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Developments in Plastics Colorants

Developments in Plastics Colorants

15-Jul-09
Techno - commercial information on plastics Industry - News on Plastics Industry - Plastemart.com
 
Developments in Plastics Colorants

Developments in Plastics Colorants

 

Colorants and special effects are the largest group of a broad range of additives and masterbatches available to alter appearance, functionality, performance, safety, cost effectiveness, and processing efficiency of resins. There are two basic types of colourants as per S pecialChem . They are:
* Dyes, which are soluble and become a part of the plastics they are mixed with.
* Pigments, which are insoluble and must be dispersed in the polymer matrix.

This is illustrated by the exhibit given below:.

 
 

Color Basics [Source: Shepherd Color Company]

 

Bright, clear, products can more readily be achieved with dyes, while pigments, which are solids, are better used for deep, saturated, opaque or translucent. Organic colorants, both dyes and pigments, are increasingly used, displacing inorganic materials, particularly those relying on heavy metals such as cadmium or lead chromates.
Besides basic colorants, special effect systems, green technology, and new additive systems provide the plastics industry with continuously expanding options for color and aesthetic solutions. Some of today's most exciting developments are the result of collaboration between colour scientists and processors to accomplish appearance effects in fabricated products not possible by the use of colorants alone. Innovative combinations of colors, additives, and polymers can create new effects that convey a full range of innovative visuals including texture, reflectivity, luster, gloss, frost, and softness. As per SpecialChem, these include:

Color Developments for Bioplastics
Additives, including colorants, for bioplastics are being widely investigated. Of particular interest are colorants that have no adverse effect on health or the environment and do not compromise bioplastics' compliance with compostability standards. In addition to traditional pigments that can be used in biopolymers, bio-derived colorants based on plants and other renewable materials are now available from multiple companies.
Renol-natur color masterbatches from Clariant designed for application in PLA, polyhydroxyalkanoate (PHA), and starch based biopolymers are made from 100% sustainable natural sources. These bio-derived colors are very earthy and organic looking. While some boast excellent clarity, light fastness may be still the constraint. Current bio-derived colorants include:
* Orange curcuma (root of turmeric spice plant)
* Yellow urucum (tropical flower)
* Green (chlorophyll & other plant sources)
* Carmine red (cochineal insect)
* Blue (under development)
Additional shades and tones are possible by combining the colors. The Renol-natur materials are biodegradable and compostable. All Renol-natur colors meet or exceed the EN 13432 standard for biodegradable plastics packaging. OnColor BIO Colorants from PolyOne are a range of color concentrate products offering a full pallet of color choices, both transparent and opaque developed specifically for use with biodegradable resins including PLA, PHA, PHBV, PBS, PBAT (polybutylene adipate-co-terephthalate) and blends of these different polymer families. They can be used at normal loadings and dosed in the standard way. Based on sustainable raw materials, OnColor BIO color concentrates meet several global industry and composting standards including EN 13432, ASTM D6400 (USA), BPS GREENPLA (Japan) and DIN CERTCO (Germany). Teknor Color for Biopolymers is centered on three series of color concentrates for use in PLA and blends. The three series of colorants differ in terms of their carrier materials, which are either PLA or polyesters compatible with PLA and thus readily blended into it. The PLA-carrier concentrates are for use in PLA-compatible polymers. Biodegradable co-polyester carrier concentrates have a petrochemical carrier material and are recommended for blown film and other applications requiring greater flexibility than is provided by 100% PLA formulations. PETek PET-carrier concentrates are for non-biodegradable applications where use of a biopolymer base resin such as PLA is desired.

