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Additives: maintaining quality & appearance under pressure.

Plastic resins are not born beautiful, but countless end products go to market with highly durable visual appeal. Credit a sophisticated appearance-enhancement industry for its wide-ranging ability to add esthetics to plastics' many functional virtues.

However, the pressure to regulate heavy metals in colorants is forcing a re-evaluation of successful, cost-effective product lines. Weighing perceived risks versus benefits, many suppliers are questioning the wisdom of the trend toward legislated restrictions.

J. Lawrence Robinson, executive vice president of the Dry Color Manufacturers Association (DCMA), asserts that the member firms take considerable effort to ensure that their products are safe when used in their intended manner. "The pigments are generally insoluble, solid crystals," he says, "a property that generally prevents them from being absorbed by humans or the environment."

Robinson contends, as do many pigment suppliers, that it is inappropriate for regulators to restrict insoluble pigment compounds along with soluble pollutants without giving due consideration to the characteristic differences between pigments and the regulated element. "This approach to regulations," he maintains, "can cause irreparable harm to our industry, without corresponding benefits for the environment."

With reference specifically to pigments whose manufacture includes the use of heavy metals, Robinson says that the risks are frequently overstated by placing insoluble pigment materials in the same hazard classifications as the elemental metals themselves. "Cadmium pigments are not toxicologically the same as cadmium," he says, "and lead chromate pigments are not toxicologically the same as lead. We have frequently seen this scientifically inappropriate approach taken by the U.S. Occupational Safety and Health Administration (OSHA), the Environmental Protection Agency (EPA), and the Department of Transportation, as well as in legislation currently before Congress and individual states, including the Model Legislation proposed by the Coalition of Northeastern Governors (CONEG) and adopted in several states." Robinson calls for proper understanding of the benefits and risks, in a framework of sound technology and economics, as the true baseline from which to evaluate and respond to restrictive legislation on the use of heavy metals.


The company says a major issue is educating its customers on all the factors involved in replacing heavy metal pigments. Allied has been working with customers to develop products for use in post-consumer recycled material; and it has developed a new line of fluorescent colors, a new line of bright heavy-metal-free colors, and an additive package for use in rotocasting to enhance dispersion and improve part properties.


Americhem/Zipperling now has materials available in semi-commercial quantities for the coating of polymers that provide electrostatic dissipation and yet maintain high optical clarity. The products function independently of relative humidity and can be coated on most packaging substrates. Materials currently available, such as carbon black, nickel-coated graphite, and metallic fibers, can have negative impact on appearance properties, especially in the packaging area, where transparency or clarity is often required. Product development continues in conjunction with Zipperling Kessler of Ahrensburg, Germany.


"It doesn't seem that long ago when the choice of additives and colorants for plastic packaging was virtually unlimited," says Victor Mimeault, vice president, Technical, Ampacet Corp. "This allowed tremendous latitude in developing bright, eye-catching colorant systems, with options ranging from the bright yellows and oranges to special effects, such as pearlescent and fluorescent. However, in recent years, the increasing number of regulatory requirements, both state and federal, has severely restricted the choice of additives and colorants."

Mimeault points out that the bright yellows and oranges always have been great marketing tools. Traditionally formulated with chrome yellows (lead chromate), moly oranges (lead molybdate/lead chromate), and diarylides, these products offered good color value and opacity at a reasonable cost. The use of chrome yellows and moly oranges in plastics packaging has been banned under CONEG and Florida Degradability Rule 17-707. They are subject to reporting requirements under The U.S. Superfund Amendments and Reauthorization Act (SARA) and California Proposition 65, which effectively restrics their use. In addition, the bright yellows and oranges were formulated with diarylide-type pigments, which have now come under pressure because of the possible presence of hazardous by-products when processed above 425 [degrees] F.

Yellow, orange, and red pigments are available that are in compliance with current regulations. However, Mimeault adds, they are at least two to three times more costly. These pigments have not traditionally been used in blowmolding (detergent containers), carry-out bags (grocery sacks, merchandise bags), and flexible packaging.

