a symbol of the purity within.
New standards, new grades
Now two new grades of Ultramarine blue, Premier BC and Premier BC-R, have been introduced to satisfy new plastics processing performance requirements.
The improvements in polymers and processing equipment have made it possible to greatly increase throughput when injection moulding food containers. This means that the colorants used are being subjected to higher temperatures and shear forces than was previously the case. Holliday Pigments has been able to develop special grades which can withstand the most severe processing conditions without affecting the taste and odour of the contents.
Mineral water bottle caps
The two grades in the range are Premier BC developed for bottle caps for still mineral water or other non-acidic drinks and Premier BC-R, for bottle caps for carbonated mineral water or other acidic drinks. Bottle caps are widely recognised as particularly sensitive applications, and successful use here means that the ultramarines can be confidently used elsewhere for sensitive food packaging.
The superior performance of Premier BC and BC-R is ensured by improving the specification for volatiles content to a maximum of only 0.05% at 150ºC (standard grades are tested at 105°C) and the unreacted sulphur to a maximum of only 20ppm (standard grades 100ppm).
Development and evaluation
As part of the development, rigorous third party testing was performed to ensure that the new Ultramarine Premier BC/BC-R grades met the tougher plastic moulding conditions they would encounter at a blowing and bottling plant.
Initially, a masterbatch containing 30% Ultramarine blue and 1% zinc stearate in low-density polyethylene (Exxon LD251) was prepared using a twin screw extruder. Then, the test pieces were prepared on an industrial size injection moulder operated under typical production conditions of high temperature and shear. 2% of the masterbatch was mixed with high density polyethylene (BP Solvay 4020N 1331P) and the bottle cap test pieces were prepared using an Arburg 420C injection moulder fitted with a Husky hot runner meld.
Organoleptic assessment
Organoleptic assessments of the test pieces were made by Qualtech, an independent test facility specialising in the evaluation of organoleptic effects. Since any effect is most easily detected in plain mineral water, this was chosen as the test medium.
Glass bottles containing 1 litre of standard mineral water and 20 caps were sealed and placed in an oven set at 60ºC. After 48 hours the bottles were transferred to another oven at 20ºC for a further 48 hours. As a reference, a glass bottle containing the standard mineral water only was stored under the same conditions.
After the thermal treatment, samples from the water in each bottle were diluted at fixed ratios of one part sample to 1, 2, 4 and 6 parts standard mineral water respectively.
Each dilution was then tested by a panel of 8 expert tasters. In each case the taster was asked whether they could determine a difference between the reference and test samples, also to rate the ease with which they could determine this difference. An index was calculated based on the number of correct answers and the ease of determination ratings.
Results
The maximum possible index is 83. For this, all the tasters must correctly identify the test sample from the reference at every dilution, and rate the ease of detection at least 4 on a scale of 1 (almost impossible) to 5 (very easy).
The actual result was an index of 38 for Premier BC and 32 for Premier BC-R, both results classed as not significant across the full range of dilutions. As well as reproducing the more difficult processing conditions, the storage conditions of the water which attempt to induce tainting far exceed what would normally be experienced by bottles of water.
From this evaluation it can be concluded that neither Ultramarine Premier BC nor Premier BC-R have any effect on the taste of mineral water. By inference, the new pigment grades are also suitable for other critical food packaging applications.
Holliday Pigments have also effectively demonstrated that its ability to match technological developments in plastics with development in pigment processing, maintaining a long tradition of working with industry to create outstanding product.
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