Special Effects in the Consumer Market
Special effects colorants are growing in importance as a marketing tool particularly for consumer products in which colors and color effects are employed to create and express an image or brand. Employment of additives to augment the appearance of plastic products via special effect colorants that create features such as sparkle, luster and color shifting has been found to be an extraordinarily effective way to differentiate products. Market research has determined that products and their packaging utilizing special effect colorants are more likely to catch the attention of the consumer and are perceived to be more striking, more unique, more colorful, and modern than competing products or packaging. Consequently, the technology of producing visual effects in plastics has advanced considerably. Additives suppliers are continually expanding their palette to introduce pearlescent, thermochromic or metallic shine, sparkle and luster as just some of the many effects increasingly developed by their color designers who follow the newest color trends in the consumer industries.
* Enhanced Pearlescence
A unique range of Xymara effect pigments for plastics applications is being developed by Ciba Specialty Chemicals that provide pearlescent and metallic special effects. These pigments make use of transparent mica platelets coated with very thin layers of metal oxides (i.e. TiO2 and/or Fe2O3) to create in plastic the pearlescent luster/color of natural pearls or the glitter of metal. Various effects are produced by altering particle size with small particles providing a soft silky sheen, and larger particles conveying more intense glitter. The metal oxide coating selected and its thickness can generate a wide range of color effects which alone or together with other unique transparent and opaque pigments can form brilliant combinations of transparent colours and shimmering effects available to the plastics product designer. The combination of transparency, refractive index, and multiple-refraction accounts for the various effects achieved. The most recently introduced range of pearlescent effects pigments, Xymara XPS, has anti-yellowing properties that enhances product appearance and extends its life. Mica-based pearlescent pigments tend to cause yellowing of plastic when exposed to light. Xymara XPS makes use of a surface treatment to stabilize the pearlescent pigments and inhibit this yellowing tendency.
* Metal Look-Alikes
LiquidMetal Colors, by Ampacet, a new line of colorant special-effect masterbatches that allows blow molded and extruded PET (polyethylene terephthalate) packaging to have the look of highly reflective metal provides designers with new options. They also provide improved sustainability and safety in use while lowering cost by eliminating the need, processing steps, and expense incurred by primary metals and environmentally-unfriendly chemicals required for metal finishing and decorating. A recent addition, 'Bright Chrome' offers an environmentally friendly, lighter weight, lower cost, chrome alternative providing the power, allure and sheen of chrome without the corrosive chemical baths, multi-stage processing, and the high fabricating cost. The dry colorant masterbatch, which is conveniently added into the resin stream prior to molding, becomes part of the polymer matrix. 'Brushed Brilliance' masterbatch, the latest in this LiquidMetal family of products captures the dimensional texture, visual effects and optical character of aluminum. The trendy, upscale, alternative to brushed aluminum captures nuances of metal at a fraction of the cost. This plastics alternative to aluminum is lighter in weight and overcomes metal-forming design restrictions, reduces costs and greatly simplifies production.
* Pyrisma Interference Pigments for Coating Applications
The innovative Pyrisma products from Merck, a systematic group of pearl effect pigments based on an optimized mica fraction, were developed particularly for the needs of the coating industry. In high performance plastics coating systems, these pigments deliver excellent appearance. The pigments with their outstanding color saturation and specially developed particle size distribution set a new standard, providing excellent performance and stability against environmental influences. The color angles of each Pyrisma interference pigment were designed with the aid of sophisticated, and highly complex colorimetric calculations according to the 'Merck Color Space Concept' to offer unique hues with high color saturation. The carefully designed Pyrisma surface treatment provides an innovative solution to fulfill the complex needs of modern plastic part coating systems and applications, supplying excellent performance and durability under a range of environmental conditions. The pigments find application in many indoor and outdoor plastic coatings applications.

Infrared Reflective Pigments
* Cool Pigments

Pigments provide color by absorbing/reflecting different parts of the sun's wavelength spectrum based on their chemistry with the light reflected appearing as color to the human eye. Pigments also have infrared (IR) characteristics. While nearly 40% of the sun's energy occurs in the visible range of the light spectrum (400-650 nm), more than 50% is in the non-visible IR region (650-2500nm), the range largely responsible for heat build-up. Though organic pigments can offer very vivid and bright colors they are typically not as lightfast or opaque as the inorganic pigments that are used where color change due to environmental exposure might occur. For the most demanding applications, a special group of inorganic pigments known as Complex Inorganic Color Pigments (CICP) are employed. Certain pigments within this group exhibit high IR-reflectivity for a given visible color. They have been designed to reflect IR light while still absorbing the same amount of visible light. These pigments with low IR absorption are deemed to be cool while conversely pigments with high IR absorption are hot.
Pigments provide color by absorbing/reflecting different parts of the sun's wavelength spectrum based on their chemistry with the light reflected appearing as color to the human eye. Pigments also have infrared (IR) characteristics. While nearly 40% of the sun's energy occurs in the visible range of the light spectrum (400-700 nm), more than 50% is in the non-visible IR region (700-2500nm), the range largely responsible for heat build-up. Though organic pigments can offer very vivid and bright colors they are typically not as lightfast or opaque as the inorganic pigments that are used where color change due to environmental exposure might occur. For the most demanding applications, a special group of inorganic pigments known as Complex Inorganic Color Pigments (CICP) are employed. Certain pigments within this group exhibit high IR-reflectivity for a given visible color. They have been designed to reflect IR light while still absorbing the same amount of visible light. These pigments with low IR absorption are deemed to be cool while conversely pigments with high IR absorption are hot.
* New Arctic Black
A new black pigment introduced recently by Shepherd Color Company designed specifically for coloring fibers and films can be used to minimize heat build-up and reduce overall energy costs. This pigment reflects the IR portion of the sun's light thereby reducing the temperature of products exposed to the sun without sacrificing the black color. This can retard degradation while extending product life and cooling interior spaces. The IR reflective pigment, Black 40P925 is a new color in the 'Precise' product line of extremely durable pigments and is also part of the 'Arctic' range of pigments. 'Precise Arctic' IR reflective pigments designed to mitigate solar-induced heat build-up find application in outdoor furniture textiles, carpets, awnings, doors, siding, and other outdoor products.