Mimeault contends that essentially, two choices are left. First, market acceptability of higher priced colorant systems; and second, a trend toward clear or white finished goods, heavily overprinted. "At Ampacet, we are focusing our efforts and technology," he says, "on developing reasonably priced colorant systems that are in compliance, and on developing heavily loaded white products that offer both processing and economic value."


The XL series liquid-phase dispersions for coloring a wide range of thermoplastics feature controlled viscosity of ease of handling over a wide range of temperatures, improved uniform wetting properties, higher pigment loadings, and water miscibility. Formulations are offered in all custom-matched colors, including those designed for food and beverage contact, plus transparent colors and tints. The product line is formulated for a variety of applications, including extruded sheet, profile and pipe extrusions, injection molded parts, structural foam, and blowmolded bottles.

Also announced is a new series of pelletized concentrates, specially designed for coloring a wide range of unplasticized (rigid) PVC compounds. Typical applications include blow-molded bottles, extruded and calendered sheet, profile and pipe extrusions, and injection molded parts. The new concentrates, stabilized to meet U.S. Food and Drug Administration (FDA) Title 21 CFR 178.2650 food additive regulations, provide excellent heat stability and processing characteristics for extended production runs. When used at prescribed letdown ratios in PVC compounds, they show minimal effect on compound viscosities and heat stability. Available in all custom-matched colors, including those designed for food and beverage contact, they also are offered in a stock white along with transparent colors and tints.

Effective November 1, Avecor no longer uses heavy-metal pigments in formulating color concentrates at its North Kansas City, Mo., facility. The company's three other plants, in Los Angeles, Vonore, Tenn., and Vancouver, Wash., will discontinue use of heavy-metal pigments as industry and customer demands dictate.


Among the new Sicoplast products, blends of high performance organics and titanates to match color shades of cadmium- and lead-base pigments, are yellow (10-0290 and 19-0290), orange (36-0330), and red (37-0270, 32-1720, and 37-0280). A new Paliogen, violet-shade perylene, FK4127, has good heat stability and lightfastness for most engineering resins and fibers.

In 1992, the company will produce Sicotan mixed metal oxides (nickel and chrome titanates) using new spray-dried technology to make a dust-free, easy flowing product.


The company has introduced a new line of red, orange, and yellow colorants, available as both dry colors and pellet concentrates, based on insoluble nontoxic forms of cadmium salts. When they are used at the prescribed letdown ratios, molded parts will contain less than 100 parts per billion (ppb) of the soluble toxic form of cadmium.

Also now offered s a line of cellulosic-based pellet concentrates that make it possible for the fabricator to significantly reduce the cost of precolored materials, particularly in less-than-truckload quantities. The company says processors are also able to reduce overall material costs by consolidating purchases of natural cellulosics from the manufacturer and then purchasing the cellulosic-based concentrates.


The Pigments Division has recently acquired FDA registration for five pigments for coloring of polymers and coatings for food contact end-use. The addition of these Cromophtal products brings to thirteen the number of FDA-compliant pigments, in red, yellow, orange, violet, and blue for food packaging materials and toys. The newly registered Cromophtal pigments are Red 3BRF (A2B)-C.I. (Color Index) Pigment Red 177; Red 3B (A3B)-C.I. Pigment Red 177; Red G-C.I. Pigment Red 220; Yellow GR-C.I. Pigment Yellow 95; and Orange GP-C.I. Pigment Orange 64.

Cromophtal DPP Red BP is a recent chromophore for a new class of pigment-diketo-pyrrolo-pyrrol for highly durable, solid red shades. Growing in popularity among high performance organics, it offers high color saturation, excellent weather resistance, and opacity.

Graphitan 6154 graphite pigment provides the basis for silk-luster shades in transparent thermoplastics. Its high opacity is beneficial in mixtures with pearlescent and metallic pigments, creating unique styling effects in plastic packaging, specialty ink, and automotive components and coatings.

Uvitex OB, a fluorescent whitener that adds bluish-white effects and optical brightening, reduces the yellow cast common in certain transparent or white plastics. Offering superior lightfastness, and suitable for films, bottles, and containers, the additive has received FDA clearances for use in packaging and household uses for adhesives, olefins, and PVC.


New product lines for the plastics and fibers markets include the Enduroquin quinacridones. Initial products are a dichlor magenta (PR 122), HP4202; a violet (PC 19), HP4330; and a dimethyl magenta (PR 122), HP4500. Other new products are perylenes, called Endurolenes, including both yellow and blue-shade maroons, coded HP 5179 and HP 5180, respectively; and an opaque anthraquinone (PR 177), marketed as Enduronone and coded HP 7177.

The company also has extended its PR 170 line with the introduction of an opaque yellow shade called Naphthanil red, RT 172D, featuring bright mass tone and good heat stability.


Eastobrite OB, an optical brightener the company has used internally since 1967 to brighten polyester fiber for textile applications, was recently offered for sale to outside customers worldwide in both textiles and a wide range of plastics applications. Demand grew fast, and the product was on allocation for eight months. A new plant that approximately doubles capacity started operation in August, and the material is now readily available, including a finer particle size that eases dispersion in many polymers. Uses for the optical brightener in plastics, typically polypropylene, polyethylene, nylon, polycarbonate, polystyrene, ABS, and PET, include gold ball covers, translucent light covers, outdoor furniture, countertop appliances, containers and closures, and credit cards.


The Meteor Plus series of complex inorganic color pigments is being expanded with the introduction of four colors: Blue-G; Antimony-free Golden; a black; and a buff. Introduced in 1990, the line has a particle size of less than two microns and a narrow particle size distribution for good dispersion and handling ease. The company says that bright colors can be achieved in almost all polymer systems. The line includes pigments with high infrared reflectance that maintain color values and enhance properties of plastics formulated for outdoor use.

Mindust pigments with reduced dusting capacity have soluble cadmium measurements of less than the statutory thresh-old of one part per million, as determined by the EPA's Toxic Characteristic Leaching Procedure for characterizing hazardous waste. The low-dusting pigments offer color value and performance equivalent to that of untreated cadmiums.


The Color Division has added a number of new colors, for PVC siding and window profiles, to its line of mixed metal oxide pigments. V-791 IR was developed as in tinting black to minimize heat buildup in PVC siding. V-9187 iron-free brown is a high tinting strength pigment designed for use in many of today's popular siding colors and window profiles. V-9412 and V-9415 are new nickel titanate yellows with increased yellow value and tinting strength. A number of chrome titanate yellow pigments have also been added to the line. Chrome titanate yellow, one of the workhorse pigments of the PVC siding industry, now finds increased application, along with nickel titanates, in engineering plastics. Chrome and nickel titanate yellows, when combined with selected organic pigments, can be used as alternatives for many cadmium-bearing colors.

Ferro is the exclusive North American distributor for ultra-marine blue and violet pigments produced by Nubiola, S.A., of Barcelona, Spain. Considered nontoxic, the pigments are listed as acceptable by the FDA in the Code of Federal Regulations, Title 21, Section 178.3970, for use in food contact materials. These insoluble inorganic pigments are classified under pigment blue no. 29 and pigment violet no. 15. Ultramarine pigments, suitable for coloring most thermoplastic resins, have good heat stability and lightfastness.


Stantone NTWD colors, introduced last year, offer superior performance in a broad range of water-based polymer systems. Available in 21 basic pigments, they are nonsettling, pourable liquid dispersions. They contain no surfactants or glycols, and all components are FDA regulated. Stantone DB colors, for flexible PVC and also available in multipigment custom blends, are free flowing, reduced-dust concentrates of special effects colorants, including metallic flake, pearlescent, and interference pigments with improved brightness.

A new series of Stantone MC colors, in both single-pigment and multipigment blends, is directed for use in various thermoplastic elastomer as well as conventional elastomeric polymer systems. Based on a universal binder, they are free flowing cubes that provide ease of handling and fast incorporation.