Regulatory Compliant Colorants
Medical/Pharmaceutical Advanced Colorants
* Fashion-Advanced Medical Colors: A new LEDA compounded color technology can help designers break the beige and white barriers imposed on medical applications. The 'Rx Medical' line of LEDA colors and special effects developed by Bayer Material Science for use with PC and PC/ABS brings medical industry-compliant color possibilities to this market. The medical industry has been calling for a fresh color look in medical applications, but designers have been constrained by the lack of ISO-compliant colorant options. FDA-modified ISO 10993-1 is the accepted standard for biocompatibility of materials used to produce medical devices. Polycarbonate resins containing the four new Rx Medical LEDA colors (First Aid, Stat, X-Ray, and Electro) are ISO 10993-1 compliant, providing innovative color options for the design of medical devices, such as those used in drug delivery and surgical instrument components. The latest Color Marketing Group palettes indicate that subdued hues will be increasingly dominant in 2009 and beyond.
* First Amber Masterbatches for Prescription Bottles:
Two amber masterbatches for PET used in pharmaceutical prescription bottles have been developed by Ampacet that let molders color PET in their facilities rather than rely on pre-colored resin. While molders have wanted such a color masterbatch for sometime in order to gain greater process flexibility and operating efficiency in injection blow molding pharmaceutical bottles, the rigorous specifications set for these bottles have been a major obstacle. The new resin masterbatches Ampacet 681725-PT and 681726-PT meet the strict light fastness, UV protection, clarity, color, extractability and other requirements set for pharmaceutical bottles including USP Section 661. Both comply with this difficult volatiles extraction standard in which a solvent extracts volatiles at 49° C for 10 days. Furthermore prescription bottle light transmission in cannot be greater than 10% between 290 and 450 nm. The transmission of 681725-PT is 3.6% and that of 681726-PT is 0.7%. Moreover 681726-PT contains a UV additive making it extremely resistant to light-induced degradation by UV radiation.

RoHS Compliant Pigments
* RoHS Compliant Colorants for Wire/Cable Applications :

A new series of colorants for engineering-grade copolyester TPEs (thermoplastic elastomers) fully compliant with the RoHS Directive has been introduced by Teknor Color Company for use with high-performance TPEs. The twelve colors in the new colorant series are black, blue, light blue, brown, gray, green, orange, purple, red, rose, white, and yellow. Potential applications include wire/cable insulation/jackets, plus fiber and optic buffers. �The new colorants contain no heavy-metal pigments yet provide the same intensity and coloring efficiency as conventional colors for engineering-grade TPEs. The colorants were specifically formulated to concentrates tailored for use with copolyester TPEs in response to this material's growing use as a buffer in optical fiber cables.

* RoHS Compliant Pigments for Fibers and Films:
Two new colors in the PRECISE product line of extremely durable pigments designed for coloring fibers and films are Green 40P601, CI pigment Green 26, a sea foam green color and Blue 40P585, CI pigment Blue 28, a cobalt blue color. Both these new pigments developed by Shepherd Color Co. meet RoHS 2000/95/EC, WEEE 2000/96/EC, Council of Europe AP(89)1, and Australian Standard AS 2070. Additionally the Blue 40P585 also meets FDA 21 CFR 178.3297, CONEG, Toy Safety EN71.3, and the French Positive List. These PRECISE high performance inorganic pigments have extreme durability, outstanding high temperature stability, and are chemically inert as well as light and weather fast.

 
 
 
 
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