Ten new neon colors have been added to the Stantone paste color line. Based on ultrafine fluorescent pigments in diisodecyl phthalate (DIDP), they are nonsettling pastes particularly suited for vinyl plastisol silkscreen inks and coatings.


The company recently announced a new Compu-Color liquid colorant metering pump, for injection molding and extrusion, that includes separate programmable controller and pumping units. Primary and secondary pumps enable the feeding of color and the processing of additives as needed, and speed color changes. Dual load cells monitor color levels, and flow indicators sense color movement through the equipment.


Icarite IPSZ 130505, a polystyrene photodegradable concentrate designed for use in expandable polystyrene loosefill packaging, can be extruded at commonly used processing temperatures. The recommended letdown ratio is 33:1. An additive system promotes photodegradability of the polystyrene loosefill when exposed to direct sunlight.


"We are now confronted with the CONEG Model Legislation, and variations, requiring that more and more of our major customers, particularly in the packaging industry, certify that their plastic packages will not contain in excess of a specified amount of specific heavy metals," says B.D. Berkman, vice president, Commercial Development. "To maintain our quality obligation to our customers when such situations exist, we have instituted an extension to our incoming raw material Quality Standards program. Each pigment supplier is required to provide us with a trace element analysis for each pigment. Armed with these data, we can certify, where necessary, that our color concentrate formulations will not cause a customer's product to exceed the CONEG requirements."


Pewter PE concentrate W40242 was developed to give a metalic luster and good opacity in polyethylene film or molded parts where a silver, metallic appearance is desired. In pellet form, the additive is typically let down at a 20:1 ratio.

Plycom Huntsman has announced that all polyethylene stock color concentrates have been reformulated to eliminate use of heavy metals. Although the heavy-metal-free formulations meet the company's commitment to environmental safety, not all customers have chosen to switch to them, for reasons ranging from economics to concern over minute color variations due to the absence of the heavy metals.


The company's new policy is that it will no longer intentionally formulate new concentrates with additives or colorants that contain heavy metals. The one exception is when the concentrate is to be used in the manufacture of a durable product and the process requirements can be met only by the use of heavy metal. For nondurable items, those with an expected life span of less than a year, all existing formulations containing heavy metals (cadmium, lead, mercury, and selenium) are being reformulated this year. Reed says it will not accept orders for heavy-metal-containing concentrates for nondurable applications, including product packages and other disposable items, after December 31. The company's intention is to completely eliminate use of heavy metal colorants and additives, even for durable goods, by Dec. 31, 1993.

In the past year, Reed has rematched nearly 98% of its current color offerings with non-cadmium- or non-lead-based compounds. Reed says that while the color matching and testing process has become more complex because of increased use of organic colorants, including concerns over color selection, heat stability, costs, and weatherability, none of the projects has created insurmountable problems.

The company recently unveiled its ReedLite series of heavy-metal-free colorant lines. The first line of twelve standard colors is for type 6 and 6/6 nylons. The ReedLite polycarbonate series is a standard line of ten colors. Additionally, the company is planning to intoduce in the near future a fourteen-color ReedLite olefin series for regulated applications, such as food contact and medical packaging.


Paraloid EXL-5137 gloss reducing agent meets an increasing demand for a matte look in automotive interior parts and electrical/electronic housings. The additive is being evaluated in weathering tests for possible outdoor applications. The all-acrylic modifier reduces reflectance values in 60 [degrees] gloss tests on ABS, polycarbonate, and ABS/PC blends.

Typically, 10% to 15% of the additive is needed to produce a matte finish. Low gloss values are achieved at higher barrel temperatures with the additive/resin blend, thus facilitating flow for molding complex, hard-to-fill parts. A wider processing window can also minimize weld lines. The new flatting agent offers an economic alternative to mechanical embossing or the tight processing controls normally needed to achieve consistent low gloss parts.


The company has a new family of fortified polypropylene products incorporating a unique additive with a refractive index nearly matching that of the base material. It stiffens the polypropylene and improves heat resistance without interferring with coloring traditionally used to increase these two properties.

The Polyfort producs are used by the automotive industry in a multitude of matched colors, replacing high-heat ABS in areas in which the usual colored polypropylenes do not stand up to heat and stress conditions. In addition to precolored materials, Schulman also offers a natural grade with incorporation of a UV inhibitor. For molders who want economy without the responsibility of blending in concentrates, the company supplies ready-to-mold pellet blends or natural and special color concentrates for critical appearance parts. Variations of the basic technology include grades with notched Izod impact and stiffness in the ABS range, with scratch resistance significantly better than that of unmodified polypropylenes. High gloss polypropylenes with an excellent balance of impact and stiffness are also being provided for nonautomotive uses.


The company announced the development of their low-soluble cadmium technology in mid-1990, then considered a major technological improvement, and can certify that the complete cadmium pigment line meets EPA criteria for nonhazardous waste disposal. This means that all their cadmium pigments contain less than 1 ppm of soluble cadmium, based on the TCLP (Toxicity Characteristic Leaching Procedure) test for solubility.


Unlike some colorant suppliers who have moved to eliminate all heavy metals from their products, Spectrum Colors is concerned that a too-rapid switch will be detrimental to consumers and the plastics industry. Terry Golding, vice president for technical services, points out that leads and cadmiums currently used to produce bright reds, yellows, and greens are much more light-stable than their non-heavy-metal counterparts. He adds that the organics typically provide less opacity, which requires higher pigment loadings to achieve comparable results. Thermal stability is also a concern, especially when coloring materials that process at higher temperatures. Finally, the heavy-metal-free colorants are generally more expensive.

"Spectrum Colors will continue to offer both heavy-metal-based colorants and the NHM (No Heavy Metals) line," Golding says, "to meet the processing and performance requirements of the applications. The NHM line meets current environmental regulations regarding the presence of heavy metals in packaging, including CONEG."


The company's response to the two most frequently occurring regulatory concerns today--the CONEG recommended legislation for packaging, and direct food packaging applications regulated by the FDP--is to apply its proprietary dispersion techniques developed for the fiber industry to solutions for film and molding. Brian S. West, technical manager, says that custom formulations utilizing this technology offer single-pigment dispersions of the pertinent colorants for those who wish to formulate their colors. Examples of the single-pigment Base Masterbatch dispersions for food packaging are BMC T616-50% PY95 and BMC R-48-50% PV 19. Techmer PM now offers non-heavy-metal alternatives to the film market's standard colors, such as PM2157E4 Yellow and PM4158E4 Red.


TEK speks, in bead form with a typical letdown ratio of 2% to 3%, create blue, wine, or black specks in a part with a white base color. Colors also can be combined to achieve a red, white, and blue product. Combining a white base color with tiny black specks approaches the look of granite. The product is compatible with polystyrene, polyethylene, polypropylene, ABS, SAN, TPE, and EVA.

Also recently introduced is an improved marble look, typically a base color such as a dark blue streaked with white, or a gray pearl streaked with a rich burgundy. Often, a three-color combination produces an unusual effect. Best results are achieved with a plunger (ram) machine or a screw machine fitted with a mottling kit. Often, a satisfactory marble can be produced with conventional screw equipment, depending on the machine, mold, and molding conditions.

A line of Color Crystals for Teknor Apex's Fireguard (low smoke) plenum compound for wire and cable applications has been introduced. Developed in colors equivalent to Teknor's PE and PVC NEMA and Munsell color concentrate lines, the products are in easy-to-meter and disperse bead form.

Regarding the likelihood of increasing regulation, Bertram Lederer, Teknor Color's president, comments that "legislation such as CONEG, which stems from the state level, no matter how well intended, can lead to various restrictions from state to state that will make compliance particularly burdensome. It is incumbent upon us to help educate our local and national representatives in an effort to ensure that both well-intended and effective legislation is passed. If all we do is respond to legislation after it is passed, rather than try and affect its development and direction, we will suffer the consequences as suppliers to the plastics industry and as consumers."
COPYRIGHT 1991 Society of Plastics Engineers, Inc.
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Author:Wigotsky, Victor
Publication:Plastics Engineering
Date:Nov 1, 1991
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